Simultaneous Separating, Splitting, Collecting, and Dispensing by Droplet Pinch-Off for Droplet Cell Culture

Area of Science:

• Biotechnology
• Microfluidics
• Cell Biology

Background:

• Microfluidic systems offer precise control over small fluid volumes.
• Cell culture requires efficient methods for manipulation, concentration, and medium exchange.

Purpose of the Study:

• To develop and validate a microfluidic method for simultaneous droplet separation, splitting, collection, and dispensing.
• To demonstrate the application of this method for cell manipulation, including microalgal and mammalian cell suspensions.
• To assess the efficacy of medium exchange in spheroid droplets for 3D cell culture.

Main Methods:

• Utilizing aspiration and droplet pinch-off to manipulate cell suspension droplets.
• Conducting dimensional analysis and systematic parametric studies to understand droplet pinch-off regimes.
• Observing contact angle changes during aspiration to analyze force balance and droplet behavior.
• Investigating the influence of capillary number, Bond number, and Ohnesorge number on droplet pinch-off.

Main Results:

• Successful simultaneous separation, splitting, collection, and dispensing of cell suspension droplets.
• Demonstrated efficient medium exchange (>99%) for spheroid droplets without damage, highlighting potential for 3D cell culture.
• Identified three droplet pinch-off regimes determined by initial droplet size and aspiration flow rate.
• Quantified the role of capillary number in controlling dispensed droplet size, independent of Bond and Ohnesorge numbers.

Conclusions:

• The developed microfluidic droplet manipulation technique is effective for various cell types and applications.
• Precise control over dispensed droplet size is achievable by adjusting aspiration flow rate via capillary number.
• This method holds significant promise for advancing droplet cell culture, digital microfluidics, and other droplet-based technologies.