Development of a micromachined accelerometer for particle acceleration detection

We are reporting on the design, fabrication, and experimental results for a micromachiend accelerometer that is intended to be used in the detection of acoustic signals, where the main requirements include low noise, wide bandwidth, and high linearity. The device design requirements are discussed and analytically modelled. Microfabrication details to build prototypes are provided in detail. The final device structure employs membrane as the suspension mechanism and a proof-mass made from the entire thickness of a wafer that is suspended above a fixed electrode. The proposed manufacturing process allows for precise and independent control of the structural components of the device and the capacitive gap. Prototype devices were fabricated and characterized. Measurements on the device performance demonstrate a 0.6μg/Hz noise floor with resonance frequency of 5.2 kHz, sensitivity of ∼0.9 pF/g, and open-loop dynamic range of higher than 145 dB while operating at atmospheric pressure. The device meets the requirements for measuring sonar signals in the range of 50 Hz to 5 kHz under low environmental noise conditions.