Fingerprints may also wrinkle uniquely Premium

Discover how the unique wrinkling patterns on our fingertips could potentially be used for identification purposes in the future.

We use many features of our bodies to identify ourselves in government records. Fingerprints in particular are widely used, from unlocking phones with sensors to validating Aadhaar cards. But fingerprints can also be fickle. For example, if you spend an hour in the pool, a fingerprint sensor may no longer be able to read yours. This is because wrinkles will have formed on your fingertips.

Unlike raisins, which swell in water, the skin on our fingers contracts, creating a wrinkling pattern on the tips of our fingers. The discovery of this mechanism over two decades ago challenged the idea that wrinkles form when the skin on the finger swells. Upon further probing, scientists found that the shrinking may have evolved to help humans grip objects better underwater.

The wrinkling happens because when you are in water, the nerves in your fingertips send signals to the brain, which asks the blood vessels in the fingertips to contract.

When Binghamton University associate professor of biomedical engineering Guy German wrote about this for a children’s science magazine, a curious student asked: “Do the wrinkles always form the same way?” This led him to investigating whether the wrinkled pattern is as unique as the fingerprint. In a study published in May in the Journal of the Mechanical Behavior of Biomedical Materials, German and graduate student (recently graduated) Rachel Laytin reported just that.

The team found that the pattern is the same for an individual regardless of how many times it is forced to wrinkle. In their test, team members immersed hands in 40º C water for 30 minutes. Then they mapped the wrinkles and compared them to patterns formed 24 hours later, when the test was performed again. There were only a few small differences.

While fingerprints are two-dimensional motifs, wrinkling patterns are three-dimensional because they have trough-like low points and groove-like high points.

Fingerprints are personal and unique. Even identical twins do not have the same fingerprint.