In 2016, UC Berkeley engineers demonstrated the first implanted, ultrasonic, neural dust sensors. Now, taking the next step, the smallest-volume wireless nerve stimulator was developed, called StimDust (stimulating neural dust).
StimDust is implanted in the body through minimally invasive procedures to monitor and treat disease in a real-time, patient-specific approach. StimDust is 6.5 cubic millimeters in volume — about the size of a granule of sand — and is powered wirelessly by ultrasound, which the device then uses to power nerve stimulation at an efficiency of 82 percent. It stimulates almost all of the major therapeutic targets in the peripheral nervous system, which has been shown to be efficacious in treating a number of diseases.
The neural dust platform was used to build a more effective stimulator that can wrap around a nerve cuff and can also record, transmit, and receive data. A custom integrated circuit was created to transfer ultrasound charge to the nerve in a well-controlled, safe, and efficient way.
StimDust is about an order of magnitude smaller than any active device with similar capabilities. The components of StimDust include a single piezocrystal (the antenna of the system), a 1-millimeter integrated circuit, and one charge storage capacitor. StimDust has electrodes on the bottom that make contact with a nerve through a cuff that wraps around the nerve. In addition to the device, a custom wireless protocol was developed that provides a large range of programmability while maintaining efficiency. The entire device is powered by 4 microwatts, and has a mass of 10 milligrams.
StimDust could be used to treat diseases such as heart irregularities, chronic pain, asthma, or epilepsy.