Gas sensor

• US 5,234,567 A
• Filed: 01/23/1992
• Issued: 08/10/1993
• Est. Priority Date: 01/25/1991
• Status: Expired due to Fees

• Current Assignee: City Technology Ltd. (Honeywell International Inc.)
• Original Assignee: City Technology Ltd. (Honeywell International Inc.)
• Inventors: Hobbs, Bryan S., Chan, Yat S.
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Bell, Bruce F.
• Application Number:
  US07/824,510
• Time in Patent Office: 565 Days
• Field of Search: 204/412, 204/415, 204/153.15, 204/153.17, 204/422, 204/424
• US Class Current: 204/415
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/0054 Ammonia
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

An electrochemical gas sensor for sensing an alkaline gas such as ammonia. The sensor comprises at least sensing and counter electrodes provided in a cell containing an aqueous electrolyte, the cell further including a diffusion barrier to restrict the access of gas to the cell, and a chemical species with which the gas reacts in use to form a product which is more electrochemically active than the gas. The chemical species is one of iodine, Nesslers reagent and a solution of manganous and silver nitrates.

Claims

1. An electrochemical gas sensor for sensing an alkaline gas, the sensor comprising at least sensing and counter electrodes provided in a cell containing an aqueous electrolyte, the cell further including a diffusion barrier to restrict the access of gas to the cell, and a chemical species with which the gas reacts ensue to form a product which is more electrochemically active than the gas, wherein said chemical species is one of:

a) iodine;

b) Nesslers reagent; and

c) a solution of manganous and silver nitrates.

2. A sensor according to claim 1 for detecting ammonia, wherein said chemical species is iodine.

3. A sensor according to claim 2, wherein said iodine is bound to another compound to reduce its volatility.

4. A sensor according to claim 3, wherein said iodine is bound chemically to starch.

5. A sensor according to claim 1, wherein said sensor further comprises a permeation device containing an iodine source so as to provide a controlled release of iodine into the electrolyte.

6. A sensor according to claim 5, wherein said iodine source comprises solid iodine.

7. A sensor according to claim 1, wherein said diffusion barrier is at least one of a gas phase diffusion barrier and a Knudsen barrier.

8. A sensor according to claim 1, further comprising a reference electrode.