Researchers at MIT and Harvard have created colour-changing tattoos that could, in the future, track your pH, glucose, and sodium levels.
The project, called DermalAbyss replaces traditional tattoo ink with biosensors, which respond to changes in the skin.
So far, the team, which consists of researchers from MIT and Harvard Medical School has developed three different inks that shift colour in response to changes in the interstitial fluid. Interstitial fluid is a thin layer of fluid which surrounds the body's cells and consists of 16% of body weight.
Of the three sensor inks, the most interesting is the one that can measure glucose levels. It changes its colour from blue to brown as blood sugar rises.
Having a glucose-sensing tattoo could make life easier for people with diabetes, who have to rely on pinprick blood tests throughout the day to monitor their glucose.
They have also created an ink that shifts from pink to purple if pH levels rise, and a third sensor that can detect sodium, shining a vibrant green hue under UV light in the presence of high salt levels.
So far this is only a research project and there are currently no plans to develop it into a product.
The researchers have tested the inks on patches of pig skin but before it can be approved in humans it will need to go through several stages of rigorous tests.