Efficient Micro/Nanoparticle Concentration using Direct Current-Induced Thermal Buoyancy Convection for Multiple...

Area of Science:

• Microfluidics
• Biophysics
• Materials Science

Background:

• Thermal-based microparticle focusing is attractive for its noninvasive nature but limited by complex heating systems and low velocities.
• Existing methods often struggle with complicated fluid heating and slow particle manipulation, hindering broader applications.

Purpose of the Study:

• To develop a flexible and efficient microparticle focusing approach using direct current-induced thermal buoyancy convection.
• To overcome limitations of existing thermal focusing techniques by simplifying the system and increasing particle velocity.

Main Methods:

• Utilized indium tin oxide (ITO) microheaters isolated from fluids by a glass slide to generate thermal buoyancy convection.
• Demonstrated static and continuous particle focusing of various microparticles (silica, yeast, polystyrene, copper) in both conducting and insulating solutions.
• Investigated selective and simultaneous focusing of mixed particle sizes by adjusting voltage and microheater configurations.

Main Results:

• Achieved efficient static and continuous particle focusing in diverse media, including conducting and insulating solutions.
• Demonstrated flexible manipulation of microparticles, including selective focusing of heavier particles and simultaneous concentration of mixtures.
• Successfully applied the device for wear measurement by focusing nanocopper particles in hydraulic oil.

Conclusions:

• The proposed DC-induced thermal buoyancy convection method provides a flexible, efficient, and noninvasive approach for microparticle focusing.
• This technique enables both static and continuous particle manipulation in various liquid media, broadening on-chip application possibilities.
• The device shows promise for real-time applications such as machine wear monitoring.