Chemical sensor for carbon monoxide detection
First Claim
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1. A sensor for detecting CO in a flowing gas stream comprising:
- (a) a surface layer comprising Cu1+x Mn2-x O4-y, said surface layer having a surface layer resistance which changes as a function of CO concentration;
(b) means for measuring said surface layer resistance on said surface layer;
(c) means for determining any difference between said measured surface layer resistance in the absence of said flowing gas stream at said surface layer and in the presence of said flowing gas stream at said surface layer; and
(d) means for relating said difference to CO concentration in said flowing gas stream.
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Abstract
A ceramic sensor (12) comprising a thin film (14) of Cu1=x Mn2-x O4-y is provided that quantitatively measures the partial pressure of CO gas in a flowing system (22). The sensor is specific to CO gas and is negligibly affected by the presence of the common automobile exhaust vapors NO, H2 O, and CH4, within the operational temperature range from about 250° to 450° C. The CO sensor of the invention has other applications, such as monitoring CO levels in laboratories, mines, and industrial smoke stacks, and may be used in environments up to about 700° C.
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Citations
11 Claims
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1. A sensor for detecting CO in a flowing gas stream comprising:
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(a) a surface layer comprising Cu1+x Mn2-x O4-y, said surface layer having a surface layer resistance which changes as a function of CO concentration; (b) means for measuring said surface layer resistance on said surface layer; (c) means for determining any difference between said measured surface layer resistance in the absence of said flowing gas stream at said surface layer and in the presence of said flowing gas stream at said surface layer; and (d) means for relating said difference to CO concentration in said flowing gas stream. - View Dependent Claims (2, 3, 4)
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5. A CO detector system for detecting CO in a flowing gas stream passing through a catalytic converter comprising:
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(a) two CO sensors, one sensor located upstream of said catalytic converter and the other sensor located downstream of said catalytic converter, each CO sensor comprising (1) a surface layer comprising Cu1+x Mn2-x O4-y, supported on a substrate, aid surface layer having a surface layer resistance which changes as a function of CO concentration on aid surface layer and (2) means for measuring the surface layer resistance of said surface layer; (b) comparator means to receive said measured surface layer resistance from each CO sensor and to compare said measured resistances; and (c) output means to provide a warning signal if the difference between said measured resistances exceeds a pre-set limit or to make adjustments in engine air/fuel ratio. - View Dependent Claims (6, 7, 8)
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9. A method for measuring the CO concentration in a flowing gas stream comprising:
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(a) causing said gas stream to flow over a surface comprising Cu1+x Mn2-x O4-y,said surface layer having a surface layer resistance which changes as a function of CO concentration on said surface layer; (b) measuring said surface layer resistance on said surface layer; (c) determining any difference between said measured surface layer resistance in the absence of said flowing gas stream at said surface layer and in the presence of said flowing gas stream at said surface layer; and (d) relating said difference to CO concentration in said flowing gas stream. - View Dependent Claims (10, 11)
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Specification