Etch A Circuit Electronics

Physicists at Washington State University have used a laser to write an electrical circuit into a crystal. This new technique changes the nature of the usually nonconductive crystal, therefore making transparent, three-dimensional electronics that can be erased and reconfigured possible. In other words, the development could lead to invisible, changeable, Etch-a-Sketch style electronics.

The phenomenon was discovered by WSU researchers four years ago by accident when a doctoral student left a crystal exposed to light, which lead to a 400-fold increase in its electrical conductivity. Now, WSU professor of physics and materials science Matt McCluskey has etched a line into the crystal with a laser and placed electrical contacts at each end, enabling the crystal to carry a current.

“It opens up a new type of electronics where you can define a circuit optically and then erase it and define a new one,” McCluskey told “It's exciting that it's reconfigurable. It's also transparent. There are certain applications where it would be neat to have a circuit that is on a window or something like that, where it actually is invisible electronics.”

Better Materials, Simpler Processes

Although crystals typically do not conduct electricity, under the right conditions strontium titanate crystals can be heated and altered so that light can render them 1,000 times more conductive, a new attribute that can last for up to one year. This “persistent photoconductivity” phenomenon can also take place at room temperature, making it a major improvement over materials that must be cooled with liquid nitrogen. The circuit can also be erased with heat and then recast using an optical pen.

“It's an Etch A Sketch,” McCluskey said to “We've done it a few cycles. Another engineering challenge would be to do that thousands of times.”

Share This Article