Humidity sensor

Details Humidity sensor Humidity sensor

1990-08-01

1991-04-02

Chaudhuri, Olik

Fishing, trapping, and vermin destroying

437 40, 437228, 437231, 437235, 437 7, 357 25, 338 34, 338 35, 430311, H01L 21288, G01N 2712

Patent

active

050047000

ABSTRACT:
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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