Engineering and computing researchers create simple metal tags with unique ultrasonic fingerprints to detect door openings and other movements.
Most smart home devices require power one way or another. You have to plug them in, recharge them, or replace their batteries at some point.
Georgia Tech researchers think they have a better way with small metal tags that can signal when a door or drawer is opened, count reps in the gym, or even track bathroom use for elderly relatives. Their tags are battery-free, quiet, inherently private, and cost only a few cents each. They’re smaller than a penny.
Like other kinds of smart home sensors, the tags are designed to be mounted on a cabinet or doorframe, for example, using a 3D-printed base. A small tab is attached to the corresponding door or drawer. When it’s opened, the tab strikes the metal disk, triggering a brief ultrasonic pulse imperceptible to human ears but detectable by a wearable device that logs the activity.