A dam-inspired textile patch with layer-by-layer isovolumetric water transport for sweat loss monitoring

Abstract

Monitoring sweat loss is an effective method for evaluating dehydration during body thermoregulation. However, current wearable microfluidic sweat sensors often face limitations in terms of breathability and heat dissipation, and textile-based sweat sensors cannot achieve the accurate control and detection of sweat volume. Herein, we report a textile patch with an unprecedented layer-by-layer isovolumetric water transport (IVWT) ability for sweat loss monitoring. The patch features an all-porous laminated fabric with multiple IVWT units and conductive nonwoven fabric sensing units, enabling controllable and quantitative sweat penetration similar to dam-transporting ships. Each layer of the IVWT unit could accurately and stably transport 6.29 ± 0.10 μL of sweat across all tests. This design allows the identification of sweat volume by increasing stepwise jumps in the conductance signals. The dam-inspired textile patch not only provides sweat volume measurements that are highly consistent with those obtained using the absorbent pad method but also offers superior air permeability (~98% of the clothing), excellent heat dissipation (~79% of the uncovered skin), and excellent compatibility, which facilitates seamless integration into various types of wearable garments. A fully integrated wireless transmission device with the textile patch provided a validated predictive model for estimating whole-body sweat loss during dehydration monitoring.