Tunable Droplet Manipulation and Characterization by ac-DEP.

Area of Science:

• Microfluidics
• Dielectrophoresis
• Particle Manipulation

Background:

• Dielectrophoresis (DEP) is a powerful technique for manipulating microparticles and droplets using non-uniform electric fields.
• Existing DEP devices often lack tunability and precise control over particle and droplet behavior.

Purpose of the Study:

• To present a novel AC-dielectrophoretic (DEP) device for tunable manipulation and characterization of particles and droplets.
• To demonstrate the device's capability for size-based particle separation and type-based droplet separation.
• To investigate the frequency-dependent behavior of particles and droplets within the microfluidic device.

Main Methods:

• Fabrication of a microfluidic chip with embedded microelectrodes and asymmetric orifices.
• Application of AC electric fields to induce DEP forces for particle and droplet manipulation.
• Experimental investigation of particle/droplet manipulation under varying electric field strengths and frequencies.
• Comparison of experimental results with theoretical simulations.

Main Results:

• Demonstrated tunable manipulation and separation of particles by size using AC-DEP.
• Successfully separated ionic liquid (IL) droplets from oil droplets of the same size based on type.
• Observed frequency-dependent lateral migration of IL droplets, correlating with the Clausius-Mossotti factor.
• Validated experimental findings with theoretical simulations.

Conclusions:

• The novel AC-DEP device offers tunable control over particle and droplet manipulation and characterization.
• Adjusting AC electric field strength and frequency enables specific separation of particles and droplets by size and type.
• The device provides a method for identifying critical frequencies and characterizing droplets in microfluidic systems.