A Self-Centering, Blade-Assisted, Electrowetting-Enabled Strategy for Precise Droplet Splitting on Open Digital...

Area of Science:

• Microfluidics
• Biotechnology
• Surface Science

Background:

• Droplet splitting on open digital microfluidic platforms faces challenges in complexity, automation, and operating conditions.
• Existing methods hinder the development and application of precise droplet manipulation.

Purpose of the Study:

• To develop a fully automated, precise, and stable droplet splitting method for open digital microfluidic platforms.
• To overcome the limitations of current droplet splitting technologies.

Main Methods:

• Utilized printed circuit boards with open-coplanar asymmetric electrodes and a slippery liquid-infused porous surface.
• Combined blade-assisted cutting with electrowetting-on-dielectric (EWOD) for droplet manipulation.
• Developed an active droplet position calibration method using a 3x3 electrode array and enveloping voltage strategy.

Main Results:

• Achieved accurate, stable, and repeatable automated droplet splitting with a positioning error < 0.06 mm (over 95% reduction).
• Identified critical cutting speed related to blade thickness for stable, equal-volume splitting.
• Determined square electrodes required the lowest splitting voltage (165 V at 0.3 mm blade thickness).
• Reduced droplet splitting time by 95.2% (from 5.57 s to 0.27 s) by increasing voltage to 400 V.

Conclusions:

• The proposed method offers a simple, highly automated, and precise solution for droplet splitting.
• This technology enhances efficiency and stability for applications in sample preparation and biochemical reactions.
• The system is practical for integration into portable droplet analysis systems.