Optimizing Electrochemical Microprinting of Conducting Polymers: Scanning Electrochemical Cell Microscopy (SECCM)...

Scanning electrochemical cell microscopy (SECCM) is a versatile tool for localized electrochemical mapping, material modification, and microfabrication. In its hopping mode, the pipette-based system confines reactions to the meniscus contact area, allowing precise deposition control. Here, an SECCM-driven strategy for polypyrrole (PPy) microfabrication using phosphate buffer as the electrolyte, combined with an intermediate cleaning step to remove side products and prevent pipette clogging, is reported. This approach enables the production of uniform, circular PPy deposits with high reproducibility on gold substrates. A multi-microscopy "conveyor-belt" analysis - combining SEM, AFM, EDX, and Raman spectroscopy - reveals that phosphate ions intercalate into the PPy matrix during polymerization, as also seen in bulk studies. This intercalation is found to be reversible via post-deposition rinsing. Furthermore, this work demonstrates that cyclic voltammetry-based deposition enables patterned PPy growth on complex surfaces such as boron-doped carbon nanowalls, overcoming surface charge and wetting challenges. These findings expand the applicability of SECCM for 2D conducting polymer micro-/nanofabrication on both flat and structurally complex substrates.