Blue-Laser Ablation Treatment of Fully Integrated 3D-Printed Flexible Electrochemical Sensing Device

3D printing, particularly fused deposition modeling, is an important technology applied in the electrochemical field and typically requires surface activation procedures to remove excess of polymeric material and expose the conductive material. The laser ablation method presents advantages, such as low cost, speed, and elimination of chemicals. In this context, this study aims to investigate the modification of graphene/polylactic acid electrode (Gp/PLA) using blue-laser treatment for the improved detection of paracetamol (PAR). 2D Gp/PLA printed layers were deposited on an insulating polycaprolactone substrate to generate a compact three-electrode system in a planar configuration for microliter-drop analysis. The blue-laser-treated electrodes (BL) were obtained using optimized conditions of laser power and speed of 280 mW and 30 mm s−1, respectively. The Gp/PLA-BL electrode was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The SEM images showed the removal of PLA, which was also confirmed by FTIR and XPS spectra. Before the treatment, cyclic voltammograms at 50 mV s−1 of inner-sphere [Fe(CN)6]3−/4− redox pair exhibited an ill-defined voltammetric profile (ΔEp = 502 ± 4 mV) while an increase in the reversibility was achieved (ΔEp = 120 ± 1 mV) after the blue-laser ablation. Additionally, the lower charge transfer resistance was measured by electrochemical impedance spectroscopy after the treatment. As a proof-of-concept, analytical curves were constructed for PAR detection in a single drop using both non-treated and treated printed electrodes. An increase in the sensitivity of 2.4-fold was observed after the treatment.