Facile fabrication of highly sensitive and durable cotton fabric-based pressure sensors for motion and pulse monitoring

Abstract

Design and development of flexible pressure sensors with high sensitivity, long-term stability and simple fabrication processes is a key procedure to fulfill the applications in wearable electronics, e-skin, medical monitoring, etc. Here, we present a highly sensitive, durable, cotton fabric-based pressure sensor by a simple cyclic dipping–drying approach of graphene dispersion. Gelatin, as a dispersant and stabilizer, is used for preparing graphene nanosheet (GN) dispersions. Strong interactions including hydrogen bonds and hydrophobic interactions firmly immobilized GNs on the surface of cotton fibers mediated by gelatin. Benefiting from the uniformly immobilized GNs and the interweaved microstructures of cotton fabrics, the resulting graphene/gelatin functionalized pressure sensor (GGFPS) exhibited low resistivity (34 Ω cm), a wide linear detection range (2.51–6800 Pa), fast response (60 ms), low hysteresis (degree of hysteresis: 3.06%) and excellent cyclic working stability (3000 cycles). The electrical properties remained almost the same after 10 cycles of washing in SDS aqueous solution, revealing good washing durability. The GGFPS also possessed increased tensile strength compared with pristine cotton fabrics. Furthermore, this flexible cotton fabric-based pressure sensor could sense various human motions and physiological signals such as finger bending, wrist movement and swallowing. Importantly, the GGFPS could monitor the pulse signals of jugular veins and wrist arteries in real-time. Thus, this work indicates the great application prospect of this pressure sensor in wearable electronics, flexible circuits, and medical diagnosis.