Electrochemical sensor with dry ionomer membrane

• US 20030085125A1
• Filed: 10/22/2001
• Published: 05/08/2003
• Est. Priority Date: 10/22/2001
• Status: Active Grant

• Current Assignee: PerkinElmer LAS, Inc. (Perkinelmer Incorporated)
• Original Assignee: PerkinElmer LAS, Inc. (Perkinelmer Incorporated)
• Inventors: Dalmia, Avinash, Prohaska, Otto J.
• Granted Patent: US 7,422,646 B2
• Time in Patent Office: Days
• US Class Current: 204/424
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 27/4071 using sensor elements of laminated structure
• CPC Class Codes: G01N 27/4074 for detection of gases other than oxygen
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A miniaturized gas sensor comprised of film type electrodes, on a non-conductive supportive substrate, and in contact with a dry ionomer electrolyte, for detection of toxic gases, i.e., carbon monoxide, and other oxidizable or reducible gases and vapors and method of making same is described. The all-solid planar sensor cell has two or more film type electrodes arranged on a non-conductive planar surface of a supportive substrate. Manufacturing the electrochemical sensor with dry ionomer prevents electrode flooding and allows for improved response time upon assembly. The sensor cell contains no liquid electrolyte and is operated in a constant-voltage, potentiostatic or potentiodynamic mode. A high sensitivity to a select gas or vapor is achieved by a three-phase contact area design for a sensing electrode, which provides contact with the solid ionomer electrolyte, as well as the gas sample via diffusion openings or holes that penetrate through the supportive substrate.

Claims

1. A sensor cell for detecting gas comprising:

a substrate;

a sensing electrode in contact with said substrate for detecting gas;

dry ionomer membrane in contact with said substrate and said sensing electrode wherein said dry ionomer membrane acts as an electrolyte; and

an inlet through said substrate for keeping gas in contact with both said dry ionomer membrane and said sensing electrode.

2. The apparatus of claim 1 wherein said dry ionomer membrane is dry sheet Nafion®

.

3. The apparatus of claim 1 wherein the sensor cell is assembled prior to wetting said dry ionomer membrane.

4. The apparatus of claim 1 further including a polymer layer positioned upon said sensing electrode for slowing inputs of gas moving through said inlet onto a surface of said sensing electrode.

5. The apparatus of claim 1 further including a counter electrode in contact with said dry ionomer membrane such that upon wetting said dry ionomer membrane said counter electrode provides an electrical connection to said ionomer membrane so current may be applied to said sensing electrode.

6. The apparatus of claim 1 further including a reference electrode in contact with said dry ionomer membrane such that upon wetting said dry ionomer membrane a reference point is created against which the potential of other electrodes can be measured.

7. The apparatus of claim 1 wherein the dry ionomer membrane is a perfluorosulfonic acid membrane.

8. A method of making an electrochemical sensor for the detection of an analyte in a gas sample comprising:

a) providing a dry ionomer membrane free from liquid droplets;

b) providing a substrate with at least one opening through its surface and a first electrode layer adjacent to said opening;

c) connecting said dry ionomer membrane to said substrate;

d) aligning said at least one opening in said substrate with the first electrode for defining a gas passage; and

e) depositing a second electrode on said substrate for operatively connecting said ionomer membrane, said first electrode, and said second electrode.

9. The method of claim 8 wherein the step of providing a dry ionomer membrane further includes selecting dry sheet Nafion®

.

10. The method of claim 8 further including making said sensor cell prior to wetting said dry ionomer membrane.

11. The method of claim 8 further including positioning a polymer layer upon said sensing electrode for slowing inputs of gas moving through said inlet onto a surface of said sensing electrode.

12. The method of claim 8 where the step of providing a substrate further includes positioning a counter electrode in contact with said dry ionomer membrane such that upon wetting said dry ionomer membrane said counter electrode provides an electrical connection to said ionomer membrane so current may be applied to said sensing electrode.

13. The method of claim 8 where the step of providing a substrate further includes positioning a reference electrode in contact with said dry ionomer membrane such that upon wetting said dry ionomer membrane a reference point is created against which the potential of other electrodes can be measured.

14. The method of claim 8 where the step of obtaining a dry ionomer membrane further includes obtaining a perfluorosulfonic acid membrane.

15. The method of claim 8 further comprising providing a reservoir in contact with said dry ionomer membrane.

16. The method of claim 15 further comprising filling said reservoir with a liquid.

17. The method of claim 15 comprising forming at least one hole in said dry ionomer membrane.

18. The method of claim 17 comprising aligning said at least one hole with the first electrode for defining a gas passage.

19. A method of making an electrochemical sensor for the detection of an analyte in a gas sample comprising:

a) providing a dry ionomer membrane free from liquid droplets;

b) forming at least one hole in said ionomer membrane;

c) providing a substrate with a first electrode layer adjacent to said opening;

d) connecting said dry ionomer membrane to said substrate;

e) aligning said at least one hole with the first electrode for defining a gas passage; and

f) depositing a second electrode on said substrate for operatively connecting said ionomer membrane, said first electrode, and said second electrode.