Size-tunable droplet microfluidic system using an on-chip microfluidic peristaltic pump

Droplet microfluidics has become widely employed in various chemical and biological analyses, by offering the capacity of high-efficiency generation of miniature droplets in accurate sizes and precise concentrations. In this article, a size-tunable droplet microfluidic system has been first developed, which includes an on-chip microfluidic peristaltic pump. In particular, both the sizes and frequencies of the generated droplets can be fine-tuned without requirement of changing the geometrical design of the microfluidic chip itself. By choosing proper parameters as driving voltage and frequency of the peristaltic pump, the desired droplet length (from 81.5 µm to 345.5 µm) and generation frequency can be easily obtained. Due to the on-chip design of the micropump, the size-tunable droplet microfluidic system has tiny dead volume as low as 1 μL. Moreover, less than 200nL reagent was wasted before getting into a stable droplet generating state, showing potential in the applications of capsulation of rare objects in small-volume sample and isovolumetric isolation for precise analysis.