Acute Stimulation Selectivity of Minimally Invasive Interfascicular Nerve Stimulation (MIINS) in a Large Animal Model (June 2026)

Interfascicular peripheral nerve interfaces may offer a balance of high selectivity and reduced invasiveness across peripheral nerve stimulation applications. This study compares the stimulation selectivity of the Minimally Invasive Interfascicular Nerve Stimulation (MIINS) interface with that of the extraneural Composite Flat Interface Nerve Electrode (C-FINE) in a porcine model. Microcomputed tomography (micro-CT) quantified the placement of MIINS contacts relative to the fascicles and to the other contacts within the nerve.

Muscle selectivity was assessed with electromyography (EMG) across 13 MIINS and 7 C-FINE trials in the median nerves of Yorkshire pigs. Micro-computed tomography characterized 126 total MIINS microwire placements across 26 nerves of the brachial plexus.

Both devices achieved muscle selectivity: C-FINE selectively activated 3.00 ± 0.82 muscles, and MIINS selectively activated 2.38 ± 0.96 muscles out of the 5 total muscles sampled. MIINS achieved this with fewer contacts. Micro-CT confirmed that 89% of MIINS microwires were placed interfascicularly, with the majority (74%) localized to the central half of the nerve cross-section.

Acute muscle selectivity and micro-CT characterization of electrode placement in the median nerves of Yorkshire pigs demonstrated MIINS's feasibility and capability to achieve high selectivity and distributed interfascicular contact placement. MIINS achieved selective muscle recruitment comparable to that of the C-FINE and other existing intrafascicular designs in the literature. The data also show that in large nerves, higher anatomical invasiveness does not guarantee superior selectivity.