We demonstrated an effective method for producing poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) arched nanowires, which are used as stretchable interconnects. Three-dimensional PEDOT:PSS arched wires with high stretchability were fabricated by a simple, inexpensive fountain pen lithography (FPL) technique. The grown PEDOT:PSS wires showed superior stretchable behavior: the wire conductance was only decreased by less than 0.5% when the horizontal strain increased by up to 80%. Using a steaming treatment with a co-solvent of ethanol and water, the wire conductivity was enhanced from 2 S m(-1) to 1.57 x 10(3) S m(-1), without undesirable deformation or collapse of the wires. The conductivity enhancement is attributed to enhancement in the inter-PEDOT chain charge transport, resulting from a conformational change of PEDOT and PSS chains by sequential solvation of PEDOT and PSS chains near the wire surface. (C) 2014 Elsevier B.V. All rights reserved.