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.

Gasboard-8500FS-X200 is Cubic’s ultrasonic technology 4-in-1 combined sensor solution to measure flow rate, oxygen concentration, temperature and humidity.

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 ...