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Open AccessArticle

Parametrically Amplified Low-Power MEMS Capacitive Humidity Sensor

Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT 84112, USA
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Sensors 2019, 19(18), 3954; https://doi.org/10.3390/s19183954
Received: 30 July 2019 / Revised: 9 September 2019 / Accepted: 11 September 2019 / Published: 13 September 2019
(This article belongs to the Special Issue Nano and MEMS Sensors)
We present the design, fabrication, and response of a polymer-based Laterally Amplified Chemo-Mechanical (LACM) humidity sensor based on mechanical leveraging and parametric amplification. The device consists of a sense cantilever asymmetrically patterned with a polymer and flanked by two stationary electrodes on the sides. When exposed to a humidity change, the polymer swells after absorbing the analyte and causes the central cantilever to bend laterally towards one side, causing a change in the measured capacitance. The device features an intrinsic gain due to parametric amplification resulting in an enhanced signal-to-noise ratio (SNR). Eleven-fold magnification in sensor response was observed via voltage biasing of the side electrodes without the use of conventional electronic amplifiers. The sensor showed a repeatable and recoverable capacitance change of 11% when exposed to a change in relative humidity from 25–85%. The dynamic characterization of the device also revealed a response time of ~1 s and demonstrated a competitive response with respect to a commercially available reference chip. View Full-Text
Keywords: humidity sensor; low-power sensors; MEMS; parametric amplification; spring softening humidity sensor; low-power sensors; MEMS; parametric amplification; spring softening
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MDPI and ACS Style

Likhite, R.; Banerjee, A.; Majumder, A.; Karkhanis, M.; Kim, H.; Mastrangelo, C.H. Parametrically Amplified Low-Power MEMS Capacitive Humidity Sensor. Sensors 2019, 19, 3954.

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