Cellulose-reinforced natural rubber microfibers with low mechanical hysteresis for wireless physiological monitoring

Unprecedented demand for wearable electronics has stimulated the development of highly elastic strain sensors that monitor human motion. This study presents a highly stretchable, lightweight, and wearable strain sensor composed of natural rubber (NR) and cellulose nanofibers (CNF). It addresses the challenge of developing highly sensitive sensors with good linearity and low hysteresis for wireless physiological monitoring. By incorporating CNF as a reinforcing agent along with carbon nanotubes and PEDOT:PSS for conductivity, we have achieved significant improvements in sensor performance. The optimized wearable device exhibited an increase in fracture stress while maintaining high stretchability (over 600 %) with minimal hysteresis loss (approximately 2.7 % at 100 % strain), low response time (approximately 43 ms), and good mechanical durability. Furthermore, an integrated system based on the device was assembled to detect real-time fine wireless physiological signals generated from human motions, including walking, joint movements, and subtle finger bending. The ability of the system to wirelessly transmit data in real time enhances its potential for continuous health monitoring and human-machine interfaces as next-generation smart wearable electronics.