Reconfigurable electrical circuit etched into a crystal

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A way to write an electrical circuit into a crystal which could enable transparent, 3D electronics that can be erased and reconfigured has been found by Washington State University physicists.

By using a laser to etch a line in the crystal and attaching electrical contacts at each end of the line, the researchers managed to create 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," said Professor Matt McCluskey. "It's exciting that it's reconfigurable. It's also transparent. Invisible electronics could be possible where a circuit is etched on a window or something like that.”

According to the team, a crystal does not ordinarily conduct electricity but when the crystal strontium titanate is heated under the right conductions, it is altered so light will make it conductive. The phenomenon, called ‘persistent photoconductivity’, also occurs at room temperature.

The researchers surmise that heat forces strontium atoms to leave the material, creating light-sensitive defects responsible for the persistent photoconductivity. Their recent work is said to increase the crystal's conductivity 1000-fold, which can last up to a year.

"We look at samples that we exposed to light a year ago and they're still conducting," said Prof McCluskey. "It may not retain 100% of its conductivity, but it's pretty big."

Moreover, the circuit can be by erased by heating it on a hot plate and recast with an optical pen.

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