Soon biometric watch that uses light to monitor glucose, dehydration, pulse

Researchers from the Netherlands and Israel have described two new wearable devices that use changing patterns of scattered light to monitor biometrics: one tracks glucose concentration and dehydration levels, and the other monitors pulse.

The glucose sensor is the first wearable device that can measure glucose concentration directly but noninvasively, the authors say.

And while other wearable devices have been made to monitor pulse, the authors claim their new design would be less sensitive to errors when the wearer is in motion, for example while walking or playing sports.

Both of the watches described in the two papers make use of the so-called "speckle" effect, the grainy interference patterns that are produced on images when laser light reflects from an uneven surface or scatters from an opaque material.

When the material that is scattering the light is moving—say, in the case of blood flowing through the circulatory system—"the speckle pattern changes with changes in the flow," explained biomedical engineer Mahsa Nemati, a graduate student in the Optics Research Group at the Delft University of Technology in the Netherlands and the lead author of the Biomedical Optics Express paper on monitoring pulse. Those light variations are a valuable source of information, she says.

The papers have been published in The Optical Society's (OSA) open-access journal Biomedical Optics Express.