Steel-like material replaces silicon for tiny video projector

U.S. researchers have developed a more reliable way of developing microelectromechanical systems (MEMS), tiny machines that could make small video projectors on a chip.

For years engineers have used silicon as a material to create these machines, but researchers from Cornell University found that the material was easy to break, which made it too unreliable for systems that required flexibility.

So the researchers tested carbon fibre - the same material used to reinforce auto and aircraft body parts, bicycle frames, and fishing rods - to create a practical, though tiny, MEMS video display device.

The carbon fibre was able to bend past 90 degrees, and vibrate billions of times without breaking, which proved to be valuable for the scientists since the device needed a resonant frequency of 60,000 times a second - the line-scanning rate of most video displays.

Carbon is usually a brittle material, but when it is transformed into fibres, the Cornell group claims the material is stronger than steel.

Carry a projector in your pocket
The video display was made up of a tiny rectangular mirror measuring about 400 by 500 microns, and is supported by two carbon-fibre hinges.

It was made to oscillate at around 2.5 kHz, with the mirror generating a laser beam to scan across a range of up to 180 degrees.

When putting together an array of mirrors with the same functions, the scientists say this could produce an image the same way a moving electron beam creates an image on a television screen. Only it would be small enough to fit in a cellphone.

The study was published in the July issue of the Journal of Micromechanics and Microengineering.

Photography: MEMS Adaptive Optics

Source: Discovery Channel Reports, August 23 edition