Tooth-mounted sensor capable of tracking food intake

By Will Chu

- Last updated on GMT

A miniaturised sensor mounted on a tooth. ©SilkLab, Tufts University.
A miniaturised sensor mounted on a tooth. ©SilkLab, Tufts University.
A miniaturised sensor that can be mounted on a tooth has been developed to transmit data on glucose and salt intake, in a development highlighting the progress made in health-monitoring wearable devices.

The sensor, developed by a team from Tufts University, is two millimetres (mm) by two mm that is able to bond to the irregular surface of the tooth.

“In theory we can modify the bioresponsive layer in these sensors to target other chemicals – we are really limited only by our creativity,”​ said Dr Fiorenzo Omenetto, corresponding author and the Frank C. Doble professor of engineering at 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.”

Upgrade in tech

The team believes the sensor’s abilities, coupled with its size, is an upgrade on previous wearable devices for monitoring dietary intake.

Similar technology suffered from limitations such as requiring the use of a mouth guard, bulky wiring, or regular replacement as the sensors rapidly degraded.

With this new sensor, a three-layered approach was taken, in which a central 'bioresponsive' layer absorbs the nutrient or other chemicals of interest.

The outer layers—made up of two square-shaped gold rings—complete a structure that is able to collect and transmit waves in the radiofrequency spectrum.

As the sensor registers an incoming wave, a portion of the signal is cancelled out. The remaining signal is transmitted back.

One other feature of the sensor is its ability to change its colour according to the nutrient or ingredient it absorbs.

Therefore, if the central layer were to absorb salt, its electrical properties will alter, triggering the sensor to absorb and transmit a different spectrum of radio frequency waves.

According to the team, the resultant variation in intensity is how nutrients and other analytes are detected and measured.

Sensor for nutrient and chemical range

“Such sensors can be easily multiplexed and yield data‐rich temporal information during the diffusion of analytes within the trilayer structure,” ​the study said.

“This format could be extended to a suite of interlayer materials for sensing devices of added use and specificity.”

News of Tufts University’s tooth sensor and the technology used illustrates how far innovation has come compared to previous efforts.

In 2013, the National Taiwan University developed a wearable oral sensory system​ that recognised when a person was chewing, drinking, speaking, and coughing.

The sensor, measuring—11-12 mm in size—could only be attached onto a separate artificial tooth.

Source: Advanced Materials

Published online ahead of print: DOI: 10.1002/adma.201703257

“Functional, RF-trilayer sensors for tooth-mounted, wireless monitoring of the oral cavity and food consumption”

Authors: Tseng P, Napier B, Garbarini L, Kaplan DL and Omenetto F.

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