How Fingerprint Scanning Works: Capacitive Scanning
Unlike optical scanning which generates an image of a person's fingerprint by using light, capacitive scanners use electrical currents to achieve that. The sensor used in this scanning technology is made up of one or more semiconductor chips which is connected to an inverting operational amplifier; each chip is made up of two conductor plates. This very complicated device cleverly reads each fingerprint by measuring the different electrical voltage given by the ridges and valleys of each finger. The processor embedded into the scanner then reads the voltage output and puts together a picture of the scanned finger. From there it decides whether or not it matches up with authorized prints in the database.
Capacitive scanners have two advantages over optical scanning: 1) It requires an actual image of a fingerprint in order wot work properly and cannot be tricked by simply manipulating patterns of lights that make up the impression of a fingerprint. 2) Due to the size of semiconductor chips, capacitive scanners tend to be smaller than its optical counterpart.
by FingerTec USA