Hybrid film type sensor

• US 20050126930A1
• Filed: 11/12/2004
• Published: 06/16/2005
• Est. Priority Date: 11/19/1999
• Status: Active Grant

• Current Assignee: PerkinElmer LAS, Inc. (Perkinelmer Incorporated)
• Original Assignee: PerkinElmer LAS, Inc. (Perkinelmer Incorporated)
• Inventors: Prohaska, Otto J., LaConti, Anthony B., Manoukian, Mourad, Giner, Jose D.
• Granted Patent: US 7,601,250 B2
• Time in Patent Office: Days
• US Class Current: 205/779.500
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 27/4074 for detection of gases other than oxygen
• CPC Class Codes: G01N 33/004 CO or CO2

Abstract

A miniaturized gas sensor comprised of thick- or thin-film type electrodes, on a non-conductive supportive substrate, and in contact with a solid ionomer electrolyte, for the detection of toxic gases, i.e., carbon monoxide, and other oxidizable or reducible gases and vapors 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. The electrodes are discrete and in intimate contact with the same solid polymer ionomer membrane. 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 novel 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 gases comprising:

a substrate having a first surface and an opposite second surface;

a sensing electrode;

said sensing electrode in contact with said second surface;

an opening extending from said first surface to said second surface proximate to said sensing electrode for controlling a gas flow; and

a gas diffusion membrane in contact with and extending from said first surface to said sensing electrode.

4. The sensor cell of claim 1 whereby said gas diffusion membrane is humidified by an aqueous material.

5. The sensor cell of claim 1 incorporated into a gas sensing instrument.

6. The sensor cell of claim 1, further including a counter electrode.

7. The sensor cell of claim 1 wherein said sensor cell is electronically controlled by a constant voltage source connected to said sensing electrode and an electrochemically reversible counter electrode also acting as a reference electrode.

8. The sensor cell of claim 1 further comprising a microprocessor for real time data readout, data storage and retrieval, and remote data transmission.

9. The sensor cell of claim 6 wherein said sensor cell is electronically controlled in a 2 electrode sensor configuration.

10. The sensor cell of claim 6, further including a reference electrode.

11. The sensor cell of claim 10 whereby at least one of said sensing, counter, or reference electrodes contains a fluorocarbon-bonded particulate catalyst which is bonded to said ionomer membrane.

12. The sensor cell of claim 11 whereby said fluorocarbon-bonded particulate catalyst is coated with a polymeric thin gas-permeable diffusion layer film.

13. The sensor cell of claim 10 whereby at least one of said sensing, counter, or reference electrodes contains an ionomer-bonded particulate catalyst which is bonded to said ionomer membrane.

14. The sensor cell of claim 13 whereby said ionomer-bonded particulate catalyst is coated with a polymeric thin gas-permeable diffusion layer film.

15. The sensor cell of claim 10 wherein said sensing, counter, and reference electrodes comprise a material selected from the group consisting of Pt, Au, C, platinized Pt, and platinized Au.

16. The sensor cell of claim 10 wherein said sensor cell is electronically controlled in a 3 electrode sensor configuration.

17. The sensor cell of claim 10 wherein said sensor cell is electronically controlled by a potentiostatic circuit connected to said sensing, counter and reference electrodes.

18. The sensor cell of claim 10 wherein said sensor cell is electronically controlled by a potentiodynamic circuit connected to said sensing, counter and reference electrodes.

2. (canceled)

3. (canceled)

19. A sensor cell for detecting gases comprising:

a substrate having a first surface and an opposite second surface;

a sensing electrode;

said sensing electrode in contact with said second surface;

an opening extending from said first surface to said second surface proximate to said sensing electrode for controlling a gas flow; and

a gas diffusion membrane being of polymeric material in contact with and extending from first surface to said sensing electrode.

20. The sensor cell in claim 19, wherein said gas diffusion membrane is a non-electrolytic material.

22. The sensor cell of claim 19, wherein said gas diffusion membrane is made of polyethylene.

21. (canceled)

23. (canceled)

24. A method for detecting gases comprising the steps of:

providing a substrate having a first surface and a second surface;

placing an electrode in contact with the substrate;

extending an opening from the first surface to the second surface proximate to the sensing electrode for controlling a gas flow;

placing a gas diffusion membrane within the opening and between the gases to be detected and the sensing electrode; and

calculating a thickness of the gas diffusion membrane based upon a parameter selected from the group consisting of a material of the gas diffusion membrane, a difference in partial pressure of the gas across the gas diffusion membrane, a permeability coefficient of the gas diffusion membrane, and combinations thereof.

25. The method of claim 24, further comprising the step of humidifying the gas diffusion membrane with an aqueous material.

26. The method of claim 24, further comprising the step of electrically controlling the sensor cell by a constant voltage source connected to the sensing electrode and an electrochemically reversible counter electrode also acting as a reference electrode.

27. A method for detecting gases comprising the steps of:

providing a substrate having a first surface and a second surface;

placing an electrode in contact with the substrate;

extending an opening from the first surface to the second surface proximate to the sensing electrode for controlling a gas flow;

placing a gas diffusion membrane of polymeric material within the opening and between the gases to be detected and the sensing electrode; and

calculating a thickness of the gas diffusion membrane based upon a parameter selected from the group consisting of a material of the gas diffusion membrane, a difference in partial pressure of the gas across the gas diffusion membrane, a permeability coefficient of the gas diffusion membrane, and combinations thereof.