Abstract:

Objective This study focuses on the preparation of flexible force-sensing electronic textiles and the development of a human motion monitoring system. The objective is to provide a better method to monitor and analyze health physiological information, and to generate health indications.

Method The intelligent electronic fabric used in this study employed piezoresistive sensing as its underlying principle. Its structure followed a "sandwich″ design, consisting of a conductive layer and two electrode layers. The upper and lower electrode layers, made of cotton yarns and silver-plated yarns, were intricately laminated with a 1/1 plain woven conductive fabric and sewn together. The intermediate conductive layer is achieved by modifying woven cotton fabric with a combined solution of graphene and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄), resulting in a conductive fabric.

Results The output-input characteristic curve of the fabric sensor exhibited clear piecewise linearity, with the slope of the curve decreasing as pressure increases within the pressure range of 0 to 140 kPa. Notably, high sensitivity was observed in the pressure range of 0 to 5 kPa (S₁=0.15 kPa^-1), followed by a decrease in sensitivity in the pressure range of 6 to 15 kPa (S₂=0.07 kPa^-1), and a decrease in sensitivity in the pressure range of 16 to 40 kPa (S₃=0.01 kPa^-1). The sensor demonstrated a fast response time of 20 ms/30 ms and minimal hysteresis error, respectively, during the compression and release processes, enabling real-time capture of human dynamic motion signals. The flexible electronic fabric exhibited stable resistance even after 8 000 cycles of pressure application, demonstrating good mechanical durability, as seen. It was also less affected by washing, as observed from the resistance change curve after washing soaking. The fabric possessed suitable breathability, effectively dissipating body heat and maintaining a refreshing skin surface. Additionally, the thermal and wet comfort requirements were met with a measured moisture permeability of 6.4×10³ g/(m²·24 h).

Conclusion Through the design of a composite structure, a flexible piezoresistive pressure sensing electronic fabric with a "sandwich″ structure has been successfully developed. This innovative fabric incorporates a sensing array, enabling real-time collection of pressure levels and distribution across different parts of the body. Comprehensive testing has demonstrated that the electronic fabric exhibits remarkable sensing performance and wearing comfort. The results indicate that the fabric possesses high sensitivity (approximately 0.15 kPa^-1 within the pressure range of 0-5 kPa), fast response time, minimal hysteresis, excellent repeatability, and favorable thermal and wet comfort properties. Furthermore, by integrating the pressure sensing electronic fabric with self-designed electric circuits and computer software, an intelligent electronic fabric pressure distribution monitoring system has been realized. This system generates pressure mapping maps with uniform appearance and high resolution, thereby validating the reliability of intelligent electronic fabrics in monitoring human motion signals. The potential applications of this technology are vast, encompassing healthcare and sports, and it holds great promise for the future in various fields.

Key words: textile-based pressure sensor, intelligent electronic textile, sensing performance, graphene, intelligent pressure distribution monitoring system