Electrochemical Response Research Articles

EIS Behavior of Polyethylene + Graphite Composite Considered as an Approximation to an Ensemble of Microelectrodes

The electrical percolation of alternating current through two-phase polyethylene/graphite composite electrodes with different contents of graphite microparticles immersed in aqueous KCl solutions has been studied. Above the graphite content of the first percolation threshold, the electrochemical impedance response of this electrode is associated with an equivalent circuit of resistance Ru in series with a constant phase element (CPE). An insulator material + conducting filler model is proposed in which the electroactive surface is considered as the intersection of the percolation cluster through the solid and the cluster associated with the interfacial region. CPE is analyzed assuming a distribution of microcapacitors of the graphite particles in contact with the dielectric solution and inside the dielectric polymeric phase.

Voltammetric Sensor Based on Titania Nanoparticles Synthesized with Aloe vera Extract for the Quantification of Dithiophosphates in Industrial and Environmental Samples

In this work, TiO2 spherical nanoparticles with a mean diameter of 10.08 nm (SD = 4.54 nm) were synthesized using Aloe vera extract. Rutile, brookite, and anatase crystalline phases were identified. The surface morphology of a carbon paste electrode does not change in the presence of nanoparticles; however, the surface chemical composition does. The voltammetric response to dicresyl dithiophosphate was higher when the electrode was modified with TiO2 nanoparticles. After an electrochemical response study from pH 1.0 to 12.0, pH 7.0 was selected for the electroanalysis. The electroactive area of the modified sensor was 0.036 cm2, while it was 0.026 cm2 for the bare electrode. The oxidation process showed mixed adsorption-diffusion control. The charge transfer resistance of the modified sensor (530.1 Ω, SD = 4.08 Ω) was much lower than that of the bare electrode (4298 Ω, SD = 8.53 Ω). The linear quantitative range by square wave voltammetry was from 5 to 150 μmol/L, with a limit of detection of 1.89 μmol/L and a limit of quantification of 6.26 μmol/L under optimal pulse parameters of 50 Hz frequency, 1 mV step potential, and 25 mV pulse amplitude. The sensor response was repeatable and reproducible over 30 days. The results on real flotation and synthetically contaminated soil samples were statistically equivalent to those obtained by UV-vis spectrophotometry. A dithiocarbamate showed an interfering effect on the sensor response to dithiophosphate.

In-situ Profiling of Environmental Hazardous Sulfamethoxazole in Aquatic and Artificial Saliva samples Using Perovskite Structured Bismuth Ferrite Incorporated Halloysite Nanotubes

Sulfamethoxazole (SMX), a widely used antibiotic, poses significant environmental and health risks due to its persistence and mobility in water systems, potentially leading to antibiotic resistance and ecological harm. Herein, we developed an electrochemical sensor based on Bismuth Ferrite (BiFeO3)/Halloysite Nanotube (BFO/HNT) composite for sensitive and selective SMX detection. The BFO/HNT composite was synthesized via a hydrothermal method and comprehensively characterized using EDS mapping, HRTEM, XRD, FT-IR, and XPS analysis. The BFO/HNT composite enhances the sensor’s performance due to its unique properties, such as increased electrochemical surface area (ECSA) and efficient electron transfer capability. The B-cation (Fe) in the BiFeO3 matrix plays a crucial role in boosting the electrochemical response by facilitating redox reactions. In addition, the HNTs provide a high surface area and excellent adsorption capabilities, which improve the sensor’s sensitivity by facilitating better interaction with SMX molecules. As the results, the prepared sensor demonstrates an impressive linear detection range of 0.01 to 2 µM and 22 to 122 µM, with a detection limit as low as 0.017 µM. Practical applications were validated by detecting SMX in tap water and artificial saliva, achieving high recovery rates of 98.87 % and 99.11 %.

Smart modulation by bifunctional probes PNAI@Co3O4/Au NPs of the light/electric response of Au-Ag NCs to realize the dual-channel precise detection of AOH

Mycotoxin contamination currently poses a significant concern and presents a major challenge to global food safety management. In this research, gold‑silver nanoclusters (Au-AgNCs) were utilized as platforms for electrogenerated chemiluminescence (ECL) and electrochemical (EC) responses, while polyaniline-coated cobalt tetraoxide and gold (PANI@Co3O4/AuNPs) served as bifunctional probes with intelligently modulated light/electric signals to develop a dual mode adaptor sensor for sensitive detection of alternariol (AOH). The sensor's benefits are evident in three areas:(1) Bandgap modulation allows Au-Ag to exhibit enhanced light/electric response;(2) PANI@Co3O4/AuNPs exhibit both ECL quenching effects and the capability to activate KHSO5, along with improved electrical conductivity, which collectively improves the sensor's detection performance;(3) The dual-channel signal outputs significantly reduce the risk of false detections. Testing results indicated that the ECL and EC sensors performed exceptionally well across AOH concentration ranges of 0.001–100 ng/mL and 0.01–1000 ng/mL, with detection limit of 0.803 pg/mL and 0.378 pg/mL, respectively.

Ultrasound-assisted synthesis of Co(OH)2 nanoflowers and nanosheets as battery-type cathode for high-performance supercapacitors

The depletion of traditional energy resources and the escalating environmental concerns have compelled researchers to pursue green energies, among which the supercapacitors possess a crucial function in electrochemical energy storage systems. In this study, the Co(OH)2 nanoflowers and Co(OH)2 nanosheets have been respectively synthesized utilizing a safe and facile ultrasound-assisted method in the solvent with different pH values, and the product is denoted as Co(OH)2-7.5 and Co(OH)2-9.5, accordingly. The Co(OH)2-7.5 exhibited a specific surface area of 188.3 m2 g, significantly greater than that of Co(OH)2-9.5. Additionally, these Co(OH)2 electrode materials showed battery-type electrochemical response, and the Co(OH)2-7.5 presented an impressive specific capacity of 371.6 C g−1. When integrated into a hybrid supercapacitor (HSC) device with activated carbon (AC) as anode, the device exhibited an exceptional cycling stability after 10000 cycles at 10 A g−1. Furthermore, the Co(OH)2-7.5//AC HSC delivered an impressive energy density (De) of 30.2 W h kg−1 at the power density (Dp) of 888.6 W kg−1, and this De surpassed the 26.4 W h kg−1 of Co(OH)2-9.5//AC HSC. The Co(OH)2 in this work shows good application potential in the field of supercapacitors. The straightforward and efficient synthesis technique can be further applied to the synthesis of many other transition metal hydroxides with remarkable electrochemical properties.

Portable Electrochemical Immunosensor Based on a Gold Microblobs-Optimized Screen-Printed Electrode for SARS-CoV-2 Diagnosis

The development of biosensors for determining the most diverse biomolecules is a constant focus of many research groups. There is a latent need to propose sensors that combine portability, simple measurements, and good analytical performance. Here, we propose an electrochemical immunosensor that is fully portable and energy-independent for diagnosing antibodies against SARS-CoV-2 (the virus that causes COVID-19). Initially, disposable screen-printed carbon electrodes (SPEs) were covered by gold microblobs (AuMBs), which were synthesized amperometrically from Au3+ ions. Then, the SPE-AuMBs were coated with cysteamine, which allowed the N-hydroxysuccinimide-activated SARS-CoV-2 antigen (spike protein) to be immobilized. The antigen-activated electrode was used to detect COVID-19 antibodies from current measurements obtained by differential pulse voltammetry. The AuMBs synthesis time was optimized, and the presence of gold structures improved the electrochemical responses of the SPE. It was possible to quantitatively determine antibodies in the concentration range of 0.25 to 10 µg mL−1. This range includes concentrations found in biological fluids from patients at any stage of the disease. An analysis took approximately the same time as traditional rapid nasal tests (20 min) and costed less, considering all the steps necessary to prepare a disposable antigen-functionalized SPE.

Hierarchical graphene oxide/nano-pyramidal stainless-steel on nickel foam substrate: A flexible electrochemical sensor for arsenic compound detection

The organoarsenic compound roxarsone (ROX) is added to chicken feed to enhance nutritional value. Although organic arsenic is generally less harmful than inorganic arsenic, concerns have arisen about its potential to transform into inorganic forms when excreted in animal waste, raising environmental and human health concerns. The potential dangers of long-term ROX exposure require reliable methods for the detection of the target analyte. In the current study, fabricated nanoscale graphene oxide (GO)/stainless steel (SS) pyramidal structures on nickel foam (NF) is used as an electrode in the electrochemical detection of ROX. The proposed sensor was shown to outperform existing devices in terms of electrochemical activity, resulting in a wider linear range of detection for ROX (0.05–83.15 µM) and lower detection limit (LOD) (0.006 µM). Further, real sample analysis on water and meat samples confirmed the feasibility of the proposed GO/SS/NF sensor for the real-time detection of ROX in real-world applications. This research provides evidence to support the development of heterojunctions to improve ion transport channels and surface-active sites to promote ion mobility to enhance electrochemical responses.

MOF derived ZnCo2O4@nitrogen-doped carbon as an electrochemical sensor for simultaneous detection of acetaminophen and p-aminophenol

In this study, a rapid and sensitive electrochemical sensor (ZnCo2O4@NC) based on metal-organic frame (MOF)-derived metal oxide material (ZnCo2O4) and chitosan derived nitrogen-doped carbon material (NC) was successfully constructed for the simultaneous determination of acetaminophen (APAP) and p-aminophenol (PAP). A series of electrochemical experiments proved that the MOF derived ZnCo2O4@NC composite has excellent electrochemical response to APAP and PAP in the phosphate buffer saline (PBS) (pH 7.0). The current response varies linearly with the increase of APAP concentration in the range of 8.0 μmol L−1 to 520 μmol L−1 and PAP concentration in the range of 6.0 μmol L−1 to 420 μmol L−1. The sensitivity and limit of detection (LOD) of ZnCo2O4@NC for APAP and PAP detection are 0.1024 and 0.2749 μA μmol L−1 cm−2, 0.0608 and 0.2489 μmol L−1, respectively. The ZnCo2O4@NC composite modified electrode exhibits good selectivity, reproducibility and stability. Additionally, in the detection for acetaminophen sustained-release tablets, the recovery rates of APAP are in the range of 90.00 % –100.00 %. The theoretical content is consistent with our detection results, showing that this method has good accuracy in actual sample analysis. This study provides an innovative idea to improve electrochemical performance of simultaneous detection of acetaminophen and p-aminophenol through the comprehensive strategy of structural design, heteroatom doping.

Detection of the stimulant clobenzorex using voltammetry and screen-printed electrodes: A simple and fast screening method for application in seized samples and oral fluid of drivers

Clobenzorex (CBZ) is a stimulant drug, recognized for its anorectic potential, legally used in some countries for obesity treatment. However, CBZ is banned in much of the world and has been often used illegally by drivers needing to stay alert for extended periods. Therefore, the rapid identification of CBZ in forensic samples is of paramount importance for public health and safety. In this context, we introduce an innovative electroanalytical screening method for detecting CBZ in seized tablet samples and human oral fluid using voltammetry with a graphite screen-printed electrode (SPE-Gr). The electrochemical detection was optimized in phosphate buffer solution (0.1 mol L−1, pH 7.0) using square wave voltammetry (SWV). The SPE-Gr combined with SWV exhibited a good stability of the electrochemical responses for CBZ detection, with a relative standard deviation of less than 5% across different days (N = 5) and using different SPEs (N = 3). A linear detection range of 2.5–100.0 μmol/L (R2 = 0.992) was achieved, with a low limit of detection (LOD) of 0.32 μmol L−1. Interference studies with other illicit drugs and adulterants confirmed the selectivity of the proposed method for CBZ detection. In addition, the presence of CBZ in seized tablet samples and authentic oral fluids, collected from drivers, was detected and identified using the proposed method, which results were also confirmed by HPLC-MS. Consequently, integrating SPE-Gr with SWV offers a reliable, rapid, sensitive, selective, reproducible, and direct approach for the preliminary qualitative and quantitative analysis of CBZ in forensic contexts. Furthermore, the proposed method provides an efficient oral fluid test for CBZ screening in drivers under the influence of drugs.

A novel electrochemical sensor based on aspartic acid polymer and carbonized-ZIF-67 for rapid sensing of arbutin

A novel electrochemical sensor modified by aspartic acid polymer and carbonized-ZIF-67 was prepared for arbutin detection. ZIF-67 was synthesized and carbonized, and then used as the substrate supporting of electrochemical sensor. Carbonized-ZIF-67 had a large specific surface and good electrical conductivity, which provided large electroactive area and promoted the electron transfer at the sensing interface. Aspartic acid polymer was prepared by cyclic voltammetry. Aspartic acid polymer could effectively absorb arbutin, resulting in the preconcentration of arbutin on sensor surface. Benefiting from the synergistic effect between carbonized-ZIF-67 and aspartic acid polymer, the prepared electrochemical sensor exhibited sensitive electrochemical response for arbutin. Under the optimum conditions, the electrochemical sensor achieved a wide linear range in the range from 5 to 110 μmol/L and a low detection limit of 0.41 μmol/L for arbutin. In practical application, the electrochemical sensor was employed to detect arbutin in green tea and whitening cream samples, exhibiting satisfactory recovery rates. With the outstanding features of easy operation, rapid response and high sensitivity, the prepared electrochemical sensor provided a convenient and effective tool for arbutin detection.

Schiff base substituted non-peripheral symmetrical cupper, cobalt, and manganese phthalocyanines: Synthesis, design, electrochemistry, and spectroelectrochemistry

Novel CoII (nANTHCoPc), CuII (nANTHCuPc), and MnIIICl (nANTH-MnClPc) phthalocyanines were obtained by substituting the 3-(4-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylimino)methyl)phenoxy) Schiff base compound (nANTHOH) obtained by the acid-catalyzed condensation reaction of 4-aminoantipyrine and 4-hydroxybenzaldehyde at non-peripheral positions. By using various spectroscopic techniques, (NMR, MALDI-TOF, FT-IR, and UV–Vis), the structures of green-colored phthalocyanine compounds and precursor phthalonitrile compounds were identified. The electrochemical responses of cobalt (II) (nANTHCoPc), cupper (II) (nANTHCuPc), and manganese (III) (nANTH-MnClPc) phthalocyanines were determined, and their redox responses were analyzed based on the different metal centers. The results indicated that using redox-active Co2+ and Mn3+ cations instead of Cu2+enhanced the redox richness of the complexes due to the observation of extra metal-based electron transfer reactions in addition to the Pc-based ones. In-situ spectroelectrochemical analyses of the complexes were used to support the peak assignments of the redox processes and the spectrum and color of the electrogenerated species during the redox reactions. Supported these redox mechanisms. Multi-electron transfer processes and distinct color changes during these processes indicate the possible usage of these complexes in various electrochemical and opto-electrochemical processes. Metal-based electron transfer reactions illustrated different spectral changes than those of the Pc-based ones, and these spectral changes significantly differed the color of the anionic and cationic species.

Development of an electrochemical sensor modified with gold nanoparticles for detecting fumonisin B1 in packaged foods.

Fumonisin B1 (FB1) is naturally present in the environment and can easily contaminate packaged foods during processing, storage and transportation, thus posing a threat to human health. We have developed an enzyme-free FB1 detector for the detection of packaged foods, which provides rapid and sensitive detection of FB1 in food. Gold nanoparticles (AuNPs; 5-10 nm) were uniformly dispersed on screen-printed electrodes, which acted as an excellent catalytic oxidizer. The surface structure of the modified electrode was characterized using scanning electron microscope and X-ray photoelectron spectroscopy. Differential pulse voltammetry demonstrated a good linear electrochemical response towards FB1 at concentrations ranging from 1 ng L-1 to 1 mg L-1 with a detection limit of 0.08 ng L-1. We employed the AuNPs-SPE sensor to detect FB1-spiked packaged meat products achieving recovery rates ranging from 89.7% to 113.3%.

A nonlinear phase-field model of corrosion with charging kinetics of electric double layer

Abstract A nonlinear phase-field model is developed to simulate corrosion damage. The motion of the electrode-electrolyte interface follows the usual kinetic rate theory for chemical reactions based on the Butler-Volmer equation. The model links the surface polarization variation associated with the charging kinetics of an electric double layer (EDL) to the mesoscale transport. The effects of the EDL are integrated as a boundary condition on the solution potential equation. The boundary condition controls the magnitude of the solution potential at the electrode$-$electrolyte interface. The ion concentration field outside the EDL is obtained by solving the electro$-$diffusion equation and Ohm's law for the solution potential. The model is validated against the classic benchmark pencil electrode test. The framework developed reproduces experimental measurements of both pit kinetics and transient current density response. The model enables more accurate information on corrosion damage, current density, and environmental response in terms of the distribution of electric potential and charged species. The sensitivity analysis for different properties of the EDL is performed to investigate their role in the electrochemical response of the system. Simulation results show that the properties of the EDL significantly influence the transport of ionic species in the electrolyte.

A cost-effective method for the sensitive detection of levofloxacin using a 3D composite electrode composed of nail polish, graphite and aluminium oxide.

The potential impact on human health and the environment has spurred significant interest in detecting and quantifying pharmaceutical compounds across various matrices, from environmental to biological samples. Here, we present an electrochemical approach for determining levofloxacin in drug, synthetic urine, water, and breast milk samples. An affordable sensor was constructed using 3D printing and composite material based on nail polish, graphite, and aluminum oxide. The conductive composite material was characterized spectroscopically, electrochemically, and by imaging techniques. Subsequently, an electrochemical method based on square wave voltammetry was optimized and applied. The method exhibited good sensitivity (5.11 ± 0.0912 μA L μmol-1 cm-2) and enhanced stability (RSD = 7.2%), with electrochemical responses correlating with the concentration of levofloxacin in the samples tested, yielding recovery values in the range of 98 to 111%. The developed method demonstrated a robust linear working range from 2 to 100 μmol L-1 and a nanomolar detection limit of 128 nmol L-1, rendering it suitable for quantitative analysis. The sensor also shows promise as a platform for the sensitive detection of pharmaceutical compounds, contributing to greater safety and sustainability in these domains.

AuNPs@MoS2 functionalized copper metal organic framework for boosting electrocatalytic glucose oxidation

A novel non-enzyme glucose sensor based on functionalized copper metal–organic framework composite material, AuNPs@MoS2/Cu-MOF, was developed for rapid glucose analysis. Cu-MOF nanomaterial was prepared via a hydrothermal method, followed by the surface loading of core–shell structured AuNPs@MoS2 to synthesize AuNPs@MoS2/Cu-MOF composite material. Consequently, a novel gold nanoparticle @ molybdenum disulfide/copper metal–organic framework (AuNPs@MoS2/Cu-MOF/GCE) non-enzyme glucose sensor was constructed. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray powder Diffraction (XRD) was used to verify that the non-enzyme glucose sensor had been constructed effectively. Traditional electrochemical characterization methods were employed to study the electrocatalytic performance of the AuNPs@MoS2/Cu-MOF/GCE sensor and its catalytic oxidation of glucose. The experimental results demonstrated a good linear correlation between the concentration of glucose and the peak current within the range of 0.05–14.85 mM, with a detection limit of 16.7 μM. The AuNPs@MoS2/Cu-MOF/GCE sensor exhibited rapid electrochemical response to glucose (within 0.5 s), along with long-term stability and excellent selectivity. This is because Cu(II) in Cu-MOF can serve as active sites for the electrocatalytic oxidation of glucose, while the core–shell structure of AuNPs@MoS2 with excellent conductivity can lower the energy barrier in the reaction, further accelerating this catalytic reaction. The AuNPs@MoS2/Cu-MOF/GCE sensor is cost-effective, easy to operate, and suitable for accurate rapid quantification of glucose.

Poly-methionine/graphitic carbon nitride modified screen-printed electrodes: A metal-free, bio-interface for tryptophan sensing

Tryptophan (TRP) is an essential amino acid needed for the growth and proper functioning of the human body. A balanced intake of TRP-rich food products is essential to meet the daily requirements. As both low and high levels of TRP are associated with clinical disorders, an optimum amount of TRP intake is critical. Hence, developing a method to efficiently detect TRP in food and nutritional supplements is essential. Accordingly, this study reports the electrochemical detection of TRP using poly-methionine/graphitic carbon nitride modified screen-printed electrode (gCN.Meth|SPE). To our knowledge, this study is the first attempt to decipher the electrodeposition of gCN.Meth on a conducting substrate through a systematic analysis of the electro-functionalized gCN.Meth surface using XRD, FT-IR, HR-SEM, EDX, and AFM. The synergistic benefits of both the gCN and conducting poly(methionine) resulted in augmented electrochemical performance exhibiting a pronounced TRP oxidation peak in both cyclic voltammetry (CV) and square wave voltammetry (SWV). The improved electrochemical response can be ascribed to the specific interactions between the TRP and gCN through π- π interactions and hydrogen bonding and electrostatic interaction between TRP and methionine. This facilitated interaction resulted in the electro-catalytic oxidation of TRP with a negative potential shift of 0.126 V and a 16.6-fold increase in the current response compared to unmodified SPE. The gCN.Meth|SPE exhibited a 25.12 times higher sensitivity compared to bare SPE, with a linear response in the concentration ranges of 1.0–300.0 μM and a low detection limit of 29.9 nM. The interference study further indicated that gCN.Meth-modified SPEs is highly effective for the precise and reliable detection of tryptophan in real samples.

Graphene/PEDOT/Ni-Based electrochemical Non-Enzymatic glucose sensor

Compared to enzymatic glucose sensors, non-enzymatic glucose sensors offer significant advantages in sensitivity, stability, and cost. In this study, a green and simple electrochemical method was employed to prepare an electrochemical non-enzymatic glucose sensor based on graphene/PEDOT/Ni materials. The modified electrode was characterized using scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of glucose on the modified electrode was investigated, and the results indicated that the sensor exhibited a good electrochemical response to glucose. Experimental conditions were optimized, and under the optimal conditions, the sensor showed a good linear relationship with glucose concentration in the range of 0.0001 to 7 mM, with a detection limit of 0.012 μM. The sensitivity was 1561 μA·mM−1·cm−2, demonstrating excellent reliability, stability, and accuracy.

Simultaneous electro-chemical detection of Pb and Fe by copper-modified carbon paste electrode in the portion of soil

A carbon graphite and copper powder paste electrode (CPE-Cu) was successfully designed as a working electrode for electrochemical analysis. The structural characteristics of this electrode were revealed by X-ray diffraction. Voltammetric techniques and electrochemical impedance spectroscopy were used to assess the electroactivity of the proposed working electrode. X-ray diffraction showed that the composite material has a slightly different crystalline structure to pure graphite, since the copper modification influenced the angles of reflection so that they fluctuated towards slightly larger values. The study of the electrochemical behaviour of the CPE-Cu electrode using cyclic voltammetry showed that the redox phenomena at the electrode surface are almost reversible. Analysis of the soil portion using cyclic voltammetry showed that lead (II) and iron (II) showed current peaks at potentials −0.36 V and +0.12 V respectively. These potentials were confirmed by square-wave voltametry. Cyclic voltammetry and square wave voltammetry showed linearity between the portion of soil in the soil and the electrochemical response. In addition, the study of the effect of the scanning speed showed that the reactions at the working electrode are controlled by a diffusion phenomenon at the surface of the working electrode. Electrochemical impedance spectroscopy showed that the electrode material had a low resistance to charge transfer, with a complete analysis of around 80 ohm.cm2. The heavy metals Cd2+, Pb2+ and Fe2+ were detected simultaneously at trace levels. Calculations of the detection limits for Pb2+ and Fe2+ gave 0.709 ppm and 0.821 ppm respectively. At the end of this work, it can be said that the proposed sensor can be used as an instrument for monitoring the metals studied, as the detection limits were relatively low despite the complexity of the detection medium (portion of soil).

Electrochemical Detection of Tobramycin Resistance in Escherichia Coli

The development of techniques to detect the presence of resistance in pathogens are urgently needed to face the deadly spread of multi-drug-resistant bacteria. The present work presents the electroanalytical quantification of tobramycin (TOB) retention in susceptible and resistant bacterial strains of Escherichia coli. The electrochemical characterization of TOB demonstrates the suitability of electrochemistry for drug detection. Differential pulse voltammetry (DPV) parameters were optimized by full factor experimental designs, which increased two-times the electrochemical current response, improving the overall sensitivity of the method. The developed assay was able to differentiate between resistant and susceptible E. coli strains within 15 min. The demonstrated methodology is expected to be applicable to both drug efflux-mediated and drug uptake inhibition-mediated resistant bacteria. Because these two mechanisms represent the most predominant reasons for drug resistance in bacteria, the reported method has a strong potential to be a reliable, fast, and cost-efficient alternative for antibiotic resistance detection.

The Influence of 3D Printing Methods and Materials on the Response of Printed Symmetric Carbon Supercapacitors

We compare the electrochemical response and intrinsic limitations of symmetric carbon-based supercapacitors using two 3D-printing techniques, vat polymerization (Vat-P) and fused deposition modelling (FDM). Two cell types were made in this study, one with metallized Vat-P-printed current collectors, the other with PLA (polylactic acid) FDM-printed current collectors in a similarly designed printed coin cell. Carbon-based electrode slurry (various combinations of SWCNT, GNP, Super-P, PVDF) and aqueous 6 M KOH electrolyte were used in these cells. We demonstrate the influence of internal resistance of each 3D-printing method by direct comparison of cyclic voltammetry and galvanostatic charge-discharge tests. The metallized conductive Vat-P cells display better conductivity and more ideal rectangular cyclic voltammetry response but suffer from poor cycle life in initial experiments (∼5,000 charge-discharge cycles before losing all specific capacitance). The FDM current collector cells using graphite-containing PLA materials have poorer conductivity, less ideal cyclic voltammetry curves, and are structurally less robust and partially porous, but offer very stable cycle life for supercapacitor cells retaining most of their specific capacitance after 100,000 charge-discharge cycles. The cycle life of the metallized Vat-P cells are improved by reducing the voltage window to 0.2–0.7 V to limit metal delamination and using Super-P and PVDF additives.