Eco-friendly fabrication of flexible graphene coated piezoresistive foams for motion sensing

The progress of flexible materials processing technologies has been remarkable, driven by the growing demand for flexible, ultra-sensitive wearable sensors in applications such as myoelectric prosthetics, soft robotics, and personalized health tracking. Conductive materials coated Polydimethylsiloxane (PDMS) sponges were utilized as piezoresistive sensors. A lightweight graphene-coated piezoresistive sensor was prepared via a green solution containing graphene nanoplatelets (GNP), sodium dodecyl benzene sulfonate (SDBS), and polyvinyl alcohol (PVA). The sponges with seven times coating revealed a resistance of below 100 kΩ at 80% strain, which indicated their sensing ability. The sensor output linearly increased as the strain raised, which was analyzed using linear regression to find the gauge factor of 1.387. A cyclic test was conducted on the foam-based piezoresistive sensor, demonstrating a stable response. The prepared conductive PDMS foam was tested on three main body joints (i.e. finger, knee, and, foot) at different angles and could detect mechanical action, indicating its potential use as a body-mounted strain sensor.