Electronics that change shape inside the body

Researchers have developed electronic devices that become soft when implanted inside the body and can deploy to grip 3D objects, such as large tissues, nerves and blood vessels.

These biologically adaptive, flexible transistors, developed by The University of Texas at Dallas and the University of Tokyo researchers, are expected to help doctors learn more about what is happening inside the body, and stimulate the body for treatments. When heated, the devices can change shape and still maintain their electronic properties.

“Scientists and physicians have been trying to put electronics in the body for a while now, but one of the problems is that the stiffness of common electronics is not compatible with biological tissue,” said Jonathan Reeder BS’12, a graduate student in materials science and engineering and lead author of the work.

“You need the device to be stiff at room temperature so the surgeon can implant the device, but soft and flexible enough to wrap around 3D objects so the body can behave exactly as it would without the device. By putting electronics on shape-changing and softening polymers, we can do just that.”

The polymers respond to the body’s environment and become less rigid when they’re implanted. In addition to the polymers, the electronic devices are built with layers that include thin, flexible electronic foils first characterised by a group including Reeder in work published last year in Nature.

The rigid devices become soft when heated. Outside the body, the device is primed for the position it will take inside the body. During testing, researchers used heat to deploy the device around a cylinder as small as 2.25 mm in diameter, and implanted the device in rats. They found that after implantation, the device had morphed with the living tissue while maintaining excellent electronic properties.

“Flexible electronics today are deposited on plastic that stays the same shape and stiffness the whole time,” Reeder said. “Our research comes from a different angle and demonstrates that we can engineer a device to change shape in a more biologically compatible way.”

The next step of the research is to shrink the devices so they can wrap around smaller objects and add more sensory components, Reeder said. UT Dallas researchers and materials engineers Taylor Ware, David Arreaga-Salas and Adrian Avendano-Bolivar were also involved in the study.