Patent ID: 7565827

Claim:
A gas sensor for sensing a gas stream constituent, the gas sensor comprising: (a) a thermally conductive, electrically insulative substrate; (b) a first gas-sensing element mounted on said substrate, said first gas-sensing element capable of sensing said constituent in a first concentration range; (c) a reference element mounted on said substrate, said reference element and said first gas-sensing element having congruent electrical properties, said reference element insensitive to said constituent; (d) a heating element mounted on said substrate such that a uniform temperature environment is effected around said first gas-sensing element and said reference element; (e) a temperature-sensing element mounted on said substrate and in thermal connection with said first gas-sensing element and said reference element; (f) a second gas-sensing element mounted on said substrate capable of sensing said constituent in a second concentration range such that said heating element imparts at least some heat to said second gas-sensing element; wherein said temperature-sensing element is thermally connected to said heating element and wherein said first gas-sensing element, said reference element, said heating element, said temperature-sensing element and said second gas-sensing element are arranged in a nested geometric configuration on said substrate.