A multi-structural and multi-functional integrated fog collection system in cactus

TLDR

Biological structures such as beetle backs, spider silk, and cactus spines have evolved to collect fog, enabling species like Opuntia microdasys to survive in arid environments. The study aims to elucidate the structure–function relationship of the cactus’s fog‑collection system to inspire high‑efficiency fog‑harvesting materials. The cactus’s fog‑collection system consists of clusters of conical spines and trichomes whose integrated surface features create gradients in Laplace pressure and surface‑free energy, enabling efficient water capture. The study demonstrates that clusters of conical spines and trichomes on Opuntia microdasys efficiently collect fog, constituting a key survival mechanism.

Abstract

Multiple biological structures have demonstrated fog collection abilities, such as beetle backs with bumps and spider silks with periodic spindle-knots and joints. Many Cactaceae species live in arid environments and are extremely drought-tolerant. Here we report that one of the survival systems of the cactus Opuntia microdasys lies in its efficient fog collection system. This unique system is composed of well-distributed clusters of conical spines and trichomes on the cactus stem; each spine contains three integrated parts that have different roles in the fog collection process according to their surface structural features. The gradient of the Laplace pressure, the gradient of the surface-free energy and multi-function integration endow the cactus with an efficient fog collection system. Investigations of the structure–function relationship in this system may help us to design novel materials and devices to collect water from fog with high efficiencies. Biological structures such as the backs of beetles and spider silk have fog-collecting properties. Here, clusters of conical spines and trichomes on the stem of the cactus O. microdasysare found to be responsible for its fog-collecting abilities.