Oscillatory flow for contactless particle trapping

Area of Science:

• Microfluidics
• Biophysics
• Fluid Dynamics

Background:

• Existing contact-free microfluidic trapping methods (optical, acoustic, dielectrophoretic) have limitations.
• These limitations include restricted trapping areas, complex tuning, and the need for specialized buffers.

Purpose of the Study:

• Introduce a novel contact-free trapping technique: the microfluidic oscillatory asymmetrical trap (MOAT).
• Overcome limitations of existing methods for stable particle trapping in microfluidic devices.

Main Methods:

• Investigated the MOAT phenomenon using experiments on a 3D-printed plane expansion chip.
• Conducted numerical simulations to analyze trapping behavior.
• Measured trapping efficiency and strength.

Main Results:

• Demonstrated stable, contact-free trapping using pressure oscillations in devices with streamwise geometric asymmetry.
• Observed trapping across diverse particle types (plastic beads to cell lines) and devices.
• Identified optimal conditions for trapping, enhanced by upstream inertial focusing.

Conclusions:

• The MOAT is a versatile and effective method for contact-free particle trapping in microfluidics.
• The phenomenon relies on oscillatory Reynolds number-dependent dynamics in asymmetric geometries.
• MOAT offers a promising alternative to existing trapping techniques, with broad applicability.