Focusing of Particles in a Microchannel with Laser Engraved Groove Arrays

Area of Science:

• Microfluidics
• Biomedical Engineering
• Laser-based Microfabrication

Background:

• Continuous microfluidic focusing is crucial for particle manipulation in various scientific fields.
• Existing methods often face limitations in efficiency and applicability to diverse particle types.

Purpose of the Study:

• To develop and investigate a novel microfluidic device for continuous particle focusing.
• To explore the efficacy of laser-engraved microgrooves in particle and cell manipulation.
• To understand the underlying fluid dynamics governing the focusing mechanism.

Main Methods:

• Fabrication of microchannels with precisely engraved glass grooves using femtosecond (fs) laser ablation.
• Experimental investigation of particle (polystyrene) and cell (C2C12) focusing at low Reynolds numbers (Re < 1).
• Numerical simulations to elucidate the role of secondary flows induced by microgrooves.

Main Results:

• Laser-engraved grooves successfully directed particles and cells to the microchannel center.
• Secondary flows generated by grooves are key to lateral particle displacement.
• Focusing efficiency depends on groove angle, spacing, and particle sedimentation rate.
• Demonstrated selective focusing of micrometer particles based on size-dependent displacement.

Conclusions:

• Groove-embedded microchannels offer an effective platform for continuous particle and cell focusing.
• The demonstrated technology has potential for applications in cell sensing and nanoparticle separation.
• Femtosecond laser engraving provides a versatile method for fabricating functional microfluidic devices.