Fabrication of size-coded amphiphilic particles with a configurable 3D-printed microfluidic device for the formation of particle-templated droplets

Compartmentalizing an aqueous media into numerous nanoliter-scale droplets has substantially improved the performance of amplification assays. Particle-templated droplets or dropicles offer a user-friendly workflow for creating uniform volume compartments upon simple mixing of reagents and particles by using common laboratory apparatus. Amphiphilic shape-coded particles have been demonstrated to spontaneously hold aqueous droplets within hydrophilic cavities for multiplexed diagnostic assays. Here, we have proposed a configurable 3D-printed microfluidic device for the tunable fabrication of amphiphilic size-coded particles. The device was configured with multiple outlet tubings of different diameters and photomasks of variable slit lengths to fabricate a wide range of size-coded particles. We have fabricated >10 unique particle codes using a single reconfigurable device. The cross-sectional profile of the particles was further engineered by tuning the flow rate ratios of precursor streams to vary the inner and outer diameters of the particles and the thicknesses of the inner hydrophilic and outer hydrophobic layers. A range of cavity diameters and particle lengths enabled dropicle volumes of ∼1nL to ∼30nL. The fabricated particles were characterized by their ability to hold uniform droplet volumes and to orient themselves facing upwards or sideways in a well plate based on their aspect ratios.