Pencil-Drawn Electrode within Additively Manufactured Devices for Uric Acid Detection

Disposable electrochemical sensors have attracted increasing attention as low-cost, portable, and environmentally friendly alternatives to conventional analytical methods. Pencil-drawn electrodes (PDEs) offer a simple and sustainable approach, allowing rapid fabrication without conductive inks, sophisticated equipment, or laborious procedures. Here, a PDE was prepared on a stereolithography-additive manufactured substrate assembled on a fused-filament fabrication (FFF) additively manufactured electrochemical cell applied for uric acid (UA) sensing. The electrode was characterized by SEM and Raman spectroscopy, confirming its surface morphology, conductivity, and electrochemical activity. The sensor can be produced at a very low cost using nontoxic and readily available materials, making it suitable for point-of-care applications. The sensor demonstrated good reproducibility, stability, and selectivity, and exhibited electrochemical performance comparable to glassy-carbon electrodes (GCE) and carbon screen-printed electrodes (C-SPE) without any surface pretreatment. The analytical performance of the PDE was evaluated for UA, showing a linear response in the concentration range of 5.0-40.0 μmol L^-1, with a detection limit (LOD) of 0.2 μmol L^-1. Finally, it was successfully applied to the determination of UA in synthetic samples. Overall, this study presents a low-cost, eco-friendly, and reliable platform, highlighting the potential of PDEs on additively manufactured platforms for sustainable and accessible analytical chemistry.