TWI500929B - Voltage ion sensor read signal correction system - Google Patents

Description

Voltage ion sensor read signal correction system

The invention relates to a method for sensor signal correction, in particular to output signal drift correction for voltage ion sensor measurement.

The Ion Sensitive Field Effect Transistor (ISFET) was first proposed by P. Bergveld in 1970. The structural difference was replaced by a metal-oxide-semiconductor field effect transistor with a sensing film of ISFET (Metal- Oxide-Semiconductor Field Effect Transistor (MOSFET) metal gate, which has miniaturization, high input impedance and fast response; Agner Fog proposed a metal oxide pH electrode in 1984 to replace the traditional glass electrode The inconvenience is fast, easy to carry and easy to store. In recent years, due to the rapid increase in the elderly population ratio in developing countries, the concept of chronic disease management and prevention has emerged, making the biosensors for home testing gradually applied to practical clinical trials.

However, when a circuit component is used as a sensor, a phenomenon of Time-Drift effect is often encountered. Time-Drift refers to a long-term continuous measurement at the same temperature. The output potential of the measurement system drifts with time (Drift), making the sensor less stable, thus limiting the applicability of the sensor. In order to solve this problem, a correction system is needed to assist the correction of the signal.

In addition, the temperature effect (Temperature Effect), that is, the different measurement of the ambient temperature, causes the output signal to shift, which is also a non-ideal effect that the biomedical sensor needs to eliminate.

The invention provides a method and device for correcting non-ideal effects of a sensor. The non-ideal effect correction method and device of the sensor are used to correct signal amplification, temperature effect compensation and time drift effect to eliminate the phenomenon that the output signal drifts due to the measurement environment and time.

The invention provides a voltage ion sensor read signal correction system for measuring a solution to be tested. The voltage ion sensor read signal correction system includes a reference electrode, a sensing component, an amplifier, a temperature test bar, a reading device, and a display device. The reference electrode is used to provide a reference potential. The sensing component is configured to detect the solution to be tested, and generate a sensing signal according to the solution to be tested and the reference potential. The amplifier is configured to receive the sensing signal and amplify the sensing signal to generate a read signal. The temperature test rod is used to measure the temperature of the solution to be tested and generate a temperature signal. The reading device is configured to perform analog-to-digital conversion on the read signal and the temperature signal respectively to generate a corresponding one of the read digital signal and a temperature digital signal. The display device is configured to receive the read digital signal and the temperature digital signal, and display a result according to the read digital signal and the temperature digital signal.

10‧‧‧Voltage type ion sensor read signal correction system

11‧‧‧Sensor components

12‧‧‧Temperature test stick

13‧‧‧Test solution

14‧‧ ‧Amplifier

15‧‧‧Reading device

16‧‧‧ display device

112‧‧‧ reference electrode

31‧‧‧Substrate

32‧‧‧Sensing electrode

33‧‧‧ openings

34‧‧‧Conductor layer

35‧‧‧Insulation

53‧‧‧ hour drift correction system

54‧‧‧Temperature compensation system

55‧‧‧Timer

56‧‧‧Display module

S1‧‧‧Sensor signal

A1‧‧‧ read signal

A2‧‧‧Read digital signal

C1‧‧‧temperature signal

C2‧‧‧Temperature digital signal

VB‧‧‧reference voltage source

GND‧‧‧ Grounding

Digital signal after P1‧‧‧ hour drift correction

P2‧‧‧Measurement signal after temperature compensation

T1‧‧‧ time signal

FIG. 1 is a block diagram of a voltage type ion sensor read signal correction system provided by the present invention.

FIG. 2 is a flow chart of a method for processing a measurement signal of a voltage-type ion sensor read signal correction system provided by the present invention.

Figure 3 is a block diagram of the sensing elements provided by the present invention.

Figure 4 is a block diagram of a display device provided by the present invention.

Figure 5 is a time-lapse graph of the solution to be tested having a pH of 7 after being measured by the apparatus and method provided by the present invention.

Figure 6 is a time-lapse graph of the solution to be tested having a pH of 7 corrected by the apparatus and method provided by the present invention.

Figure 7 is a graph showing the temperature of the solution to be tested after being measured by the apparatus and method provided by the present invention.

Figure 8 is a graph showing the temperature profile of the solution to be tested after being compensated by the apparatus and method provided by the present invention.

The apparatus and method of use of various embodiments of the present invention are discussed in detail below. However, it is worth noting that many of the possible inventive concepts provided by the present invention can be implemented in various specific models. Around. These specific examples are only intended to illustrate the apparatus and methods of use of the present invention, but are not intended to limit the scope of the invention.

FIG. 1 is a block diagram of a voltage type ion sensor read signal correction system provided by the present invention. The voltage ion sensor read signal correction system 10 is used to measure a solution 13 to be tested. It is worth noting that the solution 13 to be tested has an unknown pH value. In one embodiment of the invention, the voltage ion sensor read signal correction system 10 is configured to measure the pH value of the solution 13 to be tested. The voltage ion sensor read signal correction system 10 includes a reference electrode 112, a sensing component 11, an amplifier 14, a temperature test bar 12, a reading device 15, and a display device 16.

The reference electrode 112 is coupled to a reference voltage source VB and immersed in the solution 13 to be tested to provide a reference potential. It should be noted that the material of the reference electrode 112 may be silver or silver chloride, and the invention is not limited herein.

The sensing component 11 is immersed in the solution 13 to be tested for detecting the solution 13 to be tested. The sensing component 11 is further configured to generate a sensing signal S1 according to the reference potential provided by the solution 13 to be tested and the reference electrode 112. And the sensing signal S1 is transmitted to the amplifier 14. It should be noted that in this embodiment, the sensing signal S1 is an analog signal.

The amplifier 14 is configured to receive the sensing signal S1 and amplify the sensing signal S1 to generate a read signal A1. In addition, the amplifier 14 is further configured to transmit the read signal A1 to the reading device 15. In another embodiment of the present invention, the amplifier 14 is further configured to amplify and filter the sensing signal S1 to generate the read signal A1, which is not limited herein. It should be noted that the amplifier 14 can be an operational amplifier 14, a differential amplifier 14, an instrumentation amplifier 14, and/or a voltage amplifier 14, and the invention is not limited herein.

The temperature test rod 12 is used to measure the temperature of the solution 13 to be tested and generate a temperature signal C1. In addition, the temperature test rod 12 is further used to transmit the temperature signal C1 to the reading device 15. It should be noted that the temperature test bar 12 can be a dual carrier transistor, a thermocouple, a temperature measuring chip, and/or a temperature sensing circuit, and the invention is not limited herein. It should be noted that in this embodiment, the temperature signal C1 is an analog signal.

The reading device 15 is configured to perform analog-to-digital conversion on the read signal A1 and the temperature signal C1, respectively, to generate a corresponding one of the read digital signal A2 and a temperature digital signal. C2. In addition, the reading device 15 is further configured to transmit the read digital signal A2 and the temperature digital signal C2 to the display device 16. It should be noted that the reading device 15 can be a data capturing device, an analog-to-digital conversion chip, and/or an analog-to-digital conversion circuit. The invention is not limited herein.

The display device 16 is configured to receive the read digital signal A2 and the temperature digital signal C2, and display a result according to the read digital signal A2 and the temperature digital signal C2. It should be noted that the display device 16 can display the above results by a screen, a voice or a light number, and the present invention is not limited thereto. In an embodiment of the present invention, the display device 16 is further configured to correct the read digital signal A2 according to the temperature digital signal C2 to generate the above result, which is not limited herein.

FIG. 2 is a flow chart of a method for processing a measurement signal of a voltage-type ion sensor read signal correction system provided by the present invention. The measurement signal processing method of the voltage type ion sensor read signal correction system is applied to the voltage type ion sensor read signal correction system 10 shown in FIG. The flow begins in step S200 and/or step S204.

In step S200, one of the first ends of the sensing element 11 is in contact with the solution 13 to be tested to generate a sensing signal S1 according to the reference potential provided by the solution 13 to be tested and the reference electrode 112.

Next, in step S202, one of the second ends of the sensing element 11 is electrically coupled to the amplifier 14 to transmit the generated sensing signal S1 to the amplifier 14. Next, the amplifier 14 amplifies the sensing signal S1 to generate the read signal A1, and transmits the read signal A1 to the reading device 15.

Next, in step S204, the first end of one of the temperature test bars 12 is in contact with the solution 13 to be tested to generate a temperature signal C1. In addition, the second end of one of the temperature test bars 12 is coupled to the reading device 15 and transmits the generated temperature signal C1 to the reading device 15. It is to be noted that, in order to clearly explain the method provided by the present invention, the second diagram divides the flow into steps S200-S204 to describe the actions of the respective components, but the present invention does not limit the sequential execution sequence of steps S200 and S204. . In an embodiment of the present invention, step S200 and step S204 can be performed simultaneously. In another embodiment of the present invention, step S204 may be performed before step S200, and the present invention is not limited thereto.

Next, in step S206, the reading device 15 performs analog-digital conversion on the read signal A1 and the temperature signal C1, respectively, to generate the read digital signal A2 and the temperature digital signal. No. C2.

Next, in step S208, the display device 16 corrects the read digital signal A2 and the temperature digital signal C2 captured from the reading device 15, and displays the corrected result on a screen (not shown).

Figure 3 is a block diagram of the sensing elements provided by the present invention. In the present embodiment, the sensing element 11 includes a substrate 31, a sensing electrode 32, a conductor layer 34, and an insulating layer 35, but the invention is not limited thereto. For example, the substrate 31 may be a plastic substrate 31 or a germanium substrate 31, but the invention is not limited thereto. The sensing electrode 32 is formed over the substrate 31. The conductor layer 34 is formed on the substrate 31 and electrically connected to the sensing electrode 32 for transmitting the sensing signal S1 to the amplifier 14 . It should be noted that the conductor layer 34 may be silver glue or carbon glue, and the invention is not limited herein. The insulating layer 35 is formed over the sensing electrode 32 and the conductor layer 34, wherein the insulating layer 35 has an opening 33 such that the sensing electrode 32 can be in contact with the solution 13 to be tested.

In a preferred embodiment of the present invention, the substrate 31 is a flexible plastic substrate, wherein the sensing electrode 32 in the substrate 31 is deposited by a radio frequency sputtering system with a square area of 4 mm 2 of cerium oxide (RuO 2 ). )film. Further, silver paste is formed on the substrate 31 by screen printing, and baked at a temperature of 110 to 140 degrees Celsius for 20 to 40 minutes to harden the silver paste to form the conductor layer 34. The first end of the conductor layer 34 is in electrical contact with the sensing electrode 32, and the second end of the conductor layer 34 is coupled to the input end of the amplifier 14. Finally, the epoxy resin is formed on the sensing electrode 32 and the conductor layer 34 by screen printing, and baked at 120 to 140 degrees Celsius to fix the epoxy resin to form the insulating layer 35. The insulating layer 35 has a circular opening 33 having a diameter of 2 mm to expose the sensing electrode 32.

Figure 4 is a block diagram of a display device provided by the present invention. In the present embodiment, the display device 16 includes a time drift correction system 53, a temperature compensation system 54, a timing device 55, and a display module 56.

The time drift correction system 53 is configured to receive the read digital signal A2 from the reading device 15 and receive a time signal T1 from the timing device 55, and perform a time drift on the read digital signal A2 according to a first function and a time signal T1. Correction to generate a digital signal P1 after one-time drift correction. For example, the first function is shown in equation (1): P1=A2-(T1-18000)×W.........Formula (1)

The drift amount W is the amount of drift of the read digital signal A2 generated by the sensing element 11 during a predetermined period of time after the solution 13 is immersed. In one embodiment of the present invention, the drift amount W may be the amount of drift of the read digital signal A2 generated by the sensing element 11 from the 5th hour to the 12th hour after the solution 13 is immersed. For example, as shown in FIG. 5, the response voltage generated by the sensing element 11 at the 5th hour after the solution 13 is immersed (ie, the voltage represented by the read digital signal A2) is 1428 millivolts, and the sense is The response voltage generated by the measuring element 11 at the 12th hour after the immersion of the solution 13 to be tested (ie, the voltage represented by the read digital signal A2) is 1444 millivolts. Therefore, the value obtained by dividing 1444 millivolts by 1428 millivolts divided by the time difference (12 hours - 5 hours = 7 hours) is the drift amount W. In other embodiments, the drift amount W may be the amount of drift of the read digital signal A2 generated by the sensing element 11 from the 5th hour to the 13th hour after the solution 13 is immersed, and the present invention does not limit.

In addition, the drift amount W may be a value previously stored in the time drift correction system 53 after the measurement. In another embodiment of the present invention, the time drift correction system 53 can calculate the drift amount W according to the measured digital signal A2 when measuring the pH value of the solution 13 to be tested, and calculate After the drift amount W, the drift amount W is substituted into the formula (1), and the read digital signal A2 is corrected. For example, the time drift correction system 53 can calculate the drift amount W according to the measured digital signal A2 measured at the 5th hour and the 12th hour when measuring the pH value of the solution 13 to be tested, and calculate After the drift amount W (i.e., after the 12th hour), the drift amount W is substituted into the formula (1), and the read digital signal A2 is corrected, but the present invention is not limited thereto.

The temperature compensation system 54 is configured to receive the temperature digital signal C2 and the digital signal P1 after the time drift correction, and perform temperature correction on the time-lapsed digital signal P1 according to a second function and the temperature digital signal C2 to generate A temperature compensated measurement signal P2. For example, the second function is shown in equation (2):

The ion sensitivity S is the amount of change in the response voltage generated by the sensing element 11 in the solution 13 of different pH values (ie, the voltage represented by the read digital signal A2). It is worth noting that the ion sensitivity S is a value previously stored in the temperature compensation system 54 after being measured. For example, the device designer can previously immerse the sensing element 11 in the solution 13 of different pH values, and measure the response voltage generated by the sensing element 11, respectively. Next, a graph of the response voltage versus the pH value is plotted based on the measured result, and the slope of the curve in the graph is the ion sensitivity S.

The temperature sensitivity ST1 is the amount of change in the ion sensitivity S of the response voltage (ie, the voltage represented by the read digital signal A2) generated by the sensing element 11 in the solution 13 to be tested at different temperatures. It is worth noting that the temperature sensitivity ST1 is a value previously stored in the temperature compensation system 54 after being measured. For example, the device designer can pre-measure the ion sensitivity S at different temperatures. Next, a graph of the ion sensitivity S versus temperature is plotted based on the measured result, and the slope of the curve in the graph is the temperature sensitivity ST1.

The timing device 55 is configured to calculate the elapsed time of the solution 13 to be tested, and generate a time signal T1.

The display module 56 is configured to display the result corresponding to the temperature-compensated measurement signal P2. It should be noted that the display module 56 can be disposed in the display device 16 or outside the display device 16. The invention is not limited herein. For example, the display module 56 can be disposed in a notebook computer, a palmtop computer, a mobile phone, or a liquid crystal screen. The invention is not limited herein.

Figure 5 is a time-lapse graph of the solution to be tested having a pH of 7 after being measured by the apparatus and method provided by the present invention. Figure 6 is a time-lapse graph of the solution to be tested having a pH of 7 corrected by the apparatus and method provided by the present invention. As can be seen from Fig. 5 and Fig. 6, the time drift before the correction was 2.29 mV/hr, and the time-lapse after the correction was 0.05 mV/hr. Therefore, the time-lapse rate of the digital signal P1 after the time-lapse correction corrected by the apparatus and method provided by the present invention is reduced by 2.24 mV/hr.

Figure 7 is a graph showing the temperature of the solution to be tested after being measured by the apparatus and method provided by the present invention, wherein the seventh graph measures the pH values of 1, 3, 5, 7, 9, 11 at different ambient temperatures. , 13 the temperature profile of the solution 13 to be tested. Figure 8 is a temperature graph of the solution to be tested after being compensated by the apparatus and method provided by the present invention, wherein the figure 8 is at different ambient temperatures The temperature profile of the solution 13 to be tested having a pH of 1, 3, 5, 7, 9, 11, and 13 was measured. It can be seen from Fig. 7 and Fig. 8 that the temperature coefficient before calibration is 0.047 pH/Celsius per degree (pH/oC), and the temperature coefficient after compensation is 0.018 pH/Celsius per degree (pH/oC). The temperature coefficient is the rate of change of the pH value per degree Celsius. In other words, the larger the temperature coefficient, the larger the error value of the measurement result due to the temperature, and the smaller the temperature coefficient, the smaller the error value of the measurement result due to the temperature. Therefore, the temperature coefficient of the temperature-compensated measurement signal P2 after the temperature is compensated by the apparatus and method provided by the present invention is reduced by 0.029 pH/Cels per degree (pH/oC).

The method of the invention, or a particular type or portion thereof, may exist in the form of a code. The code can be stored in a physical medium such as a floppy disk, a CD, a hard disk, or any other machine readable (such as computer readable) storage medium, or is not limited to an external form of computer program product, wherein When the code is loaded and executed by a machine, such as a computer, the machine becomes a device for participating in the present invention. The code can also be transmitted over a number of transmission media, such as wires, cables, fiber optics, and/or any transmission type, where the machine becomes part of the program when it is received, loaded, and executed by a machine, such as a computer. Invented device. When implemented in a general purpose processing unit, the code combination processing unit provides a unique means of operation similar to application specific logic.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any of the objects, advantages, and/or features of the present invention are not required to be construed as the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

10‧‧‧Voltage type ion sensor read signal correction system

11‧‧‧Sensor components

12‧‧‧Temperature test stick

13‧‧‧Test solution

14‧‧ ‧Amplifier

15‧‧‧Reading device

16‧‧‧ display device

112‧‧‧ reference electrode

S1‧‧‧Sensor signal

A1‧‧‧ read signal

A2‧‧‧Read digital signal

C1‧‧‧temperature signal

C2‧‧‧Temperature digital signal

VB‧‧‧reference voltage source

GND‧‧‧ Grounding

Claims (10)

A voltage-type ion sensor read signal correction system for measuring a solution to be tested, comprising: a reference electrode for providing a reference potential; and a sensing component for detecting the solution to be tested, and Generating a sensing signal according to the solution to be tested and the reference potential; an amplifier for receiving the sensing signal, and amplifying the sensing signal to generate a read signal; and a temperature test rod for measuring The temperature of the solution to be tested generates a temperature signal; a reading device is configured to respectively perform analog-to-digital conversion on the read signal and the temperature signal to generate a corresponding one of the digital signal and a temperature digital signal And a display device for receiving the read digital signal and the temperature digital signal, and displaying a result according to the read digital signal and the temperature digital signal. The voltage type ion sensor read signal correction system according to claim 1, wherein the material of the reference electrode is silver or silver chloride. The voltage ion sensor read signal correction system according to claim 1, wherein the temperature test rod is a double carrier transistor, a thermocouple, a temperature measurement chip or a temperature sensing. Circuit. The voltage-type ion sensor read signal correction system according to claim 1, wherein the amplifier is an operational amplifier, a differential amplifier, an instrumentation amplifier or a voltage amplifier. The voltage-type ion sensor read signal correction system according to claim 1, wherein the reading device is a data acquisition device, an analog-to-digital conversion chip or an analog-to-digital conversion circuit. The voltage ion sensor read signal correction system according to claim 1 of the patent application scope, The sensing component further includes: a substrate; a sensing electrode formed on the substrate; a conductor layer formed on the substrate and electrically connected to the sensing electrode for transmitting the sensing signal to the above And an insulating layer formed on the sensing electrode and the conductor layer, wherein the insulating layer has an opening, so that the sensing electrode can be in contact with the solution to be tested. The voltage-type ion sensor read signal correction system according to claim 6, wherein the substrate is a plastic substrate or a germanium substrate. The voltage-type ion sensor read signal correction system according to claim 6, wherein the conductive layer is silver glue or carbon glue. The voltage-type ion sensor read signal correction system of claim 1, wherein the display device further comprises: a timing device for calculating a time for measuring the solution to be tested, and generating a time signal a one-time drift correction system for receiving the read digital signal and the time signal, and performing a time drift correction on the read digital signal according to a first function related to the drift amount and time and the time signal Generating a digital signal after the drift correction; a temperature compensation system for receiving the temperature digital signal and the digital signal after the time drift correction, and according to a second function related to ion sensitivity, temperature sensitivity, and temperature, and the foregoing a temperature digital signal, wherein the temperature-corrected digital signal is subjected to a temperature correction to generate a temperature-compensated measurement signal; and a display module for displaying the above-mentioned temperature-compensated measurement signal result. The voltage ion sensor read signal correction system according to claim 9, wherein the display module can be disposed on a notebook computer, a palmtop computer, a mobile phone or One in the LCD screen.