Advances in Directional Wetting Surfaces for Enhanced Fluid Control: A Comprehensive Review

Abstract

Controlling surface wettability and directing the flow of working fluids havecrucial implications in various natural and engineering contexts.Understanding the fundamental principles of wettability and directionalwetting is essential for effectively leveraging these phenomena to enhance theperformance of engineering systems, such as microfluidics or heatexchangers. This comprehensive review summarizes of previous research,emphasizing recent advances by categorizing the structures and workingprinciples associated with directional wetting surfaces. The efforts ofresearchers who have employed diverse strategies to manipulate the wettingbehavior of liquids through both passive and active control mechanisms arehighlighted. Passive directional transport surfaces require no additionalenergy while enabling large-scale and continuous fluid control. Conversely,active directional wetting surfaces offer enhanced flexibility and precisecontrol of liquid movement. Furthermore, insights into recent studies thatfocused on practical applications are provided and the current challenges thatneed to be addressed are discussed. This study serves as a guide for futureresearch directions on the development of directional wetting surfaces andoffers valuable recommendations for practical implementation.