Transportation of a liquid droplet at ultra-low voltages by tunable wetting on conjugated polymer electrodes

This paper presents the experimental results on the controlled transportation of a liquid droplet on dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)) electrodes for ultra-low voltage digital microfluidics applications. The PPy(DBS) surface fabricated by the electropolymerization method exhibits a tunable wettability upon reduction and oxidation at low voltages (-0.9~0.6V). By utilizing an asymmetric change of surface wettability on patterned PPy(DBS)-coated electrodes, lateral, controllable transportation of liquid droplets on the PPy(DBS) surface with underlying electrodes was successfully demonstrated with low voltages (<; 1V). The actuation behavior of the liquid droplet during the transportation was characterized and analyzed.