Droplet Velocity Measurement Based on Dielectric Layer Thickness Variation Using Digital Microfluidic Devices

Area of Science:

• Microfluidics
• Biotechnology
• Materials Science

Background:

• Interdisciplinary research on miniaturized systems for chemical and biological analyses is growing.
• Digital microfluidic biochips (DMFBs) offer inexpensive, fast, and reliable biochemical assays for research and diagnostics.
• Dielectric layers are crucial for actuating microliter droplets in DMFBs via electrowetting-on-dielectric (EWOD).

Purpose of the Study:

• To investigate the advantages of parafilm, polytetrafluoroethylene (PTFE), and ethylene tetrafluoroethylene (ETFE) as dielectric layers in DMFBs.
• To fabricate and test a simple DMFB device using these materials.
• To determine the threshold actuation voltage for various dielectric materials and thicknesses.

Main Methods:

• Fabrication of a digital microfluidic device using parafilm, PTFE, and ETFE as dielectric layers.
• Testing the OpenDrop device with a single-plate system for microliter droplet transport in bioassay operations.
• Measuring changes in contact angle and droplet velocity under applied actuation voltage.

Main Results:

• Successful fabrication of a DMFB device yielding good results.
• Demonstrated changes in contact angle and droplet velocity with applied actuation voltage for the tested dielectric materials.
• Determined a threshold actuation voltage of 190 V for 10–13 μm dielectric layers in open-plate DMFBs.

Conclusions:

• Parafilm, PTFE, and ETFE are suitable dielectric materials for DMFB fabrication.
• The proposed fabrication methods enable effective droplet manipulation for bioassay applications.
• The study provides key insights into the electrowetting behavior of different dielectric materials in DMFBs.