Monolithic 3D Neuroelectronics from BEOL Deterministic Rolling

To fully decode brain functions/dysfunctions and unlock brain-computer-interface potential, neural recording needs to be performed with high spatiotemporal resolution across three dimensions. This project will investigate a set of foundational flexible-electronic design and systems research problems to, for the first time, establish a new neural probe paradigm, a monolithic 3D neuroelectronic system. This program will not only produce a powerful tool for neuroscience research and investigating/diagnosing nervous system disorders but also create unique opportunities for novel prostheses and brain-computer interfaces. The team will maximize the broader impacts of our research by intersecting with (1) systems-based bioelectronic education, (2) K-12 outreach and undergraduate research, and (3) semiconductor workforce development. Cognition and behavior both rely on coordinated activity from neural circuits distributed in 3D. However, to date, the mainstay neural devices are constrained to 2D interfacing with the brain, largely due to the predominant planar semiconductor fabrication process that produces these devices. The investigator hypothesizes that a simple back-end-of-line (BEOL) rolling process can transform appropriately designed, post-fabricated flexible electronics into a 3D neuroelectronic probe with monolithicity and highly controlled electrode and shank distribution. This project will holistically test this hypothesis through novel rolling process development and corresponding design rule establishing, innovative neuroelectronic design and fabrication, chronic bench characterization, and in vivo system validation. The unprecedented monolithic 3D neuroelectronics will yield profound impacts not only for studying and connecting with the brain but also for a wide range of electroactive tissues, including peripheral nervous systems, cerebral organoids, and engineered nerve scaffolds. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.