Sensor knows when you're lying through your teeth

A sensor embedded in a tooth could one day tell doctors when people have defied medical advice to give up smoking or eat less. Built into a tiny circuit board that fits in a tooth cavity, the sensor includes an accelerometer that sends data on mouth motion to a smartphone.

Machine learning software is taught to recognise each telltale jaw motion pattern, then works out how much of the time the patient is chewing, drinking, speaking, coughing or smoking.

The inventors – Hao-hua Chu and colleagues at National Taiwan University in Taipei – want to use the mouth as a window on a variety of health issues. The device can be fitted into dentures or a dental brace, and the team plan to miniaturise the device to fit in a cavity or crown.

The researchers say the sensor shows great promise: in tests on eight people with a prototype implant installed in their dentures, the system recognised oral activities correctly 94 per cent of the time.

The prototype was attached to a power source by an external wire, so the team still needs a way to include a microbattery.

Once they manage this, the researchers want to add a Bluetooth radio to the device. But as that is a microwave energy source – albeit a very low power one – Chu says medical experts are advising the team on how to ensure the implant would be safe.

If miniaturised and made wireless, the device has potential, says Trevor Johnson, vice-chair of research at the Faculty of General Dental Practice in the UK. "This could have a number of uses in dentistry, for example as a research tool, for monitoring patients who clench or grind their teeth, and for assessing the impact of various dental interventions," he says.