Using electric actuation and detection of oscillations in microcantilevers for pressure measurements |
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Authors: | Gayatri Keskar Bevan Elliott Jay Gaillard Malcolm J. Skove Apparao M. Rao |
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Affiliation: | aSchool of Materials Science and Engineering, Clemson University, Clemson, SC 29634, United States;bDepartment of Physics and Astronomy and Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634, United States |
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Abstract: | Response characteristics of a microcantilever, such as resonant frequency, amplitude, phase and quality factor, can be used for absolute pressure measurements in the range of 10−4 to 103 Torr. To this end, it would be very convenient to have the resonance of the microcantilever actuated and detected electrostatically. Herein, we report the nonlinear dynamics of microcantilevers under varying pressure and different gases using the harmonic detection of resonance (HDR) technique [J. Gaillard, M.J. Skove, R. Ciocan, A.M. Rao, Electrical detection of oscillations in 340 microcantilevers and nanocantilevers, Rev. Sci. Instrum. 77 (2006) 073907]. The HDR technique exploits nonlinearities in the cantilever-counter electrode system to allow electrostatic actuation and detection of the responses of the microcantilever to the pressure and gas composition. In particular, the 2nd and 3rd harmonics of the measured charge on the cantilever are investigated. The microcantilever demonstrates a quality factor of 10,000 at 10−3 Torr, and a usable response in the range from 10−3 to 103 Torr. The use of different harmonics can enable us to adjust the range of pressures over which the sensor has an efficacious response, enhancing its sensitivity to a particular environment. The experimental results are in reasonable agreement with theoretical calculations, despite the nonlinearities involved. |
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Keywords: | Microcantilever Electrostatic Harmonic resonance Pressure Q-factor Gas environments |
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