Ultraconformable Cuff Implants for Long-Term Bidirectional Interfacing of Peripheral Nerves at Sub-Nerve Resolutions

The peripheral nervous system is crucial for the communication between the brain and the rest of the body. Implantable devices interfacing with this part of the nervous system hold great potential for the development of treatments for a wide range of clinical conditions, whether by recording electrical activity carried by nerves, or influencing it through electrical stimulation. However, current nerve interfacing technologies lack the necessary resolution to selectively record and stimulate from nerves at the sufficient resolution and stability to enable their therapeutic use.<br/><br/>Here, we present a nerve cuff implant with an ultraconformable design that achieves high-quality and stable interfacing with nerves in chronic implantation scenarios. The cuffs are comprised of a parylene-C body 4 μm in thickness, rendering them highly flexible and able to conform to the surface of nerves. Combined with low impedance PEDOT:PSS microelectrodes, we show that these features allow the ultraflexible cuffs to record neural signals from awake animals for 21 days while exhibiting minimal fibrotic scarring. We furthermore show that high-resolution interfacing capabilities of the cuffs can be used to record action potentials with fascicle-specific resolution and extract from these physiologically-relevant features such as conduction velocity and direction of propagation. We evaluate the potential of this technology in two nerve systems in freely-moving rodent animal models: movement and sensory perception in the arm, and monitoring and control of bladder function.<br/><br/>The developed implantable devices represent a platform enabling new forms of fine nerve signal sensing and modulation, with applications in physiology research and closed-loop therapeutics.