Desert beetle-inspired fog-harvesting surfaces integrating buckled microchannels and alternating wettability

Abstract

In this study, we present a novel fog-harvesting surface featuring buckled microstructures with alternating hydrophilic–hydrophobic regions, inspired by the elytra of desert beetles. The surface was fabricated by dispersing hydrophilic SiO₂ particles on hydrophobic polytetrafluoroethylene (PTFE) buckled patterns. The hydrophilic protrusions promote droplet condensation and capture, whereas the hydrophobic buckled surfaces, functioning similarly to microchannels, facilitate directional transport to enhance water collection. Compared to flat surfaces, buckled structures can improve water collection efficiency by approximately 30%. This design with alternating wettability was systematically compared with fully hydrophilic and fully hydrophobic surfaces. Various parameters, including the fog flow distance, hydrophilic particle composition, surface wettability distribution, and buckle alignment, were investigated. Furthermore, the geometric funnel-shaped growth pattern of bird's nest fern leaves was incorporated to guide condensed droplets toward the collection zone, forming a dual-biomimetic mechanism that integrates microscale desert beetle-inspired structures with macroscale fern-inspired geometry. Real-world field tests—specifically, overnight fog collection experiments conducted in a forest environment—further confirmed the excellent performance of our device. Notably, the entire fabrication process can be conducted under ambient conditions; high-vacuum techniques and costly equipment are not required. The developed high-efficiency fog-harvesting device offers a scalable, sustainable, and inexpensive solution to atmospheric water collection, contributing to improved water accessibility in water-scarce regions.