Technology and design in electronic equipment

State of the art and outlook for development of Hall effect sensors for electronic devices

Viktor Sergiichuk — 2024-12-27

The fast development of solid electronics is contingent on the fast development of sensor electronics, including Hall sensors for different applications. The objective of this paper is to review classical and modern approaches to designing Hall sensors from bulk structure to quantum dimensions. Practical applications, advantages and disadvantages of Hall sensors are presented. In order to establish a theoretical basis for the development of Hall sensors, the study presents an overview of the mathematical models for Hall effects in semiconductor materials. Based on the analysis of the presented mathematical models, the authors offer recommendations for selecting the optimal material for Hall sensors with the highest sensitivity. This paper concludes with the discussion of future prospects for the development of sensors based on the Hall effect.

Investigating the possibility of using CdTeSe-based materials for ionizing radiation detectors

Оleksandr Kondrik — 2024-12-27

The article describes the study of the properties of materials based on CdTe_1-xSe_x suitable for X-ray and gamma radiation detectors. The purpose of the study was to determine by computer modeling the optimal content of impurities and structural defects and the nature of their influence on the electrophysical and detector properties of CdTe(Mn, Mg, Zn)Se, based on the properties of CdTe_{0. 9}Se_{0. 1} and CdTe_{0. 05}Se_{0. 95} doped with indium. The values of concentrations N_i, activation energies E_i, and capture cross sections of non-equilibrium charge carriers σ_i for i-th defects were used as input data for modeling. The author studied the influence of defects on the change in resistivity ρ, concentration of free electrons n₀ and holes p₀, Fermi level F, life time of non-equilibrium charge carriers τ and charge collection efficiency η of ionizing radiation detectors based on CdTeSe:In at the temperature of 25°C. The paper also highlights the results of quantitative studies of the influence of the impurities and defects content on the properties of CdTe_{0. 95}Se_{0. 05} with the possible additives of Mn, Mg, and Zn. The regularities of change in ρ, F, η, depending on the content of indium impurities, cadmium and tellurium vacancies were established. The method of achieving a steady high-resistance state was considered. The direction of further research is formulated in order to establish the optimal composition of detector materials based on CdTe_1-xSe_x with additives of manganese, magnesium, and zinc.

Study of glow discharge parameters in a coaxial electrode system with a thin cathode

Olga Andriienko — 2024-12-27

Various gas discharges are the basis of many electronic, photonic devices and ion-plasma technologies. Among them, the glow discharge is the most common and is often mentioned in the scientific and technical literature. In this study, we model a glow discharge in a cylindrical coaxial system with dielectric electrode ends in the hydrodynamic drift-diffusion approximation. The model parameters are: anode diameter 10 mm, cathode diameter 30 µm, voltage 800 V, temperature of the working argon gas 300 K, pd ≈ 2 Pa∙m (p — working gas pressure, d — distance between electrodes), which corresponds to the right side of the minimum area of the Paschen curve for discharge ignition. The reactions of ionization of atoms by electron impact, generation and quenching of metastable atoms, elastic collision of electrons with atoms and elastic collision of ions, resonant recharge of ions, Penning ionization, and secondary ion-electron emission of the cathode are taken into account. The potential distribution and concentration of charged particles in the interelectrode space are calculated within the framework of a self-consistent problem, and the electron current density, concentration of charged particles, and potential along the cathode are presented. The effect of the ballast resistor R_b of the blocking capacity on the parameters and discharge mode is determined. The obtained results can be used in plasma technologies to modify the internal surfaces of metal, hollow, long parts with a small cross-sectional size.

Start-up characteristics of gravity heat pipes with a threaded evaporator

Roman Melnyk — 2024-12-27

The authors experimentally study start-up characteristics of copper gravitational heat pipes with a threaded evaporator filled with four different heat transfer fluids — methanol, R141b refrigerant, isobutane (refrigerant R600a), and n-pentane — that do not freeze at temperatures as low as –30°C. The heat pipes were 260 mm long, had a diameter of 12 mm, a thread length in the evaporation zone of 45 mm, a thread pitch of 0. 5 mm, and a fluid volume of 1.6 – 1.7 ml (filling ratio of 50 – 55%). It was shown that changing the inclination angle (15°, 60°, 90°) does not significantly affect the temperature in the heating zone of the heat pipe (maximum 5°C for methanol). More significant is the influence of the ambient air temperature (–30°C, +20°C and +40°C). The maximum thermal regime stabilization time (22 – 24 min) was observed in the heat pipe with methanol at an ambient temperature of –30°C, while the minimum stabilization time (11 – 12 min) was recorded for heat pipes with isobutane and n-pentane at an air temperature in the chamber of +40°C.

The influence of operating temperature conditions of led modules on their electro-optical and operational parameters

Demyd Pekur — 2024-12-27

Modern LEDs are characterised by high energy efficiency, which makes them one of the most promising light sources in many industries. The efficiency and durability of LED modules largely depend on the temperature conditions of operation. Elevated temperatures can adversely affect electro-optical parameters such as luminous flux and spectral characteristics, as well as accelerate degradation processes. This article investigates the effect of temperature conditions of LED modules on their electro-optical and operational parameters. The paper considers how temperature unevenness in the LED module affects their luminous flux and service life. It is determined that when assessing the efficiency and durability of LED modules, it is necessary to take into account the standard deviation of the LED temperature from the average. Given the presence of temperature gradient between LEDs in a LED module, the service life of the latter is estimated by the temperature of the most heated LED, as shown in this paper. The influence of the deviation of the LED temperature from the average on the overall luminous efficiency of LED modules based on them is demonstrated. In particular, with a standard temperature deviation of 20°C, the relative decrease in the module’s luminous flux can be about 1%. For the considered cases, an increase in temperature unevenness by 10°C reduces the lifetime of the LEDs more than three times. To ensure the efficient operation of LED modules, it is necessary to reduce the standard deviation of temperature from the mean value through effective heat dissipation and improved cooling system design. The use of LEDs with lower temperature coefficients can also reduce the sensitivity to temperature fluctuations, increasing the overall luminous flux and luminous efficiency of LED lighting devices based on them.

Influence of surface effect on the resistance of electrodes of electrosurgical instruments

Andrii Dubko — 2024-12-27

The paper presents a study of the influence of the surface effect on the environments involved in electrosurgical interventions. Taking into account the influence of the surface effect when designing new electrosurgical instruments allows reducing overheating and necrosis of living biological tissues, which is of practical interest and is a topical task. The authors plot frequency dependences of the depth of the surface layers of electrodes and biological tissues. For biological tissue, the depth of the surface layer is at a frequency of 440 kHz is considerable, about 1 m. For copper, at such a frequency, the depth of the surface layer is 0. 1 mm. Using the example of round and rectangular electrodes made of copper and stainless steel 410, in a wide frequency range (1 kHz – 1 MHz), the resistance values of these electrodes are calculated. The work shows that increasing the outer perimeter of the electrode reduces its resistance. Thus, increasing the total length of the outer perimeter of the electrode, allows you to increase its effective area conducting high-frequency current, which creates conditions for increasing the efficiency of electrosurgical instruments.

Determination of biological tissue parameters for simulation tasks in electrosurgery

Ievgenii Dziuba — 2024-12-27

The problem of creating innovative surgical equipment becomes an urgent necessity in wartime. A promising direction in surgery is the improvement of electrosurgical technology, which is successfully implemented for welding and cutting living biological tissues and is characterized by high speed and proven efficiency. The important aspect of designing electrosurgical equipment is experimental research and verification of the effectiveness of the proposed solutions in practice. However, experiments in this area are complicated by the need to have living tissues at hand, the properties of which are significantly different from the properties of dead biological tissues. So, an adequate mathematical model of living tissue can significantly simplify experimental and adjustment work with the electrical part of electrosurgical equipment in the laboratory. The aim of this work is to experimentally determine the impedance properties of living biological tissues and assess their dependence on the power and duration of the electrosurgical procedure at the operating frequencies of the equipment for further use of the obtained data in creating mathematical models. Using a specially created experimental device, the parameters of biological tissue were determined as the load of the electrocoagulator. By measuring the phase shift between the welding current and the voltage on the electrodes of the electrocoagulator, it was found out that its value does not exceed 1° at different levels of power and duration of exposure for the experimental device with the operating frequency of the electrosurgical equipment. As a result, it is proposed to consider the kind of the impedance of living biological tissues as purely active, since in the entire studied range it is determined mainly by its active component, while the reactive component is insignificant. This approach allows the use of lower-order equations for calculations, which essentially simplifies mathematical models.