A sunlight self-healable fibrous flexible pressure sensor based on electrically conductive composite wool yarns

The present work proposed a simple approach for producing a fibrous flexible resistive-type pressure sensor from wool. By dip-coating polyurethane (PU) and silver nanowires (AgNWs) onto wool yarn, the latter was turned into a coaxial cable-like structure with the electrically conductive AgNWs/PU composite sheath for the sensing functionality and the wool core for providing a pliable substrate of the sensor. Afterward, the overlapping region of two strands of orthogonally stacked conductive composite yarns was employed to act as the pressure sensor. The experimental results indicated that conductivity and durability of the conductive yarn and sensitivity of the pressure sensor are closely correlated and can be effectively tuned through changing the amounts of PU and AgNWs. The surface fine structure of the composite yarns is a key factor determining responsive behavior. As a result of optimization, the pressure sensor has acquired high sensitivity and long-term working stability. Moreover, the homemade PU imparted the sensor with sunlight triggered self-healability of micro-cracks. It is anticipated that the pressure sensor possesses promising application potential in a variety of areas, including wearable electronics and e-textiles.