MIT Scientists Develop Flexible Metal-Free Electrode

MIT Scientists Develop Flexible Metal-Free Electrode

These Jell-O-like electrodes could eventually connect electronic implants with the human body.

By Ryan Whitwam June 20, 2023

The inexorable march of technological innovation continuously turns science fiction into science fact, and the next target may be the human body. With multiple companies moving toward human testing of bioelectronic implants, our cyberpunk future could be here before we know it, and a new project from MIT could play a crucial part. A team working with conductive polymers has succeeded in designing a soft metal-free electrode that can be 3D printed and attached directly to tissues.

The future of implantable technology could take many paths, but whether you're trying to restore vision, enhance mobility, or build a brain computer interface, you'll need an electrode to mediate the connection between gooey human and cold, unfeeling technology. Most electrodes, like the ones Elon Musk's Neuralink robot "sews" into the brain are composed of metal, which is naturally conductive. However, metals can cause tissue irritation over time, which leads to signal degradation.

Most polymers are natural insulators, so they cannot conduct signals. However, there is a class of conductive polymers, the discovery of which won a Nobel Prize in chemistry in the 1970s. Researchers working with mechanical engineering professor Xuanhe Zhao have experimented with several materials to produce soft, flexible electrodes. The team found some success by mixing conductive polymers with hydrogel, a gelatin-like polymer that is high in water content. However, this mixture didn't offer the right mix of conductivity and durability. "In gel materials, the electrical and mechanical properties always fight each other,” says collaborator Hyunwoo Yuk. “If you improve a gel’s electrical properties, you have to sacrifice mechanical properties, and vice versa."  .... '