Changes In Electrical Properties Research Articles

Effects of Polarity Inversion Layer on Performances of Lateral-Field-Excitation Piezoelectric Sensors Based on Lithium Niobate Single Crystal

In this work, lateral-field-excitation (LFE) piezoelectric sensors based on polarity inversion layer are designed and fabricated, then frequency stabilities and sensitivities on electric property changes of liquids are tested. Because the polarity inversion layer can suppress the spurious modes, the stabilities of the LFE devices with a polarity inversion layer are obviously better than that of LFE devices with no polarity inversion layer. On the changes of liquid conductivity and permittivity, the sensitivities of the LFE devices with a polarity inversion layer are 2.4 times and 2.1 times higher than that of LFE devices with no polarity inversion layer, respectively. The polarity inversion layer of the lithium niobate crystal plate can be realized conveniently by heat treatment, therefore, the technology of the polarity inversion layer can play an important role in improving the sensing performances of LFE sensors.

Electro-Thermal Characteristics of Hybrid TiO2-SiO2 Nanofluid Coolants in An Electrically-Active System

Thermal management in an electrically-active system is a challenging engineering branch due to the critical requirement for rapid cooling rates with inhibition of electrical discharge. A Polymer Electrolyte Membrane Fuel Cell (PEMFC) is an example of a system that needs both conditions to be critically fulfilled. The use of conventional deionized water with low electrical conductivity as the cooling fluid ensures insignificant electrical potential losses but large thermal capacities can only be achieved with a significant penalty to the PEMFC system size. Formulation of nanofluid coolants has been highly successful for systems working under normal environments, but research towards new nanofluid coolants for active electrical systems are relatively new. This paper reports a fundamental investigation on the electrical and thermal behaviors of a hybrid 1%v TiO2-SiO2 (at 50:50 ratio) nanofluid dispersed in 60:40 water/ethylene glycol solution. A test bench consisting of a heated rectangular channel combined with continuous electrical supply at 0.7 V and 3 A nominal current was developed to simulate the operating conditions of a PEMFC stack cooling. The test variables are the heater temperature and Reynolds number (300 to 700) of the coolants. The cooling profiles and changes in electrical properties of the system and coolants were analyzed. Significant increase in cooling rates were achieved by the hybrid nanofluids (200% to 250%) compared to water and water/ethylene glycol coolants. The electrical analysis indicates that the power drop is low for water and water/ethylene glycol but drops rapidly in an exponential profile (between 15% to 45%) which also leads to a visible increase in the electrical conductivity of the nanofluids coolants. As such, further research is needed to reduce the apparent electrical discharge problem before a suitable nanofluid coolant can be developed for electrically-active systems.

Designing efficient soil resistivity measurement technique for agricultural wireless sensor network

SummaryThis paper presents the study and method for measuring the electrical properties of the agricultural soil using a wireless sensor network to counter the dynamic changes in electrical properties of soils under variable rainfall and flood conditions. Soil moisture and nutrients can be correlated with the resistance of soil, which is the essential electrical property of the soil. Resistivity can help us to classify different agricultural soil types and can be used for real‐time monitoring of crop fields. The diverse resistivity soil patterns may help to classify the physical, chemical and biological properties of soil. In our research work, we have taken soil from different districts of Madhya Pradesh state and classified it based on resistivity. We have also designed a low‐cost resistivity sensor module with a mathematical justification of the results. The new sensor module has been tested on different soil samples of Madhya Pradesh, and wireless sensor network (WSN) has been proposed to collect and process the data for application in the agriculture fields. The paper also describes the challenges and the various methodologies for the measurement of soil resistivity and moisture using the Internet of Things (IoT) architecture.

Effect of particle size distribution on functional properties of Ce0.9Y0.1O2-d ceramics

This paper has investigated the dependence of the mechanical and electrical properties of ceramics Ce0.9Y0.1O2-d (CeY) on changes in the proportion of submicron size particles in a powder with bimodal particle size distribution. The powder was prepared by mixing the products of sol-gel (submicron size fraction with average size of 0.2 μm and specific surface area of 39.52 m2/g) and solid-state synthesis (micron size fraction with average size of 5.68 μm and specific surface area of 4.81 m2/g) in a certain ratio to get different proportion of the fractions. All ceramics samples were formed by isostatic pressing with further annealing under identical conditions. The microstructure of ceramic samples was studied using scanning electron microscopy and static volumetric analysis. The impedance spectroscopy method has determined the temperature dependencies of the grain boundary resistance fraction, which are strongly related to the particle size distribution. The microhardness of samples was determined by the Vickers method. A nonlinear change of mechanical and electrical properties was found for the samples having approximately 20% content of submicron size particles. The dependence of the total electrical conductivity and the dependence of the microhardness on the particle size distribution possess the maxima and minima points for these compositions, respectively. The particle size distribution of powders has a strong impact on the ceramics formation process and allows to control the microstructure and physical properties of materials. We have proposed the ceramics model of “arched structure”, formed by bimodal compositions sintering, which allows to predict the properties of ceramics with other compositions.

Phase formation and structural evolution of multicomponent (CrFeCo)1-yNy films

The Cantor alloy (CoCrFeMnNi) and its variants, in bulk as well as thin films, have been extensively studied. They are known to exhibit cubic crystal structures and thermodynamic stability regardless of their complex chemical composition. Therefore, they may find use as hard, wear-resistant, corrosion and oxidation-resistant coatings. The addition of light elements, such as nitrogen, is known to help improve these properties further through processes such as amorphization and nitride compound formation. Here, we investigate the ternary CrFeCo system to study the effects of nitrogen addition. (CrFeCo) 1-y N y multicomponent thin films are grown on silicon substrates by DC magnetron sputtering. Changes in crystal structure, morphology, mechanical and electrical properties with gradual increases of nitrogen in the film are described and discussed. Increased addition of nitrogen from 14 at.% to 28 at.% in the film leads to a transformation from an fcc to a bcc crystal structure, affects both the mechanical and electrical properties. XPS analysis shows the tendency of nitrogen to bond with Cr over other metals. The films display hardness values between 7 and 11 GPa with resistivities values ranging between 28 and 165 μΩ cm. • Multicomponent (CrFeCo)Ny coatings deposited by reactive magnetron sputtering • Effect of nitrogen content on structure, morphology and composition was studied. • Phase formation and evolution with changes in nitrogen content • Mechanical and electrical properties of (CrFeCo)Ny thin films

Preparation of chip type negative temperature coefficient thermistor

A thermistor is a class of resistor whose resistance varies with temperature. The two types of thermistors are Negative temperature coefficient (NTC) thermistor and Positive temperature coefficient (PTC) thermistor. NTC thermistors have a negative electrical resistance versus temperature (R/T) relationship. These thermistors are extremely versatile and accurate. This makes them best for a wide variety of applications that measure temperature. They find application in firebrand photographic processing, meteorological, geological, and oceanographic research equipment, as well as in consumer and household appliances. This paper presents the development of a chip-type Mn-Ni based negative temperature coefficient thermistor with varying CuO (Dopant) concentration. The changes in electrical properties are also reported. The expected results indicate an increase in resistivity, material constant and temperature coefficient of resistance (a) with an increase in CuO concentration for all the compositions.

Electrical properties of 3 MeV proton irradiated silicon Schottky diodes

This work presents the effects of proton irradiations on the electrical properties of n-silicon-based Schottky diodes. A change in electrical properties of the diodes due to 3 MeV proton irradiation to the fluence of 1017 ion cm−2 was investigated by current-voltage (I-V) and capacitance-voltage (C-V) techniques. A drastic decrease in forward current by a factor of 103 indicates a reduction of free injected effective carrier density in the space charge region. This reduction in the density is observed by a decrease in rectification ratio after proton irradiation. The results in general indicate that proton induced defects are responsible for the recombination/compensation of charge carriers resulting in an increase in the resistivity of the material. An increase in the resistivity is confirmed by high series resistance and low doping density evaluated on the irradiated diode. A change in dominated diode conduction mechanism due to irradiation presented here is of technological importance. Furthermore, the results presented here would, certainly, contribute to an ongoing study on the induced damage by radiation in silicon.

Preparation of Polycrystalline‐Mixed Graphene Film with Benzene Solution by Electromagnetic Induction for Application in Metal Corrosion Protection

AbstractMetals used in the electronics, machinery manufacturing, and construction industry are often chemically reactive and corrosion‐prone, while barriers on a metal as a conventional method for anticorrosion always have negative effects including a toxic nature, thickness increase over time, and changes of electrical and optical properties after surface coating. This study employs a benzene solution to induce a rapid formation of a polycrystalline graphene film on copper foils or iron sheet substrates under atmospheric conditions by electromagnetic induction, which is non‐toxic and environment‐friendly and produces favorable anticorrosive effects. The microscopic analysis shows that the as‐grown film is a polycrystalline graphene complex of graphene crystallites. It is revealed that the copper foils or iron sheets with the graphene film is significantly resistant to strong corrosion, with the corrosion current density is one order of magnitude lower when compared with samples without the graphene films. The polycrystalline structure of the graphene film can prevent the electronic conduction of the surface, thereby reducing corrosion and local over‐corrosion phenomena when metals are situated in a long‐term exposure to corrosive environments.

Disparate structural changes in the titanium dioxide thin film coated on the p-type Si and porous silicon textures after gamma irradiation

Gamma irradiation effects on the thin film of titanium dioxide (TiO2) coated on p-type silicon (Si) and porous silicon (PSi) by sol–gel spin coating technique is investigated for the gamma dose of 100 to 1000 mGy. Characterization studies by the X-Ray Diffraction, Fourier Transform Infrared and Photoluminescence spectroscopy, and I-V study revealed the measurable changes in structural, optical and electrical properties due to gamma irradiation which are disparate in the hetero-junction on silicon and porous silicon texture. The anatase phase of TiO2 experienced linear defects then the rutile phase structure. Band gap energy is decreased while the dielectric constant is increased with increase of gamma dose. The strain due to crystallization of sol–gel of TiO2 on Si substrate is higher than the PSi substrate and found to be changed after irradiation. Porous texture is found to be suitable for formation of larger crystallite with less strain which can provide mechanical stability.

Tunable n-Type Conductivity and Transport Properties of Cubic Boron Nitride via Carbon Doping

The recent discovery of direct conversion of hexagonal boron nitride (h-BN) into quenched BN (Q-BN) and single-crystal cubic BN (c-BN) by pulsed laser annealing (PLA) have been implemented to fabricate carbon-doped c-BN with dopant concentration ranging from 2 × 1019 to 7 × 1021 cm–3. Micro Raman analysis shows a total conversion of h-BN into phase-pure c-BN, whereas the X-ray diffraction (XRD) confirms the presence of the cubic structure with (111) epitaxy on c-sapphire. Hall measurements demonstrate the n-type electrical property, and the temperature-dependent resistivity measurements confirm the semiconductor-like profile of the doped c-BN. Consistent changes in resistivity, Hall mobility, and other electrical properties were investigated with the variance in dopant concentration level. We have observed a shift in the conduction mechanism with temperature from the resistivity vs temperature analyses. At the high-temperature regime (130–330 K), the activation energy lies in between 0.012 and 0.074 eV, whereas at the low-temperature regime (20–130 K), the activation energy was obtained to be in between 0.0024 and 0.0083 eV. The lower values of activation energies, showing a complete ionization of the impurity atoms even at room temperature, are surmised to result from dopant-profile broadening. The enhanced electrical activation and superior quality c-BN films open exciting avenues for next-generation device applications.

Early Hypoexcitability in a Subgroup of Spinal Motoneurons in Superoxide Dismutase 1 Transgenic Mice, a Model of Amyotrophic Lateral Sclerosis

In amyotrophic lateral sclerosis (ALS), large motoneurons degenerate first, causing muscle weakness. Transgenic mouse models with a mutation in the gene encoding the enzyme superoxide dismutase 1 (SOD1) revealed that motoneurons innervating the fast-fatigable muscular fibres disconnect very early. The cause of this peripheric disconnection has not yet been established. Early pathological signs were described in motoneurons during the postnatal period of SOD1 transgenic mice. Here, we investigated whether the early changes of electrical and morphological properties previously reported in the SOD1G85R strain also occur in the SOD1G93A-low expressor line with particular attention to the different subsets of motoneurons defined by their discharge firing pattern (transient, sustained, or delayed-onset firing). Intracellular staining and recording were performed in lumbar motoneurons from entire brainstem-spinal cord preparations of SOD1G93A-low transgenic mice and their WT littermates during the second postnatal week. Our results show that SOD1G93A-low motoneurons exhibit a dendritic overbranching similar to that described previously in the SOD1G85R strain at the same age. Further we found an hypoexcitability in the delayed-onset firing SOD1G93A-low motoneurons (lower gain and higher voltage threshold). We conclude that dendritic overbranching and early hypoexcitability are common features of both low expressor SOD1 mutants (G85R and G93A-low). In the high-expressor SOD1G93A line, we found hyperexcitability in the sustained firing motoneurons at the same period, suggesting a delay in compensatory mechanisms. Overall, our results suggest that the hypoexcitability indicate an early dysfunction of the delayed-onset motoneurons and could account as early pathological signs of the disease.

Electron Density-Change in Semiconductor by Ion-Adsorption at Solid-Liquid Interface.

The change in electrical properties of electrodes by adsorption or desorption at interfaces is a well-known phenomenon required for signal production in electrically transduced sensing technologies. Furthermore, in terms of electrolyte-insulator-semiconductor (EIS) structure, several studies of energy conversion techniques focused on ion-adsorption at the solid-liquid interface have suggested that the electric signal is generated by ionovoltaic phenomena. However, finding substantial clues for the ion-adsorption phenomena in the EIS structure is still a difficult task because direct evidence for carrier accumulation in semiconductors by Coulomb interactions is insufficient. Here, a sophisticated Hall measurement system is demonstrated to quantitatively analyze accumulated electron density-change inside the semiconductor depending on the ion-adsorption at the solid-liquid interface. Also, an enhanced EIS-structured device is designed in an aqueous-soaked system that works with the ionovoltaic principle to monitor the ion-dynamics in liquid electrolyte media, interestingly confirming ion-concentration dependence and ion-specificity by generated peak voltages. This newly introduced peculiar method contributes to an in-depth understanding of the ionovoltaic phenomena in terms of carrier actions in the semiconductors and ionic behaviors in the aqueous-bulk phases, providing informative analysis about interfacial adsorptions that can expand the scope of ion-sensing platforms.

Effect of Zn-doping on the structural, optical and electrical properties of thermally vacuum evaporated CdTe thin films

Cadmium telluride (CdTe) thin film was fabricated on a glass substrate using thermal vacuum evaporation and zinc (Zn) was doped with varying atomic ratios using stacked layer method. The structural, optical and electrical properties of the fabricated films were thoroughly investigated as a function of doping concentration. XRD patterns revealed all Zn-doped CdTe thin films as polycrystalline materials with cubic structures. All the films had relatively intense (111) diffraction peaks but the intensity of the peaks reduces with the increase of doping concentration. The optical properties, such as transmittance, absorption coefficient, bandgap, penetration depth, Urbach energy and dielectric constants were evaluated by UV-Vis-NIR spectrophotometry. When doping concentration is increased from 0 at. % to 20 at. % average optical transmittance and Urbach energy increase from 87% to 94% and 127 meV to 409 meV, respectively, while the optical bandgap goes down from 1.51 eV to 1.43 eV. On the other hand, higher doping concentration shifts the absorption edge toward a longer wavelength and increases the penetration depth significantly. Electrical characterization determined by Hall measurements using the van der Pauw method shows that 20 at. % Zn doping in pure CdTe film increases the carrier concentration from 1.95 × 1014 cm−3 to 27.52 × 1014 cm−3 and activation energy from 1.623 eV to 2.603 eV but decreases the carrier mobility from 19.34 cm2/VS to 6.23 cm2/VS. Changes in electrical transport properties caused by doping are described in terms of charge carrier scattering.

Application of Ohmic-Vacuum Combination Heating for the Processing of Senior-Friendly Food (Multiphase Food): Experimental Studies and Numerical Simulation.

The popularity of senior-friendly food has been increasing as the world enters the age of an aging society. It is required that senior-friendly food products are processed with the new concept of processing techniques that do not destroy the nutritional and sensory values. Ohmic heating can be an alternative to conventional heating methods for processing senior-friendly food with retaining excellent taste and quality because of less destruction of nutrients in the food. In this study, the ohmic–vacuum combination heating system was developed to process a multiphase type of senior-friendly food. Changes in physical and electrical properties of senior-friendly model foods were investigated depending on the experimental conditions such as vacuum pressure intensity and vacuum pretreatment time. Numerical simulations based on the experimental conditions were performed using COMSOL multiphysics. The ohmic–vacuum combination heating method with agitation reduced the heating time of the model food, and non-uniform temperature distribution in model food was successfully resolved due to the effect of vacuum and agitation. Furthermore, the difference was found in the hardness of solid particles depending on the vacuum treatment time and intensity after the heating treatment. The ohmic–vacuum combination heating system appeared effective when applying for the senior-friendly foods in multiphase form. The simulation results matched reasonably well with the experimental data, and the data predicted through simulation could save the cost and time of experimentation.

Gamma-Induced Image Degradation Analysis of Robot Vision Sensor for Autonomous Inspection of Nuclear Sites

There is an increasing desire to conduct autonomous inspection of nuclear sites using robots. However, the presence of gamma radiation in nuclear sites induces degradation in vision sensors. In this paper, the effects of gamma radiation on a robot vision sensor (CMOS camera) used for radiological inspection is examined. The analyses have been carried out for two types of images at different dose rates: a) dark images b) illuminated images. In this work, dark images and chessboard images under illumination are analysed using various evaluation metrics to evaluate the effect of gamma radiation on CMOS Integrated Circuit (IC) and electronic circuitry of the sensor. Experimental results manifest significant changes in electrical properties like the generation of radiation-induced photo signal in sensing circuitry and radiation-induced noise affecting the visual odometry of the robot. System-level degradation for gamma dose rates upto 3 Gy/min intensifies, making data from the imaging sensor unreliable for the visual odometry. However, images captured for gamma dose rate upto 3 Gy/min can be used for surveillance purpose.

Age-related reductions in the excitability of phasic dorsal root ganglion neurons innervating the urinary bladder in female rats

Previous studies have revealed an impairment in bladder sensory transduction in aged animals. To examine the contributions of electrical property changes of bladder primary afferents to this impairment, we compared the electrical properties of dorsal root ganglion (DRG) neurons innervating the bladder among young (3 months), middle-aged (12 months), and old (24 months) female rats. The DRG neurons were labeled using axonal tracing techniques. Whole-cell current-clamp recordings of small and medium-sized neurons were performed to assess their passive and active properties. Two patterns of firing were identified based on responses to super-threshold stimuli (1.5, 2.0, 2.5, and 3.0 × rheobase): tonic neurons fired more action potentials (APs), whereas phasic neurons fired only one AP at the onset of stimulus. Tonic neurons were smaller and had a slower rate of AP rise, longer AP duration, more depolarized voltage threshold, and greater rheobase than phasic neurons. In phasic neurons, there was an age-associated increase in voltage threshold and an increase of rheobase (P < 0.05), suggesting an age-related decrease in excitability. In addition, both middle-aged and old rats had longer AP durations and slower rates of AP rise than young rats (P < 0.05). In tonic neurons, old rats had a greater AP overshoot and greater rate of AP rise, but no age-associated changes were identified in any other electrical properties. Our results suggest that the electrical properties of tonic and phasic bladder afferents are differentially altered with aging. A decrease in excitability may contribute to age-related reductions in bladder sensory function.

Changes in electrical properties and void distribution of mung bean sprouts during hot water heating

Changes in electrical properties and void distribution of mung bean sprouts during hot water heating

Study and Classification of Cell Bio-Impedance Signature for Identification of Malignancy Using Artificial Neural Network

This article presents development of a microcapacitive sensor-based bio-impedance classification system for identification of malignant cells in a known volume (400 $\mu \text{L}$ ) of biological tissue sample. Malignancy induces various physical changes in an affected cell, among which increased intracellular water and sodium ion content are a couple of prominent ones. In this work, the change in electrical properties of a cell [here white blood cell (WBC)] that is membrane and cytoplasm permittivity due to afore-mentioned reasons is used for distinguishing malignant from normal cells based on their deviation in bio-impedance signature. This change in bio-impedance signature of the WBC is measured by exciting the mentioned microcapacitive sensor by a 2 V p-p signal. The developed system consists of an on-board impedance analyzer to carry out bio-impedance spectroscopy over a frequency range of 1–100 kHz. The bio-impedance data are then obtained from the sensor for different concentrations of cultured human malignant and normal white blood cells. The difference in impedance values between concentrations is then used as a discerning factor for identification the degree of malignancy, for which an artificial neural network (ANN) is employed. A detailed study considering detection efficiency for this ANN revealed classification accuracy up to 95.0%, upon which this ANN model is transferred to a portable single board computer (SBC) along with other associated circuitry that could carry out the same classification at a nominal power consumption of 516.45 mW.

Surface modification and properties modulation of rGO film by short duration H2 and NH3 plasma treatment

Reduced graphene oxide (rGO) is a versatile material due to the presence of oxygen functionalization. One of the methods to tune the properties of rGO for the specific application is plasma treatment. Plasma H 2 and NH 3 are known introduced surface defects for increasing surface reactivity and inducing substitutional doping on rGO film. They need to be further discussed with the changes in electrical and optical properties of the film for the construction of devices such as electrical, optical, and electro-optical sensors. This article reports the effect of H 2 and NH 3 plasma treatment on the surface and properties of rGO film using a variety in plasma power and temperature. We found low-power H 2 plasma at low- and medium-temperature induced further de-oxygenation of rGO. A tiny etching effect by H 2 plasma slightly reduces the conductivity, σ to 54.01 S/cm from the reference rGO value of 448.90 S/cm. Low-power H 2 plasma at high-temperature left the high defective sites due to plasma etching. The σ was reduced to 8.04 S/cm. Medium-temperature medium-power NH 3 plasma did not effective for N-doping. An etching effect by NH 3 plasma noticeably reduces the σ to 5.79 S/cm. Medium-temperature high-power and high-temperature medium-power NH 3 plasma induce N-doping but at the same time significantly etch the rGO. They significantly reduce the hole concentration and lower the σ to 0.48 S/cm. High-power high-temperature NH 3 plasma rigorously induces N-doping but extreme plasma etching results in poor surface condition and film discontinuity. The film exhibited electron as a majority carrier but with the lowest σ of 0.05 S/cm.

Synthesis of vanadium dioxide thin films and nanostructures

Vanadium oxides (VxOy) are classic “smart functional materials” used in a wide array of thermochromic, electronic, and catalytic applications. Specifically, vanadium dioxide (VO2) class nanomaterials are of enormous interest due to their unique first order reversible metal-insulator phase transition (MIT) behavior accompanied by a structural phase transition, inducing dramatic changes in electrical and optical properties with large lattice deformation. To date, a plethora of reports exemplifying the MIT characteristics of VO2, synthetic methods of VO2, and modulating VO2 phase transition temperatures (Tc) have been published. In this Tutorial Review, we present an overview on the fundamentals of the VO2 band structure and principles of MIT and outline various reported synthetic approaches for VO2 thin films, including dimensionally oriented VO2 nanostructures. Discussion on recent trends in VO2 applications, challenges in VO2 synthesis, and future perspectives are also elaborated in detail.