Skin-Based Sweat Monitoring Using Radio Frequency Identification Sensors
Klinker, Lauren E.
- Wearable sensors are a current trend in personalized healthcare that enable individuals to monitor physiological variables in real-time and without interruption of daily activity. This technology could be beneficial in ensuring the health and performance of athletes, who are at high risk for dehydration due to increased fluid losses through the sweat during training and competition. Even at low le... read morevels, dehydration causes excess stress to the cardiovascular system and impairs both physical and cognitive performance. Current methods for monitoring hydration include urine analysis, plasma osmolality, and body mass tracking, yet these methods are limited in their ability to provide information on water and electrolyte losses with instant feedback accessible during activity. This project focuses on the development a wearable device to monitor local sweat losses from the surface of the skin in real-time using a radio frequency identification (RFID) sensor to wirelessly transmit information to a nearby reader. A skin patch for sweat collection was designed by testing the absorption and moisture transmission properties of absorbent cellulose pads and selecting a material to match expected sweat rates without altering secretion from the glands. Subsequently, a passive RFID tag was integrated with the proposed skin patch and the tag antenna was interrogated with a reader during fluid absorption. As conductive fluid accumulated within the patch, an increase in the tag capacitance due to the high dielectric properties of water caused a steady decrease in the center frequency of the reflective power losses. These results demonstrate the ability to detect the volume of conductive fluid collected within an absorbent patch, which could be used to measure the local sweat rate with wireless feedback in real-time. This information could be used to guide fluid and electrolyte replacement to prevent dehydration and maximize athletic performance.read less