Patent ID: 7141859

Claim:
A device, comprising: a conductometric porous silicon gas sensor including a monolithic silicon substrate having a porous silicon layer and a protective layer, wherein the protective layer is disposed on top of the silicon substrate and adjacent to the porous silicon layer, wherein the protective layer is selected from a silicon carbide layer, a silicon nitride layer, a polymer layer, a silicon oxynitride layer, an insulating dielectric film, a ceramic layer, a photoresist layer, a polyimide layer, and combinations thereof, wherein the porous silicon layer has a first portion and a second portion that are not contiguous, wherein the protective layer has a first portion and a second portion that are not contiguous, wherein the first portion of the protective layer is contiguous with the first portion of the porous silicon layer, wherein the second portion of the protective layer is contiguous with the second portion of the porous silicon layer, wherein a first metal layer is disposed on the first portion of the porous silicon layer and the first portion of the protective layer to form a first contact, wherein a second metal layer is disposed on the second portion of the porous silicon layer and the second portion of the protective layer to form a second contact, and wherein the conductometric porous silicon gas sensor is operative to transduce the presence of a gas into an impedance change across the first contact and the second contact, wherein the impedance change correlates to the gas concentration.