Dielectrophoretic manipulation of suspended submicron particles

Area of Science:

• Microfluidics
• Nanotechnology
• Biophysics

Background:

• Microparticle manipulation is crucial for various applications.
• Dielectrophoresis offers label-free particle manipulation.
• Radiofrequency (RF) fields enable dielectrophoresis in aqueous solutions.

Purpose of the Study:

• To fabricate and test micro-electrode systems for microparticle trapping and aggregation.
• To investigate the use of RF electric fields for negative dielectrophoresis.
• To explore the potential of dielectrophoretic devices for submicron particle separation.

Main Methods:

• Fabrication of planar and 3D multi-electrode systems using integrated circuit (IC) technology.
• Application of radiofrequency (RF) electric fields to induce negative dielectrophoresis.
• Observation and trapping of microparticles (down to 100 nm) using confocal fluorimetry.

Main Results:

• Successfully trapped and aggregated microparticles down to 100 nm in dielectrophoretic microfilters and field cages.
• Theoretically, particles down to 35 nm should be trappable in micron field cages.
• Ohmic heating in RF fields can induce liquid streaming, aiding pumping but hindering trapping by increasing Brownian motion.

Conclusions:

• RF electric fields are effective for trapping microparticles using dielectrophoresis.
• Dielectrophoretic microdevices show promise for sensitive separation of submicron particles.
• Controlling liquid streaming induced by Ohmic heating is key for optimizing Brownian pumps for particle separation.