| abstract |
An improved sensor ( 102 ) for hydration monitoring in mobile devices, wearables, security, illumination, photography, and other devices and systems uses an optional phosphor-coated broadband white LED ( 103 ) to produce broadband light ( 114 ), which is then transmitted along with any ambient light to target ( 125 ) such as the ear, face, or wrist of a living subject. Some of the scattered light returning from the target to detector ( 141 ) is passed through a narrowband spectral filter set ( 155 ) to produce multiple detector regions, each sensitive to a different waveband wavelength range, and the detected light is spectrally analyzed to determine a measure of hydration, such as fluid losses, fluid ingested, fluid balance, or rate of fluid loss, in part based on a noninvasive measure of components of the bloodstream. In one example, variations in components of the bloodstream over time such as hemoglobin and water are determined based on the detected light, and the measure of hydration is then determined based on the in components of the bloodstream over time. In the absence of the LED light, ambient light may be sufficient illumination for analysis. The same sensor can provide identifying features of type or status of a tissue target, such as heart rate or heart rate variability, respiratory status, or even confirmation that the tissue is alive. Hydration monitoring systems incorporating the sensor, as well as methods, are also disclosed. |