Conducting Polymer Jets in Electrostatically-Assisted Direct Ink Writing (eDIW)

The conducting polymer PEDOT:PSS has been in focus for its properties, suitable for the Direct Ink Writing (DIW) technique, such as high chemical stability and electrical conductivity. However, the process faces issues with jet stability. Modifying the solution with polyethylene oxide (PEO) can enhance the printability, along with an additional electric field (eDIW) feature. This work studies the PEDOT:PSS PEO mixture for eDIW, analyzing the jet flow subjected to the electric field (EF). The experimental results are compared to a novel theory also developed in this work to predict the electric field strength, the electric force and the resulting jet deflection. In the experiments a Phantom camera was used to record the jet at different EF strengths (0 to 10 kV), and the recorded jet configurations were compared to the theoretical predictions. The electrically-driven deflection for the 300 μm diameter jets became visible at 5 kV and intensified significantly at 9 kV. To measure the electric charge carried by the jet, a separate experiment was conducted: the jet was extruded onto a grounded plate and the electric current values were measured.