Smart tattoos could monitor vital signs

Tattoos have come a long way from their initial association with bearded and beefy macho males driving around in Harley Davidsons. Tattoos have grown from being a symbol of dissent to becoming a form of body art used for decorative or pictorial purposes, or to make a fashion statement. Now tattoos have gained an added respectability quotient by entering the field of science and medicine.

Researchers at the Technical University in Munich, Germany have developed chemical sensors that can be injected into the skin to monitor blood glucose and other health markers. The research team identified three chemical sensors, often used in tattoos, which 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. And, the third sensor turns from yellow to blue as the pH level increases from slightly acidic to alkaline.

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

Tattoos may also one day help people monitor the environment’s effect on their body. A team of researchers at the University of Colorado in the US 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 are not yet ready for use in people.

The researchers in the US have 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 does not as yet carry much electricity as a copper wire, the team’s leader, is optimistic about the technology. “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 is for medical rather than aesthetic reasons.The permanency of tattoos is a big drawback for many people. But there are other options being developed. A group of researchers in the US are working on temporary tattoo sensors that can monitor glucose levels in sweat on the skin.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. The advantage of this kind of technology is that it is completely noninvasive and also less cumbersome, which is ideal for people with an active lifestyle.