bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetoelastic Biosentinels for the Detection of Pathogenic Bacteria in Stagnant Liquids
Authors: Horikawa Shin , Chai Yating , Du Songtao , Wikle Howard Clyde , Chin Bryan A
Published: February 2020

This paper presents an investigation into magnetoelastic (ME) biosentinels that seek out, capture, and detect target pathogens in stagnant liquids. The ME biosentinels are designed to mimic various types of white blood cells, the main defensive mechanism in the human body against different pathogenic invaders. This nature-inspired ME biosentinel is composed of a freestanding ME resonator coated with a landscape phage that is engineered to bind specifically with the pathogen of interest. When subjected to an externally applied alternating magnetic field, the biosentinel can be placed into mechanical resonance (i.e., bending or longitudinal mode of vibration) by magnetostriction. The resonating biosentinel can then move autonomously through a liquid due to the net acting force and fluid-structure interactions. As soon as the biosentinel finds and binds with the target pathogen, changes in the mass as well as resonant frequency of the biosentinel occur, and thereby the presence of the target pathogen can be detected. Due to the wireless nature of detection, the resonance frequency changes can be measured in real time without any physical connection to a detector (by using a designed electromagnetic coil and a network analyzer operating in the reflection mode). In order to actuate the biosentinel into mechanical resonance of a desired mode, modal analysis using the three-dimensional finite element method was first performed, followed by determination of the resonant frequency. In addition, the net acting force and resultant motion of the biosentinel due to the induced mechanical vibration were calculated. As a model study, this paper presents detection of Bacillus anthracis spores, a Category A bioterrorism agent, under stagnant flow conditions. Both dynamic simulation and experimental results showed that the ME biosentinels can move autonomously through the liquid and actively bind with the target pathogen. This investigation will advance the fundamental scientific theories describing the operation of biosentinels and have broad societal impact by improving human health through earlier detection of pathogens. Potential short-term applications include the capture and detection of pathogenic bacteria in liquid food products such as juices and milk.
Comparison of Electroreduction of Sulfur Dioxide in Ionic Liquid at Gold and Platinum Electrodes
Authors: Guo Min , Zeng Xiangqun
Published: February 2020

The electrochemical reduction of sulfur dioxide (SO2) has been studied in ionic liquid (IL) 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf2]) at gold and platinum electrodes by cyclic voltammetry and in-situ electrochemical quartz crystal microbalance. A mechanism for the electrode reaction was proposed that the main process in the reduction was one electron-transfer process and the product was stable SO2
-• radical anion. While two anodic peaks were observed on the oxidation wave at both working electrodes. The anodic peak which appeared at a less negative potential was assigned to the oxidation of free SO2
-• radicals. However, the peak appearing at more positive potential was assigned to the oxidation of SO2
-• which was solvated into IL electrolyte on the electrode surface. Comparing gold and platinum electrodes, the gold electrode gave a better sensitivity due to the interaction between sulfur and gold surface. Based on the above proposed SO2 electrochemical reduction mechanism, real time SO2 detection by amperometric method was also investigated. The results demonstrated that the detection limit and sensitivity for SO2 was 39.4 ppm and 99 µA/[%SO2], respectively, in [Bmpy][NTf2] at gold electrode. A stable response was able to achieve over 30 days. Because of the attractive physical properties of ILs (e.g., less volatile and high thermal stability), the utilization of IL provides a novel electrochemical approach to develop a robust SO2 sensor.
The Effect of Carbon Nanotubes Solid Contact Dispersing Agent on the Parameters of Resulting Potentiometric Sensors
Authors: Michalska Agata , Jaworska Ewa , Maksymiuk Krzysztof
Published: February 2020

Carbon nanotubes are important nanostructured material for different applications, including electrochemical sensors [1,2].   Among other advantages related to electrochemical properties of carbon nanotubes, they can be applied in simple procedure, resulting in electronically conducting layers. For sensor purposes (e.g. ion-selective electrodes, field effect-transistors) carbon nanotubes (CNTs) suspension (called ink) can be simply drop cast or spray coated on different substrates. However, to prepare a useful and stable CNTs suspension in water application of stabilizing agent is necessary. This agent is usually an ion or polymer that spontaneously absorb on CNTs – e.g. sodium dodecylsulfate, sodium dodecylbenzene sulfate or carboxymethyl celulose [1-4]. As a consequence this substance is present also in obtained CNTs layer and potentially can affect their performance.

In this study potassium selective electrodes with CNTs solid contact were prepared. The CNTs transducer layers were obtained by drop casting, using suspensions stabilized with different agents – surafctants as well as complexing ligands. The effect of CNTs suspension stabilizing agent on performance of potentiometric sensors - analytical parameters (sensitivity, selectivity, detection limit) as well as stability of potentiometric responses in time were studied. Potentiometric (open circuit), chronopotentiometric and impedance studies have confirmed that the nature of  dispersing agent used as well as its amount used affects performance of the sensor. Dispersing agent used can partition into sensor layers – e.g. ion-selective membrane - significantly altering their properties. Herein obtained results are potentially important for all applications in which CNTs layer are fabricated using stable dispersion of nanomaterial. 

REFERENCES

1.   G. A. Crespo, S. Macho, F. X Rius, Anal. Chem. 2008, 80. 1316.

2. F. X. Rius - Ruiz, G. A. Crespo, D. Bejarano - Nosas, P. Blondeau, J. Riu, F. X. Rius, Anal. Chem. 2011, 83, 8810. 

3. K. Melzer, A. M. Münzer, E. Jaworska, K. Maksymiuk, A. Michalska, G. Scarpa, Analyst 2014, 139, 4947

4. E. Jaworska, M. Schmidt, G. Scarpa, K. Maksymiuk, A. Michalska Analyst 2014, 139, 6010.
Spray-Coated All-Solid-State Potentiometric Sensors
Authors: Jaworska Ewa , Schmidt Morten , Scarpa Giuseppe , Maksymiuk Krzysztof , Michalska Agata
Published: February 2020

Recent reports on application of nanostructurized materials for potentiometric sensing purposes  point out advantages of novel structures [1]. Here a methods of ions-selective electrodes preparation using solely spray coating method was reported [2]. As an electrical lead support and transducer  spray coated CNT layers were used. The ion-selective membrane was coated also by spraying membrane cocktail over a part of a CNTs layer. This method offers significant advantages compared to screen-printed electrodes used also for potentiometric applications [3]. The benefits of the herein-proposed approach include fully automatic sensor preparation and minimized use of chemicals allowing for the production of low-cost sensors that can be applied as disposables. The obtained sensors (as the model system potassium-selective sensors were prepared) are characterized with analytical parameters well comparable with that of conventional, all-solid-state, ion-selective electrodes. In addition, the applicability of the herein-proposed approach to prepare other ion-selective electrodes was tested on examples of H+  and Cl- sensors.

REFERENCES

1. A. Düzgün, G.A. Zelada-Guillén, G.A. Crespo, S. Macho, J. Riu, F.X. Rius, Anal. Bioanal. Chem., 2010, 399, 171-181.

2. E. Jaworska, M. Schmidt, G. Scarpa, K. Maksymiuk, A. Michalska, Analyst 2014, 139, 6010-6015.

3. R. Koncki, Ł. Tymecki, E. Zwierkowska and S. Głab, Fresenius. J. Anal. Chem., 2000, 367, 393.
Percolation Pressure of Droplets Emerging through Pores: Geometrical and Pinning Considerations
Authors: Herescu Alexandru
Published: February 2020

We examine numerically the correlation that exists between the pore geometry and pinning conditions, and the percolation pressure. The droplet formation process is relevant to water transport through the Gas Diffusion Layer (GDL) into the gas flow channels of PEM fuel cells. The percolation pressure of individual droplets forming at the GDL surface will be eventually reflected into the water distribution on the respective side of the channel.
Metal Halides in Li-Ion Batteries
Authors: Bridges Craig A , Powell Jonathan M , Veith Gabriel M , Banerjee Arnab , Nagler Stephen E. , Dai Sheng
Published: February 2020

There is a critical need for improved electrical energy storage in terms of capacity, voltage, recharge time, safety and cost for a renewable energy grid, practical electric vehicle technology, and future portable energy technology. One approach under consideration to overcome current limitations in lithium ion batteries is to utilize a multielectron conversion electrode. [i] Much focus has been placed on the use of metal fluorides for secondary batteries, due to promising cell voltages and chemistry. Here we present recent work looking at the use of metal chlorides, and understanding the mechanism of lithiation and delithiation.

 [i] Gao, X.-P.; Yang, H.-X.; “Multielectron reaction materials for high energy density batteries”, Energy Environ. Sci.
3 (2010) 174-189.
Optimization of Dispersion Property of a Thin Ceramic-Coating Layer on Thermal and Electrochemical Properties of Separator for Lithium-Ion Batteries
Authors: Kim Hyunsik
Published: February 2020

In this poster, a optimized dispersity propery of ceramic-coating separator for lithium-ion batteries is successfully prepared by forming a ceramic layer consisted of Al2O3 powder and mix binder onto one side of pristine PE separator.

During the preparation of the separator, water is used as solvent and a very small amount of a mixture binder is applied as binder to obtain better thermal stability. The effect of dispersity property of the ceramic-coating layer on its thermal stability, physical properties and electrochemical performance is also investigated. The results clearly showed that the ceramic-coating separator with SBR–CMC binder has wonderful thermal stability, good wettability and high uptake of liquid electrolyte.
Synthesis at Low Cost and Large Scale of Silicon Powder Suitable for Li-Ion Anodes
Authors: Reale Hernandez Cuauhtemoc , Karkar Zouina , Guyomard Dominique , Lestriez Bernard , Roué Lionel
Published: February 2020

Silicon is considered as one of the most promising materials to replace graphite in Li-ion batteries. The main inconvenient of that material is its huge volume expansion during lithiation which induces the disintegration of the electrode architecture with cycling. Nanosized Si materials (nanoparticles, nanowires, nanocomposites…) better accommodate large volume variation without cracking. However, the use of such materials by industries is unlikely because of their high synthesis cost, handling difficulties and low tapping density.  

We have recently demonstrated that Si powder produced by high-energy ball milling (using a laboratory vibratory-type miller) present the same benefits of nanometric Si in terms of performance but not the drawbacks1. Milled Si powder is constituted of micrometric agglomerates (median size of ca. 10 µm), made of submicrometric cold-welded particles with a crystallite size of ca. 10 nm. The micrometric particle size provides handling and non-toxicity advantages compared to nanometric powders, as well as four times higher tap density. The nanocrystalline structure of the ball-milled Si powder is assumed to induce a smoother phase transition upon cycling.1,2

In the present study, ball-milled Si powder is produced at larger scale (500 g/batch compared to 5g/batch in previous work) using a pilot-scale attritor (Fig. 1).  Using optimal milling parameters and appropriate composite electrode formulation, this material displays very good electrochemical performance (see Fig. 2). Various analyses will be presented in order to understand the influence of the milling time on the physicochemical characteristics and electrochemical behavior of the Si powder. During these investigations, we noticed that the storage conditions of the electrodes prior to assembling the cell have also a major influence on the electrochemical performance. This aspect will be also discussed.

References

1. M. Gauthier, D. Mazouzi, D. Reyter, B. Lestriez, P. Moreau, B. Lestriez, D. Guyomard, L. Roué. A low-cost and high-performance Si-based electrode for Li-ion batteries. Energy Environ. Sci. 6 (2013) 2145–2155.

2. M. Gauthier, D. Reyter, D. Mazouzi, P. Moreau, D. Guyomard, B. Lestriez, L. Roué. From Si wafers to cheap and efficient Si electrodes for Li-ion batteries. J. Power Sources 256 (2014) 32-36.

Figure 1
Ccto-P(VDF-CTFE) 0-3 Composites for Energy Storage Application
Authors: Tong Yang , Zhang Lin , Cheng Z.-Y.
Published: February 2020

ABSTRACT

Recently, there is a great need to develop a new ceramic-polymer composite which exhibits relatively high dielectric constant, high dielectric strength, low dielectric loss and high flexibility for applications ranging from electronic packaging, embedded capacitors, to energy storage [1, 2]. The electric energy density (Ue) can be calculated by the equation Ue=1/2ε0εrEb
2, where ε0 is the vacuum permittivity (8.85×10-12 F/m), εr is dielectric constant of composite, and Eb is dielectric breakdown field. A higher dielectric constant or dielectric strength would allow a higher energy density, are highly desirable for the dielectrics used in energy storage devices [2]. Ceramic-polymer composites have been detail studied by researchers, and most of the recent studies were focused on the PVDF-based composites.

In this experiment, the nano-sized CaCu3Ti4O12 powder and P(VDF-CTFE) 88/12 mol.% are used for prepare composites by solution cast with high dielectric constant in previous work [3, 4]. To enhance the uniform distribution of ceramic filler in polymer matrix, the CCTO powder was firstly coated with the coupling agent 1 H, 1H, 2H, 2H Perfluorooctyltrichlorosilane, which can be used to improve the dielectric breakdown field. The coated powder was mixed with P(VDF-CTFE) in dimethyl formamide (DMF) solution then casting as thin film at 70oC and annealed with different temperatures. The dielectric constant and dielectric strength of the composites were studied using Impedance Analyzer and H.V. Supply Amplifier/Controller respectively. The annealing effect, amount of coupling agent and temperature dependence of dielectric properties were studied for these composite films. The energy density in these nanocomposites can reach around 4.5 J/cm3 with volume fraction of CCTO around 15 vol.%, which makes them attractive for high energy density capacitors and electric energy storage devices.

REFERENCES

[1] B. Chu, X. Zhou, K. Ren, B. Neese, M. Liu, Q. Wang, F. Bauer and Q. M. Zhang, “A dielectric polymer with high electric energy density and fast discharge speed,” Science vol.313, 334-336, 2006.

[2] Z. M. Dang, J. K.Yuan, S. H. Yao, and R. J. Liao “ Flexible nanodielectric materials with high permittivity for power energy storage,” Adv. Mater., vol. 25, pp. 6334-6365, 2013.

[3] L. Zhang, X. B. Shan, P. X. Wu and Z.-Y. Cheng, “Dielectric characterization of CaCu3Ti4O12/P(VDF-TrFE) nanocomposites,” Appl. Phys. A, vol. 107, pp. 597-602, 2012.

[4] X. B. Shan, L. Zhang, X. Q. Yang, and Z.-Y. Cheng, “Dielectric composite with a high and temperature-independent dielectric constant,” J. Adv. Ceram. Vol.1, pp. 310-316, 2012.

Figure 1
Dissolution and Repassivation Behaviour of Ti, Ti-6Al-4V, Type316L and Co-27Cr-5.5Mo in Bio-Mechano-Chemical Environment
Authors: Doi Kotaro , Miyabe Sayaka , Fujimoto Shinji
Published: February 2020

Dissolution and Repassivation during and after passivity breakdown of four kinds of metallic biomaterials in simulated body fluid were examined using rapid straining electrode test. The materials were pure titanium, Ti-6Al-4V alloy, type 316L stainless steel and Co-Cr alloy. Rapid straining was applied for electrodes of these materials that were immersed in a simulated body fluid containing proteins for 1 day, 1 week or 1 week with cell culturing prior to the test, then changes in strain, stress and anodic current were observed simultaneously.

The maximum anodic current density during rapid straining was observed for pure titanium. However, maximum charge density generated after rapid straining until 100 s from the termination of rapid elongation was observed for type 316L stainless steel. These results suggest that the amount of dissolution of metallic biomaterials with passivity breakdown depends on the equilibrium potential of metal substrates and repassivation rate.

The charge densities generated on the samples immersed for 1 week in the simulated body fluid prior to the rapid elongation and covered with cells was larger than that generated on the sample immersed for 1 day in pure Ti, Ti-6Al-4V alloy and type 316L stainless steel. The highest increase rate of the charge density was confirmed in the sample covered with cells of type 316L stainless steel.
Heterogeneous Thermal Oxide Film Formed on Polycrystalline Pure Iron
Authors: Takabatake Yu , Kitagawa Yuichi , Nakanishi Takayuki , Hasegawa Yasuchika , Fushimi Koji
Published: February 2020

The thermally-grown oxides formed on pure iron have characteristic composition, structure, and thickness, depending on the oxidation condition such as temperature and oxygen partial pressure. The crystallographic orientation of iron surface also affected the rate of thermal oxidation1. However, the heterogeneity on the thermal oxide film formed on polycrystalline iron has not been discussed sufficiently. In order to well understand the non-uniform oxidation that progresses on polycrystalline iron, it is important to elucidate the precise characteristics of the thermal oxide film from the viewpoint of crystallographic orientation. In this study, we investigated the heterogeneity of thermal oxide film formed on polycrystalline pure iron by using a 2D-ellipsometer and a micro-capillary-cell (MCC) method2.

The sample specimen was an annealed iron plate with a purity of 99.99%. After mirror-like polishing, the surface orientations of the sample were identified by using an electron backscatter diffraction patterning. Subsequently, the sample was kept at 573 K in air for 3.6 ks to form thermal oxide film. The thickness of the oxide film on the surface was mapped with the 2D-ellipsometer. The characteristics of the oxide film formed on each single grain were evaluated by electrochemical impedance spectroscopy (EIS) by means of an MCC with an inner diameter of 180 µm.

The sample surface as polished was smooth like a mirror showing metallic luster. After thermal oxidation, however, it showed various colors, depending on the surface metallographic structure due to interference of light. The colors of the sample surface indicated that the thermal oxides grew at different rate depending on the surface orientation of single grains on the substrate. The non-uniform oxide formation on the polycrystalline iron was also confirmed by two-dimensional thickness mapping with the ellipsometer. EIS measurements showed that the electric resistance and capacitive behavior of the oxide films were depended on the orientation of substrate surface. Furthermore, the results of Mott-Schottky analysis implied that the surface orientation affected the defect structure of the thermal oxides. It was considered that the grain-dependency on the thermal oxide film was originated in anisotropic growth of the oxide determined by the crystallographic orientation of the substrate iron surface. The detailed consideration of the grain-dependency on the oxide film is discussed on site.

References

[1] W. E. Boggs, R. H. Kachik, and G. E. Pellissier, J. Electrochem. Soc., 114, 32 (1967).

[2] Y. Takabatake, K. Fushimi, T. Nakanishi, and Y. Hasegawa, J. Electrochem. Soc., 164, C594 (2014).
Factors Affecting Stray Currents Corrosion of Buried Pipeline
Authors: Qingjun Zhu , Baorong Hou
Published: February 2020

Pipelines are becoming more and more familiar in modern society. Although they are effective seemingly, most of these pipelines are influenced by various corrosions. Stray current corrosion is the most severe form of corrosion because the metallic structure is forced to become an anode and the amount of current can be translated directly into metal loss. One ampere of DC current discharge from a pipeline/well casing for one year may consume 10kg of steel. Stray current is a key role in producing pipeline corrosion. However, it is very complicated to control stray current corrosion because many factors can affect the current flowing between the source and pipelines. Pipeline design and maintenance require factors influencing stray current corrosion. In this paper, soil resistivity, coating worn rate, buried depth and horizon distance have been studied. The specific factor influencing stray currents corrosion are studied by the method of keeping other elements fixed. The results show stray current can be influenced by soil resistivity, coating worn rate and buried depth in different degree. It is favorable to control stray current corrosion by increase soil resistivity, buried depth and horizon distance or decrease coating worn rate. There are boundary values in controlling stray current corrosion by increasing soil resistivity, buried depth and horizon distance. In this laboratory study, the boundary horizon distance is 200mm.
Effects of Temperature on the Corrosion Potential of Stainless Steel Under Gamma-Ray Irradiation
Authors: Satoh Tomonori , Kato Chiaki , Ueno Fumiyoshi
Published: February 2020

The structural materials of the instruments used in Fukushima Daiichi nuclear power station are exposed to the corrosive condition under the gamma-ray irradiation.  In order to determine the effects of the temperature of water under gamma-ray irradiation on the corrosion potential of stainless steel, the measurements of the corrosion potential under gamma-ray irradiation condition was performed.  The dissolved oxygen concentration was aerated condition in each temperature in this study.  And the corrosive condition under the irradiation was evaluated by the water radiolysis calculation and the measurements of the included hydrogen peroxide in the water after the irradiation.  As parameters, the temperature of water and the gamma-ray dose rate were changed.  The major results are listed as follows;

(1)     The corrosion potentials rose about 400 mV by the gamma-ray irradiation in all temperature conditions.

(2)     The potential was low with higher temperature under irradiation with the aerated condition.  It was assumed that the lower dissolved oxygen concentration with higher temperature will cause the dependency of the corrosion potential on the temperature under irradiation.

(3)     The generation of some ppm of hydrogen peroxide was confirmed by the measurements of hydrogen peroxide concentration.  It was indicated that the increase of the corrosion potential by the irradiation was caused by the generation of the high concentration of hydrogen peroxide. 

(4)     It was confirmed that the generation of hydrogen peroxide was lower in higher temperature condition due to the lower dissolved oxygen concentration in high temperature.  It was indicated that lower potential in high temperature water was caused by not only lower dissolved oxygen but also lower generation of hydrogen peroxide.
(Invited) Silicon Nanowires/Metal Nanoparticles Composites with Specific Properties
Authors: Boukherroub Rabah
Published: February 2020

In the past few years, there have been considerable advances in the synthesis and bio-applications of silicon nanowires (SiNWs). Because of their high surface area, electronic properties, biocompatibility, surface tailorability, multifunctionality and their compatibility with conventional silicon technology, SiNWs have been the focus of intense interest due to their potential applications in various fields including nanophotonics, biological/chemical sensors, microfluidics, and matrix-free laser desorption/ionization mass spectrometry substrates. Interfacing SiNWs with living cells and bacteria have been investigated in several reports with the aim to gain a better understanding on how these nanostructured substrates influence cell functions such as cell differentiation, adhesion and spreading.

 In this presentation, I will focus on the deposition of metal nanoparticles (Ag, Au, Ni, Cu) on SiNWs and their use for various applications ranging from SERS to anti-bacterial substrates. Moreover, given the high catalytic activity of noble metal nanocatalysts owing to their relatively high chemical activity and specificity of interaction, the resulting SiNWs/metal NPs have been successfully applied for various catalytic and photocatalytic transformations. Finally, the deposition of Cu NPs on SiNWs allowed the fabrication of affinity surfaces for specific capture of His-tag peptides and their subsequent analysis by matrix-free mass spectrometry.
Porosity Control and Transfer in Silicon Nanostructures through Electrochemical & Chemical Etching
Authors: Defforge Thomas , Vijayakumar Sanahan , Loni Armando , Chaix Arnaud , Sauldubois Audrey , Andreazza-Vignolle Caroline , Cunin Frederique , Di Renzo Francesco , Canham Leigh T , Gautier Gael
Published: February 2020

Porous silicon particles and nanostructures are receiving growing interest from the scientific community. Two important parameters usually used to define a porous material are porosity and pore size. However, internal surface area and pore morphology are also of high importance, as they determine the material performances in many applicative domains such as Li-ion batteries (1), catalysis, separation, drug delivery (2) etc.

High surface area porous silicon structures were prepared through silicon anodization in acidic HF electrolyte under galvanostatic control. The layers were then either taken off mechanically, forming powders, or subjected to a metal-assisted chemical etching (MaCE) post-treatment to produce high aspect ratio silicon nanowires through the depth of the porous film.

In the first scenario, careful attention was paid to the electrolyte composition in order to increase the internal surface area of the powders. In acidic solutions (i.e. HF mixed with strong acids such as HCl or H2SO4), powders with surface area exceeding 850 m²/g were achieved by lowering the average pore size to around 3 nm, whilst maintaining moderate porosity (~ 65%) (3).

In the latter scenario, MaCE (4) on porous silicon thin films facilitated the transfer of the parameters defining the mesoporous framework (porosity, pore diameter, surface area, pore orientation) from the thin film to high aspect ratio nanowires. This consisted of periodic modulation of the porosity with depth and applying MaCE post-treatment as illustrated by electron microscopy images, below, the nanowires clearly displayed the porosity gradient of the original porous silicon thin film.

The control of both anodization conditions, through an accurate choice of the silicon wafer doping type and level and electrolyte composition, to achieve ultra-high surface area porous powder, and porous layer post-treatment such as MaCE, to convert the porous framework from thin film to nanowires, provide new and promising opportunities in many application fields.

X. Li, M. Gu, S. Hu, R. Kennard, P. Yan, X. Chen, C. Wang, M.J. Sailor, J.G. Zhang and J. Liu Nat. Comm., 5, 4105 (2014).

C. Chiappini, X. Liu, J.R. Fakhoury and M. Ferrari, Adv. Funct. Mater., 20, 2231 (2010).

A. Loni, T. Defforge, E. Caffull, G. Gautier and L.T. Canham, Micro. Meso. Mater., (2015): DOI:10.1016/j.micromeso.2015.03.006

Z.Huang, N.Geyer, P.Werner, J.de Boor, U.Gosele. Adv.Mater23 : 285 (2011)

Figure 1
(Invited) Electrochemical Preparation and Processing of Porous Silicon Nanoparticles for Targeted, Self-Reporting Drug Delivery
Authors: Sailor M. J.
Published: February 2020

The electronic and optical properties that make the semiconductor silicon so useful for solid-state devices such as solar cells and microelectronics can also be harnessed for biological applications—in particular in vivo imaging and drug delivery.  This presentation will discuss the chemistry and photochemistry of nanostructured porous silicon.  The intrinsic photoluminescence that derives from quantum confinement and surface defect states provides a non-toxic and biodegradable luminescent probe for in vivo and in vitro imaging.  The luminescence properties are intimately tied to the surface chemistry of the material, and the relatively long (microseconds) excited state lifetime of this material can be harnessed for time-gated imaging or chemical sensing.  Applications in sensing, drug delivery, and targeted therapies will be discussed.
(Keynote) Oxide based Resistive Memories for Low Power Embedded Applications and Neuromorphic Systems
Authors: Vianello Elisa , Garbin Daniele , Jovanovic Natalija , Bichler Olivier , Thomas Olivier , de Salvo Barbara , Perniola Luca
Published: February 2020

The application potential of the new emerging resistive memories - as phase change memory (PCM), metal oxide resistive switching memory (OxRAM), conductive-bridge memory (CBRAM) or magnetic memories (MRAM) - covers the standalone memory technologies (as NAND and DRAM), but offers also potential for exciting new applications and markets, as new functionality coupled with logic circuits to enable block power-down, or use as synapses in neuromorphic circuits.

In this work, we will focus on the role that metal oxide resistive switching memory (OxRAM) can play in these new emerging fields of applications. Concerning the introduction of non-volatile functionality at the logic level, we will demonstrate hybrid (CMOS logic + ReRAM devices) circuits for Ultra Low Power (ULP) fixed-logic IC design (as Non Volatile Flip-Flops). Concerning neuromorphic circuits, we will focus on the emulation of synaptic plasticity effects with resistive memories synapses. We will show the implementation of large-scale energy efficient neuromorphic systems with deterministic multi-level synapses or stochastic-binary synapses. Prototype applications such as complex visual- pattern extraction will be also shown using Convolutional Neural Networks.
(Invited) Current Filamentation in Rram As Measured By High Speed Electrical Thermometry
Authors: Bain James A. , Sharma Abhishek , Skowronski Marek
Published: February 2020

In this paper, we review our method of measuring the local device temperature in oxide RRAM cells by taking high speed pulsed electrical measurements of the device I-V characteristics. These measurements are taken sufficiently fast (< 5 ns) as to avoid local joule heating of the device, revealing the device’s “true” room temperature I-V characteristics. Repeating these measurements as a function of stage temperature allows the construction of a unique I-V-T map, where T is the device temperature. This calibrated map can then be used under more general I-V interrogation where self-heating is present to extract the actual device temperature from I-V measurements. This method has been applied to a variety of RRAM-type oxide switches, including TiO2, Ta2O5 and HfO2 devices. Both pristine devices (prior to the initial filament forming breakdown step) as well as devices that have a filament present and can be repeatedly switched between high and low resistance states have been examined. The measurements show that internal device temperatures can range from 50ºC to 400ºC at the onset of the electroforming event, with temperatures above 600ºC when the event is completed. During switching, temperatures within the filaments peak at 300ºC-400ºC during each switching event. Temperature dependent resistivity measurements reveal that the filament has a metallic nature in materials like TiO2 (resistivity increases with increasing temperature) with a resistivity value of approximately 6000 nΩ-m. The surrounding matrix is semiconducting (resistivity decreases strongly with increasing temperature) and displays highly non-linear I-V curves. By combining the above thermometry technique with modeling of the thermal transport in the filament and its surrounding region, it is possible to get an estimate of the filament radius. Specifically, a unique filament radius is determined that self-consistently explains both the filament I-V behavior and slope of filament temperature vs dissipated power (the filament thermal resistance, Rth
). This analysis reveals that the filaments in oxide RRAM memory devices are typically 1 nm in diameter and have a hot zone around them that grows to several nm during the switching event. We are also able to apply this same analysis to the transient (i.e. non-permanent) current filaments that form prior to the permanent filament, during so-called threshold switching events. These measurements confirm for oxides the same picture reported in the literature for chalcogenide phase change materials many years ago - that a transient electrical current filament precedes the permanent structural one in these devices. Moreover, it is most likely that the heating within this transient filament that allows for the microstructural arrangement of the oxide atoms that results in a permanent conducting filament able to participate in the memory switching event.
(Invited) Integration Challenges of Ferroelectric Hafnium Oxide Based Embedded Memory
Authors: Müller Johannes , Polakowski Patrick , Paul Jan , Riedel Stefan , Hoffmann Raik , Drescher Maximilian , Slesazeck Stefan , Müller Stefan , Mulaosmanovic Halid , Schröder Uwe , Mikolajick Thomas , Flachowsky Stefan , Erben Elke , Smith Elliot , Binder Robert , Triyoso Dina , Metzger Joachim , Kolodinski Sabine
Published: February 2020

System on chip (SoC) embedded memory solutions promise small form factors and high operating speed, as well as a high energy and cost efficiency. Single cell scalability and basic memory parameters such as data retention, cycling endurance and disturb characteristics on array level are important aspects in stand-alone memory development and can serve as a guideline for embedded solutions. However, one of the key aspects in embedded memory development is compatibility of the memory technology to its underlying complementary metal oxide semiconductor (CMOS) platform. This includes the voltage requirements for logic and memory operation, the need for additional lithographic steps and minimally CMOS invasive integration efforts, as well as the introduction of new materials and related contamination concerns. Especially in state of the art high-k metal gate (HKMG) CMOS technologies at minimum feature size (F) these aspects proof rather challenging when searching for a suitable embedded memory solution. As a consequence most approaches result in large memory cells of multiple F2 or leave a BEoL integration of the memory cell as the only viable option.

With the introduction of ferroelectric hafnium oxide, however, a scalable one-transistor (1T) memory solution derived from the conventional HKMG transistor was presented for the 2X nm node. The therewith close resemblance of the memory and logic transistor appears ideally suited for combining nonvolatile data storage and logic circuitry on the same chip. Nevertheless, in order to fulfill these expectations and to ease manufacturing issues this resemblance has to be as close as possible. In the context of a minimally invasive memory integration strategy this means that ideally the ferroelectric hafnium oxide based memory transistor has to adapt to the HKMG transistor in terms of thermal budget and post treatments, vertical and lateral dimensions, the use of stress engineering, as well as metal gate and work function engineering. Based on experimental gate first transistor and metal insulator metal (MIM) capacitor data these aspects together with embedded memory requirements will be analyzed and critically discussed.
(Keynote) Status and Challenges in Spin-Transfer Torque MRAM Technology
Authors: Krounbi Mohamad , Nikitin Vladimir , Apalkov Dmytro , Lee Jangeun , Tang Xueti , Beach Robert , Erickson Dustin , Chen Eugene
Published: February 2020

Spin-transfer torque magnetic random access memory (STT-MRAM) has been considered as a promising candidate for next generation non-volatile memory due to a combination of fast speed, high endurance, excellent scalability, and ease of integration with the standard CMOS processes. While feasibility demonstrations used magnetic tunnel junction (MTJ) devices with an in-plane magnetization, significant advances in materials allowed implementation of the perpendicular MTJ design, which provides the best long-term scalability for STT-MRAM beyond 20 nm. Despite significant progress, there are many remaining hurdles in the productization of STT-MRAM. They are stemming from a set of requirements imposed on the MTJ performance: simultaneously low writing current/voltage and high thermal stability, high magneto-resistance at low RA (resistance and area product) value, low error rates and high endurance cycles. We will discuss the inter-dependencies of these parameters, and show how they are affected by varying magnetic properties of the MTJ stack layers. In particular, we study impact of the free layer anisotropy, magnetic moment, thickness, and Gilbert damping on writing current and thermal stability. In this presentation, we report our progress in meeting these requirements and our development approaches for future challenges.

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Mohamad Krounbi has over 25 years of experience in magnetic recording technology and recording head process and design innovations. While at IBM from 1978 to 1997, he played a leading role in the development and production of the magneto resistive heads from MR to GMR and TMR generations of products. Mohamad contributed to major breakthroughs in design, process, and integration of heads and media in the HDD industry. He held executive positions at IBM, Western Digital, and Hitachi Global Storage Technology (HGST). Mohamad holds over 50 US patents and co-authored numerous scientific publications in magnetic recording and fundamental materials and polymer research. He received numerous outstanding innovation and contribution awards while at IBM and was elected to the IBM academy of technology in 1995.  At HGST he was awarded the President’s technology award for the development and launch of the first perpendicular magnetic recording product.  In 2010, Mohamad joined Grandis, Inc. as the CTO and Senior Vice President of  technology development and operations.  Mohamad is currently the CTO and Senior Vice President of Samsung’s New Memory Technology Laboratory in the US ( NMT Lab).  Mohamad has a BS in Physics from Hagazian College in Beirut Lebanon and a MS in Physics from San Jose State University.
(Invited) Resistive Random Access Memory for Storage Class Applications
Authors: Jo Sung Hyun , Kumar Tanmay
Published: February 2020

Resistive RAM (RRAM) is one of the most promising emerging nonvolatile memory technologies thanks to fast operation, superior scalability, low power consumption and potential for 3D stacking. From an architectural point of view, 1T1R architecture is suitable for embedded memory applications while 1S1R based cross-point architecture is suited to high density memory applications. In the 1S1R based cross-point integration, however, the suppression of sneak current paths has been the major technical barrier for the high density RRAM.

We show that the sneak path challenge has been overcome by utilizing a Field Assisted Superlinear Threshold (FAST) selector [1]. The FAST selector device uses an insulating amorphous material which provides volatile switching at critical electric field. Excellent selector performance is presented, including high selectivity of > 107, sharp switching slope of < 5mV/dec., and large endurance of > 1011. The low fabrication temperature (≤300°C) of the FAST selector allows 3D stacking of 1S1R memory layers. It is also demonstrated that a volatile switch based selector has inherent benefits such as low voltage overhead for 1S1R integration and high read voltage margin.  

For the 1S1R demonstration, electrochemical metallization RRAM with a sub-5nm filament is utilized. The RRAM device offers a self-current-limiting feature during the program operation [2]. The self-limited program obviates the need for external current compliance, which can increase the number of concurrent programs in the 1S1R cross-point architecture with reduced power consumption and increased reliability benefits. Furthermore, the hold voltage property (snap-back behavior) of a FAST selector allows novel sensing techniques such as Resistance Ratio Amplification (RRA) which amplifies the intrinsic ON/OFF ratio of RRAM by a factor of > 104 [2]. Besides the direct advantage of increased memory ON/OFF ratio, the RRA technique also reduces BER and increases read bandwidth of the RRAM array. The integrated self-current-limited RRAM with FAST selector enables the high density and high performance 1S1R RRAM technology.

References

[1] S. H. Jo, T. Kumar, S. Narayanan, W. D. Lu and H. Nazarian, “3D-stackable crossbar resistive memory based on field assisted superlinear threshold (FAST) selector,” IEDM, 2014.

[2] S. H. Jo, T. Kumar, C. Zitlaw and H. Nazarian, “Self-limited RRAM with ON/OFF resistance ratio amplification,” VLSI Tech. Symp. 2015.

Figure 1
High Performing Semitransparent Graphene/BiFe0.95Si0.05O3/ITO Ferroelectric Photovoltaic Device
Authors: Gupta Surbhi , Katiyar Rajesh K. , Medwal Rohit , Pavunny Shojan P. , Limbu Tej B. , Tomar Monika , Morell G , Gupta Vinay , Katiyar Ram S.
Published: February 2020

Enriched and versatile room temperature multiferroic, BiFeO3 has been widely appreciated for future generation optoelectronic devices including light detectors, terahertz emitters, tunable solar cells, micro-sensors, and thin-film transistors with additional degree of magnetic and electric control. Moreover, literature also highlights its adjustable electrical, optical, and ferroelectric properties by doping with selected elements. We hereby report substantial photovoltaic response of semitransparent graphene/semiconductor Si doped BiFeO3 hetero-structure fabricated on In2O3 doped SnO2 coated glass substrates using bottom up spin coating technique considering the commercial aspect. The short circuit current density Jsc and open circuit voltage VOC were measured as 75 mA/cm2 and 0.45 V, respectively, with approximately 3 orders of increase in current density under standard AM1.5 (100 mW/cm2) illumination at room temperature. For the first time crystal structure, optical band gap, leakage behavior, ferroelectric and magnetic characteristics of 5 mol% Si doped BiFeO3 polycrystalline thin films is investigated and reported. Quick and reproducible transient response of JSC and VOC with (ton,toff  <100 ms) for more than 50 consecutive cycles establishes high scale of endurance and retentivity. Further, high stability (95%) of photo-response of chemically derived photovoltaic cell over a period of 16 weeks was achieved in ambient condition. This work establishes BiFe0.95Si0.05O3 as a high performing multiferroic material with complementary graphene and ITO as electrodes for self-powered oxide electronics.
Electrochemical Behavior of Silicon in Eutectic Calcium Chloride and Calcium Fluoride Molten Salt
Authors: Huang Wen-Hsi , Tao Meng
Published: February 2020

It is suggested that solar grade silicon can be produced by electrorefining of metallurgical grade silicon in a three-electrode cell. This study focuses on the electrochemical behavior of silicon in eutectic calcium chloride and calcium fluoride molten salt. The mixture of calcium chloride and calcium fluoride was heated to 750˚C as the electrolyte. Tungsten was used as the reference electrode and as the cathode, while silicon cut from a boron-doped silicon wafer with ~0.5 ohm-cm resistivity was used as the anode and cathode. Cyclic voltammetry was performed to reveal the voltages for silicon dissolution and deposition. It also illustrates the removal of dissolved silicon from the electrolyte. In addition, in-situ purification of the electrolyte is demonstrated.
Perovskite Based Solar Cells with Multi-Walled Carbon Nanotubes (MWCNTs)/Carbon Back Contact
Authors: Abdel-Fattah Tarek M , Ebrahim Shaker , Ramadan Wegdan , Nofal Mohammed , Soliman Moataz
Published: February 2020

The search for alternative energy solutions is currently a leading research area and will remain so for the foreseeable future, and photovoltaics (PV) are a key technology for a sustainable energy supply. The impressive properties of perovskites solar cells could ultimately boost efficiencies as close as commercial costly single-crystal silicon. That could make solar electricity as cheap as electricity produced from coal or natural gas. Solution base process of highly crystalline organic–inorganic hybrid perovskite CH3NH3PbI3-xClx pigment with promising visible-to-near-infrared absorptivity and electrical properties has attracted great attention to be used as a sensitizer for mesosuper structured solar cells.

In this work we fabricated cell structure of FTO/TiO2/ CH3NH3PbI3-xClx/ MWCNTs-carbon as shown below in the schematic diagram (Figure 1). TiO2 compact layer improved adhesion between the meso-TiO2 layer and FTO surface to facilitate electron transfer and enhanced the efficiency of the photoelectrical conversion. Multi-walled carbon nanotubes/carbon paste back contact was used with polymeric binder. The output cell parameters achieved from current-voltage curve (Figure 2) were open circuit voltage of 0.72 V, short circuit current density of  11.62 mA/cm2, fill factor of 0.27 and power conversion efficiency of 2.3%.

Figure 1