Programmable Generation of Droplet Array with Volumetric Gradient by Modulating the Smearing Velocity

Area of Science:

• Microfluidics
• Materials Science
• Biotechnology

Background:

• Droplet-array microreactors are crucial for high-throughput, low-consumption microfluidic platforms.
• Femtosecond laser engraving creates hydrophilic sites on hydrophobic substrates for droplet manipulation.

Purpose of the Study:

• To develop a smearing-driven droplet array dispensing platform for programmable generation of droplet arrays with tunable volume gradients.
• To enable real-time control of droplet volume distribution and reduce reliance on complex equipment.

Main Methods:

• Utilizing a smearing-driven platform with hydrophilic sites engraved by femtosecond laser.
• Implementing a rotational platform to exploit radial velocity for generating volume gradients.
• Programming smearing velocity and utilizing radial position for volume control.

Main Results:

• Demonstrated a 100-fold increase in droplet volume with tunable gradients.
• Achieved predictable scaling of droplet volume with smearing velocity and radial position.
• Decoupled droplet volume from fixed pattern dimensions, simplifying gradient programming.

Conclusions:

• The developed platform provides a versatile, resource-efficient solution for droplet-based microfluidics.
• Potential applications include point-of-care diagnostics, combinatorial assays, and high-throughput screening.
• The system eliminates dependencies on complex external facilities for gradient generation.