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A light-addressable potentiometric sensor (LAPS) is a semiconductor-based sensor platform for sensing and imaging of various chemical species. Being a potentiometric sensor, no faradaic current flows through its sensing surface, and no electrochemical reaction takes place in the course of LAPS measurement. In this study, a four-electrode system is proposed, in which a LAPS is combined with the conventional three-electrode electrochemical system. A LAPS is included as the fourth electrode for potentiometric sensing and imaging of the target analyte in the course of an electrochemical reaction taking place on the surface of the working electrode. The integrated system will be useful for analyzing dynamic processes, where both the electrochemical process on the electrode surface and the ion distribution in the solution need to be simultaneously investigated. Different grounding modes of control circuits that can simultaneously conduct potentiostatic/galvanostatic polarization and LAPS measurement are designed, and their functionalities are tested. The interference between polarization and LAPS measurement will also be discussed. [ABSTRACT FROM AUTHOR]

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems. [ABSTRACT FROM AUTHOR]

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Electrochemical measurements are vital to a wide range of applications such as air quality monitoring, biological testing, food industry, and more. Integrated circuits have been used to implement miniaturized and low-power electrochemical potentiostats that are suitable for wearable devices. However, employing modern integrated circuit technologies with low supply voltage precludes the utilization of electrochemical reactions that require a higher potential window. In this paper, we present a novel circuit architecture that utilizes dynamic voltage at the working electrode of an electrochemical cell to effectively enhance the supported voltage range compared to traditional designs, increasing the cell voltage range by 46% and 88% for positive and negative cell voltages, respectively. In return, this facilitates a wider range of bias voltages in an electrochemical cell, and, therefore, opens integrated microsystems to a broader class of electrochemical reactions. The circuit was implemented in 180 nm technology and consumes 2.047 mW of power. It supports a bias potential range of 1.1 V to −2.12 V and cell potential range of 2.41 V to −3.11 V that is nearly double the range in conventional designs. [ABSTRACT FROM AUTHOR]

A new Mg-4Zn X Ti-6Al-4V (TC4, of 0, 1, and 3 wt.%) alloy was successfully fabricated by a simple and low-cost gravity casting method and heat treatment at 150 °C for 24 h. The composite was examined by XRD, uniaxial tests, FESEM/EDS, potentiostat/EIS, and immersion tests for the material's microstructures, mechanical properties, electrochemical characteristics, and corrosion resistance. Experimental results indicate that heat treatment enables the precipitation of Zn along the Mg grain boundaries and drives the co-precipitation of Al around the TC4 particles and nearby grain boundaries. Uniaxial tensile tests reveal that TC4 reinforces the Mg-Zn matrix material with higher elastic modulus, ultimate tensile stress, and toughness. The heat treatment further enhanced these mechanical properties. Electrochemical tests show that 1 wt.% TC4 composite exhibits the highest open circuit potential among all tested samples, which implies the 1 wt.% TC4-added Mg-Zn is better resistant to the oxidation of the essential metals Mg, Zn, and Al. The immersion tests in the HBSS solution further show that the 1 wt.% TC4 composite has the lowest rise of pH values after 14 days, and EDS for the corroded surface signifies that Mg is the main element vulnerable to oxidation by corrosion. [ABSTRACT FROM AUTHOR]

A potentiostat is necessary to achieve accurate control of potentials in an electrochemical cell for most electroanalytical techniques. While lab-built potentiostats with specific design objectives such as low manufacturing cost and field portability have been developed in recent years, there remain a lack of accessible potentiostats that prioritize measurement quality, user-friendliness, and adaptability for general laboratory use. In response, we present Opensens, an open-source, multi-purpose potentiostat that can function independently or as part of an instrument suite. The Opensens can perform accurately the Fe3+/Fe2+ redox couple experiments as well as the ascorbic acid (AA) detection comparing with the commercial apparatus. [ABSTRACT FROM AUTHOR]

In this paper, a wireless potentiostat code-named ElectroSense, for interfacing of wearable electrochemical biosensors, will be presented. The system is devoted to non-invasive monitoring of glucose in wearable medical applications. Differently from other potentiostats in literature, which use digital-to-analog converters (DACs) as discrete components or integrated in high-end microcontrollers, in this work the pulse width modulation (PWM) technique is exploited through PWM-DAC approach to generate signals. The ubiquitous presence of integrated PWM peripherals in low-end microcontrollers, which generally also integrate analog-to-digital converters (ADCs), enables both the generation and acquisition of read-out signals on a single cheap electronic device without additional hardware. By this way, system's production costs, power consumption, and system's size are greatly reduced with respect to other solutions. All these features allow the system's adoption in wearable healthcare Internet-of-things (IoT) ecosystems. A description of both the sensing technology and the circuit will be discussed in detail, emphasizing advantages and drawbacks of the PWM-DAC approach. Experimental measurements will prove the efficacy of the proposed electronic system for non-invasive monitoring of glucose in wearable medical applications. [ABSTRACT FROM AUTHOR]

The self-discharge rate is an important parameter to assess the quality of lithium-ion batteries (LIBs). This paper presents an accurate, efficient, and comprehensive method for measuring and understanding the self-discharge behaviour of LiB cells, considering factors such as temperature and cell to cell variability, as well as underlying electrochemical mechanisms. A method for precise potentiostatic self-discharge measurement (SDM) is demonstrated that is validated by measuring 21 commercial cylindrical 4.7 Ah cells at a state of charge (SoC) of 30%. The self-discharge current ranges between 3 and 6 μA at 23 °C, with an experimental noise level of 0.25 μA. At higher temperatures of 40 °C the self-discharge current increases to 97 μA. The temperature coefficient of voltage (TCV) is experimentally obtained by exposing the cells to a temperature profile with positive and negative step polarities and following the open circuit voltage (OCV) response. Observed TCVs range from +180 µV/K at 40% SoC to −320 µV/K at 0% SoC. For SDM temperature experiments, the cells were set to an SoC with a minimum TCV. From the SDM currents at different temperatures the Arrhenius kinetics and the electrochemical activation energy barrier is determined as 0.94 ± 0.14 eV, indicating chemical side reactions as source of self-discharge. For SDM modelling the electrochemical processes are coupled with a 3D temperature finite element model (FEM) and an electric circuit model resulting in a good overlap with the dynamics and time-constants of the experimental self-discharge curves. The primary challenges addressed are accurately measuring microampere (µA) discharge currents of high-quality cells, reducing measurement time, understanding the temperature dependence of self-discharge, determining activation energy, and demonstrating the applicability and generalization of SDM.

A light-addressable potentiometric sensor (LAPS) is a semiconductor-based sensor platform for sensing and imaging of various chemical species. Being a potentiometric sensor, no faradaic current flows through its sensing surface, and no electrochemical reaction takes place in the course of LAPS measurement. In this study, a four-electrode system is proposed, in which a LAPS is combined with the conventional three-electrode electrochemical system. A LAPS is included as the fourth electrode for potentiometric sensing and imaging of the target analyte in the course of an electrochemical reaction taking place on the surface of the working electrode. The integrated system will be useful for analyzing dynamic processes, where both the electrochemical process on the electrode surface and the ion distribution in the solution need to be simultaneously investigated. Different grounding modes of control circuits that can simultaneously conduct potentiostatic/galvanostatic polarization and LAPS measurement are designed, and their functionalities are tested. The interference between polarization and LAPS measurement will also be discussed.

We describe two operating modes for the same potentiostat, where the redox processes of hydroquinone in a hydrochloric acid medium are contrasted for cyclic voltammetry (CV) as functions of a digital/staircase scan and an analogue/linear scan. Although superficially there is not much to separate the two modes of operation as an end user, differences can be seen in the voltammograms while switching between the digital and analogue modes. The effects of quantization clearly have some impact on the measurements, with the outputs between the two modes being a function of the equivalent-circuit model of the electrochemical system under investigation. Increasing scan rates when using both modes produces higher peak redox currents, with the differences between the analogue and digital modes of operation being consistent as a function of the scan rate. Differences between the CV loops between the analogue and digital modes show key differences at certain points along the scans, which can be attributed to the nature of the electrolyte affecting the charging and discharging processes and consequently changing the peak currents of the redox processes. The faradaic processes were shown to be independent of the scan rates. Simulations of the equivalent-circuit behaviour show differences in the responses to different input signals, i.e., the step and ramp responses of the system. Both the voltage and current steps and ramp responses showed the time-domain behaviour of distinct elements of the equivalent electrochemical circuit model as an approximation of the applied digital and analogue CV input signals. Ultimately, it was concluded that similar parameters between the two modes of operation available with the potentiostat would lead to different output voltammograms and, despite advances in technology, digital systems can never fully emulate a true analogue system for electrochemical applications. These observations showcase the value of having hardware capable of true analogue characteristics over digital systems.

Electrochemical and photoelectrochemical sensors are a rapidly developing field in analytical chemistry. However, commercial systems often lack versatility and affordability, hindering wider adoption. Additionally, the absence of integrated excitation light sources limits their application in photoelectrochemical sensing. Here, we present a highly precise, versatile, affordable measurement system for both electrochemical and photoelectrochemical sensing applications. The system incorporates a three-electrode potentiostat with a synchronized excitation light source. This design enables the system to perform conventional electrochemical measurements like cyclic voltammetry, chronoamperometry, and photoelectrochemical amperometric measurements with controlled light excitation. The developed measurement system operates within a voltage range suitable for a measurable current range of 1 nA to 18 mA, with a high precision of 99%. The excitation source is a monochromatic LED system offering seven distinct wavelengths with digitally controlled intensity via a digital-to-analog converter. Furthermore, an Android-based user interface allows wireless system control via Bluetooth Low Energy. The report also details the construction of a photoelectrochemical experiment using copper (II) oxide nanorods synthesized by the hydrothermal process as the photoactive material employed to test the experiment on a potassium ferricyanide/potassium ferrocyanide solution. This user-friendly system allows broader exploration of electrochemical and photoelectrochemical sensing applications.

Electrochemical sensing is ubiquitous in a number of fields ranging from biosensing, to environmental monitoring through to food safety and battery or corrosion characterisation. Whereas conventional potentiostats are ideal to develop assays in laboratory settings, they are in general, not well-suited for field work due to their size and power requirements. To address this need, a number of portable battery-operated potentiostats have been proposed over the years. However, most open source solutions do not take full advantage of integrated circuit (IC) potentiostats, a rapidly evolving field. This is partly due to the constraining requirements inherent to the development of dedicated interfaces, such as apps, to address and control a set of common electrochemical sensing parameters. Here we propose the PocketEC, a universal app that has all the functionalities to interface with potentiostat ICs through a user defined property file. The versatility of PocketEC, developed with an assay developer mindset, was demonstrated by interfacing it, via Bluetooth, to the ADuCM355 evaluation board, the open-source DStat potentiostat and the Voyager board, a custom-built, small footprint potentiostat based around the LMP91000 chip. The Voyager board is presented here for the first time. Data obtained using a standard redox probe, Ferrocene Carboxylic Acid (FCA) and a silver ion assay using anodic stripping multi-step amperometry were in good agreement with analogous measurements using a bench top potentiostat. Combined with its Voyager board companion, the PocketEC app can be used directly for a number of wearable or portable electrochemical sensing applications. Importantly, the versatility of the app makes it a candidate of choice for the development of future portable potentiostats. Finally, the app is available to download on the Google Play store and the source codes and design files for the PocketEC app and the Voyager board are shared via Creative Commons license (CC BY-NC 3.0) to promote the development of novel portable or wearable applications based on electrochemical sensing. [ABSTRACT FROM AUTHOR]

A new Mg-4Zn X Ti-6Al-4V (TC4, of 0, 1, and 3 wt.%) alloy was successfully fabricated by a simple and low-cost gravity casting method and heat treatment at 150 °C for 24 h. The composite was examined by XRD, uniaxial tests, FESEM/EDS, potentiostat/EIS, and immersion tests for the material’s microstructures, mechanical properties, electrochemical characteristics, and corrosion resistance. Experimental results indicate that heat treatment enables the precipitation of Zn along the Mg grain boundaries and drives the co-precipitation of Al around the TC4 particles and nearby grain boundaries. Uniaxial tensile tests reveal that TC4 reinforces the Mg-Zn matrix material with higher elastic modulus, ultimate tensile stress, and toughness. The heat treatment further enhanced these mechanical properties. Electrochemical tests show that 1 wt.% TC4 composite exhibits the highest open circuit potential among all tested samples, which implies the 1 wt.% TC4-added Mg-Zn is better resistant to the oxidation of the essential metals Mg, Zn, and Al. The immersion tests in the HBSS solution further show that the 1 wt.% TC4 composite has the lowest rise of pH values after 14 days, and EDS for the corroded surface signifies that Mg is the main element vulnerable to oxidation by corrosion.

Wearable technology, such as electronic components integrated into clothing or worn as accessories, is becoming increasingly prevalent in fields like healthcare and biomedical monitoring. These devices allow for continuous monitoring of important biomarkers for medical diagnosis, monitoring of physiological health, and evaluation. However, an open-source wearable potentiostat is a relatively new technology that still faces several design limitations such as short battery lifetime, bulky size, heavy weight, and the requirement for a wire for data transmission, which affects comfortability during long periods of measurement. In this work, an open-source wearable potentiostat device named We-VoltamoStat is developed to allow interested parties to use and modify the device for creating new products, research, and teaching purposes. The proposed device includes improved and added features, such as wireless real-time signal monitoring and data collection. It also has an ultra-low power consumption battery estimated to deliver 15 mA during operating mode for 33 h and 20 min and 5 mA during standby mode for 100 h without recharging. Its convenience for wearable applications, tough design, and compact size of 67x54x38 mm make it suitable for wearable applications. Cost-effectiveness is another advantage, with a price less than 120 USD. Validation performance tests indicate that the device has good accuracy, with an R2 value of 0.99 for linear regression of test accuracy on milli-, micro-, and nano-Ampere detection. In the future, it is recommended to improve the design and add more features to the device, including new applications for wearable potentiostats.

This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed. [ABSTRACT FROM AUTHOR]

In this study, we report a rapid and efficient strategy by cyclic square wave voltammetry (CSWV), a novel voltammetric technique, to detect dopamine (DA) and epinephrine (EP) separately and simultaneously with an unmodified graphene-based integrated electrode. The CSWV method, with high sensitivity and capability of mechanistic study, is achieved by controlling an inexpensive modified open-source potentiostat (MOSP) that has a superior performance comparable to commercial benchtop electrochemical workstations. Based on the different intramolecular cyclization reaction rates of DA and EP depending on pH, the concentration of DA could be derived from the cathodic peak at +0.12 V, and the concentration of EP could be calculated from the negative cathodic peak at −0.26 V. The CSW voltammogram presented that the linear range of both DA and EP was 5–70 μM, with a detection limit of 2.14 μM and 1.94 μM (S/N = 3) at neutral pH, respectively. In addition, the cathodic currents of CSWV were 12.68 and 10.72 times higher than those of cyclic voltammetry (CV) and 1.53 and 1.24 times higher than those of cathodic square wave voltammetry (cSWV). The proposed method showed a strong anti-interference capability and can be applied to detect DA and EP in the real sample (calf serum sample), with a recovery rate in the range of 100.05–108.25%. The introduced electrochemical determination method can provide a promising application prospect for point-of-care testing (POCT) of neurotransmitters. [ABSTRACT FROM AUTHOR]

Iron is one of the trace elements that plays a vital role in the human immune system, especially against variants of SARS-CoV-2 virus. Electrochemical methods are convenient for the detection due to the simplicity of instrumentation available for different analyses. The square wave voltammetry (SQWV) and differential pulse voltammetry (DPV) are useful electrochemical voltammetric techniques for diverse types of compounds such as heavy metals. The basic reason is the increased sensitivity by lowering the capacitive current. In this study, machine learning models were improved to classify concentrations of an analyte depending on the voltammograms obtained alone. SQWV and DPV were used to quantify the concentrations of ferrous ions (Fe + 2 ) in potassium ferrocyanide (K 4 Fe(CN) 6 ), validated by machine learning models for the data classifications. The greatest classifier algorithms models Backpropagation Neural Networks, Gaussian Naive Bayes, Logistic Regression, K-Nearest Neighbors Algorithm, K-Means clustering, and Random Forest were used as data classifiers, based on the data sets obtained from the measured chemical. Once competed to other algorithms models used previously for the data classification, ours get greater accuracy, maximum accuracy of 100% was obtained for each analyte in 25 s for the datasets. [ABSTRACT FROM AUTHOR]

The preparation of ceramic composites based on metal nanopowders allows us to change significantly the thermal characteristics of the ceramic matrix, which is important for the creation of heat-conducting ceramics technology. The work establishes the most efficient method of obtaining nickel nanopowder on a “P-5848” potentiostat by electrolysis of nickel sulfate (NiSO4) with the addition of boric acid (H3BO3), thiourea ((NH4)2CS) and nickel(II) chloride (NiCl2). The synthesis of Ni nanopowder was carried out at a current density from 1.0 to 3.3 A/dm2 and at a temperature of 45–65 °C, where a platinum (Pt) plate was chosen as an anode, and the cathode was specially made of especially pure aluminum (Al). The results of the study showed the synthesis of Ni nanopowder with a size of 55 nm in the form of thin scales. Electrochemical reactions at the cathode and anode are also considered in the work. Several successful experiments were also carried out in the work, which made it possible to develop an economically profitable technology for the synthesis of copper nanopowder by the electrolysis method at 13.3 ampere-hours of current per 1 dm2 of the anode surface at a relatively low temperature of the copper sulfate solution (CuSO4). Copper nanopowder is removed to the bottom of the bath from the anode by impact shaking. An equally successful experiment was carried out, where the cathode was in the form of several copper plates at the distance of 0.8 cm from each other with a voltage between them of 0.775 V, and a current density of 15.3 A/dm2 at the temperature of 54 °С in an electrolyte with 45 % H2SO4, 8 % Na2SO4 and 4 % CuSO4. The work contains tables with initial and final data of all experiments on the synthesis of nanopowders by the electrolysis method. [ABSTRACT FROM AUTHOR]

To move electrochemical sensing technology from the laboratory into point‐of‐care (POC)‐based settings, electrochemical platforms must be cost‐effective, portable, and user‐friendly. Here, we present the comparison of a near‐field communication (NFC) potentiostat with a traditional potentiostat. The NFC potentiostat is roughly the size of a credit card and is wirelessly powered by a smartphone with a user‐friendly application for electrochemical analysis. The proposed system is portable, affordable, and provides analytical capabilities comparable to traditional benchtop potentiostats. Different redox probes were investigated, including ferricyanide, ruthenium hexamine, and hydroquinone, highlighting the ability of the NFC potentiostat to measure a variety of target analytes. In addition, the NFC potentiostat can perform several electrochemical techniques, such as cyclic voltammetry, differential pulse voltammetry, chronoamperometry and square wave voltammetry. The combination of affordable screen‐printed carbon electrodes (SPCE)s with the portable, inexpensive NFC potentiostat highlights this platform's promise towards POC electrochemical sensing applications, particularly for medical diagnostics in rural or low‐income areas. [ABSTRACT FROM AUTHOR]

Electrochemical detection is widely used in biosensing fields, such as medical diagnosis and health monitoring due to its real-time response and high accuracy. Both passive and active electrodes and the corresponding readout circuits have been continuously improved over the past decades. This article summarizes the redox reaction method, state-of-the-art electrode materials, and readout circuits based on the passive three-electrode. The redox-current-based readout circuits are widely used and developed toward multichannel high precision and low power consumption. In terms of active electrodes, this article reviews the development of field-effect transistors (FETs)-based electrochemical detection and readout circuits. In the past decade, the development of organic electrochemical transistors (OECTs) has also enabled more precise electrochemical detection.

The transition of electrochemical sensors from lab-based measurements to real-time analysis requires special attention to different aspects in addition to the classical development of new sensing materials. Several critical challenges need to be addressed including a reproducible fabrication procedure, stability, lifetime, and development of cost-effective sensor electronics. In this paper, we address these aspects exemplarily for a nitrite sensor. An electrochemical sensor has been developed using one-step electrodeposited (Ed) gold nanoparticles (EdAu) for the detection of nitrite in water, which shows a low limit of detection of 0.38 µM and excellent analytical capabilities in groundwater. Experimental investigations with 10 realized sensors show a very high reproducibility enabling mass production. A comprehensive investigation of the sensor drift by calendar and cyclic aging was carried out for 160 cycles to assess the stability of the electrodes. Electrochemical impedance spectroscopy (EIS) shows significant changes with increasing aging inferring the deterioration of the electrode surface. To enable on-site measurements outside the laboratory, a compact and cost-effective wireless potentiostat combining cyclic and square wave voltammetry, and EIS capabilities has been designed and validated. The implemented methodology in this study builds a basis for the development of further on-site distributed electrochemical sensor networks. [ABSTRACT FROM AUTHOR]

Along with many factors, the change in protein tau isoforms, which has an obvious role in the function of microtubules, is an important biomarker of Alzheimer's disease. The aim of this study is to determine the protein Tau‐441 with a portable potentiostat using a practical approach. For this purpose, screen printed electrodes (SPCEs) were first hydroxylated and then functional self‐assembled monolayers were formed on the surface with 3‐aminopropyltriethoxysilane (APTES). Evidence of anti‐Tau being immobilized on to the surface was followed by techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR). The constructed immunosensor showed a linear response within the concentration range of 0.0064–0.8 ng/mL for the target analyte Tau‐441 and the limit of detection was found to be 0.0053 ng/mL. In addition, analytical behaviors such as reproducible measurements and storage life of the developed immunosensor with a portable potentiostat were also investigated. It has been demonstrated that Tau‐441 can be captured with the help of portable device with sensitivity in CSF environment. [ABSTRACT FROM AUTHOR]

Biodegradable materials represent a new class of biocompatible materials with applications in many medical cases where the support must be provided only for a certain period. In this article obtaining of ZnMgY alloy is presented along with some basic characteristic investigations like chemical composition (energy dispersive spectroscopy – EDS), microstructure (optical microscopy – OM and scanning and electron microscopy – SEM), immersion behavior in 10xDPBS (Dulbecco Phosphate Buffer Saline) solution (mass loss and surface degradation), electro-corrosion behavior (potentiostat with a three electrodes cell) and micro-hardness of the experimental alloy compared to cast Zn and ZnMg materials. The results present an improvement of micro-hardness of Zn by alloying with Mg and Y and a modification of corrosion resistance.

The presented design is a low-cost, compact, and open-source USB-controlled platform for biological tissue and electrode-tissue interface electrical measurements, capable of potentiostatic and galvanostatic electrical impedance spectroscopy up to 10 MHz and cyclic voltammetry with voltage compliance of +−8 V and up to 2.4 mA while ensuring tissue-safety conditions. The data acquisition and generation are based on an Analog Discovery 2 platform (Digilent, USA). We provide accuracy analysis and comparisons with a commercially available calibrated impedance analyzer. Impedance measurements are demonstrated on implanted electrodes for neural stimulation and on an isolated ex-vivo calf brain as an example use case of the presented design.

In this research a portable potentiostat was built for electrochemical sensing measurements with three electrodes, specifically SPCEs. The circuit uses a microcontroller as the main controller to manage all activities, starting from adjusting the input voltage for the SPCEs, setting measurement parameters, measuring the resulting current, displaying graphics on the touch screen, sending data to the computer via the USB port, and connecting to the SD card. Measurements and errors with cyclic voltammetry techniques have been compared with commercial potentiostats. The measurement results on a dummy circuit and commercial SPCEs have an accuracy of more than 90% compared to commercial potentiostats. In addition, measurement data can also be saved to an SD card in.CSV format for further purposes. [ABSTRACT FROM AUTHOR]

The role of the electroactive surface area (EASA) and of the non-electroactive surface area (nEASA) was studied to better understand electroactive biofilm's (EAB) growth and performance in four different systems. Those systems consisted in four 1L glass bottles filled with mineral medium and substrates, a stainless-steel cathode and a bioanode. Four different types of bioanode were assembled in order to study the EASA and nEASA role. A potentiostat controlled the anodic potential, which was fixed in every system at + 0.2 V vs SHE (standard hydrogen electrode). To measure the EASA of every system, cyclic voltammetries (CVs) were carried out at different scan rates. Comparing them with the one obtained with a reference system, each EASA is easily calculated. The nEASA, instead, was measured calculating the geometric volume. The obtained results demonstrate the fundamental role of the EASA and, moreover, the necessity to reduce as much as possible the nEASA in order to enhance the performance. [ABSTRACT FROM AUTHOR]

Chronic wound biofilm infections represent a major clinical challenge which results in a substantial burden to patients and healthcare systems. Treatment with topical antibiotics is oftentimes ineffective as a result of antibiotic‐resistant microorganisms and biofilm‐specific antibiotic tolerance. Use of biocides such as hypochlorous acid (HOCl) has gained increasing attention due to the lack of known resistance mechanisms. An HOCl‐generating electrochemical bandage (e‐bandage) is designed that delivers HOCl continuously at low concentrations targeting infected wound beds in a similar manner to adhesive antimicrobial wound dressings. A battery‐operated wearable potentiostat is developed that controls the e‐bandage electrodes at potentials suitable for HOCl generation. It is demonstrated that e‐bandage treatment is tunable by changing the applied potential. HOCl generation on electrode surfaces is verified using microelectrodes. The developed e‐bandage shows time‐dependent responses against in vitro Acinetobacter baumannii and Staphylococcus aureus biofilms, reducing viable cells to nondetectable levels within 6 and 12 h of treatment, respectively. The developed e‐bandage should be further evaluated as an alternative to topical antibiotics to treat wound biofilm infections. [ABSTRACT FROM AUTHOR]

Objective: According to the American Association of Endodontists (AAE), 22 million endodontic procedures have been performed annually. Root canal treatment is needed to prevent infection and restore function when a tooth is severely infected or decayed. This procedure is the only way to preserve the natural tooth and avoid artificial replacement (implant, denture, etc.). The current study aims to develop an electrochemical reamer (EC-Reamer or EC-R) that can help to disinfect the canal system and thus improve the success rate of root canal treatment. Methods: The COMSOL Multiphysics software was utilized to simulate the experimental setup and confirm the current flow in the electrolyte. The benchtop experimental approach follows a specific electrochemical protocol, (i) open circuit potential to monitor the electrochemical stabilization and (ii) potentiostatic scan at -9.0 V as the treatment stage. Identification of feasible reference electrode (RE) and insulation material for the exploratory benchtop studies considered platinum (Pt) and gold (Au) wire as the REs and hot melt adhesive (HMA) and liquid tape as the insulation materials. The antimicrobial effects of EC-R were analysed using Enterococcus faecalis (E. faecalis). One-way ANOVA with the Tukey post hoc test and a significance level of P<0.05 is used to compare the groups with an experimental duration of 60 seconds. Results: The findings showed that magnitude and current fluctuations created by Pt wire are promising when compared to Au wire, while Pt-HMA pair is chosen considering Pt's good electrochemical inertness and HMA's easy handling, availability, and non-hazardous features. The use of potentiostatic duration of 1 s and 3 s resulted in >99.99% E. faecalis reduction. Duration at 5 s and above resulted in a total bacterial kill. Statistical analysis confirmed a significant difference among the groups tested with commercial and custom-built potentiostats. Conclusion: The outcome provided preliminary data for developing an EC-R prototype to enhance the antimicrobial effect during root canal treatment potentially. [ABSTRACT FROM AUTHOR]

The potentiostat is one of the most important instrument for research in the electrochemistry area. However, access to this kind of equipment may be limited because of the commercial price. In the last decades, many advances have been made towards developing low-cost and open-source versions of potentiostats for engineers and scientists. Furthermore, a lot of effort was put into the improvement of instrumentation and electronics for chemical analysis and, into the development of programming languages in the field of chemistry. However, many chemists have a limited capacity in this area since they are often not exposed to this expertise as part of a core undergraduate/graduate curriculum. This review aims to help and encourage chemists to explore the electronics and computer fields, proposing the use of these tools for research and education. Furthermore, it presents the most useful open-source, low-cost, lab-made potentiostats built to date, assessing their accessibility and electrochemical application capabilities, while providing the necessary information for readers to understand the advancements and limitations of each device. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrochemical measurement methods are widely used to analyze various biochemical reactions due to their simplicity and versatility. Therefore, the development of potentiostats, electrochemical-based analytical instruments, that are low in cost but maintaining rich analytical features is highly demanding. In this paper, we report the development of a low-cost and portable potentiostat system, named ESPotensio, which supports six different electrochemical measurement methods and a multi-channel electrochemical measurement. The measurement methods it supports include the cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV), differential pulse voltammetry (DPV), normal pulse voltammetry (NPV), and the observation of electrochemical response current against time based on chronoamperometry (CA) measurement method. Moreover, each of these measurement methods can be run semi-parallelly within three different channels. The electrochemical measurement precision, accuracy, and error of ESPotensio were evaluated based on the repeated measurements and the comparison with the commercial potentiostats. The results showed that it could produce highly accurate electrochemical measurements by having an average accuracy of more than 90% compared to the commercial potentiostat, Emstat Pico. Ultimately, the hardware design was determined accordingly to meet the low-cost demand by costing of only USD 21.4 for the total system realization.

Glucose meters have been developed for determining the hyperglycemic and hypoglycemic disorders as well as checking daily glucose levels for diabetic patients. Although multiple commercial glucometers have been presented, the attendance of interferences in the measuring of glucose is still a challenge. This problem can be managed using the proper design of potentiostat as the main part of glucometers. Here, we introduce a novel electrochemical circuit design comprising a microcontroller to specify the optimum zero point for the glucose measuring. The proper configuration of the potentiostat circuit leads to the correct detection of zero point for glucose. For this, the counter electrode (CE) is placed in high impedance mode, as well as the working electrode (WE) and reference electrode (RE) in the feedback path of the transimpedance amplifier circuit. The linear range of the proposed sensor was detected in the concentration ranges of 57–600 mg/dL with a linear equation of ${y}={0.0018} {x}-{0.0693}$ and a sensitivity of 0.0018. The final cost and characteristics of our proposed circuit were better than some other devices. [ABSTRACT FROM AUTHOR]

This paper presents a low-noise potentiostat readout circuit with a chopper fully differential difference amplifier (FDDA) for glucose monitoring. Glucose monitoring is necessary for the early diagnosis of diabetes complications and for health management. Ammeter electrochemical sensors are widely used for glucose detection, and in general, a three-electrode structure of a reference electrode (RE), a counter electrode (CE), and a working electrode (WE) is implemented with a potentiostat structure. A low-noise characteristic of the readout circuit is essential for highly accurate glucose monitoring. The chopping technique can reduce low-frequency noises such as 1/f noise and can achieve the required low-noise characteristic. The proposed potentiostat readout circuit is based on a low-noise chopper FDDA with a class-AB output stage. The implementation of the chopper FDDA scheme of the potentiostat readout circuit can decrease the number of amplifiers in the control part of the potentiostat, with reduced power consumption and a wide dynamic output range. The negative feedback loop of the inverting amplifier scheme with the FDDA maintains the voltage between the WE and RE constants. The negative feedback loop tracks the reference voltage of the RE with an input voltage of the WE. The proposed potentiostat readout circuit is designed in the standard 0.18 µm CMOS process, and the simulated current consumption is 48.54 μA with a 1.8 V power supply. The simulated input-referred noise level was 8.53 pArms. [ABSTRACT FROM AUTHOR]

This work studies the feasibility of using a battery-less Near-Field Communication (NFC) potentiostat for the next generation of electrochemical point-of-care sensors. A design based on an NFC microchip, a microcontroller, and a custom potentiostat based on an operational amplifier is presented. A proof-of-concept prototype has been designed and used to quantify glucose concentration using commercial glucose test strips from chronoamperometry measurements. The device is harvested and the sensor is read using a mobile phone. The prototype uses an antenna loop covered with ferrite sheets to ensure stable operation of the electronics when the mobile phone is used as reader. The use of ferrite reduces the detuning caused by the proximity of the metal parts of the mobile phone. A comparison with a commercial glucometer device is provided. Results obtained using a commercial glucometer and those provided by the proposed potentiostat show an excellent agreement. [ABSTRACT FROM AUTHOR]

A handheld USB-powered instrument developed for the electrochemical detection of nucleic acids and biomolecular interactions is presented. The proposed instrument is capable of scanning ± 2.25 V while measuring currents up to ±10 mA, with a minimum current resolution of 6.87 pA. Therefore, it is suitable for nucleic acid sensors, which have high background currents. A low-cost microcontroller with an on-chip 16-bit analog-to-digital converter, 12-bit digital-to-analog converter, and a built-in USB controller were used to miniaturize the system. The offset voltages and gain errors of the analog peripherals were calibrated to obtain a superior performance. Thus, a similar performance to those of the market-leader potentiostats was achieved, but at a fraction of their cost and size. The performance of the application of this proposed architecture was tested successfully and was found to be similar to a leading commercial device through a clinical application in the aspects of the detection of nucleic acids, such as calf thymus ssDNA and dsDNA, and their interactions with a protein (BSA) by using single-use graphite electrodes in combination with the differential pulse voltammetry technique. [ABSTRACT FROM AUTHOR]

This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed.

The Implication and Inhibition Boolean logic gates were realized using NAD+/NADH‐dependent dehydrogenases combined with hexokinase competing for biomolecule input signals. Both logic gates operated with the same enzyme composition and their reconfiguration was achieved simply by redefining the input signals. The output signals produced by the logic gates were analyzed optically and electrochemically, particularly using enzyme‐modified electrodes. The logically processed input signals were used to switch operation of a biofuel cell and activate a molecule release process. [ABSTRACT FROM AUTHOR]

With the rise of zoonotic diseases in recent years, there is an urgent need for improved and more accessible screening and diagnostic methods to mitigate future outbreaks. The recent COVID-19 pandemic revealed an over-reliance on RT-PCR, a slow, costly and lab-based method for diagnostics. To better manage the pandemic, a high-throughput, rapid point-of-care device is needed for early detection and isolation of patients. Electrochemical biosensors offer a promising solution, as they can be used to perform on-site tests without the need for centralized labs, producing high-throughput and accurate measurements compared to rapid test kits. In this work, we detail important considerations for the use of electrochemical biosensors for the detection of respiratory viruses. Methods of enhancing signal outputs via amplification of the analyte, biorecognition of elements and modification of the transducer are also explained. The use of portable potentiostats and microfluidics chambers that create a miniature lab are also discussed in detail as an alternative to centralized laboratory settings. The state-of-the-art usage of portable potentiostats for detection of viruses is also elaborated and categorized according to detection technique: amperometry, voltammetry and electrochemical impedance spectroscopy. In terms of integration with microfluidics, RT-LAMP is identified as the preferred method for DNA amplification virus detection. RT-LAMP methods have shorter turnaround times compared to RT-PCR and do not require thermal cycling. Current applications of RT-LAMP for virus detection are also elaborated upon. [ABSTRACT FROM AUTHOR]

Abstract The most important inhibitors used in bronze disease are BTA and AMT. While these inhibitors control corrosion, they are toxic and cancerous. In this study, the acacia fruit extract (200 ppm to 1800 ppm) was used to the prevention of corrosion inhibition of bronze alloy in corrosive sodium chloride solution 0.5 M, for 4 weeks consecutively. The Bronze alloy used in this research, was made based on the same percentage as the ancient alloys (Cu-10Sn). IE% was used to obtain the inhibitory efficiency percentage and Rp can be calculated from the resistance of polarization. SEM–EDX was used to evaluate the surfaces of alloy as well as inhibitory. The experiment was conducted in split plot design in time based on the RCD in four replications. ANOVA was performed and comparison of means square using Duncan's multiple range test at one percent probability level. The highest rate of corrosion inhibition (93.5%) was obtained at a concentration of 1800 ppm with an increase in the concentration of the extract, corrosion inhibition also increased, i.e., more bronze was prevented from burning. Also, the highest corrosion inhibitory activity of Acacia extract (79.66) was in the second week and with increasing duration, this effect has decreased. EDX analysis of the control sample matrix showed that the amount of chlorine was 8.47%wt, while in the presence of corrosive sodium chloride solution, after 4 weeks, the amount of chlorine detected was 3.20%wt. According to the morphology (needle and rhombus) of these corrosion products based on the SEM images, it can be said, they are the type of atacamite and paratacamite. They have caused bronze disease in historical bronze works. The green inhibitor of Acacia fruit aqueous extract can play an effective role in inhibiting corrosion of bronze, but at higher concentrations, it became fungal, which can reduce the role of Acacia fruit aqueous extract and even ineffective. To get better performance of green inhibitors, more tests need to be done to improve and optimize.

• Octahedral Au@Cu-C bimetallic composite derived from Cu-MOF was synthesized. • An electrochemical aptasensor was constructed by Au@Cu-C alloy and MB as indicator. • The proposed aptasensor realized the detection of homocysteine in the human serum. • The detection was conducted by portable potentiostat, enabling on-site application. Homocysteine (Hcy), a metabolic intermediate of methionine, is a biomarker for neurological, cardiovascular and cerebrovascular diseases. Timely measurement of Hcy acts as a significant role in disease prevention and diagnosis. Given the fast response of the electrochemical sensing method, herein, a sensitive electrochemical aptasensor was proposed for the detection of Hcy. The aptasensor was constructed by utilizing the MOF-derived bimetallic carbon nanocomposites (Au@Cu-C) plus multi-walled carbon nanotubes (MWCNTs) as electrode modification materials and methylene blue (MB) as the signal marker. The Au@Cu-C was synthesized through hydrothermal methods, calcination and simple galvanic replacement reactions. The prepared Au@Cu-C enhance the electrical signal due to the synergistic effect of bimetallic alloy, while the specific morphology facilitated the immobilization of the aptamer. MB, served as the signal marker, can reflect the current changes of the aptasensor caused by the conformational change of aptamer before and after binding Hcy. As a result, the constructed electrochemical aptasensor exhibited a high sensitivity of 0.415 μA μM−1, a low detection limit of 0.017 μM and an excellent recovery rate in the detection of human serum samples. Besides, the detection was performed on the portable potentiostat which demonstrated the potential application of the aptasensor in medical diagnosis and on-site analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

The transition of electrochemical sensors from lab-based measurements to real-time analysis requires special attention to different aspects in addition to the classical development of new sensing materials. Several critical challenges need to be addressed including a reproducible fabrication procedure, stability, lifetime, and development of cost-effective sensor electronics. In this paper, we address these aspects exemplarily for a nitrite sensor. An electrochemical sensor has been developed using one-step electrodeposited (Ed) gold nanoparticles (EdAu) for the detection of nitrite in water, which shows a low limit of detection of 0.38 µM and excellent analytical capabilities in groundwater. Experimental investigations with 10 realized sensors show a very high reproducibility enabling mass production. A comprehensive investigation of the sensor drift by calendar and cyclic aging was carried out for 160 cycles to assess the stability of the electrodes. Electrochemical impedance spectroscopy (EIS) shows significant changes with increasing aging inferring the deterioration of the electrode surface. To enable on-site measurements outside the laboratory, a compact and cost-effective wireless potentiostat combining cyclic and square wave voltammetry, and EIS capabilities has been designed and validated. The implemented methodology in this study builds a basis for the development of further on-site distributed electrochemical sensor networks.

The potentiostat is critical in the development of electrochemical systems; however, its cumbersome detection and high cost considerably limit its large-scale application. To provide an affordable alternative to developing countries and resource-constrained areas, this study designs an electrochemical detection system based on smartphones, which uses Bluetooth Low Energy to convert open-source potentiostat data based on PSoC-5LP. The WeChat application on the smartphone provides an interface for entering experimental parameters and visualizing the results in real time. The smartphone-based electrochemical detection system has a simple design and reduces the size (10×3×0.3 cm3) and the cost of the hardware ($ 18). The system performs the most commonly used cyclic voltammetry for electrochemical detection, with results that are comparable to those obtained using a commercial potentiostat and an error rate of 1.3 %. In the classical teaching experiment of electrochemical determination of ascorbic acid in orange juice samples, the measured value of the system is 0.367±0.012 mg/mL, compared with the standard reference value of 0.37 mg/mL, which is obviously a convincing value. Therefore, this system is a low-cost, reliable alternative to a potentiostat for research, education or product integration development. [ABSTRACT FROM AUTHOR]