We report the electrochemical potential of conductive filaments produced with recycled polylactic acid (rPLA) alongside a mixture of graphite (Gpt) and/or carbon black (CB) and castor oil to create an electrode ready-to-use. Additively-manufactured electrodes (AMEs) were compared with commercial-conductive filament composed of PLA and CB. The Gpt-CB-rPLA and CB-rPLA sensors showed lower charge-transfer resistance (Rct) and a greater heterogenous rate constant, k0, (Rct = 1040 +/- 50 Omega and 1810 +/- 30 Omega and k0 = 6.91 (+/- 0.58) x10-3 and 5.31 (+/- 0.40) x 10-3 cm s-1, respectively) compared to the sensor from the commercial filament (Rct = 9620 +/- 280 Omega and k0 = 3.62 (+/- 0.38) x10-3 cm s-1). The electrochemical response of [Fe(CN6)]3-/4- displayed a peak-to-peak separation of 180 +/- 8 mV (Gpt-CB-rPLA) and 240 +/- 6 mV (CB-rPLA) compared to commercial AME (740 +/- 10 mV), without any surface treatment. The filaments were used to create a 2,4,6-trinitrotoluene (TNT) detection platform with linear range of 5-20 and 5-100 mu mol L-1 for Gpt-CB-rPLA and CB-rPLA, respectively. The collector-detector device was applied for the analysis of a blast simulation. Finally, it is worth noting that the results obtained are without electrode treatment/activation, indicating that the rough surface of the additively manufactured electrode is an additional feature of the device for collecting explosive residues, simply by rubbing the additively manufactured platform on different surfaces in crime scenarios.

The development of high-performance, bespoke conductive filament is a challenge to overcome to increase the uptake of additive manufacturing electrochemistry. In this work we report the first conductive filament embedded with gold nanoparticles (AuNPs). This is achieved through the synthesis of AuNPs within castor oil (AuNP-CO), a recognised plasticiser used to fabricate bespoke conductive filaments. The presence of AuNPs in castor oil is first confirmed through UV-Vis and TEM measurements and after the AuNP-CO is utilised as a substitute for CO within a filament composition comprising of 25 wt% carbon black, 65 wt% recycled PLA and 10 wt% AuNP-CO. The inclusion of AuNP-CO provided both enhanced electrical properties, as well as low- temperature flexibility, without compromising on the thermal stability. This filament was shown to have excellent printability, with the presence of AuNPs confirmed on the surface of the additively manufactured electrodes. The electrodes containing AuNP-CO were benchmarked against only CO containing ones and a commercial alternative, whereby the AuNP-CO electrodes provided enhanced electrochemical performance toward both outer and inner sphere redox probes. Additionally, the AuNP-CO electrodes were shown to have significantly enhanced electroanalytical properties toward the detection of dopamine, showing double the sensitivity. We expect this first report of precious metal nanoparticle embedded conductive filament will broaden the scope of additive manufacturing in electrochemistry and significantly increase the potential for commercially viable products to emerge from this field.

Laser-induced graphene, which was first reported in 2014, involves the creation of graphene by using a laser to modify a polyimide surface. Since then, laser-induced graphene has been extensively studied for application in different scientific fields. One beneficial approach is the use of laser-induced graphene coupled with electrochemistry, where there is a growing need for disposable, conductive, reproducible, flexible, biocompatible, sustainable, and economical electrodes. In this mini overview, we explore the use of laser-induced graphene as the basis of electroanalytical sensors. We first introduce laser-induced graphene, before moving to the use of laser-induced graphene electrodes highlighting the various approaches and different laser parameters used to produce different graphene micro and macro structures, whilst describing how these structures are characterised and benchmarked for those working in the field of laser-induced graphene electrodes for comparison aspects. Next, we turn to the use of laser-induced graphene electrodes as the basis of electrochemical sensing platforms towards key analytes and its use in the development of biosensors. We provide a critical overview of the use of laser-induced graphene sensors compared to screen-printed and additive manufactured electrodes, providing future suggestions for the field.

Additive manufacturing electrochemistry allows for the production of bespoke sensing devices, that can be produced rapidly on-site. Through the production of specialised filament, researchers have been able to begin to compete with the electroanalytical performance of classical electrodes, however, only aqueous systems have ever been viable for exploration. In this work, we report the first production of a low material cost poly(propylene) (PP) based conductive filament and its application toward electroanalysis within an organic medium, acetonitrile. By leveraging the chemical stability of PP, alongside the conductive properties of carbon black (CB) and the low-cost nature of graphite (G), high-performance electrodes could be printed at a material cost of less than 0.01 pound each. The filament containing 20 wt% CB, 20 wt% G and 60 wt% PP was electrochemically characterised, producing a k0 of 2.08 (+/- 0.22) x 10-3 cm s-1. The additive manufactured electrodes were then applied to detect chlorpromazine in acetonitrile, producing a sensitivity of 51.8 nA mu M-1, limit of detection of 80 mu M and limit of quantification of 266 mu M. This work shows how, through the production of bespoke filaments, additive manufacturing electrochemistry can explore new areas of electrochemical research that are currently untapped.

In forensic investigations, the detection of Scopolamine, popularly known as Burundanga or Devil's Breath, is of significant interest due to its potential involvement in cases of attempted murder or suicide. Currently, no efficient screening methods exist for Scopolamine detection in such forensic contexts. This study presents a novel method combining screen-printed graphite electrodes (SPGE) with square-wave voltammetry (electrochemical step) and Dragendorff reagent (colorimetric step) to detect Scopolamine in drinks (gin, tonic water, whisky, and energy drinks) and biological samples (urine, saliva, and vitreous humor). The method provides two distinct analytical responses: a visible color change (from orange to yellow) via the colorimetric reaction, and the electrochemical behavior of Scopolamine in both anodic and cathodic scans, ensuring robust and accurate identification. For the first time, the electrochemical behavior of both redox processes of Scopolamine is investigated. The proposed method demonstrated a wide linear range (0.025-0.225 mg mL- 1 for the oxidation and 0.025-0.175 mg mL-1 for the reduction process) with a low limit of detection of 5.0 mu g mL- 1, making it suitable for forensic applications. Stability of the electrochemical response was studied with SPGE showing relative standard deviations (RSD) of less than 3 % for Ep and Ip across multiple electrodes (N = 3). Interference studies confirmed the method's high selectivity for Scopolamine detection. Additionally, Scopolamine was successfully identified in both beverage and biological samples with recoveries near 100 %, indicating the absence of matrix effects. The methodology using both electrochemical with a colorimetric approach presents a promising, rapid, and selective screening method for Scopolamine detection in forensic scenarios.

The development of a print-at-home, low-cost, and miniaturized paper-based cell with 3D-printed electrodes using a 3D-printing pen and a bespoke conductive filament for detecting capsaicin in hot sauce is reported herein. The material cost of producing each electrode was less than 0.01 pound. The new filament was electrochemically benchmarked against a commercial CB/PLA conductive filament. The CB/graphite/recycled PLA filament molded in paper platform produced a heterogeneous rate constant, k0obs, of 1.64 (+/- 0.13) x 10-3 cm s-1 and resistance of only 166 +/- 0.13 Omega compared to 0.43 (+/- 0.05) x 10-3 cm s-1 and 1613 +/- 220 Omega for an identical device printed from commercial CB/PLA filament. The newly developed device using the bespoke filament on kraft paper was applied successfully to detect capsaicin (CAP). CAP showed a characteristic peak at approximately +0.7 V for the bespoke CB/graphite/rPLA filament in cyclic voltammetry. A small peak at +1.0 V is observed when using the commercial filament. Additionally, a linear range of 5 to 20 mu M and a sensitivity of 0.0093 mu A mu M was obtained for CAP when applying differential pulse voltammetry using the paper-based device with the bespoke filament. Limits of detection and quantification were calculated at 1.21 and 3.98 mu M, respectively. The new system quantifies CAP in a commercial red pepper hot sauce (Tabasco). This work highlights how a low-cost kraft paper platform and a bespoke conductive filament can be combined to create an effective electrochemical device using simple tools for quantifying capsaicin in real samples. Additionally, it highlights the potential of these materials and techniques to develop home-based sensors.

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)6]3-/4- (130 mV and 759 mV, respectively), charge transfer resistance (Rct = 1.04 ± 0.05 kΩ and 9.62 ± 0.03 kΩ, respectively), and heterogeneous rate constant (k0 = 7.16 ± 0.05 × 10–3 cm s−1 and 3.57 ± 0.03 × 10–3 cm s-1, respectively). Excellent analytical characteristics for the detection of ketamine were achieved, including wide linear range (10 to 250 μmol L-1), excellent sensitivity (0.024 ± 0.001 μA μmol L-1), low limit of detection (LOD = 0.7 μmol L-1), and recovery values from 82 to 115

The electrochemical synthesis of nickel-cobalt (Ni-Co) layered double hydroxides (LDHs) on a nickel-coated graphite support for water splitting applications was investigated. Three different electrochemical approaches, namely, cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP), were employed for evaluating the electrodeposition of Ni-Co LDHs. The graphite support was initially coated with a thin layer of Ni by applying 50 mA cm-2 constant current density for 120 s. Raman spectroscopy results confirmed the intercalation of nitrates, evidenced by the characteristic Raman bands at 1033 cm-1 (nu 1) and 1329 cm-1 (nu 3). These characteristic bands were indicative of nitrate intercalation, a key feature of LDHs, further supporting the classification of the synthesized material as NiCo LDHs on a nickel-coated graphite support. It was observed that the electrochemical routes used for the synthesis influenced the morphology, composition, and electrochemical behavior of the obtained Ni-Co LDHs. Moreover, atomic force microscopy (AFM) measurements revealed distinct nanoscale surface characteristics associated with the synthesis methods, with the Ni-Co LDH synthesized via the CV route exhibiting higher surface heterogeneity than that synthesized via the constant potential method (CA), resulting in a more textured surface. These findings were further supported by roughness average (Ra) values, where CV-synthesized Ni-Co LDH displayed the highest Ra of 221 nm, indicating a more extensive active surface area. The electrochemical performance, both for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), were correlated with these surface variations. This study provides valuable insights into the electrochemical experimental parameters for the synthesis of Ni-Co LDHs and their potential application in water splitting processes.

Additive manufacturing electrochemistry has the potential to revolutionise the wearable sensors industry through the rapid and customisable production of sensors; however, the currently available conductive filaments are not fit for purpose due to issues with their base polymers and filler loadings. In this work, we present the development of a highly flexible and conductive filament for additive manufacturing made with 40 wt% carbon black (CB) in thermoplastic poly(urethane) (TPU). This optimised loading of CB achieved an ideal balance between flexibility, printability, conductivity, and electrochemical performance, as demonstrated by bulk resistance measurements, TGA, SEM, XPS, Raman and through electrochemical scan rate studies, where a heterogeneous electron transfer rate constant (k0) of 2.69 (+/- 0.10) x 10-3 cm s-1 was obtained. Importantly, the electrodes exhibited great stability over 100 scans and excellent reproducibility after cleaning and re-use. Moreover, the additively manufactured electrodes were tested with the connection stem bent at five different angles, showing no deterioration of their electrochemical performance. Furthermore, we show that within the use of additive manufacturing technology, the choice of printer is key to avoid print failure; using a distance from extruder gears to nozzle, namely the filament path, as short as possible results in more reproducible additive manufacturing. Finally, the electrodes bent to the highest angle were applied to the simultaneous multianalyte detection of dopamine, uric acid and nitrite within urine demonstrating an excellent electroanalytical performance with a clear separation of the three peaks. This highly flexible and conductive material holds the potential to elevate additive manufacturing within the fields of flexible electronics and wearable electrochemical sensors.

Accurate, rapid, and cost-effective validation of water quality is essential to ensure that the World Health Organization's (WHO) standards are met and that the United Nations Sustainable Development Goal 6-Clean Water and Sanitation is achieved. To this end, the development of additive-manufactured electrodes using recycled polylactic acid, nanocarbon black, and micro-sized bismuth oxide is reported. These electrodes, that are fabricated using a thermal mixing approach, can be customized to incorporate varying amounts of bismuth oxide (1, 2.5, and 5 wt%) maintaining the integrity of the base polymer. The electrodes developed in this work demonstrate significant potential for the electrochemical detection of lead (II) within water, achieving limits of detection of 0.79, 0.93, and 4.29 mu g L-1 (3 sigma), for the 1, 2.5, and 5 wt% bismuth oxide sensors, respectively. These detection limits are notably below the WHO recommended threshold of 10 mu g L(-1 )for lead in domestic water and even achieve the 2036 European Union targets of 5 mu g L-1. The 2.5 wt% bismuth oxide electrodes exhibit excellent reproducibility and specificity, achieving average recovery rates of 98.28% and 100.15% in the analysis of spiked lead (II) samples in deionized and condensed atmospheric water, respectively. This approach is further validated against inductively coupled plasma mass spectroscopy measurements.

The demand for low-cost, efficient, selective, and sensitive analytical methods is increasing globally, making electroanalysis combined with screen-printed electrodes an appealing option. Gold, known for its excellent electrical conductivity and biocompatibility, improves the electrocatalytic activity of the sensors and reduces interference with other substances. Here, we propose the modification of disposable sensors with edible gold leaf, which is a cost-effective alternative to sputtering. The gold leaf was immobilized on the screen-printed electrode surface with chitosan. L-tyrosine, an amino acid, and an important biomarker for the diagnosis of various diseases was detected as a proof-of-concept. Using square-wave voltammetry for the determination of L-tyrosine, the disposable sensor modified with gold leaf showed a linear response in the range between 0.10 to 70 μmol L−1 with a limit of detection of 0.09 μmol L−1. Overall, the use of gold leaf to modify disposable electrochemical sensors for L-tyrosine detection represents a promising approach for electrochemical sensing.

Abstract Screen‐printed electrochemical sensing platforms are ubiquitous within the field of electrochemistry where they provide benefits of being disposable, cost‐effective, reproducible, easily customisable, portable and allow one to transfer the laboratory approach into the field. In this review, we introduce the concept of screen‐printed electrodes, we summarise positive and negative aspects before moving into the current highlights of using traditional screen‐printed carbon electrodes within the field of electroanalysis. We then look to cover metallic and bulk modified varieties, geometric changes (micro, microband and associated arrays), electrode activation and finally the physical length of screen‐printed electrodes, providing insights for future research.

Norovirus (NoV) is the predominant cause of foodborne illness globally; current detection methods are typically expensive, have inadequate sensitivities, and utilize biological receptors with poor stability. Therefore, accurate, cost-effective, and highly stable detection methods are needed to screen for NoV in foods. We developed molecularly imprinted polymer nanoparticles (nanoMIPs) to detect NoV using a small target epitope (12 amino acids) with a solid-phase synthesis approach. The performance of three batches of nanoMIPs with varying monomer compositions (nanoMIP-1, -2, and -3) were compared both experimentally and computationally. Surface plasmon resonance examined nanoMIP binding affinity to norovirus virus-like particles (NoV-LPs), whereby nanoMIP-1 had the lowest KD value of 0.512 μM. This is significant, as traditional targets for generation of norovirus ligands previously reported were generated against drastically larger norovirus capsid segments that have limitations in ease of production. Further, an electrochemical sensor was developed by covalently attaching the nanoMIPs to glassy carbon electrodes. In agreement with our predictions from density functional theory simulations, electrochemical impedance spectroscopy showed a sensitive response toward NoV-LPs for nanoMIP batches tested; however, nanoMIP-1 was optimal, with an excellent detection limit of 3.4 pg/mL (1.9 × 105 particles/mL). Due to its exceptional performance, nanoMIP-1 was immobilized to screen-printed electrodes and utilized within a thermal sensor, where it exhibited a low detection limit of 6.5 pg/mL (3.7 × 105 particles/mL). Crucially, we demonstrated that nanoMIP-1 could detect NoV in real food samples (romaine lettuce) by using electrochemical and thermal sensors. Consequently, the study highlights the exceptional potential of nanoMIPs to replace traditional biological materials (e.g., antibodies) as sensitive, versatile, and highly stable receptors within NoV sensors.

Current reports of healthcare sensors within literature that use additive manufacturing electrochemistry all utilise conductive PLA, which is unsuitable for widespread use within the industry. Poly(ethylene terephthalate glycol (PETg) is a polymeric material with proven attributes for additive manufacturing due to its thermal and mechanical properties. Likewise, its excellent chemical stability transforms PETg into a desirable alternative for developing healthcare sensing devices. In this work, we report the production, physicochemical and electrochemical characterisations, as well as the electroanalytical performance of an enhanced electrically conductive additive manufacturing filament made with recycled poly(ethylene terephthalate glycol (rPETg) and a combination of carbon black, multi-walled carbon nanotubes and graphene nanoplatelets as conductive fillers. The post-print activation of additive manufactured electrodes from this material is optimised and shown to produce enhanced electrochemical performance compared to non-activated electrodes, with a k0 of 1.03x10- 3 cm s- 1. The sterilisation for the real application of sensors in the biomedical field is a critical point, the electrodes were submitted to standard UV light treatment showing to be reliable compared to PLA in the determination of uric acid (30-500 mu M) and sodium nitrite (0.1-5 mM) within synthetic urine using differential pulse voltammetry and chronoamperometry techniques. A sensitivity and LOD for uric acid of 25.7 mu A mu M-1 and 0.27 mu M, and 52.6 mu A mM-1 and 2.69 mu M for nitrite were obtained within synthetic urine, respectively. The re-useability of the electrodes was also tested for the detection of uric acid, showing that the electrode could be used up to 10 times before a significant decrease in the results was observed. We demonstrate that a new conductive rPETg with superior electrochemical performance has a prominent place within the development of additive manufacturedprinted healthcare sensors due to its ability to be sterilised and re-used, low solution ingress, and its potential to tackle rising costs and plastic waste problems within the healthcare sector.

The production, optimisation, physicochemical, and electroanalytical characterisation of a low-cost electrically conductive additive manufacturing filament made with recycled poly(lactic acid) (rPLA), castor oil, carbon black, and graphite (CB-G/PLA) is reported. Through optimising the carbon black and graphite loading, the best ratio for conductivity, low material cost, and printability was found to be 60

This review aims to provide an overview of sustainable approaches that can be incorporated into well-known procedures for the development of materials, pre- and post-treatments, modifications, and applications of 3D-printed objects, especially for fused filament fabrication (FFF). Different examples of conductive and non-conductive bespoke filaments using renewable biopolymers, bioplasticizers, and recycled materials are presented and discussed. The main final characteristics of the polymeric materials achieved according to the feedstock, preparation, extrusion, and treatments are also covered. In addition to recycling and remanufacturing, this review also explores other alternative approaches that can be adopted to enhance the sustainability of methods, aiming to produce efficient and environmentally friendly 3D printed products. Adjusting printing parameters and miniaturizing systems are also highlighted in this regard. All these recommended strategies are employed to minimize environmental damage, while also enabling the production of high-quality, economical materials and 3D printed systems. These efforts align with the principles of Green Chemistry, Sustainable Development Goals (SDGs), 3Rs (Reduce, Reuse, Recycle), and Circular Economy concepts.

In this overview, we explore the electroanalytical determination of the poisoner's poison: thallium. Thallium was named after the Greek word ''thallos,'' meaning ''green shoot'' or ''twig,'' due to its bright green spectral emission lines. It is toxic, tasteless, odourless and dissolves into water, and has been used by murderers as a challenging poison to detect and there is the need for the analytical determination of thallium. Laboratory based analytical instrumentation provide a routine methodology to measure thallium, but there is scope to develop in-the-field analytical measurements that are comparable to laboratory equipment and in some cases, they can provide even more sensitive analytical approaches. Electrochemistry can support such endeavours, where instrumentation are readily portable where electroanalytical sensors provide highly selective and sensitive outputs but yet are economical to support on-site analysis. In this review, we provide an electroanalytical overview of the current research directed toward the measurement of thallium and offer insights to future research.

Among the existing metal-oxide gas sensors, cobalt oxide has the flexibility to revise the morphology through Cr-dopant to enhance sensing properties. Sensitive-surface of the chromium-doped cobalt oxide has proven its effective sensing nature to hydrogen sulfide gas. Interestingly, chromium-dopant increases the surface area, leading to particle size reduce and produces the more active sites for gas molecules. Also, the dopant creates impurity phases on the material which extends the sites for more reaction. To confirms these characteristics, the photoluminescence spectra showed intense peak that mimics the faster transport of electron to accelerate the sensing reaction. According to sensing measurement, the doped sensor is showing three-fold increase of response to 10 ppm gas and also, it detects the 2 ppm efficiently. The doped sensor warrants the stable response to gas due to higher reproducibility. Notably, the doped sensor detects the 1 ppm of gas at 120s and recovery itself around 200s. The doped sensor imparts response at room-temperature, affirming sensitive-surface. The doped sensor has shown the capable under humidity environment through response.

The combination of multi-walled carbon nanotubes (MWCNT) and carbon black (CB) is presented to produce a high-performance electrically conductive recycled additive manufacturing filament. The filament and subsequent additively manufactured electrodes were characterised by TGA, XPS, Raman, and SEM and showed excellent low-temperature flexibility. The MWCNT/CB filament exhibited an improved electrochemical performance compared to an identical in-house produced bespoke filament using only CB. A heterogeneous electrochemical rate constant, k_obs^0 of 1.71 (± 0.19) × 10−3 cm s−1 was obtained, showing an almost six times improvement over the commonly used commercial conductive CB/PLA. The filament was successfully tested for the simultaneous determination of acetaminophen and phenylephrine, producing linear ranges of 5–60 and 5–200 μM, sensitivities of 0.05 μA μM−1 and 0.14 μA μM−1, and limits of detection of 0.04 μM and 0.38 μM, respectively. A print-at-home device is presented where a removable lid comprised of rPLA can be placed onto a drinking vessel and the working, counter, and reference components made from our bespoke MWCNT/CB filament. The print-at-home device was successfully used to determine both compounds within real pharmaceutical products, with recoveries between 87 and 120