Separating large microscale particles by exploiting charge differences with dielectrophoresis

Area of Science:

• Electrokinetics
• Microfluidics
• Particle Separation

Background:

• Electrophoresis (EP) is limited in separating larger microparticles (>5 µm) due to low electrophoretic mobilities.
• Dielectrophoresis (DEP) offers an alternative by utilizing particle polarization in nonuniform electric fields.

Purpose of the Study:

• To characterize and separate larger microparticles using insulator-based dielectrophoresis (iDEP).
• To demonstrate iDEP's capability in exploiting charge differences for particle separation, particularly for particles with similar physical properties.

Main Methods:

• Utilized microdevices for insulator-based dielectrophoresis (iDEP) to expose microparticles to DEP, EP, and electroosmotic (EO) forces simultaneously.
• Characterized microparticle electrokinetic behavior using velocimetry and dielectrophoretic capture assessments.
• Performed dielectropherogram separation of 10 µm polystyrene microparticles.

Main Results:

• Successfully separated two distinct types of 10 µm microparticles in under 80 seconds using iDEP.
• Demonstrated that iDEP can separate particles of identical size, shape, and material by exploiting minor variations in surface charge.
• Achieved distinct elution peaks, indicating successful enrichment of separated particle types.

Conclusions:

• Insulator-based dielectrophoresis (iDEP) provides an effective method for separating larger microparticles based on charge differences, surpassing EP limitations.
• This technique holds potential for assessing and separating biological cells with subtle variations in surface electrical charge.
• iDEP offers a versatile platform for microparticle characterization and separation in microfluidic devices.