Bioinspired Cilia Array Surfaces for Programmable Unidirectional Liquid Transport across Surface Tension Regimes

Area of Science:

• Surface science and microfluidics
• Bioinspired engineering and materials science

Background:

• Unidirectional liquid transport is crucial for applications like water harvesting and microfluidics.
• Current methods face limitations with narrow surface-tension ranges, hindering broader applicability.

Purpose of the Study:

• To design and investigate bioinspired asymmetric cilia arrays (BACAs) for robust unidirectional liquid transport.
• To explore the influence of surface tension, surface energy, and cilia spacing on transport dynamics.
• To develop a theoretical framework for predicting and controlling liquid transport modes.

Main Methods:

• Fabrication of bioinspired asymmetric cilia arrays mimicking *Alchemilla mollis* cilia.
• Systematic experimental studies on liquid transport across a wide surface-tension range (22.2-72.8 mN m⁻¹).
• Development of a theoretical model based on bidirectional transport contact angle for quantitative analysis.

Main Results:

• BACAs achieved unidirectional liquid transport over an ultrabroad surface-tension range.
• Transport modes (forward, reverse, bidirectional) were observed to be dependent on surface tension, surface energy, and cilia spacing.
• A predictive framework accurately quantified transport modes, enabling programmable liquid routing.

Conclusions:

• The developed BACAs offer a versatile platform for controlled liquid transport, overcoming limitations of existing technologies.
• The theoretical framework provides a valuable tool for designing advanced microfluidic devices and systems.
• This research opens new avenues for efficient atmospheric water harvesting, microfluidics, and heat transfer applications.