Neural Dust: An Ultrasonic, Low Power Solution for Chronic Brain-Machine Interfaces

A major hurdle in brain-machine interfaces (BMI) is the lack of an implantable neural interface system that remains viable for a substantial fraction of a primate lifetime. Recently, sub-mm implantable, wireless electromagnetic (EM) neural interfaces have been demonstrated in an effort to extend system longevity. However, EM systems do not scale down in size well due to the severe inefficiency of coupling radio waves at mm and sub-mm scales.

We propose an alternative wireless power and data telemetry scheme using distributed, ultrasonic backscattering systems to record high frequency (~kHz) neural activity. Such systems will require two fundamental technology innovations: 1) thousands of 10 – 100 um scale, free-floating, independent sensor nodes, or neural dust, that detect and report local extracellular electrophysiological data via ultrasonic backscattering, and 2) a sub-cranial ultrasonic interrogator that establishes power and communication links with the neural dust. We performed the first in vitro experiments which verified that the predicted scaling effects follow theory and that the extreme efficiency of ultrasonic transmission can enable the scaling of the sensing nodes down to 10's of um. Such ultra-miniature as well as extremely compliant implantable neural interface would pave the way for both truly chronic BMI and massive scaling in the number of neural recordings from the nervous system.