US4039941A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas sensor
Assignee: SRI International Inc
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Filing: 1975-05-09
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Granted: 1977-08-02
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Expires: 1995-05-09
Abstract
Abstract A gas sensor is provided here comprising a semi-conductor support coated with a material which reacts with a specific gas as a result of which it exchanges electrons with the support. By measuring the resulting change in conductivity of the support, one can detect the presence of the particular gas as well as its concentration.
Inventors
- 👤 Stanley R. Morrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:49
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/16
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
72 words
A gas detector comprising: a semiconductor support which is substantially nonreactive to a gas to be detected, a surface additive means which is a catalyst deposited solely on said semiconductor support surface and in pores in said surface, for exchanging electrons with said semiconductor in the presence of said gas to be detected to change the conductivity of said semiconductor, and means for detecting the change in conductivity of said semiconductor support.
Claim 2
Dependent Claim
72 words
A gas detector comprising: a semiconductor support which is substantially nonreactive to a gas to be detected, a surface additive means which is a catalyst deposited solely on said semiconductor support surface and in pores in said surface, for exchanging electrons with said semiconductor in the presence of said gas to be detected to change the conductivity of said semiconductor, and means for detecting the change in conductivity of said semiconductor support.
Claim 3
Dependent Claim
22 words
A gas detector as recited in claim 1 wherein said semiconductor support is NiO:Li and said surface additive means is sulfanilic acid.
Claim 4
Dependent Claim
23 words
A gas detector as recited in claim 1 wherein said semiconductor support is titanium dioxide and said surface additive means is vanadium pentoxide.
Claim 5
Dependent Claim
70 words
Apparatus for detecting a predetermined gas comprising: a compressed pellet of semiconductor powder particles which are not reactive to said gas impregnated with a surface additive, which is a catalyst which is deposited solely on the surface and in pores of said powder particles, which in the presence of said gas exchanges electrons with said semiconductor powder particles, and means for measuring the change of conductivity of said compressed pellet.
Claim 6
Dependent Claim
70 words
Apparatus for detecting a predetermined gas comprising: a compressed pellet of semiconductor powder particles which are not reactive to said gas impregnated with a surface additive, which is a catalyst which is deposited solely on the surface and in pores of said powder particles, which in the presence of said gas exchanges electrons with said semiconductor powder particles, and means for measuring the change of conductivity of said compressed pellet.
Claim 7
Dependent Claim
25 words
Apparatus as recited in claim 4 wherein said apparatus includes means for heating said compressed pellet and gas to be detected to a predetermined temperature.
Claim 8
Independent Claim
81 words
A method of making a detector for a predetermined gas comprising: depositing a surface additive which is a catalyst solely over the surface and in pores of powder particles of a semiconductor material which is not reactive with said gas, which surface additive, in the presence of said gas, can exchange electrons with said semiconductor support, compressing said powder particles upon which said surface additive has been deposited to form a pellet, and connecting a conductivity measuring means to said pellet.
Claim 9
Independent Claim
81 words
A method of making a detector for a predetermined gas comprising: depositing a surface additive which is a catalyst solely over the surface and in pores of powder particles of a semiconductor material which is not reactive with said gas, which surface additive, in the presence of said gas, can exchange electrons with said semiconductor support, compressing said powder particles upon which said surface additive has been deposited to form a pellet, and connecting a conductivity measuring means to said pellet.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-01 | 1981-01-31 | 1981-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-01 | 1985-01-31 | 1985-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-01 | 1989-01-31 | 1989-08-02 | $7700.00 | Window Closed / Lapsed |