Reduced graphene oxide aerogel/polydimethylsiloxane biphasic composite with “button - like” interpenetrating dual - network structure for ultra - high and ultra - broad tunable sensitivity strain sensor

Abstract

With the growing demand for wearable electronics, flexible strain sensors with wide sensing ranges and high sensitivity have become a key research focus in recent years. However, the performance of carbon material/polydimethylsiloxane (PDMS) composites is often hindered by poor dispersion of carbon materials and limited compatibility between conductive carbon networks and PDMS networks. Here, we present a manufacturing process and formulation for ultra-high and ultra-broad tunable sensitivity strain sensor based on a biphasic composite composed of reduced graphene oxide aerogel (rGA) and PDMS. The innovation lies in preparing an ice and bubble template-based reduced graphene oxide aerogel (IBrGA) with large pores (50–1200 μm), which achieved excellent conductivity (~ 8.9016 S/m) with minimal filler content (~ 0.492 wt%). Additionally, a “button-like” interpenetrating dual-network structure was formed by modifying the conductive phase IBrGA with silane coupling agent KH - 151 and the insulating phase PDMS with vinyl-terminated methyl silicone resin (VMQ) and high-viscosity vinyl - terminated PDMS (VtPDMS2000). This interpenetrating dual - network structure enabled the flexible wearable strain sensor, based on the biphasic composite (K₅@IBrGA/PDMS), to achieve ultra - high sensitivity (GF up to ~1792.78) without significantly sacrificing the sensing range. The sensor's sensitivity could be finely tuned by adjusting the mass ratio of VtPDMS500 to VtPDMS2000, with a GF range from 3.29 to 1792.78. It could detect strains as small as 0.1 % and showed excellent resistance response stability. This exceptional performance makes it a promising candidate for flexible strain sensors with different sensitivity requirements applications such as wearable devices, robots, and medical monitoring.