Breakthrough in laser technology shows promise for easing the lives of diabetics

Researchers at Princeton University have found a non-invasive method for monitoring blood glucose levels with a laser device.

A group of researchers at Princeton University (NJ, USA) have developed a method that uses a laser to measure people’s blood sugar levels, and this non-invasive method allows diabetics to avoid having to prick themselves every time they need to monitor their levels.

The device, as explained in a recently published article in the journal Biomedical Optics Express, operates by directing the specialized laser at a patient’s palm. The laser then passes into the body, without causing any harm, and becomes partially absorbed by the dermal interstitial fluid (the laser is not targeting the blood but the dermal interstitial fluid, which has a positive correlation with blood sugar levels), therefore allowing the researchers to use the amount of absorption to calculate the blood sugar levels.

The breakthrough technology that made the experiment possible was the infrared’s frequency. Most current medical devices use near-infrared (the highest frequency of infrared that is just below a human’s range of sight).

This frequency, although not blocked by water, is disturbed by the many acids and chemicals within the body, and is therefore redundant for monitoring blood sugar levels. Mid-infrared light is not affected by these acids and chemicals, so proves ideal for measuring blood glucose.

But mid-infrared light is difficult to harness with enough power and stability to penetrate the skin, so the real breakthrough was made with the use of a quantum cascade laser, which passes electrons through a ‘cascade’ of semi-conductor layers, with another advantage being that the beam can be set at different frequencies. Recent improvements allow the laser to deliver mid-infrared with enough power and stability to penetrate the skin.

The lead author, Sabbir Liakat, said the team was pleasantly surprised by the accuracy of the method, which is 84% accurate – glucose monitors are required to produce a blood-sugar reading within 20% of the patient’s actual level. For the experiment itself, the laser was used to read the levels of three healthy people before and after they each ate 20 jellybeans, which would raise blood sugar levels.

The researchers also recorded the measurements with a finger-prick test and conducted the process over the course of a few weeks. The results exposed average errors from the laser and, although less precise than the finger-prick system, it remained within the necessary requirement for accuracy.

The main researchers from Princeton University consisted of Sabbir Liakat, graduate student in electrical engineering; Claire Gmachl, the project’s senior researcher and the Eugene Higgins Professor of Electrical Engineering; undergraduate students majoring in electrical engineering, Kevin Bors, Laura Xu and Callie Woods; and Jessica Doyle, a teacher at Hunterdon Regional Central High School.

The scientists remain in high spirits, although there is a lot still to do with the shrinking down of the device to something more portable for the average user. The device is able to emit light across a very broad range of the spectrum, and shows potential for other medical sensing and monitoring applications.

Source: Laser device may end pricks, improve quality of life for diabetics.