Oscillating Dispersed-Phase Co-Flow Microfluidic Droplet Generation: Effects on Jet Length and Droplet Size

Droplet-based microfluidics have emerged as versatile platforms offering unique advantages in biology and chemistry. Although there is adequate control on size and monodispersity, most conventional microfluidic techniques cannot generate more than one droplet size at a time in a continuous and high-throughput manner. Moreover, the widely used co-flow microfluidic droplet generation technique is bottlenecked with droplet polydispersity at high throughputs due to the transition from a more-stable dripping regime to an instable jetting regime at high d-phase flow rates. We applied nozzle oscillatory motion to generate an axial shear gradient as well as inducing an additional transverse drag force. We hypothesized that the combined effects of axial and transverse drags can be used for overcoming the aforementioned limitations of co-flow systems. Nozzle oscillation effect was studied in both dripping and jetting regimes to generate repeatable patterns of multi-size monodisperse droplets and jet length reduction in different biphasic systems, respectively.