Free-standing PEDOT: PSS/PLA bilayer nanosheets with ink-jet patterned microelectrodes: Towards the development of ultra-thin, conformable, floating circuits and smart biointerfaces

Novel solutions and applications in the biomedical field could come from exploiting the electroactive properties of conducting polymers towards the development of responsive smart biointerfaces and of flexible, conformable, biocompatible systems. In this sense it is mandatory to control material's conductivity in situ and this requires the development of suitable patterning processes and the fabrication of individually addressable microelectrodes. Based on the recent introduction by our group of free-standing nanofilms of conductive polymers, the aim of this work was to describe a method for the fabrication of patterned ultra-thin free-standing PEDOT:PSS/Poly (lactic acid) (PLA) bilayer nanosheets. The proposed method involves an inkjet patterning technique, based on localized overoxidation of PEDOT:PSS by means of a sodium hypochlorite solution. Here we described the fabrication method and characterized the realized nanosheets in terms of their thickness, contact angle, conductivity. The overall process permitted to realize patterned free-standing nanosheets that, despite their low thickness, are very robust and conformable on tissues or on soft and rigid substrates, while allowing for an electrical control of their surface properties. Possible applications are foreseen in the field of conformable electronics, e.g. as electrodes on the brain or smart conductive substrates for cell culturing and stimulation.