Measuring blood sugar with laser beams

No more needles? Scientists use 2 beams of infrared light to figure out the glucose concentration in blood. The noninvasive method could mean monitoring patients continually.

No more needles and pricked fingers… now lasers can be used to gauge the glucose levels in diabetics.

Well, so for this gentler technique has only been tried with sugar water and blood serum, but if it works in humans, the device could be used in hospitals and homes to monitor patients continuously. Science News reports.

It’s been a decades-old dream of scientists to use beams of near-infrared light to measure glucose levels in the body. “Having a noninvasive way to measure glucose has long been a holy grail for our community,” says study author Andreas Mandelis at the University of Toronto.

As the light passes through human tissue harmlessly, it vibrates chemical bonds in the sugar molecule, absorbing energy. This absorption is measured, providing info about the concentration of glucose in the blood.

The trick is to make sure other things in the blood aren't also absorbing the near-infrared. That’s where scientists have been tripped up so far.

So Mandelis and his team used mid-infrared light, which is absorbed by glucose and not by other molecules in the blood, but with one major exception: water, which makes up most of blood’s volume.

They used 2 beams that are tuned to slightly different wavelengths:

One is absorbed by both water and glucose, the other by only water. When both beams strike dissolved glucose in concert, the water absorptions cancel each other out, giving off measurable heat that spotlights just the sugar.

So far, it’s proven sensitive even to small quantities of glucose. And the team is working with a Toronto hospital to set up tests with people.

The work will be published in a forthcoming issue of Physical Review E.

Via Science News.

Image by J. Fang

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