A flexible strain sensor with three-dimensional microstructure using cellulosic Juncus effusus for monitoring human motions

Flexible strain sensors have attracted extensive research and applications in health monitoring and human-machine interaction owing to their exceptional flexibility and mechanical stability. Introducing micro-nano structures into sensor design represents a significant approach for enhancing sensing performance. Juncus effusus (JE) is a biomass resource rich in natural cellulose polysaccharide (carbohydrate polymer), whose intrinsic three-dimensional porous polysaccharide skeleton provides an ideal microstructure template for flexible sensing devices. This study utilized the internal 3D cellulose skeleton structure of JE fiber as a microstructural template of sensor. After being loaded with AgNPs and CNTs and encapsulated in an elastomer, the JE-based flexible strain sensor with effective real-time motion sensing capability was fabricated. The sensing performance tests indicated that the sensor maintained normal operation within tensile strain ranges of 5%-100% and bending angles of 30°–180°, and maintain stable monitoring performance through 2000 testing cycles, showing better overall sensing capability than conventional biomass strain sensors. Thus, the AgNPs/CNTs/Ecoflex-modified JE fibers based flexible strain sensor demonstrates reliable human motion detection capabilities.