We’ve all done it.
We’re hustling home after a grocery store run and while juggling a bag of produce and snacks, we manage to drop our phones. But just before it gets too far away from us, we manage to catch it on the way down.
A recent study from the University of Birmingham reveals why.
Researchers at the Birmingham, England institution teamed with research institutions in South Korea, including Seoul National University and Yonsei University, according to a press release. They discovered when we touch impermeable surfaces, sweat from pores in the ridges of our finger pads makes the skin softer leading to significantly increased friction.
Yet eventually, that causes the sweat pores to become blocked so that prevents excess moisture that would diminish our capacity to grip objects.
“Primates have evolved epidermal ridges on their hands and feet. During contact with solid objects, fingerprint ridges are important for grip and precision manipulation. They regulate moisture levels from external sources or the sweat pores so that friction is maximized and we avoid ‘catastrophic’ slip and keep hold of that smartphone,” said co-author Mike Adams, a professor in product engineering and manufacturing, at the University of Birmingham.
“Understanding the influence of finger pad friction will help us to develop more realistic tactile sensors — for example, applications in robotics and prosthetics and haptic feedback systems for touch screens and virtual reality environments,” he added.
Scientists observed that moisture regulation could be explained by the combination of pore-blocking sweat and the quickened evaporation of excess moisture from surface wetting. This corresponds with the specific cross-sectional shape of fingerprints when touching an object, such as a smartphone in the case of human primates or monkeys and apes holding food or other items.
Both of those actions lead to maintaining the best amount of moisture in the fingerprint ridges that maximizes friction when the pads of fingers are initially wet or dry.
“This dual-mechanism for managing moisture has provided primates with an evolutionary advantage in dry and wet conditions — giving them manipulative and locomotive abilities not available to other animals, such as bears and big cats,” Adams added.
