Thermal microsensor with a.c. heating for gas-pressure measurements

Abstract A method for gas-pressure measurements by means of a micromachined thermal sensor is described. A 0.15 μm thick silicon nitride membrane with dynamically changed dissipated power serves as a gas heater. Theoretical and experimental results of the sensor sensitivity in a frequency range of modulated dissipated power from 20 Hz to 1 kHz are presented. A resolution of 0.2 torr is estimated at atmospheric pressure.