Three-dimensional splitting microfluidics.

Microfluidic systems with splitting structures are excellent for increasing emulsion production. However, traditional two-dimensional (2D) lithographic systems require complex modification of the microchannel surfaces and achieve only 2D splitting of the droplets. Herein, we present new glass capillary microfluidic devices that perform three-dimensional (3D) splitting of droplets. These devices are simply constructed using different structural glass capillaries as the collection microchannels of the droplet microfluidic systems. We demonstrate that the devices are able to produce a 3D split of both single emulsions and double emulsions into two and three portions, respectively. These emulsions, after the splitting process, still have high monodispersity. We believe that this new technique for 3D splitting could be widely used, not only in the field of microfluidics but also in chemical/biological applications (e.g., drug delivery, micro-dispersion, etc.).