Droplet formation behavior in a microfluidic device fabricated by hydrogel molding

We describe the behavior of droplet formation within 3D cross-junctions and 2D T-junctions with various cross-sectional geometries that were manually fabricated using the hydrogel-molding method. The method utilizes wire-shaped hydrogels as molds to construct 3D and 2D microchannel structures. We investigated the flow patterns and droplet formation within the microchannels of these microfluidic devices. Despite being fabricated manually, the microchannels with 3D cross-junctions and 2D T-junctions were reproducible and formed highly monodispersed droplets. Additionally, the sizes of the droplets formed within the microchannels could be predicted using an experimental formula. This technique of droplet formation involves the use of a device fabricated by hydrogel molding. This method is expected to facilitate studies on droplet microfluidics and promote the use of droplet-based lab-on-a-chip technologies for various applications.