A new microfluidic device for forma-tion and switching of micro-droplets

This study presents a new microfluidic chip capable of generating tunable and uniform droplets. The generated micro-droplets can be further switched to different directions for further sorting applications. A pneumatic air chamber called controlla-ble moving-wall structures was designed near the flow-focusing microchannels to locally accelerate the sheath flow velocity and increase the shear force without ad-justing syringe pumps. When supplied compressed air to both of the moving-wall structure, the micro-droplets diameters ranging from 31.4 to 146.2 μm with coeffi-cient of variation less than 5.39% could be precisely generated. When supplied com-pressed air to only one moving wall structure, micro-droplets departure angle can be controlled form 0⁰ to 53.5⁰. The development of the chip may be used for emulsion applications.