Cactus-Inspired Janus Membrane with a Conical Array of Wettability Gradient for Efficient Fog Collection

Area of Science:

• Materials Science
• Surface Engineering
• Fluid Dynamics

Background:

• Global water scarcity necessitates advanced fog collection technologies.
• Existing bionic surfaces face challenges with droplet adhesion, hindering continuous fog collection.
• Lotus leaves and cactuses offer natural models for efficient water management.

Purpose of the Study:

• To design and develop a Janus membrane for simultaneous fog collection and directional transport.
• To overcome limitations of droplet adhesion and improve water transport efficiency in fog harvesting.
• To create a novel material for efficient water management and microfluidic applications.

Main Methods:

• Fabrication of a Janus membrane with conical microcolumns exhibiting a wettability gradient (superhydrophobic apexes, hydrophobic sides).
• Integration of a hydrophilic copper mesh base for water transport.
• Characterization of droplet behavior, including deposition, coalescence, and directional transport.
• Performance evaluation of the fog collection efficiency.

Main Results:

• The Janus membrane demonstrated efficient fog droplet deposition, coalescence, and directional transport.
• Droplets successfully passed through the membrane and formed a water film on the copper mesh.
• Achieved a high fog collection rate of approximately 7.05 g/cm²/h.
• The asymmetric structure and wettability gradient were key to enhanced performance.

Conclusions:

• The developed Janus membrane effectively collects fog and facilitates directional water transport.
• This biomimetic design significantly improves fog collection efficiency compared to conventional methods.
• The study provides valuable insights for designing advanced fluid control equipment in fog collection and microfluidics.