PURPOSE: Carcinoma in situ is an aggressive form of bladder cancer with a high propensity for invasion if left untreated. On cystoscopy these flat lesions cannot be differentiated from other erythematous, potentially benign areas and they require biopsy for definitive diagnosis. Other methods of detecting carcinoma in situ remain experimental. We assessed the effectiveness of electrical impedance spectroscopy, a method that measures the variation of electrical current flow with frequency through the mucosa, for differentiating various pathological changes in the urothelium. MATERIALS AND METHODS: We obtained 250 impedance measurements immediately after resection in 35 cystectomy specimens using a custom designed probe. Three consecutive readings were recorded per point to assess reproducibility and punch biopsy was done at the measurement site. RESULTS: Changes in the urothelium were classified histologically into 7 subgroups according to the degree of edema and inflammation. Electrical impedance
Background Previous studies have shown statistically significant differences in electrical impedance between various cutaneous lesions. Electrical impedance spectroscopy (EIS) may therefore be able to aid clinicians in differentiating between benign and malignant skin lesions. Objectives The aim of the study was to develop a classification algorithm to distinguish between melanoma and benign lesions of the skin with a sensitivity of at least 98% and a specificity approximately 20 per cent higher than the diagnostic accuracy of dermatologists. Patients/Methods A total of 1300 lesions were collected in a multicentre, prospective, non-randomized clinical trial from 19 centres around Europe. All lesions were excised and subsequently evaluated independently by a panel of three expert dermatopathologists. From the data two classification algorithms were developed and verified. Results For the first classification algorithm, approximately 40% of the data were used for calibration and 60% for testing. ...
A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonation process can be quantitatively accessed by a parameter, which can be obtained by means of the electrochemical impedance spectroscopy (EIS)-based electrochemical model. It has been found that the parameter is a function of carbonation depth and of carbonation time. Thereby, prediction of carbonation depth can be achieved.
Soleimani, M. and Estrela, P., 2009. Miniaturised electrical impedance spectroscopy tomography (EITS) for single cell imaging: A simulation study. In: First Bio-Sensing Technology Conference, 2009-11-10 - 2009-11-12.. ...
In this paper, the behavior of the salicylate anion-selective electrode was studied using the electrochemical impedance spectroscopy technique. Considering the diagram of the charge transfer resistance and -logarithm of the double layer capacitance versus -logarithm of the concentration, linear range concentration increased to 1.0×10^{-8}-1.0×10^{-1} M and 1.0×10^{-9}-1.0×10^{-1} M, respectively. Among the other characteristics of this study, it can be pointed out a wide pH range of 4.0-10.0. Then one-impedance for one-concentration method was used to measure the salicylate ion at the linear range of 1.0×10^{-8}-1.0×10^{-1} M. Finally, the impedance spectra of this electrode were simulated in which the obtained results of this simulation indicate proximity of experimental and simulation data.
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Electrochemical impedance tests were applied to steel specimens which were coated by epoxy and tested after immersion in Dead Sea water for different periods at room temperature and at 50C. Results taken from Nyquist and Bode plots and as were analyzed by means of software provided with the instrument. Results were presented as the values of capacitance and resistance (Cdl and Rct). Results show that degradation occurred after immersion in the test solution, and were more severe at higher temperature. Specimens were examined under scanning electron microscope, and micrographs showed clear rupture and degradation in epoxy coatings.
p,This paper describes the development of a low-cost, miniaturized, multiplexed, and connected platform for dielectric impedance spectroscopy (DIS), designed for in situ measurements and adapted to wireless network architectures. The platform has been tested and used as a DIS sensor node on ZigBee mesh and was able to interface up to three DIS sensors at the same time and relay the information through the network for data analysis and storage. The system is built from low-cost commercial microelectronics components, performs dielectric spectroscopy ranging from 5 kHz to 100 kHz, and benefits from an on-the-fly calibration system that makes sensor calibration easy. The paper describes the microelectronics design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the testing of the platform for in situ dielectric impedance spectroscopy applications pertaining to fertilizer sensing, water quality sensing, and touch sensing. ,/p,. ...
In addition to the two parallel plate electrodes (denoted as Counter and Working electrode), a third voltage reference electrode is placed close to the polarization layer and measures the voltage difference of the polarization double layer capacity to the working electrode. In contrast to dielectric, conductivity and impedance material spectroscopy where all electrodes are made of inert metal as e.g. gold, stainless steel or platinum, this applies for the electrochemical cell only for the counter electrode feeding current into the electrolyte.. The working electrode consists of the metal to be characterized in combination with the electrolyte. The reference electrode is usually an open tipped glass capillary filled with a standard electrolyte coupled to a standard metal in order to create a defined electrochemical potential to the electrolyte.. The total potential drop across the cell is summed up by all contributions of the chemical process like mass transport, chemical and adsorption steps, ...
Development of a micromachined electrode array for cochlear implant application is presented. The device is constructed from a silicon substrate with sputtered platinum electrodes and connection tracks. Electrochemical impedance spectroscopy (EIS) is used to study the properties of the electrode, and to identify potential problems caused by the micromachining process and materials. A variety of insulators are studied and a two part epoxy is identified as an adequate insulator for operation under harsh electrochemical testing conditions. The semiconducting silicon substrate is found to contribute to the total impedance of the device at high frequencies due to the thin insulating oxide between the substrate and conducting tracks. This is a potential problem for micromachined electrodes operating under high frequencies or using square stimulating pulses. The charge-delivery properties are studied using electrochemical impedance spectroscopy. It is found that platinum sputtered under particular ...
Despite the fact that spins ,1/2 (quadrupolar nuclei) give asymmetric lines, even if the materials are very ordered (depending on the local symmetry of the electronic cloud around the nuclei; in practice a lot of local disorder may result in more symmetrical lines because of distribution of local environments), the broad and asymmetrical shape of the NMR signal of 27Al produced by the MK used for the mixes (Fig. 1) can be considered as a suggestion of the existence of a disordered structure (Rocha & Klinowski, 1990a; Frias et al., 2013). According to the results of other researchers the reactivity of MK is greater when the population of 6-coordinated Al is minimal and the 4- and 5-coordinated Al populations are at a maximum (Edwards 2009; Frias et al., 2013). In agreement with these data is also the 29Si NMR spectrum of MK where a broad band representative of a range of environments including some with at least an Al atom in the second coodrination with Q4 type Si bonds is visible (Fig. 2; Frias ...
The aim here is the fabrication and characterization of nanostructured thin films of different materials inside microchannels to assist the integration process of electronic tongue in lab-on-a-chip devices. The ultrathin films were deposited inside the microchannels using dynamic layer-by-layer technique through copper (II) tetrasulphonated phthalocyanine (CuTsPc) and poly(allylamine hydrochloride) (PAH) bilayers, and also bilayers of poly(3,4-ethylenedioxythiophene) poly(syterenesulfonate) (PEDOT:PSS) and PAH. It was verified the best parameters involved in the nanostructuration of the materials throughout flow and time variations of the deposition of the electrolytes inside the microchannel. Moreover, the growth of the LbL films inside the microchannel was followed by UV-vis and impedance spectroscopy measurements. Through electrical impedance spectroscopy technique was observable that deposition of thin films PAH/CuTsPc was successful using a time of 8 min with a flow of 1500 μL/h, while ...
Blood analysis provides vital information for health conditions. For instance, typical infection response is correlated to an elevated White Blood Cell (WBC) count, while low Red Blood Cell (RBC) count, hemoglobin and hematocrit are caused by anemia or internal bleeding. We are developing two essential modules, deionization (DI) chip and microfluidic cytometer with impedance spectroscopy flow, for enabling the realization of a single platform miniaturized blood analyzer. In the proposed analyzer, blood cells are preliminarily sorted by Dielectrophoretic (DEP) means into sub-groups, differentiated and counted by impedance spectroscopy in a flow cytometer. DEP techniques have been demonstrated to stretch DNA, align Carbon Nanotubes (CNT) and trap cells successfully. However, DEP manipulation does not function in biological media with high conductivity. The DI module is designed to account for this challenge. H Filter will serve as an ion extraction platform in a microchamber. Sample and buffer do ...
For practical deployment of supercapacitors characterized by high energy density, power density and long cycle life, they must be realized using low cost and environmentally benign materials. Titanium dioxide (TiO2) is largely abundant in the earths crust; however, they show inferior supercapacitive electrochemical properties in most electrolytes for practical deployment. In this paper, we show that nickel doped TiO2 (Ni:TiO2) nanowires developed by electrospinning showed five times larger capacitance (∼200 F g−1) than the undoped analogue (∼40 F g−1). Electrochemical measurements show that the Ni:TiO2 nanowires have 100% coulombic efficiency. The electrodes showed no appreciable capacitance degradation for over 5000 cycles. The superior charge storage capability of the Ni:TiO2 could be due to its high electrical conductivity that resulted in five orders of magnitude higher ion diffusion as determined by cyclic voltammetry and electrochemical impedance spectroscopy measurements. ...
Dielectric spectroscopy (DS) of living biological cells is based on the analysis of the complex dielectric permittivity of cells suspended in a physiological medium. It provides knowledge on the polarization-relaxation response of cells to external electric field as function of the excitation frequency. This response is strongly affected by both structural and molecular properties of cells and therefore, can reveal rare insights on cell physiology and behaviour. This study demonstrates the mapping potential of DS after cytoplasmatic and membranal markers for cell-based screening analysis. The effect of membrane permittivity and cytoplasm conductivity was examined using tagged MBA and MDCK cell lines respectively. Comparing the permittivity spectra of tagged and native cell lines reveals clear differences between the analyzed suspensions. In addition, differences on the matching dielectric properties of cells were obtained. Those findings support the high distinction resolution and sensitivity of DS
A neural sensor is provided which receives raw input data defining a pattern, such as image or sound data, and generates a classification identifier for the pattern. The neural sensor has a pattern array former which organizes the raw input data into the proper array format. A first order processing section receives the pattern array and generates a first order feature vector illustrative of first order features of the input data. A second order processing section also receives the pattern array and generates at least one second order feature vector illustrative of gradients in the input data. A vector fusion section receives the feature vectors from the first and second order processing sections and generates a single fused feature vector which is provided to a pattern classifier network. The pattern classifier network, in turn, generates a pattern classification for the input data.
Dino Klotz. Electrochemical Impedance Spectroscopy (EIS) is a powerful tool to characterize electrochemical systems by probing the dynamics of the relevant charge carriers. In the field of photoelectrochemistry, photoelectrochemical impedance spectroscopy (PEIS: EIS conducted while illuminating the sample statically) is becoming a method of strong interest. Intensity modulated photocurrent /photovoltage spectroscopy (IMPS/IMVS) are relatively new and powerful techniques but only few results have been published using them.. The tutorial will provide a general introduction into EIS and the basic concept of impedance analysis will be explained, thereby demonstrating the capacity of this analysis method. This includes measurement, data analysis, modeling and interpretation. Further, the distribution of relaxation times (DRT) will be introduced as a valuable tool for the empirical analysis of impedance data.. The main focus of this segment will be dedicated to the trio of PEIS, IMPS and IMVS. ...
Cholesterol, Electrochemical Impedance Spectroscopy, Impedance, Impedance Spectroscopy, Membranes, Spectroscopy, Water, Concentrations, Donor, Fluorescence, Fluorescence Microscopy, Foundation, Lipids, Methods, Microscopy, Neutron, Phosphatidylcholine, Work, Amino Acid Substitutions, Concentration
Electrical impedance spectroscopy is a non-destructive method for analysing the structure and properties on different materials and objects.
TY - JOUR. T1 - A physical interpretation of impedance at conducting polymer/electrolyte junctions. AU - Stavrinidou, Eleni. AU - Sessolo, Michele. AU - Winther Jensen, Bjorn. AU - Sanaur, Sébastien. AU - Malliaras, George G.. PY - 2014/1. Y1 - 2014/1. N2 - We monitor the process of dedoping in a planar junction between an electrolyte and a conducting polymer using electrochemical impedance spectroscopy performed during moving front measurements. The impedance spectra are consistent with an equivalent circuit of a time varying resistor in parallel with a capacitor. We show that the resistor corresponds to ion transport in the dedoped region of the film, and can be quantitatively described using ion density and drift mobility obtained from the moving front measurements. The capacitor, on the other hand, does not depend on time and is associated with charge separation at the moving front. This work offers a physical description of the impedance of conducting polymer/electrolyte interfaces based ...
A new resonance-frequency based electronic impedance spectroscopy (REIS) system with multi-probes, including one central probe and six external probes that are designed to contact the breast skin in a circular form with a radius of 60 millimeters to the central ("nipple") probe, has been assembled and installed in our breast imaging facility. We are conducting a prospective clinical study to test the performance of this REIS system in identifying younger women (, 50 years old) at higher risk for having or developing breast cancer. In this preliminary analysis, we selected a subset of 100 examinations. Among these, 50 examinations were recommended for a biopsy due to detection of a highly suspicious breast lesion and 50 were determined negative during mammography screening. REIS output signal sweeps that we used to compute an initial feature included both amplitude and phase information representing differences between corresponding (matched) EIS signal values acquired from the left and right ...
Electrochemical impedance spectroscopy (EIS) is applied to detect pathogenic E. coli O157:H7 bacteria via a label free immunoassay-based detection method. Polyclonal anti-E.coli antibodies (PAb) are immobilized onto gold electrodes following two different strategies, via chemical bond formation between antibody amino groups and a carboxylic acid containing self-assembled molecular monolayer (SAM) and alternatively by linking a biotinylated anti-E. coli to Neutravidin on a mixed-SAM. Impedance spectra for sensors of both designs for increasing concentrations of E. coli are recorded in phosphate buffered saline (PBS). The Nyquist plots can be modeled with a Randle equivalent circuit, identifying the charge transfer resistance RCT as the relevant concentration dependent parameter. Sensors fabricated from both designs are able to detect very low concentration of E. coli with limits of detection as low as 10-100 cfu/ml. The influence of the different immobilization protocols on the sensor performance ...
Healthcare and diagnostics are moving towards molecular medicine. Hence, a lot of research is being performed on biosensors. However, rarely one has reached the commercialization phase because of the expensive infrastructure required for signal read-out. Electronic read-out methods, such as Electrochemical Impedance Spectroscopy (EIS), are preferred since they allow real-time and label-free signal generation and cheap implementation, because of the well-understood silicon (Si) microprocessing techniques. However, it is known that the covalent bond between Si and biomolecules is fairly weak, causing the gradual loss of bioreceptors from the surface, and hence a drift in signal and decrease in sensitivity and reliability1. Diamond is an attractive alternative, because of its semiconductive nature by doping, its chemical inertness, and its ability to be biofunctionalized. Furthermore, diamond, being a carbon (C) lattice, can form stable C-C bonds with biomolecules, enabling reuse of the surface without
Aptamers, which are in vitro-selected functional oligonucleotides, have been employed to design novel aptasensor due to their inherent high selectivity and affinity compared to traditional biorecognition elements. This report presents a novel aptamer biosensor for determining the endocrine disrupting compound (EDC), 17~-estradiol (E2), which was constructed from a SELEX-synthesized 76-mer biotinylated aptamer for 17~-estradiol incorporated in a dendritic generation 1 poly(propylene imine)- poly thiophene (G 1PPT-co-PEDOT) star copolymer-functionalised Au electrode via biotin-avidin interaction. The sensor platform and aptasensor were interrogated with scanning electron microscopy (SEM), FTIR, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV). The kinetic parameters of the sensor platform were determined by modelling the [Fe(CN)6r3/ - 4 (redox probe) Nyquist and Bode impedimetric spectra to the appropriate equivalent electrical circuit. The ...
Sunlight is vital for several biochemical processes of the skin organ. However, acute or chronic exposure to ultraviolet radiation (UVR) has several harmful effects on the skin structure and function, especially in the case of the failing function of antioxidative enzymes, which may lead to substantial tissue damage due to the increased presence of reactive oxygen species (ROS). The aim of this work was to investigate the combined effect of ultraviolet B (UVB) irradiation and oxidative stress on the skin barrier integrity. For this, we employed electrical impedance spectroscopy (EIS) to characterize changes of the electrical properties of excised pig skin membranes after various exposure conditions of UVB irradiation, oxidative stress, and the inhibition of antioxidative enzymatic processes. The oxidative stress was regulated by adding hydrogen peroxide (H2O2) as a source of ROS, while sodium azide (NaN3) was used as an inhibitor of the antioxidative enzyme catalase, which is naturally present
Electrochemical sensing methods have the great potential to achieve simple, sensitive, selective, and cost-effec-tive detection of biomolecules to diagnose and monitor various diseases. In this regard, we have developed DNA and protein diagnostic system based on electrochemical analytical method. In chapter 2, we developed a novel alkaline phosphatase (ALP) determination system based on the $Cu^{2+}$-mediated oxidation which could be detected by impedimetric detection method. It causes change of the interfacial properties of the electrodes and increased interfacial electron-transfer resistance is detected by electrochemical impedance spectroscopy (EIS). In chapter 3, we have developed a novel strategy to achieve label-free multiplex DNA detection system based on the projected capacitive touchscreen. The hybridization event significantly enhanced the capacitance on the electrode, which can be very conveniently detected by the projected capacitive touchscreen. In chapter 4, we developed an ...
Physiology Journal is a peer-reviewed, Open Access journal that publishes original research articles, review articles, and clinical studies in all areas of physiology.
Supplementary Materialssensors-20-01322-s001. and the worthiness increased Rabbit Polyclonal to IFI44 to 2.1 k, which was ascribed to the poor chemical conductivity [30]. Due to the reduced graphene oxide, the value of the rGO/DSPE was about 310 . This small semicircle appeared within the rGO/DSPE, which shows that the dynamic performance of the electronic transmission was poor. For the LC-rGO/DSPE, the value increased to 700 , which made the electroanalytical probe unable to reach the electrode surface to participate in the reaction. The results were in agreement with the conclusion from the CV. Open in a separate window Number 3 Electrochemical impedance spectroscopy of the DSPE, LC/DSPE, rGO/DSPE and LC-rGO/DSPE in 5 mmol/L [Fe(CN)6]3-/4? and 0.1 mol/L KCl with frequencies from 1 to 105 Hz. The hydrogen development has a serious effect on the electrochemical response. Hence, this property in the electrode surface was analyzed. As demonstrated in Number 4, the backdrop current from the ...
The Postdoctoral Appointee will have research experiences in lithium-ion battery or other electrochemical energy storage systems and efficiency in electrochemical analysis including cyclic voltammetry, electrochemical floating test, electrochemical impedance spectroscopy and lithium-ion battery testing. Be familiar with in-situ characterization techniques including FT-IR, XAS, or TEM to understand the interfacial reactivity at electrode surface and identify the chemical composition of the SEI. Design and conduct organic synthesis and polymer synthesis experiments to develop new organic compounds as new electrolyte solvents and additives with desired physical and electrochemical properties. Skills in organic/polymer synthesis, purification and chemical analysis by NMR, FTIR, Raman, GC-MS, SEM/EDS et al.. Track of record of scientific achievements in published papers, patents, manuscript submission, and presentation at academic conferences ...
Optical roughness of a pyrolytic graphite electrode with basal (PGEb) and edge orientation (PGEe), a glassy carbon electrode (GCE), and the same electrodes modified with mercury (MFE) was studied by an optical diffractive element (DOE) based sensor. Electrochemical characterisation of these electrodes used was performed by cyclic voltammetry (CV) and capacitance measurements (C-E curves and electrochemical impedance spectroscopy, EIS). The kinetics of phase transients of adenosine adsorbed on PGEb, and GCE modified with mercury layer of different thicknesses (thickness was changed from 0.02 to 2 mum) was studied by chronoamperometry (j-t curves) and capacitance measurements (C-E curves). In acidic (pH 5) solution adenosine forms two different two-dimensional (2D) physisorbed condensed layers on the MFE. The first of these (region 1) is located at more positive potential; the centre of this adlayer is situated around -0.4 V. The second 2D physisorbed film (region 111) is formed at more negative ...
Three porous carbons CSC-6, CSC-7, and CSC-8 were prepared by the carbonization of zinc chloride-pretreated chestnut shells at 600, 700, and 800°C under N2 atmosphere and had specific surface areas of 1754, 1987, and 1824m2g-1, respectively. The microstructure and surface functional groups of samples CSCs were characterized by thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and Raman spectroscopy. Electrochemical performances of CSCs-based supercapacitors were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge, self-discharge, cycle stability, and electrochemical impedance spectroscopy (EIS) in two-electrode cells. Comparative studies showed that the CSC-7-based supercapacitor exhibited the best electrochemical performance among all the CSCs-based supercapacitors. At a current density of 0.1Ag-1, the CSCs-based electrodes had the specific capacitances of 42.5, 105.4, and 83.4Fg-1 in 6M KOH solutions for CSC-6, ...
A protein-based electrochemical sensor for hydrogen peroxide (H2O2) was developed by an easy and effective film fabrication method where spinach ferredoxin (Fdx) containing [2Fe-2S] metal center was cross linked with 11-mercaptoundecanoic acid (MUA) on a gold (Au) surface. The surface morphology of Fdx molecules on Au electrodes was investigated by atomic force microscopy (AFM). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to study the electrochemical behavior of adsorbed Fdx on Au. The interfacial properties of the modified electrode were evaluated in the presence of Fe(CN)6 3−/4− redox couple as a probe. From CV, a pair of well-defined and quasi-reversible redox peaks of Fdx was obtained in 10 mM, pH 7.0 Tris-HCl buffer solution at −170 and −120 mV respectively. One electron reduction of the [2Fe-2S]2+ cluster occurs at one of the iron atoms to give the reduced [2Fe-2S]+. The formal reduction potential of Fdx ca. −150 mV (vs. Ag/AgCl ...
Electrophoretic deposition (EPD) method was used to fabricate gas diffusion electrodes (GDEs) for high temperature polymer electrolyte membrane fuel cells (HT PEMFC). Parameters related to the catalyst suspension and the EPD process were studied. Optimum suspension conditions are obtained when the catalyst particles are coated with Nafion® ionomer and the pH is adjusted to an alkaline range of about 8 e10. These suspensions yield good stability with sufficient conductivity to form highly porous catalyst layers on top of the gas diffusion layers (GDLs). GDEs were fabricated by applying various electric field strengths of which 100 V cm-1 yields the best membrane electrode assembly (MEA) performance. Compared to an MEA fabricated by the traditional hand sprayed (HS) method, the EPD MEA shows superior performance with a peak power increase of about 73% at similar platinum (Pt) loadings. Electrochemical Impedance Spectroscopy (EIS) analysis shows lower charge transfer resistance for the MEA ...
A-site cation-ordered PrBaCo2O5+d (PrBC) double perovskite oxide was synthesized and evaluated as the cathode of an intermediate-temperature solid-oxide fuel cell (IT-SOFC) on a samarium-doped ceria (SDC) electrolyte. The phase reaction between PrBC and SDC was weak even at 1100 °C. The oxygen reduction mechanism was investigated by electrochemical impedance spectroscopy characterization. Over the intermediate-temperature range of 450-700 °C, the electrode polarization resistance was mainly contributed from oxygen-ion transfer through the electrode-electrolyte interface and electron charge transfer over the electrode surface. An area-specific resistance as low as ~0.4 O cm2 was measured at 600 °C in air, based on symmetric cell test. A thin-film SDC electrolyte fuel cell with PrBC cathode was fabricated which delivered attractive peak power densities of 620 and 165 mW cm-2 at 600 and 450 °C, respectively. © 2008 Elsevier B.V. All rights reserved.. ...
EP. Randviir, O. Kanou, CM. Liauw, GJ. Miller, HG. Andrews, et al. GC. Smith. (2019). The physicochemical investigation of hydrothermally reduced textile waste and application within carbon-based electrodes. RSC Advances. 9, pp.11239-11252. E. Bernalte, J. Kamieniak, EP. Randviir, CE. Banks (2019). The preparation of hydroxyapatite from unrefined calcite residues and its application for lead removal from aqueous solutions. RSC Advances. 9(7), pp.4054-4062. EP. Randviir (2018). A cross examination of electron transfer rate constants for carbon screen-printed electrodes using Electrochemical Impedance Spectroscopy and cyclic voltammetry. Electrochimica Acta. 286, pp.179-186. SJ. Rowley-Neale, EP. Randviir, AS. Abo Dena, CE. Banks (2018). An overview of recent applications of reduced graphene oxide as a basis of electroanalytical sensing platforms. Applied Materials Today. 10, pp.218-226. E. Randviir (2017). Novel Research Methods Supporting Advanced Waste Treatment Technologies within a Circular ...
The plasticized polymer electrolytes based on polyvinylidene fluoride-co-hexafluoropropylene (P(VdF-co-HFP)), tetra (ethylene glycol) dimethyl ether (TEGDME), and lithium perchlorate (|TEX|$LiClO_4$|/TEX|) are prepared for the lithium sulfur batteries by solution casting with a doctor-blade. The polymer electrolyte with EO : Li ratio of 16 : 1 shows the maximum ionic conductivity, |TEX|$6.5\;{\times}\;10^{-4}\;S/cm$|/TEX| at room temperature. To understand the effect of the salt concentration on the electrochemical performance, the polymer electrolytes are characterized using electrochemical impedance spectroscopy (EIS), infrared spectroscopy (IR), viscometer, and differential scanning calorimeter (DSC). The optimum concentration and mobility of the charge carriers could lead to enhance the utilization of sulfur active materials and the cyclability of the Li/S unit cell.
Three techniques, i.e., pyrolysis of sucrose, spray of acetylene black, and propane vapor deposition, are adopted to coat carbon onto the surface of LiCoPO 4 particles, and their effects are compared. The LiCoPO 4/C composites are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS). The results show that the coating techniques determine the property of carbon films formed on the surface of LiCoPO 4 particles, which further affect the performance of LiCoPO 4. A complete and homogeneous carbon layer is the key to a high electrochemical activity and stable cycle performance. Among these LiCoPO 4/C composites, the material processed via the deposition technique shows a more uniform carbon layer than that of the others, thus it exhibits a large reversible capacity of 130 mA h g -1 with favorable cyclability and rate capability in the voltage range of ...
Impedance spectroscopy has been widely used to extract the electron-hole recombination rate constant in organic photovoltaic cells (OPVs). This technique is typically performed on OPVs held at open-circuit. Under these conditions, the analysis is simplified with recombination as the only pathway for the decay of excess charge carriers; transit provides no net change in the charge density. In this work, we generalize the application and interpretation of impedance spectroscopy for bulk heterojunction OPVs at any operating voltage. This, in conjunction with reverse bias external quantum efficiency measurements, permits the extraction of both recombination and transit rate constants. Using this approach, the transit and recombination rate constants are determined for OPVs with a variety of electron donor-acceptor pairings and compositions. It is found that neither rate constant individually is sufficient to characterize the efficiency of charge collection in an OPV. It is demonstrated that a large ...
Dielectric properties of a novel liquid crystal with direct transition from isotropic to twist grain boundary (TGB) phase were studied. Measurements were performed over a wide range of temperature in the isotropic phase, TGB(A), TGB(C) and SmC* phases. The Arrhenius plot of the relaxation frequency of the molecular process around the short axis shows a variation in the activation energy in the isotropic phase. This is attributed to smectic-like fluctuations in the isotropic phase. The dielectric relaxation strength in the TGBC phase has anomalous behaviour in the vicinity of TGB(C)-SmC* transition. The single cellective process observed in the TGB(C) phase splits into two processes in the SmC* phase. ...
A transdermal transport device includes a reservoir for holding a formulation of an active principle, a needle with a bore through which the formulation is transported between the reservoir and a target area of a biological body, and an impedance sensor. The impedance sensor has an electrode positioned to measure the impedance of a portion of the target area between the needle and the electrode to indicate the depth of penetration of the needle into the target area.
When polymer power cables were introduced into mediumvoltage applications in the late 1960s, the degradationphenomenon later referred to aswater treeingwas still unknown. However, this changedwithin a relatively short space of time. Just 5-10 years afterthese first polymer applications, faults began to appear thatcould be attributed to the new phenomenon-water treeing. Sincethen, cable manufacturers have been improving their designsgradually, and cables produced today are assumed to have muchlower susceptibility to water trees. However, water treeing isstill assumed to be the most important degradation process inthese applications.. There are huge amounts of polymer cable installations thatare degraded by water trees. Since many of these cables areinstalled in the same grid nets, one cable fault oftengenerates another. If two or more cables fail at the same time,the consequences can be extensive. A non-destructive diagnosticmethod makes it possible to assess cables and take action priorto ...
BioMEMS as microsystems designed for biomedical and biological applications provide various functions from micro implants, Lab-on-chip, PoC diagnostics to biosensors. This paper focuses on the sensing capability of BioMEMS in cell characterization, drug screening and biofilm detection. In situ staining and electrical approaches as impedance spectroscopy, dielectric spectroscopy and contactless impedimetric sensing are presented and discussed for applications in 3D cell culturing, for drug screening, sedimentation analysis in aquatic research and biofilm detection in indwelling devices.. Download. ...
The analysis of receptor activity, especially in its native cellular environment, has always been of great interest to evaluate its intrinsic but also downstream biological activity. An important...
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El Archivo Digital UPM alberga en formato digital la documentacion academica y cientifica (tesis, pfc, articulos, etc..) generada en la Universidad Politecnica de Madrid.Los documentos del Archivo Digital UPM son recuperables desde buscadores: Google, Google Academics, Yahoo, Scirus, etc y desde recolectores OAI: E-ciencia, DRRD, Recolecta (REBIUN-FECYT), Driver, Oaister, etc.
Biological toxins are an important part of our world, a reality with which we need to cope, so in parallel with understanding their mechanisms of action and thereby improving our fundamental knowledge, there are successful efforts to utilize them as therapeutics against some debilitating human and
A blue light shines through a transparent, implantable medical sensor onto a brain. The invention may help neural researchers better view brain activity.
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Malaria is a leading parasitic disease endangering the lives of half of the worlds population. Microfluidics paves way to indispensable portable sensors to enable early sensing hence defends lives. In this paper, we demonstrate a portable sensor based on dielectric spectroscopy capable of pre-treatment and malaria parasite detection. The complete sensor system consists of a microfluidic chip connected to portable impedance circuit board, which measures the dielectric value of blood cells to detect the infection. ...
The hydration of ions is related to physiologically, medically, and chemically relevant processes such as protein folding/precipitation, enzyme/ion channel/ion pump activity, action potentials generation, transport across membranes, self-assembly, interfacial charging, and aerosol formation (1-6). Ions interact with dipolar water molecules through ion-dipole interactions. The electrostatic potential around an ion decays with 1/R (with R being the distance away from the ion) and is damped by the high dielectric constant of water and the presence of other ions. The orientationally averaged interaction energy of a dipole and an ion is of a much shorter range, and decays with 1/R4. The structure and dynamics of water around ions have been studied with neutron scattering (7-9), x-ray diffraction (10, 11), x-ray absorption spectroscopy (12, 13), Raman spectroscopy (14), dielectric spectroscopy (15, 16), solvent relaxation measurements (17), vibrational dynamics measurements (18-22), infrared ...