Serial microfluidic device for micro droplet trapping and pairing

We propose a serial flowing microfluidic system for droplet generation along with a sequential trapping and pairing of micro-droplets. This device consists of three different functional regions: a flow focusing droplet generator; a single droplet trap region; and a pairing region. Our design is based on the principle of exploiting hydrodynamic resistance of the columnar structure in the microfluidic channel. By adjusting the flow rate and the fluid pressure inside the trapping area, the droplet trapping was precisely executed. The proposed method would continuously trap the droplets in the trapping area and when the reverse flow is applied, the droplet would be released and would enter the pairing chamber where it would be held until another droplet of different liquid to combine with it. Second droplet travels in the reverse flow direction and would be trapped in the pairing chamber to combine with first droplet.