Chemical engineers are working on carbon nanotubes that could be injected under the skin to reveal blood glucose levels.

Paul Barone, a postdoctoral researcher in MIT’s Department of Chemical Engineering and professor Michael Strano are working on a new type of blood glucose monitor that could not only eliminate the need for finger pricks but also offer more accurate readings.

“Diabetes is an enormous problem, global in scope, and despite decades of engineering advances, our ability to accurately measure glucose in the human body still remains quite primitive,” says Strano.

Strano and Barone’s sensing system consists of a “tattoo” of nanoparticles designed to detect glucose, injected below the skin. A device similar to a wristwatch would be worn over the tattoo, displaying the patient’s glucose levels.

The technology behind the MIT sensor is based on carbon nanotubes wrapped in a polymer that is sensitive to glucose concentrations. When this sensor encounters glucose, the nanotubes fluoresce, which can be detected by shining near-infrared light on them. Measuring the amount of fluorescence reveals the concentration of glucose.

The researchers plan to create an “ink” of these nanoparticles suspended in a saline solution that could be injected under the skin like a tattoo. The “tattoo” would last for a specified length of time, probably six months, before needing to be refreshed.

To get glucose readings, the patient would wear a monitor that shines near-infrared light on the tattoo and detects the resulting fluorescence. One advantage of this type of sensor is that, unlike some fluorescent molecules, carbon nanotubes aren’t destroyed by light exposure. “You can shine the light as long as you want, and the intensity won’t change,” says Barone. Because of this, the sensor can give continuous readings.