How does fingerprint scanner work? Types of fingerprint scanners

 How does Fingerprint scanner work?

Smartphones with fingerprint scanners under the display are finally here. It is the next big thing in the smartphone market. And it looks and feels futuristic. But how does it compare to the common capacitive fingerprint scanner.

Let's find out...

Human fingerprints are actually very unique and no two people will have the same fingerprint. Even identical twins will have slightly different fingerprints. So having a fingerprint lock to protect the personal information on our phone is a really

good idea. Fingerprint scanners work by capturing the pattern of ridges and valleys on your finger. The information is then processed by the phone's pattern analysis and matching software, which then compares it to the list of already registered fingerprints on the phone.

And if a successful match is found, your identity will be verified, and access will be granted to unlock the phone.

Types of fingerprint scanner?

There are actually 3 different types of fingerprint scanners commonly used in phones

The Optical Fingerprint Scanner

As the name suggests, the optical fingerprint scanner uses a light source, usually an LED, to illuminate the finger. The reflected light is then captured by a light-sensitive microchip to create a digital image of your fingerprint. So basically, these scanners just make a photocopy of your finger. The major drawback is that it can easily be fooled with just a high resolution photograph of your fingerprint. Also, it is bulky. So most modern smartphones don't use the optical sensor. It was first used in Pantech Gi 100 which was launched way back in 2004 but since then it was slowly phased out. Optical Indisplay Fingerprint Scanner

Synaptics recently introduced a new type of optical indisplay finger scanner at CES 2018.
It is now being used in a bunch of Chinese smartphones. It is much smaller but works exactly like the normal optical sensor. The only difference is, the sensor is actually placed under the display and the display itself acts as the light source to illuminate the finger. This is why we see those cool light animations when the phone is unlocked. The main advantage of this fingerprint scanner is that it can be placed anywhere under the screen or if required the whole screen can be used as a fingerprint scanner and also it works well even with wet fingers But it has a few major flaws though It works only with OLED screens and doesn't work with LCDs. This is because LCD screens don't allow light to pass through them. But for the optical scanner to work, light has to actually pass through the screen and reach the fingerprint scanner placed below it. Another potential issue is that this scanner doesn’t work well with screen protectors. So you might have trouble finding one that’ll work. Also, if the display is damaged it would cost more to repair since the scanner is now integrated with the display.

Capacitive Fingerprint Scanner

The Capacitive fingerprint scanners are the most commonly used fingerprint scanners in recent smartphones. These scanners take advantage of the fact that human skin is a good conductor of electricity. The scanner is actually made up of an array of capacitors. When we touch the scanner, the capacitors are charged. But this happens only at the ridges while the capacitors below the valleys remain uncharged. This difference in capacitance between ridges and valleys is then captured by the sensor

to form the digital image of the fingerprint The advantages of capacitive fingerprint scanner over optical ones is that it can not be easily fooled using just a photograph of the fingerprint. Also it is faster and more accurate. But the capacitive scanner also has a few problems. It requires a clean finger to work properly, as something like dust or sweat can affect the conductivity of the finger. Also, it is costlier And doesn't work when placed under the screen It is also not completely foolproof and can be fooled by using a mould of our finger

The Ultrasonic Fingerprint Scanner

The Ultrasonic scanners are the newest entry in in-display fingerprint scanning technology. It uses ultrasound to scan and capture the 3D fingerprint data similar to how bats and dolphins use echolocation to find and identify objects. This generates a highly detailed surface map of the fingerprint which is extremely difficult to imitate or spoof. There is virtually no limitation to where the scanner can be placed inside a smartphone. As it can work even when placed under the glass screen, metals or even plastics. It also works well with common contaminants like sweat, dust and hand lotion to create a more accurate scan than capacitive scanners

The ultrasonic scanner is currently only in prototype stage and is being tested by Qualcomm for use in mobile devices. Also it is rumoured to be featured in the upcoming Samsung Galaxy S10 or the Note 10 But here is the thing, the under display fingerprint technology isn't quite there yet. It is not as consistent as a normal capacitive scanner and is also considerably slower. But, it is a relatively new technology and as more companies start to implement this tech, it will be perfected in the next couple of years. Or maybe sooner…

Which fingerprint scanner do you like the most?

Comment below.