Miniaturizing chemistry and biology using droplets in open systems

Abstract

Open droplet microfluidic systems manipulate droplets on the picolitre-to-microlitre scale in an open environment. They combine the compartmentalization and control offered by traditional droplet-based microfluidics with the accessibility and ease-of-use of open microfluidics, bringing unique advantages to applications such as combinatorial reactions, droplet analysis and cell culture. Open systems provide direct access to droplets and allow on-demand droplet manipulation within the system without needing pumps or tubes, which makes the systems accessible to biologists without sophisticated setups. Furthermore, these systems can be produced with simple manufacturing and assembly steps that allow for manufacturing at scale and the translation of the method into clinical research. This Review introduces the different types of open droplet microfluidic system, presents the physical concepts leveraged by these systems and highlights key applications.

Poly(dimethylsiloxane) as a room-temperature solid solvent for photophysics and photochemistry

“…This property of PDMS made it widely popular for fabricating microfluidic devices that strongly impacted biological, biomedical, and engineering research at the turn of this century. 80–94…”

Fundamentals and Applications of Surface Wetting

“…Cell culture using open droplet microenvironments has grown recently, due to better accessibility to nutrients and treatments, easier splitting of droplets, and efficient creation of cell-based analytical methods or assays. 313 A recent review 314 has listed various strategies for cell patterning (e.g., the cell surface can be tuned in terms of topography, stiffness, and wettability) and some techniques (such as lithography, microcontact printing, stencils, traps, and droplet microfluidics). Due to the wettability patterned hydrophobic surfaces containing hydrophilic spots, multiple droplets are formed in arrays containing cells, as shown in Figure 14a.…”

On-chip droplet analysis and cell spheroid screening by capillary wrapping enabled shape-adaptive ferrofluid transporters

“…32,33 However, droplets moving on ferrofluidinfused surfaces still experience high interfacial drag, 34 and the exposure of droplets to an open environment is not feasible for bioanalytical applications where long-term cell incubation and in situ observations are needed. 35 Herein, we propose a ferrofluid transporter, which exhibits on-site droplet wrapping and transportation of droplets with high robustness in a silicone oil environment (Fig. 1A).…”

“…32,33 However, droplets moving on ferrofluid-infused surfaces still experience high interfacial drag, 34 and the exposure of droplets to an open environment is not feasible for bioanalytical applications where long-term cell incubation and in situ observations are needed. 35…”