Breaking from the traditional rules of material engineering, a research lab at the University is working to effectively bend electronic devices.

The Kotov Laboratory at the University is working to give electronic devices increased flexibility.

Dr. Nicholas Kotov, a Chemical Engineering professor and member of the Materials Science and Engineering Department at the University, said stretchable conductors are materials that can be used in many electronic devices and help the device adequately bend and stretch.

The technology requires fundamental accessibility and availability of materials that can conduct electricity well and be mechanically transformable.

Stretchable conductors usually consist of material that is made up of polymers, such as rubber. These materials are not very conductive on their own; however, when combined with ductile metal wires, the versatility of the conductors increases.

According to Terry Shyu, a doctoral student in the Materials Science and Engineering department and member of the Kotov group, the ability to combine these two properties is very useful as society’s interest in flexible electronics, displays and even biomedical implants increases.

However, when improving conductivity of the material, flexibility is sacrificed.

“It is an interesting problem that would require an out-of-the box solution,” said Dr. Kotov. “The traditional approach that many people apply tends to compromise performance, so we decided to apply something outrageous.”

The “outrageous” approach Dr. Kotov referred to is Kirigami, the ancient Japanese art of paper cutting. The success of the Kotov group’s stretchable conductors lies in its usage of this technique.

“This idea started from playing with Kirigami paper sculptures from the artist Matt Shlian,” Shyu said. “We were interested in seeing how paper art — essentially a really robust mechanical system — can help us design materials.”

Shyu measured how materials respond under tension using a tensile test. What she and her colleagues found was that paper behaved comparably to polymeric material. They could now control the response of these materials by implementing various cutting patterns.

Kirigami is especially useful in stretchable conductors because the integrity of the material does not have to be compromised — in other words, the chemistry or composition of the material remains unaltered. The method also helps diminish uncontrolled failure by predetermining points of strain in the material, allowing for predictability of the electrical conductivity.

While other research focuses on a materials approach, what sets the Kotov group’s research apart is that it combines engineering material and geometry, allowing for the predictability of the deformation of the material.

“We are quite excited by initial experimental data,” Dr. Kotov said. “It means that instead of the dry methods of designing these conductors, we now have a really robust engineering computational tool which can be coupled with the composites and all together this creates a foundation for designing and mechanics of conductivity.”

The advent of effective stretchable conductors has the potential to be a game-changer in the world of electronics.

According to Shyu, an obvious path for stretchable conductors is flexible electronics, such as batteries and sensors.

“Many people are jumping on the idea of structuring deformation,” Shyu said.

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