Braided Coaxial Two-Electrode Triboelectric Thread with a Mesh Spacer for Highly Sensitive Respiration Monitoring

Wearable medical devices play an increasingly important role in disease diagnosis and health management, and self-powered sensors based on the triboelectric principle provide new ideas for the development of wearable respiratory monitoring devices. To overcome the unstable shortage of reported triboelectric yarn with a single electrode and two freestanding electrodes, this work designed a coaxially braided triboelectric-sensing thread (CBTT) with a braided mesh spacer separating two-electrodes, which potentially meets the daily and long-term stable monitoring of human respiratory movements, and the effects of the braiding parameters of the mesh spacer on the performance of the CBTT were discussed. The results show that both the braiding process parameters of the mesh spacer and the specification of the mesh-braiding yarn affect the performance of the prepared CBTT. Among them, CBTT prepared by nylon monofilaments with a diameter of 0.2 mm and a 30° on-machine braiding angle had the best sensing performance under the designed strain range. In addition, for the respiratory state monitoring, the output response and the accuracy of CBTT with a mesh spacer are highest among three kinds of the studied sensing yarns with coaxially braiding structure. These results indicated the stable structure advantage of the seamless integration of a mesh spacer into the coaxially braiding two-electrodes triboelectric sensing yarn and brings new tools for user-friendly health monitoring.