Researchers at Georgia Tech designed tiny metal disk tags that do not need batteries. The disks are smaller than a penny and cost only a few cents. They sit on a small 3D-printed base and attach to doors, drawers, faucets or other surfaces. A tab on the moving part strikes the disk when opened and the impact makes a short ultrasonic pulse people cannot hear. A nearby wearable device can detect and record the pulse.
The shape of each disk sets its resonant frequency, so every tag makes a unique sound fingerprint. Possible uses include counting repetitions in the gym, monitoring water use at faucets or toilet lids, and button-style tags to start a timer or log an action.
The team used a basic identification method that needs little computing, and ultrasound does not travel far so only nearby microphones detect a tag.
Difficult words
- attach — fasten or join one thing to another
- detect — notice or find something with a device
- resonant — vibrating in a strong, regular way
- ultrasonic — sound at a frequency humans cannot hear
- fingerprint — a unique pattern of a sound or signal
- impact — a strong hit or force when two things meet
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Where could you put one of these tags at home? Give one place.
- Would you use a tag to count exercises at the gym? Why or why not?
- What everyday action would you like a button-style tag to record?
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