Pressure micro-sensor based on Radio-Frequency transducer

A new type of pressure micro-sensors is reported in this communication. It is based on the use of a Radio-Frequency transducer. The pressure to be measured is applied on a silicon membrane located in the close vicinity of a coplanar millimeter-wave resonator: when varying the applied pressure, the distance between the membrane and the planar resonator is modified and consequently, the resonant frequency of the cavity changes. From the measurement of the resonant frequency the applied pressure is derived. Coplanar technology has been chosen because, on the one hand, it confers a better sensitivity to the pressure cell compared to the microstrip technology and, on the other hand, it does not require backside technological processing. In the millimeter frequency range, HFSS simulation results predict a good sensitivity of the resonant frequency to the applied pressure. Very first prototypes of the original pressure micro-sensor based on Radio-Frequency transducer were micro-machined and the obtained measured performances are presented here. Experimental results confirm the expected sensitivity of this new type of pressure micro-sensors.