This tiny tooth-mounted sensor to track what you eat

Scientists have developed a small tooth-mounted sensor that can wirelessly transmit information about glucose, salt and alcohol intake to a mobile device.

The future adaptations of these sensors could enable the detection and recording of a wide range of nutrients, chemicals and physiological states, according to researchers at Tufts University in the US.

Previous wearable devices for monitoring dietary intake suffered from limitations such as requiring the use of a mouth guard, bulky wiring, or necessitating frequent replacement as the sensors rapidly degraded.

The researchers sought a more adoptable technology and developed a sensor with a mere 2mm x 2mm footprint that can flexibly conform and bond to the irregular surface of a tooth.

The sensors transmit their data wirelessly in response to an incoming radiofrequency signal.

They are made up of three sandwiched layers: a central "bioresponsive" layer that absorbs the nutrient or other chemicals to be detected, and outer layers consisting of two square-shaped gold rings.

Together, the three layers act like a tiny antenna, collecting and transmitting waves in the radiofrequency spectrum, researchers said.

As an incoming wave hits the sensor, some of it is cancelled out and the rest transmitted back, just like a patch of blue paint absorbs redder wavelengths and reflects the blue back to our eyes.

The sensor, however, can change its "color."

For example, if the central layer takes on salt, or ethanol, its electrical properties will shift, causing the sensor to absorb and transmit a different spectrum of radiofrequency waves, with varying intensity.

That is how nutrients and other analytes can be detected and measured, researchers said.

"In theory we can modify the bioresponsive layer in these sensors to target other chemicals - we are really limited only by our creativity," said Fiorenzo Omenetto from Tufts.

"We have extended common RFID (radiofrequency ID)technology to a sensor package that can dynamically read and transmit information on its environment, whether it is affixed to a tooth, to skin, or any other surface," said Omenetto., corresponding author of the research to be published in the journal Advanced Materials.