A surface micromachined resonant beam pressure sensor

The first entirely surface micromachined resonant beam pressure sensor is presented. Using a fully surface micromachined process an encapsulated beam resonant pressure sensor with a pressure sensitive diaphragm of 100/spl times/150/spl times/2 /spl mu/m has been fabricated. The resonating beam is fully enclosed inside the reference vacuum cavity formed beneath the diaphragm. The new design enables high pressure sensitivity and a miniature chip size, essential for sensors such as catheter mounted intravascular blood pressure sensors. The pressure sensitivity is measured to 3.2%/bar with a beam resonance frequency at about 700 kHz.