Daily news

13 October 2004

A lighter approach to computer control

Fabrics woven from light-sensitive fibres could soon be embedded in computer and projector screens, making it possible to control computers by tracking the position of laser pointers, or other light sources, on the screen, researchers say.

Yoel Fink and colleagues from Massachusetts Institute of Technology in Cambridge, US, have borrowed techniques from the optical fibres industry to make long, light-sensitive threads.

The light-sensitive fibres can even respond to different colours of light

(Image: Greg Hren, Research Laboratory of Electronics, MIT)

The team started with a rod a few centimetres thick, consisting of a semiconductor core lined with metal wires, all contained within a polymer sheath. Then they heated the rod to over 300°C and drew it into a fibre hundreds of metres long and less than a millimetre wide.


The difficult part was persuading the different materials to stick together while the rod was stretched. “There were many messy disasters,” Fink says, but once the team found materials that melted at the same temperature and flowed in the same way, “it worked beautifully”.

Existing processes for making fibres containing polymers, semiconductors and metals are far more complex, with the different materials being incorporated in separate steps.

Dislodging charges

The fibres made by Fink’s team respond to light because photons hitting the semiconductor core dislodge electric charges, affecting the voltage in the fibre’s metal wires. Current changes in a grid of such fibres can then pinpoint exactly where a light source is striking the surface.

Embedding these grids in computer screens could provide a new type of interface, says Fink. “Instead of having mechanical mouse, you could just take light beam and communicate with the computer because the screen would know where it was being hit,” he told New Scientist.

The fibres can be tailored to respond to a particular colour of light by leaving a gap between the semiconductor layer and polymer coating. This acts as a filter, letting through only one wavelength of light. A side effect is that such fibres are themselves rainbow-coloured (see image).

The team has woven the fibres into a fabric about 30 centimetres square but believe that much bigger light-sensing structures should be possible. They also think they can build transistors into the fibre structures to give them computational power.

“This has a pretty exciting future ahead of it,” says Fink. The group have applied for patents and “we will be engaging interested parties in trying to get it licensed”.

Journal reference: Nature (vol 431, p 826)