A Sustainable 3D-Printed Electrochemiluminescence Microcell With an Integrated Three-Electrode System for Gallic Acid Determination.

This work presents a sustainable, fully 3D-printed electrochemiluminescence (ECL) microcell with an integrated three-electrode system for the sensitive determination of gallic acid. The device comprises a biodegradable polylactic acid (PLA) microcell integrated with a three-electrode system fabricated from carbon black-loaded PLA, enabling compact and low-cost electrochemical measurements. A luminol-based ECL system in carbonate buffer was employed, with carbon dots (CDs) introduced to enhance emission intensity by promoting electron transfer and reactive oxygen species generation, thereby amplifying the chemiexcitation pathway. The working electrode was modified with Prussian blue to improve electrochemical performance, while a pseudo-Ag/AgCl reference electrode ensured stable potential control. Under optimized conditions, the platform exhibited a linear response over 5-1000 μg L-1 with a limit of detection of 0.26 μg L-1 and good repeatability. Furthermore, smartphone-based RGB analysis provided a portable alternative for signal readout, achieving a detection limit of 3.70 μg L-1. The method was successfully applied to commercial cosmetic samples, showing good agreement with high-performance liquid chromatography. These results highlight the potential of the biodegradable 3D-printed ECL microcell as a simple, sustainable, and accessible platform for portable analytical applications.