Ultralightweight Strain-Responsive 3D Graphene Network

In this study, we fabricated a three-dimensionally assembled architecture made of reduced graphene oxide (rGO) and utilized it as an ultralightweight strain gauge. Building units for the assembly were prepared over the multiscale starting from functionalized GO nanosheets at the nanoscale to microfluidically processed solid-shelled bubbles at the microscale. These GO solid bubbles were elaborately assembled into close-packed 3D structures over the centimeter scale and then reduced by thermal treatment. Thermally reduced rGO assembly of which the internal structure was spontaneously transformed into a closed-cellular structure such as the 3D rhombic dodecahedral honeycomb lattice during thermal reduction could manifest superior elasticity against a strain of 30% by virtue of the hierarchically interconnected network while securing a low density of about 10 mg/cm ³ and mechanical robustness, which was then applied as a strain gauge. The strain gauge with a thermally reduced 3D rGO structure exhibited a gauge factor of around 4 and excellent mechanical durability over 250 cycles, suggesting a new pathway for implementing ultralightweight strain-sensitive materials.