bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metal Oxides Hetrostructure: An Efficient to NO2 Gas Detection
Authors: Patil Vikas B 
Published: May 2020

A global environmental pollution has become serious problem, due to extensive automobile density and industrialization deeds where destructive as well as poisonous gases like hydrocarbons, carbon monoxide and nitrogen oxides in the surrounding are being extremely used. Nitrogen dioxide (NO2) gas is a usual contaminant in air, in general formed through the power plants, combustion in industrial factories and automotive engines etc. As per health and safety guidelines concern human should not be in contact to 3 ppm exposure of NO2 gas for the time more than 8 hr as its poisonous character can consequence into deterioration and olfactory paralysis. Thus, it is essential to develop sensitive, cost-effective, selective, and trustworthy sensor for the finding of extremely crouch concentration of poisonous NO2 gas.
A metal oxide semiconductors (MOS) such as zinc oxide (ZnO), copper oxide (CuO), tungsten oxide (WO3), iron oxide (Fe2O3), tin dioxide (SnO2), Nickel oxide (NiO) and chromium oxide (Cr2O3) etc., have been widely addressed as sensor resources for NO2 gas due to their high sensitivity, reproducible and stability in idiom of gas response. Conversely; MOS gas sensors normally have their difficulty in disgraceful selectivity, nevertheless; change in resistance of the sensor caused by gas species, which assembles it unachievable for a sensor to precisely identify the gas molecules. Such selectivity and other central gas sensing recital of chemiresistive type MOS gas sensors can be enhanced through the amalgamation of metal oxide semiconductors. Spaced out from the MOS p-type CuO and n-type ZnO are immensely concerned in gas sensing assert due to their effortless synthesis, tailorable electrochemical properties, cost-effectiveness and eco-friendly signature too.
Here, a CuO nanoparticle (NPs) - ZnO nanowire (NWs) hetro-structure gas sensors have been developed by easy, catalyst free thermal evaporation (TE) technique, followed by annealing in different atmosphere such as argon and air. The crystal structural, surface morphological and gas sensing measurements of hetrostructure sensors were studied and reported. At optimized temperature of 150 °C, the hetero-structure sensors express a superior response up to 175% to concentration of 100 ppm NO2 gas. As synthesized hetro-structure sensors, responds to an enormously squat (1 ppm) disclosure of NO2 gas.

Figure 1
(Invited) Trace Level Detections By Surface-Enhanced Raman Scattering
Authors: Zhang Zhengjun 
Published: May 2020

The Raman signals of molecules attached on the very surface of noble metals nanostructures can be greatly enhanced due to the enhancement of the local electric field, by the localized surface plasmon resonance of the nanostructures incident by the laser beam. Therefore, one can make Raman scattering a powerful means in recognizing and quantifying molecules at trace levels. This, however, relies on the sensitivity, stability, etc., of the nanostructures which are used as the substrate surface-enhanced Raman scattering (SERS), and also, the methodologies to quantify the molecules, which are quite difficult even for normal Raman scattering.
We report here, our attempts to design and fabricate silver nano rods as substrate for surface-enhanced Raman scattering, with very high sensitivity, thermal and chemical stability, excellent reusability, etc., by glancing angle deposition techniques with an e-bam system, and covering the surface of the silver nano rods completely by atomic layers deposition of Al2O3 with a thickness of ~ 1.0 nm. These nanorods could be thermally stable in morphology and performance as the SERS substrates up to higher than 400 oC, and chemically stable in harsh environments. These makes the covered Ag nanorods applicable in real environments as SERS substrates. based on the principle component analysis (PCA), we also developed qualitative and quantitative analysis methodologies to quantify chemicals or molecules in complex systems even at trace levels by SERS. Several examples will be shown for trace level analysis of real samples by surface-enahnced Raman scattering with the substrates we designed and fabricated and the approaches we established.
Fast Screening of Pesticides By Raman Spectroelectrochemistry Based on EC-SERS Effect
Authors: Fanjul Pablo , Ibáñez David , Junquera-Pérez Alejandro , González-García María Begoña , Hernández-Santos David 
Published: May 2020

Electrochemical Surface-enhanced Raman spectroscopy (EC-SERS) effect is an outstanding procedure that ensures the enhancement of Raman signal, a careful control of the nanostructures prepared and the possibility of detecting different analytes while the substrate preparation is taking place. Development of novel EC-SERS procedures provide these benefits in the simultaneous preparation and measurement process [1,2], and open new gates for analytical applications. Activation of metallic screen-printed electrodes (SPEs) by electrochemical routes leads to the generation of reproducible nanostructures with excellent SERS properties. In that way, gold, silver and copper SPEs circumvent the traditional reproducibility limitation and produce the enhancement of the Raman intensity to favor the detection of low concentrations.
In this work, detection of different pesticides was achieved by the development of new electrochemical activation procedures using metallic SPEs as SERS substrates (Figure 1). The obtained results demonstrate that Raman spectroelectrochemistry is a powerful technique for monitoring the levels of pesticides, being this study the previous step in their detection in real samples.
Figure 1. Raman spectrum of thiram obtained during a cyclic voltammetry using Ag SPE.

References

[1] D. Martín-Yerga, A. Junquera-Pérez, M. B. González-García, J. V. Perales-Rondon, A. Heras, A. Colina, D. Hernández-Santos, P. Fanjul-Bolado, Electrochim. Acta 264 (2018) 183-190.
[2] D. Ibáñez, A. Junquera-Pérez, M. B. González-García, D. Hernández-Santos, P. Fanjul-Bolado, Talanta 206 (2020) 120190.

Figure 1
Ceramic Additive Manufacturing for the Rapid Prototyping of Mixed Potential Electrochemical Sensors
Authors: Tsui Lok-kun , Benavidez Angelica D , Garzon Fernando H 
Published: May 2020

Ceramic electrochemical sensors play a major role in chemical analysis of gas species, and mixed potential sensors are attractive for their robustness in harsh environments such as automotive exhaust gases. A major challenge for rapid prototyping of ceramic chemical sensors is the high cost, high material waste, and low geometric flexibility of traditional screen printing and tape casting methods. While these two methods are suitable for mass production of thousands to millions of devices, they tend to be cost prohibitive for small scale rapid prototyping applications. Additive manufacturing techniques enable greater flexibility in working with small batches of materials, customized geometry, and shorter turnaround time.
We will discuss efforts in the additive manufacturing of ceramic mixed potential sensors by extrusion of ceramic and conductor pastes onto zirconia laminates. [1] We evaluated the sensor performance to various test gases at the 100 PPM level including NOX, NH3, and C3H8, observing responses on the order of mV/100 ppm. Electrochemical techniques were employed to probe the effects of porosity on sensor response and evaluate the reproducibility of AM techniques. Finally, we will report on the printing of a ceramic gas sensor by extrusion of a ceramic paste to form the substrate instead of using a laminate substrate to demonstrate a complete device can be produced by AM techniques only.
[1] Tsui, L.K.; Benavidez, A.; Evans, L.; Garzon, F.G. Prog. Additive Manuf. 2019, 4, 1, 13-21
Nonenzymatic Hydrogen Peroxide Electrochemical Sensor Based on Inkjet-Printed Reduced Graphene Oxide
Authors: Shamkhalichenar Hamed , Choi Jin-Woo 
Published: May 2020

The vital role of hydrogen peroxide (H2O2) in many enzyme-catalyzed reactions, has attracted much interest to develop novel approaches for accurate and fast detection of this simple compound [2]. Also, the determination of the hydrogen peroxide level is essential in food processing, environmental analysis, and clinical diagnosis [2]. Reduced graphene oxide (rGO) has shown to be a superior electrode material for electrochemical analysis due to its high electron transfer rate and active surface area [3]. However, the fabrication of such rGO-based electrodes involves complicated and expensive fabrication processes. Herein, we present a disposable, simple, and low-cost H2O2 electrochemical sensor based on rGO for amperometric detection of hydrogen peroxide concentration.
First, the rGO ink material was prepared by mixing 10 ml of graphene oxide (GO) solution with 10 ml of DI water, and sodium dodecyl sulfate (2 mg/ml). The SDS works as a surfactant and reduces the possibility of printer nozzle clogging. The solution was sonicated for 30 minutes and was loaded to a cartridge of an office inkjet printer. To achieve a thicker layer of GO, the printing process was repeated 25 times on a PET film. Next, the electrodes were placed inside hydroiodic (HI) acid for 24 hours at 100 oC to remove oxygenated groups from GO molecular structure. The color of the electrodes became darker after the GO was reduced to rGO (Figure 1.A). Then, the printed pattern was sliced into 20 by 2.5 mm electrodes, and the resistance of the electrode was measured to validate the reduction process.
The step voltammetry method was adopted to measure the H2O2 inside 0.1 M PBS buffer. The solution was stirred at 200 rpm, and -800 mV vs. Ag/AgCl was applied to the working electrode. As it is shown in Figure 1.B, after the addition of 100 µM of H2O2, the current increases due to the reduction of H2O2. Finally, the selectivity of the sensor was evaluated against ascorbic acid and glucose.
In summary, the rGO-based electrochemical sensor was fabricated by inkjet printing graphene oxide with a regular office inkjet printer followed by chemical reduction procedure. The sensor was used to determine the hydrogen peroxide level in aqueous solution. Inkjet-printed rGO electrodes can be used for simple and precise measurement of hydrogen peroxide with high selectivity and sensitivity.
References
[1] W. Chen, S. Cai, Q.-Q. Ren, W. Wen, and Y.-D. Zhao, Analyst, 137 (1), 49-58 (2012).
[2] S. Chen, R. Yuan, Y. Chai, and F. Hu, Microchimica Acta, 180 (1-2), 15-32 (2013).
[3] M. Zhou, Y. Zhai, and S. Dong, Analytical chemistry, 81 (14), 5603-5613 (2009).

Figure 1
Micromechanical Resonators for Ultrasound-Based Sensors
Authors: Farhoudi Navid , Laurentius Lars B , Reiche Christopher F , Magda Jules , Solzbacher Florian 
Published: May 2020

The current field of sensor platforms is substantial, and ever more creative approaches are envisioned and realized. Herein, we showcase a new platform technology for continuous sensing that relies on the resonant absorption of ultrasound waves in a microfabricated array of smart hydrogel structures (see Figure 1).[1] Smart hydrogels are biocompatible and can be tailored to respond to different analytes. [2,3] These selective materials undergo a volume-phase transition in response to changing levels of biomarkers. In addition, smart hydrogels can be based on compositions that include poly(ethylene glycol), poly(methyl methacrylate), or hyaluronic acid to be designed to biodegrade. By employing smart hydrogels as resonator structures and probing them using ultrasound will provide an implantable sensor platform that is minimally invasive, non-destructive, and free of transcutaneous wires.
This approach makes use of the fact that hydrogels can be molded into mechanical microresonators that are tuned to a specific ultrasound frequency. As they swell or contract in response to the presence or absence of the target analyte, their resonance frequency changes, leading to a shift in the ultrasound absorption spectrum. Measuring these changes allows for the reconstruction of the analyte concentration. In addition to that, tailoring the resonance frequency of the smart hydrogel resonator structures to different frequency ranges allows for multiplexing. We successfully demonstrate the use of this platform technology using glucose as a target metabolic marker in-vitro and in-vivo in rats (see Figure 2).
Florian Solzbacher declares financial interest in Blackrock Microsystems LLC and Sentiomed, Inc. Jules Magda declares financial interest in Applied Biosensors LLC.
[1] N. Farhoudi, H.-Y.L., J. Magda, F. Solzbacher and C.F. Reiche, A Biomedical Sensor Based on Resonant Absorption of Ultrasound Waves in Hydrogel-based Resonators. TechConnect Briefs 2019, 2019: p. 412.
[2] Buenger, F. Topuz, and J. Groll, “Hydrogels in sensing applications,” Prog. Polym. Sci., vol. 37, no. 12, pp. 1678–1719, 2012.
[3] A. Peppas, J. Z. Hilt, A. Khademhosseini, and R. Langer, “Hydrogels in biology and medicine:From molecular principles to bionanotechnology,” Adv. Mater., vol. 18, no. 11, pp. 1345–1360, Jun. 2006.

Figure 1
Leveraging Preconcentration and Partial Separations with Silicon Nanowire Arrays to Improve the Detection of Low Volatility Trace Explosive Vapors
Authors: Mullen Matthew , Giordano Braden 
Published: May 2020

Trace detection of explosive vapors in real world environments is hindered by strict sensitivity and selectivity requirements that need to be met in order for these techniques to be effective. The physical properties of most explosive molecules limit environmentally relevant vapor concentrations to the part per billion (ppbv) – part per trillion (pptv) range due to their saturated vapor pressures under real world conditions. Additionally, trace explosive vapor detectors must be able to discriminate against a number of potential chemical and biological interferents present in complex real world environments. In this work, we present silicon nanowire arrays (SiNW) as a novel tunable material aimed at providing trace explosive vapor detectors with the sensitivity and selectivity necessary for operational use.
Dense, highly ordered silicon nanowires are fabricated through a nanosphere lithography process and topped with a porous gold electrode resulting in a high surface area adsorptive substrate intrinsically capable of rapid, precise temperature control via Joule heating. Explosive vapors are selectively preconcentrated onto the SiNW array by exploiting their affinities for the SiO2 surface of the nanowires. Chromatographic like partial separations of preconcentrated material on the array can be achieved through careful selection of desorption parameters. Using a multichannel detector such as an IMS or MS we demonstrate the preconcentration of a number of explosive vapors including 2,6-DNT, TNT, and RDX above and below their saturated vapor concentrations at room temperature, in addition to exploring the effects of desorption flow rates and temperatures on the partial separation of 2,6-DNT, 2,4-DNT, and TNT vapors.

Figure 1
Multishell Nano Structure for Enhancing Fluorescence
Authors: Lin Longhui , Chen Xi , Li Jian-Feng 
Published: May 2020

As an important part of plasmon-enhanced spectroscopy technology, metal surface-enhanced fluorescence provides an effective approach for surface analysis and detection. Our group is interested in exploring how the plasmon effect interacts with emission of probes, such as quantum dots, dye molecules, clusters, rare earth luminescent materials. And we also apply SPR into electroluminescence and chemiluminiscence.
Recently, we have fabricated a type of multishell nano structure which consists of an Au core, an interstitial nanoscale SiO2 layer, and an Au shell layer. Its plasmonic properties result from the strong interaction between the plasmon modes of the Au core and the Au shell, giving rise to hybridized modes that can be tuned into the NIR, for particle sizes below 100 nm in diameter. These interactions also give rise to a strong Fano resonance in the visible region of the spectrum, appearing as an asymmetric modulation in the far-field extinction spectrum of the nanoparticle. Additionally, a monolayer of dye molecules (Cy5.5) was embeded into inner SiO2 layer. Finally, the highest enhanced fluorescence has achieved up to almost 30-fold.The combination of compact size and enhanced light emission with internal encapsulation of the fluorophores for increased biocompatibility suggests outstanding potential for this type of nanoparticle complex in biomedical applications.

Figure 1
Electrochemiluminescence Investigation of Atomically Precise Gold Nanoclusters Decorated with a Bulky Ligand
Authors: Hesari Mahdi , Ding Zhifeng 
Published: May 2020

Electrochemiluminscnce (ECL) is about light generation in the course of an efficient electron transfer in the vicinity of an electrode. ECL has been propagated at the interface of electroanalytical and spectroscopic techniques, and has found worldwide applications in, for example, healthcare, physical and analytical chemistry fields. There have been a vast number of molecules and nanomaterials that are examined as ECL emitters. Among those emitters atomically precise thiolate–protected gold nanoclusters stood out rapidly owing to their well-defined geometric structures and inherent molecular-type opto-electronic properties. Recently, we showed that these gold nanoclusters emit ECL at Near-IR region, that is well-suited for biological applications (e.g., bio-imaging).1 Here, we report one–pot preparation of a gold nanocluster that decorated with a bulky aliphatic ligand (e.g., tert-buthyl thiol). The ECL mechanistic investigations, using conventional and newly established ECL spooling spectroscopy, show that this nanocluster emits ECL light at the Near-IR region.
(1) Hesari, M.; Ding, Z., Acc. Chem. Res.
2017, 50, 218.
Amplification-Free Point-of-Care microRNA Detection in Urine Using Molecular Beacon Based Electrochemiluminescence
Authors: Kerr Emily , Henderson Luke C , Prieto-Simon Beatriz , Voelcker Nicolas H 
Published: May 2020

The burgeoning field of miRNA detection using electrochemiluminescence (ECL) has garnered a great deal of attention in recent times.1 ECL presents many advantages over alternative detection strategies as ECL analyses generally exhibit low-background signals, high sensitivity, are reproducible and scale-able.2 When combined with magnetic-beads for the immobilisation of biological recognition elements, ECL biosensors offer exceptional sensitivity owing to the ability to disperse the beads in large sample volumes to capture the biological target of interest via mixing then concentrate prior to analysis via magnetic extraction.3, 4

Herein, we present a novel biosensor for the sensitive detection of miRNA-21 comprising a molecular beacon ECL probe immobilised on magnetic beads. We obtained a limit of detection of 500 attomoles for miRNA-21 without enzymatic amplification or the addition of detection probes or intercalating labels, negating the need for lengthy and stringent washing procedures to reduce the background signal. Furthermore, we demonstrate the immense potential for point-of-care applications by developing a fully integrated miRNA detection platform. The platform comprises a mini-potentiostat for ECL generation, integrated silicon photodiode for ECL detection and a custom 3D-printed cell holder to readily interface a disposable screen-printed electrode with the potentiostat and photodiode.
We applied our magnetic miRNA extraction technology to the detection of miRNA-21 in human urine, a promising biomarker for the early diagnosis of chronic kidney disease.5 Urine is an ideal sample matrix as it is non-invasive to obtain in large volumes, does not require a phlebotomist to acquire and miRNAs in urine are stable in exosomes. When combined with point-of-care miRNA extraction methods, the molecular beacon based ECL system we have developed presents a promising tool for point-of-care diagnosis and management of numerous diseases.
1. P. K. Kalambate, N. S. Gadhari, X. Li, Z. Rao, S. T. Navale, Y. Shen, V. R. Patil and Y. Huang, TrAC, Trends Anal. Chem., 2019, 115643.
2. Y. Cheng, L. Dong, J. Zhang, Y. Zhao and Z. Li, Analyst, 2018, 143, 1758-1774.
3. M. H. Shamsi, K. Choi, A. H. Ng, M. D. Chamberlain and A. R. Wheeler, Biosens. Bioelectron., 2016, 77, 845-852.
4. W. Liu, X. Zhou and D. Xing, Biosens. Bioelectron., 2014, 58, 388-394.
5. M. L. Alvarez, M. Khosroheidari, R. Kanchi Ravi and J. K. DiStefano, Kidney Int., 2012, 82, 1024-1032.
Degradation of Carbon Electrodes in the Vanadium Redox Flow Battery
Authors: Singh Ashutosh Kumar , Yasri Nael , Pahlevaninezhad Maedeh , Roberts Edward P.L. 
Published: May 2020

The Vanadium Redox Flow Battery (VRFB) is a promising candidate for large scale energy storage. These systems are expected to operate for long cycle life ~ 10 years of lifetime (~ 500 - 2000 charge – discharge cycles).1 The VRFB’s system includes an posolyte (VO2
+/VO2+) and negolyte (V2+/V3+) compartments with carbon electrodes, and uses acidic electrolytes (usually 3M H2SO4). The carbon electrodes in VRFB need to perform in a harsh and corrosive environment associated with the charge/discharge cycling. In this study, we used polyacrylonitrile (PAN) based carbon papers as model carbon electrodes to study changes in the electrodes during cycling operation. The carbon papers were pre-treated according to the conventional approach by heating them in air at 500 ⁰C to incorporate oxygen functional groups on their surfaces.2,3 These pre-treated electrodes were then used in flow battery for 100-cycles at a current density of 80 mA/cm2. At the single cell level, the performance of these electrodes following the operation indicated a slight decrease in voltage efficiency (from 60 % to 52 %). This decrease in performance may be attributed to the electrode degradation during operation. Characterization of the electrode prior and following 100-cycles was performed using Raman spectroscopy, XPS analysis as well as electrochemical studies. Raman analysis showed differences between the fresh and the degraded carbon electrodes, including increasing defect and electronic density distribution. XPS analysis of the degraded electrodes suggest an alteration in the amount of oxygen functional groups. Electrochemical studies showed an decrease in the electron transfer kinetics after degradation, coupled with noticeable difference between the electrodes exposed to the posolyte (VO2
+/VO2+) and negolyte (V2+/V3+). The results provide insight into the stability of the oxygen functional groups during cycling operation which could assist in developing pre-treatment methods to functionalize the VRFB’s electrodes and for other similar electrochemical systems.

References:

(1) Soloveichik, G. L. Flow Batteries: Current Status and Trends. Chem. Rev.
2015, 115, 11533–11558.
(2) Singh, A.; Yasri, N.; Karan, K.; Roberts, E. P. L. Electrocatalytic Activity of Functionalized Carbon Paper Electrodes and Their Correlation to the Fermi Level Derived from Raman Spectra. ACS Appl. Energy Mater.
2019, acsaem.9b00180.
(3) Singh, A. K.; Yasri, N.; Karan, K.; Roberts, E. P. L. Effect of Pretreatment on Carbon Materials. Meeting. Abstract.
2018, MA2018-01, 2391.