Co sensor and its fabrication
AssigneeFigaro Engineering Inc.
InventorsYasutaka Ozaki, Sachiyo Suzuki
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Abstract
After sintering of a CO sensor using an SnO2-based metal oxide semiconductor, Ir and Pt are added to the sensor at 5˜500 μg/g SnO2 each, the weight ratio of Ir and Pt being 5˜1/5. This addition is made by impregnating a mixed aqueous solution of an Ir salt and a Pt salt into the SnO2 sintered body and thermally decomposing these salts. Next, an aqueous solution of thiourea is impregnated into the SnO2 sintered body to add thiourea at 0.01˜10 mg/g SnO2 in reduction to simple S element. The temperature and humidity dependency of the CO sensor is suppressed, the CO concentration dependency of the output is increased, and the sensor resistance is brought to a more convenient range of use.
Claims10
A CO sensor for detecting CO including a metal oxide semiconductor comprising a SnO2 gas sensitive material and a means to subject said metal oxide semiconductor to cyclical temperature change,
- wherein an electron-donative S compound having a double-bonded sulfur atom with an oxidation number of −2 is added to said SnO2 at 0.01-10 mg/g SnO2 in reduction to simple S element.
A method of producing a CO sensor comprising sintering SnO2 powder to form a gas sensitive metal oxide semiconductor material, and then adding an electron-donative S compound having a double-bonded sulfur atom with an oxidation number of −2 at 0.01-10 mg/g SnO2 in reduction to simple S element.
A CO sensor for detecting CO including a metal oxide semiconductor comprising a SnO2 gas sensitive material and means to subject said metal oxide semiconductor to cyclical temperature change,
- wherein an electron-donative S compound of at least one member of a group consisting of thiourea, thiosulfuric acid and its derivatives, thiocyanic acid and its derivatives, thiocyanogen and its derivatives is added to said SnO2 at 0.01-10 mg/g SnO2 in reduction to simple S element.
Dependencies are inferred from the claim text.