September 1, 2008
(click to enlarge) Maysam Ghovanloo developed the tongue-drive system to enable victims of spinal cord injuries to live more independently.
Most people don't give a second thought to how their tongue moves. But the powerful muscle can go beyond speech. One professor at the Georgia Institute of Technology (Atlanta) is capitalizing on this idea with a device that helps those with disabilities control their wheelchair with the simple movement of the tongue.
The tongue-drive system, developed by Maysam Ghovanloo, is designed for people who have brain function, but have lost the connection between their brain and the rest of their body. Victims of spinal cord injuries sometimes have this condition. The goal of the device is to enable users to live more independently.
Other technologies that aim to help patients include brain–computer interfacing and eye trackers. Brain–computer interfacing records and analyzes the brain's electrical activities to determine the person's intentions, such as driving a wheelchair. But the process is invasive, because the electrodes must be implanted.
Eye tracking places a camera in front of the user's face. Image-processing software focuses on eye movements, but the system can interfere with vision. A tongue-touch keypad for communication and navigation has also been on the market, however it requires a tiring application of tongue pressure.
Ghovanloo, an assistant professor at Georgia Tech's School of Electrical and Computer Engineering, says the tongue-drive system solves these problems. It is noninvasive and based on tongue movements, not pressure. A magnet placed inside the mouth works with external sensors and wirelessly transmits signals to a portable computer. The sensors control the motion of a cursor on the computer screen and can function similarly to a joystick when powering a wheelchair.
Users can talk while driving their wheelchair or accessing their computer. The researchers have differentiated the types of commands associated with tongue movements versus those made during speech, so there's no interference. The system can be trained to execute commands based on unique tongue movements. It also goes into standby mode when the user is eating or sleeping.
The only object inside the mouth is a tiny magnet. Depending on whether the user wants the device temporarily or permanently, the magnet can be placed on, implanted in, or pierced through the tongue. “When they're testing it in our lab, I haven't been able to convince my students to get a tongue piercing,” says Ghovanloo. “We add a little bit of tissue adhesive onto the top of the small magnet and place it on the surface of the tongue. It attaches to the tongue for a few hours, and then it comes off.”
A magnet placed inside the mouth relays tongue movements to an external sensor, which transmits signals to a portable computer.
To use the system permanently, the patient's tongue would be pierced, and the magnet would replace the jewelry normally found atop the piercing. Another option is tongue implantation, which Ghovanloo has not yet attempted. In that case, a magnet would be inserted under the tongue with a hypodermic needle.
Two magnetic sensors are located outside the mouth. Ghovanloo envisions a headset-style device that has magnetic sensors on the tip.
“Even though this prototype is fine for getting the job done, from the aesthetic point of view it could look much nicer,” says Ghovanloo. “Eventually we would like the headset to look like a nice headphone. We're working on a very fashionable headset to be designed by a professional industrial designer.”
The device's function has been demonstrated, and researchers are working on providing the user with proportional control as opposed to the current switch-based system. Proportional control works like a joystick, making turning and adjusting wheelchair speed easier. The further forward the joystick is pushed, the faster the system moves. The switch-based system involves pressing keys to drive the wheelchair.
They also plan to add commands and simplify the graphic user interface. “One advantage of this system is that you can associate any arbitrary tongue movement to a particular command,” says Ghovanloo. “If you move it forward, left, and down, that [combination] could be a command.”
Ghovanloo says there's room for improvement. The researchers have already conducted three rounds of trials with student volunteers who had no disabilities. Their next goal is to get feedback from people with disabilities.
An internal version of the tongue-drive system has also been designed in the form of an orthodontic brace. The entire system is placed inside the mouth on the outer surface of the teeth. It will have a rechargeable battery and a much smaller area of sensors. Ghovanloo anticipates a functional and more-attractive version to be ready in about 12–18 months.
Ghovanloo has been working on the patent-pending system with Georgia Tech graduate student Xueliang Huo. Their research is being funded by the National Science Foundation, and the Christopher and Dana Reeve Foundation.
Copyright ©2008 Medical Device & Diagnostic Industry
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