Droplet manipulation on an adjustable closed-open digital microfluidic system utilizing asymmetric EWOD

Area of Science:

• Microfluidics
• Surface Science
• Biotechnology

Background:

• Closed-open digital microfluidic (DMF) systems integrate benefits of both designs.
• Current systems face scalability issues due to differing electrode structures in closed and open regions.

Purpose of the Study:

• To develop an adjustable, scalable, and cost-effective closed-open DMF platform.
• To investigate droplet manipulation at the closed-open boundary and optimize platform parameters.
• To demonstrate the platform's utility in biological sample processing and detection.

Main Methods:

• Utilized modified slippery liquid-infused porous surfaces (SLIPS) with asymmetric electrowetting on dielectric (AEWOD).
• Employed consistent printed circuit board (PCB) electrode arrays and a floating potential top plate.
• Investigated effects of voltage, plate spacing, switching intervals, and driving strategies on droplet manipulation.
• Analyzed top plate geometry and bevel angle for boundary droplet movement.

Main Results:

• Achieved a low-cost, scalable closed-open DMF system with consistent electrode structures.
• Identified optimal plate spacings (340-510 μm) in the closed region.
• Determined that a thin top plate with a ~4° bevel facilitates droplet movement at the boundary.
• Successfully performed protein staining and developed a smartphone app for protein concentration detection.

Conclusions:

• The developed adjustable closed-open DMF platform overcomes scalability challenges.
• The platform enables precise droplet control and efficient biological assays.
• This system offers significant potential for real-time biological sample processing and detection applications.