If you are a primate or a koala, you’ve got something different compared to other animals: fingerprints. A new study explains how our fingerprints help us to keep a grip on the surfaces that we come in contact with and it’s all to try to do with regulating moisture.
Until now, it isn’t been fully clear how fingerprint ridges & the higher density of sweat glands underneath them, actually help us. Researchers decided to research on this using advanced laser imaging technology & discovered a finely tuned system controlling how wet or dry our fingertips are.
That means our fingers can react to the varied sorts of surfaces, they’re pushed up against making grip as strong as possible with everything from a phone to an umbrella and preventing ‘catastrophic slip‘ where we lose hold of objects.
“Primates evolve epidermal ridges on their hands & feet,” says chemical engineer Mike Adams from the University of Birmingham in the UK. “During contact with solid objects, fingerprint ridges are important for grip & precision manipulation.”
“They regulate moisture levels from external sources or the sweat pores, in order that friction is maximized & we avoid catastrophic slip & keep hold of that smartphone.”
Close-up laser imaging of 6 male volunteers touching glass showed that when fingertips make contact with hard, impermeable surfaces, extra moisture is released to extend friction & grip. However, the sweat pores are eventually blocked-off to avoid contacts that are too slippery.
This sweat pore blocking technique is combined with an accelerated evaporation process controlled by the ridges of the fingerprint that comes into play when excessive moisture must be removed again with the final aim of keeping a strong contact between finger & object.
Working together, the 2 biological mechanisms are able to adapt to surfaces whether our fingers are originally wet or dry: they provide the keratin skin layer with just the proper amount of hydration. That provides us skills that smooth-handed & smooth-footed animals do not have.
“This dual mechanism for managing moisture has provided primates with an evolutionary advantage in dry & wet conditions giving them manipulative & locomotive abilities not available to other animals like bears & large cats,” says Adams.
Fingerprint ridges have long been linked to better grip and former studies have checked-out variations in moisture, but now we know far more about the system that’s regulating how our fingers control that flow of moisture, particularly when it involves touching hard, smooth surfaces.
Besides telling us more about the human body, the research is probably going to help product designers who need to design a gadget that humans got to interact with like smartphone, for instance.
Further down the line, the findings might even benefit the development of grip on prosthetic limbs & robotic equipment, also as devices that are used to explore virtual reality game environments (where the feeling of touch might got to be simulated).
“Understanding the influence of finger pad friction will help-us to develop more realistic tactile sensors,” says Adams. “For example, applications in robotics & prosthetics & haptic feedback systems for touchscreens & virtual reality game environments.”
The research has been published in PNAS.