Strong adhesion of wet conducting polymers on diverse substrates.

Conducting polymers such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), polypyrrole (PPy), and polyaniline (PAni) have attracted great attention as promising electrodes that interface with biological organisms. However, weak and unstable adhesion of conducting polymers to substrates and devices in wet physiological environment has greatly limited their utility and reliability. Here, we report a general yet simple method to achieve strong adhesion of various conducting polymers on diverse insulating and conductive substrates in wet physiological environment. The method is based on introducing a hydrophilic polymer adhesive layer with a thickness of a few nanometers, which forms strong adhesion with the substrate and an interpenetrating polymer network with the conducting polymer. The method is compatible with various fabrication approaches for conducting polymers without compromising their electrical or mechanical properties. We further demonstrate adhesion of wet conducting polymers on representative bioelectronic devices with high adhesion strength, conductivity, and mechanical and electrochemical stability.