A Wearable Sweat Rate Sensor with Adaptive Sweat Ion Concentration Calibration

Wearable sensors for continuous physiological biomarker monitoring offer a non-invasive and personalized approach to healthcare. Sweat, as a readily accessible biofluid, serves as a valuable medium for biomarker detection. However, accurate biomarker analysis relies on precise sweat rate measurements, as sweat concentration and secretion rates are interdependent. To address this, it is critical to calibrate sweat ion concentration to enhance the accuracy of sweat rate monitoring. Moreover, the distribution of sweat glands varies across different body regions, necessitating application-specific design modifications for wearable sweat rate sensors. Effective sensor implementation requires adaptability in design while ensuring compatibility with scalable fabrication techniques. In this work, we present a digital fabrication method that allows for easy customization and large-area manufacturability. A key advancement in our approach is the integration of secondary capacitive sensing to continuously monitor sweat ion concentration, which is incorporated into real-time sweat rate calculations. This calibration technique enhances measurement precision by accounting for fluctuations in sweat composition. Additionally, we developed customized readout electronics and a mobile application for real-time sweat rate visualization, enhancing user accessibility and convenience. By incorporating sweat ion concentration calibration through capacitive sensing, our sensor system significantly improves the accuracy and reliability of sweat rate measurements, advancing real-time perspiration monitoring for personalized health applications.