Anodization treatment of flexible graphite sheet electrodes for Nernstian pH sensing.

The ability to accurately determine pH in various complex matrix samples is important for understanding and managing various chemical environments. While glass pH probes are the standard for pH measurements, they present several drawbacks, including the need of frequent calibrations, and high susceptibility to interference from alkali metals. Herein, we demonstrate a voltammetric Nernstian pH sensing approach utilizing low-cost, flexible graphite sheet (GS) electrodes.

Additively Manufactured Electrodes for Simultaneous Detection of 2,4,6-Trinitrotoluene and Cyclotrimethylenetrinitramine in Postexplosive Residues and Environmental Samples.

This work reports the use of a custom-made filament based on polylactic acid and graphite to construct additively manufactured working electrodes, using fused filament fabrication 3D-printing technology, to simultaneously detect the explosives 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX). We propose a simple strategy to increase detectability that consists of an electrochemical preconcentration step (-1.3 V Ag|AgCl|KCl for 30 s) to reduce RDX and TNT species on the 3D-printed electrode prior a single differential pulse stripping voltammetry scan in Britton-Robinson buffer (pH = 6.

Enhancing fouling resistance of graphite sheets for electrochemical sensing of bisphenol-A.

Bisphenol A (BPA) is widely used in the production of polycarbonate plastics and epoxy resins, and it is now classified as an emerging pollutant due to its extensive environmental presence. Given the need for effective BPA monitoring, this study presents a cost-effective electrochemical approach for its quantification, using pyrolytic graphite sheets (GSs) as working electrodes integrated into a 3D-printed electrochemical cell. Despite initially exhibiting an intense voltammetric peak for BPA, fouling of the GS surface resulted in a progressive decrease in the BPA signal over successive scans.

Sustainable 3D-printing from coconut waste: conductive PLA-biochar filaments for environmental electrochemical sensing.

The integration of eco-friendly composites based on polymers and conductive fillers offers exciting opportunities for creating sustainable materials with superior electrical properties, paving the way for innovative advancements in electroanalytical devices. In this study, we explored the potential of biodegradable polylactic acid (PLA), carbon black (CB), and biochar derived from coconut shell waste to develop fused filament fabrication (FFF) filaments without the need for hazardous solvents. To assess the influence of biochar on the electrochemical properties, additional filaments composed exclusively of CB and PLA were also fabricated for comparison.

Low-cost and portable 3D-printed sensor for the determination of secnidazole in pharmaceutical and seized drug samples.

Additive manufacturing (3D printing), particularly fused deposition modeling (FDM), has rapidly advanced, offering customized designs, reduced waste, lower costs, and fast prototyping for electroanalytical applications. Herein, the electrochemical secnidazole (SCZ) behavior was studied using additive manufactured electrodes (AMEs) based on commercial carbon black and polylactic acid (PLA) conductive filament. Before use, AMEs were submitted to electrochemical/chemical activation (+1.

Additively manufactured ready-to-use platform using conductive recycled PLA for ketamine sensing.

The use of 3D-printed electrodes is reported fabricated from in-house conductive filament composed of a mixture of recycled poly (lactic acid) (rPLA), graphite (Gpt), and carbon black (CB) for fast detection of the abused drug ketamine. Firstly, the performance of these electrodes was evaluated in comparison to 3D-printed electrodes produced employing a commercially available conductive filament. After a simple pretreatment step (mechanical polishing), the new 3D-printed electrodes presented better performance than the electrodes produced from commercial filament in relation to peak-to-peak separation of the redox probe [Fe(CN)]/ (130 mV and 759 mV, respectively), charge transfer resistance (R = 1.

Bio-based plasticizer Babassu oil for custom-made conductive additive-manufacturing filaments: towards 3D-printed electrodes applied to cocaine detection.

Babassu (Atallea sp.), a native palm tree from South America's Amazon produces bio-oil and biochar with significant potential for industrial applications. Babassu oil as a bio-based plasticizer is reported here for the first time to replace petrochemical alternatives in the production of conductive filaments for additive manufacturing purposes.

Tailoring 3D-printed sensor properties with reduced-graphene oxide: improved conductive filaments.

The development of a tailored filament is reported composed of reduced graphene oxide (rGO) and carbon black (CB) in a polylactic acid (PLA) matrix and its use in the production of electrochemical sensors. The electrodes containing rGO showed superior performance when compared with  those prepared in the absence of this material. Physicochemical and electrochemical characterizations of the electrodes showed the successful incorporation of both rGO and CB and an improved conductivity in the presence of rGO (lower resistance to charge transfer).

Portable Atmospheric Air Plasma Jet Pen for the Surface Treatment of Three-Dimensionally (3D)-Printed Electrodes.

Three-dimensional (3D) printing is an emerging technology to develop devices on a large scale with potential application for electroanalysis. However, 3D-printed electrodes, in their native form, provide poor electrochemical response due to the presence of a high percentage of thermoplastic polymer in the conductive filaments. Therefore, surface treatments are usually required to remove the nonconductive material from the 3D-printed electrode surfaces, providing a dramatic improvement in the electroanalytical performance.

Rapid sequential determination of the explosives 2,4,6-trinitrotoluene and cyclotrimethylenetrinitramine in forensic samples employing a graphite sheet sensor and cyclic square-wave stripping voltammetry.

The development of a portable analytical procedure is described for rapid sequential detection and quantification of the explosives 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX) in forensic samples using a graphite sheet (GS). A single GS platform works as a collector of explosive residues and detector after its assembly into a 3D-printed cell. The detection strategy is based on cyclic square-wave stripping voltammetry.

An innovative approach for selective and robust screening of NBOHs, NBOMes, and LSD in forensic samples using a 3D-Printed electrochemical double cell.

Lysergic acid diethylamide (LSD) and two phenethylamine classes (NBOHs and NBOMes) are the main illicit drugs found in seized blotter papers. The preliminary identification of these substances is of great interest for forensic analysis. In this context, this work constitutes the inaugural demonstration of an efficient methodology for the selective detection of LSD, NBOHs, and NBOMes, utilizing a fully 3D-printed electrochemical double cell (3D-EDC).

Novel disposable and portable 3D-printed electrochemical apparatus for fast and selective screening of 25E-NBOH in forensic samples.

The advent of new psychoactive substances (NPS) has caused enormous difficulty for legal control since they are rapidly commercialized, and their chemical structures are routinely altered. In this aspect, derivatives phenethylamines, such as 25E-NBOH, have received great attention in the forensic scenario. Hence, we propose portable and cost-effective (U$ 5.

CO-plasma surface treatment of graphite sheet electrodes for detection of chloramphenicol, ciprofloxacin and sulphanilamide.

Graphite sheet (GS) electrodes are flexible and versatile substrates for sensing electrochemical; however, their use has been limited to incorporate (bio)chemical modifiers. Herein, we demonstrated that a cold (low temperature) CO plasma treatment of GS electrodes provides a substantial improvement of the electrochemical activity of these electrodes due to the increased structural defects on the GS surface as revealed by Raman spectroscopy (I/I ratio), and scanning electron microscopy images. XPS analyses confirmed the formation of oxygenated functional groups at the GS surface after the plasma treatment that are intrinsically related to the substantial increase in the electron transfer coefficient (K values increased from 1.

A novel 3D-printed graphite/polylactic acid sensor for the electrochemical determination of 2,4,6-trinitrotoluene residues in environmental waters.

Here, lab-made graphite and polylactic acid (Gpt-PLA) biocomposite materials were used to additively manufacture electrodes via the fused deposition modeling (FDM) technique for subsequent determination of the explosive 2,4,6-trinitrotoluene (TNT, considered a persistent organic pollutant). The surface of the 3D-printed material was characterized by SEM and Raman, which revealed high roughness and the presence of defects in the graphite structure, which enhanced the electrochemical response of TNT. The 3D-printed Gpt-PLA electrode coupled to square wave voltammetry (SWV) showed suitable performance for fastly determining the explosive residues (around 7 s).

Determination of scopolamine and butylscopolamine in beverages, urine and Buscopan® tablets samples using electrophoresis microchip with integrated contactless conductivity detection.

The number of cases in which scopolamine (SCO) was used for both recreational and predatory purposes has increased dramatically in recent decades. Linked to this, there is a concern about obtaining SCO through thermal degradation of butylscopolamine (BSCO) - an active ingredient of Buscopan® - a drug sold without a medical prescription. In this study, mixtures containing SCO and BSCO were separated and detected on a microchip electrophoresis (ME) device with integrated capacitively coupled contactless conductivity detection (CD) using a running buffer composed of 40 mmol L of butyric acid and 25 mmol L of sodium hydroxide (pH 5.

3D-printed electrochemical cells with laser engraving: developing portable electroanalytical devices for forensic applications.

A new electrochemical device fabricated by the combination of 3D printing manufacturing and laser-generated graphene sensors is presented. Cell and electrodes were 3D printed by the fused deposition modeling (FDM) technique employing acrylonitrile butadiene styrene filament (insulating material that composes the cell) and conductive filament (lab-made filament based on graphite dispersed into polylactic acid matrix) to obtain reference and auxiliary electrodes. Infrared-laser engraved graphene, also reported as laser-induced graphene (LIG), was produced by laser conversion of a polyimide substrate, which was assembled in the 3D-printed electrochemical cell that enables the analysis of low volumes (50-2000 μL).

Nickel Oxy-Hydroxy/Multi-Wall Carbon Nanotubes Film Coupled with a 3D-Printed Device as a Nonenzymatic Glucose Sensor.

A rapid and simple method for the amperometric determination of glucose using a nanocomposite film of nickel oxyhydroxide and multi-walled carbon nanotube (MWCNTs) was evaluated. The NiHCF)/MWCNT electrode film was fabricated using the liquid-liquid interface method, and it was used as a precursor for the electrochemical synthesis of nickel oxy-hydroxy (Ni(OH)/NiOOH/MWCNT). The interaction between nickel oxy-hydroxy and the MWCNTs provided a film that is stable over the electrode surface, with high surface area and excellent conductivity.

A simple, fast, portable and selective system using carbon nanotubes films and a 3D-printed device for monitoring hydroxychloroquine in environmental samples.

In this work, an electrochemical method was developed for rapid and sensitive detection of hydroxychloroquine (HCQ), an ineffective candidate drug for COVID-19 treatment however widely consumed during the pandemic, in aqueous samples using a multi-walled carbon nanotubes (MWCNT) film produced through the interfacial method on the indium tin oxide electrode (ITO). According to Raman spectroscopy, X-ray diffraction, UV-vis spectroscopy, Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and atomic force microscopy, the interfacial method produces homogeneous thin films of carbon nanotubes on the substrate surface, which keep connected to the surface forming a three-dimensional microporous structure. The electrochemical behavior and oxidation kinetics of HCQ were also investigated in the MWCNT film.

Electrochemical platform produced by 3D printing for analysis of small volumes using different electrode materials.

Fused deposition modeling (FDM) 3D printing is a promising additive manufacturing technique to produce low-cost disposable electrochemical devices. However, the print of devices like well-known screen-printed electrodes (all electrodes on the same device) is difficult using the available technology (few materials available for production of working electrodes). In this paper we present a procedure to produce disposable and robust electrochemical devices by FDM 3D printing that allows reproducible analysis of small volumes (50-2000 μL).

Lab-made 3D-printed electrochemical sensors for tetracycline determination.

Antibiotics such as tetracycline (TC) are widely prescribed to treat humans or dairy animals. Therefore, it is important to establish affordable devices in laboratories with minimal infrastructure. 3D printing has proven to be a powerful and cost-effective tool that revolutionizes many applications in electrochemical sensing.

Carbon Black Integrated Polylactic Acid Electrodes Obtained by Fused Deposition Modeling: A Powerful Tool for Sensing of Sulfanilamide Residues in Honey Samples.

Sulfanilamide (SFL) is used to prevent infections in honeybees. However, many regulatory agencies prohibit or establish maximum levels of SFL residues in honey samples. Hence, we developed a low-cost and portable electrochemical method for SFL detection using a disposable device produced through 3D printing technology.

Development of New Simple Compositions of Silver Inks for the Preparation of Pseudo-Reference Electrodes.

Silver materials are known to present excellent properties, such as high electrical and thermal conductivity as well as chemical stability. Silver-based inks have drawn a lot of attention for being compatible with various substrates, which can be used in the production uniform and stable pseudo-reference electrodes with low curing temperatures. Furthermore, the interest in the use of disposable electrodes has been increasing due to the low cost and the possibility of their use in point-of-care and point-of-need situations.

Additively manufactured electrodes for the electrochemical detection of hydroxychloroquine.

Although studies have demonstrated the inactivity of hydroxychloroquine (HCQ) towards SARS-CoV-2, this compound was one of the most prescribed by medical organizations for the treatment of hospitalized patients during the coronavirus pandemic. As a result of it, HCQ has been considered as a potential emerging contaminant in aquatic environments. In this context, we propose a complete electrochemical device comprising cell and working electrode fabricated by the additive manufacture (3D-printing) technology for HCQ monitoring.