Electrohydrodynamic (EHD) printing has been recently investigated as an effective technique to produce high-resolution conductive features. Most of the existing EHD printing studies for conductive features were based on metallic nanoparticle inks in a microdripping mode, which exhibited relatively low efficiency and commonly required high-temperature annealing process to achieve high conductivity. The EHD printing of high-resolution conductive features at a relatively low temperature and in a continuous cone-jetting mode is still challenging because the conductive inks might connect the charged nozzle, and the grounded conductive or semiconductive substrates to cause discharge and terminate the printing process. In this study, the EHD printing process of conductive polymers in a low-temperature cone-jetting mode was explored to fabricate conductive microstructures. The smallest width of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) lines was 27.25 ± 3.76 μm with a nozzle diameter of 100 μm. It was interesting to find that the electrohydrodynamically printed PEDOT:PSS-PEO features exhibited unique thermal properties when a dc voltage was applied. The conductive and thermal properties of the resultant features were highly dependent on the printing layer number. Microscale PEDOT:PSS features were further encapsulated into electrospun nanofibrous mesh to form a flexible sandwich structure. The EHD printing of PEDOT:PSS features with tunable conductive and thermal properties might be useful for the applications of flexible and wearable microdevices.
Keywords: PEDOT:PSS; electrohydrodynamic printing; flexible electronics; microscale conductive features; tunable conductive/thermal properties.