Fingerprint Scanners

Go to a Best Buy, Target, or any store that sells smartphones. There’s a very good chance that the vast majority of the devices there have some sort of fingerprint reader – unless, of course, it’s name begins with “iPhone X”. Ever since the Pantech GI100 introduced the technology to the mobile world in 2004 and the iPhone 5s made it mainstream in 2013, fingerprint readers have done nothing but blow up, becoming a staple in smartphone design and functionality. We use them on a daily basis, but do we know how they work? Read on to find out…

The first prominent type of fingerprint scanner is the capacitive scanner, the most common(and most secure) form of fingerprint scanner found today. As the name would indicate, this type of scanner utilizes minuscule capacitor circuits that can measure changes in charge when a finger is placed on the scanner. Because these capacitors are so incredibly small, software and an op-amp integrator can be used to detect these changes and thus identify the unique fingerprint based on these attributes. Due to the electrical nature of this system, it is much more difficult to fool, owing to the fact that it requires an actual fingerprint rather than simply a visual impression of one. In addition, capacitive scanners are often more compact than others, hence why they can fit underneath relatively small home buttons on phones. However, the major downside of this type of scanner is that it is not compatible underneath a screen, so the hope of a bezel-less phone with one is completely and totally dashed.

Fear not, however! These next two types of fingerprint readers are what companies such as OnePlus, Samsung, and Vivo have been using lately to hide their biometrics under their phone screens, with the first of these being the optical scanner. Once, again, the name explains everything – in an optical scanner, a photograph is taken of your finger(if you’ve ever noticed, there’s a flash of light coming from where you put your finger – that’s a flash). Algorithms are then used to tell apart light and dark areas of the picture of your finger and all its ridges. This comes at a major disadvantage, however, for a simple picture or prosthetic of your finger is enough to fool it, and as such, aside from under-glass readers, optical scanners aren’t very popular.

The final(and certainly the least popular) form of fingerprint scanner that exists today is the ultrasonic scanner. A recent breakthrough headed by Qualcomm and the Samsung Galaxy S10, the ultrasonic scanner. This technology utilizes ultrasonic transmitters and receivers – a pulse is sent to your finger by the transmitter, and a highly detailed 3D map of your finger is created based on which parts of the ultrasonic wave are absorbed by the finger or reflected back to the receiver. While this technology isn’t quite as speedy as the capacitive scanners found in most phones today, the 3D nature of the map it creates of your finger enables it to be by far the most secure form of fingerprint reader, although it only works through a certain distance of glass – screen protectors are a no-go on this one.

It is important to note that a fingerprint reader’s speed and security is not just determined by its hardware – software also plays a massive role in it. The algorithms and cryptographical methods used by scanners and potential hackers alike will determine the true capabilities of fingerprint readers in the future. For now, however, it looks like this incredible convenient biometric lock will be with us for quite some time – just how much will these things improve over the coming years? Only time will tell…


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