Abstract: The manufacture of an electrochemical sensor precursor comprising the steps of: preparing an electrically conductive biocomposite comprising an aqueous mixture of: polycationic conductive polymer particles; an anionic polyelectrolyte; or pre-existing composites of polycationic conducting polymers and anionic polyelectrolytes a biological affinity agent; and an optional buffer; applying the mixture to a region of an electroconductive surface; and removing water to allow adhesion of the biocomposite to the region of the surface.