Ambient light powers shiny computer screens

Two very bright dots

A researcher at Napier University in Edinburgh has found a way to use ambient light to power a computer screen.

Janos Hajito made his discovery by mixing fluorescent dyes with polycarbonate, a transparent polymer. The resulting mixture was then stretched into fibres, which fluoresce at a particular frequency when struck by ambient light. This is reflected towards the end of the fibre.

Hajito told The New Scientist: "You're collecting light all the way along the fibre, so when it finally reaches the ends, you get two very bright dots."

By mixing different dyes, the colour of the fluorescence can be selected and hence a screen can be built up from loops of the fibres. By arranging the fibre ends in a grid, and covering it with a layer of liquid crystal that can block light from some fibres while allowing others to be seen, a proper screen can be built up.

Because liquid crystals are switched using change in voltage, rather than electrical current the screen works so efficiently it can even run at night, Hajito says.

He plans to use the technology to make bus shelter timetable displays, powered by the nearby street lights. ®

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