We have seen many incredible inventions and ideas come true with continuous technological innovations. The smartphones and electric cars we consider to be so common today were also once part of our imaginations of a fascinating future. This time, stretchable displays and devices are the ones projected to be as conventional as smartphones in the near future. Korea University’s (KU) Professor Han Chang-Soo (School of Mechanical Engineering) and his research team have recently announced the key technology that could be used in all applications of stretchable displays.

Professor Han and his team have collectively worked together in successfully creating the key technology behind stretchable devices. The authors and researchers consist of professors and researchers from various backgrounds such as Son Yeong-jun, Professor Bae Jin- woo, and Lee Ho-Jung. The team had been studying human tactile senses, which all have stretchable properties, when they decided to study the materials used for stretchable devices.

Stretchable devices are an advanced form of *flexible devices* that can mold to non-linear surfaces. Stretchable devices are more advanced in that they can be further stretched yet still function well. “The first of the stretchable devices were stretchable conductors, like coiled telephone wires in the 19th century,” explains Professor Han. “As micro-nano scale and material handling techniques evolved, more inventions such as stretchable electrodes, electronic skin, and implantable devices are being made.”

For stretchable devices, the materials that make them are most important. Because these devices aim for long- term use, they should maintain their shape for a long time and not be distorted by changes in temperature or humidity. Flexible devices were usually produced with hydrogel, a gel-type material with “more than 10 times more liquid in a polymer network.” However, as the water in the gel evaporates, it becomes less durable. Professor Han’s technology uses non-volatile ion gels to address its shortcomings for stretchable devices.

Before settling on these materials, Professor Han had been facing trouble with experiments on other tactile materials. “I was almost at the point of giving up on this field of research.” The team eventually followed through with a new material and shortly reached successful results. Professor Han shares that he was happy to see the looks of fulfillment on everyone’s faces after the continued rounds of failure.

There are many papers and patents related to stretchable devices, but no products have been commercialized yet. “We expect commercialization to be five to ten years from now on,” hopes Professor Han. Stretchable devices are projected to be more portable, space- use developed and more human-friendly in the future, through electronic devices like televisions and cell phones, as well as health monitoring and medical implant devices.

Professor Han’s team is currently developing a stretchable touch panel using ion gel while also continuing their studies on stretchable electronic skin. “As I always pursue new things, there were times where I just lingered on the ideation stage for a long time,” recalls Professor Han. “I expect to face more of these challenges in the future, but I will continue to strive for better research outcomes.”