Flexible electronics are all the rage these days, as their development could boost a generation of devices that can be worn on our wrists or embedded in our clothes. But a laboratory at the University of California, San Diego wants to move beyond flexible electronics into devices that are actually stretchable, allowing them to conform to almost any shape instead of just bending.
UC San Diego nanoengineering professor Darren Lipomi likened flexible electronics to folding a piece of paper around a basketball. Stretchable electronics, on the other hand, are more akin to wrapping rubber around the ball; they conform perfectly with no wrinkles.
Stretchy materials would also have the benefit of being far less breakable. If you dropped a heavy object on your current phone, you would probably worry about the screen breaking. But a stretchy device would just bend around the object instead of breaking. As a result, the lab’s flexible materials could be used to create objects like solar cells that are less vulnerable to damage.
“I am personally excited by the potential for molecularly stretchable electronics because the most sophisticated devices that we know of–that is, biological organisms–are soft and compliant,” Lipomi said. “Our interest in compliant and fracture-proof solar cells excites me and many of my students because we want to contribute in a unique way to the production of clean energy.”
The team’s work will compliment other early forays into stretchable electronics. Cambridge-based startup MC10 is already commercializing a group of stretchable devices that includes skin patches that can monitor the human body. Graphene and carbon nanotubes, both emerging materials renowned for their impressive electrical and physical properties, are also inherently stretchable. Large companies like Samsung are pushing to integrate them into devices.
But creating perfectly stretchy electronics involves diving down to their molecular structure and optimizing every single material that goes into them for stretchability and electronic properties. In a paper published in the journal Chemistry of Materials (subscription required), Lipomi’s team weighed different methods for creating flexible materials. The group found that there are already several combinations that could be suitable for personal devices or solar cells, though future work could further improve their properties. Lipomi noted the prototypes his lab has made (pictured above) are not quite ready to jump from the lab to our personal devices just yet:
“Barriers that remain before this technology can be commercialized involve protecting the sensitive stretchable semiconductors from oxygen and water vapor, which degrade the properties of the devices,” Lipomi said. “So, we need barriers in the literal sense: stretchable, transparent films that exclude water and oxygen.”