No More Pin Pricks To Test Blood Sugar

Blood sugar tests as of today are slightly invasive procedures, which involve pricking one’s finger to check blood glucose levels. In order to avoid this pain in times to come, a team of electrical engineers, from New Jersey’s Princeton University, is currently working on a non-invasive method that uses laser technology to measure blood glucose. Though the day that a portable laser device will replace existing method for blood glucose testing seems like a way off, researchers believe that the replacement theory is imminent.

The team has shared its findings in the journal Biomedical Optics Express about how their prototype device was used to measure blood sugar by directing the laser at a person's palm.

Claire Gmach, senior author of the study and the Eugene Higgins professor of Electrical Engineering at Princeton, says that the team plans to improve the lives those people who are suffering from diabetes and depending on frequent blood glucose monitoring.

Skin is penetrated by the laser which is absorbed by glucose

This portable device sends a laser beam through the skin cells without any damage, which is then absorbed by sugar molecules. The focus shifts from blood sugar to the sugar content of dermal interstitial fluid, which is known to have a stronger correlation with blood sugar. The amount of glucose in the blood is indicated by how much the laser beam is absorbed.

Most commonly used glucose monitors are required to show readings within 20% of the patient's actual blood level. According to lead author Sabbir Liakat, a graduate student in Electrical Engineering, while the early version of the laser system met this requirement, the latest version showcases 84% accuracy. The team is now focusing on improving the technology.

Early version of the device

Early models of the device required an elaborate system to keep it cool and spanned an average lab bench. While the cooling problem is said to have been solved and the device is now capable of running at room temperature as well, Gmachl stated that researchers need to work more in a bid to make the technology more compact.

The researchers’ ultimately aim is to develop a mobile device that they will be able to carry to clinics in order to conduct further testing on, so that they may collect a larger set of data to work with.

Mid-infrared light produced by 'quantum cascade laser'

An infrared laser light is used by the system, which is just beyond the spectrum light that the human eye is capable to see. Currently, most medical devices make use of near-infrared. This is a band that has slightly longer wavelengths than the red that is visible to the human eye. Since near infrared isn’t blocked by water, it can be used in the body. The problem though is that near infrared does not react with chemicals in the skin. To produce that effect, one has to use slightly longer wavelengths in the mid-infrared region. The laser light at this wavelength is not affected much by other chemicals in the skin and is absorbed by blood sugar.

It is more difficult to harness mid-infrared laser light with standard lasers. For the beam to be able to penetrate the skin and scatter off bodily fluid, it needs higher power and stability.

Then, researchers chanced upon a breakthrough in their study and tried a new type of device called a 'quantum cascade laser.' With the help of this quantum cascade laser, the team was able to choose the frequency they needed in the mid-infrared region. This laser also provides the increased stability and power required to penetrate the skin, owing to recent improvements in the technology.

Average readings meet required clinical accuracy, study reveals

The researchers have described in their study, how they measured the blood sugar of three healthy individuals before and after each of them consumed 20 jellybeans. The resulting rise in blood sugar was also measured by the researchers using the conventional finger-prick test.

The experiment was repeated and measurements were taken over the span of several weeks. According to the results, despite the average readings of the laser device having more significant errors than standard blood sugar monitors, these readings were still within the range required for clinical accuracy.

This discovery is an exciting proposition in the medical world. Gmachl explains that at some point in the future, the quantum cascade laser may be designed to go beyond glucose detection. Due to its ability to emit light across a very wide wavelength range, this laser could conceivably be used for other medical sensing and monitoring applications, the professor added.

The study was funded by the Wendy and Eric Schmidt Foundation, the National Science Foundation, Opto-Knowledge Systems and Daylight Solutions Inc.
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