An ultra-low voltage microfluidic device for manipulating droplets of liquid by inducing Marangoni stress therein includes a plurality of smart-polymer electrodes having films of smart polymer exposed at their surfaces. The surface of the smart polymer becomes hydrophobic or hydrophilic in response to different electromagnetic potentials. The smart polymer is reversibly oxidized by applying an electrical potential such that the smart polymer acquires a positive electrical charge. The oxidized smart polymer is reduced by applying an electrical potential such that it loses its positive electrical charge. The smart polymer is doped with a chemical compound having a negatively-charged end and a long-chain hydrophobic tail. The smart polymer is a polypyrrole and the dopant is a dodecylbenzene sulfonate. The microfluidic device includes a plurality of individually-addressable control electrodes, each of which is electrically-connected with smart-polymer electrodes. Droplets are transported, cut, or mixed by selectively applying electrical potential to individual electrodes.

Full Patent: Marangoni Stress-Driven Droplet Manipulation On Smart Polymers For Ultra-Low Voltage Digital Microfluidics