Scientists have figured out how to make human skin transparent

This unexpected method involves the use of a safe food colouring and could find a wide range of applications in medical diagnostics, from injury detection to disease monitoring and cancer diagnosis.

Astudy published in the journal Science has shown that it is possible to temporarily make tissues transparent using the FD&C Yellow 5 dye. The technique was tested on animals and the results were reversible - tissues quickly returned to normal after the dye was removed.

This technology could make veins visible for blood draws, simplify laser tattoo removal or help in early cancer diagnosis," said Stanford University professor Guosong Hong, one of the lead researchers.

The technique is based on using the gravitational lensing effect, which allows light to pass through tissue. This was made possible by careful calculations of how light interacts with different body tissues. The problem was that body tissues have different refractive indices, which scatters light and makes them opaque. The researchers found that if you use a dye to equalise these coefficients, light can pass through the tissues, making them transparent.

The main component of this technique was the food colouring tartarazine, better known as FD&C Yellow 5. It proved ideal for bringing the refractive indices of the tissues to a uniform level, which is what allowed light to pass through them without scattering.

The tests started with simple samples, such as chicken meat, and then the scientists moved on to live mice. In one experiment, the scientists applied a solution to the skin of a mouse's scalp, making it transparent and allowing them to observe blood vessels in the brain. In another test, making the abdomen transparent allowed them to see bowel movements and heartbeats.

The technique also proved useful for microscopic studies, with the effects of the dye disappearing minutes after it was washed off. The scientists suggest that further research, including dye injections, could lead to even deeper penetration of light into tissues, opening up new possibilities for biology and medicine.

The research was conducted as part of the Canadian CANUCS study.