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3D printing has changed many industries and research areas, and it is poised to do the same for electrochemistry and electroanalytical sciences. The ability to easily shape electrically conductive parts in complex geometries, something very difficult to do using traditional manufacturing techniques, can now be easily accomplished at home, opening the possibility of fabricating electrodes and electrochemical cells with geometries that were once unimaginable. This ability can be a milestone in electrochemistry, allowing the fabrication of systems tailored to specific applications. Unfortunately, this is not what is seen to date, with 3D printing mostly reproducing “traditional” designs, using little of the “freedom of design” promised by the technology. We reason that these results come from too much focus on reproducing the electrochemical behavior of metallic electrodes instead of understanding how material properties impact the performance of 3D printed electrodes and working within these constraints. 3D printing will change electrochemistry and electroanalytical sciences if we understand and learn to work with its limitations.

The concentration of environmental pollutants needs to be monitored constantly by reliable analytical methods since they pose a public health risk. Developing simple and affordable sensors for such pollutants can allow for large-scale monitoring economically. Here, we develop a simple electrochemical sensor for sulfanilamide (SFD) quantification using a phenolic resin substrate and a CO2laser to pyrolyze the sensor geometry over the substrate. The sensors are modified with carbon nanotubes via a simple drop-casting procedure. The carbon nanotube loading effect the electrochemical performance toward a redox probe and analytical performance for SFD detection is investigated, showing no net benefit beyond 1 mg L–1of carbon nanotubes. The effects of the modification on the SFD oxidation are shown to be more than just an electrode area effect and possibly attributed to the fast electron transfer kinetics of the carbon nanotubes. SFD detection is performed at small solution volumes under static (800 μL) and hydrodynamic conditions (3 mL) in a fully integrated, miniaturized batch-injection analyses cell. Both methods have a similar linear range from 10.0 to 115.0 μmol L–1and high selectivity for SFD determination. Both systems are used to quantify SFD in real samples as a proof of concept, showcasing the proposed device’s applicability as a sensor for environmental and public health monitoring of SFD.

A simple fabrication method to make electrochemical sensors is reported. The electrodes were fabricated with a commercial filament based on polylactic acid and carbon black (PLA/CB). They were engineered with a three-dimensional (3D) printing pen and poly(methyl methacrylate) template. The optimization parameters included the thickness and diameters of the electrodes. The electrode diameter was restricted by the 3D printing pen’s nozzle dimension, and larger diameters generated small cracks on the electrode surface, compromising their analytical signal. The electrode thickness can increase the electrical resistance, affecting their electrochemical response. The fabrication showed reproducibility (RSD = 4%). The electrode surface was easily renewed by sanding the electrodes, making them reusable. Additionally, the proposed sensor provided comparable electrochemical responses over traditional glassy carbon electrodes. Moreover, no (electro)chemical surface treatment was required for sensing applications due to the compromise between the thickness and diameters of the electrodes, effectively translating the filaments’ electrical properties to resulting materials. The electrodes’ analytical performance was shown for organic and inorganic species, including paraquat, Pb2+, and caffeic acid. As proof of concept, the analytical applicability was demonstrated for total polyphenolic quantification in tea samples. Therefore, this work provides an alternative to fabricating miniaturized electrodes, bringing valuable insights into PLA/CB 3D-printed sensors and opening possibilities for designing electrode arrays. Moreover, the proposed electrodes are promising platforms for paper-based microfluidic systems.