Currently, semiconductor chips comprise minuscule electronic transistors on beds of silicon. Such devices cannot be made much smaller because of how matter behaves at the quantum scale they're approaching. Eager to overcome this, engineers are now looking at new ways and materials to perform logic and memory functions.
The device, developed by a team from the University of Tokyo, is different from current semiconductor chips as it is chemical in nature, and it's this property that gives rise to its potential usefulness in the future of computation. The device could be manufactured cheaply and easily too, the researchers add.
The device features disk and rod-shaped molecules that self-assemble into spiral staircase-like shapes called columnar liquid crystals (CLC) in the right conditions.
Before a logic operation begins, the researchers sandwich a sample of CLCs between two glass plates covered in electrodes. Light that is polarised passes through the sample to a detector on the other side.
In the sample's default state, the CLCs exist in a randomly oriented state which allows the light to reach the detector. When either the electric field or UV light is individually switched on then off, the detected output remains the same. But when the electric field and UV light are switched on together and then off again after about a second, the CLCs line up in a way which blocks the detector from the light.
If the "output" states of light and dark, and the "input" states of the electric field and UV light are all assigned binary digits to identify them, then the process has effectively performed what is called a logical AND function - all inputs to the function must be "1" for the output to be "1."
"The AND function is one of several fundamental logic functions, but the most important one for computation is the NOT-AND or NAND function. This is one of several areas for further research," explains Keiichi Yano, a doctoral student at Toyko Uni. "We also wish to increase the speed and density of the CLCs to make them more practical for use.
He concludes: “I'm fascinated by how self-assembling molecules like those we use to make the CLCs give rise to phenomena such as logical functions."
