A simple capillary-based open microfluidic device for size on-demand high-throughput droplet/bubble/microcapsule...

Area of Science:

• Microfluidics
• Materials Science
• Chemical Engineering

Background:

• Droplet generation is crucial for microfluidic applications.
• Existing methods often require complex fabrication and precise control.
• A need exists for simple, robust, and versatile droplet generation systems.

Purpose of the Study:

• To develop an easily-established capillary-based open microfluidic device (COMD) for on-demand generation of monodisperse droplets.
• To demonstrate control over droplet size, volume, and generation frequency.
• To explore the potential for high-throughput applications.

Main Methods:

• A capillary is positioned near a flat surface with a controlled gap distance.
• A continuous phase remains static, while a dispersed phase is pumped through the capillary.
• Droplet formation is controlled by gap distance, fluid flow, and surface properties.

Main Results:

• Monodisperse droplets, bubbles, and microcapsules (10-300 μm) were generated with controllable frequency (1-1000 Hz).
• Droplet size is primarily determined by gap size at low flow rates and increases with flow rate at higher rates.
• Droplet type can be tuned by fluid selection and surface modifications.
• In-parallel integration of capillaries enables high-throughput generation.

Conclusions:

• The COMD is a simple, robust, and flexible microfluidic device for size-on-demand droplet generation.
• It requires no complex microfabrication, making it accessible for common laboratories.
• The device has significant potential for droplet-based assays and industrial emulsification.