Droplet coalescence by geometrically mediated flow in microfluidic channels

Microfluidic flow is geometrically mediated at a trifurcating junction allowing periodically formed, equally spaced out emulsion droplets to redistribute and fuse consistently. This is achieved by controlling the ratio between the droplet transport time across the trifurcating junction and the drainage time of the fluid volume separating the droplets t (r)/t (d). Three different microfluidic trifurcation geometries have been designed and compared for their droplet fusion efficiencies. Fusion of up to six droplets has been observed in these devices. The fusion of two droplets occurs when t (r)/t (d) is equal to 1.25 and the number of fused droplets increases with t (r)/t (d). When the junction length (d) is 216 mu m fusion of 2-6 six droplets are possible however when the junction length is increased to 360 mu m fusion of only two droplets is observed.