WO2019036586A1

WO2019036586A1 - SOLUTION CONCENTRATION DETECTION DEVICES

Info

Publication number: WO2019036586A1
Application number: PCT/US2018/046871
Authority: WO
Inventors: Andreas Carlo SCHMIDT; Andrew Martin Bober; Kenneth J. Roach; Kathryn M. SCHMITT
Original assignee: Diversey Inc
Current assignee: Diversey Inc
Priority date: 2017-08-18
Filing date: 2018-08-17
Publication date: 2019-02-21
Anticipated expiration: 2020-02-18
Also published as: WO2019036586A4

Abstract

A concentration of a substance in a sample can be detected by a system that includes an emitter and a detector. The emitter emits, through the sample, electromagnetic energy in a first range of wavelengths that includes a first wavelength and electromagnetic energy in a second range of wavelengths that includes a second wavelength. The substance is at least partially absorptive of electromagnetic energy at the first wavelength and substantially nonabsorptive of electromagnetic energy at the second wavelength. The detector is arranged to detect electromagnetic energy in the first and second ranges of wavelengths. The concentration of the substance in the sample is determined based at least on the intensity of electromagnetic energy received by the detector in the first range of wavelengths and the intensity of electromagnetic energy received by the detector in the second range of wavelengths. The system can be submerged in the sample during operation.

Description

SOLUTION CONCENTRATION SENSING DEVICES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the priority benefit of U.S. Provisional Patent App. No. 62/547, 180 filed on August 18, 2017, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

[0002] The present disclosure is in the technical field of solution concentration detection. More particularly, the present disclosure is directed to systems and methods of testing concentrations of substances in samples of solutions, such as aqueous solutions.

[0003] In many situations, it is desirable to maintain concentrations of particular substances in solutions over time. For example, concentrations of chlorine in swimming pools are maintained in particular ranges, concentrations of cleaning agents in cleaning solutions are maintained in particular ranges, and so forth. These solutions are typically tested occasionally to determine whether the concentrations of the substances are within appropriate ranges. If these concentrations fall outside of the appropriate ranges, the solutions may not function properly. If needed, the concentrations of the substances in the solutions are adjusted to bring the substances within the appropriate ranges.

[0004] Conventional systems and methods for testing concentrations of solutions have many drawbacks. Some testing methods include a user manually inserting a test strip into the solution and the test strip changes color based on the concentration of the substance in the solution. Other testing methods include a user manually collecting a sample of the solution and adding a chemical testing agent to the sample so that the sample will change color based on the concentration of the substance in the sample. It can be difficult to read the results of these color-change testing methods. Users may have difficulty reading the degree in change of color and, therefore, misinterpret the result of the test. This is especially problematic for users who have color vision deficiencies. In addition to the difficulties in reading the tests, the manual nature of these tests requires users to remember to actually perform the tests and then to take the time to perform the tests. This often results in tests not being performed at proper times or not being performed at all.

SUMMARY

[0005] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] In one embodiment, a system is capable of detecting a concentration of a substance in a sample. The system includes a first emitter, a second emitter, a first detector, a second detector, and a controller. The first emitter is configured to selectively emit electromagnetic energy in a first range of wavelengths via a first optical path in the sample. The first range of wavelengths includes a first wavelength and the substance is at least partially absorptive of electromagnetic energy at the first wavelength. The second emitter is configured to selectively emit electromagnetic energy in a second range of wavelengths via a second optical path in the sample. The second range of wavelengths includes a second wavelength and the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength. The first detector is arranged in the first optical path and is configured to detect

electromagnetic energy in the first range of wavelengths. The second detector is arranged in the second optical path and is configured to detect electromagnetic energy in the second range of wavelengths. The controller is configured to receive signals from the first detector indicative of an intensity of electromagnetic energy received by the first detector in the first range of wavelengths, receive signals from the second detector indicative of an intensity of electromagnetic energy received by the second detector in the second range of wavelengths, and determine the concentration of the substance in the sample based at least in part on the signals from the first detector and the signals from the second detector.

[0007] In one example, the system of claim further includes a third emitter and a third detector. The third emitter is configured to selectively emit electromagnetic energy in a third range of wavelengths. The third range of wavelengths includes a third wavelength and the substance is substantially nonabsorptive of electromagnetic energy at the third wavelength. The third detector is arranged in an optical path of the third emitter and the third detector is configured to detect electromagnetic energy in the third range of wavelengths. The controller is further configured to receive signals from the third detector indicative of an intensity of electromagnetic energy received by the third detector in the third range of wavelengths and to determine the concentration of the substance in the sample based at least on the signals from the first detector, the signals from the second detector, and the signals from the third detector. In another example, the first range of wavelengths is within an ultraviolet range of wavelengths, the second range of wavelengths is within the ultraviolet range of wavelengths, and the third range of wavelengths is within a visible light range of wavelengths. In another example, the first detector and the second detector are configured to detect electromagnetic energy across the ultraviolet range of wavelengths, and the third detector is configured to detect electromagnetic energy across the visible light range of wavelengths. In another example, the first range of wavelengths and the second range of wavelengths do not overlap each other within the ultraviolet range of wavelengths.

[0008] In another example, the first wavelength is about 260 nm and the second wavelength is about 295 nm. In another example, each of the first range of

wavelengths and the second range of wavelengths is a range of less than or equal to at least one of about 40 nm, about 20 nm, or about 10 nm. In another example, the system further includes a first feedback detector configured to detect an intensity of the electromagnetic energy emitted by the first emitter and a second feedback detector configured to detect an intensity of the electromagnetic energy emitted by the second emitter. In another example, the controller is further configured to receive signals from the first feedback detector indicative of the intensity of the electromagnetic energy emitted by the first emitter, receive signals from the second feedback detector indicative of the intensity of the electromagnetic energy emitted by the second emitter, and determine the concentration of the substance in the sample based at least on a first ratio of the intensity of electromagnetic energy received by the first detector in the first range of wavelengths to the intensity of the electromagnetic energy emitted by the first emitter and a second ratio of the intensity of electromagnetic energy received by the second detector in the second range of wavelengths to the intensity of the

electromagnetic energy emitted by the second emitter.

[0009] In another example, the first emitter, the second emitter, the first detector, and the second detector are configured to be submerged in the sample. In another example, the controller is configured to be submerged in the sample with at least one of the first emitter, the second emitter, the first detector, and the second detector. In another example, the controller is configured to make periodic determinations whether the concentration of the substance in the sample is within a particular range. In another example, the controller is configured to activate an alert in response to one of the periodic determinations being a determination that the concentration of the substance in the sample is not within the particular range. In another example, the alert includes one or more of a visual alert, an audio alert, or a communication alert.

[0010] In another example, the controller is further configured to determine the concentration of the substance in the sample based at least on the signals from the first detector and the signals from the second detector based on a difference between the intensity of electromagnetic energy received by the first detector and the intensity of electromagnetic energy received by the second detector. In another example, the system is configured to activate the first emitter during a first active period of time, inactivate the first emitter during a first inactive period of time, activate the second emitter during a second active period of time, and inactivate the second emitter during a second inactive period of time. In another example, the controller is further configured to extract a first set of data from the signals from the first detector and to extract a second set of data from the signals from the second detector, where the first set of data is indicative of the intensity of electromagnetic energy received by the first detector during at least a portion of the first active period of time, the second set of data is indicative of the intensity of electromagnetic energy received by the second detector during at least a portion of the second active period of time, and the controller is further configured to determine the concentration of the substance in the sample based at least on the signals from the first detector and the signals from the second detector is based on the first set of data and the second set of data. In another example, the portion of the first active period of time does not include a warmup period of the first emitter during the first active period of time and the portion of the second active period of time does not include a warmup period of the second emitter during the second active period of time. In another example, the first active period of time and the second period of time do not overlap each other.

[0011] In another example, the first emitter is configured to emit electromagnetic energy only within the first range of wavelengths and wherein the second emitter is configured to emit electromagnetic energy only within the second range of wavelengths. In another example, the first detector and the second detector are a single detector configured to detect electromagnetic energy in a detection range that encompasses the first and second range of wavelengths. In another example, the first detector and the second detector are separate detectors and the first range of wavelengths does not overlap the second range of wavelengths. In another example, the first detector is configured to detect electromagnetic energy only within the first range of wavelengths and wherein the second detector is configured to detect electromagnetic energy only within the second range of wavelengths. In another example, the first emitter and the second emitter are a single emitter configured to selectively emit electromagnetic energy in an emission range that encompasses the first and second range of wavelengths. In another example, the first emitter and the second emitter are separate emitters, and wherein the first range of wavelengths does not overlap the second range of

wavelengths. In another example, the substance is at least partially absorptive of electromagnetic energy at the first wavelength by absorbing at least 50% of electromagnetic energy at the first wavelength. In another example, the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength by permitting transmittance of at least 90% of electromagnetic energy at the second wavelength.

[0012] In another embodiment, a method may be performed to detect a concentration of a substance in a sample. The method includes causing, by a controller, emission of electromagnetic energy from at least one emitter via at least one optical path in the sample. The electromagnetic energy includes electromagnetic energy in a first range of wavelengths that includes a first wavelength and electromagnetic energy in a second range of wavelengths that includes a second wavelength. The substance is at least partially absorptive of electromagnetic energy at the first wavelength, and wherein the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength. The method further includes receiving, by the controller from at least one detector arranged in at least one optical path of the at least one emitter and configured to detect electromagnetic energy in the first and second ranges of wavelengths, signals indicative of an intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths and signals indicative of an intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths. The method further includes determining, by the controller, the controller is further configured to determine the concentration of the substance in the sample based at least on the signals indicative of the intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths and the signals indicative of the intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths.

[0013] In one example, the at least one emitter includes a first emitter configured to emit electromagnetic energy only within the first range of wavelengths and a second emitter configured to emit electromagnetic energy only within the second range of wavelengths. In another example, causing emission of electromagnetic energy from the at least one emitter includes activating, by the controller, the first emitter during a first active period of time, inactivating, by the controller, the first emitter during a first inactive period of time, activating, by the controller, the second emitter during a second active period of time, and inactivating, by the controller, the second emitter during a second inactive period of time. In another example, the method further includes extracting a first set of data from the signals indicative of an intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths, where the first set of data is indicative of the intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths during at least a portion of the first active period of time. In another example, the method further includes extracting a second set of data from the signals indicative of an intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths, where the second set of data is indicative of the intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths during at least a portion of the second active period of time. In another example, the controller is further configured to determine the concentration of the substance in the sample based at least on the first set of data and the second set of data. In another example, the portion of the first active period of time does not include a warmup period of the first emitter during the first active period of time; and the portion of the second active period of time does not include a warmup period of the second emitter during the second active period of time.

[0014] In another example, the at least one emitter includes a first detector configured to detect electromagnetic energy only in the first range of wavelengths and a second detector configured to detect electromagnetic energy only in the second range of wavelengths. In another example, the first range of wavelengths is within an ultraviolet range of wavelengths, the second range of wavelengths is within the ultraviolet range of wavelengths, and the first range of wavelengths does not overlap the second range of wavelengths. In another example, the at least one emitter includes a third detector configured to detect electromagnetic energy only in a third range of wavelengths, wherein the third range of wavelengths is within a visible light range of wavelengths, and wherein the substance is substantially nonabsorptive of electromagnetic energy at the third wavelength.

[0015] In another example, the causing of the emission of electromagnetic energy from at least one emitter and the receiving of the signals are performed while the at least one emitter and the at least one detector are submerged in the sample. In another example, the controller is configured to be submerged in the sample with at least one emitter and the at least one detector. In another example, the method further includes making, by the controller, periodic determinations whether the concentration of the substance in the sample is within a particular range. In another example, the method further includes activating, by the controller, an alert in response to one of the periodic determinations being a determination that the concentration of the substance in the sample is not within the particular range.

[0016] In another example, an illustrative device for determining a compound

concentration, includes a working electrode configured to be placed in a solution that includes a compound, and a potentiostat electrically connected to the working electrode. The potentiostat is configured to deliver a potential to the working electrode. The device also includes a sensor configured to detect an initial electrical property resulting from the potential and a delayed electrical property that results after the potential is delivered for a time period. The device further includes a controller configured to determine a concentration of a compound in a solution based at least in part on the initial electrical property and at least in part on the delayed electrical property.

[0017] In another example, an illustrative device for determining a compound

concentration includes a working electrode configured to be placed in a solution that includes a compound, and a potentiostat electrically connected to the working electrode. The potentiostat is configured to deliver a potential to the working electrode. The device also includes a sensor configured to detect an electrical property resulting from the potential. The device further includes a controller configured to determine a

concentration of the compound in the solution based at least in part on the electrical property. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The foregoing aspects and many of the attendant advantages of the disclosed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

[0019] Fig. 1 depicts an example of a three-bay sink containing aqueous solutions, in accordance with the embodiments described herein;

[0020] Fig. 2A depicts a chart showing absorbance and transmittance values of electromagnetic energy at various wavelengths in a sample of 400 ppm of quaternary ammonium compound in water in accordance with the embodiments described herein;

[0021] Fig. 2B depicts a table showing some of the values of wavelengths, absorbance, and transmittance in the chart shown in Fig. 2A, in accordance with the embodiments described herein;

[0022] Fig. 3A depicts a first automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the

embodiments described herein;

[0023] Fig. 3B depicts a second automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the

embodiments described herein;

[0024] Fig. 3C depicts a third automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the embodiments described herein;

[0025] Fig. 3D depicts a fourth automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the

embodiments described herein;

[0026] Fig. 3E depicts a fifth automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the

embodiments described herein;

[0027] Fig. 3F depicts a sixth automated system for detecting quaternary ammonium compound utilizing the absorbance properties of electromagnetic energy at different wavelengths by the quaternary ammonium compound to determine a concentration of the quaternary ammonium compound in a solution, in accordance with the

embodiments described herein;

[0028] Fig. 4 depicts an embodiment of a submergible concentration sensor, in accordance with the embodiments described herein;

[0029] Fig. 5 depicts an embodiment of a ware washing station that includes the sink shown in Fig. 1 and the concentration sensor shown in Fig. 4, in accordance with the embodiments described herein;

[0030] Fig. 6A depicts a chart showing signals generated from detectors in a system that is usable to detect a concentration of a quaternary ammonium compound in a sample of a solution, in accordance with the embodiments described herein; [0031] Fig. 6B depicts a chart showing signals generated from feedback detectors in a system that is usable to detect a concentration of a quaternary ammonium compound in a sample of a solution, in accordance with the embodiments described herein;

[0032] Fig. 7 A depicts a more detailed view of a portion of the data shown in the chart of Fig. 6A, in accordance with the embodiments described herein;

[0033] Fig. 7B depicts a more detailed view of a portion of the data shown in the chart of Fig. 6B, in accordance with the embodiments described herein;

[0034] Fig. 8 depicts an example embodiment of a system that may be used to implement some or all of the embodiments described herein;

[0035] Fig. 9 depicts a block diagram of an embodiment of a computing device, in accordance with the embodiments described herein;

[0036] Fig. 10 is a block diagram of a device 700 that uses an electrochemical technique to measure the concentration of a compound present in a solution in accordance with embodiments described herein;

[0037] Fig. 1 1 is a flow diagram depicting operations performed by a device to detect compound concentration in accordance with an illustrative embodiment.

[0038] Fig. 12A depicts tests run on various quaternary ammonium compound and water dilutions in accordance with embodiments described herein;

[0039] Fig. 12B depicts the effect of calcium concentrations in the water in accordance with the embodiments described herein;

[0040] Fig. 12C depicts current versus time after 2000 ms of applied potential to a solution in accordance with embodiments described herein;

[0041] Fig. 12D depicts maximum current versus time resulting from the applied potential to the solution in accordance with embodiments described herein; [0042] Fig. 12E depicts current versus time for a solution with 60 mg Ca and a solution with quaternary ammonium compound and 60 mg Ca in accordance with embodiments described herein;

[0043] Fig. 13A depicts measurements of Oxivinwater dilutions in accordance with embodiments described herein;

[0044] Fig. 13B depicts the linear response of the dilutions from Fig. 13A in accordance with embodiments described herein; and

[0045] Fig. 14 depicts a dispenser in accordance with embodiments described herein.

DETAILED DESCRIPTION

[0046] The present disclosure describes embodiments of systems and methods of testing concentrations of substances in samples of solutions, such as aqueous solutions. In particular, the embodiments disclosed herein are directed to systems and methods that can automatically make periodic determinations of concentration of a substance in the solution and cause an alarm to be activated if it is determined that the concentration of the substance falls outside of an acceptable range. Because these automatic determinations do not require any operator intervention, the systems and methods do not rely on an operator to remember to perform a test, to accurately perform the test, and/or to accurately interpret the results of the test. Thus, the systems and methods described herein may overcome the drawbacks described above with respect to manual testing methods.

[0047] Depicted in Fig. 1 is an example of a three-bay sink 100 containing aqueous solutions. The sink 100 includes bays 104, 106, and 108. Each of the bays 104, 106, and 108 holds an aqueous solution 1 14, 1 16, or 1 18. The sink 100 also includes a faucet 120 configured to selectively add water to the bays 104, 106, and 108. The aqueous solutions 1 14, 1 16, and 1 18 in the bays 104, 106, and 108 can be used for a variety of purposes. [0048] In some cases, the sink 100 can be used in a commercial ware washing environment, such as food service facilities (e.g., commercial kitchens, restaurants, etc.), to wash dishes and other kitchen ware. In these cases, the aqueous

solutions 1 14, 1 16, and 1 18 in the bays 104, 106, and 108 may be different from each other. For example, the aqueous solution 1 14 may include a solution of dish washing soap and water that can be used to wash the kitchen ware, the aqueous solution 1 16 may include mostly water that can be used to rinse the kitchen ware, and the aqueous solution 1 18 may include a solution of sanitizer in water that can be used to sanitize the kitchen ware. This arrangement of the bays 104, 106, and 108 provides a convenient environment for kitchen staff to wash, rinse, and sanitize kitchen ware.

[0049] One difficulty with the use of the sink 100 is maintaining appropriate

concentrations of substances in the aqueous solution 1 14, 1 16, and 1 18. For example, in the case where the aqueous solution 1 18 is a sanitizing solution, the concentration of the sanitizer in the aqueous solution 1 18 should be maintained within a particular range. If the concentration of sanitizer falls below that range, the aqueous solution 1 18 will be ineffective at sanitizing the kitchen ware. In addition, failure to maintain proper sanitizer concentration in ware washing stations is a common citation by health inspection authorities, resulting in fines or other penalties to the food service facility.

[0050] Because of the risks involved with sanitizer concentration falling out of the proper range, food service facilities typically require their staffs to regularly test the sanitizer concentration in ware washing stations. However, as noted above, there are a number of drawbacks to manual color-changing systems and methods for testing concentrations of substances in solutions (e.g. , test strips, adding chemical testing agents to samples, etc.). For example, manual color-changing systems and methods require the staff members to remember to perform the testing throughout the day and then to actually perform the test when they remember. In the embodiment of the sanitizing solution, food service facility staff members may not remember to test the sanitizer concentration during their work shift, or may simply not know or understand the importance of compliance with sanitizer concentration regulations. In another example, manual color- changing systems and methods typically require performance of a specific set of instructions to properly perform the test. In some cases, food service facility staff members may be not be properly trained to accurately perform the steps of the test. In another example, manual color-changing systems and methods produce results that are difficult to read and interpret. Test strips are not always consistent from lot to lot so that test strips from different lots may produce different results. Color-bases tests are also difficult or impossible for staff members with color vision deficiencies.

[0051] Disclosed herein are embodiments of systems and methods for testing concentrations of substances in solutions that address the drawbacks with manual color-changing testing. In particular, in some embodiments, systems are capable of monitoring a concentration of a substance in a solution in real-time without user input. In some embodiments, the systems provide an indication of whether the concentration is in an appropriate range that can be easily understood by users that do not have special training or skills. In some embodiments, the systems are capable of automatically detecting concentrations of solutions either continuously or at specific times (e.g., periodic intervals). These embodiments eliminate the need for users to remember to test the solution and provide a clear indication to when it is time to adjust the

concentration of the solution. These embodiments reduce training time of new staff members and allow staff members to focus on other aspects of their job by removing the active testing from their duties.

[0052] The embodiments described herein emit electromagnetic energy at different wavelengths through the sample and detect intensity of the electromagnetic energy at the different wavelengths after passing through the sample. The different wavelengths include one wavelength at which a substance in the sample is at least partially absorptive and another wavelength at which the substance in the sample is

substantially nonabsorptive. The concentration of the substance in the sample can be determined based at least on the detected intensity of the electromagnetic energy at the different wavelengths. [0053] As used herein, the terms "absorptive" and "nonabsorptive" may be defined in terms of absorbance and/or transmittance. In some embodiments, transmittance is the fraction of incident electromagnetic energy that is transmitted through a sample. In particular, transmittance can be measured as the amount of radiant flux transmitted by a material to the amount of radiant flux incident upon the material:

where Τ_λ is the transmittance at a wavelength of the m is the spectral radiant flux at the wavelength transmitted by the material, and

pectral radiant flux at the wavelength received by the material. Transmittance can be described as a fraction, a percentage, or any other indication of the portion of electromagnetic energy that passes through the material. In some embodiments, absorbance the common logarithm of the ratio of incident to transmitted radiant power through a material:

where Α_λ is the absorbance in wavelength of the material. Combining equations (1 ) and (2) provides a relationship between absorbance and transmittance:

Αλ = -logio(¾ (3)

Absorbance is dimensionless, and may be defined in term of "arbitrary units" (AU).

[0054] In some embodiments, a substance in a solution is at least partially absorptive of electromagnetic energy at a wavelength if the solution has an absorbance of that electromagnetic energy that is at or above [or a transmittance that is at or below] any one of the following values: 1 .30 AU [5%], 1 .00 AU [1 0%], 0.824 AU [15%], 0.699 AU [20%], 0.602 AU [25%], 0.523 AU [30%], 0.456 AU [35%], 0.398 AU [40%], 0.347 AU [45%], 0.301 AU [50%], 0.260 AU [55%], 0.222 AU [60%], 0.187 AU [65%], 0.155 AU [70%], 0.125 AU [75%], 9.69x 1 0^"2 AU [80%], 7.06x 1 0^"2 AU [85%], 4.58x 10^"2 AU [90%], 2.23x 1 0^"2 AU [95%], or any other value. In some embodiments, a substance in a solution is substantially nonabsorptive of electromagnetic energy at a wavelength if the solution has an absorbance of that electromagnetic energy that is at or below [or a transmittance that is at or above] any one of the following values: 1 .30 AU [5%], 1 .00 AU [10%], 0.824 AU [15%], 0.699 AU [20%], 0.602 AU [25%], 0.523 AU [30%], 0.456 AU [35%], 0.398 AU [40%], 0.347 AU [45%], 0.301 AU [50%], 0.260 AU [55%], 0.222 AU [60%], 0.1 87 AU [65%], 0.1 55 AU [70%], 0.125 AU [75%], 9.69x 10^"2 AU [80%], 7.06X 1 0-² AU [85%], 4.58x 10^"2 AU [90%], 2.23x 10^"2 AU [95%], or any other value. For example, a solution may be considered at least partially absorptive of electromagnetic energy at a wavelength if the solution has an absorbance of that electromagnetic energy that is at or above 0.125 AU [or a transmittance that is at or below 75%] and the solution may be considered substantially nonabsorptive of the electromagnetic energy at the wavelength if the solution has an absorbance of that electromagnetic energy that is at or below 4.58x 10^"2 AU [or a transmittance that is at or above 90%]. Any other combination of values may define the limits of a solution being at least partially absorptive of the electromagnetic energy and substantially nonabsorptive of the electromagnetic energy.

[0055] Many of the examples described herein are described in terms of monitoring concentrations of quaternary ammonium compound in an aqueous solution. Quaternary ammonium compound is a known sanitizing agent, such as the sanitizing agent in the aqueous solution 1 1 8. Using this example, the concentration of quaternary ammonium compound in the aqueous solution 1 18 may need to be monitored to ensure that the concentration of quaternary ammonium remains in an appropriate range for sanitization of kitchen ware. While the embodiments described herein may describe determining concentrations of quaternary ammonium compound in an aqueous solution, it will be understood that the systems and methods described herein can be used to determine concentrations of other substances in other types of solutions.

[0056] Depicted in Fig. 2A is a chart showing absorbance and transmittance values of electromagnetic energy at various wavelengths in a sample of 400 ppm of quaternary ammonium compound in water. Depicted in Fig. 2B is a table showing some of the values of wavelengths, absorbance, and transmittance in the chart shown in Fig. 2A. As can be seen in Figs. 2A and 2B, absorbance at the quaternary ammonium compound is high at lower wavelengths (e.g., below 225 nm), but then the absorbance drops down to 0.139 AU (transmittance rises to 72.6%) at 239 nm. From there, the absorbance increases and three local maxima are shown at 257 nm, 262 nm, and 269 nm. The absorbance is above 0.300 AU (transmittance is below 50%) at each of the three local maxima. As the wavelength increases from 269 nm, the absorbance decreases until the absorbance reaches 4.01 ^χ10^~2 AU (transmittance increases to 91 .2%) at a wavelength of 290 nm. As the wavelength increases from 290 nm until at least over 600 nm, the absorbance remains below 4.6x10^"2 AU (transmittance remains above 90%). In particular, at a wavelength of 500 nm in the visible spectrum range, the absorbance is 1 .26*10^"2 AU (transmittance is 97.1 %).

[0057] The absorbance properties of electromagnetic energy at different wavelengths by quaternary ammonium compound can be useful to determine a concentration of the quaternary ammonium compound in a solution. As will be discussed in greater detail below, automated systems for detecting quaternary ammonium compound may utilize the absorbance properties of electromagnetic energy at different wavelengths by quaternary ammonium compound to determine a concentration of quaternary

ammonium compound in a solution. Examples of such automated systems are depicted in Figs. 3A to 3F.

[0058] Fig. 3A depicts a system 200 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 200 includes a controller 220. In the depicted embodiment, the controller 220 includes a computing device 222, a power source 224, and a communications interface 226. The computing device 222 may include a processing element (e.g., a programmable logic device, a microprocessor, an integrated circuit, etc.) and/or memory (e.g., flash memory, etc.) that enable the controller 220 to perform particular functions described below. The power source 224 may be a battery, a rechargeable battery, an electrochemical cell, or any other source of electrical power. The power source 224 may be arranged to power the components of the controller 220 and/or other components of the system 200. In some embodiments, the communications interface 226 is a wired communications interface (e.g., serial port, universal serial bus (USB) port, etc.) or a wireless communication interface (e.g., a WiFi transceiver, a Bluetooth transceiver, etc.). The communications interface 226 may be arranged to communicate with a device outside of the system 200, such as a remote computing device, an alert device, or any other type of device.

[0059] The system 200 further includes a first emitter 230 and a second emitter 232. The first emitter 230 is configured to emit electromagnetic energy in a first range of wavelengths via a first optical path in the sample. The first range of wavelengths includes a first wavelength and a substance in the sample is at least partially absorptive of electromagnetic energy at the first wavelength. Using quaternary ammonium compound as an example of the substance, the first range of wavelengths includes a first wavelength of 260 nm and the quaternary ammonium compound is at least partially absorptive of electromagnetic energy at 260 nm (e.g., because the quaternary ammonium compound has a transmittance at or below 75% at 260 nm). In some embodiments, the first range of wavelengths may be centered about the first

wavelength, such as a range of about 255 nm to about 265 nm, a range of about 250 nm to about 270 nm, or range of about 240 nm to about 290 nm. In some

embodiments, the first range of wavelengths may not be centered about the first wavelength, such as a range from about 250 nm to about 265 nm where the first wavelength is 260 nm. In some embodiments, any of the ranges of wavelengths disclosed herein may be a range of less than or equal to at least one of about 40 nm, about 20 nm, or about 10 nm.

[0060] The second emitter 232 is configured to emit electromagnetic energy in a second range of wavelengths via a second optical path in the sample. The second range of wavelengths includes a second wavelength and the substance in the sample is substantially nonabsorptive of electromagnetic energy at the second wavelength. Using quaternary ammonium compound as an example of the substance, the second range of wavelengths includes a second wavelength of 295 nm and the quaternary ammonium compound is substantially nonabsorptive of electromagnetic energy at 295 nm (e.g., because the quaternary ammonium compound has a transmittance at or above 90% at 295 nm). In some embodiments, the second range of wavelengths may be centered about the second wavelength, such as a range of about 290 nm to about 300 nm, a range of about 285 nm to about 305 nm, or range of about 275 nm to about 315 nm. In some embodiments, the first range of wavelengths may not be centered about the first wavelength, such as a range from about 290 nm to about 305 nm where the first wavelength is 295 nm. In some embodiments, the first range of wavelengths overlaps the second range of wavelengths. In other embodiments, the first range of wavelengths does not overlap the second range of wavelengths.

[0061] The system 200 further includes a first detector 250 and a second detector 252. The first detector 250 is arranged in the first optical path from the first emitter 230 and the second detector 252 is arranged in the second optical path from the second emitter 232. The first detector 250 includes a first photodetector 260 configured to detect electromagnetic energy in the first range of wavelengths and to generate a signal indicative of an intensity of electromagnetic energy received by the first detector 250 in the first range of wavelengths. The second detector 252 includes a second

photodetector 262 configured to detect electromagnetic energy in the second range of wavelengths and to generate a signal indicative of an intensity of electromagnetic energy received by the second detector 252 in the second range of wavelengths.

[0062] The controller 220 is communicatively coupled to the first emitter 230, the second emitter 232, the first detector 250, and the second detector 252. The controller 220 is adapted to control operations of the first emitter 230 and the second emitter 232. In some embodiments, the controller 220 is adapted to control operations of the first emitter 230 and the second emitter 232 by controlling an amount of electrical power supplied from the power source 224 to each of the first emitter 230 and the second emitter 232. The controller 220 is also configured to receive signals from the first detector 250 indicative of the intensity of electromagnetic energy received by the first detector 250 in the first range of wavelengths and to receive signals from the second detector 252 indicative of the intensity of electromagnetic energy received by the second detector 252 in the second range of wavelengths.

[0063] The controller 220 is also adapted to determine the concentration of the substance in the sample based at least in part on the signals from the first detector 250 and the signals from the second detector 252. For example, the computing device 222 may determine the concentration of the substance in the sample based at least in part on a difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the second detector 252. As noted above, the substance is at least partially absorptive of electromagnetic energy at the first wavelength in the first range of wavelengths and the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength in the second range of wavelengths. Because of these properties of the substance, the intensity of the light in the second range of wavelengths may indicate a "baseline" of transmission of electromagnetic energy in the solution absent the substance and the intensity of the light in the first range of wavelengths may indicate the transmission of electromagnetic energy in the solution with the substance included. In this way, the concentration of the substance in the solution may be determined as a function of the difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the second detector 252. It will be noted that, under practical conditions, neither the output of an emitter nor the response curve of a detector will likely be substantially uniform across its corresponding range of wavelengths. In some embodiments, the controller 220 is configured to integrate an entire output within a corresponding range of wavelengths without regard to uniformity of the output is within the corresponding range of wavelengths. Configuring the controller 220 in this way may be useful in particular situations, such as when a range of wavelengths (e.g., the first range of wavelengths) is not centered about a particular wavelength of interest (e.g., the first wavelength).

[0064] In some embodiments, the first and second emitters 230 and 232 are limited to emitting electromagnetic energy only within the first and second ranges of wavelengths, respectively. For example, the first emitter 230 may include an electromagnetic energy source that generates electromagnetic energy only within the first range of wavelengths. In another example, the first emitter 230 includes an electromagnetic energy source that generates electromagnetic energy inside and outside of the first range of wavelengths, but also includes a bandpass filter that permits electromagnetic energy only within the first range of wavelengths to pass into the sample.

[0065] In some embodiments, where the first and second emitters 230 and 232 are limited to emitting electromagnetic energy only within the first and second ranges of wavelengths, respectively, the first and second detectors 250 and 252 may be able to detect electromagnetic energy in ranges that are greater than the first and second ranges of wavelengths. For example, the first and second emitters 230 and 232 may be configured to emitting electromagnetic energy only within a range of about 250 nm to about 270 nm and a range of about 285 nm to about 305 nm, respectively. Both of these ranges are within the ultraviolet (UV) range (i.e., between 10 nm and 400 nm). In this example, each of the first and second detectors 250 and 252 may be an UV detector configured to detect electromagnetic energy across the entire range of UV wavelengths or a across a portion of the range of UV wavelengths that includes wavelengths between 250 nm and 305 nm.

[0066] In some embodiments, the first and second detectors 250 and 252 are limited to detecting electromagnetic energy only within the first and second ranges of

wavelengths, respectively. For example, the first photodetector 260 in the first detector 250 may detect electromagnetic energy only within the first range of

wavelengths. In another example, the first photodetector 260 in the first detector 250 may detect electromagnetic energy source that generates electromagnetic energy inside and outside of the first range of wavelengths, but the first detector 250 also includes a bandpass filter that permits electromagnetic energy only within the first range of wavelengths to reach the first photodetector 260.

[0067] In some embodiments, where the first and second detectors 250 and 252 are limited to detecting electromagnetic energy only within the first and second ranges of wavelengths, respectively, the first and second emitters 230 and 232 may be able to emit electromagnetic energy in ranges that are greater than the first and second ranges of wavelengths. For example, the first and second detectors 250 and 252 may be configured to detect electromagnetic energy only within a range of about 250 nm to about 270 nm and a range of about 285 nm to about 305 nm, respectively. Both of these ranges are within the UV range. In this example, each of the first and second emitters 230 and 232 may be an UV emitter configured to emit electromagnetic energy across the entire range of UV wavelengths or across a portion of the range of UV wavelengths that includes the wavelengths between 250 nm and 305 nm..

[0068] Fig. 3B depicts another system 202 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 202 includes the controller 220, the first emitter 230, the second emitter 232, the first detector 250, and the second detector 252, similar to the system 200. The system 202 further includes a third emitter 234 configured to emit electromagnetic energy in a third range of wavelengths via a third optical path in the sample. The third range of wavelengths includes a third wavelength and the substance in the sample is

substantially nonabsorptive of electromagnetic energy at the third wavelength. Using quaternary ammonium compound as an example of the substance, the third range of wavelengths includes a third wavelength of 500 nm and the quaternary ammonium compound is substantially nonabsorptive of electromagnetic energy at 500 nm (e.g., because the quaternary ammonium compound has a transmittance at or above 90% at 500 nm).

[0069] The system 202 further includes a third detector 254. The third detector 254 is arranged in the third optical path from the third emitter 234. The third detector 254 includes a third photodetector 264 configured to detect electromagnetic energy in the third range of wavelengths and to generate a signal indicative of an intensity of electromagnetic energy received by the third detector 254 in the third range of wavelengths. The controller 220 is communicatively coupled to the third emitter 234 and to the third detector 254. The controller 220 is adapted to control operation of the third emitter 234. In some embodiments, the controller 220 is adapted to control operation of the third emitter 234 by controlling an amount of electrical power supplied from the power source 224 to the third emitter 234. The controller 220 is also configured to receive signals from the third detector 254 indicative of the intensity of electromagnetic energy received by the third detector 254 in the third range of wavelengths.

[0070] In Fig. 3B, the controller 220 is also adapted to determine the concentration of the substance in the sample based at least in part on the signals from the first detector 250, the signals from the second detector 252, and the signals from the third detector 254. For example, the computing device 222 may determine the concentration of the substance in the sample based at least in part on a function of (1 ) the difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the second detector 252 and (2) the difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the third detector 254. As noted above, the substance is at least partially absorptive of electromagnetic energy at the first wavelength in the first range of wavelengths, the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength in the second range of wavelengths, and the substance is substantially nonabsorptive of electromagnetic energy at the third wavelength in the third range of wavelengths. Because of these properties of the substance, each of the intensities of the light in the second and third ranges of wavelengths may indicate a "baseline" of transmission of electromagnetic energy in the solution absent the substance and the intensity of the light in the first range of wavelengths may indicate the transmission of electromagnetic energy in the solution with the substance included. In this way, the concentration of the substance in the solution may be determined as a function of (1 ) the difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the second detector 252 and (2) the difference between the intensity of electromagnetic energy received by the first detector 250 and the intensity of electromagnetic energy received by the third detector 254. In this example, the controller 220 uses two "baseline" readings in an effort to arrive at a more accurate determination of the concentration of the substance in the solution. Using two baseline readings may also permit the controller to determine the presence of scatter components, such as soil or other contaminants, in the solution.

[0071] Similar to the description above with respect to the system 200, of one or both of the emitters 230, 232, and 234 or the detectors 250, 252, and 254 may be limited to their respective ranges of wavelengths. More specifically, one or both of the emitter 230 or the detector 250 may be limited to emit or detect electromagnetic energy only within the first range of wavelengths; one or both of the emitter 232 or the detector 252 may be limited to emit or detect electromagnetic energy only within the second range of wavelengths; and one or both of the emitter 234 or the detector 254 may be limited to emit or detect electromagnetic energy only within the third range of wavelengths. In this way, the emitters 230, 232, and 234 and the detectors 250, 252, and 254 may be selected to minimize the cost of the system 202. For example, it may be less expensive to limit the emitters 230, 232, and 234 to emit electromagnetic energy only within their respective ranges of wavelengths than to limit the detectors 250, 252, and 254 to their respective ranges of wavelengths. Using quaternary ammonium compound as an example, the first emitter 230 may be configured to emit electromagnetic energy only within a range from about 250 nm to about 270 nm, the second emitter 232 may be configured to emit electromagnetic energy only within a range from about 285 nm to about 305 nm, the third emitter 234 may be configured to emit electromagnetic energy only within a range from about 480 nm to about 520 nm, while the first and second detectors 250 and 252 are configured to detect electromagnetic energy across the UV range of wavelengths, and the third detector 254 is configured to detect electromagnetic energy across the visible range of wavelengths (i.e., between about 400 nm and about 700 nm). [0072] Fig. 3C depicts another system 204 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 204 is the same as the system 200, except that the system 204 includes a first feedback detector 240 and a second feedback detector 242. The first feedback detector 240 is configured to detect an intensity of the electromagnetic energy emitted by the first emitter 230. The second feedback detector 242 is configured to detect an intensity of the electromagnetic energy emitted by the second emitter 232. The first and second feedback detectors 240 and 242 are capable of generating signals indicative of the intensities of the electromagnetic energy emitted by the first and second emitters 230 and 232, respectively.

[0073] The controller 220 is communicatively coupled to each of the first and second feedback detectors 240 and 242. The controller 220 is configured to receive signals from the first feedback detector 240 indicative of the intensity of the electromagnetic energy emitted by the first emitter 230 and to receive signals from the second feedback detector 240 indicative of the intensity of the electromagnetic energy emitted by the second emitter 230. The controller 220 is further configured to determine a first ratio of the intensity of electromagnetic energy received by the first detector 250 in the first range of wavelengths to the intensity of the electromagnetic energy emitted by the first emitter 230. The controller 220 is further configured to determine a second ratio of the intensity of electromagnetic energy received by the second detector 252 in the second range of wavelengths to the intensity of the electromagnetic energy emitted by the second emitter 232. The controller 220 is configured to determine the concentration of the substance in the sample based at least on the first and second ratios.

[0074] The use of the first and second feedback detectors 240 and 242 in the

system 204 allows the system 204 to remove variability of the intensities of the first and second emitters 230 and 232. For example, when the first and second emitters 230 and 232 are first brought into service, they may have substantially similar intensities. However, as time passes, the intensities of the first and second emitters 230 and 232 may decrease at different rates. The first and second feedback detectors 240 and 242 are capable of detecting the intensities of the first and second emitters 230 and 232 in real time and used to weight the readings of the first and second detectors 250 and 252. In this way, the controller 220 may be able to determine a relatively accurate

concentration of the substance in the solution even if the first and second emitters 230 and 232 do not emit electromagnetic energy at the same levels of intensity.

[0075] The use of the first and second feedback detectors 240 and 242 in the

system 204 can allow for other benefits. In one example, the signals received from the feedback detectors 240 and 242 may be used by the controller 220 to determine a health of the first and second emitters 230 and 232. Over time, the operation of the first and second emitters 230 and 232 may deteriorate over time (e.g., over the course of weeks, months, etc.). For example, the controller 220 may be configured to compare signals from the first feedback detector 240 across particular periods of time period (e.g., over a particular number of weeks, a particular number of months, a particular number of years, etc.). The controller 220 may determine that the signals from the first feedback detector 240 indicate a significant change in the intensity of the

electromagnetic energy emitted by the first emitter 230 at the beginning of the period of time and the intensity of the electromagnetic energy emitted by the first emitter 230 at the end of the period of time. In such as case, the controller 220 may indicate that the first emitter 230 is failing and should be replaced. The controller 220 may do the same for the second emitter 232 using the signals from the second feedback detector 242 or for any other emitter disclosed herein using signals from its corresponding feedback detector.

[0076] Fig. 3D depicts another system 206 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 206 is the same as the system 202, except that the system 206 includes the first feedback detector 240, the second feedback detector 242, and a third feedback detector 244. The first and second feedback detectors 240 and 242 are the same as the first and second feedback detectors 240 and 242 depicted in Fig. 3C. The third feedback detector 244 is configured to detect an intensity of the electromagnetic energy emitted by the third emitter 234. The third feedback detector 244 is capable of generating signals indicative of the intensity of the electromagnetic energy emitted by the third emitter 234.

[0077] The controller 220 is communicatively coupled to the third feedback detector 244. The controller 220 is configured to receive signals from the third feedback detector 244 indicative of the intensity of the electromagnetic energy emitted by the third emitter 234. In addition to determining the first and second ratios (as discussed above with respect to Fig. 3C), the controller 220 is further configured to determine a third ratio of the intensity of electromagnetic energy received by the third detector 254 in the third range of wavelengths to the intensity of the electromagnetic energy emitted by the third emitter 234. The controller 220 is configured to determine the concentration of the substance in the sample based at least on the first, second, and third ratios.

[0078] The embodiments depicted in Figs. 3A to 3D include two and three pairs of emitters and detectors. As described above, this arrangement allows for a

concentration of a substance to be detected by passing electromagnetic energy through the solution at one wavelength where the substance it at least partially absorptive ("measurement" wavelengths) and at one or two wavelengths where the substance is substantially nonabsorptive ("baseline" wavelengths). It will be noted that any number of pairs of emitters and detectors can be used to pass any desired number of

measurement wavelengths and baseline wavelengths. This allows a system to provide concentration(s) of one or more substances in the sample using any number of baseline wavelengths that result in an acceptable accuracy of the determined concentration(s). In other embodiments, systems for detecting a concentration of a substance in a sample of a solution do not need to have emitters and detectors in a 1 : 1 ratio. Examples of systems with other ratios of emitters and detectors are depicted in Figs. 3E and 3F.

[0079] Fig. 3E depicts another system 208 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 208 includes the controller 220, the first detector 250, and the second detector 252, similar to the system 204. However, the first and second emitters 230 and 232 from the system 204 have been combined in the system 208 as a single emitter 236. The single emitter 236 is configured to emit electromagnetic energy in the first range of

wavelengths and in the second range of wavelengths. The electromagnetic energy emitted from the emitter 236 is directed via optical paths through the solution to the first and second detectors 250 and 252. The first and second photodetectors 260 and 262 are configured to detect intensities of the electromagnetic energy received through the solution in the first and second ranges of wavelengths, respectively, as they are received by the first and second detectors 250 and 252. The emitter 236 includes the first and second feedback detectors 240 and 242 configured to detect intensities of the electromagnetic energy emitted by the emitter 236 in the first and second ranges of wavelengths, respectively.

[0080] In one particular example of the system 208 shown in Fig. 3E, the first

wavelength is 260 nm, the second wavelength is 295 nm, the first range of wavelengths is about 240 nm to about 280 nm, and second range of wavelengths is about 275 nm to about 315 nm. Both of the first and second wavelengths are in the UV spectrum, with the first wavelength being in the UVC range (i.e., between about 100 nm and about 280 nm) and the second wavelength being in the UVB range (i.e., between about 280 nm and about 315 nm). In this example, the emitter 236 may be a UVB and UVC emitter configured to emit electromagnetic energy across the UVB range and across the UVC range. The first and second photodetectors 260 and 262 are configured to detect electromagnetic energy only within the first range of wavelengths (from about 240 nm to about 280 nm) and only within the second range of wavelengths (from about 275 nm to about 315 nm), respectively.

[0081] Fig. 3F depicts another system 210 that is configured to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system 210 includes the controller 220, the first emitter 230, and the second emitter 232, the first feedback detector 240, and the second feedback detector, similar to the system 204. However, the first and second detectors 250 and 252 from the system 204 have been combined in the system 208 as a single detector 256. The first and second emitters 230 and 232 are configured to emit electromagnetic energy in the first range of wavelengths and in the second range of wavelengths, respectively. The

electromagnetic energy emitted from the first and second emitters 230 and 232 is directed via optical paths through the solution to the single detector 256. The detector 256 includes the first and second photodetectors 260 and 262 that are configured to detect intensities of the electromagnetic energy received through the solution at least in the first and second ranges of wavelengths, respectively, as they are received by the detector 256. The first and second emitters 230 and 232 include the first and second feedback detectors 240 and 242 configured to detect intensities of the electromagnetic energy emitted by the first and second emitters 230 and 232, respectively.

[0082] In one particular example of the system 210 shown in Fig. 3F, the first wavelength is 260 nm, the second wavelength is 295 nm, the first range of wavelengths is about 245 nm to about 275 nm, and second range of wavelengths is about 280 nm to about 310 nm. Both of the first and second wavelengths are in the UV spectrum, with the first wavelength being in the UVC range and the second wavelength being in the UVB range. In this example, the first emitter 230 may be configured to emit

electromagnetic energy only within the first range of wavelengths (from about 245 nm to about 275 nm) and the second emitter 232 may be configured to emit electromagnetic energy only within the second range of wavelengths (from about 280 nm to about 310 nm). The detector 256 may be configured to detect electromagnetic energy across the UVB range and across the UVC range. For example, the photodetector 260 may be a UVC photodetector configured to detect electromagnetic energy across the UVC range and the photodetector 262 may be a UVB photodetector configured to detect electromagnetic energy across the UVB range.

[0083] The embodiments depicted in Figs. 3E and 3F include examples of the system 208 with a 1 :2 ratio of emitters to detectors and the system 210 with a 2: 1 ratio of emitters to detectors. It will be noted that these ratios may be varied to provide any ratio of emitters and detectors. In some embodiments, a system may include one of a 1 :3 ratio of emitters to detectors (e.g., a wide-spectrum emitter with three narrow-band detectors), a 3: 1 ratio of emitters to detectors (e.g., three narrow-band emitters with a wide-spectrum detector), a 3:2 ratio of emitters to detectors (e.g., two narrow-band UV emitters, one narrow-band visible light emitter, one wide-spectrum UV detector, and one wide-spectrum visible light detector), or any other such ratio.

[0084] In some instances, it may be useful for the systems described herein to be submerged in the solution being tested. Depicted in Fig. 4 is an embodiment of a submergible concentration sensor 310. The submergible concentration sensor 310 includes the system 204. While the embodiment of the submergible concentration sensor 310 includes the system 204, it will be understood that the system 204 in the submergible concentration sensor 310 could be replaced by any of the other systems described herein. The submergible concentration sensor 310 also includes a

housing 312, a first port 314 in the housing 312, and a second port 316 in the

housing 312. In some embodiments, the housing 312, the first port 314, and the second port 316 are arranged together such that, when the submergible concentration sensor 310 is submerged in a solution, the housing 312, the first port 314, and the second port 316 prevent the solution from reaching the system 204.

[0085] In the embodiment depicted in Fig. 4, the first port 314 and the second port 316 are arranged so that the optical paths from the first and second emitters 230 and 232 to the first and second detectors 250 and 252 pass through the first and second ports 314 and 316. The first and second ports 314 and 316 are made from a material that is substantially nonabsorptive of the electromagnetic energy emitted by the first and second emitters 230 and 232. The housing 312, the first port 314, and the second port 316 are further arranged so that, when the submergible concentration sensor 310 is submerged in the solution, a sample of the solution is located between the first and second ports 314 and 316. In this way, when the submergible concentration sensor 310 is submerged in the solution, the electromagnetic energy emitted by the first and second emitters 230 and 232 passes through the first port 314, through the sample of the solution, and through the second port 316 before being detected by the first and second detectors 250 and 252.

[0086] The submergible concentration sensor 310 can be used in a ware washing stations to automatically detect the concentration of a substance in a solution. Fig. 5 depicts an embodiment of a ware washing station 300 that includes the sink 100 and the concentration sensor 310. More specifically, the concentration sensor 310 is mounted inside of the bay 108 so that the concentration sensor 310 is submerged in the aqueous solution 1 18. In this particular embodiment, the aqueous solution 1 18 is a solution of quaternary ammonium compound sanitizer in water and the concentration sensor 310 is configured to detect the concentration of the quaternary ammonium compound in the aqueous solution 1 18.

[0087] In some embodiments, the controller 220 in the concentration sensor 310 is configured to activate an alert in response to determining that the concentration of the quaternary ammonium compound in the aqueous solution 1 18 is not within a particular range. In the depicted embodiment, the ware washing station 300 includes an alert device 320 in the form of a warning light. When the controller 220 detects that the concentration of the quaternary ammonium compound falls outside of the particular range, the controller 220 may send a signal to the alert device 320 to cause the alert device 320 to signal an alert. For example, when the alert device 320 receives the signal from the controller 220, it may illuminate either constantly or intermittently to signal to an operator that the concentration of the quaternary ammonium compound is not correct. This may signal the operator to add additional sanitizer to the aqueous solution 1 18 or replace the aqueous solution 1 18 in the bay 108. One advantage to this type of alert device 320 is that minimal training is needed for an operator to understand the operator needs to change the amount of sanitizer in the aqueous solution 1 18 when the warning light is illuminated.

[0088] The visual alert provided by the warning light is one example of an alert that can be activated by the controller 220, the controller 220 may be configured to activate other types of alerts. The controller 220 may be configured to activate other forms of visual alerts, such as an alert on a computer display screen, an alert displayed on an operator's mobile computing device, or other visual alerts. In these examples, the alert device 320 may be the computer display screen, the operator's mobile device, or any other visual device. The controller 220 may be configured to activate audio alerts, such as a beeping sound produced intermittently, a spoken message to change or replace the aqueous solution 1 18, or any other audio alert. In these examples, the alert device 320 may be a speaker, a siren, or any other audio device. The controller 220 may be configured to activate communication alerts, such as an email, a text message, or an instant message to an operator at the ware washing station 300, an email, a text message, or an instant message to a manager of the operator of the ware washing station 300, or any other communication alert. In these examples, the alert device 320 may be a computing device configured to send the communication alert.

[0089] As noted above, the controller 220 is in communication with the alert device 320. In some embodiments, the controller 220 may be in direct communication with the alert device 320. For example, in the embodiment shown in Fig. 5, the controller 220 may be in direct communication with the alert device 320 via a direct communication interface, such as wireless Bluetooth connection, a wired serial connection, or any other direct connection. In other embodiments, the controller 220 may be in indirect communication with the alert device 320. For example, each of the controller 220 and the alert device 320 may be communicatively coupled to a WiFi router and the controller 220 is configured to send a signal to the WiFi router that is routed by the WiFi router to the alert device 320. In another example, the controller 220 may be in indirect

communication with the alert device 320 via a remote computing device. For example, the controller 220 may send a signal to the remote computing device indicating that the concentration of the quaternary ammonium compound in the aqueous solution 1 18 is not within an acceptable range. The remote computing device is configured to send a signal to the alert device 320 to provide the alert. In one example, in response to receiving the signal from the controller 220 indicating that the concentration of the quaternary ammonium compound in the aqueous solution 1 18 is not within an acceptable range, the remote computing device sends a communication alert (e.g., an email message, a text message, etc.) to the alert device 320 (e.g., a mobile device of the operator or the operator's manager). In some embodiments, the controller 220, the remote computing device, and the alert device 320 are communicatively coupled to each other by one or more networks, such as a WiFi network, a local area network, the internet, a cellular telephone network, or any other wired or wireless network.

[0090] One concern with the systems described herein is the amount of electrical energy required to power the components of the systems. For example, in the concentration sensor 310 shown mounted to the bay 108 in Fig. 5, the power source 224 in the controller 220 may be a battery that provides power to the computing device 222, the communications interface 226, the first emitter 230, the second emitter 232, the first detector 250, and the second detector 252. If each of those components was powered on a constant basis, the electrical energy consumed by the components can deplete the battery relatively quickly. This would require removal of the concentration sensor 310 from the bay 108 to recharge or replace the battery on a frequent basis.

[0091] One way to reduce the rate of electrical consumption by the concentration sensor 310 is for the controller 220 to activate the components intermittently. In particular, the controller 220 can activate each of the emitters for an active period of time and inactivate each of the emitters for an inactive period of time. These active and inactive periods of time can be repeated periodically so that the controller 220 makes periodic determinations whether the concentration of the substance in the sample is within a particular range. This periodic activation can prolong the life of the power source 224 (e.g., battery) in the concentration sensor 310. Another way to reduce the rate of electrical consumption by the concentration sensor 310 is for the controller 220 to activate the components only when the concentration sensor 310 is submerged in the solution. In some embodiments, the concentration sensor 310 may have a conductivity probe that produces a signal indicative of whether the concentration sensor 310 is submerged in a solution. If the conductivity probe signals that the concentration sensor 310 is submerged in a solution, the controller 220 powers the other components of the concentration sensor 310 (e.g., on an intermittent basis). If the conductivity probe signals that the concentration sensor 310 is not submerged in a solution, the

controller 220 stops powering the other components of the concentration sensor 310.

[0092] In some embodiments, the timing of the period activation is selected to produce particular results. In one example, if the concentration of the substance in the solution is expected to change frequently, the inactive periods of time can be shortened so that a determination of the concentration during each of the active periods occurs more frequently to identify frequent changes. In another example, if the concentration of the substance in the solution is expected to change infrequently, the inactive periods of time can be lengthened so that a determination of the concentration during each of the active periods occurs less frequently to reduce energy consumption. In some embodiments, the active periods of time may not produce accurate results during the initial time of the active period (e.g., a "warmup" period of time), and the length of the active periods can be selected to ensure that the active period of time is longer than the warmup period of time. For example, the warmup period of time may be about 5 seconds and the active period of time may be about 20 seconds. In some embodiments, the inactive periods of time may not be uniform. For example, the inactive periods of time may be relatively short (e.g., about 20 to 30 seconds) between the first five active cycles, and a relatively longer inactive period (e.g., 10 minutes) may follow the fifth active cycle. The longer inactive period may be followed by another five active cycles having relatively short inactive periods, followed by another longer inactive period, and so forth. In this last example, data generated during the first active period of each set of five active periods can be discarded from consideration as the data obtained during the first active period after a long inactive period may be unreliable.

[0093] Depicted in Figs. 6A and 6B are charts showing signals generated from detectors and feedback detectors in a system that is usable to detect a concentration of a quaternary ammonium compound in a sample of a solution. The system used to obtain the data in Figs. 6A and 6B was similar to the system 206 depicted in Fig. 3D. In particular, the first emitter 230 emitted electromagnetic energy in a first range of UV wavelengths that included 265 nm, the second emitter 232 emitted electromagnetic energy in a second range of visible wavelengths that included 500 nm, and the third emitter 234 emitted electromagnetic energy in a third range of UV wavelengths that included 295 nm. The first detector 250 was a UV detector, the second detector 252 was a visible light detector, and the third detector 254 was UV detector.

[0094] As can be seen in Figs. 6A and 6B, all of the emitters were initially inactive. At about 8 seconds, the controller 220 activated the first, second, and third detectors 250, 252, and 254 and the first and second emitters 230 and 232. From about 8 seconds to about 26 seconds, the first and second detectors 250 and 252 generated signals indicating intensities of electromagnetic energy received by the first and second detectors 260 and 262 in the first and second ranges of wavelengths, respectively. The first and second feedback detectors 240 and 242 also generated signals indicating intensities of electromagnetic energy emitted by the first and second emitters 230 and 232. During this time, the third detector 254 also generates signals indicating some minor intensity of electromagnetic energy received even though the third emitter 234 was not activated. These signals were likely due to crosstalk from the electromagnetic energy emitted by the first emitter 230 and the data from the third detector 254 during this time can be ignored by the controller 220.

[0095] At about 26 seconds, the controller 220 inactivated the first and second emitters 230 and 232 and activated the third emitter 234. From about 26 seconds to about 44 seconds, the third detector 254 generated signals indicating intensity of electromagnetic energy received by the third detector 264 in the third range of wavelengths. The third feedback detector 244 also generated signals indicating intensity of electromagnetic energy emitted by the third emitter 234. During this time, the first and second detectors 250 and 252 also generated signals indicating some minor intensity of electromagnetic energy received even though the first and second emitters 230 and 232 were not activated. The signals generated by the first

detector 250 were likely due to crosstalk from the electromagnetic energy emitted by the third emitter 234 and the signals from the second detector 252 were likely due to ambient visible light. The data from the first and second detectors 250 and 252 during this time can be ignored by the controller 220. At about 44 seconds, the controller 220 inactivated the third emitter 234 and inactivated the first, second, and third

detectors 250, 252, and 254. From about 44 seconds to about 98 seconds, the system remained in an inactive state.

[0096] At about 98 seconds, the cycle that started at about 8 seconds was repeated again by the controller 220 activating the first, second, and third detectors 250, 252, and 254 and the first and second emitters 230 and 232. This second cycle proceeded in similar manner to the first cycle. The charts shown in Figs. 6A and 6B shows these cycles repeating a number of times, with the time between the starts of the cycles being about 90 seconds.

[0097] In some embodiments, such as that depicted in the charts in Figs. 6A and 6B, at least two emitters are activated at different times. In these embodiments, the controller 220 can extract sets of data from the signals in order to determine a concentration of a substance in the solution. For example, when determining a concentration of a substance in the solution using the data shown in Figs. 6A and 6B, the controller 220 can extract a first set of data from the signals received from the first detector 250 corresponding to the time between about 8 seconds and about 26 seconds, extract a second set of data from the signals received from the second detector 252 corresponding to the time between about 8 seconds and about 26 seconds, and extract a third set of data from the signals received from the third detector 254 corresponding to the time from about 26 seconds and about 44 seconds. The controller 220 can then use these first, second, and third sets of data to determine a concentration of a substance in the solution.

[0098] Depicted in Figs. 7A and 7B are charts with the same data depicted in the charts in Figs. 6A and 6B, except that the charts in Figs. 7A and 7B show data up to 150 seconds. The charts shown in Figs. 7A and 7B also indicate certain periods of time of the collected data. The collected data shown in Figs. 7A and 7B includes a first cycle 400 that includes the time from about 8 seconds to about 98 seconds. The first cycle 400 includes a first active period of time 410, a second active period of time 420, and an inactive period of time 430. During the first active period of time 410, the first, second, and third detectors 250, 252, and 254 and the first and second emitters 230 and 232 were active. During the second active period of time 420, the first, second, and third detectors 250, 252, and 254 and the third emitter 234 were active. During the inactive period of time 430, the first, second, and third emitters 230, 232, and 234 and the first, second, and third detectors 250, 252, and 254 were inactivate.

[0099] The collected data shown in Figs. 7 A and 7B also includes a portion of a second cycle 440 that starts at about 98 seconds. The second cycle 440 includes a first active period of time 450, a second active period of time 460, and an inactive period of time 470. During the first active period of time 450, the first, second, and third detectors 250, 252, and 254 and the first and second emitters 230 and 232 were active. During the second active period of time 460, the first, second, and third detectors 250, 252, and 254 and the third emitter 234 were active. During the inactive period of time 470, the first, second, and third emitters 230, 232, and 234 and the first, second, and third detectors 250, 252, and 254 were inactivate.

[00100] As described above, the data gathered during an initial warmup period of an active period of time may not provide accurate results. In one example, in an initial warmup period 412 of the first active period 410, the data from the first detector 250 is ramping up and the data from the second detector 252 is ramping down. In another example, in an initial warmup period 422 of the second active period 420, the data from the third detector 254 is ramping up. In another example, in an initial warmup period 452 of the first active period 450, the data from the first detector 250 is ramping up and the data from the second detector 252 is ramping down. In another example, in an initial warmup period 462 of the second active period 460, the data from the third detector 254 is ramping up. When the controller 220 determines a concentration of a substance in a solution based on the signals from the first, second, and third

detectors 250, 252, and 254 and the first, second, and third feedback detectors 240, 242, and 244, the controller 220 can extract sets data from the active periods of time that do not include the data from the warmup periods. For example, when extracting the data from the first active period 410 for use in determining a concentration of the substance in the solution, the controller 220 can extract a set of data from the first active period 410 that does not include the warmup period 412 of the first active period 410. Similarly, when extracting the data from the second active period 420 for use in determining a concentration of the substance in the solution, the controller 220 can extract a set of data from the second active period 420 that does not include the warmup period 422 of the second active period 420.

[00101] The collected data and the active, inactive, and warmup periods of time indicated in Figs. 7 A and 7B are one example of how a controller can interpret data. In other examples, controllers can define the active, inactive, and warmup periods in different ways and extract data sets accordingly. In other embodiments, different data can be generated by detectors and feedback detectors. With different data, the active, inactive, and warmup periods may also be defined differently. In some embodiments, controllers are programmed to automatically define active, inactive, and warmup periods without operator intervention. In some embodiments, an operator may define

parameters that are used by controllers to automatically define active, inactive, and warmup periods.

[00102] Fig. 8 depicts an example embodiment of a system 510 that may be used to implement some or all of the embodiments described herein. In the depicted embodiment, the system 510 includes computing devices 520i, 5202, 5203, and 520₄ (collectively computing devices 520). In the depicted embodiment, the computing device 520i is a tablet, the computing device 5202 is a mobile phone, the computing device 5203 is a desktop computer, and the computing device 520₄ is a laptop computer. In other embodiments, the computing devices 520 include one or more of a desktop computer, a mobile phone, a tablet, a phablet, a notebook computer, a laptop computer, a distributed system, a gaming console (e.g., Xbox, Play Station, Wii), a watch, a pair of glasses, a key fob, a radio frequency identification (RFID) tag, an ear piece, a scanner, a television, a dongle, a camera, a wristband, a wearable item, a kiosk, an input terminal, a server, a server network, a blade, a gateway, a switch, a processing device, a processing entity, a set-top box, a relay, a router, a network access point, a base station, any other device configured to perform the functions, operations, and/or processes described herein, or any combination thereof.

[00103] The computing devices 520 are communicatively coupled to each other via one or more networks 530 and 532. Each of the networks 530 and 532 may include one or more wired or wireless networks (e.g., a 3G network, the Internet, an internal network, a proprietary network, a secured network). The computing devices 520 are capable of communicating with each other and/or any other computing devices via one or more wired or wireless networks. While the particular system 510 in Fig. 8 depicts that the computing devices 520 communicatively coupled via the network 530 include four computing devices, any number of computing devices may be communicatively coupled via the network 530.

[00104] In the depicted embodiment, the computing device 5203 is

communicatively coupled with a peripheral device 540 via the network 532. In the depicted embodiment, the peripheral device 540 is a scanner, such as a barcode scanner, an optical scanner, a computer vision device, and the like. In some

embodiments, the network 532 is a wired network (e.g., a direct wired connection between the peripheral device 540 and the computing device 5203), a wireless network (e.g., a Bluetooth connection or a WiFi connection), or a combination of wired and wireless networks (e.g., a Bluetooth connection between the peripheral device 540 and a cradle of the peripheral device 540 and a wired connection between the peripheral device 540 and the computing device 5203). In some embodiments, the peripheral device 540 is itself a computing device (sometimes called a "smart" device). In other embodiments, the peripheral device 540 is not a computing device (sometimes called a "dumb" device).

[00105] Depicted in Fig. 9 is a block diagram of an embodiment of a computing device 600. Any of the computing devices 520 and/or any other computing device described herein may include some or all of the components and features of the computing device 600. In some embodiments, the computing device 600 is one or more of a desktop computer, a mobile phone, a tablet, a phablet, a notebook computer, a laptop computer, a distributed system, a gaming console (e.g. , an Xbox, a Play Station, a Wii), a watch, a pair of glasses, a key fob, a radio frequency identification (RFID) tag, an ear piece, a scanner, a television, a dongle, a camera, a wristband, a wearable item, a kiosk, an input terminal, a server, a server network, a blade, a gateway, a switch, a processing device, a processing entity, a set-top box, a relay, a router, a network access point, a base station, any other device configured to perform the functions, operations, and/or processes described herein, or any combination thereof. Such functions, operations, and/or processes may include, for example, transmitting, receiving, operating on, processing, displaying, storing, determining, creating/generating, monitoring, evaluating, comparing, and/or similar terms used herein. In one embodiment, these functions, operations, and/or processes can be performed on data, content, information, and/or similar terms used herein.

[00106] In the depicted embodiment, the computing device 600 includes a processing element 605, memory 610, a user interface 615, and a communications interface 620. The processing element 605, memory 610, a user interface 615, and a communications interface 620 are capable of communicating via a communication bus 625 by reading data from and/or writing data to the communication bus 625. The computing device 600 may include other components that are capable of

communicating via the communication bus 625. In other embodiments, the computing device does not include the communication bus 625 and the components of the computing device 600 are capable of communicating with each other in some other way.

[00107] The processing element 605 (also referred to as one or more processors, processing circuitry, and/or similar terms used herein) is capable of performing operations on some external data source. For example, the processing element may perform operations on data in the memory 610, data receives via the user interface 615, and/or data received via the communications interface 620. As will be understood, the processing element 605 may be embodied in a number of different ways. In some embodiments, the processing element 605 includes one or more complex

programmable logic devices (CPLDs), microprocessors, multi-core processors, co processing entities, application-specific instruction-set processors (ASIPs),

microcontrollers, controllers, integrated circuits, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), hardware accelerators, any other circuitry, or any combination thereof. The term circuitry may refer to an entirely hardware embodiment or a combination of hardware and computer program products. In some embodiments, the processing element 605 is configured for a particular use or configured to execute instructions stored in volatile or nonvolatile media or otherwise accessible to the processing element 605. As such, whether configured by hardware or computer program products, or by a combination thereof, the processing element 605 may be capable of performing steps or operations when configured accordingly.

[00108] In an illustrative embodiment, the processing element 605 can be used to conserve power of the system by cycling the LEDs (or other light sources) on/off. This helps to conserve the battery in a portable system and reduce the amount of power used by a system that receives power from the grid. The light sources can be triggered on/off according to a periodic schedule, randomly, and/or responsive to user input. An algorithm for controlling the light source triggering can be stored in the memory 610.

[00109] In another illustrative embodiment, the processing element 605 is configured to perform filtering of the solution to remove the effects of any air bubbles that are present. As known in the art, air bubbles will affect the transmission of light from the light source through the solution, resulting in incorrect concentration data for the solution. The processing element 605 can use digital signal processing (DSP) techniques to remove the effects of air bubbles in the light pathways. In addition, any other software or other techniques may also be used by the processing element 605 to remove the impact of air bubbles during concentration determination. In an illustrative embodiment, a mechanical filter can also be incorporated into the system and used to remove/eliminate air bubbles from the solution. The mechanical filter can be used in addition to DSP/software, or alternative to the DSP/software, depending on the embodiment. Any type of mechanical filter known in the art may be used.

[00110] The memory 610 in the computing device 600 is configured to store data, computer-executable instructions, and/or any other information. In some embodiments, the memory 610 includes volatile memory (also referred to as volatile storage, volatile media, volatile memory circuitry, and the like), non-volatile memory (also referred to as non-volatile storage, non-volatile media, non-volatile memory circuitry, and the like), or some combination thereof.

[00111] In some embodiments, volatile memory includes one or more of random access memory (RAM), dynamic random access memory (DRAM), static random access memory (SRAM), fast page mode dynamic random access memory (FPM DRAM), extended data-out dynamic random access memory (EDO DRAM),

synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), double data rate type two

synchronous dynamic random access memory (DDR2 SDRAM), double data rate type three synchronous dynamic random access memory (DDR3 SDRAM), Rambus dynamic random access memory (RDRAM), Twin Transistor RAM (TTRAM), Thyristor RAM (T-RAM), Zero-capacitor RAM (Z-RAM), Rambus in-line memory module (RIMM), dual in-line memory module (DIMM), single in-line memory module (SIMM), video random access memory (VRAM), cache memory (including various levels), flash memory, any other memory that requires power to store information, or any combination thereof.

[00112] In some embodiments, non-volatile memory includes one or more of hard disks, floppy disks, flexible disks, solid-state storage (SSS) (e.g., a solid state drive (SSD)), solid state cards (SSC), solid state modules (SSM), enterprise flash drives, magnetic tapes, any other non-transitory magnetic media, compact disc read only memory (CD ROM), compact disc-rewritable (CD-RW), digital versatile disc (DVD), Blu- ray disc (BD), any other non-transitory optical media, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory (e.g., Serial, NAND, NOR, and/or the like), multimedia memory cards (MMC), secure digital (SD) memory cards, Memory Sticks, conductive-bridging random access memory (CBRAM), phase-change random access memory (PRAM), ferroelectric random-access memory (FeRAM), non-volatile random access memory (NVRAM), magneto-resistive random access memory (MRAM), resistive random-access memory (RRAM), Silicon Oxide-Nitride-Oxide-Silicon memory (SONOS), floating junction gate random access memory (FJG RAM), Millipede memory, racetrack memory, any other memory that does not require power to store information, or any combination thereof.

[00113] In some embodiments, memory 610 is capable of storing one or more of databases, database instances, database management systems, data, applications, programs, program modules, scripts, source code, object code, byte code, compiled code, interpreted code, machine code, executable instructions, or any other information. The term database, database instance, database management system, and/or similar terms used herein may refer to a collection of records or data that is stored in a computer-readable storage medium using one or more database models, such as a hierarchical database model, network model, relational model, entity relationship model, object model, document model, semantic model, graph model, or any other model.

[00114] The user interface 615 of the computing device 600 is in communication with one or more input or output devices that are capable of receiving inputs into and/or outputting any outputs from the computing device 600. Embodiments of input devices include a keyboard, a mouse, a touchscreen display, a touch sensitive pad, a motion input device, movement input device, an audio input, a pointing device input, a joystick input, a keypad input, peripheral device 540, foot switch, and the like. Embodiments of output devices include an audio output device, a video output, a display device, a motion output device, a movement output device, a printing device, and the like. In some embodiments, the user interface 615 includes hardware that is configured to communicate with one or more input devices and/or output devices via wired and/or wireless connections.

[00115] The communications interface 620 is capable of communicating with various computing devices and/or networks. In some embodiments, the

communications interface 620 is capable of communicating data, content, and/or any other information, that can be transmitted, received, operated on, processed, displayed, stored, and the like. Communication via the communications interface 620 may be executed using a wired data transmission protocol, such as fiber distributed data interface (FDDI), digital subscriber line (DSL), Ethernet, asynchronous transfer mode (ATM), frame relay, data over cable service interface specification (DOCSIS), or any other wired transmission protocol. Similarly, communication via the communications interface 620 may be executed using a wireless data transmission protocol, such as general packet radio service (GPRS), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), CDMA2000 1X (1xRTT), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile

Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term

Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Evolution-Data Optimized (EVDO), High Speed Packet Access (HSPA), High-Speed Downlink Packet Access (HSDPA), IEEE 802.1 1 (WiFi), WiFi Direct, 802.16 (WiMAX), ultra wideband (UWB), infrared (IR) protocols, near field communication (NFC) protocols, Wibree, Bluetooth protocols, wireless universal serial bus (USB) protocols, or any other wireless protocol.

[00116] As will be appreciated by those skilled in the art, one or more components of the computing device 600 may be located remotely from other components of the computing device 600 components, such as in a distributed system. Furthermore, one or more of the components may be combined and additional components performing functions described herein may be included in the computing device 600. Thus, the computing device 600 can be adapted to accommodate a variety of needs and circumstances. The depicted and described architectures and descriptions are provided for exemplary purposes only and are not limiting to the various embodiments described herein.

[00117] Also described herein are systems and methods for measuring the concentration of a solution, such as a quaternary ammonium solution, through electrochemical techniques without the use of UV light. Fig. 10 is a block diagram of a device 700 that uses an electrochemical technique to measure the concentration of a compound present in a solution in accordance with embodiments described herein. The device 700 includes a working electrode 705, a reference electrode 710, a counter electrode 715, a potentiostat 720, one or more sensors 725, and a controller 730. In alternative embodiments, the device 700 may include fewer, additional, and/or different components. The device 700 is configured to use an electrochemical technique, such as voltammetry or amperometry, to determine concentration of a compound in a solution. In an illustrative embodiment, the compound is quaternary ammonium compound and the solution is a mixture of quaternary ammonium compound and water. Alternatively, the device 700 can be used with other compounds and solutions. For example, as discussed in more detail below, the device 700 can be used to measure and monitor the concentration of hydrogen peroxide.

[00118] As depicted in Fig. 10, the device 700 includes three electrodes in an illustrative embodiment, the working electrode 705, the reference electrode 710, and the counter electrode 715. In an alternative embodiment, the device 700 may be

implemented with only the working electrode 705 and the reference electrode 710, and the counter electrode 715 may not be included. The electrodes can be made from a variety of materials such as carbon, platinum, gold, silver, etc. In an illustrative embodiment, the working electrode 705 and the counter electrode 715 are screen- printed carbon electrodes, and the reference electrode 710 is a silver/silver chloride (Ag/AgCI) electrode. In alternative embodiments, different materials and/or fabrication techniques may be used for the electrodes. [00119] The potentiostat 720 is used to generate a potential (i.e., a voltage) and to apply the generated potential to the working electrode 705. The potentiostat 720 can be electrically connected to the working electrode 705 through a wired connection. Any type of potentiostat known in the art may be used. The sensor(s) 725 include one or more sensors to directly or indirectly measure electrical properties of the solution, such as current, conductivity, voltage, impedance, etc. The sensor(s) 725 are discussed in more detail below. The controller 730 is used to conduct concentration determinations, and include any type of processing/controlling components known in the art. For example, the controller 730 can include a processor, microprocessor, microcontroller, etc. The controller 730 can also include a memory to store algorithms, software, thresholds, and other operating instructions, a transceiver for communication, an alert system to inform a user of measurement results, etc. The controller 730 may also include an interface that enables a device operator to interact with and control the device 700. The interface of the controller 730 can include a touchscreen, one or more light/sound indicators, a keyboard, a mouse, a speaker, a microphone, etc.

[00120] In an illustrative embodiment, the controller 730 of the device utilizes the working electrode 705, the reference electrode 710, the counter electrode 715, the potentiostat 720, and the sensor(s) 725 to determine a concentration. Specifically, the potentiostat 720 is electrically coupled to the working electrode 705 and is controlled by the controller 730 to supply a desired potential in increments to the working electrode 705. The desired potential is relative to a voltage at the reference electrode 710. The desired potential can be an incremental range, such as from -400 millivolts (mV) to 1300 mV. In alternative embodiments, other ranges can be used such as -600 mV- 1300 mV, -600 mV - 1500 mV, 0 mV - 1300 mV, -400 mV - 1000 mV, etc. The increments of supplied potential can be 100 mV increments in one embodiment.

Alternatively, other increments can be used such as 5 mV, 10 mV, 25 mV, 50 mV, 200 mV, etc. The potential supplied to the working electrode 705 causes a current flow between the working electrode 705 and the counter electrode 715. [00121] For solutions containing a compound that oxidizes or reduces in response to an applied potential, the controller 730 uses the sensor(s) to measure current flow between the working electrode 705 and the counter electrode 715 at each of the increments of potential supplied to the working electrode 705 by the potentiostat 720. In such solutions, the current flow is proportional to the compound concentration and can be used to determine concentration in a straightforward manner. However, current alone is not always sufficient to determine compound concentration because some compounds, such as quaternary ammonium compound, do not oxidize or reduce in the potential range suitable for aqueous environments. Thus, the applied potential does not necessarily result in a flow of electrons that can be measured as a current. As a result, other electrical properties such as conductivity or impedance can be used along with electrochemical techniques such as voltammetry or amperometry to determine concentration.

[00122] As an example, amperometric techniques can be performed by producing a charging current in the solution using the potentiostat 720 or another current generating component. The magnitude of the generated charging current depends in part on the conductivity of the solution being tested and in part on the magnitude of the potential step. It is also known that an increasing quaternary ammonium concentration increases the conductivity of the solution. As a result, the charging current that is measured increases with increasing compound concentration and can be correlated to the concentration via conductivity measurements or determinations. However, the increases in charging current caused by the compound in the solution are small, and can be affected by minute changes in water hardness and other properties of the water used to form the solution.

[00123] In an illustrative embodiment, at least one of the sensor(s) 725 is used to determine a conductivity, impedance, and/or other properties of the water (or other liquid) used to form the solution with the compound. The controller 730 is then able to subtract (i.e., disregard) contributions to the conductivity/impedance from the water that is used to form the solution. However, it is possible that the contributions to conductivity/impedance from the water will change over time. For example, the calcium concentration in water can change over time, which will affect the contribution to conductivity/impedance of the solution from the water.

[00124] To account for changes in the water (or other liquid) used to form a solution, the inventors have determined that the current measured after applying the potential to the working electrode 705 for a period of time is not affected by the quaternary ammonium compound concentration. This is important because when other solution parameters change (e.g., calcium concentration), both the initial current and the current after the period of time for which the potential is applied change linearly with the change in condition. Therefore, the change in salt concentration/water hardness can be determined by examining the current after holding the potential for the designated period of time. Once the salt concentration is known, it can be used to subtract the contribution of salt to the current collected immediately after the potential is applied. The remaining (initial) current is attributable to the quaternary ammonium compound concentration, thereby enabling concentration monitoring in solutions where salt concentrations vary over time. In an illustrative embodiment, the period of time can be 2000 milliseconds (ms). Alternatively, other time periods to hold the potential can be used, such as 1500 ms, 1800 ms, 2200 ms, 2500 ms, etc.

[00125] In an illustrative embodiment, the controller 730 is configured to

periodically obtain and store the concentration of salts and other components in the water that affect the current and other electrical properties of the solution. The controller 730 uses this information to subtract the contribution from the water such that the concentration of the compound of interest (e.g., quaternary ammonium compound) can be accurately determined. The device 700 can be used in any context in which it is desirable to determine compound concentration in stationary or flowing solutions, such as a dispenser, a line, a sink, a beaker, etc. The device 700 can be mounted in a container (e.g., a dispenser) or implemented as a handheld portable device, depending on the application. [00126] Fig. 1 1 is a flow diagram depicting operations performed by a device to detect compound concentration in accordance with an illustrative embodiment. In alternative embodiments, fewer, additional, and/or different operations may be performed. Also, the use of a flow diagram is not meant to be limiting with respect to the order of operations performed. In an operation 800, the device tests water prior to using the water to form a solution that includes a compound such as quaternary ammonium compound. The test can be performed with one or more sensors, and is used to determine salt concentration(s) in the water. As discussed above, the salt concentration(s) in the water are taken into consideration because they can affect the apparent concentration of the compound of interest, especially for compounds such as quaternary ammonium compound.

[00127] In an operation 805, the device applies a potential in increments to a formed solution. In an illustrative embodiment, the device uses a potentiostat to apply the potentials to a working electrode. In alternative embodiments, any other source may be used to generate the potential or may apply the potential to the reference electrode. The potential is applied in increments over a range of voltage values, as described herein.

[00128] In an operation 810, the device measures an initial electrical property of the solution responsive to each of the applied potentials. In an illustrative embodiment, each incrementally applied potential causes a current to flow from the working electrode to the counter electrode, and this current can be measured as the initially measured electrical property. The current can be measured using a current sensor of the device, and any current sensor known in the art may be used. In an alternative embodiment, the initially measured (or determined) electrical property can be voltage, conductivity, impedance, etc.

[00129] In an operation 815, the device measures a delayed electrical property of the solution responsive to each of the applied potentials. The delayed electrical property is measured after the electrical potential has been held for a predetermined amount of time. The predetermined amount of time is 2000 ms in an illustrative embodiment, although other values can be used in alternative implementations. As discussed above, the electrical property, such as current, is determined by salts and/or other contaminants in the water (and not the compound of interest) when measured after such a delay. Conversely, the initial measurement of operation 810 includes contributions to the electrical property (e.g., current) from both the compound of interest and the water.

[00130] In an operation 820, the device determines the contribution of the water on the initial measured electrical property based on the test of operation 800 and/or the delayed electrical properties measured in the operation 815. In one embodiment, results of the operation 815 can be compared to results of the operation 800 to determine if the contribution to the initially measured electrical property by the water has changed since the solution was created. If it is determined that the contribution to the electrical property by the water has not changed, the results of the test in operation 800 can be used to determine the contribution of the water to the initially measured electrical property. If it is determined that the contribution to the initially measured electrical property by the water has changed (i.e., the result of operation 815 differs from that of operation 800), the result of the operation 815 is used to determine the overall contribution to the electrical property by the water.

[00131] In an operation 825, the device determines a concentration of a compound in the solution based on the initially measured electrical property (at each increment of the applied potential) and the contribution to the initially measured electrical property by the water (at each increment of the applied potential), as determined in the operation 820. Specifically, the contribution to the initially measured electrical property by the water is subtracted from the initially measured electrical property, which results in just the contribution from the compound of interest to the initially measured electrical property. The contribution from the compound of interest to the initially measured electrical property is then used to determine the concentration of the compound using one or more electrochemical techniques. [00132] Any electrochemical techniques known in the art may be used, such as various forms of voltammetry or amperometry. For example, the device can utilize any combination of the following techniques, depending on the specific compound and application: voltammetry such as linear sweep voltammetry, staircase voltammetry, square wave voltammetry, cyclic voltammetry (i.e., a voltammetric method that can be used to determine diffusion coefficients and half cell reduction potentials), anodic stripping voltammetry (i.e., a quantitative, analytical method for trace analysis of metal cations in which an analyte is deposited (electroplated) onto the working electrode during a deposition step, and then oxidized during a stripping step at which time the current is measured), cathodic stripping voltammetry (i.e., a quantitative, analytical method for trace analysis of anions in which a positive potential is applied, oxidizing a mercury electrode and forming insoluble precipitates of the anions, and in which a negative potential then reduces (strips) the deposited film into solution), adsorptive stripping voltammetry (i.e., a quantitative, analytical method for trace analysis in which an analyte is deposited by adsorption on an (chemically modified) electrode surface without electrolysis and electrolyzed to provide an analytical signal), alternating current voltammetry (i.e., potentiodynamic electrochemical impedance spectroscopy), polarography (i.e., a subclass of voltammetry where the working electrode is a dropping mercury electrode (DME) that is useful for its wide cathodic range and renewable surface), rotated electrode voltammetry (i.e., a hydrodynamic technique in which the working electrode, usually a rotating disk electrode (RDE) or rotating ring-disk electrode (RRDE), is rotated at a very high rate, which is useful for studying the kinetics and electrochemical reaction mechanism for a half reaction), normal pulse voltammetry, differential pulse voltammetry, and/or chronoamperometry.

[00133] Various tests were run to confirm accuracy of the device 700 depicted in Fig. 10 and the process described with reference to Fig. 1 1 . Fig. 12A depicts tests run on various quaternary ammonium compound (QAC) and water dilutions in accordance with embodiments described herein. In Fig. 12A, the x-axis is time (seconds) and the y- axis is current in milliAmps (mA). The various water dilutions include tap water 900, a 1 : 1024 QAC: water dilution 905, a 1 :512 QAC: water dilution 910, and a 1 :256 QAC: water dilution 915. Fig. 12B depicts the effect of calcium concentrations in the water in accordance with the embodiments described herein. In Fig. 12B, the x-axis is time (seconds) and the y-axis is current in mA. A line 920 represents tap water, a line 925 represents 20 mg of Ca present in the solution, a line 930 represents 40 mg of Ca present in the solution, and a line 935 represents 60 mg of Ca present in the solution. Fig. 12C depicts current versus time after 2000 ms of applied potential to a solution in accordance with embodiments described herein. Fig. 12D depicts maximum current versus time resulting from the applied potential to the solution in accordance with embodiments described herein. Fig. 12E depicts current versus time for a solution with 60 mg Ca (plot 940) and a solution with quaternary ammonium compound and 60 mg Ca (plot 945) in accordance with embodiments described herein.

[00134] Figs. 12A-12E demonstrate that increasing quaternary ammonium compound concentrations increase the current that is measured immediately after stepping the potential to 1300 mV. However, the current does not increase when measured after holding the potential for 2000 ms after the step. This is not the case when the concentration of a salt contributing to water hardness (e.g., calcium) increases in concentration. In such a case, the increase is much more dramatic, and the increase is linear at both time points (i.e., immediately after application of the potential and 2000 ms after application of the potential), although they may have different slopes.

Additionally, as discussed, adding quaternary ammonium compound to a solution containing a concentration of salt only affects the current immediately after the step. Therefore, the current collected at 2000 ms can be used to determine salt

concentration, which in turn can predict the contribution of the current from the salt to the peak immediately after the step. With this information, the concentration of quaternary ammonium compound in the solution can be determined as discussed with reference to Fig. 1 1 .

[00135] In an illustrative embodiment, the device 700 of Fig. 10 can also be used to measure the concentration of hydrogen peroxide in a solution. Specifically, the potentiostat 720, which is electrically coupled to the working electrode 705, is used to supply incremental potential voltages to the working electrode 705 over a designated voltage range. For determining hydrogen peroxide concentration, the voltage range can be -400 mV to 1300 mV. Alternatively, a different range of values may be used. The step between increments can be 100 mV or more, 50 mV, 25 mV, 10 mV, 5 mV, etc.

[00136] The applied potentials cause current to flow between the working electrode 705 and the counter electrode 715. Specifically, if the change in potential is sufficient, and if an electrochemically active molecule (e.g., hydrogen peroxide) is present in the solution at the electrode surface, the active molecule undergoes a redox reaction resulting in a flow of electrons that is detectable as an electrical current. This current is measured and recorded at the various steps throughout the applied potential range. The measured current is linearly proportional to the concentration of hydrogen peroxide (or other active) molecules in the solution. As such, the concentration of the electrochemically active molecules in the solution can be readily determined. This device and process can be used for stationary or flowing solutions in any type of container, including a sink, bucket, beaker, dispenser, mixing station, etc.

[00137] The determination of hydrogen peroxide concentration is relatively straightforward compared to the determination of quaternary ammonium compound concentration. This is because most other chemicals are not electrochemically active in the potential range that hydrogen peroxide oxidizes in. Therefore, any electrochemical signal detected in a formulation containing hydrogen peroxide can be attributed to coming from hydrogen peroxide molecules. Additionally, even if hydrogen peroxide is not the main active ingredient in a solution, information about other ingredients in the solution can be inferred if the composition of the solution being tested is known.

Further, the test results indicate that determination of hydrogen peroxide concentration is relatively robust against changes in concentrations of other molecules, such as molecules contributing to water hardness. As discussed above, this is not the case for other techniques such as conductivity measurements. [00138] As an example, a test was performed to measure the concentration of hydrogen peroxide in a solution. In the test, a potential was applied to the working electrode and stepped using amperometry from -400 mV to 1300 mV. In alternative implementations, voltammetry can be used instead of amperometry. In the test device, the working and counter electrodes were made from carbon, and the reference electrode was made from silver chloride. It was shown that hydrogen peroxide begins to oxidize at potentials above 1000 mV, and that the signal becomes stronger as the applied potential is increased in excess of 1000 mV. Additionally, the measured response resulting from the applied potentials is linear.

[00139] Fig. 13A depicts measurements of Oxivinwater dilutions in accordance with embodiments described herein. In Fig. 13A, the x-axis is in milliseconds and the y- axis is in milliamps. Oxivir is a solution that contains hydrogen peroxide. A line 1000 represents water, a line 1005 represents a 1 : 16 dilution, a line 1010 represents a 1 :20 dilution, a line 1015 represents a 1 :40 dilution, a line 1020 represents a 1 :80 dilution, and a line 1025 represents a 1 : 160 dilution. Fig. 13B depicts the linear response of the dilutions from Fig. 13A in accordance with embodiments described herein. In Fig. 13B, the x-axis represents concentration in terms of the dilution (e.g., 1 :20 = 0.05), and the y- axis is current in milliamps. Also in Fig. 13B, point 1030 represents the response of water, point 1035 represents the response of the 1 : 160 dilution, point 1040 represents the response of the 1 :80 dilution, point 1045 represents the response of the 1 :40 dilution, point 1050 represents the response of the 1 :20 dilution, and point 1055 represents the response of the 1 : 16 dilution (which is the normal dilution for Oxivir).

[00140] In the experimental data of Fig. 13, 20 mg of calcium chloride (CaCI) and 20 mg of magnesium chloride (MgCI) were added to the solutions to simulate the conditions of hard water. As shown in the results, the response is linear and can be achieved in varying water conditions. It has been shown that minor changes in solution conditions do not affect the results significantly. However, major changes in solution conditions can potentially generate different sets of calibration curves. These

calibration curves can be pre-loaded into the measuring device (e.g., stored in a memory thereof) and the appropriate calibration can be automatically selected based on the water only response.

[00141] In an illustrative embodiment, any of the devices and techniques described herein can be used to measure and monitor the concentration of a compound in a solution. For example, any of the devices described herein can be used in a mounted device or in a hand-held device. Any of the devices described herein can also be used to measure and monitor compound concentrations in stationary solutions or flowing solutions. In addition to measuring concentrations, any of the devices can also be configured to monitor solution concentration over time, and to alert a user if the measured concentration does not satisfy a predetermined concentration threshold. For example, if the desired compound:water ratio is 1 : 16, the device can alert the user if the measured concentration is less than or greater than 1 : 16 by a predetermined amount (e.g., 1 % less than or greater, 2% less than or greater, 5% less than or greater, 10% less than or greater, etc. depending on the application). The alert can be a visual alert such as an LED indicator, an audio alert such as a sound, a tactile alert such as a vibration, and/or a transmitted alert such as a text message or e-mail sent to a computing device from the measuring device.

[00142] Fig. 14 depicts a dispenser 1 100 in accordance with embodiments described herein. The dispenser 1 100 is in the form of a spray bottle and includes a solution 1 105 in a reservoir that can be dispensed through a dispensing head 1 1 10, which is in the form of a trigger activated spray nozzle. In alternative embodiments, the dispenser 1 100 can be in any other form and can include a different type of dispensing head. The dispenser 1 100 also includes a concentration measurement and monitoring device 1 1 15 that has an incorporated indicator light 1 120. The concentration

measurement and monitoring device 1 1 15 can include any of the components described herein such as a working electrode, a reference electrode, a counter electrode, a potentiostat, a controller, one or more UV emitters, one or more UV detectors, electrical sensors, etc. The concentration measurement and monitoring device 1 1 15 can also include a processor, a memory, a transceiver, a power source, etc.

[00143] The controller (or a memory associated therewith) of the concentration measurement and monitoring device 1 1 15 can include algorithms to perform any of the operations described herein for determining solution concentration. The indicator light 1 120 can be a solution indicator that is used to inform a user of the status of the solution 1 105. In one embodiment, the indicator light 1 120 can display a green light if a determined compound concentration in the solution 1 105 is within the predetermined threshold, and a red light if the concentration of the solution 1 105 is not within the predetermined threshold. Alternatively, any other type of indicator system may be used. Additionally, although the concentration measurement and monitoring device 1 1 15 is depicted at a bottom of the dispenser 1 100, in alternative embodiments the

concentration measurement and monitoring device 1 1 15 may be positioned in the dispensing head 1 1 10, distributed throughout the dispenser 1 100, or positioned elsewhere within the dispenser 1 100.

[00144] Embodiments described herein may be implemented in various ways, including as computer program products that comprise articles of manufacture. A computer program product may include a non-transitory computer-readable storage medium storing applications, programs, program modules, scripts, source code, program code, object code, byte code, compiled code, interpreted code, machine code, executable instructions, and/or the like (also referred to herein as executable

instructions, instructions for execution, computer program products, program code, and/or similar terms used herein interchangeably). Such non-transitory computer- readable storage media include all computer-readable media (including volatile and non-volatile media).

[00145] As should be appreciated, various embodiments of the embodiments described herein may also be implemented as methods, apparatus, systems, computing devices, and the like. As such, embodiments described herein may take the form of an apparatus, system, computing device, and the like executing instructions stored on a computer readable storage medium to perform certain steps or operations. Thus, embodiments described herein may be implemented entirely in hardware, entirely in a computer program product, or in an embodiment that comprises combination of computer program products and hardware performing certain steps or operations.

[00146] Embodiments described herein may be made with reference to block diagrams and flowchart illustrations. Thus, it should be understood that blocks of a block diagram and flowchart illustrations may be implemented in the form of a computer program product, in an entirely hardware embodiment, in a combination of hardware and computer program products, or in apparatus, systems, computing devices, and the like carrying out instructions, operations, or steps. Such instructions, operations, or steps may be stored on a computer readable storage medium for execution buy a processing element in a computing device. For example, retrieval, loading, and execution of code may be performed sequentially such that one instruction is retrieved, loaded, and executed at a time. In some exemplary embodiments, retrieval, loading, and/or execution may be performed in parallel such that multiple instructions are retrieved, loaded, and/or executed together. Thus, such embodiments can produce specifically configured machines performing the steps or operations specified in the block diagrams and flowchart illustrations. Accordingly, the block diagrams and flowchart illustrations support various combinations of embodiments for performing the specified instructions, operations, or steps.

[00147] For purposes of this disclosure, terminology such as "upper," "lower," "vertical," "horizontal," "inwardly," "outwardly," "inner," "outer," "front," "rear," and the like, should be construed as descriptive and not limiting the scope of the claimed subject matter. Further, the use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected," "coupled," and "mounted" and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Unless stated otherwise, the terms "substantially," "approximately," and the like are used to mean within 5% of a target value.

[00148] The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.

Claims

CLAIMS What is claimed is:

1 . A system for detecting a concentration of a substance in a sample, the system comprising:

a first emitter configured to selectively emit electromagnetic energy in a first range of wavelengths via a first optical path in the sample, wherein the first range of wavelengths includes a first wavelength, and wherein the substance is at least partially absorptive of electromagnetic energy at the first wavelength;

a second emitter configured to selectively emit electromagnetic energy in a second range of wavelengths via a second optical path in the sample, wherein the second range of wavelengths includes a second wavelength, and wherein the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength;

a first detector arranged in the first optical path, wherein the first detector is configured to detect electromagnetic energy in the first range of wavelengths;

a second detector arranged in the second optical path, wherein the second detector is configured to detect electromagnetic energy in the second range of wavelengths; and

a controller configured to:

receive signals from the first detector indicative of an intensity of electromagnetic energy received by the first detector in the first range of wavelengths, receive signals from the second detector indicative of an intensity of electromagnetic energy received by the second detector in the second range of wavelengths, and

determine the concentration of the substance in the sample based at least in part on the signals from the first detector and the signals from the second detector.

2. The system of claim 1 , further comprising:

a third emitter configured to selectively emit electromagnetic energy in a third range of wavelengths, wherein the third range of wavelengths includes a third

wavelength, and wherein the substance is substantially nonabsorptive of

electromagnetic energy at the third wavelength; and

a third detector arranged in an optical path of the third emitter, wherein the third detector is configured to detect electromagnetic energy in the third range of

wavelengths;

wherein the controller is further configured to receive signals from the third detector indicative of an intensity of electromagnetic energy received by the third detector in the third range of wavelengths; and

wherein the controller is further configured to determine the concentration of the substance in the sample based at least on the signals from the first detector, the signals from the second detector, and the signals from the third detector.

3. The system of claim 2, wherein:

the first range of wavelengths is within an ultraviolet range of wavelengths;

the second range of wavelengths is within the ultraviolet range of wavelengths; and

the third range of wavelengths is within a visible light range of wavelengths.

4. The system of claim 3, wherein the first detector and the second detector are configured to detect electromagnetic energy across the ultraviolet range of wavelengths, and wherein the third detector is configured to detect electromagnetic energy across the visible light range of wavelengths.

5. The system of claim 4, wherein the first range of wavelengths and the second range of wavelengths do not overlap each other within the ultraviolet range of

wavelengths.

6. The system of claim 1 , wherein the first wavelength is about 260 nm and the second wavelength is about 295 nm.

7. The system of claim 1 , wherein the first range of wavelengths and the second range of wavelengths are at least 40 nanometers (nm).

8. The system of claim 1 , wherein the first range of wavelengths and the second range of wavelengths are at least 20 nanometers (nm).

9. The system of claim 1 , wherein the first range of wavelengths and the second range of wavelengths are at least 10 nanometers (nm).

10. The system of claim 1 , further comprising:

a first feedback detector configured to detect an intensity of the electromagnetic energy emitted by the first emitter; and

a second feedback detector configured to detect an intensity of the

electromagnetic energy emitted by the second emitter.

1 1 . The system of claim 10, wherein the controller is further configured to:

receive signals from the first feedback detector indicative of the intensity of the electromagnetic energy emitted by the first emitter;

receive signals from the second feedback detector indicative of the intensity of the electromagnetic energy emitted by the second emitter; and

determine the concentration of the substance in the sample based at least on a first ratio of the intensity of electromagnetic energy received by the first detector in the first range of wavelengths to the intensity of the electromagnetic energy emitted by the first emitter and a second ratio of the intensity of electromagnetic energy received by the second detector in the second range of wavelengths to the intensity of the electromagnetic energy emitted by the second emitter.

12. The system of claim 1 , wherein the first emitter, the second emitter, the first detector, and the second detector are configured to be submerged in the sample.

13. The system of claim 12, wherein the controller is configured to be submerged in the sample with at least one of the first emitter, the second emitter, the first detector, and the second detector.

14. The system of claim 1 , wherein the controller is configured to make periodic determinations whether the concentration of the substance in the sample is within a particular range.

15. The system of claim 14, wherein the controller is configured to activate an alert in response to one of the periodic determinations being a determination that the

concentration of the substance in the sample is not within the particular range.

16. The system of claim 15, wherein the alert includes one or more of a visual alert, an audio alert, or a communication alert.

17. The system of claim 1 , wherein the controller is further configured to determine the concentration of the substance in the sample based at least on the signals from the first detector and the signals from the second detector based on a difference between the intensity of electromagnetic energy received by the first detector and the intensity of electromagnetic energy received by the second detector.

18. The system of claim 1 , wherein the system is configured to:

activate the first emitter during a first active period of time;

inactivate the first emitter during a first inactive period of time;

activate the second emitter during a second active period of time; and

inactivate the second emitter during a second inactive period of time.

19. The system of claim 18, wherein the controller is further configured to: extract a first set of data from the signals from the first detector, wherein the first set of data is indicative of the intensity of electromagnetic energy received by the first detector during at least a portion of the first active period of time; and

extract a second set of data from the signals from the second detector, wherein the second set of data is indicative of the intensity of electromagnetic energy received by the second detector during at least a portion of the second active period of time; wherein the controller is further configured to determine the concentration of the substance in the sample based at least on the signals from the first detector and the signals from the second detector based on the first set of data and the second set of data.

20. The system of claim 19, wherein:

the portion of the first active period of time does not include a warmup period of the first emitter during the first active period of time; and

the portion of the second active period of time does not include a warmup period of the second emitter during the second active period of time.

21 . The system of claim 18, wherein the first active period of time and the second period of time do not overlap each other.

22. The system of claim 1 , wherein the first emitter is configured to emit

electromagnetic energy only within the first range of wavelengths and wherein the second emitter is configured to emit electromagnetic energy only within the second range of wavelengths.

23. The system of claim 22, wherein the first detector and the second detector are a single detector configured to detect electromagnetic energy in a detection range that encompasses the first and second range of wavelengths.

24. The system of claim 22, wherein the first detector and the second detector are separate detectors, and wherein the first range of wavelengths does not overlap the second range of wavelengths.

25. The system of claim 1 , wherein the first detector is configured to detect

electromagnetic energy only within the first range of wavelengths and wherein the second detector is configured to detect electromagnetic energy only within the second range of wavelengths.

26. The system of claim 25, wherein the first emitter and the second emitter are a single emitter configured to selectively emit electromagnetic energy in an emission range that encompasses the first and second range of wavelengths.

27. The system of claim 25, wherein the first emitter and the second emitter are separate emitters, and wherein the first range of wavelengths does not overlap the second range of wavelengths.

28. The system of claim 1 , wherein the substance is at least partially absorptive of electromagnetic energy at the first wavelength by absorbing at least 50% of

electromagnetic energy at the first wavelength.

29. The system of claim 1 , wherein the substance is substantially nonabsorptive of electromagnetic energy at the second wavelength by permitting transmittance of at least 90% of electromagnetic energy at the second wavelength.

30. A method of detecting a concentration of a substance in a sample, the method comprising:

causing, by a controller, emission of electromagnetic energy from at least one emitter via at least one optical path in the sample, wherein the electromagnetic energy includes electromagnetic energy in a first range of wavelengths that includes a first wavelength and electromagnetic energy in a second range of wavelengths that includes a second wavelength, wherein the substance is at least partially absorptive of electromagnetic energy at the first wavelength, and wherein the substance is

substantially nonabsorptive of electromagnetic energy at the second wavelength;

receiving, by the controller from at least one detector arranged in at least one optical path of the at least one emitter and configured to detect electromagnetic energy in the first and second ranges of wavelengths, signals indicative of an intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths and signals indicative of an intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths; and

determining, by the controller, the controller is further configured to determine the concentration of the substance in the sample based at least on the signals indicative of the intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths and the signals indicative of the intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths.

31 . The method of claim 30, wherein the at least one emitter includes a first emitter configured to emit electromagnetic energy only within the first range of wavelengths and a second emitter configured to emit electromagnetic energy only within the second range of wavelengths, and wherein causing emission of electromagnetic energy from the at least one emitter comprises:

activating, by the controller, the first emitter during a first active period of time; inactivating, by the controller, the first emitter during a first inactive period of time; activating, by the controller, the second emitter during a second active period of time; and

inactivating, by the controller, the second emitter during a second inactive period of time.

32. The method of claim 31 , wherein further comprising:

extracting a first set of data from the signals indicative of an intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths, wherein the first set of data is indicative of the intensity of electromagnetic energy received by the at least one detector in the first range of wavelengths during at least a portion of the first active period of time; and

extract a second set of data from the signals indicative of an intensity of electromagnetic energy received by the at least one detector in the second range of wavelengths, wherein the second set of data is indicative of the intensity of

electromagnetic energy received by the at least one detector in the second range of wavelengths during at least a portion of the second active period of time;

wherein the controller is further configured to determine the concentration of the substance in the sample based at least on the first set of data and the second set of data.

33. The method of claim 32, wherein:

34. The method of claim 30, wherein the at least one emitter includes a first detector configured to detect electromagnetic energy only in the first range of wavelengths and a second detector configured to detect electromagnetic energy only in the second range of wavelengths.

35. The method of claim 34, wherein the first range of wavelengths is within an ultraviolet range of wavelengths, wherein the second range of wavelengths is within the ultraviolet range of wavelengths, and wherein the first range of wavelengths does not overlap the second range of wavelengths.

36. The method of claim 35, wherein the at least one emitter includes a third detector configured to detect electromagnetic energy only in a third range of wavelengths, wherein the third range of wavelengths is within a visible light range of wavelengths, and wherein the substance is substantially nonabsorptive of electromagnetic energy at the third wavelength.

37. The method of claim 30, wherein the causing of the emission of electromagnetic energy from at least one emitter and the receiving of the signals are performed while the at least one emitter and the at least one detector are submerged in the sample.

38. The method of claim 37, wherein the controller is configured to be submerged in the sample with at least one emitter and the at least one detector.

39. The method of claim 30, further comprising:

making, by the controller, periodic determinations whether the concentration of the substance in the sample is within a particular range.

40. The method of claim 39, further comprising:

activating, by the controller, an alert in response to one of the periodic

determinations being a determination that the concentration of the substance in the sample is not within the particular range.

41 . The method of claim 30, wherein the first range of wavelengths and the second range of wavelengths are at least 40 nanometers (nm).

42. The method of claim 30, wherein the first range of wavelengths and the second range of wavelengths are at least 20 nanometers (nm).

43. The method of claim 30, wherein the first range of wavelengths and the second range of wavelengths are at least 10 nanometers (nm).

44. A device for determining a compound concentration, the device comprising: a working electrode configured to be placed in a solution that includes a compound;

a potentiostat electrically connected to the working electrode and configured to deliver a potential to the working electrode;

a sensor configured to detect an initial electrical property resulting from the potential and a delayed electrical property that results after the potential is delivered for a time period; and

a controller configured to determine a concentration of the compound in the solution based at least in part on the initial electrical property and at least in part on the delayed electrical property.

45. The device of claim 44, further comprising a counter electrode.

46. The device of claim 45, wherein the initial electrical property comprises an initial current that flows between the working electrode and the counter electrode.

47. The device of claim 44, further comprising a reference electrode, wherein the potential is relative to the reference electrode.

48. The device of claim 44, wherein the time period comprises 2000 milliseconds.

49. The device of claim 44, wherein the potential comprises a plurality of potentials applied in increments over a voltage range.

50. The device of claim 49, wherein the voltage range comprises -400 millivolts to 1300 millivolts.

51 . The device of claim 49, wherein each increment is 100 millivolts.

52. The device of claim 44, wherein the compound comprises quaternary ammonium compound.

53. The device of claim 44, wherein the controller determines the concentration using voltammetry or amperometry.

54. The device of claim 44, wherein the sensor is configured to determine a salt concentration of water used to form the solution with the compound.

55. The device of claim 54, wherein the controller determines the concentration of the compound based at least in part on the salt concentration of the water used to form the solution.

56. The device of claim 44, further comprising an alarm to alert a user that the concentration of the compound is outside of an acceptable range.

57. The device of claim 44, wherein the controller is configured to determine a salt concentration of the solution based on the delayed electrical property.

58. The device of claim 57, wherein the controller is configured to determine an amount of the initial electrical property caused by the salt concentration of the solution.

59. The device of claim 58, wherein the controller is configured to determine an amount of the initial electrical property caused by the concentration of the compound by subtracting the amount of the initial electrical property caused by the salt concentration from the initial electrical property.

60. The device of claim 59, wherein the controller determines the concentration of the compound based on the amount of the initial electrical property caused by the concentration of the compound.

61 . A device for determining a compound concentration, the device comprising:

a working electrode configured to be placed in a solution that includes a compound;

a sensor configured to detect an electrical property resulting from the potential; and

a controller configured to determine a concentration of the compound in the solution based at least in part on the electrical property.

62. The device of claim 61 , further comprising a counter electrode.

63. The device of claim 62, wherein the electrical property comprises a current that flows between the working electrode and the counter electrode.

64 The device of claim 61 , further comprising a reference electrode, wherein the potential is relative to the reference electrode.

65. The device of claim 61 , wherein the potential comprises a plurality of potentials applied in increments over a voltage range.

66. The device of claim 65, wherein the voltage range comprises -400 millivolts to 1300 millivolts.

67. The device of claim 61 , wherein the compound comprises hydrogen peroxide.

68. The device of claim 61 , wherein the controller determines the concentration using voltammetry or amperometry.

69. The device of claim 61 , wherein the sensor is configured to determine a salt concentration of water used to form the solution with the compound.

70. The device of claim 69, wherein the controller determines the concentration of the compound based at least in part on the salt concentration of the water used to form the solution.