Researchers from The University of Texas at Dallas and the University of Tokyo have created 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 might one day help doctors learn more about what is happening inside the body, and stimulate the body for treatments.
The research is one of the first demonstrations of transistors that can change shape and maintain their electronic properties after they are implanted, says Jonathan Reeder, a graduate student in materials science and engineering and lead author of the work.
“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,” he says. “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.”
Developed by Dr. Walter Voit, assistant professor of materials science and engineering and mechanical engineering, and an author of the paper, shape memory polymers are key to enabling the technology.
The polymers respond to the body’s environment and become less rigid when implanted. In addition to the polymers, the electronic devices are built with layers that include thin, flexible electronic foils.
The Voit and Reeder team from the Advanced Polymer Research Lab in the Erik Jonsson School of Engineering and Computer Science fabricated the devices with an organic semiconductor but adapted techniques normally applied to create silicon electronics to reduce the cost of the devices.
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 2.25mm in diameter and implanted the device in rats. After implantation, the device had morphed with the living tissue while maintaining excellent electronic properties.
The next step of the research is to shrink the devices so they can wrap around smaller objects and add more sensory components, Reeder says.