Green 3D-printed electrochemical sensors: From construction to use

The use of 3D printing for making electrochemical sensors has grown exponentially; however, most of these sensors are designed for single use. This contributes to significant plastic and chemical waste, which can be toxic and harmful to the environment. Although some strategies have been developed to produce electrodes in a more sustainable and eco-friendly manner, they often fail to address all stages of the construction and use of 3D-printed electrodes. In this study, we investigated each phase of the construction and use of 3D-printed electrodes to establish a comprehensive green approach. Electrodes were evaluated using cyclic voltammetry with an outer-sphere redox probe. Those printed with 0 % infill exhibited higher anodic currents compared to electrodes with 100 % infill, thereby reducing the amount of thermoplastic required. Direct heat embedding of silver wire into the electrode eliminated the need for silver epoxy, offering a more environmentally friendly method of electrical connection. Seawater was employed as a green solvent for electrochemical activation and produced equivalent results to sodium hydroxide. Finally, we demonstrated a closed-loop recycling and reuse strategy for 3D-printed electrodes during measurements. The proposed approach achieved a higher Eco-scale score than the conventional method of constructing 3D-printed electrodes. Overall, this study provides essential guidance for developing and utilizing 3D-printed electrochemical sensors in a fully sustainable and environmentally responsible manner.