Disabled scientist Professor Stephen Hawking is using a hi-tech gadget to communicate by blinking because his deteriorating health limits movement.
Professor Hawking delivers lectures at Cambridge University
The 63-year-old physicist is Britain's longest surviving sufferer of the debilitating Motor Neurone disease.
He uses one hand to control the computer which gives him a voice.
But his hand is getting weaker and he is now using a new gadget, which allows him to control the computer simply by blinking his eye.
David Pond, Professor Hawking's graduate assistant at Cambridge University, said: "His hand has been slowing down."
He added: "He wants to fight all the way but he recognises he needs a better way to communicate.
"He started using the switch two months ago. It's very simple to use and it's going really well."
The Infrared Sound Touch (IST) switch has been developed by the American company Words+ and works by emitting a very low-powered infrared beam.
The reflection of the beam changes when the eye is closed and the cheek muscle moves and so controlling the computer is as simple as blinking.
It is attached to Professor Hawking's glasses an inch from his cheek to detect the moving muscle.
Professor Hawking achieved international prominence with the publication of his book A Brief History of Time in the late 1980s.
He developed motor neurone disease while studying at Cambridge University in his early twenties.