Mobile microplasma synthesis of silver nanoparticles/graphene nanocomposites for flexible strain sensors

Abstract

A mobile microplasma jet was used for the direct, reductant-free, and controlled synthesis of silver/graphene nanocomposites. These nanocomposites were integrated with polydimethylsiloxane to construct flexible strain sensors. The correlation between AgNP content and sensor performance was systematically investigated. The Ag/Gr-16.9% sample exhibited high sensitivity and excellent durability, showing an overall stable ΔR/R₀ under 800 stretching cycles at 200% strain (10 mm s⁻¹) with only a slight decline. The sensor enabled reliable motion monitoring, including finger bending with a relative resistance change of ∼500%, and knee bending/extension at 15°, 30°, 45°, 60°, and 75° with ΔR/R₀ changes of ∼470%, 870%, 890%, 1000%, and 980%, respectively. These results highlight the sensor's capacity to track joint kinematics and bone-related mechanical loading. This work demonstrates a green and transfer-free route for in situ fabrication of Ag/Gr nanocomposites, providing guidance for constructing high-performance flexible strain sensors tailored for human motion monitoring and orthopedic diagnostic applications.