Adam B Miller

US Patent:

59893982, Nov 23, 1999

Filed:

Nov 14, 1997

Appl. No.:

8/970837

Inventors:

Daniel A. Young - Gurnee IL
Adam Moya - Albuquerque NM
Chowdary R. Koripella - Albuquerque NM
Jeff Naber - Dearborn MI
Neil Adams - Novi MI
Craig Markyvech - Romulus MI
Adam Miller - Chicago IL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G01N 2726
G01N 27419

US Classification:

204424

Abstract:

A calorimetric hydrocarbon gas sensor (10) includes an electrochemical oxygen pump (18), a sensing element (12), and a multi-layered substrate (26) separating the sensing element (12) from the electrochemical oxygen pump (18). The multi-layered substrate (26) includes a plurality of overlying insulating layers, in which at least one intermediate layer (60) supports a first primary heater (58), and in which another intermediate layer (52) supports a temperature compensation heaters (50a, 50b). The primary heater (58) functions to maintain the calorimetric hydrocarbon gas sensor (10) at a constant, elevated temperature, while the active compensation heater (50a) functions to maintain substantially equal temperatures as determined by the thermometers (46a, 46b) located on an intermediate layer (48) overlying the compensation heaters (50a, 50b). Control circuitry is integrated with power measurement circuitry to measure differences in the heat produced by the compensation heater (50a) and the thermometer (46a) in an active region (100), and the heat produced by the compensation heater (50b) and the thermometer (46b) in a reference region (102).