7 May 2012 Relation between charge on free electrodes and the response of electrostatic MEMS actuators and sensors
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Stability is an important factor in the study of electrostatic MEMS switches and sensors. Their response is signicantly improved by either applying a large dc bias or by depositing a prescribed value of charge on the oating electrodes. This charge is related to the pull-in voltages. Measurement of charge without causing loading is recommended; so instead of incorporating any eld operated transistor circuitry for this purpose, methods are developed to relate the charge magnitude to the dynamical response of the actuators. Elata et al. developed ecient and reliable ways of charge monitoring without causing loading to the device. These methods rely on energy of the system instead of performing integration in the time domain. Based on their work, this paper examines the alterations in the dynamic response of actuators. The positive and negative pull-in voltages in the voltage displacement plane are symmetrically located with respect to charge on the oating electrode. This fact is exploited to carry out indirect charge measurement from the average of the two pull-in values. A regression scheme is proposed that predicts the charge from the voltage shift based on limited measurements of capacitance of the actuator.
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Sudarshan R. Nelatury, Sudarshan R. Nelatury, Robert Gray, Robert Gray, } "Relation between charge on free electrodes and the response of electrostatic MEMS actuators and sensors", Proc. SPIE 8373, Micro- and Nanotechnology Sensors, Systems, and Applications IV, 83732P (7 May 2012); doi: 10.1117/12.919391; https://doi.org/10.1117/12.919391

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