Direct transfer of corrugated graphene sheets as stretchable electrodes

Abstract

The authors present the fabrication and characterization of corrugated graphene sheets on polydimethylsiloxane (PDMS) substrates for flexible and stretchable electrodes. The graphene sheets were grown on imprinted Cu foil via atmospheric pressure chemical vapor deposition. The grown graphene sheets with both corrugated and flat surfaces were then transferred from the Cu foil to PDMS substrates using a novel, direct transfer method, where PDMS was directly casted and cured on the graphene sheets followed by removal of Cu via wet etching. This process largely eliminated the formation of cracks in the graphene caused by traditional transfer processes. The corrugated graphene sheets were characterized using Raman spectroscopy and conductivity measurements under the application of lateral strain parallel and perpendicular to the graphene corrugation on the PDMS substrates, demonstrating a smaller shift of the two dimensional Raman peak for the corrugated graphene electrodes as compared to the flat graphene. It was shown that the maximum achievable strain prior to a change in electrode resistance increased from 8% for the flat graphene sheet to 15% for the corrugated graphene electrode. Preliminary results also showed that the corrugated graphene sheet maintained its material integrity and electrical conductivity under multiple cycles of high strains.