Droplet splitting and merging

Mixing strategies for droplets formed at low aspect ratio/split and merge mixing... 

Digital microfiuidics is based upon the micromanipulation of discontinuous fluid droplets within a reconfigurable network. Complex instructions can be programmed by combining the basic operations of droplet formation, translocation, splitting, and merging. 

Droplet Traffic in Microfluidic Networks Traffic of droplets (without splitting and merging) in a dual network can also be simulated in a similar method, which contains transport channels for droplet transport and bypass channels that cannot be accessed by droplets. Figure 1 shows three recently proposed devices for droplet traffic analysis a reversible encoding loop (Fig. la), a bypassed Y-junction for symmetric... 

The development of truly versatile chips for analytical, synthetic and biological chemistry will require not only the understanding of the flow in networks, but also the development of modules for active control over the flow, merging, splitting and above all, formation of droplets. Below we review the field of active control over formation of droplets and provide an example of a microfluidic droplet-on-demand system. 

Figure 6. Merge, mix, split, and transport were the main manipulation steps used for on-chip droplet-based DNA purification. The system was able to extract genomic material from dilute raw cell samples by using the actuation of magnetic microparticles within the droplet using a matrix of coils [50],...

Digital Microfluidics, Fig. 3 1-4) Droplet formation sequence gray squares depict energized electrodes. (A-D) Droplet splitting. (E) and (F) Droplet merging. See text for details... 

Both platforms for droplet microreactors require the following key functimis for manipulating droplets droplet formation, droplet transport, mixing inside droplets, droplet merging, and droplet splitting. In the following, the basic methods for obtaming these functions are discussed. 

The merging of different sized droplets showing different velocities to single droplets has been demonstrated successfully [151]. In the same work, the controlled splitting of droplets at a channel branching point has been shown. Using a similar method, the formation of droplet emulsions with controlled volume fractions and drop sizes has been realized [156]. 

However, all these advantages raise a new set of fluid dynamical problems related to the deformable interface of the droplets the need to take into account interfacial tension and its variations and the complexity of singular events such as merging or splitting of drops. 

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