An optical sensor for measuring blood-flow (1 mm high, 1.6 mm long, and 3.2 mm wide), has been developed by Kyocera Corporation of Japan.

The company is investigating mobile health applications for the device, which can include monitoring stress levels or preventing dehydration, heatstroke, and altitude sickness, all of which can be indicated by changes in blood-flow volume.

The integrated module, featuring a high signal-to-noise ratio and low power consumption of 0.5mW, incorporates a laser diode and photodiode into a single ceramic package. Blood-flow volume in subcutaneous tissue can be measured by placing a sensor-equipped device in contact with an ear, finger, or forehead.

When light is reflected on blood within a blood vessel, the frequency of light varies — called a frequency or Doppler shift — according to the blood-flow velocity. The sensor uses the relative shift in frequency, which increases as blood flow accelerates, and the strength of the reflected light, which grows stronger when reflected off a greater volume of red blood cells, to measure blood-flow volume.

Kyocera plans to offer samples of the sensor module in April 2017, and aims for full device commercialization by March 2018.

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