A capacitive scanner is a fingerscanning device that uses an array of capacitive proximity sensors, along with a microcomputer and associated electronic signal processing circuits, to create and store a digital image of a human fingerprint.
Instead of photographing an image of the ridges and valleys in a fingerprint as an optical scanner does, a capacitive fingerscanner's sensors generate a complex pattern of electrical currents, which are processed to form a digital image of the fingerprint. Because the capacitive scanner requires the physical presence of the human finger in order to generate the image, it is more difficult to fool than an optical device, which can sometimes render an apparently legitimate file from a high-quality photograph.
Fingerscanning, also called fingerprint scanning, refers to any of several different technologies for electronically obtaining and storing human fingerprints. The digital image obtained by such scanning is called a finger image. Other methods of fingerscanning besides the capacitive method include optical scanning, thermal (heat) sensing, and pressure sensing.