Rapid hot embossing of polymer microstructures using carbide-bonded graphene coating on silicon stampers

In this study, we present a novel rapid hot micro-embossing technique utilizing micro-patterned silicon stampers coated with a newly developed carbide-bonded graphene network to implement rapid heating and cooling. The graphene coating layer is highly thermally conductive and a ~ 45 nm thick coating layer on silicon wafer could serve as a highly efficient heating film because of its high electrical conductivity of 1.98 × 104 S/m and low surface resistivity of 20.4 Ω. Heating rates of 5-10 °C/s could be achieved by employing a DC operating voltage under 50 V to allow the contact surface temperature of the stamper and the polymer substrate reaching glass transition temperature within 10 s for rapid embossing of microscale features. Since the graphene coating is very thin, the stamper surface could be cooled rapidly after embossing to keep the cycle time shorter than 25 s. This novel hot embossing technique was successfully implemented to imprint microchannel and microlens arrays on thermoplastic polymer substrates with high precision. Compared with conventional hot embossing, our facile method could achieve better replication fidelity with much less cycle time.