Sensors injected into the skin can detect glucose levels, UV light exposure, and body temperature, offering hope of simple and trendy health monitoring.

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Researchers have developed a new form of tattoo ink that can respond to changes in your body’s chemistry. Getty Images

Long known as a permanent form of body art, tattoos may soon serve a medical function.

Several groups of scientists are developing sensors that can be injected into the skin to monitor levels of blood glucose and other health biomarkers.

A team at the Technical University of Munich in Germany identified three chemical sensors that change color in response to biomarkers — glucose, albumin, or pH — in the fluids between the body’s cells.

One chemical sensor turns green in the presence of albumin. Decreasing levels of this protein may indicate kidney or liver failure.

Another sensor changes from yellow to dark green as the glucose level increases. High glucose level is a sign of poorly managed diabetes.

The third sensor turned from yellow to blue as the pH level increased from slightly acidic to alkaline.

So far, the researchers have only tested these chemical sensors on a piece of pig skin. Additional testing would be needed before they could be used in people.

The results were recently published in the journal Angewandte Chemie International Edition.

Tattoos may also one day help people monitor the environment’s effect on their body.

A team of researchers at the University of Colorado Boulder has developed a tattoo sensor that only shows up on the skin when exposed to UV light. This could alert people that their sunscreen has worn off.

Another skin sensor becomes visible at different temperatures, which would provide people with a built-in thermometer.

These sensors are in the testing phase and aren’t yet ready for use in people.

This group has also been working on another tattoo prototype that could conduct electricity. This type of tattoo might be used to recharge the battery on a biomedical implant, such as a pacemaker, simply by sending electricity along the tattoo to the device.

Although the tattoo doesn’t yet carry as much electricity as a copper wire, the team’s leader, Carson Bruns, PhD, is optimistic about the technology.

“We’re making progress, and I’m really excited about this because I think that it could open up a whole new world of possibility for tattoos,” said Bruns, an assistant professor in nanotechnology at the University of Colorado Boulder, in a TEDxMileHigh talk.

“I envision a future where tattoos enable us — tattoo-able wires and tattoo-able electronics enable us — to merge our technologies with our bodies so that they feel more like extensions of ourselves rather than external devices,” he said.

The big question, though, is how willing people will be to get a tattoo, even if it’s more medical than aesthetic (although there’s no reason they can’t be both).

In a study published earlier this year in the Canadian Journal of Diabetes, researchers asked 195 people with diabetes about their comfort level with different types of advanced glucose monitoring technology.

People with type 1 diabetes were more likely to prefer tattoo glucose sensors than people with type 2 diabetes. Also, women and people under 30 years of age were more likely to be comfortable having a tattoo sensor.

This study asked people about permanent tattoo sensors, but there are other options being developed.

A group of researchers from UC San Diego are working on temporary tattoo sensors that can monitor glucose levels in sweat on the skin.

Like the temporary tattoos you may have used as a child, you apply this device to the skin by dabbing it with water and removing the paper on the back.

The tattoo contains two electrodes that apply a small amount of electrical current, which forces glucose molecules in the skin to come to the surface, where they can be measured.

The device is currently being tested on people in a phase I clinical trial. The researchers will compare the results of the tattoo sensor to finger-stick glucose readings. More testing will be needed before this could be available to the public.

Dr. Edward Chao, one of the researchers on this project and a Clinical Professor of Medicine at UC San Diego, said “the advantage of this kind of technology is that it’s completely noninvasive” — aka painless.

It’s also less cumbersome, he says, which is ideal for people with an active lifestyle.

And since you wear the device for long periods, you wouldn’t have to worry about remembering to bring your glucose monitoring equipment when you leave the house.

Chao says although technology like this can help people regularly monitor their glucose, it doesn’t necessarily replace motivation.

Barriers other than pain can also keep people from tracking their glucose — including being uncomfortable with new technology.

“Technology can help,” Chao said, “but by itself, it doesn’t necessarily get people to check their glucose more often. I think we have to be mindful of that.”