Trapping a moving droplet train by bubble guidance in microfluidic networks

Area of Science:

• Microfluidics
• Biochemistry
• Fluid Dynamics

Background:

• Microfluidic devices enable long-term observation of biochemical reactions within droplets.
• Current droplet trapping methods have a limited flow rate range for uniform trapping.

Purpose of the Study:

• To propose and evaluate a novel bubble-guided trapping method for microfluidic droplets.
• To improve the range and uniformity of droplet trapping in microfluidic devices.

Main Methods:

• Comparison of bubble-free and bubble-guided droplet train flow behaviors.
• Analysis of trapping modes under identical two-phase flow rates.
• Leveraging bubble properties (non-coalescence, flow resistance) for guided trapping.

Main Results:

• Bubble-guided trapping significantly broadens the two-phase flow rate range for uniform droplet trapping.
• The uniformity of the trapped droplet array is substantially improved compared to bubble-free methods.
• Both methods exhibit four trapping modes, but bubble-guided trapping enhances uniform trapping outcomes.

Conclusions:

• The bubble-guided trapping method offers a significant advancement for passive droplet storage in microfluidic applications.
• This technique enhances the stability and reliability of droplet arrays for biochemical analysis.
• The findings contribute to the broader applicability of microfluidic platforms for long-term droplet manipulation.