Flexible Organic Transistors

Flexible Electronics

Electronic devices that become soft on command can be extremely useful for medical implants that would be able to wrap around different types of body tissues. Surgeons would be able to position the implant while it’s still stiff to let it gently wrap around the target tissue as it becomes soft. Researchers from the University of Texas at Dallas and the University of Tokyo have created mechanically flexible organic transistors able to do just that.

The investigators used shape-changing memory polymers that respond to the environment around them, staying tough initially at room temperature and becoming softer when warmed up to body temperature. The wiring within was made of a flexible foil that conforms to the shape of the device itself. Though they used an organic semiconductor, the scientitsts applied techniques normally meant for silicon-based electronics to build the device, to keep the complexity and cost down. The team tested the technology in the laboratory, successfully wrapping the device around a 2.25 mm wide rod and implanting it into rats without a loss of electrical properties. In the animal model, the device morphed to the shape of the tissues it found itself pushed around by, demonstrating the real world potential of the technology.

New Implanted Devices May Reshape Medicine

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, available online and in an upcoming print issue of Advanced Materials, 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 Jonathan Reeder BS’12, a graduate student inmaterials 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 said. “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.”

Here’s a video demonstrating the new adaptable flexible electronic technology: