Golay-cell type of miniaturized infrared sensor using Si-diaphragm

A miniaturized capacitance-detection type of infrared sensor based on the principle of the Golay-cell has been developed using silicon micromachining. The sensor has a tiny gas chamber with thin silicon diaphragm forming one side of electrodes of a parallel planar capacitor. Illuminated infrared light heats the gas in the chamber and then deflection of the diaphragm induced by expansion of the gas is detected as capacitance change of the capacitor. The chamber of our device is completely sealed and can be filled by various kinds of gas. The sensor containing a certain gas shows a specific response of the intrinsic spectrum of absorption of ambient gas. Selective detectability of ambient gas has been confirmed using various sensors containing different gases.