Sandeep Arya

Structural, optical, magnetic and antibacterial study of pure and cobalt doped ZnO nanoparticles

In this research paper, pure and Co-doped ZnO nanoparticles were synthesized by using the wet precipitation method. The structural, morphological, optical and magnetic properties of the pure and Co doped ZnO nanoparticles were investigated. X-ray diffraction (XRD) spectra of Co doped ZnO NPs shows the shifting of characteristic XRD peak toward the higher angle which revealed that dopant Co is successfully incorporated into the lattice structure of ZnO nanoparticles. Structural morphology of pure and Co-doped ZnO nanoparticles samples was ascertained by using the scanning electron microscopy which confirms the formation of fine and clear spherical nanocrystallites with clear and distinctive boundaries. Energy-dispersive X-ray spectroscopy spectra show the elemental composition of Co2+ ions effectively in lattice site of Zn2+ ions. Photoluminescence and Raman spectra indicate the presence of oxygen vacancies and donor defects in the doped samples. UV–visible absorption spectroscopy showed the blue shifting of absorption edge as compared to pure ZnO nanoparticles sample. Pure and Co-doped ZnO nanoparticles revealed considerable changes in the M–H loop, particularly the diamagnetic behavior changed into ferromagnetic for Co-doped samples in vibrating sample magnetometer investigation. In this study, the antibacterial properties of the cobalt doped zinc oxide were further studied against three Gram-negative pathogens via using agar well diffusion technique. Co doped nanoparticles samples were then investigated as antibacterial agent to control the bacterial growth. It is further confirmed from our study that Co-doped ZnO NPs and their exposure to sunlight enhanced the antibacterial activity against three bacterial pathogens under study.

A Novel ZnO-Methylene Blue Nanocomposite Matrix for Biosensing Application

A novel hybrid matrix of zinc oxide-methylene blue (ZnO-MB) has been successfully developed for biosensing application. The introduction of methylene blue into the ZnO thin film leads to reduction in the charge transfer resistance and suggests an increase in the electron transfer capacity of the composite. Glucose oxidase (GOx) was chosen as the model enzyme and effectively immobilized on the surface of hybrid ZnO-MB nanocomposite matrix. Electrochemical measurements were employed to study biosensing response of the GOx/ZnO-MB/ITO bioelectrode as a function of glucose concentration. The low oxidation potential (−0.23 V) of the hybrid bioelectrode, in a mediatorless electrolyte, makes it resistant against interference from other bio-molecules. The low value of Michaelis-Menten constant (2.65 mM) indicates that immobilized GOx retains its enzymatic activity significantly on the surface of nanocomposite hybrid matrix that results in an enhanced affinity towards its substrate (glucose). The ZnO-MB nanocomposite hybrid matrix, exhibiting enhanced sensing response (0.2 μAmM−1cm−2) with long shelf-life (>10 weeks), has potential for the realization of an integrated biosensing device.

Finite element modelling of piezoelectric micro-cantilever as Gas sensor

This paper presents the modelling and design of piezoelectric based micro-cantilever for operation in enclosed environmental conditions. The successful design of cantilever is based on the interdependence of various mechanical and electrical parameters and further their dependence on the selected material and chosen geometry. Thus the end result depends on the mechanical and electrical sensitivities of the cantilever. The cantilever design is based on the material selection as well as determination of geometrical dimensions. In this proposed design, an aluminium material is selected for cantilever design on the silicon substrate. Systematic steps toward optimization of geometrical dimensions include initial analytical estimates of geometrical dimensions, followed by finite-element modelling and analysis of such cantilevers under the applied electric field. The observed design have shown variation in free end of micro-cantilever beam for different gases. Thus, this proposed cantilever can be a fine gas sensor.

Biological and electrical properties of biosynthesized silver nanoparticles

In this work, silver nanoparticles (AgNPs) were synthesized biochemically at room temperature using aqueous extract of rhizome of Rheum australe plant. The as-synthesized AgNPs were further studied for their morphological, biological and electrical characterization. The morphological studies, such as scanning electron microscopy, X-ray diffraction and UV–vis spectrum confirmed their successful synthesis. Biological analysis revealed their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Electrical characterization showed that the conductivity of the mixture of AgNPs with DPPH assay is more than the AgNPs dispersed in distilled water. The obtained results may have potential applications as sensors.

Performance analysis of ZnO and HfO2 micro-pillars based capacitive antennas

Abstract In this research paper, performance analysis of two different material-based micropillars capacitive antennas is proposed. The method involves formation of self-organized mask, micropillar formation by using process of etching and metal deposition (Au/Cr) on the top and bottom of micropillars. For fabrication of these capacitive antennas, we considered 2-inch p-type silicon (Si) wafers as a substrates material while upper and lower plates of capacitive antenna were fabricated by using gold as plating material on top and bottom. Both capacitive antennas were fabricated by taking the two different materials (ZnO and HfO2) micropillars which acts a dielectric material between two upper and lower gold plates. For realization of both antennas firstly we have simulated both the antenna using CST Microwave studio software and thereafter fabricated by using appropriate microfabrication technique. Both the metamaterial-based capacitive antennas were designed by taking dimension of 35 × 26 mm on the 2″ Si substrate. The thickness (h) and dielectric constant (εr) of silicon substrate were taken as 0.270 mm and 11.7, respectively. The proposed antenna was designed to operate at frequency range of 1–10 GHz, which signifies that return loss (S11) parameter must be less than −10 dB and voltage standing wave ratio must be less than 2. To validate the design, various parameters of RF antenna such as the return loss, gain, surface current distribution, and radiation patterns were obtained and compared for the fabricated antennas. The simulated and experimental results were found to show good agreement.

Analytic model of microcantilevers as low frequency generator

Finite element method (FEM) based simulation has been carried out, and an analytic model of microcantilevers using piezoelectric excitations is proposed. The model is based on the type of the selected material and geometry of the structure. The investigations are carried out with rectangular microcantilevers using silicon as the substrate. The high frequency analytic signals are applied to the input piezoelectric electrodes, and the resultant signal generated at the output piezoelectric electrode is recorded and analyzed. The analysis of the results showed that the proposed system is capable of generating a low frequency signal. Two microcantilevers with different dimensional aspects are used, and the results verified the application of microcantilever array as a low frequency signal generator.

Effect of Enhancement Technique on Nonuniform and Uniform Ultrasound Images

The absence of adequate scientific resources in the area of medical sciences sometimes leads to improper diagnosis of diseases and hence the treatments of such diseases are affected badly. However, with the advancement of technology, the complicacy of various malfunctions inside the human body reduces. Ultrasound imaging is one of the biomedical scanning techniques that let the pathologist make comment reasonably and accurately on the disease or irregularity seen in the scan while low imaging quality lets the diagnosis go wrong. Even a little distortion can route the pathologist away from the main cause of the disease. In this research work, the enhancement of dark ultrasound images has been done. An algorithm is developed using enhancement technique for nonuniform and uniform dark images. Finally, we compared the quality of the processed and unprocessed images. Both ETNUD and mean and median filtering techniques were used for image analysis.

Effect of Sinusoidal Excitation on Fluid Flow across a Cu-Mica Micro-Channel

Micro-fluidic devices integrated with on-chip control circuitry have been widely used in various biological and chemical synthesis applications. The objective of this paper is to investigate the effect of gravity, temperature, pulse width modulation (PWM) and sinusoidal excitations on the flow of methanol, ethanol and chloroform through an indigenously fabricated Cu-Mica micro-channel for automatic identification of fluids. For PWM vibrations, chloroform takes comparatively lesser time to flow across the given micro-channel that verifies that the velocity of the fluids is not a monotonic function of the PWM frequency. For sinusoidal excitations, ethanol exhibits maximum velocity around the frequency 1.5 KHz. The minimum velocity is shown at 4.5 KHz. For methanol, maximum Original Research Article Arya et al.; AIR, 4(4): 255-264, 2015; Article no.AIR.2015.080 256 velocity observed is around 2.5 KHz and minimum at 3.5 KHz. Chloroform shows no visible effect of excitation in its flow velocity. As velocity profile for a given set of influencing factors is fluid dependent, micro-channel based sensors may be developed for automatic identification of liquids.

Design and Fluid Structure Interaction Analysis of a Micro-Channel as Fluid Sensor

In this proposed work, the design and analysis of a flow sensor to be integrated into a micro-channel is presented. A finite element analysis is carried out to simulate fluid-structure interaction and estimate cantilever deflection under different fluidic flows at constant flow rate. The design of device is based on the determination of geometrical dimensions. A mathematical analysis describing the fluid mechanics and their interaction with the beam is also proposed. The mathematical model is done using finite-element analysis, and a complete formulation for design analysis is determined. Finite element method based Comsol Multiphysics simulations are used to optimize the design in order to determine the fluid velocities after interaction with the free end of the micro-cantilever beam. The device is successfully designed for sensing different fluids.

Synthesis of copper-ferrous (CuFe) nanowires via electrochemical method and its investigations as a fluid sensor

The special behaviour of nanowires with respect to electrical conductivity makes them suitable for sensing application. In this paper, we present a copper-ferrous (CuFe) nanowires based sensor for detection of chemicals. CuFe nanowires were synthesized by template-assisted electrochemical method. By optimizing the deposition parameters, continuous nanowires on a copper substrate were synthesized. The morphological and structural studies of the synthesized CuFe nanowires were carried out using scanning electron microscope (SEM) and X-ray diffraction (XRD). Substrates containing CuFe nanowires were moulded to form a capacitor. Different chemicals were used as dielectric in the capacitor which showed that the capacitance was a nonlinear function of the dielectric constant of fluid unlike the linear relation shown by conventional capacitors. This unique property of the nanowires based capacitors may be utilized for developing fluid sensors with improved sensitivity.