Rapid, Self-driven Liquid Mixing on Open-Surface Microfluidic Platforms

Area of Science:

• Microfluidics
• Surface Science
• Biomedical Engineering

Background:

• Surface micromixers offer potential for low-cost lab-on-a-chip (LOC) and point-of-care (POC) devices.
• Patterned wettability is a key technology for fabricating self-driven surface micromixers (SDSM).

Purpose of the Study:

• To present and analyze a novel SDSM design based on patterned wettability.
• To investigate the mixing mechanisms of micro-liter droplets on open substrates using SDSM.
• To provide design insights for optimizing surface microfluidic mixing devices.

Main Methods:

• Fabrication of SDSM by patterning wettable wedge-shaped tracks on a non-wettable surface.
• Utilizing wettability contrast and pattern geometry to drive droplet coalescence and flow.
• Incorporating non-wettable islands to augment mixing during capillary-driven transport.
• Testing various SDSM designs with different island configurations.

Main Results:

• Demonstrated mixing of micro-liter liquid volumes through coalescence and Laplace pressure-driven flow.
• Identified different mixing regimes based on SDSM design variations.
• Showcased the role of non-wettable islands in enhancing mixing efficiency.

Conclusions:

• SDSMs are effective for mixing small liquid volumes on open surfaces.
• The study provides valuable design principles for developing low-cost microfluidic mixing devices.
• This technology has significant implications for POC diagnostics and LOC applications.