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.

Strictly speaking, a Theremin uses a pair of antennae that act as capacitors in a specific R/C circuit. Looking at ...

A new ultrasonic fingerprint sensor measures 3-D image of your finger's surface and the tissue beneath it -- enhancing biometrics and information security for smartphones and other devices ...

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