Self-Encapsulated Breathable Reduced Oxide Graphene-Coated Melamine Foam for Stress Sensing

Three-dimensional graphene foam (GF)-based flexible piezoresistive sensors have the advantages of high conductivity, large deformable range and light weight, which has been utilized in human health measurement, electronic skin, and wearable devices. However, the encapsulation and electrode connections of such sensors reduce breathability, resulting in discomfort and even skin irritation. In this study, a self-encapsulated breathable GF (SEB–rGO–MF) and an SEB–rGO–MF-based piezoresistive sensor (SEB–rGO–MF–PS) are proposed. The SEB–rGO–MF–PS consists of a SEB–rGO–MF and two electrodes, ensuring encapsulation and electrical connection without compromising breathability and stability. We performed material characterization and breathability tests of the SEB–rGO–MF and investigated the sensing mechanism of the SEB–rGO–MF–PS. The SEB–rGO–MF–PS exhibits a sensitivity of 0.108 Pa–1, a measurement range of 0.013–15 kPa, rapid response/recovery times (83 and 166 ms), and excellent stability (2000 cycles at 15 kPa). In addition, this study demonstrates the application of the SEB–rGO–MF–PS for human motion monitoring.