The superior capacitive sensors can't go under your screen yet, and ultrasonic technology is still relatively new and expensive. Thus the optical scanner saw a resurgence in popularity.

To supply targeting data for the launcher, an Arduino Uno uses an ultrasonic sensor pair mounted atop a servo. As the servo rotates, the returns from the ultrasonic sensor are plotted on a screen ...

What this means is that the Vivo X Fold's fingerprint sensors could work like almost no other sensors out there. You will be able to use them even if your fingerprints are messy, like when your ...