Recent progress in beetle-inspired superhydrophilic-superhydrophobic micropatterned water-collection materials

Abstract

Biological creatures with unique surface wettability have long served as a source of inspiration for scientists and engineers. More specifically, certain beetle species in the Namib Desert have evolved to collect water from fog on their backs by way of wettability patterns, which attracted an ongoing interest in biomimetic studies. Bioinspired materials exhibiting extreme wetting properties, such as superhydrophilic and superhydrophobic surfaces, have attracted considerable attention because of their potential use in various applications. Combining these two extreme states of superhydrophilicity and superhydrophobicity on the same surface in precise two-dimensional micropatterns opens exciting new functionalities and possibilities for a wide variety of applications. In this review we briefly describe the water-harvesting mechanisms of a genus of Namib Desert beetle, Stenocarpa, consisting of the theory of wetting and transporting. Then we describe the methods for fabricating superhydrophilic-superhydrophobic patterns and highlight some of the newer and emerging applications of these patterned substrates that are currently being explored. Finally, we provide conclusions and outlook concerning the future development of bioinspired surfaces of patterned wettability.

Patterned Hybrid Wettability Surfaces for Fog Harvesting

“…Inspired by the unique water-harvesting ability of insects and plants, the driving force produced by surface energy gradients exhibits great water-harvesting abilities. Based on the wettability principle, water harvesting on a solid surface can be divided into three steps: condensation, coalescence, and rapid transportation of water droplets. − As shown in Figure , there is a wettability gradient on the surface of the composite membrane. Small water droplets aggregate and condense in the superhydrophobic region of the membrane surface once they come into contact with it, forming microscopic droplets.…”

Recent Development of Atmospheric Water Harvesting Materials: A Review

“…A variety of functional materials, such as amphiphilic surfaces and artificial cactus spines, have been developed for saturated (fog) water harvesting, − and some novel aerodynamic designs have been inspired by other surface morphologies. For example, Harris et al reported a biomimetic structured surface for atmospheric saturated water harvesting inspired by the Stenocara beetle, which has an irregular textured shell with hydrophilic sites on its hydrophobic shell background. − To mimic this unique structure, hydrophobic polystyrene (PS) and hydrophilic poly­(4-vinylpyridine) (P4VP) were subsequently coated on a substrate to afford a dual-layered coating (Figure ). Due to poor compatibility, the P4VP segments tend to minimize its contact areas with PS under high-temperature annealing, resulting in the connection among isolated P4VP spheres on top of the PS layer.…”

Biomimetics provides lessons from nature for contemporary ways to improve human health

“…Ingenious solutions that evolved to withstand extreme temperatures in the animal kingdom may provide hints for the treatment of human diseases in an era of global warming. One of the best examples of an ingenuous solution comes from a certain beetle species in the Namib Desert that have evolved a system to collect water from the fog on their backs by way of wettability patterns [49]. The Arabian camel has developed an amazing capacity to cope with extreme heat stress and drought without any physiological impairment.…”