Bioinspired multi-structured hybrid surfaces for directional droplet transport and ultra-efficient atmospheric water collection

Abstract

In the context of global water scarcity, the development of efficient atmospheric water harvesting materials holds significant practical importance. Drawing inspiration from the natural water-collecting strategies of desert beetles, cacti, and plant leaf veins, this work presents the design and fabrication of a multi-structured bioinspired hybrid surface. The surface integrates a superhydrophobic coating, laser-engineered hydrophilic pores, Laplace-inspired superhydrophilic sharp-corner structures and a biomimetic guide channel. By precisely controlling the wettability gradient and geometric morphology, the hybrid interface enables highly efficient capture, coalescence, transport and detachment of fog droplets. Experimental results show that reducing the contact angle of hydrophilic pores to 6° boosts the baseline water collection efficiency to 3337 mg cm⁻² h⁻¹. Introducing sharp-corner structures further creates Laplace pressure gradients that promote directional coalescence and migration of droplets, increasing the efficiency to 5003 mg cm⁻² h⁻¹. The incorporation of guide channels effectively suppresses droplet pinning and accelerates transport, elevating the collection efficiency up to 7850 mg cm⁻² h⁻¹. High-speed imaging and simulation analyses reveal that wettability gradients enhance droplet capture and nucleation and corner structures strengthen the driving force for coalescence and migration, while guide channels establish continuous pathways for rapid droplet removal. The synergistic effect of these multiple structural elements enables a high-frequency “capture-coalescence-detachment” cycle. This study provides novel design strategies and theoretical insights for the development of high-performance and sustainable atmospheric water harvesting interface materials.