Researchers at the University of Illinois have developed a continuous glucose-monitoring system that changes color when glucose levels vary.

Paul Braun and Chunjie Zhang developed the monitoring material, which has an accurate wavelength shift. The duo said it will be helpful for doctors and patients to use the device for automatic insulin dosing.

The sensor is made of hydrogel, a soft elastic jelly-like material, mixed with boronic acid compounds. Boronic acid binds with glucose, resulting in gel which expands as the glucose concentration increases. The hydrogel is lined with photonic crystals made of tiny arranged beads. A photonic crystal reflects just one wavelength of light, while the rest of the spectrum passes through. As the hydrogel expands, the reflected color shifts from blue to green to red.

Researchers say the hydrogel is akin to an advanced device that taps into the bloodstream like an insulin pump. But most importantly, the device will be beneficial for patients in intensive care who require continuous monitoring.

"There are significant limitations to current continuous glucose monitoring technologies," said lead study author Paul Braun, a professor of materials science and engineering at the University of Illinois. "The systems available today all have some combination of limited sensitivity, limited precision and frequent recalibration. Using today's systems, you can determine trends in glucose levels, but without frequent recalibration, you don't have the accuracy or reliability to use that to make insulin dosing decisions or to drive autonomous dosing."

Braun said the color-changing material was simple and cost-effective. Just a square inch of the hydrogel would be sufficient for 25 patients.