Fingerprint Humidity Control Mechanism Is Conducive to the Development of Better Robots and Other Eq

Primates, including humans, monkeys and apes, have evolved epidermal ridges on their hands and feet, and the density of sweat glands here is higher than elsewhere in the body. This allows them to accurately adjust skin moisture and provide greater grip when manipulating objects. A new study conducted by the University of Birmingham in the UK in cooperation with researchers from research institutions such as Seoul National University and Yonsei University in South Korea shows that the water regulation mechanism of fingerprint can not only help people better grasp objects, but also help scientists develop better prosthetics, robot human equipment and virtual reality environment. Relevant research results were published in the Journal of the National Academy of Sciences.

Fingerprints help to increase the friction when contacting with smooth surfaces and enhance the grip and tactile sensitivity to rough surfaces. The moisture regulation mechanism of fingerprint ensures the optimal hydration state of skin cuticle, so as to maximize friction.

"Primates have evolved epidermal ridges on their hands and feet. Fingerprint ridges are very important for grasping and accurately manipulating solid objects. They can adjust the water released from external sources or sweat glands, so as to maximize friction, avoid 'catastrophic' sliding, and enable us to hold smartphones." the co-author of the research paper Mike Adams, a professor of product engineering and manufacturing at the University of Birmingham, said that understanding the impact of finger fingerprint ridge friction will help researchers develop more realistic tactile sensors. For example, sensors applied to robots and prosthetics, and tactile feedback systems in touch screens and virtual reality environments.

Ultrasonic lubrication is usually used for touch screen displays that provide sensory "tactile" feedback, but compared with wet fingerprint ridges, the effect of ultrasonic lubrication will be reduced when the user is in a dry environment. In addition, the identification of fine structured surfaces such as fabrics by touch depends on the induction of lateral vibration, so the lack of sliding friction will hinder the identification of what is actually in contact.

Fingerprint is unique to primates and koalas. It seems to have a dual role. It not only promotes the evaporation of excess water, but also provides a water reservoir at the bottom to maximize grip strength.

The researchers found that when the finger contacts the impermeable surface, the sweat in the pores of the fingerprint ridge will make the skin softer, which significantly increases the friction. The increased compliance of ridge sweat will eventually lead to pore blockage, prevent the release of too much water, and reduce the ability to grasp objects.

Using high-tech laser imaging technology, scientists found that water regulation consists of two parts, namely, the above sweat hole blocking process and the accelerated evaporation of external excess water caused by the change of specific cross-sectional shape of epidermal ridge when contacting objects.

Whether the finger belly is wet or dry at first, the above two processes keep the fingerprint ridge at the best humidity, so as to maximize the friction.

"This dual mechanism of water regulation provides primates with evolutionary advantages in dry and wet environments, giving them the ability to manipulate and move objects, which other animals, such as bears and large cats, do not have," Adams added.