A team of scientists from the University of Texas, Dallas, along with colleagues at the University of Tokyo, Japan, have created biologically adaptive transistor devices that have the ability to become soft when implanted inside the body yet can reshape themselves and deploy to grip 3D objects, such as large tissues, nerves, and blood vessels.
Their research, they say, is one of the first demonstrations of transistors that can change shape while still maintaining their electronic properties after they are implanted in the body, 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,” says Reeder. “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,” he says.
Shape memory 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. The team fabricated the devices with an organic semiconductor but used adapted techniques normally applied to create silicon electronics that could reduce the cost of the devices.
During testing, researchers used heat to deploy the device around a cylinder as small as 2.25 millimeters 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.