High-density Neural Recordings from Feline Sacral Dorsal Root Ganglia with Thin-film Array

Dorsal root ganglia (DRG) are promising sites for recording sensory activity. Current technologies for DRG recording are stiff and typically do not have sufficient site density for high-density neural data techniques. We demonstrate neural recordings in feline sacral DRG using a flexible polyimide microelectrode array with 30-40 μm site spacing. We delivered arrays into DRG with ultrananocrystalline diamond shuttles designed for high stiffness with small footprint. We recorded neural activity during sensory activation, including cutaneous brushing and bladder filling. We successfully delivered arrays in 5/6 experiments and recorded sensory activity in 4. Median signal amplitude was 55 μV and the maximum unique units recorded at one array position was 260, with 157 driven by sensory or electrical stimulation. We used specialized high-density neural signal analysis software to sort neural signals and, in one experiment, track 8 signals as the array was retracted ~500 μm. This study is the first demonstration of ultrathin, flexible, high-density electronics delivered into DRG, with capabilities for recording and tracking sensory information that are a significant improvement over conventional DRG interfaces.