T-shaped resonating beam pressure sensor

A resonant pressure sensor with a provision for incorporating appropriate actuation and detection mechanism using fully surface micromachined process is presented in this paper. The pressure sensing element is a T-shaped resonating beam encapsulated beneath a polysilicon rectangular diaphragm and fully enclosed in a sealed vacuum cavity. This design enables high pressure sensitivity, miniature chip size and as well as good environmental isolation. The proposed structure is evaluated for pressure sensitivity theoretically and numerically using MEMS CAD tool CoventorWare. The pressure sensitivity of the sensor with a T-shaped 1.2 μm thick beam is found to be 10.2%/bar with the beam resonance frequency of about 792 kHz.