Trapping and collection of uniform size droplets for nanoparticle synthesis

This paper presents a simple and fast method for droplet trapping and collection and demonstrates nanoparticle synthesis inside these trapped droplets. Since droplet trapping is size-dependent, droplets having various sizes caused by unstable inlet flows can be eliminated. Moreover, the new droplet substitutes the previous one, so we can keep the up-to-date contents of droplets at all times. All trapped droplets can be simply collected at the outlet. We had demonstrated the synthesis of iron oxide nanoparticles inside droplets and collection of them from the device. Due to its simplicity and high efficiency for selective trapping and collection, this method can become one of the key essentials in droplet-based microfluidic assays.