Smart Textile Systems as Dynamic Platform for Human Hydration Monitoring

Abstract Wearable sweat sensing technologies have emerged as a promising non-invasive approach for continuous assessment of human hydration status. Among various wearable platforms, textile-based systems provide unique advantages including breathability, mechanical compliance, and seamless integration into garments, enabling long-term physiological monitoring during daily activities and athletic performance. This review provides a comprehensive overview of textile-based wearable sweat sensors for human hydration assessment. First, key biochemical indicators of hydration, including sweat electrolytes and sweat rate and their physiological correlations are discussed. The fundamental sensing mechanisms for ion detection and sweat-rate monitoring are then summarized, with emphasis on electrochemical and electrical sensing approaches compatible with textile integration. Recent advances in textile substrates, in-textile electrodes, and functional materials, including metals, carbon materials, conductive polymers, and emerging two-dimensional nanomaterials, are critically reviewed. Fabrication strategies are further examined from both direct deposition and fiber-level integration perspectives, alongside advanced sweat collection approaches such as textile microfluidics and Janus structures that enable controlled and directional fluid transport. Finally, current challenges and future research directions are discussed, focusing on system integration, long-term stability, standardized validation, and clinical translation. This review outlines the pathway toward next-generation smart textile platforms capable of reliable and real-world hydration monitoring.