One of the most important challenges that remains in neuroengineering is the development and demonstration of a clinically viable neural interface which can both record from and stimulate many individual neurons and lasts a lifetime. These chronic or long-term neural interfaces are of increasing interest for both central (CNS) and peripheral nervous system (PNS) interventions. Creating lasting, durable, untethered interfaces raises a variety of issues, ranging from the nature of the physical substrate (avoiding the biotic and abiotic effects that presumably lead to performance degradation at the electrode-tissue interface, the density and spatial coverage of the sensing sites), the type of signals measured, and the computation and communication capabilities (how much signal processing on-chip data to transmit wirelessly) under the power budget of the whole system. This proposal seeks to extend our recently published Neural Dust platform to allow for stimulation of nerves via neural dust motes. We believe this to be an aggressive vision which would open the door to a vast array of interventions, including untethered neural recording of human nerves and neurons, untethered stimulation of these processes and record-and-stimulate closed loop systems. Such a vision will require a number of fundamental technological innovations that will have impact across domains including basic neuroscience, clinical interventions of neurological disorders, and prosthetics. For example, the ability to precisely monitor and modulate peripheral nerve activity with a minimally invasive medical device would enable a wide-range of therapeutic opportunities. This closed-loop neuromodulation cannot be done with existing technologies because they suffer from one of two major drawbacks: lack of spatial resolution or high degree of invasiveness.
We recently proposed an ultra-miniature as well as extremely compliant system that could enable massive scaling in the number of recordings from the brain or the peripheral nervous system, providing a path towards truly chronic BMI. At the core of this vision is a platform for powering, receiving and transmitting information from inside a peripheral nerve to outside the body using aggressive, state-of-the-art circuit design and the recent demonstration of ultrasonic, piezocrystal "neural dust? motes. The work envisioned in this proposal will leverage recent application specific integrated circuit (ASIC) technology to build stimulating motes that can address individual neurons (or peripheral fibers) and will demonstrate untethered stimulation of nerve fibers, paving the way to closed-loop record-and-stim technology using neural dust. This is a very aggressive, high risk direction which leverages existing neural dust developments with a very high potential payoff (as it enables untethered closed-loop neuromodulation systems). Our long term vision is a system capable of recording and stimulation in closed-loop.