Silicon-based thermal conductivity detector for gas sensing and gas chromatography

Abstract

We present a novel thermal conductivity detector (TCD) for gas sensing and gas chromatography. Its original architecture is based on a suspended membrane on top of which a heating element made of titanium nitride and a separated sensing element made of amorphous silicon are deposited. These sensors are micro-fabricated from 200 mm silicon wafers and tested on a gas bench. When used as a standalone gas sensor, they reach a theoretical detection limit (3σ) of 13 ppm for carbon dioxide in the air and exhibit a signal-to-noise ratio 4 times higher than that of conventional platinum TCDs.