bluuebunny/crossref_metadata_2025 huggingface dataset:
Persistent Drought Monitoring Using a Microfluidic-Printed Electro-Mechanical Sensor of Stomata in Planta
Authors: Koman Volodymyr , Lew Tedrick , Wong Min Hao , Kwak Seon-Yeong , Giraldo Juan Pablo , Strano Michael S
Published: February 2020

Stomatal function can be used effectively to monitor plant hydraulics, photosensitivity, and gas exchange. Current approaches to measure single stomatal aperture, such as mold casting or fluorometric techniques, do not allow real time or persistent monitoring of the stomatal function over timescales relevant for long term plant physiological processes, including vegetative growth and abiotic stress. Herein, we utilize a nanoparticle-based conducting ink that preserves stomatal function to print a highly stable, electrical conductometric sensor actuated by the stomata pore itself, repeatedly and reversibly for over 1 week. This stomatal electro-mechanical pore size sensor (SEMPSS) allows for real-time tracking of the latency of single stomatal opening and closing times in planta, which we show vary from 7.0 ± 0.5 to 25.0 ± 0.5 min for the former and from 53.0 ± 0.5 to 45.0 ± 0.5 min for the latter in Spathiphyllum wallisii. These values are shown to correlate with the soil water potential and the onset of the wilting response, in quantitative agreement with a dynamic mathematical model of stomatal function. A single stoma of Spathiphyllum wallisii is shown to distinguish between incident light intensities (up to 12 mW cm−2) with temporal latency slow as 7.0 ± 0.5 min. Over a seven day period, the latency in opening and closing times are stable throughout the plant diurnal cycle and increase gradually with the onset of drought. The monitoring of stomatal function over long term timescales at single stoma level will improve our understanding of plant physiological responses to environmental factors.
A Sandwiched Immunosensor for Highly Selective and Sensitive Detection of Alpha-Fetoprotein By Using CdTe@SiO2/GO Electrochemiluminescence Probes
Authors: Pan Deng , Shen Yanfei
Published: February 2020

Alpha-fetoprotein (AFP), mainly synthesized in fetal liver, was a highly specific and heightened sensitive tumor marker for primary liver cancer. The increase of the AFP concentration in adult serum may be an early sign of some cancer diseases. Therefore, it is necessary to detect its concentration in clinical diagnosis to improve diagnostic accuracy and efficiency. Currently, many analytical techniques have been developed as a standard method for the determination of AFP, including Enzyme-linked immunoassay, time-resolved fluoroimmunoassay, surface plasmon resonance, atomic absorption spectroscopy, chemiluminescence fluorescence method, high-performance liquid chromatography (HPLC), and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS), which are sensitive and accurate. However, these methods typically require well-equipped laboratory facilities, time-consuming sample pretreatment and skilled operators, which significantly limit the applications for fast-screening of large amounts of practical samples. Herein, an ultrasensitive sandwich-type electrochemiluminescence (ECL) biosensor for the analysis of Alpha-fetoprotein (AFP) antigen was fabricated based on CdTe doped silica nanoparticles on graphene oxide (CdTe@SiO2/GO) nanocomposites as carrier to immobilize labeled AFP antibody and chitosan/multi-walled carbon nanotubes (CS/MWCNTs) composite as carrier to immobilize capture AFP antibody. In this project, capture antibodies were immobilized through covalent combination which could catch the target AFP protein as much as possible. High ECL signal could be obtained due to the luminant CdTe@SiO2/GO produced larges number of the emission photons. Because of its good conductivity and high surface area, the CS/MWCTs composite material, on the one hand, accelerated the electron transfer rate of electrode surface, on the other hand, it improved the loading rate of capture antibody and labeled antibody, thus further obtaining the high ECL intensity and improving the sensitivity of the sensor. In this strategy, under optimized conditions, the ECL intensity increased with the logarithmic values of AFP standard concentrations from 1.0 pg·mL-1 to 100 ng·mL-1 with a detection limit of 0.22 pg·mL-1 (at an S/N ratio of 3). The ECL immunosensor provided detection method with satisfactory recoveries, excellent reproducibility and stability, indicating that this method had a prospect in the practical application in the clinical diagnosis of AFP.

Figure 1
Impact of Bio-Recognition Element Density and Other Factors Impacting Impedance Sensor Performance
Authors: Brothers Michael , Nicolini Ariana , Chavez Jorge , Martin Jen , Grigsby Curt , Drummy Lawrence , Naik Rajesh , Kim Steve
Published: February 2020

Human performance monitoring ultimately requires integrating real-time data from both traditional physiological traits, such as body temperature, heart rate, and blood velocity and neurological biochemical molecular biomarkers to predict performance. While real-time monitoring of such physiological parameters are readily available using commercial off the shelf sensors, precise monitoring of biochemical biomarkers in real-time is still a challenging area.

Electrochemical impedance based sensors (EIS Sensors) have promise to provide detection of a wide array of molecular biomarkers of interest. The possibility to “plug and play”, the ability to integrate into a miniaturized format, and the potential to make reagentless sensors cause these sensors to be of high interest for performance monitoring. However, the self-assembled monolayer (SAM) containing the biorecognition element and issues that impact drift and noise are seldom investigated thoroughly.

The work presented here takes an in-depth look at packing density in the SAM and the effect on signal, as well as factors that may cause sensor drift. Through studying SAM density and drift, we are able to optimize signal and minimize noise, especially in highly sensitive sensors, even enabling detection of cortisol, a cognitive level biomarker of interest. Using both a proof-of-concept lysozyme aptamer, as well as a cortisol aptamer, we were able to observe the impact of packing density on sensor performance, and the consistency of these aptamers enabled through optimization of self-assembled monolayer (SAM) formation. With the results from the lysozyme SAM optimization, we followed a similar methodology to optimize the SAM for detection of cortisol. In order to broaden out the scope of this work, we used these finely tuned SAMs and performed a direct comparison of optimal and suboptimal SAMs on gated Field-Effect Transistor (FET) sensors as well.

We conclude that not only does SAM density result in an order of magnitude change in output signal, but that understanding and compensating for drift factors enable for reliable, consistent, reproducible sensors for implementation in a broad array of applications.
Design and Development of Electrochemical Analyzer for Detection of Δ9-Tetrahydrocannabinol (THC)
Authors: Karimi Anahita , Dweik Badawi
Published: February 2020

Δ9-Tetrahydrocannabinol (THC), the active substance in marijuana, is known to reduce psychomotor function and cognition thus greatly impairing driving ability. Existing THC detection technologies (urine or blood-based) are not adequate for assessing recent exposure to determine if a driver is operating under the influence. Giner describes a novel approach which involves the utilization of inexpensive disposable electrodes and electrochemical measurements to detect the presence and abundance of target THC molecules in saliva. Saliva testing via electrochemical detection will eliminate the need for expensive and time-consuming analytical techniques which have a turnaround time of several days.
Stretchable Sensors for Body-Attachable Wearable Electronics
Authors: Lee Nae-Eung
Published: February 2020

Wearable electronics is one of the promising approaches for smart healthcare in near future. Various sensor-integrated wearable systems including dressable, accessary-like, skin-attachable or implantable platforms can monitor vital signs, detect biomarkers for disease diagnostics, and monitor the patients with chronic diseases and can be also used to detect the hazardous environmental factors around human with unobtrusiveness and pervasiveness. In particular, various physical, chemical and biological sensors with new functionalities such as flexibility, stretchability, optical transparency and conformality as well as stability and reliability against mechanical deformations are promising for skin-attachable platforms. In this presentation, stretchable physical sensors (strain, pressure, and temperature), chemical sensors (gas) and biosensors (metabolite, protein) based on low-dimensional nanoscale materials (0D, 1D and 2D), nanocomposites and their hierarchical nanohybrids in FETs, resistors or three-electrode electrochemical sensors are presented for applications to skin-attachable patches. In addition, some examples of patchable integrated platforms with multiple sensors or sensor-energy harvester-energy storage for monitoring of physiological parameters, emotional expressions, bodily motions, and daily activities of human are also presented.
Conductive Shape Memory Gels for Sensing Application
Authors: Ahmed Kumkum , Shiblee MD Nahin Islam , Khosla Ajit , Furukawa Hidemitsu
Published: February 2020

Shape memory gels (SMGs) are one of the interesting and unique classes of soft and wet materials having wide application in actuator, sensor, optical and biomedical field. Thermal responsive SMGs have the ability to return from a temporary deformed state to its original shape under the influence of heat thus having the limitation of quick and proper control. On the other hand, conductive hydrogels have high potential in the field of medical treatment (drug release), electrochemistry (bioactive electrode coating), sensors and actuators. Our group has developed DMAAm-co-SA SMG with high mechanical strength, very good transparency and biocompatibility having potential application in different sectors [1]. Thus, we are motivated to combine the physical and mechanical properties of the SMGs with the electrical activity of an electroactive component in order to create unique prospects for the next generation materials. However, conductivity is not part of the inherent characteristics of the hydrogels, it can be provided by other materials or particles that are incorporated within the network of the hydrogels (e.g., conductive particles, conjugated polymers, etc.). Fully swollen hydrogels with conducting particles, such as graphite, carbon nanotubes or metallic particles incorporated in their structure typically show conductivity but conductivity is inversely affected by the swelling ratio, and the hydrogels exhibit brittle mechanical behavior [2]. In this work conductivity of the SMGs was achieved by chemically polymerizing EDOT (with PSS as the molecular dopant) within the tough SMGs fully swollen network. Here we could achieve conductive SMG with high swelling ratio and good mechanical toughness and studied their electric signal as a function of applied pressure or strain for application in sensor devices like pressure sensor or strain sensor.

References

[1] Amano, Y; Hidema, R; Gong, J; Furukawa, H. Chem Lett.,41, 1029-1031 (2012)

[2] Morita, S; Kawai, T; Yoshino, K. J. Appl. Phys., 69 (8), 4445−4447 (1991).
A Review of Electrochemical and Non-Electrochemical Approaches to Determining Oxide Concentration in Molten Fluoride Salts
Authors: Goh Bonita , Carotti Francesco , Scarlat Raluca Olga
Published: February 2020

The design of reactor core and heat transfer systems for molten salt reactors (MSRs) and fluoride-salt cooled high temperatures reactors (FHR) necessitates a precise understanding of the parameters affecting thermophysical and chemical properties of the molten salt medium. Oxides constitute a significant component of the impurities in alkali metal halide melts commonly implemented in MSRs. They are present initially in the raw materials due to the manufacturing process. If present in high enough concentrations, oxides can affect molten salt chemistry and thermodynamics, potentially affecting its thermophysical properties and corrosivity to structural materials. The dissolved oxide content in the melt can vary during reactor operation due to transmutation or migration to/from the environment. Therefore, it is important to develop capabilities to quantify the oxide concentration at reactor conditions. The benefit is threefold: firstly, measuring oxide concentration precisely and accurately will allow us to correlate oxide concentration with variation in thermophysical and chemical properties; secondly, knowing these correlations can facilitate the formulation of more incisive experiments to more accurately determine the activity of oxide in molten fluorides ; thirdly, such an oxide measurement system can be deployed online in a reactor as a sensor to add to the suite of reactor diagnostic instrumentation. These goals in concert will help us gain a better understanding of the basic science of a molten salt solvent environment.

In context of the ongoing effort to design an oxide sensor for molten salt systems, a review of the literature of electrochemical and non-electrochemical approaches to determining oxide concentration in molten fluoride salts was conducted and an evaluation of their merits is presented here. This evaluation served as the basis on which we selected square wave voltammetry as the most promising technique with which to develop an oxide sensor.
Magnetically Actuated Beating Cilia for Pre-Concentration of Bacteria
Authors: Hesketh Peter , Hanasoge Srinivas , Alexeev Alexander , Erickson Marilyn , Xu Jie
Published: February 2020

Detecting low concentrations of bacteria in food samples is a challenge. The pre-concentration and separation of the target bacteria from the food matrix can be enhanced using improved fluid handling. We have demonstrated a method for pre-concentration of bacteria from a liquid sample making use of arrays of artificial cilia. The cilia are defined using thin film processes on a glass substrate and are actuated magnetically with an external magnetic field. We demonstrate particle capture with cilia, by functionalizing the surface of the cilia with streptavidin protein and capturing biotin labelled particles on its surface. The functionalized cilia are incorporated inside a microchannel and biotin labelled particles are introduced into array of the cilia. The oscillating cilia are also capable of creating a net fluid flow which can be used for fluid pumping and mixing. We study the kinematics of the elastic cilia, with their asymmetric stroke, and demonstrate that it depends on two dimensionless numbers. To demonstrate pumping effects with arrays of cilia, we incorporate them on the inner walls of microchannel loop and measure the pumping rate while varying many of the parameters of the system. We report high pumping rates and characterize the fluid handling capability of such systems in terms of two dimensionless parameters.
(Invited) Nanoparticles Based Electrochemical Biosensors for the Detection of Tumor Cells and Associated Biomarkers
Authors: Zhu Jun-Jie
Published: February 2020

Recently, we have developed a series of robust, nanobiotechnology-based electrochemical biosensing approaches with high sensitivity, and reproducibility toward the simultaneous multiplex detection and classification of both acute myeloid leukemia and acute lymphocytic leukemia cells, quantitative evaluation of DR4/DR5 expression on leukemia cell surface, dual-channel detection of matrixmetalloproteinase-2 (MMP-2) in human serum as well as ultrasensitive circulating tumor cells (CTCs) electrochemical cytosensing using Fe3O4@AuPd nanocages as the nonenzymatic nanoelectrocatalysts . Self-powered biosensor based on enzyme biofuel cell (EBFC) was another kind of super-sensitive self-contained sensing system which was powered by EBFC, meanwhile, the output of EBFC was directly related to the analyte concentration. The system was capable of detecting cancer cells, quantifying two types of cancer-related biomarkers (miR-21 and miR-141). Furthermore, we have developed a self-powered cascading integrated system for tumor diagnosis, therapy, and prognosis supervision. These versatile electrochemical biosensing platforms hold great promise as new point-of-care diagnostic tools for early detections and are believed to be of great clinical value for the evaluation of therapeutic effects on patients after radiation therapy or drug treatment, moreover, provide potential opportunity for developing economical preclinical theranostic platform.
Fabrication of 3D Nanocarbon Structure for Potential Sensor Applications
Authors: Senegor Richard , Baron Zack , Luo Dayou , Shaffer Julia , Michelmore Andrew , Yang Cary Y
Published: February 2020

An all-carbon 3D nanocarbon structure has been designed and fabricated using carbon nanotubes (CNT) grown on multi-layer graphene (MLG). This work was motivated by the need of current integrated circuit (IC) technology to eventually replace copper (Cu) and tungsten (W) as interconnect materials. Such a structure can also potentially be part of a chemical or biological sensing system.

Our experimental process consists of using a plasma-enhanced chemical vapor deposition (PECVD) process to grow CNT arrays directly on an MLG-covered silicon substrate after sputtering a thin nickel, iron, or cobalt (Co) catalyst film. The fabricated devices are evaluated and characterized through a combination of scanning electron microscopy and electrical measurements using a nanoprober.

The PECVD process results in highly aligned but non-conductive CNT/Graphene structures due to damages in the graphene film during CNT growth. To mitigate this challenge, we successfully identified the source for graphene damage as the plasma in the CNT growth process and, as a result, replaced PECVD with a thermal CVD growth process.

The resulting CNT/Graphene devices fabricated using Co as catalyst are conductive, with an estimated CNT-graphene contact resistance of 1.4 kΩ. Thus, we have taken the first step in demonstrating electrical conduction through an all-carbon, 3D nanostructure fabricated by growing CNTs directly on graphene.

Further experimentation is currently underway to verify and improve upon our process, including in situ nanoprobing to fully characterize the electrical properties of these devices. In addition, we use a combination of transmission electron microscopy and electron energy loss spectroscopy to verify a homogenous interface between the CNT and MLG by demonstrating the continuation of C-C sp2 bonding. Independently, we are investigating the compatibility of our current process with other CNT growth catalysts. To achieve effective sensing, additional improvements are needed, such as vertical CNT alignment, high CNT areal density, and small average CNT diameter.
Cobalt-Based Oxygen Evolution Electrocatalysts Biotemplated on DOPA-Displaying Viruses
Authors: Rho Jihun , Chung Taek Dong
Published: February 2020

The Oxygen evolution reaction (OER), which involves a more complex mechanism compared to hydrogen evolution reaction (HER), determines the whole cell efficiency for (photo)electrochemical water splitting. Lately, non-precious metal based oxygen evolution catalysts (OECs), such as transition metal oxides got attentions for OER under relatively benign conditions at low overpotentials. In this work, we report a filamentous bacteriophage fd displaying 3,4-dihydroxy-L-phenylanlanine (DOPA) onto the major coat protein and promoted the spontaneous deposition of cobalt oxide based oxygen evolution catalyst (Co-OEC) onto the phages. The virus successfully worked as a biotemplate to enable deposition of thin Co layer along wire-like bodies, and the catechol group of DOPA moiety stabilized Co2+ to accelerate Co-OEC deposition on virus and slightly enhanced OER activity. The Co-based catalysts adhered to DOPA-phages through electroless deposition (Co/DOPA-phages) showed cathodic shift of Co3+/2+ oxidation peak and this phenomenon could be explained from partial-charge transfer from cobalt to DOPA group, which is supported from X-ray photoelectron spectroscopy (XPS) that shows more distinct satellite peaks of Co2+ at ~786 eV compared to electrodeposited Co-OEC. It is widely accepted that partial charge transfer caused by dopant cations raise activity enhancement and change the OER mechanism. The pronounced OER activity under 10 mA cm-2 and long-term stability of Co/DOPA-phages suggest potential for further optimization via systematically ordered and denser array of catechol group for improved performance.
Design of a Biomimetic Hydrogel Nanocomposite Material for Responsive Wound Management
Authors: Lange Heather R. , Werth Lauren K. , Chura William E. , Keleher Jason J.
Published: February 2020

Current wound management technology can inhibit the healing process due to poor adhesion to the wound surface, low uptake of exudate, and lack of inherent antimicrobial properties. Alternatives to traditional wound dressings include hydrogels, which are supramolecular matrices, stabilized by non-covalent interactions that absorb large amounts of fluid and exhibit flexible behavior. This research uses an amino acid-calcium complex to crosslink an alginate hydrogel which is further functionalized with metal (Ag, Au) nanoparticles. Previous research has shown that amino acids such as tryptophan and serine have increased the non-covalent interactions within the network, resulting in greater gel strength. The hydrodynamic radius and structural diversity of the amino acid has also been shown to exhibit an inverse relationship between the gels ability to swell and its tensile strength. To harness the porosity and swelling capacity of the hydrogel, conductive polymers polyaniline (PANI) or polypyrrole (PPy) can be layered onto the biomimetic hydrogel to yield a responsive wound dressing. As wound secretions diffuse through the hydrogel and into the electroactive layer, the conductivity of the matrix increases and induces an electrochemical signal. The efficacy of the composite is characterized by simultaneously measuring swellability and the increase in conductivity, indicating the point of saturation. Initial results showed that after 150 minutes in a simulated wound environment, the composite swelled upwards of 150% and increased in conductivity up to 20%.
Enhancement of Conductive Coated Polymer Networks Utilizing Guest-Host Inclusion Complexes for the Electrotreatment of Heavy Metal Ion Effluent
Authors: Lanasky Katelyn Patricia , Lambert Joseph Edward , Keleher Jason J.
Published: February 2020

As water pollution continues to be a global concern, there is a demand for cost effective remediation technologies. A large contribution of water scarcity can be traced back to heavy metal ion contamination which current technologies, such as ion exchange or ‘softening’ have proven to be ineffective. This work focuses on the remediation of heavy metal ion pollutants using the incorporation of β-Cyclodextrin (β-CD), and conductive polymers into an adsorbent, cellulosic nanocomposite. Previous results have shown that β-CD can enhance the adsorption capability allowing the removal of 75% Cadmium (Cd) ions from solution. To further increase the yield of metal ion removal, the chemical polymerization of a conductive polymer, such as polyaniline (PANI) introduces electrochemical properties to the cellulosic film. Initial results have indicated that with the application of voltage these conductive nanocomposites have the ability to be used for the electrochemical treatment of simulated wastewater as Copper (Cu) ions were shown to be successfully removed from solution.
Lanthanum Nickelate Cathode Materials for Intermediate Temperature-Solid Oxide Fuel Cells
Authors: Lee John In , Park Ka-Young , Park Jun-Young
Published: February 2020

Solid oxide fuel cells (SOFCs) have been considered as the next-generation energy conversion electrochemical devices that can transform chemical energy of fuel to electrical energy. In particular, various advantages of SOFCs, such as high energy conversion efficiency, negligible pollutant emission, and the multi-fuel capability, make them indispensable for the renewable society [1].

The rate determining step of energy conversion in state-of-art SOFCs at intermediate temperature (IT) is the sluggish kinetics of oxygen reduction reaction (ORR) in the cathode, and thus the cathode material significantly affects performances of IT-SOFCs. Up to now, cobalt-based perovskite oxides have received great attentions for the cathode material because of the low overpotential for ORR. [2]. However, cobalt-based materials have significantly high thermal expansion coefficient (TEC) values ( ), compared to those of typical electrolytes (yttria-stabilized zirconia and rare-earth-doped ceria, ). This big discrepancy gives rise to mechanical stress to the cell, which affects the long-term stability of cells [3]. Furthermore, cobalt-based materials are expensive and have a low stability under reducing atmospheres. In contrast, the TEC of lanthanum nickelates (Lan+1NinO3n+1) is , which is nearly analogous to the TEC of electrolyte materials [4]. In addition, lanthanum nickelates have high electrical conductivity with the great stability at IT. In this work, the performance and durability of lanthanum nickelates are investigated in the anode-supported cell design and analyzed by using various tools such as TEM, XPS, and DFT calculations [5].

References

[1] K.T. Lee, E.D. Wachsman, Science 334 (2011) 935.

[2] W. Zhou, Z. Shao, J. Power Sources 192 (2009) 231

[3] S. Pang, X. Xi, J. Power Sources 326 (2016) 176.

[4] R.K. Sharma, E. Djurado, J. Power Sources 325 (2016) 337.

[5] T.H Lee, J.-Y. Park. J. Power Sources 331 (2016) 495

Keywords: Solid oxide fuel cells; Lanthanum nickelate; Thermal Expansion Coefficient; Conductivity, Stability
Bifunctional Non-Noble Transition Metal Oxide-Based Materials for Unitized Reversible Fuel Cells
Authors: Choi Sung Ryul , Afzal Rana Arslan , Park Jun-Young
Published: February 2020

Because of the emerging global warming and environmental pollutions, hydrogen as a renewable and sustainable energy source has expected to solve those global issues [1]. In particular, hydrogen-fueled fuel cells are one of the most promising electrochemical energy conversion devices due to their high efficiency and negligible pollution emissions. Furthermore, URFCs that produce both hydrogen fuel and electricity in one single device have received great attentions these days. However, URFCs have several technical barriers for making commercialization, such as sluggish catalytic kinetics of oxygen reduction (ORR) and oxygen evolution reactions (OER) [2]. Up to now, noble metal (e.g Pt/C and IrO2)-based electrocatalysts have still used to get high performances of OER and ORR, even though these metals have critical drawbacks such as expensive price and low durability [3]. In order to overcome these problems, many transition metal oxide-based materials have studied as bifunctional electrocatalysts [4, 5]. In this work, in order to improve electrocatalytic activity of transition metal oxide-based catalysts, high surface area carbon-based supporting materials such as graphene or carbon nanofiber are considered [6]. The graphene-carbon nanofiber-suppported transition oxide catalysts are synthesized by the hydrothermal method and analyzed by various physicochemical and electrochemcial tools [7].

References

Landon, E. Demeter, N. İnoğlu, C. Keturakis, I. E. Wachs, R. Vasić, A. I. Frenkel, and J. R. Kitchin, ACS. Catal.,
8, 1793 (2012).

K. Fominykh, P. Chernev, I. Zaharieva, J. Sicklinger, G. Stefanic, M. Döblinger, A. Müller, A. Pokharel, S. Böcklein, C. Scheu, T. Bein, and D. Fattakhova-Rohlfing, ACS. Nano., 5, 5180 (2015).

M.W. Louie, and A.T. Bell, J. Am. Chem. Soc., 33, 12329 (2013).

A. C. Pebley, E. Decolvenaere, T. M. Pollock, and M. J. Gordon, Nanoscale., 9, 15070 (2017).

Y.-F. Li, and A. Selloni, ACS Catal., 4, 1148 (2014).

I.-S. So, N.-I. Kim, S.-H. Cho, Y.-R. Kim, J. Yoo, Y. Seo, Y.-S. Seo, B. Park, K. Kwon, and J.-Y. Park, J. Electrochem. Soc., 163, F3041 (2016).

N.-I. Kim, Y.J. Sa, S.-H. Cho, I. So, K. Kwon, S.H. Joo, and J.-Y. Park, J. Electrochem. Soc., 163, F3020 (2016).
Electrolyte Effects on Shewanella Oneidensis MR-1 Loading and Cyclic Voltammetric Behavior at an ITO Electrode
Authors: Alshahrani Aisha Awad
Published: February 2020

The goal of this study is understanding phenomena which may help design electrode modifications enhancing efficiency of microbial fuel cells. Our hypothesis is that the rate of deposition is proportional to both composition of the outer cell membrane and the bulk concentration. We also suggest that ionic strength and ion identity can affect the efficiency of sticking after initial encounter. Shown here are electrochemical studies on effect of salt concentration on S. oneidensis MR-1 attachment and growth at ITO electrodes. Initial surface coverage of bacteria can be measured with respect to four metric. One metric is the observed lag time before currents increase during bacterial loading at the ITO surface. A second one is the current associated with that lag time. The third is the maximum anodic current that occurs after the lag period. Finally a cyclic voltammetric experiment following loading has a metric associated with the cathodic peak current. The peak current is very large for NaCl compare to CsCl. The final coverage (as measured by cathodic peak current in cyclic voltammetry, ipc) increases with increasing ionic strength (IS). We suggest that the behavior of cathodic peak current is very sensitive to the salt concentrations and bacteria harvest time. Our results clearly show a major difference in attachment and behavior of S. oneidensis MR-1 for NaCl compared to CsCl. CsCl inhibits all four metrics associated with loading at +0.2 vs Ag/AgCl (lag time, lag current, maximum loading current and cyclic voltammetric peak current).
Integration of Porous Piezoelectric Separator for a Self-Charging Supercapacitor
Authors: Li Mengping , Hwang Jee Youn , El-kady Maher , McVerry Brian , Kaner Richard B.
Published: February 2020

Due to the miniaturization in the electronics industry, there has been an increasing demand for reliable portable power sources. Among all the power systems, self-charging power units composed of piezoelectric materials and energy storage devices attract a lot of scientists’ attention due to their ability to convert and store human biomechanical energy. Although piezoelectric materials with good performance are used as the separator for the power units, there is not much effort to improve the electrochemical performance of the energy-storage part. Nonporous piezoelectric films without pore structure are utilized, hindering the ion diffusion process in the cell, resulting in poor cell performance. In this work, we used metal oxide nanoparticles as the sacrifice template to fabricate porous piezoelectric film for application of supercapacitor separators. Thanks to the well-designed pore structure and pore volume, the film shows a dramatic decrease in ion diffusion resistance compared to a nonporous film while retaining its good piezoelectric properties. Due to the interconnected pore structure, the performance of our separator is even comparable to a commercialized polyethylene (PE) separator. With conducting polymer as the electrode material and polyvinyl alcohol (PVA)/H2SO4 as the gel electrolyte, the self-charging power unit is able to go over 0.2 V by palm pressing.
Spontaneous Formation of Pb/Ag Super Lattices
Authors: Owhoso Fiki V , Wu Dongjun , Brankovic Stanko
Published: February 2020

The aim of this project is to study spontaneous formation of Pb/Ag super lattices during potentiostatic electrodeposition process of Ag using Pb underpotentially deposited (UPD) monolayer serving as surfactant. The techniques used to study this process are cyclic voltammetry and chronoamperometry. In this study we use a 3-electrode electrochemical cell and BAS potentiostat CV 27. The working electrode is a single crystal Au(111) which is held in a hanging meniscus configuration. Reference and counter electrodes are Ag or Pb wires and Pt wire respectively. Our results suggest that current spikes recorded during potentiostatic deposition of Ag on Au(111) correspond to instant formation of Pb monolayer on top of a new formed Ag nucleus.
Vanadium Pentoxide Nanofibers as IR sensors for Bolometer Application
Authors: Paul Nirupam , Vadnala Sudharshan , Panigrahi Asisa Kumar , Kumar Hemanth , Agrawal Amit , Singh Shiv Govind
Published: February 2020

The main aim of this work is to report an alternative technique of creating vanadium pentoxide (V2O5) based uncooled infrared (IR) detector, by a state-of-the-art V2O5 nanofibers, manufactured by facile and economical electrospinning process. The nanofibers were thermally and electrically characterized to determine their bolometric performance. The nanofibers show maximum voltage responsivity of (ℜv ) 6987.3 V/W at 100 mA DC bias, under normal room temperature and pressure condition. Nanofibers show very good thermal response (τs ) and recovery time (τr ) when subjected to a periodic On-Off cycle of IR lamp (150W) illumination. Temperature dependent resistance measurement reveals that nanofibers are exhibiting semiconductor to metallic phase transition at 67°C with maximum TCR% -1.6%/K at the transition temperature. V2O5 nanofibers characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman Spectroscopy confirms their crystallinity and elemental composition. The optical band gap of the nanofibers is analyzed by UV-Visible spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images confirms their microstructural dimensions and surface homogeneity. The entire analysis reaffirms the suitability of V2O5 nanofibers as one of the futuristic sensing material for IR imaging applications.

Figure 1
Annealing Effects on the Electrical and Optical Properties of CaCu3Ti4O12 Thin Films
Authors: Skaria Giji , Sundaram Kalpathy B
Published: February 2020

There is an increased interest in very high dielectric constant (high-k) material studies due to their potential applications in energy storage elements. In this aspect, the perovskite materials seem to achieve very high-k values [1]. In this study, the focus has been to deposit thin films of CaCu3Ti4O12. These films are deposited by RF magnetron sputtering process using CaCu3Ti4O12 target. The films are deposited in an argon ambient and subsequently annealed in oxygen to investigate the electrical and optical properties. The studies include resistivity, dielectric constant and the band gap of the annealed films. Metal–insulator–metal (MIM) structures have been fabricated using aluminum film as the electrodes to study the electrical properties. The transmission and reflection properties are performed using the UV-Visible spectrophotometer to extract the bandgap of these annealed films.

REFERENCE:

[1] M.A. Subramanian, Dong Li, N. Duan, B.A. Reisner, A.W. Sleight, High Dielectric Constant in ACu3 Ti4 O12 and ACu3 Ti3 FeO12 Phases
Core-Shell V2O5/Conductive Polymers Hybrid Aerogels for High-Performance Supercapacitors
Authors: Bi Wenchao , Gao Guohua , Wu Guangming , Cao Guozhong
Published: February 2020

Vanadium pentoxide (V2O5) is a promising electrode material for supercapacitors owing to its high theoretical capacitance, natural abundance and low cost. However, the low conductivity and electrochemical instability hinder its practical applications. Subjected to this challenge, core-shell structured V2O5/conducting polymers hybrid aerogels, V2O5/Poly(3,4-ethylenedioxythiophene (PEDOT), V2O5/Polyaniline and V2O5/polypyrrole, were synthesized in a versatile varient vaper-phase polymerization process and the resulting samples exhibited the enhanced electrochemical performances. Especially, V2O5/PEDOT aerogels delivered a high specific capacitiance of 614 F g–1 and energy density of 85.3 W h/kg at the power density of 250 W/kg. After 50,000 cycles, V2O5/PEDOT presented a capacitance retention of 122% that suggests a capacity increase in the cycles. The excellent performances can be attributed to the robust conducting-polymer shell and valence varitation in V2O5. This effective stratagy pave a way to develop the high-performance electrode materials for supercapacitors.
High Performance Low Temperature Solid Oxide Fuel Cells with Alkali Metal Carbonate Additives in Co-Doped Ceria Electrolyte
Authors: Khan Ieeba , Basu Suddhasatwa
Published: February 2020

Doped ceria-carbonates composites are a new class of electrolytes for low temperature solid oxide fuel cells, these show very high ionic conductivity due to fast interfacial transport [1-2]. As reported by Chockalingum and Basu [3], 25 wt% (LiNa)2CO3-GDC electrolyte exibited an ionic conductivity of 0.17 S cm−1 at 550 °C and lowest activation energy of 0.127 eV in the temperature range 550–800 °C. To further improve the ionic conductivity, a series of calcium gadolinium/neodymium/samarium co-doped cerium oxide, M0.2CaxCe0.8-xO2 (x = 0.01 to x = 0.1) (M= Gd, Nd, Sm) have been synthesised by solgel method. The electrolytes have been physically and electrochemically characterized with respect to their thermal behaviour, phase, microstructure, elemental analysis and electrochemical performance using thermogravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy, Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy and electrochemical impedance spectroscopy respectively. The particle size of as synthesized electrolyte powders is ~ 20 nm as observed from the TEM. XRD results of the prepared electrolytes show that the powders are phase pure. The gadolinium calcium co-doped ceria lithium sodium carbonate (25% (LiNa)2CO3-Gd0.2Ca0.05Ce0.75O2) composite electrolytes exhibit high ionic conductivity (0.3 Scm-1 at 650°C), as it combines both the advantages of co-doping and the composite effect. Co-doped composite electrolytes show higher conductivity and stability due to the presence of calcium than the previously investigated composite electrolytes of (LiNa)2CO3-GDC [4, 5].

References

[1] L. Fan, C. Wang, M. Chen, B. Zhu, J. of Power Sources, 234, 154 (2013).

[2] R. Raza, H. Qin, L. Fan, K. Takerda, M. Mizuhata, B. Zhu, J. of Power Sources, 201, 121 (2012).

[3] R. Chockalingam and S. Basu, J. Hydrogen Energ., 36,14977 (2011).

[4] I. Khan, M.I. Asghar, P.D. Lund, S. Basu, J. Hydrogen Energ., Volume 42, 20904 (2017).

[5] I. Khan, P.K. Tiwari, S. Basu, S. Ionics (2017), doi.org/10.1007/s11581-017-2184-9.

Figure 1
Carbon Nanotubes - the p-Type Contact of the Future for Perovskite Solar Cells?
Authors: Habisreutinger Severin N. , Noel Nakita K. , Snaith Henry J. , Nicholas Robin J.
Published: February 2020

The enormous strides researchers have made in advancing perovskite based photovoltaics in the past few years are fueling the dream of a rapid entry of this highly promising technology into the global energy market. This seems like serendipitous timing since solar power has gained an enormous momentum over the past decade exceeding all projections. This expansion in solar power is driven by an increasing understanding that climate change requires immediate action, in particular with regards to power generation; and simultaneously, the price for photovoltaic modules has remarkably quickly fallen to make solar power generation competitive vis-à-vis conventional technologies.

Compositional tuning of the perovskite absorber has led to immense improvements in stability and efficiency of perovskite solar cells leading to a certified efficiency of 22.7% for a single-junction laboratory device. The successful transition of a photovoltaic technology from the lab into the field requires, however, two additional important parameters aside from efficiency which are essential for real-world deployment: stability and scalability.

We propose using single-walled carbon nanotubes (SWCNTs) as p-type layer for perovskite solar cells for future applications.

Carbon nanotubes combine several highly attractive characteristics such as chemical inertness and mechanical resilience with intrinsically high charge-carrier mobilities endowing them with a unique potential to be a very stable dopant-free charge-selective contact. Furthermore, the SWCNT deposition techniques for large-scale use, such as spray-coating, are already well-established, opening clear avenues for direct implementation in a real-world industrial setting.

In this study, we demonstrate that employing SWCNTs as hole-transporting material can yield steady-state efficiencies of above 20% for alloyed narrow bandgap perovskites, and of over 7% for wide-bandgap perovskites, illustrating the versatility and excellent performance of SWCNTs as charge-selective contact material.
(Invited) Genesis, Status, and Future of the Carbon Nanotube Optical Rectenna
Authors: Cola Baratunde
Published: February 2020

It has been nearly 50 years since the idea of an optical rectenna – a device that directly converts free-propagating electromagnetic waves at optical frequencies to direct current – was proposed. Many researchers have worked to realize this idea and overcome the major challenge: coupling an efficient optical antenna to a fast, low-resistance diode. In 2015, we demonstrated for the first time that this challenge could be overcome using carbon nanotubes (CNTs). A metal-insulator-metal diode fabricated at the tip of a vertically aligned CNT has a capacitance on the order of aF and rectifies visible, IR, and solar light into direct current. I will discuss the genesis of this result and the fundamental physics that makes it work. I will highlight results from my group’s current work where we have improved practical device function and increased conversion efficiency substantially in the last 2 years. I will conclude by highlighting remaining challenges and suggesting promising directions for future research.
High Performance Optical Rectenna Arrays Using Multiwall Carbon Nanotube–Insulator–Metal Tunneling Diodes
Authors: Anderson Erik C. , Bougher Thomas L. , Cola Baratunde
Published: February 2020

We report important fundamental advancements in multiwall carbon nanotube (MWCNT) rectenna devices, which have potential applications for infrared and terahertz sensing and energy harvesting. Our rectenna devices incorporate ultrafast metal-insulator-metal tunneling diodes fabricated on the tips of MWCNT antennas arrays to convert high-frequency electromagnetic waves to D.C. electricity. The tunneling barrier geometry and insulator material selection are critical to designing high performance MWCNT diodes. We demonstrate new MWCNT diode structures that incorporate multiple insulating layers to control electron tunneling and achieve excellent current-voltage asymmetry (>20) with air stable metal contacts (Al and Ag). For improving antenna-diode impedance matching, we demonstrate that reducing insulator thickness and etching open the MWCNT tips can lower resistance. Our double-insulator devices show the first evidence of air stable rectification under IR and visible laser illumination (Figure 1). Open-circuit voltage is several orders of magnitude higher than previous reports that utilized single-insulator MWCNT diodes, thereby making our double-insulator MWCNT rectenna devices especially attractive for infrared photodetectors. These results bring to light a new generation of MWCNT rectenna arrays that can use a variety of top electrode materials – including air stable, transparent, and conductive materials – indicating strong potential and efficient utilization in a variety of high-frequency applications.

Figure 1
(Invited) From Thermopower Waves to Asymmetric Chemical Doping – New Concepts in Energy Storage and Generation Using Molecular Interactions with Single-Walled Carbon Nanotubes
Authors: Liu Albert Tianxiang , Strano Michael S , Kunai Yuichiro , Liu Pingwei , Cottrill Anton
Published: February 2020

There is a pressing need to find alternatives to conventional energy generation techniques, specifically those that rely on elements in finite global supply. Thermopower wave (TPW) devices, which convert chemical to electrical energy by means of self-propagating reaction waves guided along nanostructured thermal conduits, have the potential to address this demand.1 We show that conversion efficiency can be increased significantly by selecting molecules such as sodium azide or sucrose with potassium nitrate to offset the inherent penalty in chemical potential imposed by strongly p-doping chemicals,2 a validation of the predictions of Excess Thermopower theory.3 Such chemical-potential-gradient-induced-electricity can be further exploited in a more direct manner, decoupled completely from the combustion reactions, affording another novel energy generation scheme using only molecular interactions, and subsequent charge transfers, with single-walled carbon nanotubes.4 Specifically, we demonstrate that chemically-modified carbon nanotube fibers enable unique power sources driven entirely by a chemical potential gradient.5 Short circuit electrical current (11.9 μA mg−1) and open circuit potential (525 mV) are reversibly produced by localized acetonitrile doping under ambient conditions. An inverse length-scaling of the maximum power as L−1.03 that creates specific powers as large as 30.0 kW kg−1 highlights the potential for microscale energy generation.

(1) Choi, W.; Strano, M. S. et. al. Nat Mater
2010, 9.

(2) Mahajan, S. G.; Liu, A. T.; Strano, M. S. et. al. Energy & Environmental Science
2016, 9, 1290.

(3) Abrahamson, J. T.; Strano, M. S. et. al. ACS Nano
2013, 7, 6533.

(4) Kunai, Y.; Liu, A. T.; Strano, M. S. et. al. J. Am. Chem. Soc.
2017, 139, 15328.

(5) Liu, A. T.; Kunai, Y.; Strano, M. S. et. al. Adv. Mater.
2016, 28, 9752.
Nitrogen Doped Graphene-Carbon Nanotubes and Nitrogen Doped Nano-Onion Hybrids As High-Performance Catalysts for Oxygen Reduction Reaction
Authors: Choi Eun Yeob , Kim Mu Hyeon , Kim Chang Keun
Published: February 2020

A nitrogen doped nanoonion and nitrogen doped graphene-carbon nanotube hybrid (NNO/NG-NCNT) was prepared as a non-precious electrocatalytic material for oxygen reduction reaction (ORR). The nitrogen doped nanooion (NNO) is a new promising carbon-based catalytic material, and its electrocatalytic activity toward ORR was further improved by mixing with nitrogen doped graphene-CNT (NG-NCNT). This improvement was achieved through the formation of hybrid structure, because the NG-NCNT weakened aggregation of the NNO by working as spacers. The formation of the NNO/NG-NCNT was characterized by Raman spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The ORR performance of the NNO/NG-NCNT was studied using rotating disk electrode (RDE) measurement. The RDE results indicated that the NNO had higher ORR activity than that of NG/NCNT, and the NNO/NG-NCNT showed superior ORR performance which was comparable to that of the platinum-based catalyst. In addition, the NNO/NG-NCNT has excellent long-term durability and tolerance to methanol crossover effect. Thus, the high electrocatalytic activity and good stability of the NNO/NG-NCNT make its potential applications as a metal-free catalyst for ORR.