Arun Balaji Bhaskar, Girish Krishnan, and G.K. Ananthasuresh
ABSTRACT: This paper reports a novel, low-cost, moderately sensitive, meso-scale accelerometer fabricated with spring steel foil and equipped with a Hall-effect proximity sensor. The Hall-effect sensor is small in size, and is suitable for miniature proximity sensing applications. Since the sensitivity of a Hall-effect sensor is low, we attach a displacement-amplifying compliant mechanism (DaCM) to the proof-mass of the accelerometer to increase the overall sensitivity without compromising on its natural frequency. The displacement of the output of the DaCM is measured using the Hall-effect sensor. The voltage-change in the sensor is calibrated for the applied acceleration. The device is fabricated using wire-cut electro-discharge machining (EDM) of ENJ42/AISI1080 spring steel resulting in an overall size of 60 mm × 60 mm × 10 mm including the Hall-effect sensor. Testing revealed that the accelerometer can detect acceleration signals as small as 14 mg. The measured sensitivity of the accelerometer is 71 mV/g. Finite element simulation of the accelerometer showed that its natural frequency is 50 Hz, which is around 40% greater than an accelerometer with similar sensitivity without a DaCM. The design proposed here can be miniaturized further and fabricated with silicon microfabrication processes for enhanced sensitivity and resolution.
KEYWORDS: Accelerometers, Hall-effect sensor, Wire-EDM, and Displacement-amplifying Compliant Mechanism
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