May 14, 2014
Researchers Create Softening, Shape-Changing Implanted Devices
[ Watch the Video: Adaptive Organic Transistors For Implantable Electronics ]
redOrbit Staff & Wire Reports - Your Universe OnlineResearchers from The University of Texas at Dallas and the University of Tokyo have created a biologically adaptive, flexible device that becomes soft when implanted inside the human body, allowing it to grip 3-D objects such as large tissues, nerves and blood vessels.
The research is one of the first demonstrations of transistors that can change shape and maintain their electronic properties after they are implanted in the body, said the study’s lead author, Jonathan Reeder, a graduate student in materials science and engineering at University of Texas at Dallas.
The breakthrough might one day help doctors learn more about what is happening inside the body, and stimulate the body for treatments, the researchers said.
“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,” Reeder told the UT News Center.
“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 3-D 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 driving force behind the technology is shape memory polymers developed by study co-author Dr. Walter Voit, assistant professor of materials science and engineering and mechanical engineering at UT Dallas. The polymers respond to the body’s environment, and become less rigid when they’re implanted, he said.
The electronic devices are also built with layers that include thin, flexible electronic foils first characterized by a group including Reeder in work published last year in Nature.
Voit, Reeder and colleagues fabricated the current devices with an organic semiconductor, but used adapted techniques typically applied to create silicon electronics to reduce costs.
“We used a new technique in our field to essentially laminate and cure the shape memory polymers on top of the transistors,” said Voit. “In our device design, we are getting closer to the size and stiffness of precision biologic structures, but have a long way to go to match nature’s amazing complexity, function and organization.”
The rigid devices become soft when heated. Outside the body, the device is primed for the position it will take inside the body.
During the testing phase, the researchers used heat to deploy the device around a cylinder as small as 2.25 millimeters in diameter, and then implanted the device in rats. After implantation, they found the device had morphed with the living tissue while maintaining exceptional 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.”
Reeder said the next step is to shrink the devices so they can wrap around even smaller objects, and to add more sensory components.
The research is published online and in an upcoming print issue of the journal Advanced Materials.