Micro and Nanosystems - Volume 13, Issue 4, 2021

Background: Iron tailing causes great environmental and social problems. They contaminate water, air and soil. Therefore, it is of important significance to prepare iron tailing ceramsites with microscale pores which can recycle the deposited iron tailing. Objective: The aim of the research is to obtain iron tailing ceramsites with microscale pores and good mechanical performance. Methods: The iron tailing ceramsites have been characterized via Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Influence of the content of iron tailing, temperature and duration time on the mechanical performance of the obtained ceramsites was performed and the optimal sintering parameter was determined. The bulk density, apparent density and cylinder compressive strength of the obtained ceramsites increased as the iron tailing content, temperature and sintering time improved. Results: Duration time and sintering temperature play important roles in the formation and size of the pores of the ceramsites. The optimal iron tailing content and sintering parameter are 70 wt.%, 1100 °C for 40 min. The iron tailing ceramsites mainly consist of orthorhombic CaAl2Si2O8, monoclinic CaSiO3, hexagonal Ca7Si2P2O16, triclinic MgSiO3, triclinic Al2SiO5, and triclinic Ca2Fe2O5 phases. Iron tailing ceramsites from 1100 °C for 40 min are composed of irregular particles with several hundreds of micrometers improving the density and strength of the ceramsites. Conclusion: Iron tailing ceramsites containing microscale pores were prepared using iron tailing and fly ash, and exhibited excellent potential for application in the field of construction.

Background: Current comparators are useful in many analog circuits and communication systems. With the increasing demand to integrate wearable health monitoring systems in telemedicine and biomedical applications that help in early detection of abnormal conditions in patients, comparator is one of its cores. Objective: Wearable and implantable medical devices work primarily on the signal acquisition and wireless transmission. In the signal acquisition, Analog to Digital Converter (ADC) is the prime module. Conversion is done using the sampling process and samples are generated by comparing the input signal with the threshold level. For this purpose, comparator circuits are more preferable. This manuscript presents a novel dual output comparator design by using carbon nanotube field effect transistor second generation current controlled conveyor (CNCCCII). This CNCCCII is realized with the present- day technology called Carbon Nanotube Field Effect Transistors (CNFETs). Methods: The proposed comparator topology is designed with 32 nm CNFET technology files with a supply voltage of ±0.9 V using the Cadence Virtuoso simulator tool. The performance of the proposed design is tested using transient analysis, Montecarlo analysis, temperature sweep, and finally compared with the existing models. Results: The proposed comparator has the advantage of requiring a single CNCCCII with only one resistor and is preferable for monolithic IC fabrication. Conclusion: The proposed circuit implemented using CNFETs gives a substantial improvement in supply voltage requirement and less variation in output voltage levels over the existing technologies.

Background: Experimental data on the conditions for the formation of gravel materials containing hollow aluminosilicate microspheres with a possibility to receive optimum structure and properties depending on humidity with the use of various binders are presented in this article. This article focuses on the scientific study of the possibility to optimize the physical and mechanical properties of composite materials. Objective: The main goal of this research is an exploration of energy-efficient building materials to be used to replace natural materials with industrial wastes and development of the theory and practice of how to obtain light and ultra-light gravel materials based on mineral binders and waste dump ash and slag mixtures of hydraulic removal. The objective of this research is to study the composite material containing hollow aluminosilicate microspheres. Methods: The study is based on the application of the separation method for power and heat engineering functions. The method is based on the use of the structure optimality factor that takes the primary and secondary stress fields of the structural gravel material into account. It shows the possibility to obtain gravel material with the most uniform distribution of nano - and microparticles in the gravel material and to form stable matrices with minimization of stress concentrations. Experiments show that the thickness of the cement shell that performs power functions is directly related to the size of the raw granules. At the same time, the cement crust thickness regardless of the binder type has a higher formation rate for larger diameter granules when the moisture content increases. Results: The conditions of formation for gravel composite materials containing hollow aluminosilicate microspheres were studied. The optimal structure and properties of the gravel composite material were obtained. The dependence of the strength function on humidity and the binder type was investigated. The optimal size and shape of gravel material containing aluminosilicate hollow microspheres with a minimum thickness of a cement shell and a maximum strength function were obtained. Conclusion: The obtained structure enables us to separate power and heat engineering functions in the material and to minimize the content of the aggressive environment centers.

Background: The formation and modification of the surface of polypropylene fibers provide a versatile material for a variety of applications. Objective: This research examines the production of new materials by pneumatic spraying of a polypropylene melt jet, on the surface of which metal and metal oxide nanoparticles are prepared using the sol-gel technique and photoreduction followed by ultra-high frequency processing. We used the obtained materials to remove Bisphenol A in the photoreactor. Methods: Based on an analysis of the obtained values of the numerical characteristics in the spray zone and the physical essence of the criteria under consideration, a mechanism for the destruction of the melt jet from the formation of a fiber-forming system is proposed. Analysis of the degradation of Bisphenol A was carried out by electron spectroscopy and fluorescence. Results: A composite active layer, “polymer – inorganic nanoparticles”, on the surface of polypropylene fibers has been demonstrated to create new photocatalytic materials. Bisphenol A in water was examined as a toxicant. Conclusion: Based on the analysis of the obtained values of the numerical characteristics in the spray zone and the physical essence of the considered criteria, it was found that the pressure drop in the nozzle, the nozzle critical section area, and the rheological properties of the melt are dominating factors in the influence on the morphology and size of the ultra-fine fibers obtained by pneumatic spraying. It was determined that materials based on a polypropylene carrier with the largest diameter of 6.71 μm have the best sorption capacity for Bisphenol A. A decrease in the concentration of bisphenol A in water by more than two times in 30 minutes of UV irradiation in the presence of polypropylene was achieved without additional injection of oxidants.

Background: Scaling of the dimensions of semiconductor device plays a very important role in the advancement of Very Large-Scale Integration (VLSI) technology. There are many advantages of scaling in VLSI technology such as increment in the speed of the device and less area requirement of the device. Aggressive device scaling causes some limitations in the form of short channel effects which produce large leakage current. Large leakage current harms the characteristics of the device and affects the reliability of the device. Objective: The most important and popular reliability issue in Deep Sub Micron (DSM) regime is Negative- Bias Temperature Instability (NBTI). NBTI effect increases the threshold voltage of p-channel Metal Oxide Semiconductor (PMOS) device over the time and affects the different characteristics of the device. As a result, circuit delay exceeds the design specification and there may be timing violations or logic failure. Different performance parameters are observed under NBTI effect for different logic gates. Methods: This paper presents an impact of NBTI at 22nm Berkeley short-channel IGFET model4 (BSIM4) Predictive Technology Model (PTM) for Complementary Metal Oxide Semiconductor (CMOS) logic gates. Reliability simulations are utilized to evaluate the amount of gradual damage in PMOS device due to NBTI effect. Results: The impact of NBTI degradation is checked for various CMOS logic gates using Mentor Graphics’s Eldo circuit simulator. Output voltage and drain current are reducing over the time under NBTI effect. Conclusion: NBTI degradation increases the threshold voltage of PMOS device over time and affects the different characteristics of the device.

Background: Energy is a major concern in every aspect of our life. Solar energy is a renewable environmentally friendly source of energy. Therefore, solar cells are vastly studied with different technology and different material. Objective: The main objective here is to analyze InGaN material for solar cell applications with less complicated structures of MQW solar cells on revising solar cell with the recombination structure, I-V characteristics, and its efficiency. Methods: The device is simulated using SILVACO ATLAS, where the well and the barrier layers are inserted in the depletion region employing material combination of InGaN / GaN, which increases the solar cell performance parameter. This work focuses on the photogeneration rate, recombination in the active region as well as its current-voltage relation from the simulation. Results: With the increase in the number of QW periods in the active region of the device, the photovoltaic parameters especially conversion efficiency, increases significantly. Under space AM0 solar illumination, the cell efficiency increases up to 8.2 % for 20 MQWs with 20% Indium content for the InGaN/GaN structure. It enhances the External Quantum Efficiency (EQE) upto 36% at nearly 380nm wavelength range near the UV region. Conclusion: The modelled structure is efficiently simulated using TCAD SILVACO ATLAS, and the material Indium Gallium Nitride semiconductor shows an excellent solar cell performance with high solar radiation. It is also observed that with an increase in the number of well periods the solar cell performance increases, which demonstrates the feasibility of Indium Gallium Nitride solar cell with an additional MQW period as a power source.

Background: An analysis of equivalent circuits used to interpret the impedance of bioelectrode for electrocardiography shows that the best description is achieved using a double-time constant model of the skin-electrode interface. However, for the measurements, it is necessary to use equipment with high input impedance, which leads to the loss of information about the real change in the bio-potential. Objective: The aim of the study is to comprehensively investigate and select the equivalent model that is used to interpret the impedance of a composite bioelectrode with distributed parameters. Methods: We used theoretical and experimental research methods. Results: It is proposed for measuring bio-potential to use Ag/AgI/Al2O3 electrodes with distributed parameters. Such electrodes are characterized by a higher contact area and their impedance is described in terms of equivalent circuits with Constant Phase Elements (CPE). It was shown that the electrode impedance is well described over a wide frequency range by an equivalent circuit typical for distributed electrodes including two CPE elements. Conclusion: It is experimentally shown that the distributed Ag/AgI/Al2O3 electrode has at least 6 times smaller polarization contribution than a commercial Ag/AgCl cardiographic electrode. It may enable more accurate measurements of bio-potentials providing less pulse shape distortion caused by polarization of electrochemical biosensors.

Fill factor in the negative permittivity materials are tailored within the physically permissible limits to characterize the Brillouin zone for two-dimensional crystal under the propagation of both s and p-polarized waves. Two lowermost band-gaps are computed along with corresponding mid-band frequencies, where the plane wave expansion method is invoked for computational purposes. The rectangular geometrical shape is considered for the simulation, and all the results are calculated inside the ‘Γ’ point and ‘X’ point of the first Brillouin zone. Simulated findings depict monotonous variations of both band-gap width as well as mid-band frequency for higher negative permittivity materials, when the magnitude of fill factor is comparatively low, for both TE (Transverse Electric) and TM (Transverse Magnetic) mode of propagations. Lower negative permittivity leads to random fluctuations, which makes it unsuitable for photonic component design. Multiple forbidden regions may be observed for some specific artificial materials which can be utilized in the antenna or multi-channel filter design in higher THz region. Aims: The present paper aims to compute the shape of the first Brillouin zone from the fill factor for a two-dimensional photonic crystal structure. Background: EBG (Electromagnetic Bandgap) of a photonic crystal plays a major role in determining its candidature for optical applications, which is critically controlled by the fill factor. Therefore, it is significant to investigate the effect of F.F on the wave propagation characteristics of 2D PhC(Twodimensional photonic crystal). Objective: Investigation of metamaterial-based photonic crystal structure for electromagnetic band-gap analysis in the desired spectrum of interest as a function of fill factor inside the first Brillouin zone. Methods: Maxwell’s equations are solved using the plane wave propagation method to solve the problem, and simulation is carried out in MATLAB® software. Results: Both the first and second photonic band-gaps are simultaneously computed with a variation of refractive index differences of the constituent materials as well as with the fill factors. Results are extremely significant about the formation of narrowband and wideband filters on certain material combinations and structural designs. Conclusion: Better tenability is observed for metamaterial structure compared to conventional positive index materials, and fill factor has a great role in shaping the Brillouin zone and corresponding bandgap width.

Background: The porous SHS–TiNi alloy is a widely used material for repairing defects in bone tissues. Objective: The objective of the study is to comprehensively investigate porous SHS–TiNi alloy samples for fatigue strength under cyclic bending, to study deformation characteristics under quasistatic tension and bending, and to carry out the fractographic analysis of fracture features. Methods: The study employed the electrospark method for cutting plates from a porous isotropic SHS– TiNi rod 30 mm in diameter and 300 mm in length. Results: Deformation behaviour under tension and three-point bending of porous plates showed that porous samples undergo viscoelastic deformation due to the austenite–martensite (A→M) phase transformation. The fracture surfaces of elastic porous samples were studied by SEM. Microscopic studies of fracture surfaces revealed zones of quasi-brittle fracture of martensite and viscous fracture of austenite. The porous framework of intermetallic alloy exhibits a continuous brittle layer and numerous brittle non-metallic inclusions. However, successful fatigue tests showed that brittle phases and inclusions do not significantly affect deformation and fatigue characteristics of porous titanium nickelide. It was found that 70% of porous samples sustain 10⁶ cycles of deformation without fracture due to reversible A→M→A phase transformations in the TiNi phase, which is one of the components of multiphase porous alloy. Conclusion: Viscoelastic behavior of the porous sample and its high fatigue strength under cyclic loading is due to reversible deformation of the TiNi phase. The corrosion-resistant layer of the porous framework allows an effective use of SHS–TiNi.

Objective: This paper presents the design and simulation of double bridge-type capacitive RF MEMS switch by using FEM Tool. Methods: It is mainly concentrated on a low pull-in voltage, capacitance, and RF analysis. The beam is considered as a gold metal having the length of 595 μm along with the 1μm thickness and the dielectric is taken as Silicon nitride (Si3N4) by using Ashby’s method. The non-uniform meandering technique and perforations are used to reduce the pull-in voltage, by changing different beam thickness, air gap and materials. Results: The pull-in voltage of the proposed RF MEMS switch is 1.2 V. The scattering parameters are simulated by using Ansoft HFSS software. The simulation results of S-parameters such as return loss, insertion losses are, -19.27 dB and -0.20dB. The switch having good isolation is -63.94 dB at 8 GHz. Conclusion: The overall switch is designed with different beam thickness, various gap, and different materials to identify the best performance of the switch for low-frequency applications i.e X-bands.

Background: Microcantilever devices are widely used in biomedical because of their high sensitivity, better performance, low fabrication cost, robustness, and improved reliability over other equipment. The dynamic response of the device in different mediums, i.e., air, water and gas, depends on the vibrational mode. Vibrational modes decide how effectively the cantilever is going to respond while operating in a particular medium. Methods: In this paper, a microcantilever having a length 60μm, width 6μm, and thickness 1.5μm has been designed for measuring the density and viscosity of blood plasma. A Finite Element Analysis (FEA) is adopted to obtain the eigenfrequencies of the microcantilever device for different beam lengths in the ‘vacuum’ medium. The model for fluid-structure interaction has been presented and analyzed. Since the properties of blood and glycerol are analogous to each other, thus different concentrations of glycerol have been taken to deduce the rheological properties of the fluid. Results: The analytical results are found in close agreement with the FEA results. A comparative analysis of transverse and lateral vibrational modes is put forward to understand the behavior of the device. In addition, after simulating the model, it is observed that the cantilever can measure viscosities from 0.86-3.02 centipoise. Conclusion: FEM analysis of microcantilevers vibrating in the vacuum has been presented. Resonant frequencies in the vacuum of laterally and transversally vibrating microcantilever are calculated through an eigenfrequency analysis using Comsol multiphysics software, thus avoiding simulation time. A high degree of accuracy of the results is obtained. It is proved experimentally the advantages of lateral vibrations over transverse vibrations. In addition, the Simulink model is proposed for measuring the rheological properties of blood. The design is capable of measuring the blood plasma viscosities range. Our study shows that FEM analysis is a suitable tool for designing and simulation of bioMEMS.

Aim: The aim of this study is the derivation and assessment of quantum scaling length of Cylindrical Surrounding Double-Gate (CSDG) MOSFET with respect to Silicon body thickness. Objectives: To derive the quantum natural length of CSDG MOSFET with respect of Silicon body Thickness, observe the behaviour of the CSDG MOSFET at the nanoscale regime and compare the behaviour of the CSDG MOSFET with Cylindrical Surrounding Gate (CSG) MOSFET. Methods: The authors employed the mathematical analysis. The quantum energy level is analysed using Schrodinger equation by assuming one-dimensional approach and a negligible potential well. Results: The analytical results obtained from classical and quantum natural length are compared with the numerical simulations. Also, the model was compared with CSG MOSFET. Results show that proposed analytical close-form expression that approximately matches the numerical simulation, and the proposed CSDG MOSFET will be better than CSG MOSFET at quantum level even though it has smaller quantum natural length than CSG MOSFET. Conclusion: In this research work, quantum scaling length model and quantum scaling factor have been proposed using the quantum confinement approach. The performance assessment of the CSDG MOSFETs provided an opportunity of determining the scaling limit of CSDG MOSFETs by evaluating the trade-off between the quantum natural length and the classical natural length of CSDG MOSFETs. Results obtained were compared with CSG MOSFETs to show that CSDG MOSFETs offer better device characteristics.