A tattoo which changes colour to reflect movements in blood glucose levels has been created by German scientists.
So far, the team from Technical University of Munich have successfully tested out the concept on the skin of pigs.
Led by Dr Ali Yetise, a chemical engineer, the team used a colour-changing dye to pick up changes in blood glucose levels, with a view to helping people manage diabetes. They also experimented on picking up albumi, a marker of kidney disease, and used another dye to measure the pH level in blood.
The dyes react to changes in the three biomarkers in the interstitial fluid. This fluid acts as a reservoir of nutrients including glucose. The level of glucose in interstitial fluid rises and falls in response to increases and decreases in blood glucose levels.
The researchers explained that the glucose sensor picked up on chemical changes in blood glucose levels, leading to the changing in the dye from yellow to dark green.
The albumin sensor reacts to the presence of albumin by turning green and the pH sensor uses red and blue dye, with the sensor turning yellow to blue when the pH level is normal for human blood.
The dyes, apart from the Ph level, are not yet reversable but the scientists say the study represents a first step in developing tattoos which help people with diabetes and kidney disease manage their conditions in real-time.
In the research paper, the scientists said: “Body modification by injecting pigments into the dermis layer is a custom more than 4,000 years old. Here, a functional cosmetic technology was developed by combining tattoo artistry and colorimetric biosensors… Dermal tattoo sensors functioned as diagnostic displays by exhibiting colour changes within the visible spectrum in response to variations in pH, glucose, and albumin concentrations.”