US4887455A
Expired / Lapsed
US
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Gas sensor
Assignee: Osmetech PLC
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Filing: 1988-04-05
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Granted: 1989-12-19
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Expires: 2008-04-05
Abstract
Abstract A gas sensor has a layer of a semiconductor organic polymer, such as polypyrrole which is exposed to a gas to be detected. An alternating electric signal of varying frequency is applied to the sensor by an analyser, which detects the change in impedance characteristics of the sensor. The characteristics obtained are compared by microcomputer with reference characterisitcs stored in a memory. The resulting difference spectra depend on the gas in contact with the sensor and so the gas can be detected.
Inventors
- 👤 Peter A. Payne
- 👤 Jon G. Bartlett
- 👤 Natalie K. Harris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:41
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/125; G01N27/126; G01N27/122
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
55 words
A gas sensor for detecting the presence of a gas, the sensor comprising: a layer of semiconducting organic polymer; means for applying an alternating electric signal to the layer; means for varying the frequency of said signal; and means for detecting the variation in impedance characteristics of said layer in the presence of said gas.
Claim 2
Dependent Claim
55 words
A gas sensor for detecting the presence of a gas, the sensor comprising: a layer of semiconducting organic polymer; means for applying an alternating electric signal to the layer; means for varying the frequency of said signal; and means for detecting the variation in impedance characteristics of said layer in the presence of said gas.
Claim 3
Dependent Claim
47 words
A sensor according to claim 1, wherein said means for detecting the variation comprises, means for storing reference impedence variation characteristics, and means for comparing said reference variation characteristic with the variation in impedence characteristics of said layer in the presence of said gas to be detected.
Claim 4
Dependent Claim
24 words
A sensor according to claim 1, wherein said semiconducting organic polymer is selected from the group consisting of polypyrrole, poly-2-chloroaniline, poly-2-acetonitrile, polyindole, and poly-2-isobutylthiazole.
Claim 5
Independent Claim
49 words
A method of detecting a gas comprising: applying an alternating electric signal to a layer of a semiconducting organic polymer, said layer being exposed to said gas; varying the frequency of said alternating signal; and investigating the variation in impedance characteristics of said layer, thereby to detect said gas.
Claim 6
Independent Claim
49 words
A method of detecting a gas comprising: applying an alternating electric signal to a layer of a semiconducting organic polymer, said layer being exposed to said gas; varying the frequency of said alternating signal; and investigating the variation in impedance characteristics of said layer, thereby to detect said gas.
Claim 7
Dependent Claim
58 words
A method according to claim 4, wherein the step of investigating the variation in impedence comprises: obtaining a reference variation by determining the variation in impedence characteristic of said layer when exposed to a reference gas, and comparing said reference variation with the variation in impedence characteristic of said layer when exposed to said gas to be detected.
Claim 8
Dependent Claim
17 words
A method according to claim 5, wherein the minimum frequency of said frequency variation is 1 MHz.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-18 | 1993-06-19 | 1993-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-18 | 1997-06-19 | 1997-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-18 | 2001-06-19 | 2001-12-19 | $7700.00 | Window Closed / Lapsed |