Our fingerprints function as biometric identity cards with which we are born (as no two prints are alike). For this reason, not only are fingerprints crucial when it comes to solving crimes, but they have also made fingerprint scanning a widespread security system. Over the past years, fingerprint recognition technology has become a standard smartphone feature, included in every flagship phone, in almost all mid-range models, as well as in budget smartphones.
When it comes to consumer electronics, fingerprint scanners are generally used to unlock devices, provide secure folder access, and authorize transactions. Fingerprint recognition systems are either stagnant or moving: the first type requires the user to drag their finger over the scanning area, whereas the second (and most reliable) form has a scanner that moves across the area. As for scanning technology, the most popular methods are optical scanning, capacitative scanning (or CMOS scanning), ultrasonic scanning, and thermal scanning.
The oldest method of fingerprint recognition, optical scanning works with a digital camera that photographs the fingerprint, and with algorithms that detect distinctive features (like ridges and patterns). This method is flawed by low scan resolution and 2D-imaging, which makes it relatively easy to dupe. Currently, the most popular fingerprint scanners are capacitive systems, which utilize electrical current to trace the details of a fingerprint (although a finger mold may still fool it). Another advanced fingerprint recognition tech is ultrasonic scanning. Still quite expensive, ultrasonic fingerprint readers employ high-frequency waves that penetrate the skin and read fingerprint information underneath the epidermis. Finally, thermal scanners operate by detecting temperature variation between a fingerprint's unique ridges and valleys and generating a high-quality grayscale image.
A growing number of smartphone manufacturers are utilizing in-display fingerprint scanners, allowing for gorgeous edge-to-edge displays. The first smartphone to incorporate an in-display fingerprint scanner was the Vivo X20 Plus UD, released in 2018. Since then, in-display fingerprint scanners have become more common and can even be found on mid-range phones such as the Samsung Galaxy A31. It’s worth noting, however, that the majority of phones with in-display readers use optical scanning technology. The superior ultrasonic fingerprint scanners are currently only found on high-end Samsung phones, such as the Samsung Galaxy S21 5G. With security being a mounting concern, fingerprint scanners are also in high demand for other devices such as tablets and laptops.