Surface-Tension-Confined Channel with Biomimetic Microstructures for Unidirectional Liquid Spreading

Area of Science:

• Biomimetics and Materials Science
• Fluid Dynamics
• Microfluidics

Background:

• Unidirectional liquid spreading without external energy is crucial for applications like water harvesting and oil-water separation.
• Controlling liquid motion and simplifying manufacturing for such systems remain significant challenges.

Purpose of the Study:

• To design and fabricate a novel surface-tension-confined (STC) channel inspired by *Nepenthes alata*.
• To achieve controllable, energy-free unidirectional liquid spreading using biomimetic microcavities.
• To explore the potential for complex liquid manipulation in microfluidic applications.

Main Methods:

• Fabrication of STC channels using UV exposure photolithography and partial plasma treatment.
• Integration of biomimetic microcavities and hydrophobic boundaries to control liquid spreading.
• Investigation of microcavity structural features and their impact on liquid spreading and pinning.

Main Results:

• Achieved perfect asymmetric liquid spreading with stable pinning effects.
• Demonstrated spontaneous unidirectional liquid transport in 3D space and on inclined surfaces.
• Successfully realized complex liquid motion paths and microreactors by altering pit arrangement and wettability.

Conclusions:

• The biomimetic STC channel provides an effective platform for energy-free unidirectional liquid manipulation.
• This technology offers a new paradigm for advanced microfluidic devices and lab-on-chip systems.
• The facile fabrication process and versatile liquid control pave the way for diverse applications.