Media protected surface micromachined leverage beam pressure sensor

In this paper we present the first surface micromachined ultraminiaturized, highly sensitive, pressure sensor that utilizes a force-transducing beam and a 2 µm thick polysilicon pressure sensing diaphragm as an encapsulation layer for high media isolation of the sensing piezoresistor. A beam is attached to the diaphragm at one end and to the cavity at the other end. The pressure-induced diaphragm deflection is transduced to strain in the beam and sensed by a piezoresistive strain-gauge on the beam. The piezoresistor is thus well isolated from the sensing environment. The pressure sensing performance was measured to 0.9 µV V -1 mmHg -1 .