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Updated: Apr 26, 2026
07:18
Measuring the Interaction Force Between a Droplet and a Super-hydrophobic Substrate by the Optical Lever Method
Published on: June 14, 2019
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Scale effect on dropwise condensation on superhydrophobic surfaces
Ching-Wen Lo1, Chi-Chuan Wang, Ming-Chang Lu
1Department of Mechanical Engineering, National Chiao Tung University , Hsinchu, Taiwan.
ACS Applied Materials & Interfaces
|July 29, 2014
Summary
Superhydrophobic surfaces with micro/nano structures may hinder condensation droplet shedding. Nanostructures promote efficient droplet removal, while microstructures can cause pinning. Optimize surface design for better performance.
Area of Science:
- Surface science
- Materials science
- Thermodynamics
Background:
- Micro/nano (two-tier) structures are commonly used to create superhydrophobic surfaces.
- Superhydrophobicity does not always guarantee efficient droplet shedding during condensation.
- Macroscopic Cassie droplets on these surfaces often exhibit partial Wenzel wetting at the microscale.
Purpose of the Study:
- To investigate the effectiveness of micro/nano structures in condensation droplet shedding.
- To understand the wetting behavior (Cassie vs. Wenzel) of droplets on two-tier superhydrophobic surfaces.
- To identify design parameters for achieving efficient liquid droplet shedding during condensation.
Main Methods:
- Analysis of droplet behavior on micro/nano structured surfaces during condensation.
- Evaluation of the influence of surface topography on droplet departure diameter and wetting states.
- Theoretical assessment using dimensionless numbers like the Bond number.
Main Results:
- Two-tier surfaces may not be advantageous for condensation; microstructures can lead to pinned Wenzel droplets.
- Nanostructure-roughened surfaces show potential for efficient liquid droplet shedding.
- Increased contact angle from microstructures can increase droplet departure diameter, reducing performance.
Conclusions:
- Efficient droplet shedding requires careful surface design, favoring nanostructures over microstructures.
- For efficient shedding, a Bond number < 0.1 and a solid-liquid fraction < 0.3 are suggested for superhydrophobic surfaces.
- Understanding the interplay between surface structure and wetting is crucial for optimizing condensation performance.
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