When you think of hands-free devices, you might picture Alexa and other voice-activated home assistants, Bluetooth headsets, or asking Siri to make a phone call in your car. You might not imagine using your mouth to communicate with other devices, such as a computer or a phone remotely.
Thinking outside the box, MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and Aarhus University researchers have now built “MouthIO”, a dental brace that can be built with sensors and feedback components to record interactions and data in the mouth. This interactive wearable could eventually help dentists and other doctors collect health data and help people with mobility impairments interact with a phone, computer or fitness tracker using their mouths.
Looking like an electronic retainer, MouthIO is a clear brace that fits to the specifications of your upper or lower set of teeth from a scan. The researchers created a plugin for the Blender modeling software to help users adapt the device to fit a dental scan, where you can then 3D print your design in dental resin. This computer-aided design tool allows users to digitally customize a panel (called a PCB housing) on the side to integrate electronic components such as batteries, sensors (including probes for temperature and acceleration, as well as tongue touch sensors), and actuators ( such as vibration motors and LEDs for feedback). You can also place small electronics outside the PCB housing on individual prongs.
MouthIO: Building customizable oral user interfaces with built-in sensing and actuation
Video: MIT CSAIL
The active mouth
“The mouth is a really interesting place for an interactive wearable and can open up a lot of opportunities, but it has remained largely unexplored because of its complexity,” says senior author Michael Wessely, a former CSAIL postdoctoral fellow and senior author on paper for MouthIO who is now an assistant professor at Aarhus University. “This solid, liquid environment has complex geometries, making it difficult to create a portable interface for indoor placement. With MouthIO, however, we have developed a new kind of device that is comfortable, safe and almost invisible to others. Dentists and other doctors are excited about MouthIO for its potential to provide new health insights by tracking things like teeth grinding and potential bacteria in your saliva.”
Excitement for MouthIO’s potential in health monitoring stems from initial experiments. The team discovered that their device could monitor bruxism (the habit of teeth grinding) by incorporating an accelerometer inside the brace to track jaw movements. When attached to the bottom set of teeth, MouthIO detected when users grind and bite, with the data plotted to show how often users did each.
Wessely and his colleagues’ adaptive brace could one day also help users with mobility impairments. The team attached small touch pads to MouthIO, helping to detect when a user’s tongue hits their teeth. These interactions could be sent via Bluetooth to scroll a web page, for example, allowing the tongue to act as a “third hand” to open up a new avenue for hands-free interaction.
“MouthIO is a great example of how tiny electronics now allow us to integrate sense into a wide range of everyday interactions,” says study co-author Stefanie Mueller, TIBCO Associate Professor of Career Development in the Departments of Electrical Engineering and Computer Science and Mechanical Engineering of MIT. Engineer and Head of the HCI Engineering Group at CSAIL “I am extremely excited about the opportunity to help improve accessibility and monitor potential health issues among users.
Molding and manufacturing MouthIO
To get a 3D model of your teeth, you can first create a physical impression and fill it with plaster. You can then scan your mold with a mobile app like Polycam and upload it to Blender. Using the researchers’ add-on to this program, you can clean up the dental scan to outline an accurate brace design. Finally, you 3D print your digital creation in clear dental resin, where the electronic components can then be soldered. Users can create a standard brace that covers their teeth or choose an “open-bite” design in their Blender plugin. The latter fits more like an open-fingered glove, exposing the edges of your teeth, which helps users avoid bending and speaking naturally.
This do-it-yourself method costs about $15 to produce and takes two hours to 3D print. MouthIO can also be built with a more expensive, professional-grade dental scanner, similar to what dentists and orthodontists use, which is faster and less invasive.
Compared to its closed counterpart, which completely covers your teeth, researchers see the open bite design as a more comfortable option. The team preferred to use it for drink monitoring experiments, where they built a bracket capable of alerting users when a drink was too hot. This iteration of the MouthIO had a temperature sensor and display built into the PCB housing that vibrated when a drink exceeded 65 degrees Celsius (or 149 degrees Fahrenheit). This could help people with mouth numbness better understand what they are consuming.
In a user study, participants also preferred the open version of MouthIO. “We found that our device could be suitable for everyday use in the future,” says study lead author and Aarhus University PhD student Yijing Jiang. “Since the tongue can touch the front teeth in the open bite design, users have no lip. This made users more comfortable wearing the device during extended periods with breaks, similar to how people use retainers.”
The team’s initial findings show that MouthIO is a cost-effective, accessible and customizable interface, and the team is working on a longer-term study to further assess its viability. They are trying to improve its design, including experimenting with more flexible materials and placing it in other parts of the mouth, such as the cheek and palate. Among these ideas, researchers have already created two new designs for MouthIO: a single-sided mount for even more comfort when wearing MouthIO while also being completely invisible to others, and another fully capable of wireless charging and communication.
Jiang, Mueller and Wessely’s co-authors include PhD student Julia Kleinau, MSc student Till Max Eckroth and Associate Professor Eve Hoggan, from Aarhus University. Their work was supported by a grant from the Novo Nordisk Foundation and was presented at the ACM Symposium on Software and User Interface Technology.
