People have different views on tattoos: for some, this is the format of the latest art, for others it’s an unacceptable way of expressing oneself. Researchers in recent years have experienced temporary tattoos, detecting blood sugar or alcohol levels, as well as controlling a smartphone. Swiss doctors recently demonstrated a new development – a tattoo that can diagnose cancer. The technology is based on the determination of calcium in the blood. Elevated volumes of this element, or hypercalcemia, are often caused by cancer. That is why the tattoo darkens when the amount of calcium in the blood increases. This is a layer of specific cells that change their color and structure under the influence of calcium. The development has already been tested on mice. In 9 cases out of 10, the correct result was obtained. During laboratory tests, researchers measured the dynamics of melanin production at different concentrations of calcium ions. As it turned out, for a noticeable manifestation of a tattoo, it was necessary that the excess of the concentration of calcium ions was maintained for several weeks. Naturally, this result is far from ideal. Moreover, in the early stages of cancer, the level of calcium is not always stably high for a long time. However, researchers say they are still dealing with a prototype technology. In the future, the tattoo will become an assistant to a person in self-monitoring of their own health. Although, of course, the diagnostic tattoo has its drawbacks. She serves about a year, after which she will have to be replaced with a new one.