Observing Electrokinetic Janus Particle-Channel Wall Interaction Using Microparticle Image Velocimetry

Area of Science:

• Fluid dynamics
• Microparticle behavior
• Electrokinetics

Background:

• Understanding particle behavior near surfaces is crucial in microfluidics and materials science.
• Metallodielectric Janus particles exhibit unique properties due to their asymmetric composition.

Purpose of the Study:

• To investigate the hydrodynamic flow patterns around Janus particles adjacent to different wall types.
• To analyze the electrohydrodynamic effects and dielectrophoretic phenomena near conducting surfaces.

Main Methods:

• Employed three-dimensional/two-component microparticle image velocimetry (3D/2C-μPIV).
• Studied 15 μm diameter metallodielectric Janus particles.
• Examined particle interactions adjacent to insulating and conducting walls.

Main Results:

• Observed flow patterns agreed with existing models far from walls.
• Detected strong electrohydrodynamic flows near conducting walls at low frequencies, causing fluid injection.
• Demonstrated dielectrophoretic trapping of smaller polystyrene particles due to localized field gradients near the metallic hemisphere.

Conclusions:

• Janus particle hydrodynamics are significantly altered by proximity to conducting surfaces.
• Electrokinetic effects, including fluid injection and dielectrophoretic trapping, are prominent near conducting walls.
• These findings have implications for controlling microparticle manipulation in complex fluid environments.