Microfluidic gradient device for simultaneously preparing four distinct types of microparticles.

Preparing monodisperse, reproducible and functionally sophisticated microparticles is challenging but important for biomedical applications. Droplet microfluidics is a microparticle generation method that can precisely control the geometry and composition of microparticles. Droplet microfluidics generally produces only one type of microparticle at a time. Here, we report a simple and controllable method to simultaneously prepare four distinct types of microparticles by combining droplet generation with a gradient generator. The method can be more widely applied and with higher productivity than other microparticle generation methods due to the integration of dispersed phases which paves the way for the application to regenerative medicine. Different sizes, heterogenous and anisotropic microparticles are generated by manipulating the poly(lactic-co-glycolic acid) concentration gradient, the poly(ε-caprolactone)/poly(lactic-co-glycolic acid) ratio gradient, and the dimethyl carbonate/dichloromethane ratio gradient. This straightforward preparation of microparticles will promote their application in drug delivery agents, identifiers for biological assays, microsensors and tissue engineering.