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WO1987006342A1 - Dispositif de mesure de fluides biologiques - Google Patents

Dispositif de mesure de fluides biologiques Download PDF

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Publication number
WO1987006342A1
WO1987006342A1 PCT/US1987/000822 US8700822W WO8706342A1 WO 1987006342 A1 WO1987006342 A1 WO 1987006342A1 US 8700822 W US8700822 W US 8700822W WO 8706342 A1 WO8706342 A1 WO 8706342A1
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WO
WIPO (PCT)
Prior art keywords
membrane
electrode
layer
biological fluid
measuring device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1987/000822
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English (en)
Inventor
Mark C. Shults
Christopher C. Capelli
Stuart J. Updike
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Markwell Medical Institute Inc
MARKWELL MEDICAL INST Inc
Original Assignee
Markwell Medical Institute Inc
MARKWELL MEDICAL INST Inc
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Filing date
Publication date
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Publication of WO1987006342A1 publication Critical patent/WO1987006342A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/28—Electrolytic cell components
    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
    • G01N27/327—Biochemical electrodes, e.g. electrical or mechanical details for in vitro measurements
    • G01N27/3271—Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
    • A61B5/1468—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
    • A61B5/1486—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means using enzyme electrodes, e.g. with immobilised oxidase

Definitions

  • the present invention relates to devices having replaceable membranes which cooperate with an electrode assembly to determine the amount of a substance in a biological fluid.
  • Electrode systems have been developed for this purpose whereby an enzyme-catalyzed reaction is monitored by an electrochemical sensor.
  • the electrochemical sensor comprises an electrode with potentiometric or amperometric function in close contact with a thin layer containing an enzyme' in dissolved or insoluble form.
  • the thin layer may also include a co-enzyme.
  • a semipermeable membrane separates the thin layer of the electrode containing the enzyme from the sample of biological fluid that includes the substance to be measured.
  • the electrochemical sensor measures the concentration of the substance involved in the enzyme reaction. For example, the concentration of a co-enzyme or a reaction product can be determined. This concentration may be related to the substrate concentration in the sample by its stoichiometric relationship and by calibration of the electrode system.
  • enzyme electrodes have been developed, and the operation of those electrodes varies depending on the nature of the enzyme reaction and the particular substance being measured.
  • enzyme electrodes include those that measure: (1) a reactant or product of the enzyme reaction; (2) the consumption of a co-enzyme based on the decrease of its initial concentration and (3) the amount of the reduced or oxidized form of a co-enzyme produced during the enzyme reaction.
  • the operation of a particular enzyme electrode depends on a number of parameters including diffusion processes, kinetics of the enzyme reaction and the type of electrochemical sensor.
  • the operation of the electrode can be affected by the diffusion of substances through the semipe eable membrane.
  • Electrode systems that include enzymes have been used to convert amperometrically inactive substances into reaction products which are amperometrically active.
  • glucose which is relatively inactive amperometrically
  • glucose oxidase may be catalytically converted by the enzyme glucose oxidase in the presence of oxygen and water to gluconic acid and hydrogen peroxide.
  • Hydrogen peroxide is anodically active and produces a current which is proportional to the concentration of hydrogen peroxide in the blood sample and thus to the concentration of glucose in the sample.
  • the purpose of the membrane over the enzyme in a glucose sensing electrode system is to limit the amount of glucose that passes or diffuses through the membrane. This extends the upper limit of linearity of glucose measurement from a low value without the
  • a semipermeable membrane can comprise a porous structure consisting of a relatively impermeable matrix that includes a plurality of "microholes" or pores of molecular dimensions. Transfer through these membranes is primarily due to passage of substances through the pores. In other words, the membrane acts as a microporous barrier or sieve.
  • Examples of materials that may be used to form such membranes include polyethylene, polyvinyl chloride, tetrafluoroethylene, polypropylene, cellophane, polyacrylamide, cellulose acetate, poly ethyl methacrylate, silicone polymers, polycarbonate, cuprophane and collagen.
  • the upper size limit to diffusion will be determined by the largest pore diameter, and the overall diffusion rate will depend on the total number of pores for movement of the substance. Passage of a substance through a monolithic, homogeneous membrane, on the other hand, depends upon dissolution and diffusion of the substance as a solute through a solid, non-porous film.
  • monolithic means substantially non-porous and having a generally unbroken surface.
  • homogeneous with reference to a membrane, means having substantially uniform characteristics from one side of the membrane to the other.
  • a membrane may have heterogeneous structural domains, for example, created by using block copolymers, and still be characterized functionally as homogeneous with respect to its dependence upon dissolution rather than sieving to effect separation of substances.
  • a monolithic membrane can thus be used to separate components of a solution on the basis of properties other than the size, shape and density of the diffusing substances.
  • the membrane acts as a barrier because of the preferential diffusion therethrough of some substance (a solute) .
  • Such a device should accurately measure the amount of a substance in a sample without dilution or pretreatment of the sample.
  • a basis for selecting appropriate membrane materials .for use in such devices is needed.
  • the device should also be easy to use and provide a means for replacing the membrane as necessary.
  • the present invention relates to a biological fluid measuring device which permits rapid and accurate determination and measurement of the amount of a particular substance in a biological fluid such as blood.
  • the device includes a main housing carrying electronic circuit means and at least one electrode.
  • at least two electrodes are carried by the housing.
  • a cartridge is removably mounted on the housing.
  • the cartridge includes a membrane which is operably associated with the electrodes when the cartridge is mounted on the housing. It is, of course, possible to design a device wherein one electrode is carried by the housing and a second electrode is carried by another component of the device, as by the cartridge. For ease of description, however, the present device will be described as including at least two electrodes carried by the housing.
  • the cartridge also includes means for protecting the membrane from the ambient surroundings when the device is not in use.
  • the housing includes a case having an upper portion and a lower portion which together define a cavity.
  • the electronic circuit is received within the cavity.
  • the electrode is carried by a post which extends upwardly from a base surface defined by the upper portion of the case.
  • the cartridge preferably includes a body portion which is releasably mounted on the upper portion of the case and a cover which is m ⁇ vably mounted as by a hinge on the body portion.
  • the body portion preferably defines a sidewall which together with the membrane defines a well.
  • the well receives the biological fluid such as a droplet of blood. Because of the particular design of the present invention, the well can be particularly small thereby minimizing the amount of biological fluid sample needed for analysis. In the case of blood, this minimizes both the emotional and physical trauma to the patient.
  • the body portion preferably includes a collar which extends about the post such that, when the cartridge is mounted on the case, the membrane is placed in contact with the electrodes and is stretched over the surface of the electrodes. This insures good operative contact between the electrodes
  • the electrodes, the supporting structure for the electrodes such as the post, and the membrane together form an electrode assembly.
  • the membrane is a multilayered structure including layers formed of materials such as polyethylene, polyvinyl chloride, tetrafluoroethylene, polypropylene, cellophane, polyacrylamide, cellulose acetate, polymethyl methacrylate, silicone polymers, polycarbonate, cuprophane, collagen, polyurethanes and block copolymers thereof.
  • the membrane prevents direct contact of the fluid sample with the electrodes, but permits selected substances of the fluid to pass through the membrane for electrochemical reaction with the electrodes.
  • the membrane is a semi-permeable multilayered membrane having at least one layer formed of a nonporous block copolymer having hydrophobic segments and hydrophilic segments that limits the amount of a substance passing therethrough and a second layer including an enzyme that reacts with the substance to form a product.
  • the electrode assembly comprises an electrode, a first (outer) layer of a block copolymer that limits the amount of a hydrophilic substance passing therethrough, a second (intermediate) layer of a block copolymer including an enzyme bound to the first layer and a third (inner) layer of a block copolymer bound to the second layer and covering the surface of the electrode.
  • the third layer is permeable to relatively low molecular weight substances, such as hydrogen peroxide, but restricts the passage of higher molecular weight substances.
  • the preferred polymers which form the above described membrane layers are selected based on permeability and water swelling.
  • An accepted industry test procedure for determining the permeability of a coating or membrane is ASTM E 96 which measures the moisture-vapor transmission rate of a material. (American Society for Testing and Materials, Philadelphia, PA).
  • the moisture-vapor transmission rate (MVTR) of a membrane material is expressed in grams per square meter per 24 hours and is one means of defining the water resistance of a material.
  • the MVTR of a material may be expressed by the equation:
  • the letter “Q” represents the amount of water vapor (in grams) that permeates the film; the letter “a” represents the film area (in square centimeters) and the letter “t” represents the time (in hours at a designated thickness) . This value can be converted to grams of water per square meter per 24 hours.
  • the MVTR values identified herein are for membranes that are about 1 mil thick.
  • the MVTR of the first (outer) layer described herein should be greater than about 4000 grams per square meter per 24 hours, preferably greater than about 5000 grams per square meter per 24 hours.
  • the MVTR of the third (inner) layer of the assembly should be from about 500 to about 4000 grams per square meter per 24 hours, preferably from 1000 to 3500 grams per square meter per 24 hours.
  • the enzyme is glucose oxidase and the substance to be measured is glucose.
  • the amount of glucose for example, in an aliquot of undiluted whole blood, is determined by measuring the amount of hydrogen peroxide produced during the oxidation of glucose to gluconic acid by the enzyme.
  • Preferred polymers may also be selected by studying water uptake or the swelling of the polymer. This is normally measured by soaking the polymer sample in water at a controlled temperature and exposure conditions until equilibrium' is achieved followed by rapid drying of surface water and weighing of the polymer sample. Subtracting the dry weight from the swelled weight and then dividing by the dry weight and multiplying the value obtained by 100 provides the swell rate as a percent of dry weight.
  • the swell rate of the first (outer) layer described herein should be greater than about 5 percent and preferably greater than about 10 percent.
  • the swell rate of the third (inner) layer should be less than about 5 percent preferably less than about 3 percent.
  • the present invention is not limited to the measurement of glucose concentrations, and other enzyme-substrate systems can be used.
  • enzymes include galactose oxidase, uricase, cholesterol oxidase, alcohol oxidase, lactose oxidase, L-amino acid oxidase, D-amino acid oxidase, xanthine oxidase and ascorbic acid oxidase. Nonetheless, to demonstrate the improvement of this invention over other membrane systems, the invention will be described in terms of measuring glucose concentrations based on the production of hydrogen peroxide by the action of glucose oxidase.
  • the membrane systems currently available are based on semipermeable membranes with microholes or pores. With these membranes there is little selectivity in the separation of substances that are rather close in size, except when the molecular diameters of the substances approach the diameters of the pores. When this occurs, forces between the substance and the surface of the pore channel may influence the rate of transfer.
  • the layers of the preferred multilayered membrane described herein each comprise homogeneous, monolithic membranes and differ in composition, structure and operation from conventional microporous membranes. This represents a substantial improvement over current membrane systems in terms of ease of manufacturing, lifetime of enzyme activity, and the ability to measure the concentrations of substances in undiluted samples.
  • passage of substances through the membranes described herein depends upon dissolution and diffusion of the substance through a solid, non-porous film.
  • Components of a solution can be separated on the basis of properties other than the size, shape and density of the diffusing substance.
  • Figure 1 is a perspective view of biological fluid measuring device of the present invention showing a cartridge received on a housing;
  • Figure 2 is an exploded perspective view of the device of Figure 1 showing the cartridge above and separated from the housing;
  • Figure 3 is a top plan view of the device of Figure 1 showing the cover of the cartridge open and the membrane exposed;
  • Figure 4 is a side elevational view taken in section along the plane 4-4 of Figure 1;
  • Figure 4a is an enlarged view of the portion of Figure 4 that is outlined in phantom;
  • Figure 5 is a top plan view of a second embodiment of the electrode assembly
  • Figure 6 is a side elevational view showing a device including the electrode assembly of Figure 5 taken in section along a plane similar to that shown as plane 4-4 of Figure 1;
  • FIG. 7 is an electronic circuit diagram in block form. Detailed Description of the Invention
  • the present invention relates to a biological fluid measuring device which permits rapid and accurate measurement of the amount of a particular substance in a biological fluid.
  • One particular use of the present invention is to determine the level of glucose in blood using only a small sample. This is a particularly important measurement for individuals having diabetes, and the device is a substantial development over devices that are now being used by individuals with diabetes to determine glucose levels.
  • the measuring device comprises a main housing 12 and a cartridge 14 which is removably mounted on the housing (see Figure , 2).
  • the housing 12 includes a case 16 having an upper portion 18 and a lower portion 22.
  • the upper portion 18 and lower portion 22 are connected together by any particular fastening means such as several screws which are not shown.
  • the main housing 12 also includes electronic circuit means which can be carried in part on a circuit board 24.
  • the electronic circuit means is preferably maintained in a cavity 26 which is defined by the case 16.
  • the housing also includes at least one electrode. In the embodiment shown in Figure 4, three electrodes 28, 30 and 32 are shown.
  • the cartridge 14 includes a membrane 34 which is operably associated with the electrodes 28, 30, and 32 when the cartridge is removably mounted on the housing 12.
  • the cartridge 14 also includes means for protecting the membrane when not in use.
  • the protection means is preferably a cover 36 which is movably mounted on a body portion 38 of the cartridge 14.
  • the cover 36 may be mounted on the case 16.
  • the cover 36 is movably mounted on the body portion 38 by a hinge assembly 40.
  • the cover 36 has a first position such as shown in Figures 1 and 4 in which it protects the membrane 34 and a second position such as shown in Figure 3 which permits access to the membrane. Access to the membrane 34 is necessary to place the biological fluid sample on the membrane for analysis.
  • the body portion preferably defines an opening having a sidewall 42 which together with a portion of the membrane 34 defines a well 44 having a bottom 45.
  • the bottom 45 of the well is defined at least in part by the membrane 34.
  • the biological fluid sample is placed in the well 44 for analysis.
  • the sidewall 42 defines an opening of less than 4 millimeters in diameter and the well 44 has the depth of less than 2 millimeters.
  • the well has a volume of less than about 0.1 to 0.2 cubic centimeters. This substantially minimizes the size of the biological fluid sample necessary for analysis down to the sample sizes a small as about five microliters. Because the size of the sample can be particularly small, compensation for temperature changes during analysis which was often necessary with previous devices can be avoided.
  • the protection means of the cartridge 14 preferably also includes means for sealing the well 44 and hence the operative portion of the membrane 34 at the bottom 45 of the well 44 from the ambient surroundings.
  • This can include a flexible gasket 46 which extends about the well 44 and cooperates with the body portion 38 and cover 36.
  • the gasket 46 is preferably mounted in a groove 48 defined by the body portion 38 and is engaged by a ring 50 carried on the cover 36.
  • the ring 50 engages the gasket 46 to seal the well 44 and membrane 34 from the ambient surroundings and to prevent dehydration of the membrane. This also prevents damage to the membrane by physical intrusion or dirt.
  • the ring 50 is preferably provided with a edged surface which bites into the gasket to provide a particularly effective seal.
  • a retaining means is also provided for releasably retaining the cartridge 14 and its body portion 38 on the housing 12.
  • the retaining means preferably includes a detent 52 on the cartridge 14 which is received in a recess 53 defined by the upper portion 18 of the case 16.
  • the retaining means also preferably includes at least one, and optimally, two wings 54 on the body portion 38 of the cartridge 14 which are received in one or more slots 56 on the case 16. (See, in particular. Figure 2).
  • the slots 56 are generally perpendicular to the cover 36 so that opening the cover will not disengage the wings 54 from the slots 56.
  • the upper portion 18 of the case 16 preferably defines a recessed cell 57 (see Figure 2) into which the cartridge 14 is received.
  • the bottom portion of the cell 57 is defined by a base surface 58.
  • the electrodes 28, 30 and 32 preferably extend upwardly from the base surface 58.
  • the electrodes are preferably mounted within a post 60 which supports the electrodes as they extend upwardly of the base surface 58.
  • the post is preferably generally annular in design with the interior portion thereof filled with an electrically nonconductive support material 62 such as a hardened polyepoxide-containing resin.
  • the electrically nonconductive support material 62 and the top portions of the electrodes define a membrane contact surface 64.
  • the membrane contact surface 64 is preferably generally dome-shaped, such that the membrane 34 can be stretched over the contact surface to more effectively place the membrane in operative association with the electrodes.
  • the body portion 38 preferably also includes a collar 66 which extends opposite of the well 44 with respect to the membrane 34 where it defines the bottom 45 of the well. As shown in Figure 4, the collar 66 extends about the post 60.
  • the membrane 34 is preferably attached to a retaining surface 65 by an adhesive at the edge of the collar 66 with the portion of the membrane within the collar being free to move. As the cartridge 14 is mounted on the housing 12, the membrane is then stretched over the post 60 providing continuous contact between membrane 34 and the contact surface 64.
  • the cover 36 is preferably provided with a closure means 72 such as one or more latches which engage the body portion 38. Generally, the force necessary to disengage the closure means 72 from the body portion 38 should be less than that necessary to disengage the wings 54 from the slots 56.
  • the electrodes 28, 30 and 32 together with support assembly such as post 60 and the membrane 34 comprise the electrode assembly. It is this assembly which is contacted with the body fluid sample for analysis.
  • the electrode assembly 74 is operably associated with the electronic circuit means which analyzes the current from the reaction of the components in the body fluid with the electrodes.
  • the electronic circuit means is in turn operably associated with display means such as a liquid crystal display 76 to indicate amount of glucose in the fluid sample.
  • FIG. 5 another embodiment of the electrode assembly 74 is shown wherein the three electrodes 28, 30 and 32 are deposited onto a ceramic surface 66.
  • An electrically nonconductive material 62 is applied as a coating over the electrodes to form an insulating barrier. A portion of each electrode, however, is not coated to form a membrane contact surface 64 so that a membrane can be applied over the electrodes in operative contact therewith.
  • Figure 6 shows the electrode assembly 74 of Figure 5 in the device.
  • the electrode assembly including the membrane 34 is positioned within a recess 78 in the base surface 58 of the recessed cell 57.
  • the cartridge 14 is then positioned within the recessed cell as described above whereby the bottom 45 of the well 44 in the body portion 38 of the cartridge contacts the membrane 34.
  • a cover 36 (as shown in Figure 4) can be attached to the body portion 38 to protect the membrane when the device is not in use.
  • silver/silver chloride electrodes provide a stable reference system for electrochemical sensors.
  • a silver/silver chloride electrode is typically formed by treating a silver surface with an oxidant and chloride ions (such as by treatment with ferric chloride or a neutral hypochlorite solution) , by electrochemical plating of chloride ions onto a silver surface or by the mechanical forming of silver and silver chloride by sintering or similar processes.
  • CMOS circuitry is used throughout the device and provides a use-dependent battery life of one to two years.
  • a representative electronic circuit for the device is shown in Figure 7, but other circuits may also be employed. See, for example, Implantable Sensors for Closed Loop Prosthetic Systems, edited by Wen H. Ko, ch. 12, pages 167-175, Futura Publishing Co., Mount Kisco, N.Y. (1985), the noted relevant pages of which are incorporated herein by reference.
  • glucose from the blood sample produces a current flow at the working electrode 28.
  • Equal current is provided by a counter electrode 30 in a reference circuit 82.
  • the current is converted in an analog section 84 by a current to voltage converter to a voltage which is inverted, level-shifted and delivered to an Analog/Digital (A/D) converter 86 in the microprocessor 88.
  • A/D Analog/Digital
  • the microprocessor can set the analog gain via its control port 90.
  • the A/D converter is activated at one second intervals.
  • the microprocessor looks at the converter output with any number of pattern recognition algorithms known to those skilled in the art until a glucose peak is identified.
  • a timer is then activated for about 30 seconds at the end of which time the difference between the first and last electrode current values is calculated. This difference is then divided by the value stored in the memory during instrument calibration and is then multiplied by the calibration glucose concentration.
  • the glucose value in milligram percent or millimoles per liter is then displayed on the LCD display screen 94.
  • prompts or messages may be displayed on the LCD screen to guide the user through the calibration and sample measurement procedures.
  • prompts may be displayed to inform the user about necessary maintenance procedures, such as "Replace Sensor" or
  • An on/off button 80 initiates the operation and calibration sequences.
  • the membrane is a multilayered structure including layers formed of materials such as polyethylene, polyvinyl chloride, tetrafluoroethylene, polypropylene, cellophane, polyacrylamide, cellulose acetate, polymethyl methacrylate, silicone polymers, polycarbonate, cuprophane, collagen, polyurethanes and block copolymers thereof.
  • the membrane is a semi-permeable multilayerd membrane having at least one layer formed of a nonporous block copolymer having hydrophobic segments (such as silicone polymer segments, aromatic and aliphatic polymer segments, polypropylene oxide segments, polytetra-methylene oxide segments and the like) and hydrophilic segments (such as polyoxyethylene segments, polyvinylpyrrolidone segments, polyvinyl alcohol segments and the like) that limits the amount of a substance passing therethrough and a second layer including an enzyme that reacts with the substance to form a product.
  • hydrophobic segments such as silicone polymer segments, aromatic and aliphatic polymer segments, polypropylene oxide segments, polytetra-methylene oxide segments and the like
  • hydrophilic segments such as polyoxyethylene segments, polyvinylpyrrolidone segments, polyvinyl alcohol segments and the like
  • the first layer limits the amount of a substance in a fluid that can pass therethrough.
  • the substance can react with the enzyme in the second layer to produce one or more reaction products.
  • a third layer that is permeable to one of the reaction products, but which restricts the passage ' of other materials may also be used.
  • the ability of each layer to limit the amount of a molecule that can pass therethrough may be expressed in terms of the moisture-vapor transmission rate (MVTR) and water swelling of the material that forms the layer.
  • MVTR moisture-vapor transmission rate
  • water swelling of the material that forms the layer As used herein, the MVTR of a material is measured as described in ASTM E 96, the procedure of which is incorporated herein by reference.
  • the MVTR of the block copolymer of the first layer should be greater than about 4000 grams per square meter per 24 hours, preferably greater than about 5000 grams per square meter per 24 hours.
  • the water swelling of this layer should be greater than about 5 percent.
  • the MVTR of the block copolymer of the third layer should be from about 500 to about 4000 grams per square meter per 24 hours.
  • the above values relate specifically to layers that are employed to measure the amount of glucose in a biological sample. It will be understood that block copolymers having different MVTR values can be used to measure the amounts of other substances in biological sample and the description of glucose measurement is only illustrative.
  • the most preferred membranes of this invention are formed of polyurethanes which, of course, include u ethane groups and polyurethaneureas which also include urea groups.
  • the polyurethanes and the polyurethaneureas of the present membrane system are based on poly(oxyalkylene) glycols including poly(oxyethylene) glycol. In accordance with conventional usage, both types of polymers will be referred to herein as polyurethanes.
  • Membranes of polyurethanes based on poly(oxyalkylene) glycol display no predictable relationship between molecular weight and permeability. The unique separation observed with the present membranes may be explained on the basis of substance-membrane or solute-membrane interactions which tend to affect the partitioning of the substance into the membrane. This partitioning is not due only to the hydrophilic poly(oxyalkylene) glycol or "soft" segment, but the hydrophobic or "hard” segment of the block copolymer also contributes to the overall selectivity.
  • the selectivity of the membrane system can be modified.
  • the membrane system of this invention for example, the use of two different membranes of block copolyether urethanes based on poly(oxyalkylene) glycol produces the desired selectivity for glucose and hydrogen peroxide.
  • the preferred poly(oxyalkylene) glycols of this invention include poly(oxyethylene) glycols, poly(oxytetramethylene) glycols and poly(oxypropylene) glycols.
  • the organic diisocyanates suitable for use in the preparation of the polyurethanes of the present membranes include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and 4,4'-diphenylmethane diisocyanate.
  • the use of 4,4'-diphenylmethane diisocyanate is preferred.
  • Diols useful herein include ethylene glycol, propylene glycol, 1,5-dihydroxypentane, 1,6-dihydroxyhexane, 1,10-dihydroxydecane, 1,4-cyclohexane diol, 1,3-dihydroxyneopentane and alpha, alpha 1 -dihydroxy-p-xylene.
  • Diamines useful in the preparation of the polyurethanes described herein include ethylene- diamine, 1,2- (and 1,3-) propanediamine, and methylene-bis-o-chloroaniline.
  • Example 1 ethylene- diamine, 1,2- (and 1,3-) propanediamine, and methylene-bis-o-chloroaniline.
  • the polyurethanes are preferably prepared as block copolymers by solution polymerization techniques as generally described in Lyman, D.J., J. Polymer Sci. , 45, 49 (1960) .
  • a two-step solution polymerization technique is used in which the poly(oxyethylene) glycol is first "capped” by reaction with a diisocyanate to form a macrodiisocyanate. Then the macrodiisocyanate is coupled with a diol (or diamine) and the diisocyanate to form a block copolyetherurethane (or a block copolyurethaneurea) .
  • the resulting block copolymers are tough and elastic and may be solution-cast in N,N-dimethylformamide to yield clear films that demonstrate good wet strength when swollen in water.
  • a membrane formed of a homogeneous, nonporous block copolymer may be prepared as follows. Polymerization is carried out in a 2-liter glass flask with a detachable top containing five inlets. The inlets provide for nitrogen passage, condenser attachment, stirring, thermometer placing, and ingredient addition. A regulated flow of oxygen-free nitrogen passes from a cylinder, through the apparatus, into a water trap, and to the drain. > The contents of the reaction flask are stirred by a Teflon blade connected to an electric motor running at 350 rpm. Air is excluded by a mercury seal. Heat is supplied by an electric mantle and temperature recorded by placing a thermometer in the flask contents. A dropping funnel is used for the addition of ingredients during the reaction.
  • the polymer is dissolved in DMF to provide a 10 percent solution by weight.
  • the solution is filtered under vacuum through a Porosity Gl sintered glass funnel and is stored in a desiccator over phosphorus pentoxide for at least 16 hours.
  • the polymer solution is poured on to a glass plate and is spread as a film by passing a doctor blade across the plate. Solvent evaporation is achieved by maintaining a temperature of 45-50 degrees C for 8 hours in the region of the plate, while solvent vapor is removed by an extractor fan.
  • the membrane is removed from the glass plate by stripping dry or after being soaked with water.
  • the membrane layer nearest the anode comprises a block copolymer, as described above, which is permeable to hydrogen peroxide but which restricts the passage of higher molecular weight substances.
  • This layer has a preferred thickness of less than about 5 microns, more preferably in the range of about 0.1 to about 5 microns and most preferably in the range of about 0.5 to about 3 microns.
  • the membrane layer nearest the sample functions as a diffusion barrier to prevent the passage of high molecular weight substances.
  • This layer also formed of a block copolymer, when used in an electrode assembly to monitor glucose concentrations in a fluid sample, limits the amount of glucose that passes therethrough.
  • This layer has a preferred thickness of less than about 45 microns, more preferably in the range of about 15 to about 40 microns and most preferably in the range of about 20 to about 35 microns.
  • the second (intermediate) layer that binds the inner and outer layers together includes glucose oxidase, galactose oxidase, uricase or the like combined with a block copolymer of this invention.
  • the second layer is applied as a thin uniform layer on either the inner or outer membrane layer and the other membrane layer is brought into contact with the second layer to form a raultilayered membrane (also referred to as a laminate) .
  • the laminate is then dried to cure the enzyme-containing second layer and to bind the layers together.
  • an appropriate carrier or frame made of cardboard, rubber or plastic can be secured to the surface of the laminate or multilayered membrane.
  • the frame includes an opening, for example, in the central portion thereof whereby the outer layer of the membrane may be exposed to the electrode.
  • the electrode assembly of this invention may also be used in the manner commonly employed in the making of amperometric measurements.
  • a sample of the fluid being analyzed is placed in contact with a reference electrode, e.g., silver/silver-chloride, and the electrode of this invention which is preferably formed of platinum.
  • the electrodes are connected to a galvanometer or polarographic instrument and the current is read or recorded upon application of the desired voltage between the electrodes.
  • the ability of the present device assembly to accurately measure the concentration of substances such as glucose over a broad range of concentrations in fluids including undiluted whole blood samples enables the rapid and accurate determination of the concentration of those substances. That information can be employed in the study and control of metabolic disorders including diabetes.

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Abstract

Un dispositif de mesure de fluides biologiques pour déterminer la présence ainsi que les quantités de substances dans un fluide biologique sans qu'il soit nécessaire de diluer le fluide comporte un boîtier principal (12) avec des moyens à circuit électronique (24) et au moins une électrode (28, 30 et 32), ainsi qu'une cartouche (14) munie d'une membrane (34). La cartouche (14) est montée de manière amovible sur le boîtier (12), et la membrane (34) est associée de manière fonctionnelle à l'électrode (28, 30 et 32). La cartouche (14) comporte également des moyens (36) pour protéger la membrane (34) lorsque le dispositif n'est pas utilisé.
PCT/US1987/000822 1986-04-15 1987-04-10 Dispositif de mesure de fluides biologiques Ceased WO1987006342A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US852,343 1977-11-17
US85234386A 1986-04-15 1986-04-15
US85234686A 1986-04-15 1986-04-15
US852,346 1986-04-15

Publications (1)

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WO1987006342A1 true WO1987006342A1 (fr) 1987-10-22

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PCT/US1987/000822 Ceased WO1987006342A1 (fr) 1986-04-15 1987-04-10 Dispositif de mesure de fluides biologiques

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EP (1) EP0267236A4 (fr)
AU (1) AU7354987A (fr)
CA (1) CA1273399A (fr)
WO (1) WO1987006342A1 (fr)

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EP0319873A3 (fr) * 1987-12-09 1990-06-06 Porton Diagnostics, Inc. Méthode et appareil pour une analyse unique du sang
EP0544237A1 (fr) * 1991-11-28 1993-06-02 Petermann, Heike Appareil pour la mesure de la concentration des ions dans des milieux liquides
EP0423225A4 (en) * 1988-07-07 1993-08-04 Markwell Medical Inst.,Inc. Biological fluid measuring device
FR2691248A1 (fr) * 1992-05-12 1993-11-19 Bayer Diagnostics Procédé de surveillance d'une grandeur physique, système convenant à la mise en Óoeuvre de ce procédé, et boîtier compact faisant partie de ce système.
FR2691249A1 (fr) * 1992-05-12 1993-11-19 Bayer Diagnostics Procédé de surveillance d'une grandeur physique, système convenant à la mise en Óoeuvre de ce procédé, et boîtier compact faisant partie de ce système.
JP2013064702A (ja) * 2011-09-20 2013-04-11 Hitachi Maxell Ltd 電極保護体
US9451908B2 (en) 2006-10-04 2016-09-27 Dexcom, Inc. Analyte sensor
US10136844B2 (en) 2006-10-04 2018-11-27 Dexcom, Inc. Dual electrode system for a continuous analyte sensor
US10188333B2 (en) 2003-12-05 2019-01-29 Dexcom, Inc. Calibration techniques for a continuous analyte sensor
US10524703B2 (en) 2004-07-13 2020-01-07 Dexcom, Inc. Transcutaneous analyte sensor
US10610135B2 (en) 2005-03-10 2020-04-07 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10813577B2 (en) 2005-06-21 2020-10-27 Dexcom, Inc. Analyte sensor
US10980461B2 (en) 2008-11-07 2021-04-20 Dexcom, Inc. Advanced analyte sensor calibration and error detection
US11000215B1 (en) 2003-12-05 2021-05-11 Dexcom, Inc. Analyte sensor
US11382539B2 (en) 2006-10-04 2022-07-12 Dexcom, Inc. Analyte sensor
US11633133B2 (en) 2003-12-05 2023-04-25 Dexcom, Inc. Dual electrode system for a continuous analyte sensor

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US4534355A (en) * 1980-10-15 1985-08-13 Smith And Nephew Associated Companies Inc. Electrochemical sensor employing a gas-permeable hydrophilic polyurethane membrane
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Cited By (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0319873A3 (fr) * 1987-12-09 1990-06-06 Porton Diagnostics, Inc. Méthode et appareil pour une analyse unique du sang
EP0423225A4 (en) * 1988-07-07 1993-08-04 Markwell Medical Inst.,Inc. Biological fluid measuring device
EP0544237A1 (fr) * 1991-11-28 1993-06-02 Petermann, Heike Appareil pour la mesure de la concentration des ions dans des milieux liquides
FR2691248A1 (fr) * 1992-05-12 1993-11-19 Bayer Diagnostics Procédé de surveillance d'une grandeur physique, système convenant à la mise en Óoeuvre de ce procédé, et boîtier compact faisant partie de ce système.
FR2691249A1 (fr) * 1992-05-12 1993-11-19 Bayer Diagnostics Procédé de surveillance d'une grandeur physique, système convenant à la mise en Óoeuvre de ce procédé, et boîtier compact faisant partie de ce système.
US11633133B2 (en) 2003-12-05 2023-04-25 Dexcom, Inc. Dual electrode system for a continuous analyte sensor
US11020031B1 (en) 2003-12-05 2021-06-01 Dexcom, Inc. Analyte sensor
US11000215B1 (en) 2003-12-05 2021-05-11 Dexcom, Inc. Analyte sensor
US10188333B2 (en) 2003-12-05 2019-01-29 Dexcom, Inc. Calibration techniques for a continuous analyte sensor
US10299712B2 (en) 2003-12-05 2019-05-28 Dexcom, Inc. Dual electrode system for a continuous analyte sensor
US10980452B2 (en) 2004-07-13 2021-04-20 Dexcom, Inc. Analyte sensor
US10918313B2 (en) 2004-07-13 2021-02-16 Dexcom, Inc. Analyte sensor
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US10813576B2 (en) 2004-07-13 2020-10-27 Dexcom, Inc. Analyte sensor
US10524703B2 (en) 2004-07-13 2020-01-07 Dexcom, Inc. Transcutaneous analyte sensor
US10827956B2 (en) 2004-07-13 2020-11-10 Dexcom, Inc. Analyte sensor
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US11051726B2 (en) 2005-03-10 2021-07-06 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10610135B2 (en) 2005-03-10 2020-04-07 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10898114B2 (en) 2005-03-10 2021-01-26 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10918316B2 (en) 2005-03-10 2021-02-16 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10925524B2 (en) 2005-03-10 2021-02-23 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10856787B2 (en) 2005-03-10 2020-12-08 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10610137B2 (en) 2005-03-10 2020-04-07 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10610136B2 (en) 2005-03-10 2020-04-07 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US11000213B2 (en) 2005-03-10 2021-05-11 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10918318B2 (en) 2005-03-10 2021-02-16 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10918317B2 (en) 2005-03-10 2021-02-16 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10743801B2 (en) 2005-03-10 2020-08-18 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10617336B2 (en) 2005-03-10 2020-04-14 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10709364B2 (en) 2005-03-10 2020-07-14 Dexcom, Inc. System and methods for processing analyte sensor data for sensor calibration
US10813577B2 (en) 2005-06-21 2020-10-27 Dexcom, Inc. Analyte sensor
US9451908B2 (en) 2006-10-04 2016-09-27 Dexcom, Inc. Analyte sensor
US10136844B2 (en) 2006-10-04 2018-11-27 Dexcom, Inc. Dual electrode system for a continuous analyte sensor
US11382539B2 (en) 2006-10-04 2022-07-12 Dexcom, Inc. Analyte sensor
US11399745B2 (en) 2006-10-04 2022-08-02 Dexcom, Inc. Dual electrode system for a continuous analyte sensor
US10980461B2 (en) 2008-11-07 2021-04-20 Dexcom, Inc. Advanced analyte sensor calibration and error detection
JP2013064702A (ja) * 2011-09-20 2013-04-11 Hitachi Maxell Ltd 電極保護体

Also Published As

Publication number Publication date
CA1273399A (fr) 1990-08-28
EP0267236A1 (fr) 1988-05-18
AU7354987A (en) 1987-11-09
EP0267236A4 (en) 1990-10-10

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