Sushanta Kumar Kamilla

Formation of chelating agent driven anodized TiO2 nanotubular membrane and its photovoltaic application

Titania (TiO(2)) nanotubular arrays provide an exciting material for dye sensitizing solar cells (DSSC) because of their large surface area, lower recombination losses, and fast charge transport properties along the nanotubes. In this paper, design of a next generation DSSC using a TiO(2) nanotubular membrane is discussed. A single step, green process is developed to produce stable large area, free-standing TiO(2) nanotubular films (in a short time, 30-60 min) by anodizing Ti using an organic electrolyte, containing disodium salt of ethylene diaminetetraacetic acid (Na(2)[H(2)EDTA]) as complexing agent, and subsequent drying. Transparent, crack-free TiO(2) films, 20-41 microm thick containing ordered hexagonal TiO(2) nanotubes are achieved by this process. Films having a geometrical area up to 16.5 cm(2) with pore openings of 182 nm have been obtained. These films have been etched to form membranes which provide an exciting prospect for front side illuminated DSSC with good mass and photon transport properties as well as wettability. A photovoltaic efficiency of 2.7% is achieved using a front side illuminated DSSC compared to 1.77% using back side illumination.

Experimental and simulated study of electrical behaviour of ZnO film deposited on Al substrate for device applications

Abstract In this paper, zinc oxide (ZnO) film has been deposited on Al substrate by chemical wet and dry technique which is just a simple modified version of the dip coating method. In this method, it is possible to precisely control the immersion and withdrawal speed, with drying as well as annealing at the same time. The polycrystalline nature of ZnO has been confirmed by X-ray diffraction (XRD) analysis. The XRD analysis clearly indicates that some percentage of Al diffuses into the ZnO matrix at its interface region; hence it affects mobility of the sample. Hall measurement indicates the ZnO semiconductor as n-type. I–V characteristic of the sample shows that the contact is Ohmic and it can be used as a sensor at low potential value. The mobility decreases with increase in temperature. The simulation study carried out for I–V and mobility through simulation using ATLAS (SILVACO) software confirms that the experimental and simulation results are in close agreement with respect to the I–V characteristic and the mobility.

Performance of a human eye in coherent illumination

The modulation of a periodic object with infinitely thin lines by a human eye in presence of Stiles-Crawford effect of the first kind is insensitive to coherent illumination.

Characterisation of bulk GaSb using TCAD

The III–V compounds have turned out to be promising candidates for high speed electronics and photonic devices. Among III–V compounds, gallium antimonide (GaSb) is particularly interesting as a substrate material because its lattice parameter matches solid solutions of various ternary and quaternary III–V compounds whose band gaps cover a wide spectral range. These have stimulated a lot of interest in GaSb for basic research in materials as well as device fabrication. In this paper, investigation is done for the hole transport property of bulk GaSb with intrinsic concentration 1.5×1015 cm−3. Hole concentration and mobility of bulk GaSb were investigated by simulation method using the device simulation software ATLAS (SILVACO) in the temperature range from 77K to 320K in an interval of 5Kand 10K. It also shows that the effective hole mobility is about 461 cm2/Vs with the concentration ≈ 1.5 × 1015 cm−3 at room temperature i.e. 300K. It has been found that the effective mobility is affected by ionized impurity scattering; in contrast at higher temperatures (≈ 300K) acoustic, polar optical and non-polar optical scattering processes dominate the mobility. The agreement of simulated data with that of reported experimental data is found to be satisfactory.

Performance analysis of ZnO-based ultrasonic MEMS transducer used for blind person navigation

Navigation is not an easy task especially without using eye. Creatures like bats and dolphins are navigated by creating ultrasonic wave. The sensory organs help them to create and sense the path without visualising it. This paper imitates these creatures to propose an ultrasonic-based MEMS transducer for blind person navigation. MEMS-based acoustic transducers commonly employ the piezoelectric material. This model has been designed by using non-toxic and low cost compound like zinc oxide (ZnO) using COMSOL multiphysics. 2D axis-symmetrical model geometry is designed to imitate like sensory organ to sense the obstacle present two metres away from it. An optimised voltage of five volts and frequency of 20.103 KHz is applied to the proposed model to create ultrasonic wave. Further, the wave propagation in the air medium is analysed by using 3D partial differential equation. The pressure waves are studied during transmitting and receiving time. The rebounded wave from the obstacle to the transducer is converted to 30.2 mV by the proposed model. The von-misses stress is carried out to study the pressure on transducer surface.

Preparation of TiO 2 film on Ag and Al electrode for electrochemical bio-sensing application

In this present, work, titanium dioxide (TiO2) deposited on Ag and Al electrodes were fabricated by sol-gel chemical wet and dry (CWD) method to detect urea. The formation of the polycrystalline TiO2 deposited on Ag and Al substrates were confirmed by X-ray diffraction (XRD) analysis. The XRD analyses of both the samples clearly indicated that some percentage of Ag and Al diffuses into the TiO2 matrix at its interface region. The nature of I-V characteristics showed by the TiO2 on Ag and Al wire electrodes are found to be Ohmic and is perfect to be used for electrochemical sensor or bio-sensor at very low potential value. The performance and response to various concentrations of urea solution and pH level were experimentally studied by using TiO2 coated on Ag and Al as working electrodes with respect to Ag as reference electrode.

Forecasting Hydrogen Fuel Requirement for Highly Populated Countries Using NARnet

Petroleum is being consumed at a rapid pace all over world, but the amount of petroleum is constant in earth crust and production to consumption requirement is not up to mark. It is expected that a day may come when this world will witness the crisis of this oil. For this our paper addresses the prediction of petroleum crisis in two most populated country of the world i.e. India and China using novel Artificial Neural Network (ANN) based approach. The set of observation comprising three features like population, petroleum production and petroleum consumption are being considered to design the predictive model. Our work shows that petroleum production over consumption with respect to sharp increase of population, leads to a decisive issue in production of an alternative fuel like Hydrogen fuel. In our analysis, we used the data provided by different government sources over a period of more than 30 years and then simulated by a multistep ahead prediction methodology, i.e. nonlinear autoregressive Network (NARnet) to predict petroleum crisis in near future. The results of present study reveals that for India, the Normalized Mean Square Error (NMSE) values found for population petroleum production and consumption are 0.000046, 0.2233 and 0.0041 respectively. Similarly for China the corresponding values are 0.0011, 0.0126 and 0.0041 respectively, which validates the accuracy of the proposed model. The study forecasts that by 2050 hydrogen fuel may be a suitable replacement for petroleum, and will not only reduce pollution, but also enhance the fuel efficiency at lower cost as compared to that of petroleum.

A Simulation Approach to Study the Effect of Ultrasonic MEMS Based Receiver for Blood Glucose Sensing Applications

The accurate measurement of glucose level in the blood is an important task to prevent the progression of chronic disease like diabetes mellitus. This article proposes a simulation based approach to evaluate the ZnO-based ultrasonic piezoelectric microelectronics mechanical systems (MEMS) receiver for blood glucose sensing applications. Prior to the fabrication of the proposed biosensor, a simulation study is conducted to avoid the dissipation of valuabletime and cost. The potential of 1.6V with a 350-MHz frequency is applied to the transmitter section that has been placed on the surface of blood sample with a cylindrical geometry having diameter and height of 1 and 10mm, respectively. The surface and the radial displacement of the receiver section structure of the piezoelectric material with pressure and stress are studied in the blood medium. The simulation results reveal that, for different glucose density levels in the human blood, different pressure values are observed at the receiving end and that the respective pressure values are converted into voltages by using the piezoelectric principle. To verify the changes in the generated voltages, we have compared the glucose levels of blood samples using the proposed approach with the commercially available glucometer.

Validity of Application of Rayleigh's Limit of Resolution in Presence of Defocus Wavefront Errors

In the field of image science, Rayleigh criterion of resolution has been and is still being extensively used in the assessment of performance of optical imaging systems including telescopes. This is in spite of the fact, that Rayleighs criterion is applicable in incoherent illumination and it loses its validity in the presence of atmospheric turbulence, various types of wavefront degrading factors, image motion etc. In the present paper, we have discussed the validity of application of Rayleighs criterion to the resolution of Binary Stars of unequal brightness due to defocus wavefront errors.