Ultralight Interconnected Graphene-Amorphous Carbon Hierarchical Foam with Mechanical Resiliency for High Sensitivity and Durable Strain Sensors

Ultralight graphene-amorphous carbon (AC) hierarchical foam (G-ACHF) was synthesized by chemical vapor deposition at 1065 °C, close to the melting point of copper. The high temperature leads to the hierarchical structure with an inner layer of graphene and an outer layer of AC. The inner graphene layer with high conductivity and integrity provides high sensitivity. The outer AC layer helps to enhance its durability and mechanical resiliency. The hierarchical structure recovers without damaging the structural integrity after a large strain of 90%. The electrical resistance of G-ACHF remains stable after 200 cycles of compression to a strain level of 50%. The fluctuation of the resistance value remains within ±3%, showing its stability in sensing performance. The pressure sensitivity of G-ACHF reaches as high as ∼11.47 Pa^-1. Finite element simulation reveals that the stress borne by the key position of G-ACHF is 47% lower than that of graphene foam without the AC layer, proving that the AC layer can disperse the stress effectively. With a very low density of 1.17 × 10^-3 g cm^-1, the reversibly compressible G-ACHF strain sensor material exhibits its promising application potential in lightweight and wearable devices.