Kyocera Corporation out of Kyoto, Japan has announced the development of a tiny optical sensor for measuring blood flow within subcutaneous tissue. Readings from such a device may help assess how injured tissue is healing, produce evidence of dehydration, and detect altitude sickness. Many other applications may come to light as this kind of technology becomes widely available for use by the public.
The sensor measures 1.6 mm by 3.2 mm and is only 1 mm in height. Because of its size it can be integrated into various devices, including smartphones and wearable activity trackers. Within the sensor is a laser that shines light onto the skin, and a photodiode that converts light returning from the skin into an electrical signal. By detecting and measuring the Doppler shift of the returning light compared to what the laser emits, the device can extrapolate how fast red blood cells are moving. Moreover, the strength of the light signal bouncing from the skin is indicative of the concentration of red blood cells, another interesting indicator.
The sensor at the moment only works on certain parts of the body where there’s a lot of blood perfusion close to the surface of the skin. This includes the ear lobe, fingers, and the forehead, and may include other parts of the body. It’s probably not very effective for using on the bottom of feet for people at risk of diabetic neuropathy, for example.