A multifunctional composite material with piezoresistivity and mechanoluminescence properties for a wearable sensor

Intelligent composite materials and devices are attracting a great interest owing to their potential impact on various future life applications. To meet the growing demand for multifunctional materials, the development and validation of visible sensing behavior is highly desirable, but the development of a single multifunctional wearable sensing material still remains a challenge to be achieved. To reach this goal, here we present a wearable intelligent fabric with piezoresistivity and mechanoluminescence ability based on a layer-structured graphene-based conductive cotton fabric and SrAl2O4:Eu2+, Dy3+/polyurethane foamed coating. The presence of the foamed coating structure endows the flexible composite fabric with a controllable positive/negative piezoresistivity (gauge factor from −2.5 to 17) and a bright mechanoluminescence ability that can be used in the darkness without additional batteries. Three-dimensional chromaticity diagrams have also been developed as advanced tools to quantitatively assess the luminescence, whose lightness, during the bending cycles, is highly repeatable with value in the range from ∼25 to ∼55. The multifunctional layered composite sensor provides multiple output signals which can be accurately recognized and assigned to independent triggering events, opening up new opportunities in advanced wearable devices based on commercial fabrics.