3D printing pen using conductive filaments to fabricate affordable electrochemical sensors for trace metal monitoring

We report a 3D-pen fabricated electrochemical sensor using biodegradable carbon black/polylactic acid (PLA) filament for on-site monitoring of lead and copper in aqueous and hydroethanolic media. The sensors consist of 3D-printed PLA concentric tubes filled with conductive carbon-black/PLA in a similar design to a disc working electrode. Under optimized square-wave anodic-stripping-voltammetry (SWASV) parameters, the proposed sensor presented wide linear ranges (R2 > 0.99) in aqueous (up to 870 μg L−1 for both metals) and hydroethanolic media (up to 200 μg L−1 for lead and up to 400 μg L−1 for copper). The limits of detection were estimated as 1 and 2 μg L−1 for lead and copper in both media (100 s deposition time), respectively, below the strict limits established by regulatory agencies for water and fuel ethanol, with high precision (inter-day and inter-electrode RSD lower than 2.8%). The presence of Fe3+, Cd2+, Zn2+ and Hg2+ did not interfere in the detection of both metals. Recovery values for the analysis of fortified samples (tap-water and ethanol) ranged from 83% to 107%. Importantly, the concomitant presence of copper improved the sensitivity to lead in aqueous medium probably by the formation of a copper film, which did not occur in hydroethanolic medium. •3D-pen fabricated low-cost electrochemical sensors for on-site determinations.•Carbon black/polylactic acid filament as a biodegradable material for electrode fabrication.•Simultaneous voltammetric determination for Pb(II) and Cu(II) free from sample interference.•Analyses of spiked tap water and fuel ethanol samples with good recovery values and LODs.•Evidence of copper film formation leading to improved lead detection in aqueous medium.