For patients with diabetes, measuring and monitoring blood sugar levels throughout the day is vital for keeping their condition in check. But the finger-prick method of testing blood sugar deters many patients who find the tests too difficult or unpleasant to perform. Now, diabetes patients may have a new noninvasive method for blood sugar monitoring that's as easy as applying a temporary tattoo.

Nanoengineers at the University of California, San Diego have designed a flexible sensor that can be printed on temporary tattoo paper and applied to the skin to test blood sugar levels. The sensor uses a mild electrical current to measure glucose levels in a person’s body. It's inexpensive, easy-to-use, and best of all, painless.

The tattoo is a series of carefully placed electrodes that measure glucose molecules in the fluid of the skin. It gives off a very mild electrical current that forces sodium ions in the fluid towards the tattoo's electrodes, carrying glucose molecules with them along the way. The sensor built into the tattoo uses this information to measure overall glucose levels. 

To test the new device, the research team evaluated seven healthy, non-diabetic patients between the ages of 20 and 40. According to a UC San Diego news release, none of the participants reported feeling any irritation or discomfort from the tattoo, while a few felt some mild tingling within the first 10 seconds of wearing it. To test how well the tattoo was able to pick up changes in glucose levels, researchers asked volunteers to eat a carb-rich meal and drink a soda in the lab. The device performed just as well as the traditional finger prick in detecting the glucose spike from the meal.

With the current prototype, the tattoo must be removed so that glucose levels can be analyzed, but researchers are hoping that this early design will lead to a model that can display numeric glucose levels right on the tattoo. Researchers are also working on embedding Bluetooth capabilities into the tattoo, meaning blood sugar data could be sent directly to a patient's doctor or smartphone. They also envision other uses for the design, such as monitoring prescription drug levels, proteins, metabolites, or even illegal drugs or alcohol levels — all without the dreaded poke from a needle.

This research was published in the journal Analytical Chemistry (pdf).

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