Photoinitiated CVD antifouling coatings enable long-term stability of flexible multifunctional neural probes for chronic neural recording

Flexible neural probes with integrated recording, optical stimulation, and drug delivery capabilities offer unprecedented access to neural circuit dynamics. However, their long-term utility is compromised by foreign body responses that isolate recording sites from target neurons. This study introduces photoinitiated chemical vapor deposition (piCVD) as a transformative approach to neural interface stability through ultrathin (<100 nm) anti-fouling coatings. Unlike conventional hydrogel coatings that impair electrical signal transmission, our piCVD-applied poly(2-hydroxyethyl methacrylate-co-ethylene glycol dimethacrylate) coating maintains electrical functionality by preserving low impedance while providing superior anti-fouling properties. In vitro protein adsorption studies demonstrated near-complete resistance to both albumin and fibrinogen compared to uncoated surfaces, with the coating maintaining stability even after 24 h of sonication-durability unachievable with conventional wet-chemistry methods. When evaluated in mouse models over three months, the coated probe maintained high-quality spontaneous neural recordings and optically evoked potentials throughout the study period, with signal-to-noise ratios improving from 18.0 at week 1-20.7 at week 13. This performance significantly correlates with 66.6 % reduction in glial scarring, 84.6 % increase in neuronal preservation compared to uncoated probes. The specific combination of CVD methodology and optimized copolymer composition achieves long-term stability, representing a significant advance over the typical one-month limitation of conventional coatings. These results establish piCVD antifouling coatings as an enabling technology for chronic neural interfaces in both basic neuroscience research and emerging neuroprosthetic applications.