Integrated microfluidic system capable of size-specific droplet generation with size-dependent droplet separation

Droplet-based microfluidics is receiving much attention in biomedical research area due to its advantage in uniform size droplet generation. Our previous results have reported that droplet size plays an important role in drug delivery actuated by flagellated bacteria. Recently, many research groups have been reported the size-dependent separation of emulsion droplets by a microfluidic system. In this paper, an integrated microfluidic system is proposed to produce and sort specificsized droplets sequentially. Operation of the system relies on two microfluidic transport processes: initial generation of droplets by hydrodynamic focusing and subsequent separation of droplets by a T-junction channel. The microfluidic system is fabricated by the SU-8 rapid prototyping method and poly-di-methyl-siloxane (PDMS) replica molding. A biodegradable polymer, poly-capro-lactone (PCL), is used for the droplet material. Using the proposed integrated microfluidic system, specific-sized droplets which can be delivered by flagellated bacteria are successfully generated and obtained.