Dielectrowetting manipulation for digital microfluidics: creating, transporting, splitting, and merging of droplets

Abstract

Generating, splitting, transporting, and merging droplets are fundamental and critical unit operations for digital (droplet-based) microfluidics. State-of-the-art digital microfluidics performs such operations commonly using electrowetting-on-dielectric (EWOD) in the typical configuration of two parallel channel plates. This paper presents such operations using dielectrowetting (derived from liquid dielectrophoresis), not EWOD, with an array of interdigitated electrodes. The major and unique feature is that the present droplet manipulations are effective for conductive (water with/without surfactant) and non-conductive (propylene carbonate) fluids. An equally important aspect is that the manipulations are performed in an open space without the covering top plate. This behavior is attributed to the intrinsic nature of dielectrowetting to generate stronger wetting forces than EWOD (with the ability to achieve complete wetting with contact angle = 0° to form a thin film). Using dielectrowetting, micro-droplets of various volumes are created from a large droplet and transported. Splitting a single droplet as well as multiple droplets and merging them are also achieved, even when the droplets are smaller than the electrode pads. The above splitting, transport, and merging operations are effective for propylene carbonate as well as DI water with/without surfactant, though the creating operation is proven only for propylene carbonate at this moment. All the above manipulations are successfully carried out on a single plate, which not only simplifies the structure and operation procedure, but could also eliminate the restriction to the volume of fluid handled.

Investigation of droplet coalescence propelled by dielectrophoresis

“…Schwartz et al produced a proof‐of‐concept of droplet translation and fusion on a reaction surface. Recently, Geng et al performed translation, merging, splitting, and generation of droplets by dielectrophoresis force over a planner array of electrodes. Zeng and Korsmeyer performed numerical simulation to coalesce droplets of dielectric material on electrode arrangement similar to EWOD.…”

Field‐Controlled Electrical Switch with Liquid Metal

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tension, geometry, and fluidic instabilities through spatial control of interfacial energies.Several examples of digital microfluidics and liquid-based switches exist in the literature, though most demand high voltages for conventional electrostatic techniques [7][8][9][10][11] or activate under outside influences such as environmental corrosion of oxide. [12] Referring to Figure 1, lowvoltage-controlled coalescence and separation are accomplished with a pair of liquid metal (LM) droplets immersed in a basic aqueous electrolytic solution.

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Magnetoresponsive Surfaces for Manipulation of Nonmagnetic Liquids: Design and Applications

“…[27][28][29][30] It is also possible to use magnetic field for droplet operation in digital microfluidics. [27][28][29][30] It is also possible to use magnetic field for droplet operation in digital microfluidics.…”

“…Traditional digital microfluidics use electrowetting for complex manipulation of droplets. [27][28][29][30] It is also possible to use magnetic field for droplet operation in digital microfluidics. [56,90,93,108] Biswas et al fabricated a stretchable elastomeric film embedded with steel balls or magnetic particles for digital [102] Copyright 2015, the Authors.…”