Heterogeneous membrane electrodes

• US 10,031,099 B2
• Filed: 06/21/2010
• Issued: 07/24/2018
• Est. Priority Date: 12/02/2002
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Inventors: Lauks, Imants R., Varlan, Anca, Oussova, Alexandra, Bales, Michael
• Primary Examiner(s): Van, Luan V
• Assistant Examiner(s): ROSENWALD, STEVEN ERIC
• Application Number:
  US12/819,273
• Publication Number:
  US 20100252428A1
• Time in Patent Office: 2,955 Days
• Field of Search: 204400, 204295, 204282, 204296, 427 58
• CPC Class Codes: B01L 2200/025 Align devices or objects to ensure defined positions relative to each other
• CPC Class Codes: B01L 2200/148 Specific details about calibrations
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0825 Test strips
• CPC Class Codes: B01L 2300/0883 Serpentine channels
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 2400/0683 mechanically breaking a wall or membrane within a channel or chamber
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: G01N 27/301 Reference electrodes
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 27/31 Half-cells with permeable membranes, e.g. semi-porous or perm-selective membranes

Abstract

The present invention relates to planar electrochemical sensors with membrane coatings used to perform chemical analyses. The object of this invention is to provide unit-use disposable sensors of very simple and inexpensive construction, preferably with only a single membrane coating on an electrode. The invented devices are potentiometric salt-bridge reference electrodes and dissolved gas sensors constructed with a heterogeneous membrane coating of a conductor. The heterogeneous membrane, which is an intimate admixture of a hydrophobic and a hydrophilic compartment, concurrently supports constrained transport of non-volatile species through its hydrophilic compartment and rapid gas and water vapor transport through its hydrophobic compartment.

Claims

1. A dry heterogeneous membrane cast from an oil in water emulsion for an electrochemical sensing electrode for direct exposure to a sample, the membrane comprising

a hydrophobic compartment, the hydrophobic compartment including a gas permeable polymer and having a water vapor diffusion coefficient;

a hydrophilic compartment, the hydrophilic compartment including a hydrophilic polymer and having an aqueous electrolyte diffusion coefficient; and

a dry internal reagent reservoir, wherein the hydrophilic compartment includes the internal reagent reservoir;

wherein the hydrophobic compartment is in excess by volume over the hydrophilic compartment for the water vapor diffusion coefficient of the hydrophobic compartment to be higher than the aqueous electrolyte diffusion coefficient of the hydrophilic compartment and

wherein at least one of the gas permeable polymer and the hydrophilic polymer is at least partially cross-linked, and

wherein the internal reagent reservoir contains at least a bicarbonate salt and a pH sensitive redox couple.

2. An electrode for use in an electrochemical sensing device for the analysis of

an aqueous sample, comprising

an electric conductor;

an insulating layer on the conductor, the insulating layer having a through-going aperture defining an electrode region; and

a heterogeneous membrane as defined in claim 1 for direct contact with the sample, the membrane in physical contact with the insulating layer in the electrode region and in electrical contact with the conductor.

3. The heterogeneous membrane of claim 1, wherein the hydrophobic compartment is in excess by volume over the hydrophilic compartment so that a gas diffusion coefficient of a gas species through the hydrophobic compartment is larger than a aqueous diffusion coefficient of species dissolved in water.

4. The heterogeneous membrane of claim 3, wherein the water vapor diffusion coefficient is at least 10 times larger than the aqueous diffusion coefficient.

5. The heterogeneous membrane of claim 3, wherein the water vapor diffusion coefficient is at least 50 times larger than the aqueous diffusion coefficient.

6. The heterogeneous membrane of claim 1, wherein the water vapor diffusion coefficient is greater than 1×

10<sup>−

6</sup> cm² s<sup>−

1</sup> and the aqueous diffusion coefficient is less than 1×

10<sup>−

7</sup> cm² s<sup>−

1</sup>.

7. The heterogeneous membrane of claim 1, wherein the hydrophobic compartments include a polydimethylsiloxane hydrophobic polymer and the hydrophilic compartment includes a cross-linked polyvinylalcohol containing bicarbonate salt and quinhydrone.

8. An electrochemical sensing device for the analysis of an aqueous sample, comprising

a diagnostic card body, and

an electrode as defined in claim 2 mounted to the card body.

9. The electrochemical sensing device as defined in claim 8, for use as a potentiometric reference electrode, wherein the hydrophilic compartment contains the bicarbonate salt and the pH sensitive redox salt.

10. The electrochemical sensing device as defined in claim 9, wherein the hydrophilic compartment comprises a salt composition which is approximately equi-transferrent.

11. The electrochemical sensing device as defined in claim 8, wherein the hydrophobic compartment contains acrylated siloxane and the hydrophilic compartment contains polyvinylalcohol.

12. The electrochemical sensing device of claim 8, wherein the heterogeneous membrane has an oxygen permeability of less than 6×

10<sup>−

13</sup> mole cm<sup>−

1</sup> s<sup>−

1</sup> atm<sup>−

1</sup>.

13. The electrochemical sensing device of claim 12, wherein the hydrophobic compartment contains epoxy-polyol and the hydrophilic compartment contains polyvinylalcohol.

14. The electrochemical device of claim 9, wherein the one of the hydrophilic compartment and hydrophilic layer further contains carbonic anhydrase.

15. The heterogeneous membrane of claim 1, wherein the hydrophilic compartments constitute less than 5% by volume of the total volume of the heterogeneous membrane.

16. The heterogeneous membrane of claim 1, wherein the hydrophobic compartment comprises a polymer or a derivatized polymer, or a mixture of polymers or derivatized polymers selected from the following group of polymer families:

polysiloxanes, polyurethanes, polyphosphazenes, polybutadienes, polyisoprenes, epoxies, polyvinylacetates and combinations thereof.

17. The heterogeneous membrane of claim 1, wherein the hydrophilic compartment includes a hydrophilic polymer or a mixture of polymers including derivatized polymers selected from the following group of polymer families:

polyvinylalcohols, polyhydroxyacrylates, polyacrylamides, polysaccharides, cellulosic polymers and gelatins and combinations thereof.

18. A method of using the sensing device of claim 8 comprising the steps of;

sequentially exposing the electrode of the sensing device of claim 8 to an aqueous calibrator fluid and a sample fluid.

19. The heterogeneous membrane of claim 1, wherein the water vapor diffusion coefficient is at least 10 times larger than the salt aqueous electrolyte diffusion coefficient.

20. The electrochemical sensing device as defined in claim 11, wherein the acrylated siloxane has a degree of acrylation of no greater than 10%.

21. The electrochemical sensing device as defined in claim 11, wherein the acrylated siloxane has a degree of acrylation of less than 5%.