Cornell University researchers are replacing silicon components in microelectromechanical systems (MEMS) with carbon fibre, which is stronger and more flexible and could be used in video devices.
For decades, researchers have been trying to make video displays using tiny mirrors mounted on silicon oscillators, but silicon cannot oscillate fast enough or bend far enough.
Shahyaan Desai, a Cornell graduate student who has been to create a practical MEMS video display device, decided to try carbon fibre, which is twice as stiff as silicon but 10 times more flexible.
Desai first showed that micrometre-scale carbon fibres can bend like tiny fishing rods by more than 90 degrees and can be made to vibrate billions of times without breaking down.
He then built an optical scanner consisting of a tiny rectangular mirror measuring 400 by 500 microns, supported by two carbon-fibre hinges about 55 microns across. Made to oscillate at 2.5kHz, the tiny mirror caused a laser beam to scan across a range of up to 180 degrees, corresponding to a 90-degree bend by the carbon fibres.
An oscillating mirror could be used to scan a laser beam across a screen, and an array of mirrors, one for each horizontal line, could produce an image in the same way that a moving electron beam creates an image on a television screen.
‘It would be an incredibly cheap display,’ Desai said. The entire device would also be small enough to build into a cell phone to project an image on a wall.