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.

Qualcomm has partnered with Katouzian to announce the world's first 3D ultrasonic in-display fingerprint sensor for mobile devices. Here's what you need to know!

Google has just launched the new Pixel 9 series and the core series includes an upgraded ultrasonic fingerprint sensor.