Materiais, interfaces e arquiteturas analíticas em sensores eletroquímicos produzidos por manufatura aditiva

Abstract

Fused deposition modeling (FDM) additive manufacturing enables electrochemical sensors with different materials and architectures, although their performance depends on conductive-phase accessibility and electrode/solution interfacial properties. This thesis investigated surface modification, multi-material fabrication, analytical integration, and conductive filament development. First, commercial graphene/polylactic acid (G-PLA) electrodes were treated with N,N-dimethylformamide (DMF) and applied to epinephrine determination, achieving a linear range of 4–100 µmol L-1, a detection limit (LOD) of 0.2 µmol L-1, and recoveries of 96.9–102% in fortified human serum. Next, multi-feed/multi-nozzle printing it allowed for the integration of insulating PLA filaments and carbon black-conductive PLA filaments into a PLA matrix (CB-PLA) without material purging. Following DMF treatment, charge-transfer resistance decreased from 988 to 39.3 Ω. For fenitrothion determination in fortified honey, the sensor exhibited a linear range of 4–200 µmol L-1, an LOD of 1.3 µmol L-1, and recoveries close to 100%. Subsequently, a hyphenated platform combined static electrochemical, microfluidic electrochemical, and paper-based colorimetric detection, enabling three complementary catechol measurements from a single sample aliquot. All modalities showed a linear range of 50–600 µmol L-1, with LODs of 0.2, 1.4, and 16.1 µmol L-1, respectively. Finally, a polypropylene/CB filament containing incorporated Cu (PP/CB-Cu) during thermomechanical mixing was developed for oxalate sensing. Cu incorporation increased the analytical response approximately 3.5-fold compared with PP/CB, yielding a linear range of 10–1000 µmol L-1, an LOD of 2.48 µmol L-1, and recoveries of 95.4–107% in synthetic urine. Together, these findings demonstrate that controlling the interface, fabrication process, analytical architecture, and feedstock composition expands the functionality of additively manufactured electrochemical sensors.