Reversible Perspiring Artificial "Fingertips".

Fingertip perspiration is a vital process within human predation, to which our species owes its survival and its biological success. In this paper, we recreate the unique human ability of extensive perspiration and controlled friction in self-assembled cholesteric liquid crystals, mimicking the natural processes that occur in the dermis and epidermis of human skin. This is achieved by inducing porosity in our responsive, liquid-bearing material through the controlled-polymerization phase-separation process. The unique topography of human fingerprints is further emulated in our materials by balancing the parallel chirality-induced force and the perpendicular substrate-anchoring force during synthesis. As a result, our artificial fingertips are capable of secreting and re-absorbing liquid upon light illumination. By demonstrating the function of our soft material in a tribological aspect, it exhibits a controllable anti-sliding comparable to human fingertips and subsequently attains a higher degree of biomimicry. We envision this biomimetic fingertip being applied in a multitude of fields, ranging from biomedical instruments to interactive, human-like soft robotic devices. This article is protected by copyright. All rights reserved.