This tooth-mounted sensor will tell you more about what you eat

Human teeth are among the most extraordinary feats of nature—and now, they may even be able to track what you ate and help you monitor your dietary intake.

Researchers at the Tufts University School of Engineering have developed a tooth-mounted sensor that can wirelessly transmit data on the intake of elements such as glucose, salt and alcohol. The sensor, which can be placed on the tooth, sends the information to a mobile device.

The sensor has been designed in a way that it can adapt to the tooth’s uneven surface. According to a news release on the university’s website, the sensor is made up of “three sandwiched layers". There’s “a central ‘bioresponsive’ layer that absorbs the nutrient or other chemicals that can 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 radio frequency (RF) spectrum". These waves can then be detected and recorded using radio-frequency identification (RFID) devices.

For the outer layers, the researchers used two stacked split-ring resonators, which are commonly used in meta-materials (made using different elements so that they exhibit different properties, such as electric and magnetic resonance, that are not found in natural or conventional materials), to produce magnetic responses. According to the research paper, published in the journal Advanced Materials earlier this year, the resonators’ small form factor and “lower resonant frequency" make them apt for use with traditional RF instruments.

To test the effectiveness of the central “bioresponsive" layer, the sensor was exposed to solutions like deionized water, artificial saliva, ethanol, methanol and saliva samples that had high levels of salinity. The news release explains: “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 radio-frequency waves, with varying intensity. That is how nutrients and other analytes can be detected and measured."

While the sensors might be restricted in terms of the elements they can analyse right now, all that could change in the future. “In theory, we can modify the bioresponsive layer in these sensors to target other chemicals…," noted Fiorenzo Omenetto, the corresponding author and the Frank C. Doble professor of engineering at Tufts.

Other authors on the paper were Peter Tseng, a postdoctoral associate in Omenetto’s laboratory; Bradley Napier, a graduate student in the department of biomedical engineering at Tufts; Logan Garbarini, an undergraduate student at the Tufts School of Engineering; and David Kaplan, the Stern Family professor of engineering, chair of the department of biomedical engineering, and director of the Bioengineering and Biotechnology Center at Tufts.

The sensor—a square-shaped object not bigger than 2x2mm—is not the first of its kind. In 2013, researchers at National Taiwan University had come up with a prototype of a smart tooth sensor that was designed to recognize human oral activity such as chewing, drinking, speaking and coughing.

The only possible drawback was that this prototype was connected to thin wires that were used to connect the sensor board to an external data-logging device. These thin wires were also designed to protect users from swallowing the sensor units. According to the official research paper, “in actual system deployment (or in the future), this sensor board would include a small Bluetooth radio capable of wirelessly transmitting sensor data to a nearby mobile phone for data analysis and oral activity recognition".

“At the moment, the sensor is attached to the outside world by a thin wire. This carries electricity in and data out, but it is inconvenient to have to walk around all day with a wire sticking out of your mouth," a 2013 article in The Economist commented, about this prototype.

This is one area where Tufts University’s research stands out from previous prototypes. Too much salt or too much sugar? In the future, your teeth could ensure you eat well—and right.