Sprout-inspired polypyrrole-integrated electrodes for reduced impedance and enhanced biological compatibility†

Creating coatings on the electrode surface is a promising strategy to isolate the electrode surface from biological contamination and minimise the interference of foreign body reactions. However, this can also lead to an increase in the impedance of the implant, thereby affecting its working performance. In this paper, through electrochemical oxidation, polypyrrole is grown between the sulfobetaine methacrylate coating and the electrode in a manner similar to seed germination. The modified electrode (CE) not only shows lower impedance and higher capacitance than the bare electrode, but also exhibits resistance to the adhesion of proteins, bacteria, and fibroblasts. In vivo animal experiments demonstrate that the CE leads to milder inflammation and fibrous encapsulation. In vitro analogue signal monitoring experiments further demonstrated the potential of the CE as a long-term implantable bioelectrode. In addition, the unique way in which conductive substances grow on SBMA coatings is a new discovery that may facilitate research in other subject areas.