An Implantable Wireless Network of Distributed Microscale Sensors for Neural Applications.

A vastly enhanced capability to bi-directionally interface with cortical microcircuits in a clinically viable way is the ultimate aspiration in neuroengineering. This necessitates a paradigm shift in neural interface system design beyond current bulky, monolithic constructs which are challenging to scale past 100-200 channels due to anatomic and engineering design constraints. A neural interface system relying on a spatially-distributed network of wireless microscale implantable sensors offers a highly scalable, robust and adaptive architecture for next-generation neural interfaces. We describe the development of a wireless network of sub-mm, untethered, individually addressable, fully wireless "Neurograin" sensors, in the context of an epicortical implant. Individual neurograin chiplets integrate a ~ 1 GHz wireless link for energy harvesting and telemetry with analog and digital electronics for neural signal amplification, on-chip storage, and networked communications via a TDMA protocol. Each neurograin thus forms a completely self-contained single channel of neural access and is implantable after post-process atomic layer deposition of thin-film (100 nm thick) barriers for hermetic sealing. Finally, ensembles of implantable neurograins form a fully wireless cortico-computer communication network (utilizing their unique device IDs). The implanted network is coordinated by a compact external "Epidermal Skinpatch" RF transceiver and data processing hub, which is implemented as a wearable module in order to be compatible with clinical implant considerations. We describe neurograin performance specifications and proof-of-concept in bench top and ex vivo and in vivo rodent platforms.