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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
Author to whom correspondence should be addressed.
Sensors 2019, 19(18), 3954;
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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