A surface-micromachined resonant-beam pressure-sensing structure

The first study on an entirely surface-micromachined resonant-beam pressure sensor is presented. Using a fully surface-micromachined process, an encap sulated beam resonant pressure-sensor structure with a pressure-sensitive d iaphragm of 100 x 150 x 2 mum has been fabricated. The resonating beam is f ully enclosed inside the reference vacuum cavity formed beneath the diaphra gm. The new design enables high pressure sensitivity and a miniature chip s ize, essential for sensors such as catheter-mounted intravascular blood pre ssure sensors. The pressure sensitivity is measured at 3.2 %/bar with a bea m resonance frequency of about 700 kHz.