Next-gen blood glucose monitor: High-tech tattoos

Chemical engineers at MIT are designing carbon nanotubes that can be injected beneath the skin to reveal continuous blood glucose levels in real time. If it works, people with Type I diabetes may not have to prick their fingers multiple times a day to monitor their glucose levels.

Dubbed a "tattoo" that's designed to detect glucose, the nanotubes are wrapped in a polymer that is sensitive to glucose concentrations. A wearable device roughly the size of a wristwatch shines infrared light through the skin and onto the nanotubes, which fluoresce when in contact with glucose.

So it's really a tattoo in hiding. And at this point the sensor is estimated to have a shelf (or is it skin?) life of roughly six months.

But the team, which plans to start testing on animals soon, says that if the readings are accurate enough to pass the Clarke Error Grid analysis for glucose sensor accuracy, the system could revolutionize continuous glucose monitoring.

"The most problematic consequences of diabetes result from relatively short excursions of a person's blood sugar outside of the normal physiological range, following meals, for example," said Michael Strano, a professor at MIT's Department of Chemical Engineering. "If we can detect and prevent these excursions, we can go a long way toward reducing the devastating impact of this disease."

While the MIT sensor appears to be the first of its kind, it is by no means the only continuous glucose sensor. Strano says that most work by injecting the enzyme glucose oxidase, which breaks down glucose and indirectly measures glucose levels based on interactions with a byproduct of the breakdown, hydrogen peroxide. Because of the risk of easy infection, this method is only approved to last for up to a week at a time.

The MIT sensor, on the other hand, takes more direct measurements with a passive device that simply absorbs and re-emits light--a process Strano tells me should be quite safe.

"The device really only has to absorb and emit. It doesn't have to be self-powered, and doesn't have to contain anything else except fluorophore," he said. "We're very excited about this; we have a series of patents on it, and we're very committed to getting this to work."

The engineers first described their sensor in the journal ACS Nano in November 2009, and are now working on the "ink" the nanotubes would be suspended in when injected beneath the skin.