Researchers at Washington State University have discovered a way of stretching metal circuitry to twice its size, possible solving one of the biggest challenges in the growing field of flexible electronics. The discovery was made by a team from Voiland College’s School of Mechanical and Materials Engineering, that includes Associate Professor Rahul Panat, Professor Indranath Dutta and graduate student Yeasir Arafat.
Still in its infancy, flexible electronic technology could open the door to new and exciting products such as bendable batteries, flexible displays, connected fabrics, and robotic skins. Pioneers in this field have struggled to build the devices in their dreams because of limitations in metallurgy. They just couldn’t stretch metal far enough and thin enough to fit their product and still conduct electricity. Manufacturers developed a workaround using tiny metal springs, but the springs are difficult to work with because they are bulky and require more power and bigger batteries to conduct electricity efficiently. “The circuitry ends up requiring a ton of real estate and bulky batteries,” said Panat.
Researchers have experimented with gold and copper circuitry with less than ideal results. Gold stretches better than other materials, but it is too cost prohibitive to use on a large scale. Copper is already used in electrical circuits, but it becomes brittle when stretched as little as 30 percent. The Washington State University researchers decided to look at indium, a soft and malleable metal already used in electronics. When bonded to a plastic layer, researchers were able to stretch the metal film to more than twice its original length without breaking. They may have been able to stretch the metal even further, but the plastic layer broke, ending the experiment.
Panat is excited about his discovery, noting that it “is a quantum improvement in stretchable electronics and wearable devices.” The team plans to study the properties of the metal further with the hope of one day commercializing the process so it can be used effectively in the production of flexible electronics.