A wearable physiological hydration monitoring wristband through multi-path non-contact dielectric spectroscopy in the microwave range

Maintaining good physiological hydration is critical and can have marked effects on health and performance. Yet no reliable, simple, and widely-accepted method for hydration assessment exists. Even in clinical settings current methods are based on a series of empirical symptomatic observations, and though various candidate quantitative methods have been trialed, none has proven reliable or simple enough to become widely-accepted for either medical or lifestyle applications. A new type of wearable wristband device is detailed, simulated, and tested. This new monitoring mechanism tracks minute changes in the hydration of the wrist, which is used as a representative peripheral anatomical volume for tracking changes in hydration status. Measurement is made through a multi-path non-contact dielectric spectroscopy approach in the 2-6 GHz range. Numerical measurement methods based on multi-path broad spectral attenuation averaging, and principal component analysis are explored. A prototype of the design is constructed and programmed, and preliminary measurements from this device are shown to achieve a good correlation to cross section of the forearm, while being insensitive to alignment variations that are typical of a wearable wristband.