Scalable attoliter monodisperse droplet formation using multiphase nano-microfluidics

Abstract

We demonstrate a robust method to produce monodisperse femtoliter to attoliter droplets by using a nano-microfluidic device. Two immiscible liquids are forced through a nanochannel where a steady nanoscopic liquid filament forms, thinning close to the nanochannel exit to a microchannel due to the capillary focusing. When the nanoscopic filament enters the microchannel, monodisperse droplets are formed by capillary instability. In a certain range of physical parameters and geometrical configurations, the droplet size is only determined by the nanochannel height and independent of liquid flow rates and ratios, surfactants, and continuous phase viscosity. By using nanochannels with a height of 100-900 nm, 0.4-3.5 lm diameter droplets (volume down to 30 aL) have been produced. The generated droplets are stable for at least weeks.

Interfacial Phenomena and Fluid Control in Micro/Nanofluidics

“…119 Using a similar concept, Shui et al reported two-phase junctions in nanofluidic channels for small-droplet formation. 122 Recently, an improved version of the pressure-driven flow method, where solenoid valves are installed for pressure regulation and pressure control is realized with a 10-ms temporal resolution, was reported. 123 In spite of the various attractive features of nanofluidic systems, fundamental technologies such as pressure-driven flow regulation and switching are relatively immature.…”

Microfluidic Induced Controllable Microdroplets Assembly in Confined Channels

“…Combination of fluidics and microstructures has enabled wide applications in optical, chemical and biomedical research [11][12][13][14][15]. Microfluidics has been demonstrated to be a powerful platform with the capability of creating numerous monodispersed soft particles (bubbles or droplets) with controllable size, shell thickness, shapes, compartments and chemical compositions [16][17][18][19]. Moreover, in the microfluidic device, the fluidic properties and flow profiles, the microstructure size and shapes could be tuned properly.…”

Monodisperse bubbles and droplets for medical applications

“…The microfluidic nano-microchannel design reported by Shui et al 194 was adapted here, see Fig. 8.2A.…”

“…Smaller monodisperse droplets can be produced at a nano-microchannel interface where the dispersed phase is forced through the nanochannel and when it reaches the microchannel, it destabilizes due to capillary instability and breaks up into monodisperse droplets 191,192 . It was shown that the droplet size scales linearly with the height of the nanochannel 191,193 and it was also shown that it is feasible to produce monodisperse droplets with sizes down to 400 nm 194 . The production rates for a single nano-microchannel interface were shown to be limited to approximately 10 3 droplets per second 193 .…”