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Programmable Milli-Microfluidics via Oxide-Mediated Continuous Electrowetting of Liquid Metal Droplets
Xu Gao1, Shitao Shen1, Peiyue Li1
1School of Integrated Circuits, Peking University, Beijing, China.
Advanced Materials (Deerfield Beach, Fla.)
|April 9, 2026
Summary
Interfacial oxide layers on liquid metals (LM) enable programmable flow control, reversing jet direction without altering electrical signals. This breakthrough allows for advanced milli-microfluidic systems.
Area of Science:
- Materials Science
- Fluid Dynamics
- Electrochemistry
Background:
- Interfacial oxide layers on gallium-based liquid metals (LM) typically hinder electrohydrodynamic actuation.
- Previous models failed to reconcile theoretical predictions with experimental observations in continuous electrowetting (CEW).
Purpose of the Study:
- To demonstrate that interfacial oxides can be utilized for programmable flow field control in LM systems.
- To develop a model explaining the role of interfacial redox reactions in CEW.
- To enable novel milli-microfluidic applications through oxide-mediated flow manipulation.
Main Methods:
- Development of a Faradaic depolarization model incorporating interfacial redox reactions.
- Experimental investigation of liquid metal flow regimes under varying electrical excitations.
- Characterization of oxide coverage effects on flow direction and pattern.
Main Results:
- Oxide coverage was found to dictate flow direction and pattern, allowing for flow reversal without changing electrical inputs.
- Four distinct flow regimes were experimentally identified, matching model predictions.
- Demonstrated bubble-free pumping, reconfigurable fluidic logic, and sustained operation over 19 hours.
Conclusions:
- Interfacial oxides are key to programmable flow control in LM systems, not just obstacles.
- The developed model resolves discrepancies in CEW theory and practice.
- This work enables multi-mode, long-term operation for intelligent milli-microfluidic devices.
