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Studying spinal cord injuries requires a material that can transmit clear signals yet remain flexible for when patients move around. Researchers at ������Ƶ think they have hit upon a solution that will offer the best of both requirements.

In , Assistant Professor Siyuan Rao and her team have created a hydrogel electrode that includes conductive carbon nanotubes to monitor nerve activity. When integrated into bioelectronic devices, the hydrogel enables the recording of electrical signals from spinal cord neurons and leg muscles in mice.

“If you have a rigid material in a soft tissue, especially during movement, it’s going to cause a lot of damage,” said Rao, a faculty member at the Thomas J. Watson College of Engineering and Applied Science’s Department of Biomedical Engineering. “Our technology solves that fundamental problem, so we can pick up a single cell’s activity from the spinal cord and maintain the device’s functionality for a long time.”

Also part of the study are lecturer Sizhe Huang, PhD ’24; Assistant Professor Qianbin Wang; Associate Professor Fake “Frank” Lu; master students Ruobai Xiao ’24 and Chen Lin ’24; research technician Geunho Jang; PhD students Eunji Hong, Zuer Wu and Shovit Gupta; and collaborators from the University of Massachusetts, the University of Texas, Michigan State University, the Massachusetts Institute of Technology and the Boston Children’s Hospital.

The hydrogels used in the research are made from a synthetic plastic polymer that is nontoxic, shows good biocompatibility and has high absorbing capacity. Rao has previously investigated similar hydrogels to inhibit pain using light transmissions.

“You can imagine it as a sponge that contains a lot of water and the conductive material, which are the nanocarbon tubes invisible to the naked eye because they’re so small,” Huang said. “Those conductive nanomaterials are filling the free space in the 3D network.”

Although her previous work focused on the brain, Rao is hopeful that she and her team can leverage their ideas about soft materials engineering to answer questions about the spinal cord system.

“We are strengthening our capability to cover multiple regions of the nervous system,” she said. “Ultimately, we hope to have an effective tool to probe the different parts of the body and the causal link between the central nervous system and peripheral nervous system.”

Huang — who spearheaded the Nature Communications paper as part of his PhD research at Rao’s — believes he grew as a leader by supervising the work of undergraduates and master’s students.

“It’s like we’re in a car,” he said. “I’m in the driver’s seat, and all of the master’s students are my passengers — but they don’t just sit in the car. They also contribute, like one of them is keeping an eye on the maps to tell me directions, or I tell them directions. That’s how we work.”

The next challenge is to research pain inhibition and motor functional recovery in the spinal cord region.

“We specifically want to look at the ventral horn motor neurons that control voluntary movement,” Rao said. “We will build on our past research to use light to achieve pain inhibition and then use this new conductive material to pick up electrophysiological signals.”