Spectroelectrochemical sensing of reaction intermediates and products in an affordable fully 3D printed device.

Recent advances in fused deposition modelling 3D printing (FDM 3DP) and synthesis of printable electrically conductive materials enabled the manufacture of customized electrodes and electrochemical devices by this technique. The past couple of years have seen a boom in applying approaches of FDM 3DP in the realm of spectroelectrochemistry (SEC). Despite significant progress, reported designs of SEC devices still rely on conventionally manufactured optical components such as quartz windows and cuvettes. To bridge this technological gap, in this work we apply bi-material FDM 3DP combining electrically conductive and optically translucent filaments to manufacture working electrodes and cells, constituting a fully integrated microfluidic platform for transmission absorption UV-Vis SEC measurements. The cell design enables de-aeration of samples and their convenient handling and analysis. Employing cyclic voltammetric measurements with ruthenium(III) acetylacetonate, ethylviologen dibromide and ferrocenemethanol redox-active probes as model analytes, we demonstrate that the presented platform allows SEC sensing of reactants, intermediates and products of charge transfer reactions, including the inspection of their long-term stability. Approaches developed and presented in this work pave the way for manufacturing customized SEC devices with dramatically reduced costs compared to currently available commercial platforms.