An implantable bioelectronic device, comprising: a flexible insulating substrate; a conductive circuit layer disposed on the flexible insulating substrate and comprising an array of electrodes comprising one or more electrodes; an insulating encapsulation layer encapsulating the conductive circuit layer and comprising an opening, wherein the electrodes are exposed through the opening; and a conductive adhesive interface layer disposed on the insulating encapsulation layer and comprising an exposed surface and a filling portion that seals the opening, wherein the exposed surface is electrically connected to the electrodes through the filling portion, the conductive adhesive interface layer comprises a hydrophilic polymer and a hydrophobic polymer, and wherein the hydrophobic polymer is formed by polymerization of 3-(trimethoxysilyl)propyl methacrylate (TPM) monomers.