The latest prototype of the 'Tongue Drive' allows wireless wheelchair direction by movement in the mouth for those with severe spinal cord injuries.
The new system was presented yesterday at the IEEE International Solid-State Circuits Conference in San Francisco. Its development is supported by the National Institutes of Health, National Science Foundation, and the Christopher and Dana Reeve Foundation.
For those with limited movement capabilities, the wireless device allows the operation of an electrically powered wheelchair through the 'drive' which is inserted into the mouth via a retainer. It can also be used to direct computer systems, such as a cursor on a screen.
The retainer sits against the roof of a user's mouth and is molded inside dental acrylic as well as being covered in water-resistant material. The sensors within the retainer track the movement of a magnet attached to the tongue, which then relay movements to an electronic device.
The output signals generated by the sensors are transmitted to an iPod or iPhone, where specialist software interprets the information in real-time to control cursors on a computer screen or replace more traditional control functions on a wheelchair.
The dental model includes a rechargeable lithium-iron battery and an induction coil to allow charging.
Developed at Georgia Tech, the circuitry embedded within the retainer interprets a range of different tongue movements. After completing a number of clinical trials that found the technology could be used successfully, Maysam Ghovanloo, an assistant professor in the School of Electrical and Computer Engineering at the Georgia Institute of Technology said:
"Trial participants were able to easily remember and correctly issue tongue commands to play computer games and drive a powered wheelchair around an obstacle course with very little prior training."
The latest prototype's update included the design of the new retainer -- rather than a previous model which required the user to wear a headset. Instead of a magnet placed on the tongue and its movement linked to this kind of headwear, now, the sensors required are embedded inconspicuously -- which is more stable, durable and more comfortable according to the team.
"One of the problems we encountered with the earlier headset was that it could shift on a user's head and the system would need to be recalibrated," said Ghovanloo. "Because the dental appliance is worn inside the mouth and molded from dental impressions to fit tightly around an individual's teeth with clasps, it is protected from these types of disturbances."
The researchers hope to begin more extensive clinical trials of the technology soon.
Image credit: Georgia Tech