Electrochemical sensor with solid phase electrolyte

• US 4,925,544 A
• Filed: 02/23/1989
• Issued: 05/15/1990
• Est. Priority Date: 05/15/1987
• Status: Expired due to Fees

• Current Assignee: British Technology Group Ltd. (Boston Scientific Corporation)
• Original Assignee: National Research Development Corporation
• Inventors: Goldring, Lionel S.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): GORGOS, KATHRYN L
• Application Number:
  US07/303,653
• Time in Patent Office: 446 Days
• Field of Search: 204/1 P, 204/414, 204/415, 204/421, 204/422, 204/431, 128/635, 429/30, 429/33, 429/104, 429/192, 324/438, 324/439
• US Class Current: 204/421
• CPC Class Codes: G01N 27/404 Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid , e.g. Clark-type oxygen sensors

Abstract

An electrochemical sensor comprising an electrolyte and an analyte separated by a selectively permeable membrane preferably characterized in that the electrolyte is an electrically conductive solid comprising a homogeneous dispersion of a polymeric matrix phase and an electrically conductive salt and substantially free of water. Preferably the polymeric matrix phase is plasticized, the plasticizer forming a continuous phase in which the conductive salt is dissolved. The sensor is used, for example, for sensing and measuring gases especially in transcutaneous measurement of blood gases.

Claims

1. An electrochemical sensor comprising an electrolyte and an analyte separated by a selectively permeable membrane where the electrolyte comprises an electrically conductive solid comprising a homogeneous dispersion of a polymeric matrix phase, where the polymeric matrix phase is plasticized, and an electrically conductive salt said dispersion being substantially free of water, the plasticizer forming a continuous phase in which the conductive salt is dissolved.

2. A sensor according to claim 1 where the polymetric phase is a polyvinyl alcohol.

3. A sensor according to claim 2 where the polymetric phase is a hydrolyzed polyvinyl acetate having a degree of hydrolysis of from 80 to 99% and a molecular weight of at least 5,000.

4. A sensor according to claim 3 where the plasticizer comprises an aliphatic or cycloaliphatic polyhydric alcohol having from 2 to 9 carbon atoms or a mixture of the least two alcohols having an average of from 2 to 3 hydroxy groups.

5. A sensor according to claim 3 where the plasticizer comprises a mixture of glycerol with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol or 2,2-diethyl-1,3-propanediol.

6. A sensor according to claim 2 where the plasticizer comprises an aliphatic or cycloaliphatic polyhydric alcohol having from 2 to 8 carbon atoms or a mixture of at least two alcohols having an average of from 2 to 3 hydroxy groups.

7. A sensor according to claim 2 where the plasticizer comprises a mixture of glycerol with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol or 2,2-diethyl-1,3-propanediol.

8. A sensor according to claim 1 where the polymetric phase has a solubility parameter of at least 24 megaPascalsq, and a hydrogen bonding parameter γ

_c (Crowley) greater than 18 or δ

_H (Hansen) greater than 17.

9. A sensor according to claim 8 where the plasticizer has about the same solubility parameter and hydrogen bonding parameter as the polymetric phase.

10. A sensor according to claim 9 where the plasticizer has a boiling point of at least 225°

C. at 25°

C. and 1 atmosphere.

11. A sensor according to claim 9 where the boiling point is at least 250°

.

12. A sensor according to claim 8 where the plasticizer has a boiling point of at least 225°

C. at 25°

C. and 1 atmosphere.

13. A sensor according to claim 8 where the boiling point is at least 250°

.

14. A sensor according to any one of claims 1 and 3-11 and 4-11 where the electrolyte has a thickness not greater than 25 micrometers.