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Abstract

An electronic fingerprint sensor works by the detection of pressure, the ridge lines of the finger exerting a greater pressure than the valleys. The sensor has a matrix of pressure microsensors and electronic control and signal-processing circuits. It is made in an entirely monolithic form, according to techniques for the making of electronic circuits (deposition of thin layers, photo-etching, doping and thermal processing), both for the pressure detection part and for the signal-processing and control part. The matrix-type pressure sensor uses either piezoelectric resistors lying on an insulator layer stretched above a cavity or a variable capacitor or a microcontactor.

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First Claim