Hearing implant harnesses platinum and iridium

“Doctors have highlighted a new surgical procedure to restore hearing in deaf people that utilises activated iridium implants to directly stimulate nerve cells.
For the first time surgeons have placed the implants directly on the brain stem – a risky procedure as the stem carries signals from the entire body to the brain.”
Stem cell? Oh boy. I can’t imagine who’d want to be the first set of volunteers.