Soft, skin-interfaced, wearable biosensors for athletic sweat analytics and real-time dehydration monitoring

Dehydration during exercise degrades performance and increases heat-related risk; however, the commonly used gold-standard measurements like body-mass change and urine/blood analysis are not compatible with continuous, in-field monitoring. In this paper, we present a soft, skin-interfaced, wearable biosensor for athletic sweat analytics and real-time, continuous dehydration monitoring, measuring electrocardiograms, temperature, heart rate, and motion. In controlled running protocols, the wearable device captures continuous sweat osmolality dynamics, expected increases in heart rate and temperature, and partial recovery after water intake. Intermittent saliva osmolality measurements obtained with a commercial device show consistent pre-/post-rehydration tendencies but lack resolution for continuous changes. Field evaluation with collegiate football athletes demonstrates our device's long-term operation and reveals individual variability in dehydration changes and rehydration periodicity. These findings support the wearable biosensor suite as a multimodal athletic health-monitoring platform for continuous dehydration monitoring and assessment of physiological status in real-world exercise settings.