<title>CMOS-compatible micromachined tactile fingerprint sensor</title>

Abstract

We present in this paper a novel tactile fingerprint sensor composed by a single row of microbeams realized by the way of front side bulk micromachining from a standard CMOS circuit. When the user passes his finger on the sensor, the ridges and the valleys that compose the fingerprint induce deflections in the different microbeams. Using a piezoresistive gauge placed at their base, the deflections can be detected by means of a resistivity change. In addition of the MEMS part, this sensor includes in the same substrate the electronics control that allows to scan the row of microbeams and to amplify the signal from the gauges. A first prototype has been implemented and tested. This sensor dedicated to pixel tests includes three different rows composed by 38 microbeams that allow us to obtain a fingerprint image width of about 2 millimeters (spatial resolution of 50 micrometers i.e. 508 dpi).