Simple Method to Generate Droplets Spontaneously by a Superhydrophobic Double-Layer Split Nozzle

Area of Science:

• Microfluidics
• Surface Science
• Materials Science

Background:

• Traditional droplet generation devices face challenges including complex fabrication, difficult droplet separation, and low transfer accuracy.
• Existing methods often require intricate photolithography processes, increasing costs and complexity.

Purpose of the Study:

• To introduce a novel low-adhesion superhydrophobic double-layer split nozzle (SDSN) for spontaneous droplet generation.
• To demonstrate precise control over droplet volume and efficient liquid transfer with minimal residue.

Main Methods:

• Fabrication of the SDSN using conventional mechanical drilling, chemical etching, and low surface energy modification.
• Utilizing interfacial tension within micro-holes to drive spontaneous droplet snap-off.
• Adjusting micro-hole size (100-500 μm) to control droplet volume (0.65-1.75 ± 0.007 μL).

Main Results:

• Achieved stable, highly consistent micrometer-scale droplets through spontaneous snap-off.
• Demonstrated precise droplet volume control by adjusting nozzle hole size.
• Enabled efficient droplet transfer without liquid residue, improving accuracy and reagent saving.

Conclusions:

• The SDSN offers a cost-effective, simpler alternative to traditional droplet generation devices, eliminating the need for photolithography and post-processing.
• The device exhibits excellent stability, unaffected by external condition fluctuations.
• This technology holds significant potential for advancements in spontaneous droplet generation, liquid transport, and digital microfluidic systems.