RESONANT MICROBEAM ACCELEROMETERS

摘要: Resonant microbeam strain-sensing elements have been combined with a highly symmetric multiwafer silicon microstructure to fonn the first micromachined accelerometer polysilicon resonant pickoff. The accelerometers uniquely combine bulk micromachining advanced surface techniques and multiple-wafer structure produce an all-silicon acceleration sensor capsule direct-to-digital frequency output. microbeams are fabricated from thin films of mechanical-grade integral polysi1:icon vacuum encapsulation, electrostatic drive piezoresistive sense. features dual open-web suspension system formed monolithically proof mass frame. Silicon caps provide squeeze film gas damping, overrange protection, environmental protection. Initial devices scale factors greater than 700 Hz./g on +20-g device base 524 kHz. Root Allan variances below 0.1 Hz seven-day stability measurements less 2 ppm tiase indicate that milli-g micro-g sensitivities attainable.