Direct stimulation of peripheral nerves with implantable electrodes successfully provided sensory feedback to amputees while using hand prostheses. Longevity of the electrodes is key to success, which we have improved for the polyimide-based transverse intrafascicular multichannel electrode (TIME). TIMEs were implanted in the median and ulnar nerves of three trans-radial amputees for up to six months. We present a comprehensive assessment of the electrical properties of the thin-film metallization as well as material status post explantation. The TIMEs stayed within the electrochemical safe limits while enabling consistent and precise amplitude modulation, leading to reliable performance in eliciting sensation. No signs of corrosion or morphological change to the thin-film metallization of the probes were observed. The longevity demonstrates that thin-film electrodes are applicable in permanent implant systems.

Paul Čvančara, Giacomo Valle, Matthias Müller, Inga Bartels, Thomas Guiho, Arthur Hiairrassary, Francesco Petrini, Stanisa Raspopovic, Ivo Strauss, Giuseppe Granata, Eduardo Fernandez, Paolo M. Rossini, Massimo Barbaro, Ken Yoshida, Winnie Jensen, Jean-Louis Divoux, David Guiraud, Silvestro Micera, Thomas Stieglitz