Ultrasonic microstimulator (StimDust)

The stimulating counterpart of a recording neural-dust mote: a millimetre-scale, battery-free implant that harvests ultrasound for power and delivers electrical stimulation to a nerve, rather than reading from it. Demonstrations such as StimDust have driven peripheral-nerve stimulation from a roughly cubic-millimetre device at very low power, with the external transducer setting stimulation timing and amplitude acoustically.

Ultrasonic microstimulators are attractive for distributed, leadless peripheral-nerve and bioelectronic-medicine applications, where many small motes might be placed and addressed acoustically. The open problems mirror those of recording motes — independently addressing many devices, delivering enough charge safely from a tiny electrode, maintaining alignment, and chronic biocompatibility.