bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring of Doping Polybenzimidazole Membranes with Phosphoric Acid: Insights with Spatial and Temporal Resolution
Authors: Arslan Funda , Böhm Thomas , Kerres Jochen , Thiele Simon
Published: July 2021

Keywords: Acid Doping Level (ADL), Fuel Cells (FCs), High Temperature (HT), Polymer Electrolyte Membrane (PEM), Phosphoric Acid (PA), Polybenzimidazole (PBI), Raman spectroscopy

High temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are one of the most promising energy conversion devices with zero local CO2 emission. The polymer electrolyte membrane placed between the anode and cathode plays an important role for the overall fuel cell efficiency. The current state-of-the-art membranes used in HT-PEMFCs are PBI-based materials. Compared to Nafion®-based systems used in low temperature PEMFCs, they allow operation at temperatures up to 180-200 °C and do not require water management. Other advantages of the elevated operation temperature are e.g. accelerated reaction kinetics and tolerance improvement against impurities such as carbon monoxide. However, PBI-based membranes are not intrinsically proton conductive and therefore need to be doped with acid in order to ensure proton conductivity. The acid of choice is phosphoric acid due to its non-volatility and thermal stability.

Acid doping levels are important since they have a huge influence not only on conductivity, but also onto mechanical and thermal properties of a membrane. Commonly, weighing and titration are used to determine the doping level, but they are bulk sensitive only. In this work, confocal Raman microscopy was used to provide temporal and spatial insights into the acid doping process. It can be performed on the membrane before or after application in a fuel cell due to its non-destructive nature. Our results show that acid doping is a diffusion-limited process. Considerable changes in spatial distribution of dopant were observed within the membrane before reaching saturation. Further monitoring of diffusion of phosphoric acid after removal from the doping solution shows that the diffusion continues even after months. Confocal Raman microscopy offers the option to gather information non-destructively and contact-free from within the membrane. The insights into the phosphoric acid doping process of PBI-based membranes presented here are of great importance for the manufacturing and optimization process of high temperature fuel cells and their overall efficiency.
Study of Deuterium Isotope Separation By Anion Exchange Membranes Water Electrolysis
Authors: Sato Haruka , Matsushima Hisayoshi , Ueda Mikito , Ito Hiroshi
Published: July 2021

1. Introduction

Hydrogen energy is one of solutions for decarbonized society. Water electrolysis is promising as hydrogen production. Currently, water electrolysis with a solid polymer electrolyte membrane has been developed. The electrolysis using a cation-exchange membrane (PEM) has been widely used, while one using an anion-exchange membrane (AEM) is studied as a next-generation method with nonprecious catalysts.

Hydrogen isotope separation is applied as a new application of water electrolysis. The nuclear fusion reactor ITER, which uses deuterium and tritium as fuel, will be operated around 2035 when the isotope separation/enrichment technology will be required.

We have studied deuterium (D) separation by both PEM- and AEM-type. The separation ability of PEM electrolysis remarkably depended on the ratio of water supplied to the current density (stoichiometric ratio: λ) [1]. Interestingly, AEM one was better than PEM [2]. In this study, AEM electrolysis was investigated at various λ in order to improve the separation performance.

2. Experimental

The electrolyte was 0.1 M KOH with 10 at% D. The D concentration was adjusted by D2O. The electrolyte was supplied from the lower part of only the anode side. The ready-made AEM (A201, Tokuyama) was employed as electrolyte. Pt catalyst was used as the anode catalyst and CuCoOx was used as the cathode one. The electrolysis was conducted at constant current densities or water feed at room temperature. The hydrogen gas was analyzed by a quadrupole mass spectrometer to determine the mass number (m = 2 (H2), 3 (HD), 4 (D2)), while the solution discharged from the anode was investigated by FTIR using the attenuated total reflection (ATR) method with a diamond prism.

3. Results and discussion

Figure 1 shows the D content in hydrogen gas evolving from the cathode. In the figure, αgas indicates the separation factor, which is the ratio of protium (H) atomic concentration of the gas to the supplied water. The value of αgas decreased with decreasing λ. The present result suggests H dilution in the gas as well as PEM-type. It should be noted that AEM one could be electrolyzed and keep draining the electrolyte from the anode even at λ ≤ 4, while PEM-type discharged the almost all volume of the electrolyte from the cathode side [1]. This might be explained by the mass transportation by the diffusion and electroosmosis whose flows direction depend on the membrane type.

In our presentation, the other results such as D concentration in electrolyte and pH variation depending on λ will be introduced. We will discuss the D separation mechanism by AEM electrolysis from the viewpoints of the water distribution and the mass transportation in the membrane.

References

K. Harada et al., Int. J. Hydrog. Energy, 45 (2020) 31389-31395.

.H. Matsushima et al., Int. J. Electrochemical Society, 166 (10) F566-F568 (2019)

Figure 1
An Experimental Study of Graphene-Based Conductive Ink for Inkjet-Printable Electronics
Authors: Qualls Hayden , Kehoe William , Stehle Yijing
Published: July 2021

The field of printable electronics and sensors has been experiencing increased interest and growth to meet the demands of low-cost, flexible, and lightweight devices. From this subset of devices, graphene-based printable electronics and sensors are of specific interest due to their transparency, flexibility, biocompatibility, and high conductivity. Among all modern ink printing technology, screen printing, spray coating, 3D printing, and inkjet printing are often utilized to fabricate flexible electronic applications from conductive ink. Compared with the other three, inkjet printing has received the most attention due to the simple printing process, high repeatability, economy, and time-savings compared to other printing techniques. However, inkjet printing often suffers from nozzle clogging due to aggregation of the particles in the conductive inks. In this research, a conductive graphene-based ink is developed to be used in a regular inkjet printer. Our goal is to fabricate this ink such that it is flexible, biocompatible, and easily manufacturable. This method seeks to create a low viscosity, high surface tension ink that addresses the clogging of the nozzle due to an aggregation of particles and is capable of being printed through a regular inkjet printer. By selectively choosing and modifying the composition and processes of ink formulation methodologies of past research, a graphene-based conductive ink that is compatible with inkjet printing is formulated. A flexible hydration sensor is printed out with this graphene-based conductive ink through which its conductivity and sensitivity are compared with the same sensor printed with commercially available graphene ink.
Efficient Metal Oxide-Based Electrocatalysts for Applications in Hydrogen Fuel and Metal-Air Batteries
Authors: Ingsel Tenzin , Gupta Ram
Published: July 2021

Energy drives advancement in different sectors of human society. Cost-effective green energy sources are highly sought-after entities that can provide solutions to the worldwide energy crisis concerns. Among different types of green energy storage and conversion materials, energy via water splitting is regarded as one of the most assuring techniques to generate clean hydrogen fuel and oxygen for metal-air batteries. In this research, nanostructured metal oxides were synthesized through a facile hydrothermal process for water splitting application. Cobalt oxide was doped with iron where the elemental compositions of iron-cobalt were varied as x = 0, 0.2, 0.4, 0.6, 0.8, and 1 in FexCo3-xO4. It interests the scientific community in understanding the effect and role of dopant on materials electrocatalytic and electrical properties to deliver smart design for various applications. Among various samples, Fe0.6Co2.4O4 showed the best performance for water splitting by requiring the lowest amount of energy to generate hydrogen and oxygen. The synthesized materials were found to be electrochemically stable and can be reused many times for water-splitting applications. Our research provides cost-effective materials for green energy production.
The First Analytical Method Allowing the Quantitative Determination of a Novel Promising Anticancer Agent Candidate
Authors: Kozak Jędrzej , Tyszczuk-Rotko Katarzyna
Published: July 2021

The subject of this study is a chemical compound called ethyl 8-(4-methoxyphenyl)-4-oxo-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazine-3-carboxylate (EIMTC). This substance was found to have good bioavailability as well as low toxicity both in vitro and in vivo.

This work presents for the first time a sensitive voltammetric procedure for the determination of a compound with anticancer activity in human serum using a screen-printed sensor with a carbon working electrode modified with carbon nanofibers. After optimizing the procedure, a linear calibration curve was obtained in two concentration ranges from 2 × 10-9 to 2 × 10-8 mol L-1 and from 2 × 10-8 to 2 × 10-7 mol L-1. The calculated limits of detection and quantification were 5.0 × 10-10 and 1.7 × 10-9 mol L-1 respectively. The method was applied for the determination of the EIMTC in human serum samples after the previous removal of the protein using trichloroacetic acid (TCA).

[1] Tyszczuk-Rotko, K., Kozak, J., Sztanke, M., Sztanke, K., Sadok, I. Sensors
2020
, 20(18), 5217-5227.
A Greener Synthesis of Fe-N-C Catalysts for the Oxygen Reduction Reaction
Authors: Gernhard Marius , Roth Christina
Published: July 2021

The world is faced with an ever-increasing energy demand that, under the aspect of global warming, must be covered by renewable sources such as wind- and solar energy. However, the main challenge linked to these sources is to provide a continuous energy supply, demanding highly efficient energy storage and conversion devices.

One promising conversion technology are fuel cells. [1] These usually rely on expensive and rare platinum group metal (PGM) catalysts for the sluggish oxygen reduction reaction (ORR). In order to serve the human energy demand, cheap and scalable fuel cell systems are required. The class of M-N-C (M = Fe, Mn, Co) type catalysts shows particularly good catalytic behaviour comparable to PGM based catalysts. However, promising catalysts are usually synthesised from toxic materials with solvent and energy intensive methods. [2]

Here, we present a synthetic approach towards Fe-N-C type catalysts, that uses only non-hazardous chemicals, produces no wastewater and is more energy efficient than classical approaches. We used iron hydroxide as iron source for its lower environmental impact as compared to ferric chloride. Cyanoguanidine (non-toxic) was chosen over cyanamide (toxic) as a pore forming agent and nitrogen source. Tryptophan was used over PANI and the like for its availability from natural sources with no need for toxic precursors. Instead of classical wet chemical approaches we used a solvent free mechanochemical synthesis. And by using vulcan carbon as electron conducting scaffold, we were able to carbonize at 750 °C, increasing the overall energy efficiency. The catalytic activity towards the ORR of the obtained catalysts was determined by rotating disc electrode measurements in acidic and basic media. With a 100 mV lower onset potential, their performance in an alkaline environment is good but not quite comparable to Pt based catalysts.

Future studies will focus on the correlation of nitrogen content as well as porosity of the catalysts with their electrocatalytical behaviour.

[1] I. Staffell, D. Scamman, A. Velazquez Abad, P. Balcombe, P. E. Dodds, P. Ekins, N. Shah, K. R. Ward, Energy Environ. Sci.
2019, 12, 463–491.

[2] H. T. Chung, D. A. Cullen, D. Higgins, B. T. Sneed, E. F. Holby, K. L. More, P. Zelenay, Science
2017, 357, 479-484.

Figure 1
Development of the Electrochemical Chip for Early Detection of Mastitis-Somatic Cell Count and Evaluation of Immune Function
Authors: Kumagai Ryoma , Prasad Ankush , Takanashi Haruka , Kasai Shigenobu
Published: July 2021

Somatic cell count (SCC) is widely used to monitor bovine mastitis. Dairy farmers in Japan must send bovine milk to a laboratory for this inspection because the SCC device is large and expensive. In recent years, focusing on the increase in neutrophils in the early stage of mastitis, the method that can test for an early stage of mastitis by evaluation of the immune function of somatic cells in milk have been studied.

In the current study, we previously evaluated cellular respiratory activity1. And we evaluated somatic cell count by elevation of respiration activity of somatic cells in milk and elevation of immune function by phorbol 12-myristate 13-acetate(PMA)-stimulated respiratory burst measurement using scanning electrochemical microscopy (SECM)2. In addition, we developed an electrochemical chip that enables counting of somatic cells in milk and evaluation of immune function. In SECM, we applied the oxygen reduction potential using a Platinum (Pt) microelectrode as a probe, scanned the vicinity of cells and between bulk and calculated the oxygen consumption of cells from the difference in current value between the two points to evaluate respiration activity.

Fig.1A shows the arrangement of the electrodes. We made electrochemical chips by photolithography with multiple Pt electrodes and used SU-8 to form an insulating film to determine the electrode size. Fig. 1B is a schematic representation of a well prepared with Polydimethylsiloxane (PDMS). This well can hold 100 µL of sample/solution. Fig. 1C shows the method of respiration activity evaluation and respiratory burst evaluation using the electrochemical chip. There is only the measurement solution (11.4 mM glucose-containing phosphate buffer) in Ch1 well and milk sample in ch2 well while ch3 well contains milk sample containing PMA. We evaluated the respiration activity of somatic cells in milk from the difference in oxygen reduction current value between Ch1 and Ch2 (ΔI1) and estimated the number of somatic cells. We compared the difference in oxygen reduction current value (ΔI2) of Ch2 and ch3 with ΔI1 and evaluated the immune function by evaluation of respiratory burst. Our study will report the results on the number of somatic cells and the real-time monitoring of the respiratory burst.

References

(1) H. Kikuchi, A. Prasad, R. Matsuoka, S. Aoyagi, T. Matsue, S. Kasai: Frontiers in Physiology 7, 25, 1-6 (2016)

(2) R. Kumagai, A.Prasad, S. Kasai, PACIFIC RIM MEETING on electrochemical and solid state science 2020, 11.4-9. 2020

Figure 1
3D Architected Solid-State Lithium-Ion Battery
Authors: Sun Yuchun , Narita Kai , Saccone Max A. , Lee Seola , Greer Julia R.
Published: July 2021

Lithium-ion batteries are more and more widely used in portable electric applications with high power demand. Most approaches to high-power batteries gain improvement in power density on the cost of energy density. The rapid development in additive manufacturing technique in the past decade has provided a promising pathway to achieve higher power density without sacrificing energy density, where the ion diffusion distance between electrodes is minimized by improving electrode architectures. Recent approaches in 3D lithium-ion batteries with interdigitated configuration demonstrated new electrode fabrication methods through direct ink-writing. Although the power densities were improved, the large portion of organic materials in electrode inks for adhesion purpose became the “dead weight” in batteries, and also decreased the electrical conductivity of electrodes. In this work, we demonstrate a new method to fabricate 3D interdigitated lithium-ion battery with architected carbon anode, lithium cobalt oxide (LCO) cathode, and gel polymer electrolyte. An oligo(ethylene glycol)-based gel polymer electrolyte was polymerized in-situ when the resin was in direct contact with the electrodes to achieve a highly adherent interface. Stereolithography (SLA) technique was used to 3D print an architected electrode structure with feature size less than 200 μm using an acrylate-based photoresin. The printed polymer structure went through a pyrolysis process, and 3D architected carbon anode was obtained. The architected LCO anode was also fabricated using an SLA system, but through a “swell-in” — calcination method, where lithium and cobalt ions were swelled into a 3D printed hydrogel, and after a calcination process the 3D architected LCO cathode was obtained. The electrodes fabricated in this work have overcome difficulties in reducing the portion of organic materials in 3D printed electrodes, resulting to a 3D interdigitated lithium-ion battery with large percentage of active materials, high electrical conductivity in electrodes, and small ion diffusion distance between electrodes.
Validation of a Low-Cost on-Demand Compact Ozone Covid-19 Sterilization Chamber
Authors: Ebeling Daniel , Werner John , Erbe Jarrod , Ebeling Silas , Miao Qiusu , Ebeling Alyssa , Sanford Laura , Boinski Connor , Salous Bilal , Scheunemann Alyssa , Peaslee David , Ploense Lloyd , Ploense Robert , Stetter Edward , Findlay Melvin , Meulendyk Bennett , Lee Mitchell , Patel Vinay , Stetter Joseph R.
Published: July 2021

The COVID-19 pandemic has resulted in limited availability of N95 masks and other personal protective equipment (PPE). The sterilization and re-use of PPE can be of immediate benefit to help alleviate shortages and offer peace of mind to healthcare workers. Also, an inexpensive, precise, and portable sterilizer will have many applications beyond the current health crisis in a variety of field disaster relief operations. The sterilization of PPE and medical or other instruments will reduce costs, improve safety, and reduce waste. The portable sterilizer can also be utilized by individuals and businesses outside of the health care sector with similar benefits.

Ozone sterilization does not require chemical consumables, uses ambient oxygen to generate ozone on site, and results in no toxic residuals. KWJ Engineering led the development of a small benchtop sterilizer with on board ozone generation controlled by feedback from an electrochemical sensor module and complete with an ozone destruct cycle for safety. Relative humidity as well as temperature and O3 concentration are also continuously recorded and can be maintained at the most effective levels for sterilization.

Validation of the ozone sterilization protocol for deactivation of surrogate viruses on N95 masks has been demonstrated using TLS, an E. coli bacteriophage (bacteria-infecting virus), to provide a measure of effectiveness for variables such as time, ozone and viral concentrations, temperature, relative humidity, and virus-contaminated substrate. Additional organisms and conditions of sterilization are reported in this study to provide further analysis of efficacy of equipment and procedures as well as deleterious effects, if any, on PPE.

The experiments with bacteriophage indicate that there is 99.99% inactivation of the robust bacteriophage when placed on N95 mask material with a one-hour treatment at 200 ppm ozone as compared to a 0-ppm control. The inactivation was shown to be 99.8% with only 50 ppm ozone. These ozone levels are easily achieved with a low power source and the entire system is operated using 12 VDC from a charger or battery. This sterilization effect is highly dependent on humidity, and the higher inactivation rates require higher relative humidity. The inactivation was demonstrated on multiple types of substrates with and without prior drying of the deposited phage. We expect the covid19 to be easier to inactivate than the bacteriophage and will test the system on SARS-CoV2 in a separate series of experiments. The sterilizer apparatus is simple and low cost and can be constructed from readily available parts and software for automated control is open sourced by KWJ.
Electronic Spiking Protein-Based COVID Sensors
Authors: Tabib-Azar Masood
Published: July 2021

Viruses are ultimate nanotechnology objects with cleverly designed capsid proteins to bind with cell membranes and exquisite DNA/RNA machinery to invade cells and replicate themselves using cells' machinery. Here I will discuss an electronic virus sensor that uses aptamers designed to bind with the COVID-19 spiking proteins S1 and S2 to capture the virus inside a quantum mechanical tunneling gap device. The current through the gap, that is sized to match the COVID-19 diameter of 125 nm, is monitored to detect the presence of the virus. The gap impedance also changes and can be monitored. The sensor works with small amount of saliva deposited over its active area. Saliva is a complex fluid composed of 99.49% water, enzymes, human cells, bacteria, opiorphin, haptocorrin, alfa-amylase, antibacterial compounds, mucus, and electrolytes (sodium, potassium, calcium, etc.). It also contains 60 nm -100 nm exosomes. Except for human cells, bacteria and exosomes, all other fresh saliva components have small molecules (mucus can produce large particles in old saliva). Exosomes and any other nanoparticles inside the fresh saliva can potentially produce false positive results. False negative results, on the other hand, are produced when the viruses in the saliva do not bind with the sensor aptamers. Filtering is used to exclude large (>200 nm) particles. Ultrasonication as well as electric field biasing/excitation techniques are used to ensure virus-aptamer encounter and binding. Exosomes' sizes make them difficult to exclude using filtering. Currently I am developing a technique based on dielectrophoretic responses of exosomes and viruses to preferentially trap the COVID-19 and repel the exosomes. The sensor's limit of detection is close to a single virus owing to its transduction technique of quantum mechanical tunneling current. I will discuss COVID-19 electronic sensor performance and its performance along with its fabrication and applications in this talk.
Investigate Thermodynamic and Kinetic Degradation of Lithium-Ion Batteries through a Combined Experimental and Modeling Approach
Authors: Jin Xinfang , Duan Xiting
Published: July 2021

With the significant cost reduction of Li-ion battery (LIB) (85% in the past 10 years), 50-fold growth in market penetration of the technology has been projected through to 2030 for modern transportation and renewable energy integration [1]. LIB is a high energy density, high round-trip efficiency, high reliability energy storage device [2]. Different from Internal Combustion Engine, as a power generator, LIB pack is sealed in a certain container and its status need to be estimated by additional diagnostic instruments with specific electrochemical performance data. The traditional methods to estimate State of Charge (SOC) and State of Health (SOH) include current integration method and open circuit voltage method, which are time-consuming (over 1 day) and rely on historical information of the system [3]. Impedance spectroscopy technique can capture both thermodynamic and kinetic information of the LIB in a relatively short time, however, it is difficult and sometimes unreliable to interpret the data by using a simplified equivalent circuit method (ECM). In our recent publication [4], we also find that nonideality effect caused by interaction among high concentration Li ions could lead to nonlinear transport and kinetic parameters as a function of SOC. In this research work, we would like to use the perturbation form of a physics-based LIB model considering the nonideality feature of the cell to deconvolute the electrochemical impedance spectroscopy (shown in Fig.1) of a LIB coin cell operating under different SOCs and different number of cycles. After proper status evaluation of beginning of life (BOL) of the cell, parasitic side reactions, the solid electrolyte interface (SEI) formation in anode and cathode, are included as the indicators of degradation. A nonlinear optimization procedure will be used to identify the parameters associated with the cell capacity loss in each electrode, solid/liquid interface reaction, Li-ion diffusion, ohmic resistance, etc. The results will map out the cell capacity loss caused by thermodynamic degradation and deteriorated reaction kinetics and diffusivity caused by the growth of the SEI layers during cycling. It will provide important guidance in designing fast and accurate LIB real-time diagnostic devices.

References:

[1] BloombergNEF, https://about.bnef.com/blog/behind-scenes-take-lithium-ion-battery-prices/

[2] Jing Xie, Yi-Chun Lu, A retrospective on lithium-ion batteries, Nature Communications volume 11, Article number: 2499 (2020)

[3] Wen-Yeau Chang, The State of Charge Estimating Methods for Battery: A Review, ISRN Applied Mathematics. Volume 2013, Article ID 953792, 7 pages

[4] B Ng, X Duan, F Liu, E Agar, RE White, WE Mustain, X Jin, Investigation of Transport and Kinetic Nonideality in Solid Li-Ion Electrodes through Deconvolution of Electrochemical Impedance Spectra, Journal of The Electrochemical Society 167 (2), 020523

Figure 1
Multiphysics Model of the Thermal Behavior of a Lithium Metal Solid State Battery
Authors: Johnson Nathan B , Albertus Paul
Published: July 2021

While it is often stated that solid state batteries are safer than Li-ion batteries with liquid electrolytes, especially for the case of solid state batteries with a lithium metal anode (and hence a higher specific energy than a conventional Li-ion cell), the thermal behavior of the cell upon external heating, internal shorting, and other forms of abuse or failure requires careful analysis. We address this question by building a thermal model of a large-format (e.g., 60 Ah class) cell, making use of chemical reactivity data obtained from a complete solid state battery within a differential scanning calorimetry (DSC) pan. We use our model to simulate a thermal ramp test and short-circuit to study the thermal behavior of an LCO|LLZO|Li metal prismatic cell. Our model allows us to assess the temperature at which self-heating and thermal runaway occur, in addition to the amount of heat that is generated and the rate of heat generation. Our presentation will cover our model formulation, the experimental basis for the self-heating reactions, and results including temperature, reactant consumption, and heat evolution throughout the duration of each thermal stress test. We may also discuss our experimental work to expand on available DSC data for all-solid-state cells and present thermogravimetric analysis as well as DSC data for different solid-state battery chemistries.
Detection of Volatile Organic Compounds in Contaminated Air Using Gas Sensors with Machine Learning
Authors: Shin Woosuck , Itoh Toshio , Koyama Yutaro , Akamatsu Takafumi , Tsuruta Akihiro , Masuda Yoshitake , Uchiyama Kazuhisa
Published: July 2021

We investigate selective detection of target volatile organic compounds (VOCs) as unpleasant odor substances in the presence of interference VOCs from car interiors. We selected four unpleasant odor substances as target gases, such as age-related body odors and fungi, and two interference VOC substances, such as the main olfactory components from car interiors, in this study. We used eight semiconductive gas sensors including six general semiconductive gas sensors and two bulk-response type semiconductive gas sensors. Discrimination of each target gases was carried out using machine learnings, such as principal component analysis (PCA) and linear discriminant analysis (LDA), which are dimensionality reduction methods. PCA is an unsupervised learning method, and finds the axis that maximizes the data’s variance. LDA is a supervised learning method, and finds maximizes the separation between multiple classes. The machine learnings used sensor responses (r=Ra/Rg; r: sensor responses, Ra: resistance in humid pure air or in contaminant, Rg: resistance in the target gases) from all sensors.

The plots of PCA scores tended to move radially outward as concentrations of target gases increased. PCA scores of target gases with contaminants showed almost the same as those of lower concentration target gases without contaminants. However, the PCA scores in the presence of contaminants were within the area of each target gas so that the discrimination between the target gases was almost achieved. The LDA scores were classified by target gases without concentrations of target gas and contamination, so the LDA scores tended to aggregate with target gases. The plots of LDA scores seemed to be more gathered in each class (target gas) area than those of PCA scores.

Moreover, we investigated to reduce the number of sensors using another machine learning, i.e. feature selection technique, which used the sensor responses for obtaining sensor weights against all data. Based on the results of another machine learning, we selected three sensors which possess high scores in another machine learning. The PCA and LDA scores from selected three sensors showed almost the same qualities as those from eight sensors, whereas those from non-selected sensors cannot discriminate target gases, so the amount of information of the target gases has been reduced by excluding the selected three sensors for separating each target gas. From this result, it is possible to reduce the number of sensors to keep the discrimination between target gas by selecting sensors obtained using feature selection techniques.

Ref. T. Itoh, Y. Koyama, W. Shin, T. Akamatsu, A. Tsuruta, Y. Masuda, K. Uchiyama, Sensors 2020, 20, 2687.

Figure 1
Use of Statistical Methods for the Interpretation of Peruvian Wines Measurement Results with MOS Electronic Noses
Authors: Sun-Kou Rosario , Paredes-Doig Ana , Picasso Gino , La Rosa-Toro Adolfo , Doig-Camino Elizabeth
Published: July 2021

The use of statistical methods for the treatment of information from a data set has been used to be able to better interpret the results obtained in the analysis of different samples. An example, the most common, of these statistical methods used is the Principal Component Analysis (PCA). But, other techniques like Cluster and Factorial analysis allow to have too a better idea of the results.

The tin oxides palladium or platinum doped were first prepared by the wet impregnation method. The sensors were made with the screen-printing method to print gold electrodes on alumina plates and finally the oxides, in a mixed with terpineol and ethyl celulose, were put on the electrodes surface. Then, some oxides were modified with a coating of Zeolite Y.

With the sensors made in the laboratory, two electronic noses were built. One of them, of platinum doped tin oxides and the other of Palladium (with and without Zeolite Y coating). The sensing of the wines was monitored with the LabVIEW software and the statistical methods were applied with the XLSTAT software. It was observed that for the nose of platinum sensor a difference in the groups of commercial and unknown wines was shown. This difference is attributed to the brand or origin of the wines. While the nose of palladium sensors allowed to distinguish the strains because it locked the Borgoña wines in a different conglomerate. This could be observed with the PCA, cluster and Factorial methods, complementing the three methods the statistical information.

The cluster method allowed classifying the results obtained with the detection of Peruvian wines, both when using palladium- and platinum-doped oxides. In both cases, it was possible to differentiate commercial wines from those of unknown brand. In addition, in each case one of the wines was distinguished by some characteristic. For example, the DM (Dulce Mistela) is different than the other wines of unknown brand since these other three are Borgoña. It was observed that the distances between classes are optimal when platinum-doped sensors are used, since the interclass variation exceeds 80%.

It is important to note that the results obtained with the factorial analysis mainly reinforce and complement the Cluster analysis, with which very similar groups were obtained, if not practically the same.

For example, using Factorial analysis, it is clearly observed that E-Nose 1 (Electronic nose made up of tin oxide-based sensors doped with different concentrations of platinum (0.1; 0.2; 0.3 and 0.5% Pt) with and without zeolite coating, and with three additional commercial sensors) separates the wines into two groups that are well differentiated: the known commercial wine (blue circle) from the unknown (red circle). It is also observed that the variance value of the two factors is high 99.26%. That could be seen in Figure 1.

Figure 1
F- MWCNT/ ZnO Nanocomposites for Real-Time Detection of Ammonium Level in Paddy Field
Authors: A Akshaya Kumar , S K Naveen Kumar , Baburaj Aiswarya , Fernandez Renny Edwin , Khosla Ajit
Published: July 2021

Real-time monitoring of Ammonium (NH4
+) concentration level in the soil would improve the management of the nutrients in smart agriculture. This paper reports the development of the F-MWCNT/ZnO nanocomposites based miniature sensor arrays for real-time monitoring of NH4
+ in the paddy field. Screen printing of Copper (Cu) electrodes over the fiber epoxy followed by a spin coating of F-MWCNT/ZnO active layer structure was found to have a proportional impedance change with NH4
+ concentration levels. The multiplexed sensor arrays were designed and tested with the standard and extracted water samples from the field. The sensor offers a higher sensitivity of 67.13 mM/ Ω in the linear range of 1 -10 mM NH4
+. Further, sensor arrays were facilitated using an IoT enabled NodeMCU microcontroller platforms for real-time monitoring of NH4
+ concentration levels in the paddy field
(Invited) Electrochemical Microbiosensors for In Vivo Monitoring of Neurotransmitters
Authors: Andreescu Emanuela
Published: July 2021

Measurements of neurotransmitter concentrations in blood and tissues are of great physiological and pathological importance and could be useful for monitoring and understanding the state and progress of a variety of neurological diseases. Electrochemical microbiosensors can provide real-time measurements of neurotransmitters, but sensors that function reliably and maintain accuracy in hypoxic environments are limited. This presentation will describe an enzyme-based electrochemical sensing technology that enables real time monitoring of key analytes associated with neural signaling and function during ischemia and high frequency stimulation. To design our sensors we utilize unique redox, catalytic and oxygen storage/release properties of ceria nanoparticles, originating from their dual oxidation state and the highly mobile lattice oxygen present at their surface. The construction and analytical performance of several enzyme sensors based on these nanoparticles will be discussed, along with results demonstrating their capabilities for monitoring of neurological activity (dopamine, lactate, glutamate) during hypoxia in brain slices and in intact awake animals, with high sensitivity, wide linear range, and low oxygen dependence. The results demonstrate promising characteristics of ceria nanoparticles as a biosensor material for in vivo monitoring of oxidase enzyme substrates, particularly in settings where the availability of oxygen may be limiting. The use of these materials opens new avenues for application of this technology in different fields such as biosensors, biofuel cells, point-of-care testing and implantable diagnostic devices.
(Invited) Potential Applications of Nano-Electrochemistry in Point-of-Care Sensing Devices
Authors: Chung Julia , Hertler Pheobe , Plaxco Kevin W. , Sepunaru Lior
Published: July 2021

Using low noise electronics and micro-electrodes we can now electrochemically detect and count single, nanometer-scale objects in solution.1,2 This talk will cover recent discoveries in the field of single entity electrochemistry showing that electro-inactive species, including proteins, DNA, and even cells, can be detected individually using unmodified electrodes.3–5 Despite these advances, however, limitations persist. The location upon which the individual analyte adsorbs onto the electrode surface influences the magnitude of the electrochemical signal it produces.6,7 Consequently, the electronic output does not reflect the true physical properties of the biological entity, thus inhibiting the analytical resolution desired for applications.

In response, we have shown that coupling the electrochemical reaction to a homogeneous, rate-limiting chemical reaction ameliorates this problem, improving the precision of single-entity electrochemical blocking measurements. Using both finite element simulations and experimental statistical analysis we provide guidance for the sizing of redox-inactive materials with high analytical precision under a range of conditions, including variations in electrode size and analyte concentration. The presented nanoscale electrocatalytic approach could offer a novel means of achieving cost-effective, rapid, real-time detection of nanometer-scale “insulators” in complex media, an advance that could be of significant relevance to point-of-care medical diagnostics.

References:

(1) M. Crooks, R. Concluding Remarks: Single Entity Electrochemistry One Step at a Time. Faraday Discuss. 2016, 193 (0), 533–547. https://doi.org/10.1039/C6FD00203J.

(2) V. Sokolov, S.; Eloul, S.; Kätelhön, E.; Batchelor-McAuley, C.; G. Compton, R. Electrode–Particle Impacts: A Users Guide. Phys. Chem. Chem. Phys. 2017, 19 (1), 28–43. https://doi.org/10.1039/C6CP07788A.

(3) Bard, A. J.; Zhou, H.; Kwon, S. J. Electrochemistry of Single Nanoparticles via Electrocatalytic Amplification. Isr. J. Chem. 2010, 50 (3), 267–276. https://doi.org/10.1002/ijch.201000014.

(4) Quinn, B. M.; van’t Hof, P. G.; Lemay, S. G. Time-Resolved Electrochemical Detection of Discrete Adsorption Events. J. Am. Chem. Soc. 2004, 126 (27), 8360–8361. https://doi.org/10.1021/ja0478577.

(5) Deng, Z.; Renault, C. Detection of Individual Insulating Entities by Electrochemical Blocking. Curr. Opin. Electrochem. 2021, 25, 100619. https://doi.org/10.1016/j.coelec.2020.08.001.

(6) Fosdick, S. E.; Anderson, M. J.; Nettleton, E. G.; Crooks, R. M. Correlated Electrochemical and Optical Tracking of Discrete Collision Events. J. Am. Chem. Soc. 2013, 135 (16), 5994–5997. https://doi.org/10.1021/ja401864k.

(7) Deng, Z.; Elattar, R.; Maroun, F.; Renault, C. In Situ Measurement of the Size Distribution and Concentration of Insulating Particles by Electrochemical Collision on Hemispherical Ultramicroelectrodes. Anal. Chem. 2018, 90 (21), 12923–12929. https://doi.org/10.1021/acs.analchem.8b03550.
(Invited) Theranostics with Lanthanide Doped Nanoparticles
Authors: Vetrone Fiorenzo
Published: July 2021

In recent years, a significant amount of research has focused on nanoparticle-based “theranostic” agents for the treatment of a wide array of diseases, including cancer. This new paradigm in personalized medicine intends to exploit nanoplatforms that carry both therapeutic and diagnostic (theranostic) modalities. Compared with delivering drugs or imaging agents separately, theranostic agents can simultaneously deliver them to specific sites, enabling detection and treatment of disease in a single procedure. Many theranostic nanoplatforms are triggered by light, however, the vast majority of these are limited in that the ultraviolet or visible excitation light used has minimal applicability in biological applications. Lanthanide doped nanoparticles, on the other can be excited with biologically friendly near-infrared light (in the biological windows) and can emit in the ultraviolet, visible or near-infrared regions through a multiphoton upconversion process while simultaneously emitting in the near-infrared region through a Stokes or downshifted process. Hence, the upconversion luminescence can be used to trigger the therapeutic application (drug delivery, photodynamic therapy, etc.) while the near-infrared luminescence can be used for the diagnostic modality (bioimaging, nanothermometry, etc).

In this presentation, we will introduce lanthanide doped nanoparticles and demonstrate their usefulness in theranostics. In particular, we will show complex nanoparticle architectures can endow further functionality to these nanoparticles including the ability to decouple the theranostic processes that are conventionally delivered simultaneously.
(Invited) Plasmonic and Surface Plasmon Electrochemiluminescence Sensors for Detecting Biomarkers and Drugs
Authors: Masson Jean-Francois , Polo Federico
Published: July 2021

In this presentation, a series of different plasmonic sensors for the detection of cancer biomarkers, COVID-19, cancer therapeutic drugs and the response of patients to oncological biological drugs will be presented. The plasmonic sensors are based on a portable 4-channel SPR instrument and surface chemistry developed to present fouling of the sensors in crude serum or plasma. Sensors for detecting methotrexate and for the immune response induced by asparaginase in leukemia treatments directly in sera of patients during ongoing therapies will be presented. Our work towards the detection of HER-2 positive breast cancers will also be presented, with a comparison of commercial and point of care SPR instruments. Our initial work on the development of a SPR-electrochemiluminescence instrument will be presented. We recently revealed that performing SPR and electrochemiluminescence on a single instrument provides unprecedented information about the interfacial processes occurring on the electrode. In addition, studying the energy transfer between the ECL and the plasmon revealed that the optically excited plasmon reduced the ECL intensity in the far-field by about 40% due to a lower plasmon mediated luminescence process. Hence, the combination of SPR and ECL is highly advantageous to study electrochemical processes.
(Invited) Rational Design of NIR-II Optofunctional Materials for Biomedical Applications
Authors: Li Ming
Published: July 2021

The second near-infrared (NIR-II) biological window operating in the wavelength range of 1000-1700 nm is of considerable current interest for biomedical applications. This is mainly attributed to the high biological tissue penetration depth of the NIR-II light because of the less absorption and low optical scattering. However, previous studies regarding NIR-II optical materials mainly focused on the fluorescent upconversion nanomaterials, carbon nanomaterials, organic molecules and polymers for fluorescent bioimaging, photothermal/photodynamic therapy, and photoacoustic imaging. As is well-known, these optofunctional materials have limitations of low fluorescence efficiency, poor stability and poor multifunctionality. This talk will introduce NIR-II plasmonic materials recently developed in our lab for versatile biomedical applications. We have developed NIR-II plasmonic Au-Ag nanostructures, copper chalcogenides and their hybrids with excellent optical properties tunable by their size, composition and structure. We have demonstrated the excellent plasmonic properties of these materials and systematically elucidated their structure-plasmonic property relationship. We also exemplified the applicability of these NIR-II optofunctional materials for SERS biosensing, photoacoustic imaging, CT, and light-assisted cancer therapy with excellent performance. We believe that these NIR-II plasmonic materials hold considerable potential for multimodality theranostics of cancer.
Nanoscale Amperometry Reveals Only a Fraction of Vesicular Serotonin Content Is Released during Exocytosis from Beta Cells
Authors: Hatami Amir
Published: July 2021

Recent work has shown that chemical release during the fundamental cellular process of exocytosis in model cell lines is not all or none. We tested this theory for vesicular release from single pancreatic beta cells. The vesicles in these cells release insulin, but also serotonin, which is detectable with amperometric methods. Traditionally, it is assumed that exocytosis in beta cells is all-or-none. Here we use a multidisciplinary approach involving nanoscale amperometric chemical methods to explore the chemical nature of insulin exocytosis. We amperometrically quantified the number of serotonin molecules stored inside of individual nanoscale vesicles (39317 ± 1611) in the cell cytoplasm before exocytosis and the number of serotonin molecules released from single cells (13310 ± 1127) for each stimulated exocytosis event. Thus, beta cells release only one-third of their granule content, clearly supporting partial release in this system. We discuss these observations in the context of type-2 diabetes. Finally, these data therefore raise the tantalising possibility that pharmacological intervention can be used to increase the fraction released during beta cell exocytosis and lead to new therapies for type-2 diabetes.
(Invited) Tailoring 2D Materials As Artificial Enzymes for Developing Electrochemical Biosensors
Authors: Ebrahimi Aida
Published: July 2021

There is a significant need for development of low-cost and portable diagnostics for non-invasive monitoring of biochemical markers. Among various biosensors, electrochemical sensors are at the forefront of point of care diagnostics, due to simple and real-time readout, low cost, high sensitivity, and portability, as evident from the dominance of enzymatic glucose sensors in the healthcare sector.(1) Despite their significant success, one of the main challenges with enzyme-based sensors is the limited (or none) choice of enzymes for analytes beyond glucose and their incompatibility with device engineering processes.(2)

Over the past few years, there have been significant advances in flexible sensors, printed electronics, and wireless devices based on graphene and other 2D materials.(2–5) Being atomically thin, with high surface-to-volume ratio, 2D materials are extremely sensitive to surface perturbation, making them suitable for highly sensitive and selective electrochemical sensors. Moreover, their physical, electronic, and electrochemical properties can be modified via doping, defects, and heterostructures to enable new functionalities for biochemical sensing. We have recently made significant progress in developing non-enzymatic electrochemical sensors based on 2D materials and hybrids as ‘artificial enzymes’, with special focus on device scalability and ease of fabrication. In this regard, we have studied the role of substrate in material-analyte interface characteristic,(6) the effect of post-deposition low-temperature annealing of 2D inks on material-analyte interaction, and the importance of defect configuration in tuning the material-analyte band alignment.(7) In this talk, I will present our recent progress and undergoing research in this area.

References:

C. Chen, et al., Current and emerging technology for continuous glucose monitoring. Sensors (Switzerland)
17, 1–19 (2017).

A. Bolotsky, et al., Two-Dimensional Materials in Biosensing and Healthcare: From In Vitro Diagnostics to Optogenetics and Beyond. ACS Nano, acsnano.9b03632 (2019).

S. Khan, S. Ali, A. Bermak, Recent developments in printing flexible and wearable sensing electronics for healthcare applications. Sensors (Switzerland)
19 (2019).

X. Zhang, et al., Two-dimensional MoS2-enabled flexible rectenna for Wi-Fi-band wireless energy harvesting. Nature
566, 368–372 (2019).

D. W. Park, et al., Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications. Nat. Commun.
5, 1–11 (2014).

A. Ebrahimi, et al., FeSx-graphene heterostructures: Nanofabrication-compatible catalysts for ultra-sensitive electrochemical detection of hydrogen peroxide. Sensors Actuators, B Chem. (2019) https:/doi.org/10.1016/j.snb.2018.12.033.

Y. Lei, et al., Single-atom doping of MoS2 with manganese enables ultrasensitive detection of dopamine: Experimental and computational approach. Sci. Adv.
6, eabc4250 (2020).