  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). 11-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 ~1s and demonstrated a competitive response with respect to a
commercially available reference chip.
