bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Relationship of Pseudo-Capacitive Current in Sulphuric Acid and Vanadium Flow Battery Reaction Kinetics at Carbon Electrodes
Authors: Al Hajji Safi Maria , Buckley D. Noel , Bourke Andrea , Lynch Robert P.
Published: February 2024

Flow battery technologies are promising solutions to the need for electricity storage driven by the increasing demand for energy supply at the same time as the electricity grid becomes more and more dependent on renewable sources such as solar, wind and ocean energy. Vanadium flow batteries (VFBs) are perhaps the most promising of these technologies and a growing number of commercial systems are in operation worldwide.

The energy efficiency of vanadium flow batteries (VFBs) largely depends upon the performance of the electrodes. Poor electrode kinetics cause large overpotentials, which reduce the voltage efficiency. They can also lead to side reactions, such as hydrogen evolution at the negative electrode and oxidation of the positive electrode, which reduce the coulombic efficiency and the overall performance and durability.

There is considerable variation in the data regarding the kinetics of vanadium redox reactions at carbon electrodes. We have previously reported that cathodic treatment enhances the kinetics of the positive (VIV-VV) electrode in VFBs but inhibits the kinetics of the negative (VII-VIII) electrode, while anodic treatment inhibits the kinetics of the positive electrode but enhances the kinetics of the negative electrode1-3. We also showed that the activity of carbon-based material is strongly dependent on the surface history, in particular the most positive and the most negative potential used to treat an electrode4. In this presentation we will further investigate the effect of electrochemical treatment of the carbon surface and show the relationship between the observed pseudo-capacitive behavior and the kinetics of the different vanadium redox couples.

References

Bourke, M. A. Miller, R. P. Lynch, X. Gao, J. Landon, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc.
163, A5097 (2016).

A. Bourke, M. A. Miller, R. P. Lynch, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc., 162, A1547 (2015).

M. A. Miller, A. Bourke, N. Quill, J. S. Wainright, R. P. Lynch, D. N. Buckley and R. F. Savinell, J. Electrochem.
Soc., 163, A2095 (2016).

M. Al Hajji Safi, A. Bourke, D. N. Buckley, R. P. Lynch, ECS Trans., 109, 67-84 (2022).
Expanding the Scanning Electrochemical Microscopy Toolset for Evaluating Electron Transfer Kinetics of Concentrated and Specialized Redox Electrolytes on Carbon Surfaces
Authors: Gaddam Raghuram , Qian Peisen , Rodriguez Lopez Joaquin
Published: February 2024

Performing quantitative measurements of heterogeneous electron transfer reactions at electrodes (e.g., determining k0 and a) under conditions of high redox active molecule concentration in solution, such as those encountered in electrolytes for redox flow batteries (RFBs), presents significant technical challenges. For example, attempting to use transient voltammetry methodology quickly leads to limitations imposed by iR drop, as currents can be large and resistance, especially in non-aqueous systems, can be high. Additionally, using steady-state techniques based on convective principles, such as the rotating disk electrode (RDE), involve the use of relatively large equipment, with moving parts, and usually with requirements of tens to hundreds of mL of solution, which may be limiting for exploring new compounds at high concentration.

To address these issues, here we introduce the use of scanning electrochemical microscopy (SECM) for the determining the rates of electron transfer of redox active species at high concentration in non-aqueous [1] and other unconventional systems, such as deep eutectic solvents. SECM enables the resolution of higher rates of electron transfer compared to transient voltammetry and RDE, and it also enables experiments with spatial resolution, enabling the exploration of reactivity on various sites of a heterogeneous electrode. In this presentation, we will describe theoretical and practical aspects of these measurements, and we will demonstrate their utility using two model systems. The first one consists on the observation of inherent rate asymmetries observed for ferrocene derivatives, ubiquitous redox probes, at the graphite/carbonate solvent interface. These asymmetries are not present on aqueous systems or metallic electrodes, demonstrating the ability of the SECM technique to capture unique behaviors. In the second case, we will discuss how SECM measurements can be used on deep eutectic solvents such as ethaline to address how interactions between redox actives and the electrode or the solvent systems modulate the rate of electron transfer. By systematically modifying the strength of interactions by means of molecule choice, solvent composition, and electrode type and structure, we can gain insight into the processes that determine reactivity at redox flow battery electrodes. This insight is critical for exploring the interfacial aspects such as adsorption, passivation, and double-layer effects on kinetics of electron transfer.

[1] Gaddam, R.; Sarbapalli, D.; Howard, J.; Curtiss, L.A.; Assary, R.S.; Rodríguez-López, J. An SECM-Based Spot Analysis for Redoxmer-Electrode Kinetics: Identifying Redox Asymmetries on Model Graphitic Carbon Interfaces Chem: Asian J., 2023, 18, 2, e202201120.

Figure 1
Nanoisland Formation on the Low Index Planes of Pt By Repeated Electro-Oxidation and-Reduction
Authors: Fuchs Timo , Schroefel Fabian , Fehrs Jan Ole , Merkel Nick , Kempf Simon , Bunge Jonas , Qiu Canrong , Harrington David A. , Drnec Jakub , Magnussen Olaf M.
Published: February 2024

Pt-based electro-catalysts are the most common cathode material in proton exchange membrane fuel cells given their high oxygen reduction reaction activity and stability. However, practical applications are limited by catalyst performance loss and degeneration. A main cause for this is nanoscale Pt surface restructuring, which occurs upon formation and reduction of a Pt surface oxide. During oxidation, a fraction of the Pt surface atoms are extracted in a process known as “place-exchange” from the electrode and are bound at specific sites in an oxide about 1 – 4 Å above the surface [1]. Upon subsequent oxide reduction, these atoms as well as the vacancies from which they originate can agglomerate, leading to the nucleation of adatom and vacancy islands. If this process is repeated, nanoislands with a well-defined lateral size of about 20 – 60 Å are grown [2-6]. Detailed studies of this growth process have been performed on the Pt(111) electrode [2-6], revealing two distinct growth regions which are characterized by different vertical scaling exponents [3].

For the development of catalysts with superior long-term stability, a more detailed knowledge of the restructuring of the other low index planes of Pt is required. In our recent study of the Pt oxides on Pt(111) and Pt(100) we already showed a strong dependence of the structural stability of the surface on differences in the atomic-scale oxide structure formed on those two surface orientations [1]. However, the influence of surface structure on the nanoisland growth after repeated oxidation and reduction is largely unclear.

We present a comparative operando grazing incidence small angle X-ray scattering (GISAXS) study of the nanoisland formation on Pt(111), Pt(100) and Pt(110) in acidic electrolyte. The GISAXS measurements of the nanoisland growth were performed at a high photon energy of >70 keV, which lowered background scattering from the electrolyte, enabling us to resolve the islands after the very first ox./red. cycle. Differences in island shape and growth behaviour on the low index planes will be discussed.

We gratefully acknowledge financial support by the Deutsche Forschungsgemeinschaft via project no. 418603497, MA 1618/23-1 and the BMBF via 05K19FK3.

References

Fuchs et al., Nat. Catal. 3, 754–761 (2020)

Sugawara and K. Itaya, J. Chem. Soc., Faraday Trans. 185, 1351-1356 (1989)

Jacobse et al., Nat. Mater. 17 (3), 277-282 (2018)

J. Rost, et al., Nat. Commun. 10, 5233 (2019)

Ruge et al., J. Am. Chem. Soc. 139, 4532 (2017)

Jacobse, et al. ACS Cent. Sci. 5 (12), 1920–1928 (2019)
(Invited) Molecular Imaging of the Local Solvation, Nucleation and Growth Processes at Electrode-Electrolyte Interfaces
Authors: Zhang Yingjie
Published: February 2024

Electrochemical energy storage is a complex process that requires the synergistic participation of electrodes, electrolytes, and separators in the system. However, the key energy storage functions usually depend critically on the electrode-electrolyte interfaces, which include both the electrode surface and the electrical double layers (EDLs). Here I will discuss our efforts on developing and using electrochemical 3D atomic force microscopy (EC-3D-AFM) to simultaneously image the electrode and EDLs under operando conditions, with atomic-scale resolution. We study the interface between graphite electrode and various types of electrolytes. We observe rich EDL reconfiguration effects at different electrode potentials, which we find to be directly responsible for the capacitive charge storage functions. As the electrode potential goes beyond the electrochemical stability window of the electrolyte, we observe nucleation and growth processes where the EDLs and the deposited solid clusters exhibit intertwined structures. Such initial stage of electrode processes is likely connected to the long-term cycling behaviors of batteries.
Solar Energy Is Effectively Converted to Electricity and Hydrogen Using Cyanobacteria
Authors: Lee Youngrok , Lee Jihhwan , Kim Sunghyun
Published: February 2024

We present solar energy conversion for electricity generation and hydrogen production from water using Anabaena variabilis (A. variabilis), an oxygenic photosynthetic cyanobacterium. Electrons from water oxidation by the light reactions that take place in thylakoid membranes (TMs) undergo a series of electron transfer pathway called Z-schme. We devised a method in which electrons are directed to the external electrode. In order to extract electrons from TMs, we found that double mediators are very effective in transferring electrons to the electrode from TMs. Dimethylbenzoquinone, the first mediator, can take electrons from the Z-scheme and delivers them to ferricyanide, the second mediator. Thus transferred electrons move to the cathode where oxygen reduction reaction takes place. Figure shows how biosolar cell (BSC) is operating under illumination.

Electricity generation was achieved by simply attaching an external load between the anode and the cathode. When A. variabilis was dispersed in solution, the maximum photocurrent up to 2.14 mA cm-2 upon one sun light intensity. A complete cell produced Pmaxof 160 mW cm-2 at 750 mA cm-2 with a quantum efficiency of 4.8% over a whole spectral range and turnover frequency of 17 per PSII for water molecule oxidation. The same concept was also applied to the hydrogen production. When operated in a double-chamber reactor under anaerobic condition, pure hydrogen gas was produced from water with high energy efficiencies and high production rates upon voltage bias. The maximum H2 production rate of 122 mmol H2(mg Chla)-1h-1 at anode potential of 0.4 V vs. Ag/AgCl was achieved. Energy efficiency exceeded 100% at lower anode potentials. We expect that this study opens a new way of utilizing cyanobacteria for appreciable electricity and hydrogen production. The same concept could be extended to other oxygenic cyanobacteria.

Figure 1
DFT Studies on Cun/TiO2 (n=1-7) System for Water Splitting
Authors: Tokarz-Sobieraj Renata , Kaipanchery Vidya , Drzewiecka-Matuszek Agnieszka , Rutkowska-Zbik Dorota
Published: February 2024

Copper deposited on titania is active in numerous catalytic reactions, incl. water splitting [1]. The activity of the system depends on the size of the copper phase, whether it is present as single atoms, sub-nanometer clusters, or nanoparticles.

The aim of the current contribution is to elucidate the relationship between the size of the copper active phase and its electronic and geometric properties by performing Density Functional Theory (DFT) calculations with PBE functional and the def2-TZVP basis set.

Theoretical model of the system comprised of a cluster model of anatase phase of titania – (TiO2)34 - with clusters of copper of varying sizes on top of it. The ground-state geometric and electronic structures were elucidated. Next, their redox and photochemical properties were determined: frontier (HOMO, LUMO) orbitals were defined, energy gaps, total and partial density of states were plotted and analysed. The interactions between components of the systems, in particular the influence of the support on the copper electronic structure, were investigated. Next, the reactivity of the metal phase towards typical intermediates observed during water splitting (H2O, OH, O, and H) was studied.

The performed calculations demonstrated that the presence of metal determines the energetics and character of the frontier orbitals of the catalyst. The size of copper active phase influences the bond lengths and bond orders with studied reagents.

Acknowledgements: This work was supported by the National Science Centre, Poland within Solar-Driven Chemistry project no 2019/01/Y/ST4/00024. This publication is based upon work from COST Action CA 18234 “Computational materials sciences for efficient water splitting with nanocrystals from abundant elements”, supported by COST (European Cooperation in Science and Technology). We gratefully acknowledge Polish high-performance computing infrastructure PLGrid (HPC Centers: ACK Cyfronet AGH) for providing computer facilities and support within computational grant no. PLG/2020/013927.

Literature:

[1] Cheng Cheng, Wei-Hai Fang, Run Long, and Oleg V. Prezhdo, JACS Au 2021, 1, 5, 550–559
(Digital Presentation) Perovskite-Type Lanthanum Ferrite Synthesis Using Industrial Sugarcane Molasse and Its Application in Electrochemical Detection of Acetaminophen
Authors: Castellanos Bernal Cindy Vanessa , Morales Jimmy , Alfonso Guillermo , Granja Claudia Patricia , Dector Andrés , Gómez Cuaspud Jairo Alberto
Published: February 2024

Perovskite-type lanthanum ferrite nanoparticles were developed and used to detect acetaminophen. For this work, lanthanum ferrite nanoparticles were synthesized by the combustion technique using industrial sugar molasses with lanthanum nitrate and ferric nitrate. To verify the electrochemical properties of an electrode modified with these perovskites, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used. During the experiment, phosphate buffer solution was used. Preliminary tests will show promising results on the electrocatalytic effect of lanthanum ferrrite obtained from a synthesis assisted with molasses of industrial origin.
(Digital Presentation) Green Synthesis of Calcium Ferrite Particles and Preliminary Study of Their Application for Electrochemical Detection
Authors: Gómez Lara Kevin Steven , Morales Jimmy , Alfonso Guillermo , Granja Claudia Patricia , Dector Andrés , Gómez Cuaspud Jairo Alberto
Published: February 2024

This work presents results of the synthesis of mixed metal oxides such as calcium ferrite by dissolving Ca(NO3)2.4H2O, Fe(NO3)3.9H2O and NH4OH with constant stirring, and assisted with conventional heating or microwave (MAE) combustion. using natural aloe vera extract as fuel at 900°C for 3 hours. The resulting material was characterized by instrumental methods for powders. Calcium ferrite powders were used for the modification of the surface of a glassy carbon electrode. The modified electrodes were used for the electrochemical investigation of acetaminophen (ACe) and acyclovir (ACy), at controlled pH. The preliminary results demonstrated the potential application of calcium ferrite powders in the electrochemical detection of molecules of pharmaceutical interest.
Error-Aware, Layer-Resolved Characterisation of Lithium-Ion Batteries Based on Ultrasonic Resonance and Parametric Analysis
Authors: Ren Yuankai , Huang Ming , Patel Yatish , Cegla Frederic , Lan Bo
Published: February 2024

With the prevalence of electrification in transportation and grid storage sectors, lithium-ion batteries (LIBs) are becoming one of the most fundamental energy storage elements and undergoing a profound trend of performance upscaling. The upscaled batteries demand next-level characterisation methodologies, and particularly appealing is the capability to resolve inner structural and morphological information physically, so as to identify the internal state and evolutions precisely and cost-effectively. In recent years, ultrasonic measurements have been proven as promising candidates for probing and inspecting LIBs. However, such approaches can only measure peripheral geometric features at a cell-level resolution and their characterisation performances tend to be subject to empirical configurations and sensitive to measurement conditions. To address these issues, this work reports an ultrasonic resonance-based method, featuring reliable characterisation performance, to realise layer-level robust inversion of the layered structure within LIBs. Firstly, a generalised theoretical model is introduced to capture the interaction characteristics between the ultrasound and the multilayer structure inside LIBs. By incorporating the captured characteristics into the analytic-signal procedure, a systematical framework is established to retrieve the stacking order, individual thickness, and local geometry information in a layer-resolved manner1, 2. Then, the relationship between the measurement parameters and the characterisation performance is analytically investigated. By considering both the temporal and spatial metrics, the performance evaluation indices are determined, with the critical measurement parameters recognised according to their physical significance. After that, the impacts of measurement parameters on the characterisation performance of LIBs are thoroughly studied by carrying out parametric analysis on the response signal simulated by the ultrasonic resonance model. Guided by such a relationship, an optimal strategy for parameter selection is developed to ascertain reliable characterisation, with its level of errors being predictable. Finally, experimental studies are carried out on different batteries with the ground truth obtained by the micro X-ray computed tomography, and the effectiveness and reliability of the proposed characterisation method are carefully validated. The proposed method demonstrates reliable performance in characterising layered structure within LIBs and could pave the way for developing performance-informed monitoring and prediction algorithms for state of health and state of safety estimations of LIBs.

References

M. Huang, N. Kirkaldy, Y. Zhao, Y. Patel, F. Cegla, and B. Lan, Journal of Energy Storage,
50 104585 (2022).

R. A. Smith, L. J. Nelson, M. J. Mienczakowski, and P. D. Wilcox, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control,
65 (2), 231-243 (2018).
Cerium Ion Adsorption to Fluorine-Doped Tin Oxide Electrodes
Authors: MacInnes Molly M
Published: February 2024

The f-elements are critical in many technologies including electronics, catalysis, magnetics, and clean energy. Additionally, these elements occur in very low abundance worldwide. Research has therefore been motivated in the detection, quantification, and reclamation of these elements from waste streams. In this presentation we explore the use of fluorine-doped tin oxide (FTO) electrodes as sensitive and cost-effective electrochemical sensors for cerium ions. We demonstrate that cerium adsorbs reversibly to bare FTO surfaces with a dependence on pH. Through voltammetry and XPS characterization, we demonstrate that the adsorbed cerium, which can undergo the quasi-reversible CeIV/CeIII redox transition, exists in more than one chemical environment. Based on these data, we posit that these different environments are due to the buildup of multiple layers of cerium ions on the FTO surfaces. At lower concentrations (< ca. 100 uM), we can use voltammetry to quantify the cerium adsorbed to the FTO and relate it to the concentration of cerium in solution, with a lower detection limit of about 10-6 M. The data fits to a pseudo second order rate law with a rate constant on the order of 107 (cm2 mol-1)2 s-1. The adsorption fits well to the Freundlich model, but we are working towards finding a non-empirical adsorption model than provide the equilibrium constant for the adsorption reaction.
Development of Electrochemical Paper-Based Devices for Field Assays
Authors: Economou Anastasios , Kokkinos Christos , Soulis Dionysios , Pagkali Varvara , Prodromidis Mamas
Published: February 2024

The birth of the modern field of paper-based analytical devices (PADs) was marked by the pioneering work by the Whitesides’ group which demonstrated that it was possible to perform complex manipulation of liquids within hydrophilic paper channels delimited by hydrophobic barriers [1]. The key features of paper as a platform are: a) flexibility; b) low thickness and lightness; c) absorbency; d) high surface-to-volume ratio; e) hydrophilicity and capillary action; f) chemical and biological inertness; g) disposability and biodegradability, and; h) low cost and wide availability. Among the various detection modes that are compatible with PADs, electrochemical detection is very attractive since electrochemical transducers can be readily and rapidly patterned on paper using various approaches. Combined with low-cost and portable instrumentation, electrochemical PADs (ePADs) are well suited to on-site assays and point-of-care testing and relevant applications have been developed in various fields such as clinical diagnostics, environmental monitoring and food quality control [2-4].

The methods of patterning of the hydrophobic barriers and of depositing the electrodes are critical in the fabrication of ePADs and several approaches have been proposed in the literature [2-4]. Τhe aim of this work was the development of different approaches for the fabrication of ePADs. For this purpose, hydrophobic barriers were delimited using: x-y plotting with commercial hydrophobic marker pens, wax printing and thermal printing. Electrodes were deposited on the PADs using x-y plotting with commercial writing pencils and conductive inks formulated in-house and screen-printing. Different fabrication parameters were optimized including the selection of the paper substrate, the conditions for the formation of the hydrophobic barriers and the electrode deposition parameters. Applicability of the ePADs was demonstrated for different applications for on-site assays including the enzymatic amperometric detection of glucose, the determination of trace metals by stripping analysis and the voltammetric detection of organic compounds.

References

[1] A.W. Martinez, S.T. Phillips, M.J. Butte, G.M. Whitesides, Angew. Chem. Int. Ed. 2007, 46, 1318.

[2] E. Noviana, C.P. McCord, K.M. Clark, I. Jang, C.S. Henry, Lab Chip 2020, 20, 9.

[3] V.N. Ataide, L.F. Mendes, L.I.L.M. Gama, W.R. de Araujo, T.R.L.C Paixao, Anal. Methods 2020, 12, 1030.

[4] W. Mazurkiewicz, M. Podrażka, E. Jarosińska, K. Kappalakandy Valapil, M. Wiloch, M. Jönsson-Niedziółka, E. Witkowska Nery, ChemElectroChem 2020, 7, 2939.

Acknowledgements

This work was funded by the Hellenic Foundation for Research and Innovation under the “3rd Call for Scholarships for PhD Candidates”.
Robust Type III Potentiometric Sensors for SOx Realized Via Fast Solid-State Potassium Ion Conductors
Authors: Khoshkalam Mohamad , Holtappels Peter , Sudireddy Bhaskar Reddy
Published: February 2024

Sulfur oxide gases (SOx) are among the most serious air pollutants that contribute to acid rain and have a significant impact on human health and the environment. The sensing and quantification of SOx is critical for industrial and environmental applications, such as monitoring air quality, controlling emissions from power plants and maritime vessels, as well as ensuring safety in industrial processes. However, conventional sensing methods are limited by prohibitive costs, complex hardware, and maintenance requirements. In this work, we present a novel potentiometric type III solid-state sensor for the sensing of SOx using fast and ambient stable potassium-ion (K+) conducting solid-state electrolytes (KSE). Several potentiometric sensors including (O2,Au|Ag|KSE|K2SO4|Pt|Au,SO2,O2), (O2,Au|Ag|KSE|K2SO4+LaNi0.6Fe0.4O3|Pt|Au,SO2,O2) and (O2,Au|Ag|KSE|LaNi0.6Fe0.4O3|Pt|Au,SO2,O2) were assembled and characterized by chronopotentiometry. This is the first demonstration of a type III potentiometric SOx sensor using solid-state K+ conductor, operational while both sensing and reference electrodes exposed to same gas mixture without the need for sealed and separated gas chambers. The sensors in this study, at 0-10 ppm SO2 concentration and temperature range of 300-500 ℃, exhibited high sensitivities (74-89 mV/dec), robust signal output (as high as 600 mV for 2 ppm of SO2), fast response times (as low as 2 minutes), and excellent stability in ambient condition. These sensors also demonstrated good selectivity towards SOx over other interfering gases such as CO2. The results of this study indicate that the proposed sensor has immense potential for technological applications such air quality monitoring in maritime applications.

Figure 1
Characterization of a Waveguide with 45 Degrees Reflectors for the Detection of Carbon Dioxide
Authors: Lee Junyeop , Hwang Seongpil , Bang Narae , Jung Dong Geon , Jung Daewoong
Published: February 2024

This paper investigates the characteristics of the angle of incidence of a waveguide with 45 degrees reflectors. Non-dispersive infrared (NDIR) gas sensors consist of an infrared source, a waveguide, and an infrared detector. The waveguide especially plays a part in an infrared path and gas cell. According to the Beer-Lambert law, the NDIR sensor with longer ray traveling path shows a higher response to the target gas. Also of particular interest is that the normal incidence ratio toward an infrared detector enhances the NDIR sensor selectivity for the target gases as well as the sensitivity. While there has been significant research on the effect on sensitivity by designing waveguide structures or ray traveling distance, this paper focuses on understanding the incidence of light toward the infrared detector by the waveguide with 45 degrees reflector and how this affects the selectivity of the sensor. A Ray tracing simulation is adopted to analyze the effect of the number of 45 degrees reflectors on the distribution of the incidence. Furthermore, a non-dispersive infrared gas sensor is applied to measure how the number of the reflectors affect to the selectivity for the target gas. The results reveal the enhancement of the selectivity by the reflectors.

Acknowledgements

This work was supported by the Korea Innovation Foundation(INNOPOLIS) grant funded by the Korea government(MSIT) (2020-DD-UP-0348). This study has been conducted with the support of the Korea Institute of Industrial Technology as "Development and commercialization for clean hydrogen production/storage and CO2 monitoring system in the field of industrial complex" (Kitech EH-23-0012) This work was supported by the Technology Innovation Program (155736, Development of Miniaturized Sensor Module Technology for Non-invasive Arterial Blood Carbon Dioxide Real-time Monitoring) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea).

Figure 1
Blood Cell Detection Method Using Single-Entity Electrochemistry
Authors: Kim Byung-Kwon
Published: February 2024

The study of single-entity electrochemistry on ultramicroelectrodes, also known as Nano-impact electrochemistry or Single-particle collision, has recently gained attention. This method allows for the analysis of various properties of particles in solution, such as diffusion coefficient, particle composition, size distribution, and concentration. Our group has also explored the use of this technique on soft entities like emulsions, bacteria, red blood cells, and platelets. By monitoring the increase or decrease in current signal when a single-entity collides with the electrode surface, we can gain insights into the properties and composition of the particles. For example, if there is a high concentration of redox constantly reacting in the UME and red blood cells collide with the electrode surface, we can observe a decrease in the current. As another example, when platelets collide with electrodes, the concentration of serotonin present in platelets can be analyzed. In this case, an increase in the current signal is observed. The increase or decrease of the current signal depends on the characteristics of the single-entity and the composition of the solution. As such, single-entity electrochemistry is a useful way to obtain important information about various entities.
(Digital Presentation) A Novel Method for Precise Measurement of Displacement Using Eddy Currents at High Temperature
Authors: Kwon Ikhyun , Kim Cheong Worl
Published: February 2024

In this paper, a novel method of measuring displacement using eddy currents at high temperature is presented. The measurement system consists of a sensing coil created on a PCB by patterns, a parallel turning circuit and a microcontroller including a signal processing unit. When the gap distance between the conductive target and the sensing coil changes, the inductance value of the coil varies by the influence of the eddy current. By detecting the change in the inductance, we have proposed a novel method to precisely measure the displacement of the coil. In order to make the optimal coil, a theoretical analysis was conducted using the inductance calculation theory, and the magnetic field distribution and inductance variation of the coil were analyzed using ANSYS Maxwell. Then, the coil was fabricated as a PCB, and the measured result value was compared with each analysis result, and the coil most suitable for the system was selected. The circuit was designed so that the characteristics of the synchronization amplification circuit in the detection system were minimized in temperature change, and the temperature characteristics were primarily corrected in hardware by adding a temperature correction circuit. The output value of the primarily corrected tuning amplification circuit improved the temperature characteristics of the sensor by secondarily correcting the temperature characteristics in firmware, and is designed to meet the IPC class 3 specification. The sensing range of the implemented measurement system was 0.0 ~ 3.8 mm, the nominal value of the fabricated sensing coil was 11.2uH, and the resonance frequency of the tuning circuit including the sensing coil was 300Khz. The operating temperature of the system is – 40 ~ 150 ℃ and the resolution is 0.15 mm within the range of 0.0 ~ 3.8 mm. From the experimental results, Comparing the change in inductance with respect to the moving distance of the measurement system and the displacement signal measured by the system, it can be seen that as the inductance increases, the displacement output increases, and as the inductance decreases, the displacement also decreases. Considering this, it was found through the system that inductance and output of displacement are correlated, and is seen operates stably at high temperature and has linearity.

Figure 1
(Invited) Real Time Monitoring of Target Binding for the Development of Clinical Diagnostic Tests
Authors: Soleymani Leyla , Li Yingfu , Sen Payel , Zhang Zijie
Published: February 2024

Currently, there is tremendous interest in developing continuous monitoring systems for better managing health and disease. These platforms rely on readout methods that continuously monitor the presence of bioanalytes in physiological matrices. In this talk, I will discuss the development of new electrochemical signal readout methods that continuously monitor the binding of targets with biological recognition elements such as functional nucleic acids. We will discuss the application of these platforms to the detection of infectious pathogens as a model system, but will show the possibility of its extension to protein targets.
Gradient Porous Graphene-Based Ion-Selective Electrode for Real-Time Monitoring of Sweat Electrolyte
Authors: Gao Zhaoli , Yeung Kan Kan
Published: February 2024

Human sweat, a biomarker-rich physiological fluid, is an ideal candidate for non-invasive and real-time health monitoring. State-of-the-art electrochemical sweat sensors, that detect concentrations of analytes, such as electrolytes, through ion-selective membranes (ISM) in ion-selective electrodes (ISEs), show great potential for monitoring bodily conditions with high selectivity and affordability. Ion detection can be accomplished by utilizing the electrochemical potential gradient across an ISM within the solid-contact ISE. The solid-contact interface, located between the sensing membrane and electron-conducting substrate, plays a crucial role in ion-to-electron transduction. This critical layer serves to minimize the formation of the water layer, enabling stable potential responses and maintaining long-term stability.

This work focuses on the use of chemical vapor deposition-grown, hydrophobic, gradient porous graphene (3D-G) material as the solid-contact layer in the ISE, offering a wider detection range, enhanced sensitivity, and improved long-term stability. The highly porous structure promotes ion recognition, diffusion, and adsorption onto the enhanced electrode surface, resulting in long-term stability, rapid analyte diffusion, and enhanced ion-to-electron transduction for sweat electrolyte sensing. A three-dimensionally interconnected porous electrode design can significantly enlarge the sensing areas in comparison to a 2D planar electrode, thereby improving the overall sensing performance of the sweat sensor. Owing to their large interface area, coupled with large double-layer capacitance in all-solid-state ISEs, hydrophobic nanostructured materials have been demonstrated to facilitate the ion-to-electron transduction process. Employing the 3D-G ISEs for health assessment has been exemplified through an on-body sweat sensing experiment, wherein the obtained results exhibit notable similarity with those generated by Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

Figure 1
(Invited) Electrochemical Microbiosensors for Real-Time Monitoring of Reactive Oxygen Species in Living Tissues
Authors: Andreescu Emanuela
Published: February 2024

Understanding fundamental mechanisms involved in the progression and development of diseases is of great physiological and pathological importance. Such studies require the availability of effective methods to probe biochemical processes in real time and allow accurate detection and quantification of biomarkers and mediators of injury. Study of the role and mechanism of action of these mediators is also critical to develop therapies and assess pharmacological effects. However, the presence of these chemicals at very low concentrations and variable levels and the complexity of the biological environment pose a great challenge for their detection. Using custom designed microelectrodes, electrochemistry provides unique opportunities to detect reactive species in living tissues, providing direct and real time evidence of reactive oxygen (ROS) levels with high spatial resolution. This presentation will discuss our efforts to fabricate microbiosensing platforms for investigating fundamental physiological and biochemical mechanisms in vivo and in vitro, particularly those associated with ischemia and reperfusion injury. The influence of the microelectrode design parameters including surface coatings and electrode size, and the ability of the sensor to obtain quantitative spatial and temporal analytical data of the release and distribution of oxidative stress markers will be provided with examples of applications. Advantages and limitations of these systems for measurements in real biological environments will be discussed. Our results demonstrate the potential of electrochemical techniques to generate information about biomarkers and obtain fundamental biochemical-relevant information on physiology, metabolism and disease states in living systems.
(Invited) Emissive Transition-Metal Complexes and Their Applications for Optical Sensing and Bioimaging
Authors: Sun Wenfang
Published: February 2024

Phosphorescent transition-metal complexes, such as the Pt(II) and Ir(III) complexes are attractive candidates for optical sensing (including biosensing) and bioimaging applications due to their long-lived emission that can avoid the interference from the autofluorescence of biosystems. By selecting appropriate ligands and incorporating different functional groups to the ligands, the emission color, intensity, and lifetime can be readily tuned. We have synthesized various red to near-IR emitting Pt(II) and Ir(III) complexes that can be potentially used as biosensing and bioimaging materials.
(Invited) Towards Self-Powered Biosensing
Authors: Minteer Shelley D.
Published: February 2024

Amperometric biosensors are highly sensitive and selective, but for some applications, it is challenging that amperometric sensors require a potentiostat and a power source. This talk will discuss the translation of amperometric biosensors to self-powered biosensors for wearable devices by combining analyte sensing bioanodes with oxygen consuming biocathodes. This paper will discuss the enzyme and materials challenges that need to be addressed during the translation from amperometric biosensors to self-powered biosensors.
(Invited) Skin-Interfaced Wearable Biosensors
Authors: Gao Wei
Published: February 2024

The rising research interest in personalized medicine promises to revolutionize traditional medical practices. This presents a tremendous opportunity for developing wearable devices toward predictive analytics and treatment. In this talk, I will introduce our efforts in developing wearable biosensors for non-invasive molecular analysis. Such wearables can autonomously access sweat across activities and continuously measure a broad spectrum of analytes including metabolites, nutrients, hormones, and drugs. Laser-engraving and inkjet printing are used to manufacture these nanomaterials-based biosensors at large scale and low cost. The clinical value of our wearable systems is evaluated through human studies toward metabolic & nutritional monitoring, disease diagnosis, mental health assessment, and drug personalization. I will also discuss our research progress on energy harvesting from the body fluids and human motion to realize battery-free wireless wearable sensing. These wearable technologies could open the door to a wide range of personalized monitoring, diagnostic, and therapeutic applications.
Tandem Affinity Purification of FITC-Labelled Target Protein for Biomedical Applications
Authors: Bose Kakoli
Published: February 2024

Fluorescence-based assays are dynamic, sensitive and robust quantitative methods for studying the conformational plasticity, enzyme kinetics, dynamics, and macromolecular interactions. However, the caveat for most of these experimental approaches is to label the target protein with one or more extrinsic fluorophores having required photophysical characteristics. Fluorescein isothiocyanate (FITC), due to its high quantum efficiency and conjugate stability, is most widely used fluorescence labelling reagent for such experimental approaches. However, the limitations in this method are requirement of high protein concentration, maintenance of protein stability during the entire labelling process as well as presence of significant background fluorescence due to ineffective removal of unreacted FITC. Therefore, to circumvent these setbacks, we have devised a novel strategy through introduction of tandem affinity purification tags at both the N- and C-termini of the protein of interest. Using this method, we have efficiently labelled target protein with significant decrease in precipitation, degradation and background fluorescence due to residual FITC. This facile and rapid technique may also be used as a basis for labelling procedures with other fluorophores and hence has a broad application in the field of biomedical sciences.

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(Invited) Biosensing for Biomanufacturing of Therapeutics
Authors: Wang Junhyeong , Hosseini Mahshid , Ismail Irfan , Barbieri Eduardo , Shastry Shriarjun , Ritola KImberly , Menegatti Stefano , Daniele Michael
Published: February 2024

Contemporary process analytical technologies (PATs) for biomanufacturing are available for continuously monitoring a small set of analytical targets or are limited by costly and time-consuming offline efforts, which require extensive bioseparation, sample conditioning, and reagent handling. With the prime focus of the biopharmaceutical industry crystallizing around monoclonal antibodies and cell/gene therapies and the need for nimble, efficient production platforms, it is more relevant than ever to create scalable, in-line, and high throughput quantification methods to interrogate and direct the control of complex, stochastic processes during a production run. To realize such capabilities, there is a unique opportunity to "steal" from the extensive body of research and development in biosensors and assays for mobile diagnostics. In this lecture, I will assess the unique challenges that that arise in re-designing biosensors to meet the needs of online/in-line analytics in biomanufacturing and present examples of our research in the integration of microfluidics and electrochemical sensing for viral vector and other biologics production.
(Invited) Luminescence Nanothermometers: Using Light to Detect Temperature
Authors: Vetrone Fiorenzo
Published: February 2024

Rare earth doped nanoparticles have recently emerged as versatile luminescent probes for a number of biological applications resulting from their interesting photophysical properties. These nanoparticles can be excited with near-infrared (NIR) light, which is a strict requirement for biomedical applications due its light penetration capabilities. Furthermore, rare earth doped nanoparticles possess a multitude of 4f electronic energy states and excitation with NIR light can therefore lead to different excitation mechanisms. For example, following NIR excitation, the nanoparticles can undergo upconversion where multiple emissions are observed with energies higher than the excitation wavelength. Also, they can undergo conventional luminescence where emission at lower energies than the excitation wavelength can be observed (known as downshifted luminescence). Here, we show that it is possible to harness these various emissions (upconverted and downshifted) to design luminescence nanothermometers capable of detecting temperature in living organisms.
(Invited) Sustainable Paper Substrates for Biosensor Development
Authors: Mitra Sushanta
Published: February 2024

Paper substrates are becoming a sustainable material for various applications related to the rapid monitoring of different analytes. Capillary forces within the paper's pores can be used to manipulate the transport of different chemicals and target analytes. We have used paper strips to detect E. coli in contaminated water. An enzymatic reaction is conducted on the paper substrate, and it provides a colour change in the presence of water-borne pathogens. Like pathogens, another growing concern is the amount of pesticides in water. We have developed a novel device, “Dip-and-Fold”, which detects pesticides, such as carbamates and organophosphates, via Ellman’s acetylcholinesterase (AChE) inhibition method. This technology is user-friendly and does not need any extra steps for adding reagents. Towards the fight against COVID-19, a sustainable technology based on a paper strip with conjugated nanoparticles and aptamers is discussed. Finally, such lateral flow assays can be used for detection of tuberculosis in limited resource communities.
Cellulose Nanocrystals As a Key in Wearable Sensors
Authors: da Fonseca Jessica Heline Lopes
Published: February 2024

In recent years, the development of cellulose-based inks for 3D printing has received significant interest due to numerous cellulose and its derivatives properties [1], [2]. Carboxymethyl cellulose (CMC) is an anionic water-soluble cellulose derivative widely used as superabsorbent hydrogels [3]. Another cellulose derivative is cellulose nanocrystal (CNC), a rod-like nanoparticle that can be applied for the mechanical strengthening of hydrogels and also presents potential use in several applications in the biomedical field [2], [4]. Based on this, we have proposed to investigate if CMC and CNC mixtures result in cellulose-based nanocomposite gels suitable for extrusion printing of wearable sensors. Interactions between CNC and CMC resulted in physical gels, where rheological properties and extrusion printing parameters' effects were studied. A Modular Compact Rheometer (Anton Paar MCR-102, Austria) with a plate-plate geometry (50 mm diameter and 1 mm gap) at 25 °C was used to perform rheological measurements. Extrusion printing was performed on the customized 3DCloner Lab printer using a 22G nozzle tip of 25 mm in length and a diameter of 0.70 mm (Injex, Brazil). Gels presented shear-thinning, solid-like viscoelastic behavior, viscosity recovery, and continuous filaments obtained during printing. Moreover, the alignment of rod-like CNC during the printing process can be a key to improving properties. Tests with different print and extrusion speeds evidenced the influence of the wearable sensor's geometry and mechanical properties. Moreover, the low cytotoxicity of CMC/CNC crosslinked hydrogels was confirmed through an MTT assay of fibroblasts. Further testing is being conducted to evaluate the self-healing and conductive properties of the sensors by external stimuli. Moreover, low cytotoxicity to CMC/CNC crosslinked hydrogels was confirmed through an MTT assay of fibroblasts. External stimuli are being applied to evaluate the self-healing and conductive of the sensor printed.
Applications of Optical Method As an Effective Platform for Progesterone Sensing Using Carbon Dots and Graphene Oxide
Authors: Disha Disha , Kumari Poonam , Rani Raj , Nayak Manoj Kumar
Published: February 2024

Today, ‘Hormonal imbalance’ is a significant concern worldwide that lead to various types of complications in human body. For instance, abnormal levels of steroid hormones, such as progesterone are associated with irregular or absent menstrual periods, reproductive disorders, infertility, cardiovascular diseases, and cancer. Nowadays, progesterone is being excessively consumed as oral contraceptives, menopausal hormone therapy and treating infertility, resulting into the deleterious effects due to its endocrine disrupting activity. Furthermore, its presence as a potent endocrine disruptor in surface or environmental waters and various daily use products is another concern. Therefore, monitoring progesterone hormone is vital in environmental samples because of the adverse effects on reproductive health and causing hormonal imbalance. Herein, we have developed optical photoluminescence (PL) method implementing carbon dots (CDs) and graphene oxide (GO) based fluorescence resonance energy transfer (FRET) mechanism for progesterone hormone sensing. In this method, firstly progesterone-specific antibodies are covalently functionalized to CDs whose fluorescence has been quenched (turn off) by adding GO. However, the presence of progesterone increases the distance between donor and acceptor moieties and turns-on the fluorescence by displacing GO off the surface of CDs which in turn substantially reduces the FRET efficiency. Various optimization steps have been performed under control experiments to tune the fluorescence of CDs and the concentration of graphene oxide for maximum efficiency. In conclusion, a linear relationship is achieved in between PL intensity and different progesterone concentrations (10-900 nM) with 13.8 nM detection limits (R2=0.974). The structural and morphological analysis (XPS, and FT-IR) revealed the structural and surface functionalities of CDs. Finally, the potential of the developed biosensor has been explored in water matrices.