Creating monodispersed droplets with electrowetting-on-dielectric step emulsification

Abstract

Monodisperse droplets are important in drug screening, and cell-based and biochemical research. However, conventional methods for creating droplets, such as co-flow, T-junction and flow-focusing, have poor monodispersity because of fluctuations in the flow rate. Because step emulsification is based on the principle of Laplace pressure, it is insensitive to the flow rate and yields a constant and high monodispersity. In the present study, we combine electrowetting and step emulsification to reduce the negative influence of flow-rate fluctuations and to prepare highly monodisperse droplets. We demonstrate that the flow rate and voltage applied to the droplets can independently influence the droplet size. This method has great potential in chip-based bioanalysis and cell-based studies where highly monodisperse droplets are needed.

Precise Control of Microcapillary Size in Microcapillary Films by Liquid‐Assisted Extrusion

“…[17] Huang et al applied MCFs into droplet microfluidics and had produced emulsions by step-emulsification and multilayered droplets by electrocoalescence. [18,19] Apart from microfluidic applications, Gill et al used MCFs to quantify the extent of micromixing and performed continuous flow chemical reactions based on experiments and numerical simulations. [11] Donmez et al combined MCFs with smartphone to realize label-free quantitation of bacteria.…”

Improved Size Uniformity of Microcapillaries in Microcapillary Films by Separate Gas Injection

“…MCFs are used as droplet generators to produce emulsions by step-emulsification [32,33] and multilayered droplet generators by electro-coalescence. [34] The dimensional parameters of MCFs, such as the microcapillary distance, diameter, and wall contact angle, critically affect the droplet diameter and generation frequency.…”