(Inside Science TV) -- Tattoos come in all shapes and sizes. A new kind of temporary tattoo could become a kind of health monitor.
"We think about it as a second skin layer," said John Rogers, a materials scientist and physical chemist at the University of Illinois at Urbana-Champaign.
"It's kind of the next-generation wearable technology -- technology that by virtue of its intimate contact with the skin could provide clinical-quality data," said Rogers. The stick-on tattoo could monitor heart health by measuring the body's blood flow through the skin.
"Blood flow rate by itself is a very important measurement," said Yonggang Huang, an engineer at Northwestern University in Evanston, Illinois. "Once your blood flow rate changes, it may be an indication of a heart condition."
The tattoo measures blood flow rates by responding to temperature changes in the body.
"This patch is composed of liquid crystals that change color with temperature," said Huang.
Temperature changes detected across the liquid crystals can signal increases and decreases in blood flow, skin hydration and heart rate.
You can place it on your neck or on your arm and leave it there for two weeks. If it changes color, you know you have a problem.
"That color difference will allow you to be able to map your blood flow, different veins, and tell you about your cardiac health and different physiological things in your body," said Anthony Banks, an engineer at the University of Illinois.
Using a special smartphone app, you can snap a photo of the patch and the temperature data is translated into a health report -- all within thirty seconds.
The versatile tattoo can do more than take temperature, though.
"We can determine skin hydration. We can measure lots of electrical signals associated with activity in the brain, the heart, the skeletal muscles," said Rogers.
The 3,600 liquid crystals sit on a flexible material that stretches, compresses and twists with the skin. The wearer may even forget they have it on.
"If one's health can be monitored 24/7 and it can tell you to see a doctor before something bad happens, that's a huge savings, not only in money, but saving one's life," Huang emphasized.