bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust Design of Silicon/Graphite Composite Via Atomic-Scale Rearrangement for High Performance Lithium Ion Batteries
Authors: Lee Taeyong , Cho Jaephil
Published: February 2020

State-of-the-art lithium-ion battery (LIB) technology are still challenged with many other requirements, including high-energy density, long cycle life, safety and cost by the increasing demand of the electric vehicle energy-storage market. Moreover, key to success for commercialization of EVs is reducing the charging time of the batteries. In general, the conventional graphite has shown not only low electrochemical performance but also safety problems arisen from the metallic lithium plating at the surface of the anode electrode at the high current density (4mA/cm2) due to a sluggish kinetics during intercalation reaction and working voltage potential neighboring almost 0V (versus Li/Li+). Alternatively, among the alloy-type anodes, silicon is considered as promising anode material due to the high gravimetric capacity of 3572 mAh g-1 and proper lithium-alloying potential (0.22 V vs. Li/Li+) to prevent unwanted lithium plating. However, to the best of our knowledge, the majority of previously reported Si anodes do not demonstrate the rate capabilities at high electrode density (g/cc) due to the large volume changes (>300%) and low electrical conductivity of Si anodes.

Herein, we have proposed a composite consisting of a nanoscale silicon coating layer on graphite/carbon nanofibers through nickel-catalyzed-CNF growth on the graphite by chemical vapor decomposition (CVD) using both ethylene (C2H4) and silane (SiH4) gas. The chemical Si-C bonding by atomic rearrangement of CNF and a-Si layer prevents the exfoliation of the active Si layer from the surface of CNF during cycles. For practical viability, all electrochemical tests were performed in the full-cell as well as in the half-cell configurations with high energy density (> 1.6g cc-1), high areal capacity (3.3 mAh cm2) and limited binder composition (< 4wt %). As a result, by increasing electrical conductivity of silicon/graphite composite and existing high stability of ultrathin Si layer, our composite shows remarkable improvement in electrochemical performances even at high current density with those of the conventional graphite.
Chemically Synthesised ϒ-MnO2, and β-MnO2/Single Wall Carbon Nanotube Composites As a Promising High Capacity Cathode Materials for Lithium-Ion Batteries
Authors: Ahmed Zahoor , Cameron Hayden , Donne Scott W
Published: February 2020

This work reports the ϒ-MnO2, and β-MnO2 single wall carbon nanotube (SWCNT) nanocomposite cathode material synthesised successfully by chemical method for lithium-ion batteries. The electrochemical properties galvanostatic charge-discharge, cycle ability, rate performance and cyclic voltammetry were greatly enhanced by using the (SWCNT) composite cathode as a comparison to the pristine ϒ-MnO2, and β-MnO2. As a consequence, the modified (SWCNT) composite cathode material exhibits superior initial discharge capacity 255 mAh g-1 at 0.1C with coulombic efficiency of 99.22% and 118 mAh g-1 at 1C with a capacity retention (coulombic efficiency) of 95.5% (99.9%) after 100 cycles in the potential window of 2.0-4.5V (vs Li/Li+). In comparison pristine β-MnO2 exhibit only 169 mAh g-1 at 0.1C, corresponding to lower initial coulombic efficiency of 97% and 73 mAh g-1 at 1C with capacity retention (coulombic efficiency) of 71.4% (92%) after 100 cycles. The significant improvement in the de-/lithiation kinetic can be accredited to the enhancement in apparent lithium ion diffusion coefficient and electronic conductivity making it more applicable in high power commercialization.
(Invited) Ni-Rich and Low-Co Cathode Materials for Advanced Lithium Ion Batteries
Authors: Xiao Jie
Published: February 2020

Ni-rich and low-Co cathode materials in the family of Li[NixMnyCoz]O2 (x+y+z=1) have been intensively studied in recent years because of their high capacity to boost the cell energy for next-generation Li-ion batteries. The majority of MMC cathodes are synthesized as polycrystalline by using traditional co-precipitation methods which produce agglomerated secondary particles consisting of nano-sized primary particles. The porous structure of secondary particles benefits the electrode wetting and shortens ion diffusion especially at high rates, although particle cracking along grain boundaries is seen upon cycling. Further increasing Ni content in NMC increases the cathode capacity to be above 200 mAh/g. However, the content of active Ni3+ and oxygen species also increase cocurrently, which leads to gas generation and moisture sensitivity issues, plaguing the large-scale adaption of Ni-rich cathode by industry. Single crystalline Ni-rich cathode with reduced surface areas is thereby proposed in this work to substantially reduce the active sites available for moisture attack and side reactions with electrolyte. More importantly, at electrode level, single particle Ni-rich cathode benefits the dense packing of electrodes without sacrificing reversible electrochemical capacity and energy. The tortuosity of thick electrodes is also reduced enhancing the cell-level performances of thick cathodes. This talk will discuss the fundamental relationship among synthesis-structure-performance in Ni-rich and low-Co cathode at relevant scales.
Designing High Power Lithium Ion Cells
Authors: Lain Michael J. , Brandon James , Kendrick Emma
Published: February 2020

Applications like hybrid electric vehicles (HEV) require batteries with high volumetric and gravimetric power densities, in both charge and discharge modes. Lithium ion cells are now being designed with different power : energy ratios, for specific applications. Many cells are rated for high rate discharge (> 10 C), but not for high rate charge (< 2 C). However, even 10 C is not enough.

A selection of commercial lithium ion cells, mainly cylindrical 18650 cells, were disassembled and characterised. The cells had a variety of different power : energy ratios, and this was correlated with key design parameters. For example, cells with a high power density had relatively low coat weights and areal capacities, and used active materials with a smaller particle size. However, most of the cells had the same tag arrangement, when high power cells were predicted to use more tags.

Having disassembled the cells, the harvested electrodes were tested in coin cell half cells. The tests included resistance measurements, continuous discharge tests at relatively low rates, and pulse charge and discharge tests at high rates. During lithiation pulses, all the anode voltages went negative of zero volts vs. Li/Li+ by around 5 C. However, the reaction still appeared to be under solid state diffusion control, based on the linearity of the voltage vs. time0.5 GITT plots.

These and other results will be presented at the meeting.
(Invited) Understanding Interfacial Reactivity in Li-Ion Battery Cathodes and the Effect of Surface Modifications
Authors: Cabana Jordi
Published: February 2020

Reactivity at interfaces between Li-ion battery cathodes and electrolytes imposes limitations to activity and durability. Before solutions can be devised, it is indispensable to precisely define the underlying chemical mechanisms. Interfacial instability is driven by the formation of highly oxidized species on the surface of the cathode particles, but these mechanisms are inherently local and they depend on their morphology and chemistry. A combination of X-ray absorption spectroscopy and X-ray microscopy will be presented to establish the changes undergone by cathode particles at different points of the charge, revealing the consequences of interfacial reactions at very high spatial resolution.

Modifying the surface of the cathode particles with redox-inactive cations is an established strategy to prevent these undesired reactions and increase electrode durability generally. Developments will be discussed in the manipulation of chemical assembly to achieve the highest level of sophistication in this approach, through core-(epitaxial) shell architectures at the level of primary particles. The nanostructures are produced via colloidal methods that generate objects with high chemical and morphological definition. As a consequence, they constitute valuable models to evaluate effect of surface modifications on cathode-electrolyte interfacial interactions. The presentation will establish comparisons of the changes at the surface of cathode particles depending on the presence and identity of a passivating shell. These comparisons inform the definition of mechanisms of stabilization, which will be subsequently used to propose further avenues of design towards cathodes with high capability for energy storage with long life.
Unraveling the Rapid Redox Reactions through Superstructure of Lithium-Excess Layered Oxides
Authors: Jin Wooyoung , Cho Jaephil
Published: February 2020

Lithium-excess layered oxides (LLOs, Li1+xNiyCozMn1-x-y-zO2, > 250 mAh g-1) have lower rate capability than conventional layered oxides, which is one of the major problems to be solved for these materials. Such phenomena are attributed to the unfavorable electrochemical reactions such as sluggish kinetics and large voltage hysteresis caused by cationic/anionic redox reaction. To enhance the rate capability of LLOs, understanding the cationic/anionic redox reaction with respect to C-rate is needed. Here, we compare the electrochemical properties at low C-rate and high C-rate of two different superstructure, specifically the local structure of Li/TM ordering (Li1.15Mn0.51Co0.17Ni0.17O2 (Li/TM ordered arrangement) and Li1.09Mn0.55Ni0.32Co0.04O2 (Li/TM disordered arrangement)). Through in-situ quick-scanning X-ray Absorption Spectroscopy, we reveal that local atomic configuration affects the competitive reaction of cationic/anionic redox, leading to a difference in structural reversibility and electrochemical reversibility. Our study provides insight into the reversibility at high C-rate in anion redox cathode materials and helps to develop the fast charging/discharging cathode materials.
Structural Distribution of Redox-Active Oxygen Governing Chemical Reversibility in Li- and Mn-Rich Layered Oxides
Authors: Hwang Jaeseong , Cho Jaephil
Published: February 2020

Li- and Mn-rich layered oxides (LMR) come into the spotlight due to anomalously high capacities under O redox. However, O redox also incurs undesirable situations: voltage fade, inhomogeneous kinetics and low coulombic efficiency, limiting a practical use. Herein, through a comparative study on LMR (Li1.15Mn0.51Co0.17Ni0.17O2) having different distributions of redox-active oxygen in a structural arrangement, we reveal the origin of irreversible properties of LMR, which appear mainly at low voltage redox region (LVRR, ~3.0V). Focusing on chemical reversibility at LVRR, real-time simultaneous observations on competitive TM-O redox behavior and TM occupancies in Li sites were conducted using operando fine-interval X-ray absorption spectroscopies. First-principles calculations demonstrate that the dispersed arrangement of redox-active oxygen stabilizes TM-O coordination, leading to restrained TM migration and reversible O redox. The enlightenment of chemical reversibility which considers the real-time changes in electronic/crystalline structures provides a new perspective on a structural design for ideal future LMR.
Improvements to Disordered Rock-Salt Li-Excess Cathode Materials
Authors: Yi Tanghong , Carroll Kyler J. , Strand Dee , Li Bin
Published: February 2020

Cathode materials with higher energy density than layered oxide materials are required for future demands of vehicle electrification. Disordered rock-salt Li-excess structures, such as Li3NbO4, have been demonstrated to achieve capacities of greater than 300 mAh/g reversible capacities at elevated temperatures. The high capacity is believed to be due to reversible redox chemistry of the oxide anions. This new class of high energy cathode materials provides an opportunity for a step change increase in cell level energy density. However, improvements are still required in material conductivity and stability. In this presentation, we demonstrate material improvements which enable high specific capacity at room temperature and extended cycle life.
Lithium/Oxygen Incorporation-Induced Structural Transformation during Synthesis of Cobalt-Free Li-Mn-Rich Oxides
Authors: Hua Weibo , Schwarz Björn , Knapp Michael , Etter Martin , Schökel Alexander , Binder Joachim R. , Indris Sylvio , Ehrenberg Helmut
Published: February 2020

Cobalt-free Li-Mn-rich layered oxides (LMLOs) are regarded as promising cathode materials for advanced lithium ion batteries (LIBs) because of their high discharge specific capacities (> 250 mAh g-1). However, the formation mechanism during the synthesis of these oxides has not been fully understood, i.e. how are lithium and oxygen incorporated into the matrix architecture of the Li-free precursor on the process of high-temperature solid-state reaction? Herein, in situ high-temperature synchrotron radiation diffraction experiments were performed to monitor the structural evolution of the precursor combined with lithium source during thermal treatment. The in situ high-temperature diffraction results show that, with an increase in heating temperature, lithium and oxygen continuously enter into the spinel host matrix (Fd-3m) formed from the Li-free precursor, thus gradually causing the production of a halite-type phase (Fm-3m) and eventually results in the formation of a monoclinic layered phase (C2/m). These findings not only provides valuable information for industrial operation, but also contributes to a deeper understanding of the correlation between the synthesis, structure and electrochemical performances in LMLOs.
Improvement of Specific Capacitance in Lithium Ion Batteries By Mesoporous Carbon Hybrid Nanostructures
Authors: Dorvilien Valerio , Rojas Carolina Valeria , Santa Cruz Neida , Mendoza Frank , Weiner Brad R. , Morell Gerardo
Published: February 2020

We propose a low cost and simple method to prepare carbon hybrid structure-based electrodes in this study. Hybrid-structure Carbon Nanostrures was obtained using a zeolite as a template. The resulting carbon nanostructure is mostly configured by Graphene and multiwall carbon nanotubes (G/MWCNTs). The G/MWCNTs were dispersed onto the shallow surface of alumina foil forming as the electrodes. The electrical conductivity and dispersed morphology of the G/MWCNTs -based conductive electrode were examined by atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Using the standard method we assembled the Lithium Ion Battery in the Ar-filled glove box, we used LiPF6 with EC:DMC::1:2 ratio as the electrolyte, lithium foil as the counter electrode and G/MWCNTs material. The specific capacity and cycle-life stability of the G/MWCNTs-based lithium ion battery was investigated by cyclic voltammetry analysis.
Investigation of Novel Electrolyte Formulations for Li4Ti5O12/LiMn2O4 Cells
Authors: Lucht Brett , Kim Jongjung , Payne Martin , Hoffmann Jennifer , Milien Mickdy
Published: February 2020

Lithium titanate (LTO) has been investigated as one of the leading anode materials for lithium ion batteries in grid storage and automotive applications. However, one of the primary challenges is cell gassing which can significantly limit life of cells despite the excellent lifetime performance of LTO anodes. Gas evolution has been previously attributed to water impurities from the electrolyte, moisture trapped in the electrode, the breakdown of lithium salt forming hydrofluoric acid (HF), and/or solvent reactions with the surface of the electrode. The role of electrolyte formulation with and with additives in performance of Li4Ti5O12/LiMn2O4 cells has been investigated. ATR-IR and X-ray photoelectron spectroscopy has been used to gain an understanding of the surface films formed with different additives while in-situ gas measurements based on Archimedes’ principle and gas chromatography have given insight into how the implementation of these additives affects gassing. The results from this study enable the selective design of surface films for LTO anodes, which reduces gassing at elevated temperatures without sacrificing performance.
Thin Film Lithium Niobites with Intrinsic High-Rate Performance for Lithium-Ion Batteries
Authors: Lee Dong-Chan , Shank Joshua C. , Doolittle W. Alan , Alamgir Faisal M.
Published: February 2020

Lithium-ion batteries have been broadly favored as one of the best energy storage systems which have various classes of electrode materials being studied to satisfy the demand on improved electrochemical performance. As a similar class to titanium-based oxides, niobium-based oxides continue to be considered as promising electrode materials with multiple pairs of Nb redox couples, which can deliver more capacity than Ti-based oxides depending on their phase and charge/discharge condition. Among several phases of niobium oxides, lithium niobite (LiNbO2) has attracted scientific attention as a mixed ion-electron conductor proposing its use for the optical application as well as memristor and superconductor. Nevertheless, the research on lithium niobites still lacks, especially for the use as energy storage materials in lithium-ion batteries.

By sputter deposition, 1.1-micron-thick lithium niobite membranes were fabricated for thin film electrodes. The characterization using XRD and XPS with consecutive etching confirmed the unique (101)-oriented crystalline arrangement of as-synthesized thin film electrodes and elucidated their initial lithium deficiency. Free of conducting agent and binder, the electrodes exhibited high capacity utilization and stable retention over 400 cycles. They also presented remarkable high-rate performance even at 14 A/g of extremely high current density (ca. 70C) and demonstrated a full recovery of capacity at the subsequent moderate rate. It was revealed the unit parameter change originated from the insertion and desertion of lithium cations occupying the octahedral sites between (NbO2)n- layers of edge-shared NbO6 trigonal prisms. None of phase evolution or extinction during the cycling implies that the major capacity contribution of lithium niobite comes from the single-phase intercalation reactions, which was supported by voltage profiles as well. Post-mortem analysis using XPS with Ar ion etching enabled to suggest that besides the main intercalation reaction, from Li0.5NbO2 to LiNbO2, about 9.3% of LiNbO2 undergoes a conversion reaction to Nb.
Role of Oxygen Vacancy Defects in the Electrochemical Performance of Substoichiometric Molybdenum Oxide
Authors: Cui Yanhua , Wei Kaiyuan , Zhao Yu , Zeng Chao , Cui Yixiu
Published: February 2020

MoO3-x thin films have been prepared by pulsed laser deposition (PLD). The oxygen-vacancies could not only greatly increase the interlayer spacing and the electrical conductivity of MoO3, but also significantly enhance the electrochemical activity, which leads faster charge storage kinetics. The oxygen vacancies have been characterized using a series of techniques: X-ray absorption fine structure, X-ray absorption near edge structure. Through a combination of density functional theory and experiments, the role of the oxygen vacancy sites in the redox reaction activity of MoO3-x is identified. The MoO3-x thin film exhibited good reversibility. And the reversible discharge capacity of above 520 mA h g-1 was achieved after 100 cycles. In further data analysis, the differences between the compositions are investigated, the concentration of oxygen vacancies is estimated, and the possible effects on the cation defect chemistry and phase formation of MoO3-x are discussed. The reaction mechanism of MoO3-x thin-film electrode has been investigated by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. These results confirmed that incorporating oxygen vacancies into transition metal oxidesiis is an effective strategy for increasing the material's electrochemical reactivity.

Figure 1
(Invited) Molecular Scale Modeling of Structure, Transport and Electrochemistry of Aqueous and Non-Aqueous Electrolytes
Authors: Borodin Oleg , Pollard Travis P , Vatamanu Jenel
Published: February 2020

A molecular scale insight into ion transport and decomposition is important for understanding deficiencies of the currently used aqueous and non-aqueous electrolytes. In this presentation I will summarize progress made towards improving molecular scale understanding of the structure and electrochemistry for a wide range of aqueous and non-aqueous electrolytes. Because no one simulation technique is capable of efficiently capturing all transport and electrochemical properties at interfaces, we will utilize a combination of multiple modeling methods: a) density functional theory (DFT) studies of the solvent reactions on cathode surfaces and at the solid electrolyte interphase (SEI) covering lithium metal; b) representative quantum chemistry (QC) calculations performed on the representative small model electrolyte clusters to estimate oxidation and reduction; c) molecular dynamics (MD) using APPLE&P polarizable force field to examine bulk and interfacial properties of electrolytes and electrochemical interfaces; d) new generation of the force fields for accurately capturing electrolyte transport properties and transference number. Combined together information from these modeling scales suggests numerous strategies for stabilizing the electrolyte – electrode interfaces for numerous aggressive high energy density cathodes combined coupled with graphite and metal anodes.
The Interplay of Electrode Heterogeneity, SEI Growth, and Li Plating in Li-Ion Batteries
Authors: Pouraghajan Fezzeh , Sun Fei , Mazzeo Brian , Wheeler Dean
Published: February 2020

Newman-type or macrohomogeneous cell models have had a significant contribution toward designing and optimizing Li-ion batteries. In order to lower the computational cost and accommodate limited experimental information, this model assumes that battery electrodes are functionally homogenous. However, this assumption can be far from reality even for commercial-quality electrodes, due to variability in microstructure that arises during the manufacturing process.

Previous work in our group showed that electrode heterogeneity can lead to non-uniform distribution of current density, positive and negative electrode states of charge, and charge/discharge capacities [1]. Consequently, heterogeneity can cause faster degradation of materials, prevent maximum utilization of active materials, and even lead to catastrophic failure of the cell.

Among the different modes of cell aging, solid electrolyte interphase (SEI) growth and Li plating are considered mainly responsible for capacity fade due to loss of active Li. In this study, we will discuss how electrode heterogeneity can lead to non-uniform SEI growth and Li plating, and how the growth of this resistant layer affects the level of heterogeneity, performance, and lifetime of the cell.

To better understand the interplay of the electrode’s heterogeneity and cell aging, we use a combination of a Newman-type model and an equivalent-circuit model for an NMC cathode and graphite anode. The equivalent-circuit model consists of three parallel resistances, each represent high, medium, and low conductivity regions in an electrode film.

This research was funded by the BMR program of the US Department of Energy.

[1] Forouzan et al., J. Electrochem. Soc. 165, A2127-A2144 (2018).
Point-of-Care Electrochemical Detection of Sulf Marker Activity for Lung Cancer Diagnosis in Human Body Fluids
Authors: Wang Zhe
Published: February 2020

Sulf, as the 6-O endosulfatase of heparan sulfate proteoglycans (HSPGs), has been reported in many previous works that it plays the significent role in the pathogenesis of a variety of human cancers. Here we proposed that instead of concentration, the actived Sulf will be more critical in this process. However, there are very few reports about point-of-care method to evaluate sulf 1 activity currently. In this work, an electrochemical method using HSPGs as a substrate was employed to detect the concentration of sulf 1. HSPGs, a glycoprotein with the common characteristic of containing one or more covalently attached heparan sulfate (HS) chains, is a type of glycosaminogly can mediate the activation of a variety of cell growth factor signal pathway to promote the progression of cancers. The disaccharide units of HS chains have four different sulfation modification sites, which are substituted on the N-, 3-O, and 6-O positions of glucosamine and the 2-O position of uronic acid residues. Considering sulf 1 can transform the 6-O sulfation of HSPGs to OH group, as shown in figure 1, the structure and electrical property of HSPGs could take some changes. Here, electrochemical impedance spectroscopy (EIS) was used to detect the changes of electrical property of HSPGs before and after reacting with sulf standard solution. Through analyzing and calculating the electrical parameters obtained by EIS, such as charge, capacity and degree of phase, we established the calibration curve of sulf concentration, which could be further used to detect the sulf concentration of human blood samples. This work offers a new method for sulf detection and has great potential in the early detection of lung cancers.
Development of Flexible Electrochemical Glucose Sensors By Inkjet Printing of Novel Graphene Surfaces
Authors: Uzunoglu Aytekin
Published: February 2020

Flexible electrodes have been widely employed in wide range of applications including flexible electronics and sensors, bendable screens, and energy storage and conversion devices (1, 2). The wide range application of these materials made it essential to develop novel flexible electrodes with low cost, high performance and durability. In the present work, we aimed to develop novel inks formulations to be used in inkjet printing method to fabricate flexible electrodes. For this purpose, we modified the surface of graphene layers with sulfonate (-SO3H) groups to achieve more stable ink formulations with higher graphene contents than 0.1 mg/ml which is widely used in the literature (3). The catalytic activity of SO3H-modified graphene was improved significantly by decorating the surface with Pd nanoparticles. Thereafter, the prepared ink formulations were deposited on flexible PET substrate using an inkjet printing method. The surfaces of the fabricated electrodes were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM) methods. In addition, the electronic properties of the electrodes were determined using 4-probe method as a function of repeated printing steps. After the physical and chemical characterizations, the flexible electrodes were used as electrochemical sensors for the detection of glucose. Our preliminary results indicated that the modification of graphene surface with -SO3H and Pd enabled to develop flexible electrochemical glucose sensors with high performance.

References:

R. P. Tortorich, J. W. Choi, Inkjet Printing of Carbon Nanotubes. Nanomaterials
3, 453-468 (2013).

E. B. Secor, P. L. Prabhumirashi, K. Puntambekar, M. L. Geier, M. C. Hersam, Inkjet Printing of High Conductivity, Flexible Graphene Patterns. Journal of Physical Chemistry Letters
4, 1347-1351 (2013).

S. K. Eshkalak et al., A review on inkjet printing of CNT composites for smart applications. Applied Materials Today
9, 372-386 (2017).
Development of Physical Property Measuring Device for 3D Food Printer Gel
Authors: Ishigaki Ryo , Kawakami Masaru , Furukawa Hidemitsu
Published: February 2020

In recent years, research and development of 3D food printers have been actively conducted, and it is expected to change the future food problems immensely and the way of food manufacturing and processing.

In the Food Layer Manufacturing(FLM) 3D food printer, the molding conditions must be set for physical properties of the each material. In the previous study, researches were conducted on the relationship between viscosity and molding conditions by rheometer or viscometer, and it is reported that the modeling accuracy improves as viscosity increases. However, since it is difficult to use a rheometer or a viscometer at each household, a simple physical property measuring device is necessary. Therefore, in this study, we will investigate whether the shaping conditions can be determined from the concentric circle spreading out of the container after vibrating the gel contained in the cylindrical container with the diaphragm. Also, We will confirm whether or not it is possible to measure simple kinematic viscosity of a high viscosity material by checking the presence or absence of concentric circle spread and viscosity relationship.
Development of Electrochemical Nanosensor for the Detection of Malaria Parasite in Clinical Samples
Authors: Adekunle Abolanle Saheed , Obisesan Olaoluwa R. , Oyekunle John A.O. , Thomas Sabu , Nkambule Thabo TI , Mamba Bhekie B.
Published: February 2020

Malaria is an intricate, infectious, hematologic disease instigated by a protozoan parasite named Plasmodium falciparum (Priyamvada et al., 2014). The parasite lives part of its life in human and part in Anopheles mosquitoes. Malaria is the fifth most common cause of death in the world due to its infectious characteristics and the second in Africa, after HIV/AIDS (WHO, 2000). Development of sensitive, selective, accurate, rapid as well as cheap techniques for clinical diagnosis has been the major focus of researchers recently. Electrochemical sensors using nanoparticles have emerged as one of the suitable technologies for the detection of analytes of interest in clinical chemistry due to their high sensitivity and selectivity, rapid response time and low-cost (Wang, 1994). Beta-hematin have been extensively explored for the synthesis of antimalaria drugs and can also serve as a biomarker for the diagnosis of malaria. It is a microcrystalline cyclic dimer of ferriprotoporphyrin IX (Fe(III)PPIX) in which the propionate side chain of one protoporphyrin coordinates to the iron(III) center of the other. In this study, Electrochemical nanosensors were developed from the synthesised metal oxide (MO) nanoparticles by supporting it on a gold electrode (Au). The activity of the developed nanosensor towards the detection of malaria biomarker (β-hematin) was determined and the optimum conditions at which the maximum detection and quantification occurred was established. β-Hematin current response at the sensors was higher compared with the bare Au electrode and followed the order Au-CuO (C) > Au-CuO (M) > Au-Fe₂O₃ (M) > Au-Fe₂O₃ (C) > Au-Al₂O₃ (M) > Au-Al₂O₃ (C) > bare Au. The developed sensors were stable with a relatively low current drop (10.61 - 17.35 %) in the analyte. Au-CuO sensor has the best performance towards the biomarker and quantitatively detected P. berghei in infected mice’s serum samples at 3.60 – 4.8 mM and P. falciparum in human blood serum samples at 0.65 – 1.35 mM concentration. The developed sensor detected malaria biomarker successfully without interference from typhoid signal solving the problem of clinical diagnosis confusion of malaria and typhoid diseases.

Keywords: β-hematin, Metal Oxide Nanoparticles, Sensor, Cyclic Voltammetry, Square Wave Voltammetry

References

Priyamvada, J., Babina, C., Sanjukta, P., and Pranab, G. (2014). Potential Biomarkers and Their Applications for Rapid and Reliable Detection of Malaria. Hindawi Publishing Corporation BioMed Research International, Volume 2014, Article ID 852645, 20 pages.

WHO (2000). Malaria diagnosis new perspectives: report of a joint WHO/ USAID informal consultation. Geneva: World Health Organization 2000, 1–57.

Wang, J. (1994). Analytical Electrochemistry, VCH Publishers Inc. New York
Direct Patterning of Antibody Conjugated Gold Nanorods Immunoassay for the Label-Free and Multiplexed Determination of Mouse Tumor-Associate Macrophages Functional Immunophenotype
Authors: He Jiacheng
Published: February 2020

Plasmonic nanoparticle patterning has been extensively investigated over the past decades for its vast applications in miniaturized electronics, enhanced electrochemical catalysts and integrated biosensors. Current available techniques, such as electron beam lithography, dip-pen nanolithography, scanning probe microscopy-based patterning, microfluidics, and inject printing, provide multiscale capability for nanoparticle fabrication, manipulation and self-assembly patterning. However, it remains critical challenging to achieve uniform patterning via a low cost template-free method with high throughput and scalability. Herein, we report a facile method to direct pattern antibody conjugated gold nanorods (AuNRs) on a (3-Aminopropyl)triethoxysilane functionalized glass substrate in one-step manner by employing the anisotropic microstructure of weasel hairs. We successfully fabricated parallel uniform barcode nanoparticle ensembles with fine controlled widths on glass substrates over a 5cm×2cm area within less than three minutes using minimum of 3 uL AuNR solution. The fabricated device was applied as real-time and multiplexed immunoassays for functional immunophenotyping of mouse tumor-associate macrophages (TAMs) in response to BLZ in a tumor microenvironment. This nanoparticle patterning technique can be further extended to other clinical applications, such as disease diagnosis and immune status monitoring.
A Nano Sensor Array for Methyl Salicylate Detection in Gaseous Form
Authors: Zolti Or , Ramasamy Ramaraja P.
Published: February 2020

Pathogenic plant diseases can be recognized through volatile organic compounds (VOC) chemical markers that are emitted from the plant surface upon distress. The ability to detect biomarkers from distressed plants sensitively, selectively, accurately, and rapidly could be of enormous benefit to the agricultural industry and crop growers. Among the various VOC, Methyl Salicylate (MeSa) has been identified to be a fingerprint compound that can be used as chemical marker for early detection of diseased crops1,2. Carbon nanotube (CNT) based sensors have been long used in detection of molecular species, due to their extremely high surface to volume ratio, and their p-type semiconducting behavior when connected to metallic electrode3. In this work the development of a CNT-based amperometric gas sensor for MeSa has been undertaken. The CNT gas adsorption capabilities result from their hollow structure and nanometric dimensions. These properties are important for sensitivity as it allows for several molecules to adsorb on to the surface of the sensor. The detection of MeSa is done by monitoring the current flowing through the CNT under specific gate-drain and source-drain potentials. These potentials are determined by careful examination of the change in current under different gate potentials (Trans-conductance) and the change in current under different source-drain potentials. When the MeSa molecule is adsorbed to the CNT surface it behaves as an additional gate potential source and therefore changes the current in the CNT. Selectivity can be achieved with different surface modifications of the CNT. The surface modifications will change the potential the MeSa induces on the CNT, and thus gives a different current profile for the adsorption and desorption of the MeSa molecules to and from the CNT surface.
Wireless Stretchable Hybrid Electronics for Smart, Connected, and Ambulatory Monitoring of Human Health
Authors: Kim Yun-Soung , Mahmood Musa , Kwon Shinjae , Herbert Robert , Yeo Woon-Hong
Published: February 2020

Continuous ambulatory cardiac monitoring using electrocardiogram (ECG) can reveal a range of essential health conditions. However, commercially available devices rely on bulky wires, rigid sensors/electronics and cause great discomfort that disrupts one’s lifestyle and prevents long-term use. Moreover, standard gel-based electrodes are prone to degradation over long-term use and can causing allergic skin reactions. Also, research-level skin-wearable devices, while excelling in few aspects, fall short as concept-only presentations, due to the fundamental challenges in active wireless communication and integration as a single device platform.

Here, we introduce a fully wireless, low-profile, multifunctional stretchable hybrid electronic (SHE) device that offers smart, connected, and ambulatory health monitoring. As shown in Figure 1, the low-modulus, elastomeric system construction provides the gentle, yet sufficient, device adhesion to skin, obviating the need for straps, tapes, or adhesives, and demonstrates a type of monitoring scheme inconspicuous not only to the observer, but also to the user. Integration of a set of stretchable nanomembrane sensors with a highly flexible, membrane-based wireless circuit enables the continuous, long-range (up to 15 m) monitoring of ECG, heart rate, respiratory rate, and physical activities. Implementation of convolutional neural networks and algorithms for real-time classifications of multi-modal physiological signals demonstrates the device feasibility for multi-faceted clinically relevant analysis. In vivo demonstrations involving human subjects both with and without cardiac conditions reveal the feasibility of the device as a continuous, ambulatory, and multifunctional health monitor with emphasis on real-time detection of cardiac abnormalities. Further in vivo demonstration of SHE applied on athletes during treadmill exercises validate the versatility of SHE in both clinical and research environments.

Figure 1: Overview of SHE. (A) Photograph showing the stretchable hybrid electronics applied on human chest. (B) Blow-up render detailing the structural components of SHE including the thin-film stretchable skin electrodes, hyperelastic membranes, mechanical decoupling chamber, stretchable connector, and flexible data acquisition unit.

Figure 1
Ultra-Stretchable Conductive Polymer Complex As a Wearable Strain Sensor with Excellent Linearity and Repeatable Autonomous Self-Healing Ability
Authors: Lu Yang , Horne Jesse , McLoughlin Lauren , Ploeger Rachel , Jeon Ju-Won , Wujcik Evan K
Published: February 2020

Wearable strain sensors are essential for the realization of applications in the broad fields of remote healthcare monitoring, soft robots, immersive gaming, among many others. These flexible sensors should be comfortably adhered to skin and capable of monitoring human motions with high accuracy, as well as exhibiting excellent durability. However, it is challenging to develop electronic materials that possess the properties of skin—compliant, elastic, stretchable, and self-healable. This work demonstrates a new regenerative polymer complex composed of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA), polyaniline (PANI) and phytic acid (PA) as a skin-like electronic material. It exhibits ultrahigh stretchability (1935%), excellent repeatable autonomous self-healing ability (repeating healing efficiency > 98%), and exceptional linearity (R2
> 0.995) — outperforming current reported wearable strain sensors. The deprotonated polyelectrolyte, multivalent anion, and doped conductive polymer, under ambient conditions, synergistically construct a regenerative dynamic network of polymer complex crosslinked by hydrogen bonds and electrostatic interactions, which enables ultrahigh stretchability and repeatable self-healing. Sensitive strain-responsive geometric and piezoresistive mechanisms of the material owing to the homogenous and viscoelastic nature provide excellent linear responses to omnidirectional tensile strain and bending deformations. Furthermore, this material is scalable and simple to process in an environmentally-friendly manner, paving the way for the next generation flexible electronics.

Figure 1
Microfluidics Enhanced Performance of Electrochemical Devices
Authors: Stetter Joseph R.
Published: February 2020

The design of electrochemical [amperometric] gas sensors [the AGS] involves consideration of materials, geometry, structure and methods of operation as well as supporting electronics; in other words it is a systems problem to make a practical sensors within size and cost constraints that will meet all performance requirements for a given market. This work examines the construction of an AGS for atmospheric pollutants [Ozone, CO, NO2] that combines microfluidic sample inlet with cell designed to operate over a wide range of RH, Pressure, and Temperature encountered in smart cities, IoT deployment. Not only is ppb sensitivity required, but also multiyear stability of both span and background currents as well as a MTBF [mean time between failure] measured in decades. The approach to design, fabrication, testing, and deployment as well as field data are presented. Overall assessment of the advantages of electrochemistry as well as limitations and challenges are discussed. to be entered later
Lithium Cycling, Limiting Current, and Electrochemical Characterization in Solid Polymer Electrolytes
Authors: Maslyn Jacqueline A. , Frenck Louise , Balsara Nitash P.
Published: February 2020

Successful prevention of lithium dendrite growth would enable the use of lithium metal as an anode material in next-generation secondary batteries. Mechanically stiff solid polymer electrolytes have been shown to prolong the life of lithium metal cells by partially suppressing lithium dendrite growth. A series of diblock copolymers of high modulus and molecular weight were synthesized, and their nanostructures and electrochemical properties were characterized as a function of polymer composition and lithium salt concentration, including measurements of the limiting current. X-ray tomography was used to observe lithium metal plating and cycling through these solid polymer electrolyte membranes under a range of electrochemical conditions. Insight into the interplay between electrochemical and mechanical properties, polymer microstructure, and lithium electrodeposition morphology will aid in the design of next-generation electrolytes.
Unique Development of Bimetallic Pt3Ni1 Octahedral Structures for Increased Oxygen Reduction Activity
Authors: Weiss John , Payattikul Laksamee , Shimpalee Sirivatch , Weidner John , Punyawudho Konlayutt
Published: February 2020

Deviations from commercially accepted Pt electrocatalysts have been widely investigated in order to improve activity for the oxygen reduction reaction (ORR) within polymer electrolyte membrane fuel cells (PEMFCs). For this research, PtNi bimetallic catalysts were synthesized with the particular focus of producing novel octahedral structures, which have theoretically exhibited a specific activity up to 90 times larger than Pt counterparts. With a predetermined molar ratio of Pt3Ni1, the bimetallic catalyst of interest was synthesized through a unique solid-state procedure, and the existence of octahedral structures were confirmed through Transmission Electron Microscopy (TEM). When tested through cyclic and linear sweep voltammetry against Pt/C and Pt3Ni1/Graphene, the Pt3Ni1/C catalyst exhibited the highest specific activity (SA), while maintaining a strong electrochemical surface area (ECSA). Through accelerated durability testing (ADT) over 4,000 cycles, the Pt3Ni1 catalyst experienced noticeable degradation, leaving room for further improvement of this particular catalyst. However, this research was able to successfully produce highly active Pt3Ni1 octahedral structures through a novel solid-state method, which offers increased potential in practical fuel cell applications.
Effect of Alcohol Addition to Sulfuric Acid on Efficiency for Formation of Anodic Alumina
Authors: Matsumoto Mikimasa , Hashimoto Hideki , Asoh Hidetaka
Published: February 2020

Anodization of aluminum in electrolytes containing alcohols as an additive has been studied for improvement of coating properties such as corrosion and wear resistance, and hardness. The influence of the addition of alcohols on the pore arrangement in anodic alumina was also investigated. However, the essential understanding of the effect of alcohol addition is still insufficient. In this study, we used the sulfuric acid-based electrolyte containing various alcohols (e.g., methanol, ethanol, glycerol, and ethylene glycol) as an additive and investigated the effects of types and concentrations of alcohols on the efficiency for the oxide formation and the structure of the porous alumina.

High purity aluminum sheets were used as a starting material and anodized at constant current of 100 A m-2 in 1.5 mol dm-3 sulfuric acid with alcohol concentration in the range of 0~50 vol%. The formation of porous alumina film on the aluminum substrate was investigated by measuring voltage transient. In the case of ethanol concentration less than 10 vol%, voltage-time curve shows the steady-state voltage of approximately 15.7 V. When ethanol concentration exceeded 20 vol%, the steady-state voltage obviously increased with increasing ethanol concentration. In sulfuric acid without ethanol addition, the surface layer of oxide film was excessively dissolved after anodization for 220 min. The film thickness was approximately 65 μm. While using sulfuric acid with 50 vol% ethanol, chemical dissolution of the outer surface was significantly suppressed and the film thickness increased from 65 μm to 70 μm at the same anodization time, i.e., the same electric charge. Even in other type of alcohols, chemical dissolution of oxide was suppressed, resulting in improvement of coulombic efficiency for the oxide formation. The variation of dissociation constant of the electrolyte by addition of alcohols might affect the chemical dissolution and formation efficiency of anodic film.

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Articial Neural Networks for Accurate Prediction and Analysis of Perovskite Bandgaps
Authors: Stoichev Zlatomir , Allam Omar Adel , Jang Seung Soon
Published: February 2020

Perovskites are a unique class of semiconductors with long carrier diffusion lengths which have shown remarkable promise for photovoltaic applications as their solar conversion efficiencies increased rapidly by nearly 20% over the past decade. Here we evaluate the efficacy of artificial neural networks for the analysis and prediction of 3D perovskite band gaps; which is the key parameter used in solar cell design. The set of input parameters for our artificial neural network includes descriptors such as s, p, d, and f orbital radii, electronegativity, octahedral factor, and formation energy. Furthermore, we apply a recursive feature correlation filter to eliminate features which highly correlate with other features in our model as well as features which have a low contribution with regards with regards to predicting bandgap. We find that splitting the dataset between training, testing, and validation sets in a 70:15:15 ratio provides a highly reliable model that yields a mean square error of less than 0.25 eV. We then validate the capability of artificial neural network by testing its predictability for bandgaps based on unseen inputs.