Investigations on stability of implanted nervous thin-film electrodes

Many micromachined neural implants with multi-channel thin-film electrodes have been presented over the last decades. A transverse intrafascicular multi-channel electrode (TIME) was developed for translational research to treat phantom limb pain (PLP). Four TIME systems (latest electrode version) have been implanted for 30 days into the arm of an amputee. After finishing successfully the clinical trials the TEVIE-3H systems have been explanted. The material composition of the electrode contacts used for stimulation have been investigated with X-ray photoelectron spectroscopy (XPS). System integrity has been examined using focused ion beam (FIB) and pictures were acquired using the integrated scanning electron microscope (SEM). Both methods revealed that the metallization was still intact after explantation and that no delamination occurred. Crack formation without delamination was observed but it could not be determined if it originated while the implant was inside the body or during the explantation or during the cleaning of the implants.