Graphene: Diversified Flexible 2D Material for Wearable Vital Signs Monitoring

Flexible wearable sensors are expected to be the future generation of personal health monitoring devices with large-area, multimodal, multipoint sensing, and complicated data analysis. However, multimaterial interfacial coalescence and mechanical matching critically challenge the advancement of flexible devices and multifunction integration. Graphene, with characteristic carbon sheet 2D material, is endowed with good transparency, stability, superior electron mobility, heat conductivity, excellent flexibility, and mechanical performance. A summary of the progresses of flexible graphene-based sensors in terms of material processing, sensor configuration, and property is presented. Various assembly structures could perform different electrical behaviors with unitary graphene material. The diversity of graphene-based temperature, humidity, pressure, strain, and integrated multifunctional sensors developed in recent years is detailed. Benefitting from the commendable flexible mechanical performance and high durability, flexible graphene-based sensors promote practical applications in body temperature monitoring, voice recognition, pulse-beating, motion, and respiration detection. Finally, future research following the development trends and challenges of integrated graphene-based sensors to develop their potential in human health monitoring and human-machine interfaces are discussed.