A T-junction device allowing for two simultaneous orthogonal views: application to bubble formation and break-up

Area of Science:

• Fluid dynamics
• Microfluidics
• Optical measurement techniques

Background:

• T-junction microfluidic devices are widely used for fluid studies.
• Measuring multi-component velocity fields in microfluidics presents challenges.
• Simultaneous orthogonal plane velocity measurements are often difficult to achieve.

Purpose of the Study:

• To propose a novel T-junction microfluidic device design for simultaneous in-plane velocity component measurement in two orthogonal planes.
• To enable the measurement of all three velocity components at the intersection of these planes.
• To facilitate 3D velocity field reconstruction and analysis of interfacial phenomena.

Main Methods:

• Development of a novel T-junction microfluidic configuration.
• Implementation of a dedicated optical setup for simultaneous dual-plane imaging onto a single camera sensor.
• Utilizing a commercial micro-particle image velocimetry (µPIV) system for velocity acquisition.
• Employing phase averaging during bubble formation and breakup for velocity measurement.

Main Results:

• Successful simultaneous measurement of velocity components in two orthogonal planes within the T-junction.
• Demonstration of the ability to obtain all three velocity components at the intersection.
• Characterization of bubble formation and breakup dynamics.
• Identification of systematic error dominated by measurement slice thickness, reducible with confocal microscopy.
• Feasibility of full 3D velocity field reconstruction through plane sweeping.
• Extraction of bubble meniscus principal curvatures for Laplace pressure determination.

Conclusions:

• The novel T-junction design effectively enables simultaneous multi-plane velocity measurements in microfluidic systems.
• This approach provides access to 3D velocity fields and interfacial properties like Laplace pressure.
• Confocal microscopy integration offers a pathway to enhance measurement accuracy by reducing slice thickness.