Photoacoustic spectroscopy takes sting out of glucose testing

A noninvasive method involving mid-IR photoacoustic spectroscopy (PAS) could make life easier for the more than 347 million people worldwide who live with diabetes.

One key to healthful living with type 1 and type 2 diabetes is monitoring blood glucose levels to ensure they remain stable. People can easily and reliably do this at home using electronic devices that read sugar levels in a tiny drop of blood, obtained with a pinprick.

Finger-stick blood glucose monitoring could be a thing of the past, thanks to a new method involving photoacoustic spectroscopy.

The new method, developed at Johann Wolfgang Goethe University, negates the need for the needle. Using IR laser light applied on top of the skin, the researchers measured sugar levels in the fluid in and under skin cells to read blood sugar levels.

“This opens the fantastic possibility that diabetes patients might be able to measure their glucose level without pricking and without test strips,” said lead researcher Dr. Werner Mäntele of the university’s Institute for Biophysics. “Our goal is to devise an easier, more reliable and, in the long run, cheaper way to monitor blood glucose.”

In their PAS approach, a painless mid-IR laser pulse applied externally to the skin was absorbed by glucose molecules and created a measurable sound signature that the investigators call “the sweet melody of glucose.” This signal enabled them to detect glucose in skin fluids in seconds.

The data showed that the skin cell glucose levels at one-hundredth of a millimeter beneath the skin were related to blood glucose levels, Mäntele said.

Previous attempts to use PAS in this manner were hampered by distortion related to changes of air pressure, temperature and humidity caused by contact with living skin. To overcome these constraints, the team devised a design innovation of an open, windowless cell architecture. Although it is still experimental and would have to be tested and approved by regulatory agencies before becoming commercially available, the team is working to refine it.

In collaboration with Elté Sensoric of Gelnhausen, the researchers expect to have a small shoebox-sized device ready in three years, followed by a portable glucometer some years later.

The research was published in Review of Scientific Instruments (doi: 10.1063/1.4816723).