Tailorable conductivity of 3D PEDOT-based conductive nanostructures with pH-responsivity via a direct femtosecond laser writing technique

Although conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) are pivotal for flexible organic electronics, achieving tunable conductivity in high-resolution micro/nanoarchitectures remains a significant challenge. Conventional methods like inkjet writing and laser ablation not only offer limited resolution but also fail to provide the dynamic conductivity control required for advanced applications. To address these challenges, we developed a two-step nanofabrication strategy to produce PEDOT-based nanoarchitectures with tunable conductivities. A femtosecond direct laser writing technique was utilized to firstly create 3,4-ethylenedioxythiophene (EDOT)-based pH responsive nanostructures, and subsequently chemical oxidation was employed to convert EDOT-based nanostructures into conductive PEDOT-based ones, which enabled high-resolution conductive nanostructures with feature sizes as small as 250 nm and conductivity of 679 S m^-1. Additionally, the structures exhibited tunable conductivity ranging from 454 S m^-1 (pH = 13) to 1041 S m^-1 (pH = 1), due to the swelling/contraction of the pH responsive acrylate-functionalized derivative matrix. This work demonstrates a scalable strategy for creating high-resolution, pH-stimuli-responsive conductive polymer-based nanostructures such as PEDOT nanostructures, offering significant potential for advanced applications in nanoelectronics and biosensors.