No more prick tests? Diabetes development

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  • Published: Sep 1, 2014
  • Channels: Infrared Spectroscopy
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Fair to middling

Noninvasive in vivo glucose sensing on human  subjects using mid-infrared light Graphic montage by David Bradley

Researchers in the USA have developed a way to use mid-infrared quantum cascade laser spectroscopy to measure blood glucose through one's skin. If they can successfully miniaturise the system it could be a boon for people with diabetes who otherwise have to regularly prick their skin to obtain a blood sample for testing.

Scientists from Princeton University, New Jersey, and a team of undergraduate students have turned to the mid-infrared laser to help them measure blood sugar without the need to spill a drop of blood. In a quantum cascade laser, electrons pass through a "cascade" of semiconductor layers and the beam can be set to one of a number of different frequencies allowing the researchers to generate a pulse in the mid-infrared region. In this region, the laser can penetrate skin but is unaffected by water, acids and other chemicals in the skin.

Lighten up

"We are working hard to turn engineering solutions into useful tools for people to use in their daily lives," explains electrical engineering professor Claire Gmachl project leader. "With this work we hope to improve the lives of many diabetes sufferers who depend on frequent blood glucose monitoring."

Writing in the journal Biomedical Optics Express recently, the team explains how laser light in this region of the IR spectrum passes through the skin on a person's palm but is partially absorbed by the sugar molecules in the dermal interstitial fluid. Initially, the absorption pattern is correlated with concentration in this fluid, which is a proxy for blood glucose concentration to give them a reading that is useful in healthcare for diabetes, and other, patients.

If you want blood...

Lead author on the paper, Sabbir Liakat, says the team was pleasantly surprised at the accuracy of the method. Current home glucose monitors that need a drop of blood, give a reading that is within 20 percent of the actual concentration that might be measured by an analytical laboratory; this is adequate for a patient to dose themselves appropriately with insulin. The prototype of the Princeton laser system falls well within that tolerance. "Throughout a glucose concentration range of 80 to 160 milligrams per deciliter, we achieve clinically accurate predictions 84% of the time on average," the team reports. The system was tested with three volunteers initially. Liakat adds that, "It works now but we are still trying to improve it." Initially, the setup filled a moderate-sized workbench and had an elaborate cooling system to keep it running. Gmachl says the team has solved the cooling problem so that the laser works at room temperature, the next step is to reduce the overall size of the instrumentation to make it portable so that it can be tested in the clinic.

"Because the quantum cascade laser can be designed to emit light across a very wide wavelength range, its usability is not just for glucose detection, but could conceivably be used for other medical sensing and monitoring applications," Gmachl adds.

Related Links

Biomed Optics Express, 2014, online: "Noninvasive in vivo glucose sensing on human  subjects using mid-infrared light"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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