Whether eating, drinking, talking, coughing, breathing or smoking, our mouths are always in use. Because the mouth is an opening that can yield health information for our body, a team from National Taiwan University created a sensor that embeds within a single tooth.
The sensor is so small that it can either fit inside an artificial tooth or straddle a real one.
Using an accelerometer to monitor different activities of the mouth, the team used tiny wires within the sensor to carry data to a computer, though they say that future models of the sensor will use Bluetooth for wireless reporting.
They presented their device in early September at the International Symposium on Wearable Computers in Switzerland.
Motivation for creating the device, say the researchers, was based on the idea that most oral activities "produce a unique teeth motion." They note that since the sensor is able to measure jaw movement, it can build "classifiers" that categorize different activities of the mouth.
(a) The sensor fits in between teeth
(b) The tri-axial accelerometer
(c) Sensor implanted in a set of dentures
Credit: Cheng-Yuan Li et al.
In order to test the accuracy of the sensor, the team had eight volunteers wear the sensor while performing different activities, such as coughing, chewing gum and talking, while the computer analyzed the data and built a personal profile for their oral activities.
Then, the volunteers were asked to repeat the activities while the sensor distinguished each one from another. In total, the team collected 480 activity samples from the participants.
The researchers say that the tooth sensor was 93.8% accurate in recognizing oral activity when it was using a "person-dependent classifier," which is the profile created for each specific person.
Although the accuracy went down to 59.8% when the sensory system was using a "person-independent classifier" (meaning the system was not using a tailor-made profile for each person), the researchers note that this may be due to differences in how people perform oral activities.
For example, they note that "some people chew or talk faster, slower, harder or softer." They say it will be possible to improve this accuracy by "extending the training set to include different sensor placements and oral activity types."
Tooth sensor for health monitoring
The team says the information collected by the sensor could be very helpful to dentists, doctors and other scientists, since the device can provide information on teeth grinding, eating or drinking levels, and it could even measure stress levels.
Because the sensor is placed inside the mouth, the researchers say that safety is, of course, very important. They note all electronic parts have to be sealed and if the sensor is swallowed, it will pass through the body without causing harm.
"Its safety requirements are similar to those of capsule endoscopy, in which patients swallow a camera pill," they say.
Continuing work to improve the sensor is the team's current focus, and they expect to have a wireless sensor available soon that will fit inside a normal crown.
Once this development has been completed, they say it would mean that tooth sensors could one day become standard procedure in dental and health offices for health monitoring.