Design of Porous Graphene/ PDMS Composites With Optimized Electrical and Mechanical Properties for Flexible Sensors

ABSTRACT Porous graphene (GNP)/polydimethylsiloxane (PDMS) composites, known for excellent elasticity, tunable mechanical properties, and high flexibility, have emerged as ideal candidates for high‐performance flexible sensor applications. However, conventional pore‐forming techniques often result in irregular pore structures, which can cause stress concentrations and compromise the material's stability and sensing performance. In this study, porous GNP/PDMS composites with spherical pore structures for flexible sensor were successfully prepared using expanded polystyrene (EPS) as a sacrificial template via the vacuum infiltration method. A multi‐step ultrasonic dispersion process was employed to optimize the dispersion of graphene within the PDMS matrix, and the electrical conductivity, mechanical properties, and sensitivity of the resulting GNP/PDMS composites were systematically characterized. The composite containing 4 wt.% graphene exhibited excellent performance, with high electrical conductivity of 2.17 × 10 ⁻³ S/m, an elastic modulus of 2.4 MPa, a maximum tensile strength of 1.5 MPa, and outstanding gauge factor of 65 at 5% strain. Furthermore, porous GNP/PDMS composites and their packaged sensors were subsequently fabricated. The porous composites maintained over 99.6% recovery after 200 compression cycles, demonstrating excellent mechanical resilience. Sensors based on these porous composites showed superior strain response under tension, compression, and finger joint bending, with high sensitivity and the ability to accurately distinguish between different types of motion.