How does fingerprint sensor work? A Blog by Ayush Yadav

There are plenty of sensors present in our smartphone and fingerprint sensor is one of the most prominent sensors in them.

The password formed by the combination of letter and word can be guessed with the knowledge of computer programming or by hit and trial method. So there was a need of much stronger security, hence fingerprint sensor came into the picture.

There are three different kinds of pattern namely Arch, Loop and Whorl which make each fingerprint unique. Fingerprint sensor analyzes them for better security and blocks unauthorized access. The optical fingerprint sensor and Capacitive fingerprint sensor are two major classifications of the fingerprint sensor.

As one taps his finger from the different angle while registering a fingerprint for the hardware, Optical fingerprint sensor takes a snap of the finger from a different angle and prepare a map removing a common area. This map is stored in the memory and whenever a user tries to open the device with his fingerprint, optical fingerprint sensor makes sure that it is matched with the previous map present in memory. On matching it grant access to use otherwise denied. The map is prepared by taking care of key information of fingers like ridges bifurcation, smaller ridges and ridges end. It also takes valley i.e. the gap between two ridges in an account to prepare the map.

Another kind of fingerprint sensor, i.e. capacitive fingerprint sensor makes use of capacitors of very small size which is placed on the fingerprint sensor. When a user presses his finger on the sensor while registering, ridges area gets activated and capacitor present in the valley region doesn’t get activated, and thereafter it prepares a map for the same which is recalled and matched when a user tries to unlock hardware with his fingerprint.

As optical fingerprint sensor takes a snap of the finger from different angles, so it can be fooled by presenting a copy of fingerprint in front of it, whereas capacitance fingerprint sensor makes use of capacitors and works on ON-OFF concepts so it can’t be fooled easily. Normally the acceptance rate is 90% for a capacitive sensor which makes sure that no unauthorized person accesses the account and hence take an edge over an optical sensor in terms of response and security.

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