Sharp Kabushiki Kaisha Corporation

Emi, LLC

Derek G Pedley

Masaya Hijikigawa

Hisatoshi Furubayashi

Brian C Webb

Stephen J Prosser

A method of making a humidity sensor comprises providing a host device constituted by a semi-conductor substrate (10) and a gate insulator (13) of an insulated gate field effect transistor, forming a layer (14) of poly (vinyl) alcohol (PVA) on the exposed surface of the insulator, heat treating the layer to crystallize and stabilize the PVA, and forming a gate electrode (15) on the PVA layer, so that the gate electrode is porous allowing ambient water vapor to be absorbed by the PVA which, in response, undergoes a change of bulk dielectric constant, thereby causing a change in gate capacitance of the transistor resulting in a detectable change of electrical conductivity in the drain source channel.

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Amersham, United Kingdom

Derek G Pedley