Importance

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Abstract

A humidity sensor device which utilizes a humidity-sensitive piezoelectric polymer film as a transducer element. In a preferred embodiment a pair of excitation electrodes and a pair of pickup electrodes are provided on such a polymer film, a suitable excitation voltage is applied to the excitation electrodes and the resultant transverse piezoelectric effects are detected in the form of an electrical output voltage from the pickup electrodes. The electrical output signal is converted to the humidity value of the gaseous environment based on a prior calibration. Typically, an odd nylon such as nylon-11 or nylon-7 is used for the piezoelectric element and a rectangular, uniform and porous graphite films are deposited thereon as electrodes. The humidity sensor device of this invention can be used over a wide temperature range and can withstand repeated exposure to harsh temperature conditions over a long period of time.

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First Claim