Optimisation Of Filament Geometry For Gas Sensor Application

S. Gidon, M. Brun, and S. Nicoletti
CEA Minatec, Optronic Department, Grenoble, France
Published in 2010

Monitoring of indoor CO2 concentration is of particular interest to detect room occupancy in order to optimise power consumptions of building. One technological approach is to use optical detection using specific absorption lines of CO2 molecules in the infrared domain close to 4.2 μm. Key features for a wider use in public and private buildings are power consumption and price. Such optical sensors include a detector, typically a micro-bolometer, an IR source – such as a hot filament – and a filter to select the interesting band in the black body spectrum of the emitter. All these components can be made in well known planar Si technology using MEMS approach. To fabricate a free-standing microhotplate, we chose Si3N4/SiO2 as supporting layer and TiN/Pt/TiN for heater layer.

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