US5222388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nitrogen dioxide detection
Assignee: United States Department of Energy
•
Filing: 1991-03-19
•
Granted: 1993-06-29
•
Expires: 2011-03-19
Abstract
Abstract Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.
Inventors
- 👤 Dipen N. Sinha
- 👤 Stephen F. Agnew
- 👤 William H. Christensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:15
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/125; G01N27/126; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0036; G01N33/0037; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
42 words
A method for detection of nitrogen dioxide in a gas comprising: a. exposing a sensing element consisting of polystyrene to said gas; b. imposing an electrical potential across said sensing element; and c. measuring the conductance or resistance of said sensing element.
Claim 2
Independent Claim
42 words
A method for detection of nitrogen dioxide in a gas comprising: a. exposing a sensing element consisting of polystyrene to said gas; b. imposing an electrical potential across said sensing element; and c. measuring the conductance or resistance of said sensing element.
Claim 3
Dependent Claim
23 words
The method of claim 1 further including converting said conductance or resistance value to an amount of nitrogen dioxide present in said gas.
Claim 4
Dependent Claim
107 words
Apparatus for detection of nitrogen dioxide in a gas comprised of: a,. sensing element consisting of polystyrene having at least one pair of opposing surfaces, where the conductance and resistance of said sensing element do not vary in response to the presence in said gas of varying amounts of water vapor; b. a first electrode having at least one surface in contact with a first of said sensing element opposing surfaces; c. a second electrode having at least one surface in contact with a second of said sensing element opposing surfaces; and d. means for measuring the conductance or resistance of said sensing element between said electrodes.
Claim 5
Dependent Claim
107 words
Apparatus for detection of nitrogen dioxide in a gas comprised of: a,. sensing element consisting of polystyrene having at least one pair of opposing surfaces, where the conductance and resistance of said sensing element do not vary in response to the presence in said gas of varying amounts of water vapor; b. a first electrode having at least one surface in contact with a first of said sensing element opposing surfaces; c. a second electrode having at least one surface in contact with a second of said sensing element opposing surfaces; and d. means for measuring the conductance or resistance of said sensing element between said electrodes.
Claim 6
Dependent Claim
25 words
The apparatus of claim 3 further including means for converting said conductance or resistance value to an amount of nitrogen dioxide present in said gas.
Claim 7
Dependent Claim
16 words
The apparatus of claim 3 where said electrodes are interdigitated electrodes and are encapsulated in polystyrene.
Claim 8
Dependent Claim
28 words
The apparatus of claim 3 where said electrodes are interdigitated electrodes disposed on an inert substrate and polystyrene is deposited on said substrate between fingers of said electrodes.
Claim 9
Dependent Claim
22 words
The apparatus of claim 3 where said sensing element is a thin film sandwiched between said first electrode and said second electrode.
Claim 10
Dependent Claim
29 words
The apparatus of claim 3 further including a housing containing said sensing element and said electrodes where said housing has a gas inlet nozzle and a gas outlet nozzle.
Claim 11
Dependent Claim
25 words
The apparatus of claim 3 where said electrodes are treated with a chemical bonding agent to prevent separation of said sensing element from the electrodes.
Claim 12
Dependent Claim
24 words
The apparatus of claim 3 where said electrodes are porous such that nitrogen dioxide gas can migrate through the electrodes to said sensing element.
References Cited (Backward Citations)
US2728831A
Cited
US2937524A
Cited
US3924219A
Cited
US4142400A
Cited
US4264331A
Cited
US4236307A
Cited
US4388342A
Cited
US4225842A
Cited
JPS57127837A
Cited
US4563893A
Cited
US4499240A
Cited
US4579921A
Cited
JPS60178346A
Cited
JPS60256043A
Cited
GB2166244A
Cited
JPS61147145A
Cited
US4755473A
Cited
US4681855A
Cited
US4869874A
Cited
US5049808A
Cited
US5018380A
Cited
US5071626A
Cited
US5135637A
Cited
US5085776A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-06-28 | 1996-12-28 | 1997-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-28 | 2000-12-28 | 2001-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-28 | 2004-12-28 | 2005-06-29 | $7700.00 | Window Closed / Lapsed |