Disposable 3D-printed electrochemical sensor as a potential tool for on-site analysis of metal-based paint materials in cultural heritage studies

A miniaturized and disposable 3D-printed electrochemical sensor was developed for the qualitative analysis of metal-containing paint test specimens relevant to cultural heritage studies. The device was fabricated using a conductive carbon black-poly(lactic acid) (CB-PLA) filament printed onto an acrylonitrile-butadiene-styrene (ABS) substrate. After printing, the sensor surface was electrochemically activated in 1.0 mol L−1 NaOH by applying a constant potential of +1.2 V for 30 min. Model paint test specimens composed of copper-based pigments (azurite, malachite, and verdigris), dispersed in four different binders (linseed oil, alkyd resin, acrylic resin, and rabbit glue), were subjected to an accelerated aging protocol corresponding to 161 years at 25 °C. The specimens were subsequently analyzed by voltammetry of immobilized microparticles (VIMP), in which a small amount of the pigment-binder material was mechanically transferred to the electrode surface. The electrochemical response was markedly influenced by the nature of the binder, revealing distinct behaviors among the pigment-binder systems and underscoring the role of the organic matrix in modulating copper electroactivity. Despite these matrix effects, copper was successfully detected in all paint test specimens investigated. Owing to its high sensitivity, miniaturized and disposable configuration, low-cost fabrication, and compatibility with scalable 3D printing, the proposed sensor platform shows strong potential for on-site electrochemical analysis of paint materials in cultural heritage artefacts. A CB-PLA electrochemical sensor was 3D-printed by fused filament fabrication. Aged paint test specimens were prepared using an accelerated aging protocol. Cu(II) was analyzed in aged paint test specimens by VIMP using the 3D CB-PLA sensor. The 3D CB-PLA sensor shows strong potential for low-cost on-site archaeometric analyses.