The Fingerprint Sensor Of Your Phone

Phones use one of three different technologies to read your fingerprint: optical, capacitive or ultrasonic. An optical fingerprint reader is the oldest of the three. It uses a specialised miniature camera to take a picture of your finger, often backlit with little LEDs or the phone’s screen.

Unfortunately, these sensors are easy to fool – even a good photo can trick them, so it may be combined with a capacitive sensor, the second technology, to check there is really a finger there.