Conducting polymers are important materials for flexible optoelectronics and printed circuit applications. In our work, we quantify the contributions of wrinkles and cracks toward the resistance changes observed in strained PEDOT:PSS films. We demonstrate a peculiar ‘strain memory effect’ in terms of the history dependence of wrinkles array when the film subject to cyclic strain. We also study the swelling kinetics and swelling-induced charge transport in PEDOT:PSS thin films having different PEDOT to PSS ratio. Finally, we nanostructure mechanical cracks to design ultra-sensitive vapor sensors. The different extent of response to alcohol vapors and humidity is attributed to the dominance of surface ionic conduction process in the nanostructured-cracked regions.