Ultrasound for brain stimulation

Implanted electrodes that deliver electrical pulses deep in the brain are often used to treat Parkinson’s disease and other neurological disorders by activating cells that produce the neurotransmitter dopamine. However, the electrodes can eventually corrode and accumulate scar tissue.

MIT researchers have now developed a way to use ultrasound instead of electricity, delivered by a biocompatible fiber as thin as a hair. The tip of the fiber contains a transducer with a vibrating membrane that encapsulates a thin piezoelectric film. When a voltage is applied, it generates ultrasonic waves that can elicit activity in nearby cells. The team calls the device ImPULS, for “implantable piezoelectric ultrasound stimulator.”

“It’s tissue-safe, there’s no exposed electrode surface, and it’s very low power, which bodes well for translation to patient use,” says graduate student Jason Hou, SM ’23, a lead author of a paper on the work, along with postdoc Md Osman Goni Nayeem. Canan Dagdeviren, an associate professor in the MIT Media Lab, is the senior author.

The researchers showed that in mice, the stimulation can trigger release of dopamine in the substantia nigra, an area often targeted in treatment of Parkinson’s. They say that in addition to its therapeutic uses—which could eventually include delivering drugs through a microfluidic channel, as well as ultrasound—this approach could be valuable for studying how the brain works.