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A Low Cost CMOS Compatible MEMS based Fingerprint Sensor Design

A. Ganesan1 S. Swaminathan1 N. N. Sharma2
1BITS, Pilani - Dubai, U.A.E.
2Mechanical Engineering Department, Birla Institute of Technology & Science, Pilani, Rajasthan, India

Stress variations in circular and rectangular beams.

In this paper, a novel design of a fingerprint sensor composed of a 2D array of piezo resistive micro beams has been presented. When the user presses the sensor array with a finger, the ridges and valleys that compose the fingerprint induce corresponding deflections in the micro beams. These deflections can be detected by means of a resistivity change, which when used with appropriate signal processing circuits, convert the deflections into an equivalent voltage signal. The design also includes post processing circuits comprising of A/D converter, needed to digitalize the amplified signal. The digitalized outputs from individual micro beams represent the pixels of the final fingerprint image. Stress variations of the piezoresistive sensor is as shown in the Figure 1

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