How shape-memory polymers may advance treatment of neurodegenerative diseases


Flexible displays, electronics and even batteries are currently being tested and will be part of our daily lives in a matter of years. The technology also holds tremendous promise for medical research and could contribute to treatment of Alzheimer's disease and a host of other conditions, says Walter E. Voit, PhD, an assistant professor specialized in materials science and engineering and mechanical engineering at the University of Texas, Dallas.

"Flexible electronics has tremendous potential in neural interface research to more fully understand and map neural circuits and possibly treat conditions associated with Alzheimer's disease, schizophrenia, tinnitus, Parkinson's, diabetes and more," says Voit. One challenge in advancing this technology is materials-related, and plastics may offer a path to success.

"Stiff implants can lead to scar formation, which blocks their ability to electrically "talk" to nerves," says Voit. On the other hand, a certain amount of stiffness is necessary to allow insertion of the device. Two companies have made significant advances in the development of silicon-based in vivo arrays—NeuroNexus (Ann Arbor, MI), which was acquired by Greatbatch (Frisco, TX) in 2012, and BlackRock Microsystems (Salt Lake City), says Voit. But stiffness remains an issue. He wants to take the technology a step further by using shape-memory polymers.

While polymer-based devices are more flexible, "even polyimide probes are still relatively stiff compared with tissue. Polydimethylsiloxane (PDMS) is softer, but still stiffer than tissue," says Voit. "Think of the brain, in terms of consistency, as a mass of gelatin. PDMS is like a rubber band, lacking buckling rigidity. You can imagine the difficulty of trying to insert a rubber band into Jell-O," he says. "Our lab uses a shape-memory polymer that goes from stiff to soft in a narrow window. As it softens, it is much closer to the modulus of tissue, but the material has good insertion properties in its stiff state," explains Voit.

Voit will discuss current and emerging technologies in flexible electronics at the MD&M East exhibition and conference, co-located with PLASTEC East, in New York City. The events run from June 9 to 11.
At the Advanced Polymer Research Lab at the university, Voit and his research team are using the shape-memory polymer platform to build biocompatible, functionalizable, self-softening substrates for flexible neural electronics. They are testing in vivo cortical probes and are developing self-coiling nerve cuff electrodes that can be inserted at 1 GPA and soften toward 300 kPA.

Voit has received a $1 million Young Faculty Award from the Defense Advanced Research Project Agency (DARPA) of the U.S. Department of Defense to pursue related research. DARPA funding is going toward the use of shape-memory polymers in micro-stimulation devices that will enable improved control of prosthetics used by wounded soldiers.

Voit will lead a session at MD&M East on Wednesday, June 10, exploring the shape-shifting future of flexible electronics. In addition to the technology's medical applications, he will review recent and emerging developments in printed, organic and flexible electronics and explain how novel academic breakthroughs can be applied to existing technology.

The premier east coast medical manufacturing exhibition and conference, MD&M East is co-located with PLASTEC East at the Jacob K. Javits Convention Center in New York City from June 9 to 11, 2015.
Source: Plastics Today