Proposal of a new structural thermal vacuum sensor with diode-thermistors combined with a micro-air-bridge heater

A new structure thermal vacuum sensor with two pn junction diodes, Th-A and Th-B, as a high sensitive temperature sensor working like a thermistor and a micro heater formed on a micro air‒bridge is proposed. The micro air‒bridge is separated into two regions of A and B. The Th-A measures the temperature of the micro-heater formed on the region A and the Th-B does that of the region B which is connected to the micro-heater with thermal resistance. The diode thermistor, Th-C, formed on the SOI substrate is provided to measure the ambient temperature Tc. Vacuum pressure is measured based on heat dissipation change from the heated micro air‒ bridge to ambient gas. It is demonstrated that this sensor will expand the measuring vacuum range into about two orders or more wider range (2x10-1x10 Pa) than the traditional thermal vacuum sensor, such as Pirani vacuum sensor, and has very fast response and low power consumption.