Patent ID: 7737700

Claim:
A sensor device for sensing at least one gas in a gaseous atmosphere, comprising: a substrate having first and second surfaces opposing one another; first through nth sensing layers disposed on said substrate and connected to each other in series, said first through nth sensing layers respectively having a first through nth sensing layer electrical resistance, and said first trough nth sensing layers being configured to present differing compositions thereof to said gaseous atmosphere, each of said differing compositions being such as to change a respective one of said first through nth sensing layer electrical resistances in presence of a respective gas; said first through tab sensing layers being disposed electrically connected together in a series connection with each other from said first sensing layer to said nth sensing layer absent intervening resistors; first through (n+1)th electrical terminals disposed on said first surface of said substrate and configured for accepting electrical connections thereto from external to said substrate; first through (n+1)th electrode conductors disposed on said substrate and respectively contacting said first through (n+1)th electrical terminal, said first through (n+1) th electrode conductors being disposed such that, wherein x varies from one to n, said first and said x th electrode conductors are disposed to conduct current passing through said first through said x th sensing layer; a heater resistor disposed on said first surface of said substrate laterally adjacent at least one of said first through nth sensing layers and having a heater resistance, wherein a lateral direction extend parallel the first surface of the substrate; n being at least three, wherein: said heater resistor has first and second heater terminals that arranged in a parallel connection to the series connection of said first through nth sensing layers, said parallel connection being effected by: said first electrical terminal and said first electrode conductor directly connecting to said first sensing layer and said first heater terminal; and said (n+1) th electrical terminal and said (n+1) th electrode conductor connecting to said nth sensing layer and said second heater terminal; and said heater resistance is less than a sum of said first through nth sensing layer electrical resistances.