Multiphoton fabrication of freeform polymer microstructures containing graphene oxide and reduced graphene oxide nanosheets

Three-dimensional freeform polymer microstructures containing graphene oxide (GO) nanosheets were fabricated via two-photon polymerization using Rose Bengal (RB) as the photoinitiator. To prevent photothermal damage in fabricated polymer structures and impede the reduction level in the GO nanosheets, the femtosecond laser dose was controlled as low as possible at the laser wavelength of 720 nm appropriate for superior two-photon absorption of RB. Furthermore, the GO nanosheets in the fabricated microstructure can be converted into reduced GO (rGO) by precisely increasing the laser power and controlling the desired reduction positions. In this manner, GO and rGO nanosheets contained in the designated areas of the fabricated microstructures can be achieved.