Conductimetric gas sensor

• US 4,473,456 A
• Filed: 03/22/1982
• Issued: 09/25/1984
• Est. Priority Date: 04/08/1981
• Status: Expired due to Fees

• Current Assignee: National Research Development Corporation 66-74 Victoria Street London SW1 England
• Original Assignee: National Research Development Corporation
• Inventors: Hawkins, Peter
• Primary Examiner(s): Tung, T.
• Assistant Examiner(s): Chapman, Terryence
• Application Number:
  US06/360,769
• Time in Patent Office: 918 Days
• Field of Search: 204/195 P, 204/195 M, 204/195 R, 204/1 T, 204/1 K, 204/415, 324/439, 324/459
• US Class Current: 204/403.1
• CPC Class Codes: G01N 27/4162 investigating the composition of gases, by the influence exerted on ionic conductivity in a liquid conductometry in general G01N27/06; amperometric gas sensors G01N27/404

Abstract

A conductimetric gas sensor consists of a ptfe body forming an electrolytic cell; two threaded silver electrodes screwed into the ptfe body and bridged by a layer of a hydrophilic gel in contact with an electrolyte in the cell; a reservoir for supplying deionized water to the cell, so that the volume of water between the electrodes is maintained; and a gas-permeable hydrophobic layer through which the hydrophilic gel can be exposed to the gas.

Claims

1. A conductimetric gas sensor, for measurement of gas concentration in a static or flowing fluid, comprising:

an electrolytic cell for containing an electrolyte of deionised water;

a gas-permeable hydrophobic layer through which a gas to be sensed can contact said electrolyte contained in the cell;

two spaced electrodes within the cell and both closely adjacent the gas-permeable hydrophobic layer;

between the electrodes and the hydrophobic layer, a layer of a hydrophilic gel of polymeric material; and

a reservoir supplying deionised water to the cell, so that the volume of water between the electrodes is maintained.

2. A sensor according to claim 1 in which the hydrophilic gel is polyacryloylmorpholine.

3. A sensor according to claim 1 in which the gas permeable hydrophobic layer is polytetrafluoroethylene film.

4. A sensor according to claim 1 in which the electrolyte cell is a polytetrafluoroethylene body and the two electrodes are threaded silver rods which are screwed into said body.

5. A sensor according to claim 1 further comprising conductivity sensing means arranged to sense the electrical conductivity of the electrolyte in the cell between the electrodes.

6. A sensor according to claim 1 in which the hydrophilic gel includes an enzyme material capable of reducing the response time of the sensor to both increases and decreases in gas concentration.

7. A sensor according to claim 6 in which the enzyme is carbonic anhydrase.