Research engineers from Rice University have developed a surgical implant that can electrically stimulate the brain without a battery. This surgical implant or “neural stimulator” is powered by magnetic energy and produces the same kind of signals as the implants that are used for treating neurological conditions like Parkinson’s disease and epilepsy.
This grain-of-rice-sized implant has a thin film of “magnetoelectric” material that converts magnetic energy into electrical voltage. This implant, unlike others that use radio waves, ultrasound, or coils, does not produce a lot of heat, or suffer interference. As a proof of concept, the scientists implanted the stimulator into mice that were awake and roaming around; the implant worked with no issues.
"Doing that proof-of-principle demonstration is really important, because it's a huge technological leap to go from a benchtop demonstration to something that might be actually useful for treating people," said Jacob Robinson, corresponding author of the study and a member of the Rice Neuroengineering Initiative. "Our results suggest that using magnetoelectric materials for wireless power delivery is more than a novel idea. These materials are excellent candidates for clinical-grade, wireless bioelectronics."
While battery-operated implants are used for Parkinson’s and epilepsy, research shows that other conditions like depression and obsessive-compulsive disorders may benefit more from magnetic implants than electrical ones. Tiny implants are important because they can be placed almost anywhere in the body without invasive surgery. Lead study author, Amanda Singer, worked on the miniaturization.
Study co-author, Caleb Kemere said, "When you have to develop something that can be implanted subcutaneously on the skull of small animals, your design constraints change significantly. Getting this to work on a rodent in a constraint-free environment really forced Amanda to push down the size and volume to the minimum possible scale."
"When we first submitted this paper, we didn't have the miniature implanted version," Singer said. "Up to that point, the biggest thing was figuring out how to actually get that biphasic signal that we stimulate with, what circuit elements we needed to do that. When we got the reviews back after that first submission, the comments were like, 'OK, you say you can make it small. So, make it small.’ So, we spent another a year or so making it small and showing that it really works. That was probably the biggest hurdle. Making small devices that worked was difficult, at first."
Altogether, this study took more than five years to complete because all the materials were made from scratch. The study is published in the journal, Neuron.