Harmonious state between filled and coated flexible conductive films: An ultra-high conductivity, sensitive and environmentally stable sensing film based on integrated layered structure

There is an urgent need for the development of high-performance and particularly environmentally stable strain sensors to address the requirements of wearable health monitoring for the real environment. However, despite considerable efforts, few classes of conductive elastomers have so far been able to fully satisfy the above requirements. Inspired by the multiple layers of human skin, herein we design an amazing integrated layered structure based on carboxylated styrene butadiene rubber/regenerated sodium lignosulfonate-silver nanowires (XSBR/rSL-AgNWs), including an ultra-high conductivity AgNWs-enriched layer of 500 S/m at loads as low as 5 wt%, an rSL segregated network layer providing a tensile strength 10.2 MPa, and a compact rubber layer with water-resistant property. With such a distinctive integrated layered structure, the film earns an impressive stable conductivity in water with a small amount of filler, a high sensitivity of 110 ms, gauge factor of 145.8 and wide response strain range from 0.5% to 350%. These excellent sensing properties enable the composite film to monitor motion, pulse, and voice signals in complex environments, thus offering a new avenue for the development of flexible electronic devices.