Contact Devices Research Articles

Change of Electrical and Transport Properties of Nickel Oxide by Carrier Concentration and Temperature through First-Principle Calculations

Nickel is typically used as one of the main components in electrical contact devices or connectors. Nickel oxide (NiO) is usually formed on the surfaces of electrodes and can negatively impact system performance by introducing electrical contact resistance. The thermal, electrical, and transport properties of NiO, as a Mott insulator or a p-type semiconductor, can be altered by operating and environmental conditions such as temperature and stress/strain by contact. In this study, we investigate the fundamental material properties of NiO through the first-principle calculations. First, we obtain and compare the lattice parameter, magnetic moment, and electronic structure for NiO via the WIEN2K simulations with four different potentials (i.e., GGA, GGA + U, LSDA, and LSDA + U). Then, using the WIEN2K simulation results with LSDA + U potential that produces a highly accurate bandgap for NiO, we calculate the electrical conductivity and electrical part of the thermal conductivity of nickel and NiO as a function of temperature and carrier concentration through the BoltzTraP simulations. Systematic simulation results revealed that the electrical conductivity relative to the relaxation time for NiO increases with the carrier concentration, while it shows a slightly decreasing trend with temperature under a fixed carrier concentration. By contrast, the electrical part of the thermal conductivity shows an increasing trend considering carrier concentration and temperature.

Enhanced Performance of CdTe Solar Cells with Sb2Se3 Back Contacts

The barrier at CdTe/metal interface severely limits the efficiency of CdTe photovoltaic devices. Herein, the effectiveness of a thermally evaporated Sb2Se3 buffer layer as a back contact in CdTe solar cells is investigated, revealing a significant enhancement in device performance. Through optimization of Sb2Se3 thickness, a remarkable increase in the open‐circuit voltage (VOC) to 804 mV is achieved, leading to a substantial efficiency improvement of 12.84% when compared to the Au‐only back contact device. X‐ray photoelectron spectroscopy (XPS) reveals a well‐matched energy band alignment at CdTe/Sb2Se3 interface, confirming favorable conditions for hole transport. To further enhance the device performance, Cu doping is implemented in the Sb2Se3 film, resulting in additional improvements to the VOC and fill factor (FF) of the Cu‐doped configuration to 819 mV and 72.35%, respectively, while also enhancing the overall efficiency to 14.3%.

Sensor data analysis and development of machine learning models for detection of glaucoma

This paper focuses on analysis of data acquired using Triggerfish contact lens sensor and devices for continuous monitoring of cardiovascular system properties. One of the aims of our research is to build machine learning models that can be applied in clinical practice to detect glaucoma independently of currently used imaging techniques. We show that cardiac sensor data derived attributes are complementary to Triggerfish data and improve mean AUC estimates of the predictive models. We propose methods of attribute generation for raw data recorded by the devices. During data preprocessing we consider division of 24-hour monitoring period for time intervals depending on physiological circadian cycle properties. Comprehensive comparison of model predictive performance metrics is included. Our predictive model involving measurements of corneal biomechanical properties and sensor data based attributes provides AUC of 0.87. It can support glaucoma detection without direct intraocular pressure measurement. We also refer to the issues related to personalized medicine and application of machine learning techniques.

Optical Emission Spectroscopy of Cadmium Dominated Discharges Applied for Assessment of Explosion Protection

An assessment for the safe use of electrical equipment in explosive atmospheres can be performed with the aid of a spark test apparatus. Therefore, an anodic tungsten wire with 200 µm diameter is moved along the surface of a rotating cadmium disc (cathode). The explosion chamber enclosing the electrodes is filled with a highly explosive mixture of hydrogen and air. Depending on surface topology and relative movement of the contact pair, discharges occur randomly. A model contact device is used to investigate the plasma properties and the discharge characteristics near the thermo-chemical ignition threshold of the explosive atmosphere that typically occur at voltages around 30V and currents around 30mA.Spectroscopic investigations reveal that the emission of the discharges is dominated by atomic lines of cadmium, which allow the determination of distribution temperatures.

Surface Effect in Nano-Scale Fretting Contact Problems

Abstract The fretting contact behavior of nanostructured materials is significantly influenced by the surface effect. A model of fretting contact between a nano-sized rigid cylindrical indenter and an elastic half-plane is established based on Gurtin–Murdoch (G–M) surface elasticity theory, with which the surface effects on the stress and displacement distributions and the size of stick region (no-slip region) in the contact zone are systematically studied. It is found that the surface effect induces an additional traction besides the external force applied by punch, which could help to smoothen the stress and displacement distributions. The normal surface-induced traction related to the residual surface stress is opposite to the externally applied compression, which results in a material stiffening in the contact zone so that the contact radius, normal displacement, and normal stress decrease compared with their classical counterparts. The tangential surface-induced traction is also opposite to the externally applied frictional stress, consequently leading to reductions of the shear stress and tangential displacement induced by friction in the contact zone. More interestingly, the surface effect leads to three possible states in the contact zone, including complete slip, partial slip, and complete stick, instead of the solely partial slip state in classical fretting contact models without surface effect. Among them, the complete stick due to the action of surface residual stress is more beneficial for inhibiting the wear of contact devices, which can be realized by reducing the indenter size. The present research does not only help one to better understand the physical mechanism in nano-scale fretting contact problems, but should also guide the anti-wear design in nano-electro-mechanical (NEMs) systems.

Contactless and continuous blood pressure measurement according to caPTT obtained from millimeter wave radar

Continuous measurement of blood pressure (BP) is very important for assessing the health of the cardiovascular system. In this paper, a new system is first-time established to contactlessly and continuously measure BP according to the central-artery pulse transit time (caPTT) which is acquired from the neck and chest areas simultaneously with single millimeter wave (mmWave) radar. The two signals are separated by beam-component focusing and then BP is estimated by regression fitting. The correlation of the PTT’s variation measured by radar and contact device is verified by data from 16 subjects. The effectiveness of BP estimation is evaluated by data from 27 subjects. It is illustrated that the correlation of PTT’s variation is up to 0.91 and the errors of SBP and DBP are 5.54±7.62 mmHg and 4.68±6.15 mmHg respectively. The developed system in this work suggested that single radar has the potential to continuously measure BP in daily life.

Wall-to-Solids Heat Transfer in a Coil-Shaped Rotating Spiral Gas–Solid Contacting Device (2)

らせん軸周りの回転で粒子を輸送するコイル状らせん型装置について，既往の研究で用いた小型（JIS規格20Aサイズ）装置と比べて，体積で10.6倍の大きさであるJIS規格50Aサイズのステンレス製180°ロングエルボを組み合わせた5旋回コイル状らせんを製作し，粒子輸送速度と壁面–粒子間の伝熱速度を測定した．粒子には，既往の研究で用いた球形粒子に加え，新たに天然鉱物を破砕した非球形粒子を用いた．らせん内の粒子層の体積と，らせん内壁面のうち粒子と接触する面積を，粒子の安息角を用いたモデルで推定した．装置内粒子層体積は，モデルの予測とほぼ一致した．壁面と粒子の間の伝熱係数は，既往の小型装置で求めた伝熱係数の相関式とおおむね一致した．粒子群交換モデルによる伝熱係数の推算値と実測値間に差異があり，この原因として壁面付近の粒子密度が低い層の伝熱抵抗が影響していると示唆された．

РАЗРАБОТКА МЕТОДИКИ ГИДРОДИНАМИЧЕСКИХ ЭКСПЕРИМЕНТОВ С ДИСКОВЫМ РАСПЫЛИТЕЛЕМ

. A technique for hydrodynamic experiments has been developed to study a disk atomizer in a rotary mass transfer apparatus. In the course of experiments, the indicator method determines the average residence time of the liquid on the disk contact device, the volume of liquid retained on the disk contact device, the average diameter of the droplets formed, and the height of the gas-liquid layer

ИНДИКАТОРНЫЙ МЕТОД ИССЛЕДОВАНИЯ КОНТАКТНОГО УСТРОЙСТВА

It is proposed to use the indicator method for the experimental determination of the average residence time of the liquid on the new disk contact device. It is proposed to use an aqueous solution of MgCl2 as an indicator

Estimation of Effciciency of Contact Devices in a Diabatic Fractionating Column with Distributed Heat Removal

Estimation of Effciciency of Contact Devices in a Diabatic Fractionating Column with Distributed Heat Removal

Neutron irradiation of Hydrogenated Amorphous Silicon p-i-n diodes and charge selective contacts detectors

Hydrogenated amorphous silicon is a well-known detector material for its radiation resistance. For this reason it has been used in particle beam flux measurements and in solar panels designed for space applications. This study concern 10μm thickness, p-i-n and charge selective contacts planar diode detectors which were irradiated with neutrons to two fluence values: 1016neq/cm2 and 5 × 1016neq/cm2. In order to evaluate their radiation resistance, detector leakage current and response to x-ray photons have been measured. The effect of annealing for performance recovery at 100 °C for 12 and 24 h has also been studied. The results for the 1016neq/cm2 irradiation show a factor 2 increase in leakage current that is completely recovered after annealing for p-i-n devices while charge selective contacts devices show an overall decrease of the leakage current at the end of the annealing process compared to the measurement before the irradiation. X-ray dosimetric sensitivity degrades, for this fluence, at the end of irradiation, but partially recovers for charge selective contact devices and increases for p-i-n devices at the end of the annealing process. Concerning the 5 × 1016neq/cm2 irradiation test (for p-i-n structures only), due to the activation that occurred during the irradiation phase, the measurements were taken after 146 days of storage at around 0 °C, during this period, a self-annealing effect may have occurred. Therefore, the results after irradiation and storage show a noticeable degradation in leakage current and x-ray sensitivity with a small recovery after annealing.

Management of Thrombosed Dialysis Access Circuits.

Thrombotic occlusion of autologous arteriovenous fistulas or synthetic arteriovenous grafts is a serious adverse event in hemodialysis patients and declotting should be performed before next hemodialysis session, in order to avoid a central venous catheter. Various techniques exist to declot a thrombosed vascular access, including open surgical thrombectomy, catheter-directed thrombolysis and use of different types of percutaneous thrombo-aspiration catheters and mechanical thrombectomy devices. These devices can be categorized as devices with direct wall contact and hydrodynamic devices without direct wall contact. Technical and early clinical outcome results of percutaneous hemodialysis declotting are high and ranging between 70 and 100%; late clinical patency results are much lower related to restenosis or re-thrombosis; these patency results are higher for autologous arteriovenous fistulas compared to synthetic arteriovenous grafts and mainly depend on the combined efficacy of successful thrombectomy and durable treatment of the underlying stenoses, associated with the acute thrombosis.

Perovskite band engineering for high-performance X-ray detection

Perovskite-based X-ray detector, which is widely applied in fields of scientific research and medical diagnosis, has drawn much attention for its superior optoelectrical properties. To improve the detection performance, band engineering is becoming the hot topic for perovskite properties modulation. In this article, we review the recent progress of perovskite-based X-ray detectors with band engineering process from three aspects, which are background introduction, band theory of heterojunction devices, and optimized electrode contact devices. Lastly, research status and strategies are summarized and perspectives of future progress are analyzed. We hope this review can provide constructive instructions and suggestions for future development of band engineering for perovskite-based high-performance X-ray detector.

Optimization of the content of isobutane in the feed stream of the plant for sulfuric acid alkylation of isobutane with olefins

The raw materials for the industrial production of moto- and air-alkylates are isobutane and butane-butylene fractions containing in their composition a component, n-butane, which is inert for the reaction of sulfuric acid alkylation of isobutane with olefins. In accordance with the Specifications TU 0272-024-00151638-99, the content of n-butane in the isobutane fraction, depending on the grade of the fraction, is 0.7÷20% wt. Its presence reduces the useful reaction volume of the alkylation reactor, and when separating the components of the alkylation reaction mass, it is necessary to use a distillation column (debutanizer). The possibility of including an additional column in the technological scheme for removing n-butane from the composition of the fraction (respectively, isobutane concentration) before it is fed into the alkylation reactor is being considered. This is of particular importance for factions with a brand below "High Brand". The study is conducted using the Honeywell UniSim Design software system. The Peng-Robinson method was used to calculate the properties of process stream components. The theoretically optimal design of the apparatus was calculated: when using a distillation column with a pressure in the apparatus of about 400 kPa to reduce the content of n-propane in the distillate (obtained isobutane fraction) to 0.001 mol. the share will require 48 theoretical plates, the accepted reflux ratio R = 8.9, the temperatures in the condenser and reboiler are 26.88 and 47.27 °C, respectively. A computational experiment has shown that in order to achieve the practical absence of n-butane in the obtained isobutane fraction (concentration of about 0.1% wt.), it is possible to use a distillation column with the following technological modes: the number of plates is 60, the feed plate is 15, the efficiency of contact devices is 0.8; the pressure in the column is about 400 kPa, the temperature in the condenser and reboiler is Тk=28.91÷29.05 ℃ and Тр=46.72÷47.25 ℃, respectively, reflux ratio R=20.41. This fraction also does not contain pentanes.

Optimization of technological regimes of the deisopentanizer column for the preparation of the feed stream of the low-temperature isomerization unit PGI-DIG/280-NK

Raw fractions used in isomerization plants contain isopentane, which is the target product, and its presence in the feed as “ballast” occupies the useful volume of the reactor. To optimize the composition of processed raw materials, a number of enterprises have included a deisopentanizer column in the technological scheme. The paper evaluates the possibility of optimizing the technological regimes and design parameters of a deisopentanizer for a low-temperature isomerization unit that does not have a column in the technological scheme for extracting isopentane from the composition of the feedstock. The studies were carried out using the Honeywell UniSim Design modeling system. The properties of the fraction components were calculated using the Peng-Robinson method. Calculations were made for two types of raw materials containing 8.7÷19.7% wt. isopentane. The performed calculations established that in order to achieve almost complete recovery of isopentane in the feed stream from the hydrotreating section, the distillation column should contain 63 theoretical plates, and the minimum reflux ratio should be Rmin = 12.3. At the same time, the presence of normal pentane in the distillate of the column will not exceed 0.07% wt., and in the bottom product, the content of isopentane will also not exceed 0.07% wt. The operation of a distillation column is simulated, containing 80 plates (the efficiency of the contact device is 0.8), a feed plate is 33. The feedstock consumption is 62550 kg/h, the temperature is 40°C and the pressure is 294.2 kPa. The convergence of iterative processes by the Honeywell UniSim Design environment was obtained using active specifications: the content of isopentane in the cube is 0.0007wt. share and pentane in the distillate 0.0007wt. share. The obtained technological modes provide almost complete extraction of isopentane from the composition of the raw material, namely by 99.37÷99.7%, while for industrial conditions it is essential to implement the calculated temperature profile along the height of the column. The possibility of using a column with the same diameter in its exhaustive and strengthening parts is shown.

A Non-Contact Cow Estrus Monitoring Method Based on the Thermal Infrared Images of Cows

Traditional methods of cow estrus monitoring technology are not suitable for the current needs of large-scale, intensive and welfare-based farming. There is a need to improve the detection rate of cow estrus and to reduce the emergency response caused by wearing contact devices. Furthermore, it is necessary to verify the practical effectiveness of the LOGISITC and SV (support vector machine) models for modeling cow estrus. In this paper, we have proposed a non-contact cow estrus monitoring method based on the thermal infrared images of cows and have proposed a lab-color-space-based feature extraction method for the thermal infrared images of cow eyes and vulvas. The test subjects were 10 Holstein cows, monitored on a fixed basis, to determine the best segmentation contour. The LOGISTIC and SVM (support vector machine) models were used to establish the cow estrus model using the thermal infrared temperature variation in cows in estrus and cows not in estrus. The experimental results showed that the heat detection rate of the LOGISTIC-based model was 82.37% and the heat detection rate of the SVM-based model was 81.42% under the optimal segmentation profile. The highest temperature in the eye and vulva of cows was the input, and the recall rate was above 86%. The heat monitoring method based on thermal infrared images does not cause stress to cows and meets the needs of modern dairy farming for welfare breeding.

A Hybrid Schottky–Ohmic Drain Contact for Thermally Stressed Beta‐Gallium Oxide Field‐Effect Transistors

Degradation of ohmic contacts on β‐Ga2O3 under thermal stress conditions is a severe issue that hinders its high‐temperature applicability. Herein, a hybrid Schottky–ohmic drain contact (HSD) is demonstrated in β‐Ga2O3 field‐effect transistors (FETs). It is compared with a conventional ohmic drain contact (OD) after extended thermal annealing. Pulsed drain bias measurement is conducted to investigate the trapping process at the interface of both drain contacts with the β‐Ga2O3 channel. Even with the extended Schottky metal region, the β‐Ga2O3 FET with the HSD contact exhibits similar contact and on‐resistance. Additionally, it shows field‐effect mobility higher than that of the OD contact device. Enhanced off‐state breakdown characteristics are achieved.

State-of-the-Art in Smart Contact Lenses for Human–Machine Interaction

Contact lenses have traditionally been used for vision correction applications. Recent advances in microelectronics and nanofabrication on flexible substrates have now enabled sensors, circuits, and other essential components to be integrated on a small contact lens platform. This has opened up the possibility of using contact lenses for a range of human–machine interaction (HMI) applications, including vision assistance, eye tracking, displays, and healthcare. In this article, we systematically review the range of smart contact lens materials, device architectures, and components that facilitate this interaction for different applications. In fact, evidence from our systematic review demonstrates that these lenses can be used to display information, detect eye movements, restore vision, and detect certain biomarkers in tear fluid. Consequently, whereas previous state-of the-art reviews in contact lenses focused exclusively on biosensing, our systematic review covers a wider range of smart contact lens applications in HMI. Moreover, we present a new method of classifying the literature on smart contact lenses according to their six constituent building blocks, which are the sensing, energy management, driver electronics, communications, substrate, and the input/output interfacing modules. Based on recent developments in each of these categories, we speculate the challenges and opportunities of smart contact lenses for HMI. Moreover, based on our analysis of the state-of-the-art, we develop guidelines for the future design of a self-powered smart contact lens concept with integrated energy harvesters, sensors, and communications modules. Therefore, our review is a critical evaluation of current data and is presented with the aim of guiding researchers to new research directions in smart contact lenses.

Spin polarization in quantum point contact based on wurtzite topological quantum well.

Manipulating spin polarization in wide-gap wurtzite semiconductors is crucial for the development of high-temperature spintronics applications. A topological insulator revealed recently in wurtzite quantum wells (QWs) provides a platform to mediate spin-polarized transport through the polarization field-driven topological edges and large Rashba spin-orbit coupling (SOC). Here, we propose a spin-polarized device in a quantum point contact (QPC) structure based on ZnO/CdO wurtzite topological QWs. The results show that the QPC width can sufficiently control the lateral spin-orbit coupling (SOC) as well as the band gap of the edge states through the quantum size effect. As a result, the spin-polarized conductance exhibits oscillation due to the spin precession, which can be controlled by adjusting the voltage imposed on the split gate. The QPC-induced large spin splitting is highly nonlinear and becomes strong close to the gap. The spin splitting of the edge states will be suppressed for QPC widths greater than 50 nm, and thus lead to an extremely long spin precession length. This QPC width-dependent lateral SOC effect provides an emerging electrical approach to manipulate spin-polarized electron transport in topological wurtzite systems.

Skin Problems due to Treatment with Diabetes Technology: A Narrative Review

Diabetes devices, such as insulin pumps, glucose sensors, and integrated automated insulin delivery systems, have brought about a transformative impact on the management of diabetes. This impact has been particularly significant for individuals with type 1 diabetes and increasingly for those with type 2 diabetes. These devices are designed for continuous wear, necessitating the consistent use of infusion sets, patch pumps, or glucose sensors that are inserted into the skin. Regrettably, numerous studies have highlighted that skin-related issues stemming from diabetes devices are rather common. These problems encompass various forms of skin injury, allergic and irritative contact dermatitis, itching, wound formation, scarring, and lipodystrophies. The utilization of diabetes devices, both in the present and the foreseeable future, faces significant challenges due to these skin complications, but preventive strategies exist for especially skin injuries including use of a skin care regimen or patches. These challenges culminate not only in the discontinuation of device usage but also in decrease in quality of life and heavier disease burden. This narrative literature review comprehensively synthesizes existing knowledge about skin problems triggered by diabetes devices, encompassing children, adolescents, and adults. The review delves into definitions, underlying causes, prevention strategies, and treatment approaches. Finally, the review provides recommendations for future research directions in skin problems and suggestions for advancement of in the part of diabetes devices in close contact with the skin to reduce device-related skin problems.