How does a fingerprint scanner work on a smartphone

How does a fingerprint scanner work on a smartphone

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In smartphone it recognizes patterns from the highs and lows from your finger. Each finger has a unique patter. Now how it does this in depth depends on which type of fingerprint scanner the phone uses. There are 3 basic types of fingerprint scanners that is Optical fingerprint scanner, Capacitive fingerprint scanner, Ultrasonic fingerprint scanner.

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Optical fingerprint scanner:

Optical fingerprint scanners are the oldest method of capturing and comparing fingerprints. These type of scanners have a source light, which emits laser light to a prism. The prism is placed in such an angle to this light that due to total internal reflection, the light emitting from the source touches a side of the prism and reflects back. This reflected light is then captured by a sensor. This captured light is then converted into a digital image and used for validation. When you place your finger on the sensor, you block the total internal reflection from the source, thereby helping the sensor to take a high resolution picture of your finger. This type of scanners really isn’t secure enough to trust your most sensitive details to. It’s also slowly being phased out these days.

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Capacitive fingerprint scanner: 

You’ll find these type of scanner inside various flagships, including the Galaxy S8, HTC U11, LG G6, and others. These type of scanners discard the source light and the prism. They directly use the sensor and charge coupled device under metallic plate. They receive charges from your finger. The ridges of your finger conduct electricity and valleys don’t. This creates a charge pattern in the CCD, which can be used for validation. In future, many more devices may support a wider variety of swipe and navigation features using their fingerprint scanners.

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Ultrasonic fingerprint scanner: 

The latest fingerprint scanning technology to enter the smartphone space is an ultrasonic sensor, These sensors emit ultrasonic waves from a source which can travel through glass, metal, etc. but gets reflected by your finger. These reflected waves are captured back by its receiver and a 3D model of your fingerprint is created for validation. An ultrasonic pulse is transmitted against the finger that is placed over the scanner. Some of this pulse is absorbed and some of it is bounced back to the sensor, depending upon the ridges, pores and other details that are unique to each fingerprint.