Highly Stretchable and Conductive Carbon Thread Incorporated into Elastic Rubber for Wearable Real-Time Monitoring of Sweat During Stretching Exercise

Wearable sweat sensors with excellent stretchability and sensing performance attracted significant attention in the real-time monitoring of physiological data on human sweat. However, most stretchable sweat sensors suffer from low sensitivity at high strains, and the fabrication methods are complicated and time-consuming. In this study, a highly stretchable sensor by incorporating carbon thread into an elastomeric substrate using a 3D-printed mold based on a wave pattern in an efficient and easy process is developed. As target biomarkers, sodium ion detecting electrochemical sensors are investigated, and these sensors exhibited high sensing performance of sensitivity, repeatability, selectivity, and stability. In particular, the sensor exhibited highly stable sensing performances even under a high strain of 300% and during a fatigue test of 10 000 stretching and releasing cycles at 300% strain. The real-time monitoring performance of the stretchable sensor integrated with a wireless electronic module is further demonstrated by conducting on-body tests of the subject's different physical activities of regular cycling, combined seated rowing and cycling, and treadmill running exercises.