Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.

Redmi, a Xiaomi spin-off phone brand, says it has made in-display fingerprint sensors that work with LCD screens. Previously, only OLED screens supported them.

Over the past few years we've seen one quite significant difference between Android phones and the iPhone: biometric authentication methods. While iPhones - since the iPhone X - have all used advanced ...