How your skin reflects light sets you apart from everyone else

They look like pretty colour swatches, but those squares are made of human skin, and are being developed into a new diagnostic tool for doctors.

Researchers from the National Institute of Standards and Technology in the US have been investigating how the subtle differences in a person’s skin can be used for medical diagnoses and identification. 

The images above are a series of photos of skin samples taken from the insides of a number of volunteers’ forearms. Below these same images have been enhanced using a technique called ‘reflectance processing,’ which reveals how each skin sample reflects electromagnetic waves, or different frequencies of light. Our naked eyes can only see a small percentage of electromagnetic waves, but this technique shows up everything, from infrared to ultraviolet light.

According to Francie Diep at Popular Science, because the enhanced images are so distinct from one another, the research team is hoping to develop them into an identification method, for criminals and 'John Does', for example. "In addition,” says Diep, "some research groups are hoping to develop skin-imaging techniques that will tell doctors more about a person's health. Certain wavelengths of light could show how well skin is healing around a wound, for example.”

The researchers have published their findings in the journal Active and Passive Signatures V. The next step will be to expand and diversify the sample size to perfect the method. "With this preliminary data,” says Diep at Popular Science, "they determined the differences between individuals really are greater than instrument error, and the results suggest that visible and near-infrared wavelengths may be best for identification purposes.