• planar electrode
• regenerative neural interface
• peripheral nervous system
• thin film

The objective of this thesis is to present a novel design for a regenerative neural interface: the electrode presents a planar, double-sided design and is longitudinally inserted inside the guidance tube, therefore showing less physical barrier to the re- generating nerve with respect to the classical transversal electrodes. Longitudinal insertion divides the guidance tube in two equal volumes, creating a bi-chamber model, in which two different type of regenerating fibers belonging to the same nerve can be physically separated and selectively interfaced by one of the electrode side. The long-term goal is to promote the distinct regrowth of sensory and motor fibers and to guide the regenerating fibers to contact individual micro-electrodes. This will realize a high spatial resolution signal coupling, enabling the selective interfacing of a large number of sensory and motor fibers to the external robotic device. It will be therefore possible to extract the user movement intention and translate it into electrical output for the prosthesis, and transmit sensory feedback to the central nervous system through electrical stimulation.
To assess whether the electrode design supports nervous regeneration a pas- sive version (without printed circuit boards and electric wires) was developed and chronically implanted in the rat sciatic nerve. After 90 days the electrode and the segment of nerve were explanted and nerve regeneration was evaluated through macroscopical observation and histologic analysis.
A preliminary functional evaluation for acute trials was instead conducted using active version of the electrode implanted in acute. Electrophysiological test were conducted to evaluate the functionality of the electrodes and its capablility in stimulating the axons and eliciting muscle excitation. Evaluation of the stimulation selectivity was performed comparing the recruitment curves of muscles innervated by the sciatic nerve.