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MEMS piezoresistive sound detectors have been fabricated using the dissolved wafer process for the first time. The sensors utilize stress compensated PECVD ultra-thin silicon-nitride/oxide membrane together with monocrystalline ion-implanted p ++ silicon piezoresistors to achieve high sensitivity. Tests reveal that sensors with a diaphragm size of 710 µm have a static sensitivity of 1.1 µV VPa −1 with 2% non-linearity over an operating pressure range of 10 kPa. This sensitivity is substantially larger than that of commercially available microfabricated sensors. Furthermore, the new sensor's dynamic response is found to be flat (within ±2.5 dB) over a frequency range extending up to 10 kHz. This paper contributes to existing literature in the field by demonstrating a new way of fabricating capable MEMS piezoresistive pressure sensors, hence adding to the overall versatility of the technology and associated range of applications.

The correspondence principle has been applied to derive the differential equations of viscoelastic Timoshenko beams with external viscous damping. These equations are solved by Laplace transform and boundary conditions are applied to obtain complex frequency equations and mode shapes for beams of any combination of end conditions. For beams without external damping, the correspondence principle can be applied directly to the available solutions of elastic Timoshenko beams. Numerical illustration is given.