(ORDO NEWS) — If you are a primate or koala, you have something different from other animals: fingerprints. And new research is explaining how our fingerprints help us hold onto surfaces we come in contact with – all related to moisture regulation.
Until now, it was not clear how the fingerprint ridges and the higher density of sweat glands underneath actually help us. Researchers decided to investigate this with advanced laser imaging technology and discovered a finely tuned system that controls how wet or dry our fingertips are.
This means that our fingers are able to respond to the different types of surfaces they touch, making our grip as strong as possible with everything from the phone to the umbrella, and preventing “catastrophic sliding” when we lose objects.
“Primates have developed epidermal ridges on their arms and legs,” says chemical engineer Mike Adams of the University of Birmingham in the UK. “When in contact with hard objects, the fingerprint ridges are essential for grip and precise handling.
“They regulate moisture levels from external sources or sweat pores so that friction is maximized and we avoid slipping and hold this smartphone.”
Close-up laser scans of six male volunteers touching the glass showed that when their fingertips touch hard, impenetrable surfaces, additional moisture is released, increasing friction and grip. However, the pores for sweat will eventually close to avoid too slippery contacts.
This pore-blocking technique is combined with an accelerated evaporation process controlled by the fingerprint ridges that comes into play when excess moisture needs to be removed – again with the ultimate goal of maintaining strong contact between the finger and the object.
Working together, two biological mechanisms are able to adapt to surfaces, regardless of whether our fingers were initially wet or dry: they provide the keratin layer of the skin with the right amount of moisture. This gives us skills that animals with smooth arms and legs do not have.
“This dual mechanism of moisture management has given primates an evolutionary advantage in dry and wet conditions, giving them manipulation and locomotion abilities that other animals such as bears and big cats cannot,” says Adams.
In addition to learning more about the human body, this research is likely to help product designers who need to develop a gadget that people need to interact with, such as a smartphone.
“Understanding the impact of fingertip friction will help us design more realistic tactile sensors,” says Adams. “For example, applications in robotics and prosthetics, as well as haptic feedback systems for touch screens and virtual reality environments.”
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