Water-immersion finger-wrinkling improves grip efficiency in handling wet objects

Abstract

For most people, immersing their hands in water leads to wrinkling of the skin of the fingertips. This phenomenon is very striking, yet we know little about why it occurs. It has been proposed that the wrinkles act to distribute water away from the contact surfaces of the fingertip, meaning that wet objects can be grasped more readily. This study examined the coordination between the grip force used to hold an object and the load force exerted on it, when participants used dry or wrinkly fingers, or fingers that were wet but not wrinkly. The results showed that wrinkly fingers reduce the grip force needed to grip a wet object, bringing that force in line with what is needed for handling a dry object. The results suggest that enhancing grip force efficiency in watery environments is a possible adaptive reason for the development of wrinkly fingers.

Mechanical Sensing in Embodied Agents

“…Therefore, objects are grasped more readily. Indeed, the force required to grip wet objects decreases by 20%, with a value in line with that needed for dry objects [23]. In general, the morphological changes due to wrinkling induce a variation in the mechanical interaction at the fingertip/object interface, and thus in the sensitivity of the inner receptors [24].…”