Precise quantitative addition of multiple reagents into droplets in sequence using glass fiber-induced droplet coalescence.

Selective droplet coalescence using microfluidic systems.

We report a microfluidic approach, which allows selective and controlled 1 : 1, 2 : 1 or 3 : 1 droplet fusion. A surfactant-stabilized droplet with an interfacial surfactant coverage, Γ, of >98% will fuse spontaneously with a second droplet when Γ of the latter droplet is <16%. However, when Γ of the second droplet is ~66%, the two droplets will not fuse, unless they have previously been brough...

Electro-Coalescence of an Aqueous Droplet at an Oil–Water Interface with an Investigation of Secondary Droplets Formation

Coalescence and splitting of confined droplets at microfluidic junctions.

The ability to merge two droplets is an important component of droplet-based lab-on-a-chip devices, yet flow-induced coalescence is difficult to achieve due to long film drainage times compared with relatively short residence times. We examine droplet collisions at a simple microfluidic T-junction and characterize the response for a wide range of droplet sizes and speeds. We find that three pri...

Coalescence-Induced Jumping of Multiple Condensate Droplets on Hierarchical Superhydrophobic Surfaces

Coalescence-induced jumping of condensate droplets from a superhydrophobic surface with hierarchical micro/nanoscale roughness is quantitatively characterized. Experimental observations show that the condensate droplet jumping is induced by coalescence of multiple droplets of different sizes, and that the coalesced droplet trajectories typically deviate from the surface normal. A depth-from-def...

A fast and efficient microfluidic system for highly selective one-to-one droplet fusion.

Microdroplets in microfluidic systems can be used as independent microreactors to perform a range of chemical and biological reactions. However, in order to add new reagents to pre-formed droplets at defined times, to start, modify, or terminate a reaction, it is necessary to perform a controlled fusion with a second droplet. We describe and characterize a simple and extremely reliable techniqu...