WASHINGTON - Chinese researchers have developed a device that uses near-infrared light to diagnose poor blood flow in a non-invasive way, which provides a tool for doctors to treat strokes more quickly.

The study, published on Tuesday in the AIP Advances, a journal of American Institute of Physics, reported the hybrid instrument relying on two near-infrared light techniques that can measure blood volume, blood oxygenation and blood flow rate.

Stroke, one of the leading causes of death worldwide, is normally caused by poor blood flow to the brain, and the condition must be diagnosed within the first few hours of the stroke for an effective treatment.

Researchers from Army Medical University in Chongqing and China Academy of Engineering Physics used the near-infrared "diffuse optical spectroscopy" to analyze light scattered from tissues in order to calculate the amount of oxygen and blood within an area.

Also, they used "diffuse correlation spectroscopy," another near-infrared light technique, to analyze fluctuations in tissue-scattered light to measure the rate of blood flow.

In an experiment, the researchers strapped the device probe to a participant's forearm, and then inflated an arm cuff around the subject's upper arm to block off blood circulation.

They found that the light reduced in intensity as the blood flow was cut off and brightened again when the arm cuff was removed, mirroring the changes in oxygen and blood in the forearm. Also, the blood was moving more slowly when the arm cuff was inflated, according to the study.

The device is cheap and compact since both techniques share the same detectors. The optical switch makes the combination of two light sources simple and the custom software makes measurement quick, according to the researchers.