Electrokinetic Microfluidics at the Convergence Frontier: From Charge-Driven Transport to Intelligent Chemical...

Area of Science:

• Microfluidics
• Analytical Chemistry
• Physical Chemistry

Background:

• Electrokinetics is a foundational technique in microfluidics for non-mechanical fluid and analyte manipulation.
• Key electrokinetic mechanisms include electroosmotic flow (EOF), electrophoresis (EP), and dielectrophoresis (DEP).
• Complex systems involving heterogeneous interfaces, viscoelastic liquids, and anisotropic droplets present new challenges and opportunities.

Purpose of the Study:

• To review and highlight five prominent research directions in electrokinetics within microfluidics.
• To showcase advancements in manipulating complex fluids and analytes using electrokinetic phenomena.
• To illustrate the potential of electrokinetics in developing sophisticated analytical platforms.

Main Methods:

• Field-driven manipulation of droplets and emulsions, including Janus droplets.
• Electrokinetic injection techniques for precise sample plug generation.
• Control of EOF through surface chemistry, zeta potential engineering, and nanoscale patterning.
• Investigation of electrokinetic instabilities and electrically driven micromixing.
• Development of electrokinetic enrichment strategies like ion concentration polarization and stacking.

Main Results:

• Asymmetric interfacial structures enable unconventional transport modes in droplets.
• Sharply defined sample plugs are achieved for high-resolution separations.
• Non-Newtonian flow behavior is navigated for precise EOF control.
• Vortex-mediated perturbations enhance mixing efficiency in low-Reynolds-number flows.
• Trace analytes are selectively accumulated for improved detection sensitivity.

Conclusions:

• Electrokinetics is advancing towards integrated microfluidic platforms and hybrid powering schemes.
• These advancements promise to expand the capabilities of analytical chemistry and diagnostics.
• The field is poised to unlock new applications in previously inaccessible domains.