Chronic coating stability, delamination & biofouling

Every high-performance interface material must survive years in a warm, saline, reactive, mechanically active environment, and chronic stability, not day-one impedance, is the true bottleneck. The dominant failure modes are coating delamination (loss of adhesion between a soft coating and its rigid substrate under swelling and micromotion), oxidative or hydrolytic degradation of the polymer or its dopant, dissolution or corrosion of the metal or oxide under stimulation, and biofouling (protein adsorption and glial encapsulation) that raises impedance from the tissue side.

Reported gains from PEDOT, carbon nanotubes, or nanostructuring measured acutely often decay over weeks to months, and the literature is uneven in how honestly it reports this. Mitigations, including adhesion primers and covalent anchoring, cross-linked or composite films, conformal barrier encapsulation, and anti-fouling surface chemistries, improve but do not yet solve chronic durability, which remains the central open problem of the electrode-materials frontier.