Printing parameters affect the electrochemical performance of 3D-printed carbon electrodes obtained by fused deposition modeling

Thermoplastic filaments containing conductive carbon materials have contributed tremendously to innovations in the scientific scenario, however, the high charge transfer resistance of available materials sets a challenge for the development of 3D-printed electrochemical sensors. To solve this problem, several research groups have proposed chemical and physical post-treatments that are time-consuming and affect the structural integrity of materials. Herein, we systematically investigated the influence of printing parameters (orientation, layer thickness, number of perimeters and printing perimeter speed) on the electrochemical performance of sensors. For these studies, 3D-printed electrodes (rectangular shape) were printed using an affordable filament of car-bon black integrated in polylactic acid (CB/PLA), and measurements by cyclic voltammetry (CV), and electro-chemical impedance spectroscopy (EIS) using 10 mmol/L [Ru(NH3)6]2 +/-/3 +/- as redox probe were performed. The results showed that electrodes printed under vertical orientation, with lower layer thickness (0.05 mm) and print perimeter speed (30 mm s-1) using two perimeter numbers provided the best electrochemical per-formance (faradaic peak current intensity and lower peak-to-peak separation). To understand the improvement of electrochemical responses, experiments by Raman spectroscopy and multivariate curve resolution by alter-nating least squares (MCR-ALS) were carried out which showed greater availability and distribution of con-ducting sites under the selected conditions. Thus, it can be inferred that 3D-printing parameters are important features to allow the manufacture of improved carbon electrochemical platforms.