'We came up with the idea that a person is warmer when they open their mouth. As long as there is heat there, the camera can pick it up. We are looking for a temperature change and motion when a person opens and closes his mouth.

'The mouth opening and closing just acts as a switch. That switch can be used to select letters of the alphabet from an on-screen keyboard or images in a picture communication board.

'That is how someone can use the one action (mouth opening/closing) to make choices. Now this individual is able to type on a computer using the thermal camera switch.''

In the lab, he said, the camera is pointed at the patient while he sits in front of the computer and every time he indicates a letter he wants, he opens his mouth and the camera captures it.

'A couple of weeks ago, the individual said his first word in his life, in his 26 years. This was in the lab and his mother was there. He was typing letter by letter (using his mouth as a switch). He typed m-u-t-h-e-r. His mom realized he was saying mother and she just broke down in tears. It was a dramatic moment. It has become such a liberating technology for this individual.''

The university statement says Chau and his team are the first in the world to use infrared thermography for this purpose.

(IANS correspondent Gurmukh Singh can be contacted at gurmukh.s@ians.in)