The FES Center, in collaboration with NDI Medical, a medical device development company, was interested in developing a completely implantable
stimulator for a newer version of the hand system, dubbed Micropulse II, that would include its own battery power and microprocessor, eliminating the need for any
external equipment except for a controller.
Another drawback of
external muscle
stimulators is that the high voltage needed to get through the skin can mess up the signals being recorded in the brain, says Lee Miller, a neuroscientist and biomedical engineer at Northwestern University in Evanston, Illinois, who was not involved in the project.