A Thermal Absolute-pressure Sensor With On-chip Digital Front-end Processor

Thermal conductivity absolute-pressure sensors are widely used in vacuum systems.1 Their operation is based on the pressure dependence of the heat transfer from a suspended hot filament through a gas. The filament temperature and IV curve are dependent on the heat transfer and hence on the gas pressure. This mechanism has been studied thoroughly by V. Ubisch and others.2 Recently, microbridge resistor structures consisting of a resistive doubly-supported beam suspended above the substrate have been used to detect absolute gas pressure.3 The pressure-dependent heat transfer in these structures occurs across the gap between the beam and the substrate.