Get Creative with a New Kind of Circuitry

After its super photoconductivity was discovered accidentally, crystal can be turned into an electrical circuit, using light.

Scientific serendipity has its ways. Sometimes, scientists would be looking for one thing only to stumble on another. Mistakes often lead to unexpected developments.

Through accidental strokes of luck, many scientific discoveries and inventions have come to be a reality, including: X-rays, penicillin, photography, plastic, Vaseline, Post-it notes, Viagra, corn flakes, and the list goes on.

Crystal’s “Persistent Photoconductivity” Discovered by Accident

A Washington State University student didn’t know that serendipity was awaiting her after she left the lights on.

In 2013, Marianne Tarun, then a doctoral student at WSU, was working on a strontium titanate crystal. One day, she left the sample exposed on a countertop and forgot to turn the light off in the lab.

When she came back the next day, she discovered that the sample’s electrical conductivity was drastically improved.

At first, Tarun and her colleagues thought the sample was contaminated, but upon further investigation they concluded that it was the exposure to light that induced this effect.

In fact, the accidental exposure to light made the crystal’s conductivity shoot up by 400%. The effect persisted for several days even with the light turned off.

This phenomenon, called “persistent photoconductivity”, has already been stimulated and studied in some materials, however, this was the first time the phenomenon was shown to be effective at room temperature.

“The discovery of this effect at room temperature opens up new possibilities for practical devices,” said Matthew McCluskey, chair of WSU’s physics department.

Light-Drawing an Electrical Circuit Into Crystal

Researchers didn’t stop there and, after four years, have found practical application for their chance discovery.

WSU’s physicist announced they succeeded in etching, or rather, drawing, an electrically conductive circuit into a crystal at room temperature.

In their new work, a study on which was published in the journal Scientific Reports, researchers increased the crystal’s photoconductivity up to 1,000 times, which persisted for up to a whole year.

The team compares their proof of concept to Etch A Sketch drawing toy, because it allows writing, by a simple laser, erasable and reconfigurable electrical circuits.

If the Etch A Sketch has to be shaken to erase drawings and start again, to erase electrical circuits using the WSU technique, the crystal circuit must be heated.

This new technique paves the way for the emergence of new 3D, transparent electronics with reconfigurable circuits.

What things have you discovered on accident?