1. A closed-loop DBS systemWhen deep-brain-stimulation is used to treat a tremor disorder, the surgeons can implant the electrodes in the brain while the person with the disorder is awake and then turn the stimulation on to see if the electrode is in the right place with correct stimulation settings, Wehde of Mayo Clinic explained last month at DeviceTalks Minnesota.
“But if you’re trying to use it to treat obsessive-compulsive disorder or depression, you can’t ask the patient, ‘Are you happy now?’ or, ‘Are you less obsessed?’ You just can’t do that in the operating room. So we needed another way to help figure that out,” Wehde said.
The solution that Mayo Clinic’s Division of Engineering has been working on is a closed-loop DBS system in which algorithms adjust treatment based on levels of neurotransmitters sensed in the brain. A couple of years ago, Mayo Clinic completed the development of its WINCS Harmoni Animal Use system to test the concept on animals, and it is now working on a third-generation human use version — the WINCS Maven — for studies on humans.
A major technological challenge involved the electrodes for sensing neurotransmitters, Wehde said. Carbon fiber electrodes only last a few days before they dissolve, so the DBS system developers turned to conductive diamond because of its hardness and durability. To produce the electrodes, they created a diamond reactor in which they inject methane, hydrogen, and trimethyl borane in a hot chemical vapor deposition reaction in order to create boron-doped conductive diamond electrodes.
The system deposits the conductive diamond on an inserted tungsten wire. The wire then goes into a parylene system, which puts an insulator around it, and then a femtosecond laser exposes the very tip, which is the active part of the electrode.
“These are the electrodes that we’re working on right now, and they certainly work a lot better than the carbon fiber electrodes did,” Wehde said.