Two-photon polymerization of conductive polymer network inside a thermoresponsive hydrogel

Hydrogels with mechanical strength comparable to biological tissues show promising potential in flexible electronics through imparting conductivity. In this study, we demonstrated the spatially selective fabrication of conductive polymer, polyaniline, inside a thermoresponsive hydrogel by two-photon polymerization. A thermoresponsive hydrogel, poly (N-isopropylacrylamide) (PNIPAM), was immersed in an aqueous solution of a polyaniline precursor and irradiated into the hydrogel by femtosecond laser pluses. After the irradiation, the black structure was observed. Fourier transform infrared (FT-IR) and Raman spectroscopic analyses revealed that the fabricated structure consists of polyaniline. The proposed method would realize the spatially selective fabrication of conductive polymer inside a hydrogel.