Steering with a slip of the tongue
Tongue twisters can control next-generation wheelchairs, neural engineer, Ravi Vaidyanathan tells Reshma Patil.
How the tongue moves can move a wheelchair...really?
An earplug with a very small microphone can record changes of airflow in the ear, like sound waves. When you move your tongue, the resulting waves within the mouth propagate through bone, tissue, and air into your ear canal.
The movements are easy, like speaking. Try touching the tongue to the bottom centre of your mouth and very gently flick it upwards. For almost everyone, this creates a very clear signal. So moving your tongue to the right or left could tell the chair to go right, left.
How is your design an improvement over current wheelchairs for quadriplegics?
For those who cannot move arms easily, joysticks are not an option. Some devices control by blinking or head movements, but need extra equipment, are uncomfortable, and force one to constantly be aware of these movements.
Some devices do use the tongue or lips to control a wheelchair, but one has to pull out the saliva-soaked device every time the users want to speak or eat. With hygiene and discomfort issues, the device cannot be left in the mouth for long.
Our system is the first method of tracking tongue movement without requiring anything placed in the oral cavity. It is comfortable and does not impede talking, eating. It reduces the need for a caregiver and avoids muscle fatigue, repetitive motion injury, and skin abrasion.
What triggered the idea?
It came from considering that when one thinks, concentrates, or moves, there are reactions that create signals that can be recorded. If you concentrate with a level of intensity, for example, your heart rate, breathing, electrical and acoustic signatures all change — sensors can record, and possibly recognise this.
The idea of recording signals out of the ear came from a colleague (formerly with the US-based Think-A-Move) with whom I started work in 2001. I applied to the US National Institutes of Health for support and teamed with Professor Lalit Gupta at Southern Illinois University to develop the system.
Will the wheelchair be available globally?
Hopefully, yes, in the near future. Industry will decide the price, but the earpiece and microphone are inexpensive.
Will you tweak the design for other applications?
Absolutely, as a household aid for the disabled to turn lights on/off, change TV channels, use a mouse. And a soldier or firefighter could direct a robot by tongue, to search for explosives or trapped people, while his hands are occupied.
Are you part of the diaspora?
My parents moved from Tamil Nadu to the US in 1970, before I was born. I lived most of my life in the US, but really enjoy spending time in India. I'm currently a lecturer in neural engineering at the University of Southampton, UK.