关键词:
Sensors
Monitoring
Dielectrics
Statistics
Sociology
Fabrics
Electronic healthcare
Antenna-based sensor
eHealth
low-cost
radio-frequency identification (RFID)
摘要:
Health monitoring during physical exercise is relevant to avoid issues like dehydration, especially for vulnerable populations or in warm climates, since it may become critical in these cases. Current dehydration monitoring solutions are not intended for the general population, since they are expensive or require the action of wearing the device. Hence, a cost-efficient monitoring technology that could be integrated into everyday clothing would allow the democratization of eHealth, thus improving the health of the general population. We have been researching low-cost sensing technologies, allowing the detection of dehydration, while maximizing the tradeoff between functionality and cost. In this article, we present a passive antenna-based ultrahigh-frequency (UHF) radio-frequency identification (RFID) sensor, allowing noninvasive dehydration monitoring on fabrics at low cost. We determine that the dielectric relative permittivity (epsilon '(r )) and loss tangent ( tan(delta) ) values exhibit a change up to 10 and 0.3, respectively, in the presence of euhydrated (i.e., regular hydration) and dehydrated sweat in the UHF band. We use these results to design a UHF RFID tag attached to a fabric, capable of differentiating between these hydration states. After prototype implementation, we demonstrated good classification metrics in a laboratory environment, reaching a 100% accuracy using K-means unsupervised learning when attempting to differentiate between euhydrated and dehydrated sweat in fabrics with concentrations over 58%. To the best of our knowledge, this combination of results is presented for the first time in the literature. Our results demonstrate the feasibility of detecting dehydration at low cost in an unassisted manner, and thus, the possibility of democratizing eHealth for the general population.