3D-printing of electrodes from commercial filaments : towards a better understanding of composition/electrochemical properties relationship for enhanced electroanalysis

3D printing is a very attractive technology that has gained a huge interest in many fields, including electroanalysis, over the last decade. Among the variety of 3D printing techniques, Fused Deposition Modelling (FDM) allows 3D parts to be easily printed, at a low cost, through the layer-by-layer deposition of a molten filament. It has been recently demonstrated that commercial or home-made conductive filaments may be used to produce electrochemical sensors, relevant in sensing and biosensing of various molecules of environmental, food, or clinical interest1,2. The conductive filaments are composed of composite materials, based on an easy-to-print supporting polymer, typically polylactic acid (PLA), filled with carbon nanomaterials, such as carbon black, carbon nanotubes or graphene. PLA offers the advantage of being a low-cost biosourced and biodegradable material, but it is not conductive. To improve the electrochemical performances of as-printed electrodes, mechanical, physical, chemical, electrochemical and biological pre-treatments have been proposed3. The treatment aims at both eliminating the surface PLA layer and activating the exposed carbon fillers. Although many articles have been published on FDM-printed electrodes in recent years, most of them describe fabrication and treatment processes from commercial filaments, easily available for all laboratories, but with a badly known composition as a counterpart.In this work, two commercial conductive filaments have been compared for the production of disk electrodes. The first one (carbon black filament from Proto-Pasta) has been extensively characterized in the past using various techniques, it is a robust filament already harnessed to develop a wide range of biosensors. The second one (Alfaohm from FiloAlfa) has been very rarely used4, it is declared to contain carbon black (CB) and carbon nanotubes (CNT) but the respective concentrations remain unknown. Herein, we will present the comprehensive characterization performed on both materials by electron microscopy, IR, Raman, contact angle measurement, before and after two types of treatments (electrochemical cycling in 1M NaOH, and oxygen plasma). Results will be correlated with electrochemical properties measured using cyclic voltammetry and electrochemical impedance spectroscopy for a better understanding of treatment processes and their effect on electrochemical transfer efficiencies at the electrode/electrolyte interface.References:1. M. H. Omar, K. A. Razak, M. N. A. Wahab, H. H. Hamzah, RSC Adv. 2021, 11, 16557.2. R.D. Crapnell, I.V.S. Arantes, J.R. Camargo, E. Bernalte, M.J. Whittingham, B. C. Janegitz, T.R.L.C. Paixao, C.E. Banks, Microchim. Acta 2024, 191, 96.3. D.P. Rocha, R.G. Rocha, S.V.F. Castro, M.A.G. Trindade, R.A.A. Munoz, E. M. Richter, L. Angnes, Electrochem. Sci. Adv., 2022, 2:e21001364. J. E. Contreras-Naranjo, V. H. Perez-Gonzalez, M. A. Mata-Gómez, O. Aguilar, Electrochem. Commun. 2021, 130, 107098.