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Li-ion batteries that incorporate manganese present several advantages, including low cost and low toxicity. However, these batteries often suffer from dissolution of manganese into the electrolyte solution, severely impeding battery performance. This work describes the quantitative detection of Mn2+ ions in battery relevant environment i.e. non-aqueous electrolyte within an inert atmosphere. To this end, an electrochemical probe was fabricated using electrochemical deposition of a Hg cap onto a 25 μm Pt disk microelectrode. The Pt/Hg microelectrode was fully characterized by optical microscopy, cyclic voltammetry, scanning electrochemical microscopy. Using square wave anodic stripping voltammetry to overcome reproducibility issues with classical linear sweep anodic stripping voltammetry, Mn2+ was quantified in non-aqueous solution with a limit of detection of 14 μM. Finally, using this detection scheme, the trapping ability of aza-15-crown-5 ether and dilithium iminodiacetate was investigated. [ABSTRACT FROM AUTHOR]

D-serine has been implicated as a brain messenger with central roles in neural signaling and plasticity. Disrupted levels of D-serine in the brain have been associated with neurological disorders, including schizophrenia, depression and Alzheimer's disease. Electrochemical biosensors are attractive tools for measuring real-time in vivo D-serine concentration changes. Current biosensors suffer from relatively large sizes (~25 µm) making localized cellular measurements challenging, especially for single cell studies. In this work, a robust methodology for the fabrication of a reproducible miniaturized 10 µm D-serine detecting amperometric biosensor was developed. The miniature biosensor incorporated yeast D-amino acid oxidase immobilized on a poly-metaphenylenediamine modified 10 µm Pt disk microelectrode. The biosensor offered a limit of detection of 0.361 µM (RSD < 10%) with high sensitivity (283 µA cm-2 mM-1, R² = 0.983). The biosensor was stable for over four hours of continuous use, demonstrated a storage stability of four days and high analyte selectivity. Biosensor selectivity was validated with LC-MS and interferences with yeast D-amino acid oxidase were evaluated using drugs believed to stimulate D-serine release. Ex vivo D-serine measurements were made from Xenopus laevis tadpole brains, demonstrating the utility of the biosensors for measurements on living tissue. We observed that D-serine levels in the brain fluctuate with sensory experience. The biosensors were also used in vivo successfully. Taken together, this study addresses factors for successful and reproducible miniature biosensor fabrication for measuring D-serine in biological samples, for pharmacological evaluation, and for designing point of care devices. [ABSTRACT FROM AUTHOR]

Advancements in microelectrode fabrication, instrumentation, and theory have made data collection for scanning electrochemical microscopy (SECM) more accessible than ever before. In contrast, data treatment and analysis is still mostly done using proprietary or in-house tools or scripts. In this work, an open-source, free, Python-based software called Flux has been developed to treat SECM images, approach curves, cyclic voltammograms, and chronoamperograms. Flux provides a user-customizable data workflow that supports a range of common analyses including normalization of currents based on theoretical or experimental steady state currents, calculation of geometric (Rg), thermodynamic (formal potential), or kinetic (heterogeneous rate constant) parameters, and customizable plot formatting. Flux is compatible with standard output files from Biologic, CH Instruments, HEKA, and Sensolytics manufacturers. [ABSTRACT FROM AUTHOR]

While investigating the influence of an alloying element on the corrosion properties of a metal, materials scientists and engineers typically fabricate an array of samples with increasing concentrations of the alloying element in order to build up a gradient of substrates suitable for corrosion testing. The resulting series of substrates can consist of many samples, which can be time consuming to test and hence slow to reveal the effects of the alloying element's concentration. In this work, we present a fast, simple, and reliable methodology on an ideal model system for monitoring the effect of one of the most commonly used alloying elements in Magnesium alloys, aluminum, on magnesium's corrosion behavior using a single Mg-Al diffusion couple sample and the scanning micropipette contact method. The use of ethylene glycol as the solvent was carried out to enhance the stability of the micro electrochemical setup. The corrosion potentials and currents of pure Mg and Al as well as the intermetallic regions were collected using micro polarization measurements without the influence of grain boundaries and inclusion size. Similar measurements performed across the interfacial region of Al diffusion intoMg revealed a threshold value of Al wt% on the corrosion potentials measured. Such methodology proved to be reproducible and therefore is a good way to measure the effects of various alloying elements for any metal in question. [ABSTRACT FROM AUTHOR]

Microelectrodes are small scale electrodes used for electroanalytical detection which have found applications in a wide variety of research areas including biology, kinetics, instrumental development, and surface modification. In this review, we provide a summary of the theory and experimental parameters used for bioelectrochemistry applications of microelectrodes. We then delve into a review of select bio-analytical applications of microelectrodes from 2013 to 2018 and provide a discussion on future research directions. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbenes (NHCs) have been the focus of renewed interest in recent years for their ability to form extremely stable monolayers on noble metals. However, their ability to bond to non-noble metals is less understood. Magnesium is among the most notorious of these, as the native oxide layer is too porous to be passive but too protective to be catalytic. Through X-ray photoelectron spectroscopy (XPS) and potentiodynamic polarization curves (PDP), we find that NHCs with a wide group of side group functionalities increase the electrochemical activity of magnesium, potentially improving its potential for hydrogen storage. [ABSTRACT FROM AUTHOR]

The field of enzymatic biosensors applied to brain electrochemistry has rapidly expanded over the last few years, thanks in part to their excellent selectivity to specific target species. Much current research is therefore focused on enhancing the electrochemical signal, which often involves the detection of stoichiometric amounts of H2O2 formed as part of the enzyme mechanism. This opens the possibility of enhancing a biosensor's performance by facilitating the H2O2 oxidation signal through surface modification. Here, we investigate the impact of the roughness of the platinum surface on the biosensor response, where rougher platinum surfaces show greater activity for H2O2 oxidation, and therefore enhanced biosensor sensitivity. Through careful manipulation of the electrode surface roughness, we are able to show a significant improvement to the LOD when using a rougher electrode surface. Additionally, we have shown that this enhanced surface roughness has no detrimental effects toward the electrode response time. This suggests that surface roughness could be a simple and easy to implement means of enhancing the sensitivity of electrode-based enzymatic biosensors, and is an important factor to consider when studying other aspects of biosensor fabrication. [ABSTRACT FROM AUTHOR]

A new type of an electrochemical flow cell designed for exchangeable ultramicroelectrodes (UMEs) is presented. The cell could be used with up to 8 different UMEs allowing one to use this cell for UME array measurements. The cell was characterized using both empirical data and finite element modeling. Au and Pt UMEs were used to detect catechol simultaneously, demonstrating the ability of this cell to be used as a sensory platform. The electroanalytical response of flow system was validated by direct measurements of H2O2 concentrations. Finally, stochastic nanoparticle measurements were successfully performed using the flow system, highlighting the future possibilities of this system for environmental monitoring. [ABSTRACT FROM AUTHOR]

When studying magnesium alloy corrosion, the quantitative analysis of probe approach curves acquired in the feedback mode of scanning electrochemical microscopy is particularly challenging. The oxidation current of the ferrocenemethanol mediator recorded at conventional Pt microelectrodes is systematically plagued by parasitic faradaic contribution from the oxidation hydrogen. Herein we demonstrate the use of carbon microelectrodes to remove this unwanted faradaic contribution, allowing for in situ time lapse monitoring of the corrosion product layer growth. Applying a one-dimensional diffusion approximation, the extracted rate constants obtained by scanning electrochemical microscopy probe approach curves could be correlated to the corrosion product film thickness and porosity obtained by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Herein we report the characterization of localized corrosion of AZ31B magnesium alloy electrochemically coated with poly(3,4- ethylenedioxythiophene) (PEDOT) from ionic liquid electrolyte. Several scanning probe techniques including high resolution electron microscopy, SVET, SECM amperometric detection of H2 fluxes, potentiometric SECM detection of local pH and localized potentiodyanmic measurements were used to evaluate the microstructure of the coating and its corrosion protectiveness. In order to examine long-term durability of corrosion protection due to the PEDOT coating, these measurements were performed after different immersion times. It was observed that PEDOT coating appears to lose its protective ability after localized coverage of corrosion products. The results of this study provide important information considering the interest in this coating for se in biomedical implants and prior indications of beneficial passivation. [ABSTRACT FROM AUTHOR]

Successful in situ spatiotemporal tracking of corrosion processes occurring at heterogeneous Mg alloy microstructures was achieved through tandem analyses involving electron and electrochemical microscopies. Through cross-correlation of scanning electron microscopy and scanning electrochemical microscopy images and subsequent analytical transmission electron microscopy, the morphology and chemical composition of microstructural components on the surface of a sand-cast AM50 Mg alloy were related to their respective local evolution of H2 with micron scale resolution prior to, during and post corrosion. The results confirm that the preferential water reduction sites in the initial stages of corrosion are the AlgMns intermetallics while a β-Mg17Al12 precipitate contaminated with Ni becomes cathodically active at a later stage of corrosion. This approach demonstrates the power of correlative approaches to probe and understand local electrochemical phenomena. [ABSTRACT FROM AUTHOR]

The article focuses on the Journal of The Electrochemical Society that focused on organic and inorganic molecular electrochemistry.

The introduction of the periodical is presented with in the issue Brain and Electrochemistry.