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Phoenix666 writes:

researchers have developed a rubber-like fiber that can flex and stretch while simultaneously delivering both optical impulses, for optoelectronic stimulation, and electrical connections, for stimulation and monitoring. The new fibers are described in a paper in the journal Science Advances, by MIT graduate students Chi (Alice) Lu and Seongjun Park, Professor Polina Anikeeva, and eight others at MIT, the University of Washington, and Oxford University.

"I wanted to create a multimodal interface with mechanical properties compatible with tissues, for neural stimulation and recording," as a tool for better understanding spinal cord functions, says Lu. But it was essential for the device to be stretchable, because "the spinal cord is not only bending but also stretching during movement." The obvious choice would be some kind of elastomer, a rubber-like compound, but most of these materials are not adaptable to the process of fiber drawing, which turns a relatively large bundle of materials into a thread that can be narrower than a hair.

[...]The team combined a newly developed transparent elastomer, which could act as a waveguide for optical signals, and a coating formed of a mesh of silver nanowires, producing a conductive layer for the electrical signals. To process the transparent elastomer, the material was embedded in a polymer cladding that enabled it to be drawn into a fiber that proved to be highly stretchable as well as flexible, Lu says. The cladding is dissolved away after the drawing process.

After the entire fabrication process, what's left is the transparent fiber with electrically conductive, stretchy nanowire coatings. "It's really just a piece of rubber, but conductive," Anikeeva says. The fiber can stretch by at least 20 to 30 percent without affecting its properties, she says.

Original Submission