Facile and Scalable Fabrication of Hydrophilic/Hydrophobic Janus Fabric for Personal Sweat Monitoring and Perspiration Management

Abstract Quantifiable monitoring and management of sweat volume have attracted considerable attention because of their role in assessing physiological health and preventing dehydration. However, defective sweat monitoring and poor moisture management limit the performance of most smart textiles under moderate/profuse perspiration scenarios. In this study, a large‐scale fabrication technology is used, including braiding and weaving, to prepare a hydrophilic/hydrophobic Janus fabric (HHJF) with good directional water delivery and sweat‐volume monitoring capabilities. The HHJF consists of polytetrafluoroethylene (PTFE) braided yarns (lower layer) and Tencel braided yarns (upper layer), which comprise a conductive yarn as the core and PTFE/Tencel yarns as the sheath with enhanced water absorption capacity. The unique functional structure design achieves the enhanced unidirectional water transport and high sweat‐sensing response for the HHJF under perspiration conditions. The optimized HHJF facilitates spontaneous droplet penetration from the hydrophobic layer to the hydrophilic layer, while enabling the real‐time detection of sweat volume of up to 2000 mL m⁻² with excellent durability for over 1000 cycle tests. Thus, the exceptional perspiration management and monitoring capabilities of HHJF are expected to promote the development of practical smart textiles that enable real‐time monitoring of perspiration dynamics.