International Journal of Nanoparticles (16 papers in press)
Thermomagnetic convection in a layer of magnetic nanofluid saturating porous medium with magnetic field dependent viscosity
by Amit Mahajan, Mahesh Sharma
Abstract: In this paper, the effect of magnetic field dependent (MFD) viscosity on the onset of thermomagnetic convection is examined for a horizontal layer of magnetic nanofluid (or ferrofluid) saturated porous layer. A model that comprises the effect of Brownian diffusion, thermophoresis, magnetophoresis, and Darcy's law is considered. We employed the Chebyshev pseudospectral QZ-method to solve the developed mathematical model and the results are derived for water-based and ester-based magnetic nanofluids. The effects of significant parameters are analyzed at the onset of convection in the gravity as well as in the microgravity environment. The influence of MFD viscosity, permeability parameter, the width of the fluid layer, Lewis number, Langevin parameter, particle concentration, and the concentration Rayleigh number at the onset of thermomagnetic convection are graphically illustrated.
Keywords: magnetic nanofluids; thermomagnetic convection; magnetic field dependent viscosity; microgravity; Darcy medium.
Synthesis of cadmium sulphide nanoparticles through liquid membrane pathway
by Sushma Chakraborty, Prabirkumar Saha
Abstract: This paper introduces a proof of concept that liquid membrane technology
that has always been used as a separation technique, can also be extended for
the generation of value added products in its downstream side. It is possible
to generate cadmium sulphide nanoparticles in the stripping phase of liquid
membrane separation unit which have wide industrial application such as
solar and photovoltaic cells. The process parameters such as concentration of
cadmium salt and pH in feed phase, concentration of strippant, concentration
of extractant/carrier agent etc. were optimized leading to maximum production
of CdS nanoparicles in the stripping phase. The characterization of CdS
nanoparticles were carried out using TEM, FESEM-EDX, FT-IR, XRD and
SAED. The nanosize and nanocrystalline nature of the CdS particles were
Keywords: Bulk Liquid Membrane; CdS nanoparticles; 1,10 Phenanthroline; TEM; FESEM-EDX; FT-IR; XRD; SAED.
Optimization of Carbon Nanotubes for Advanced Diagnosis and Biomedical Application
by Khalid Parwez
Abstract: Nanomaterials have a broad spectrum of applications in bioengineering and pharmaceutical fields, and carbon nanotubes (CNT) are among the most versatile and well-characterized members of this group of materials. The aim of this review is to discuss how CNTs can be exploited as diagnostic tools in various diseases. Various ways to functionalize the CNTs have been broadly discussed among which functionalization with antibodies has gained significance in recent years. Antibodies make their surface sensitive to surroundings which can be utilized in immuno-sensing. Surface passivation with other proteins is required to inhibit the non-specific binding of biomolecules on the hydrophobic carbon nanotube surface for ultrasensitive detection of biological species. The various intrinsic optical properties of SWCNT can be applicable in NIR-imaging of both in-vitro and in-vivo biological systems. They also have unique resonance-enhanced Raman signatures for Raman detection/imaging. CNT-based immuno-sensors provide very good results with a promising sensitivity and reproducibility and, in combination with novel devices (such as microfluidic electrochemical biosensor, Nanoelectromechanical systems (NEMS), Paper-based analytical devices (PADs), Field effect transistors (FET)), offer an attractive analytical approach for the fast, low-cost, and accessible detection of trace prognostic biomarkers, microbial pathogens, environmental pollutants and toxins.
Keywords: Nanomaterials; Carbon nanotubes; Functionalization; Biosensor; Immuno-sensor; FETs; MEMS; PADs; Tissue Engineering.
A Novel Approach for Computation of Cosine Function
by Abul Hasnat, Santanu Halder, Azizul Hoque, Debotosh Bhattacharjee
Abstract: Trigonometric function evaluation is required in almost all science and engineering applications. Objective of trigonometric function approximation in any digital systems are- faster computation in less number of clock cycles, optimizing hardware resource requirement for the circuit, accura-cy in more number of bits in the evaluated output etc. This study proposes a novel method for cosine function computation and its respective FPGA based architecture. In this method, a triangle is presumably located in the first quadrant of a circle with unit radius whose one vertex is the centre, other two vertices touches the perimeter of the circle. Using the area of the triangle, it is observed that the y coordinate of the third vertex of the triangle is the sine value. The error is difference between arch length and side length. Newtons interpolation method is used to formulate the error approximation function. Once the error is approximated, the value of the y co-ordinate is calculated. This method is implemented using VHDL, synthesized on Xilinx Spartan 3 xc3s200-5ft256 FPGA kit simulated on ModelSim 6.2c. The proposed architecture gives accuracy of the computed cosine value up to 14 bits or more in 96% cases in eleven clock cycles only. The proposed architecture operates as fast as 89.977 MHz.
Keywords: Triangle; Unit Circle; FPGA; CORDIC; Sine; Cosine; Newoton’s Interpolation.
Application of aqueous phase CdSe quantum dots for formaldehyde sensing
by Deepika, Rakesh Dhar, Suman Singh
Abstract: Thioglycolic acid capped cadmium selenide (CdSe) quantum dots have been synthesised in aqueous phase and their optical properties have been studied using UV-visible absorption and fluorescence spectroscopy. Quantum dots have been characterised using TEM and XRD. The potential application of CdSe quantum dots are further studied using formaldehyde as a model compound. The sensing is based on fluorescence quenching of quantum dots in the presence of formaldehyde, and this work showed linearity in the range from 0.15 to 1.05 ppm, with a detection limit of 0.06 ppm.
Keywords: quantum dots; aqueous phase; optical property; spectroscopy.
Methotrexate sodium loaded Tween 80 stabilised gold nanoparticles: synthesis and characterisation
by Ankita U. Patel, Girish K. Jani, Ketan Ranch, Akshay Koli, Naresh B. Dharmani
Abstract: Cancer is a disease characterised by uncontrolled multiplication and spread of abnormal forms of the body's own cells. Methotrexate sodium is an antineoplastic agent of the anti-metabolite class of chemotherapy drugs, which inhibits dihydrofolate reductase and blocking the conversion of dihydrofolic acid to tetrahydrofolic acid. Metal nanoparticles such as gold nanoparticles are having a smaller size, more stable and relatively narrow size distribution which provide opportunities for effective active or passive targeted delivery. Thus, the gold nanoparticles were synthesised using a chemical reduction method, involving the reduction of chloroauric acid by trisodium citrate, stabilised by Tween 80 and Methotrexate sodium was loaded on to it. Physical observations and FTIR analysis showed that drug and excipients pass the drug-excipient compatibility study. The present work reports a significant and a simple, process capable of synthesising size-controlled Tween 80 stabilised gold nanoparticles rapidly under ambient conditions.
Keywords: cancer; chloroauric acid; gold nanoparticles; Methotrexate sodium; trisodium citrate; Tween 80.
Calculating current density and quantum efficiency of p-n junction solar cell with quasi-Fermi level approximation
by Arpan Deyasi, Angsuman Sarkar
Abstract: Current density and quantum efficiency of p-n junction GaAs solar cell is analytically investigated incorporating the effect of excess carriers due to photon incidence. Carrier transport equations for both types of carriers are solved involving both the conduction mechanisms along with generation rate. Change of dark current is reported in presence of varying operating conditions, and modulation of quantum efficiency is obtained by varying structural parameters. Results are useful for accurate estimation of figure of merit, which will play key role in photovoltaic applications.
Keywords: current density; quantum efficiency; quasi-Fermi level; doping concentration; temperature; photon flux.
Synthesis, characterisation and investigation of enhanced photocatalytic activity of Sm+3, Ni+2 co-doped TiO2 nanoparticles on the degradation of azo dyes in visible region
by Amna Bashir, Fatima Bashir, Zahid Mehmood, Muhammad Sultan Satti, Zareen Akhter
Abstract: Pure and samarium-nickel co-doped TiO2 nanoparticles with different Sm contents were synthesised by sol-gel method. The synthesised nanoparticles were characterised using different techniques. It is revealed from experimental results that the doping of TiO2 with samarium and nickel not only increase the surface area of mesoporous TiO2 but also decrease the particle size (17.0 nm to 8.01 nm by increasing Sm+3 contents). Diffuse-reflectance spectroscopic studies showed the slight red shift in band-gap transitions and appearance of the new absorption band in the visible region (719 nm) caused by Ni+2 and Sm+3 doping. The photocatalytic degradation of azo dyes (Reactive Red-195 and Reactive Black-08) was carried out in visible region using modified TiO2 at different pH values. Results revealed that 99% of RR-195 and 75.33% RB-08 were degraded after 10-20 minutes of irradiation. Maximum degradation was achieved in case of nanoparticles co-doped with 5% Ni and 3% Sm.
Keywords: catalysis; metal oxides; degradation; chemical oxygen demand; COD; Azo dyes; synergistic effect.
The role of pH and effect of calcination temperature on polymorphs and properties of iron oxide nanoparticles
by J. Sharmila Justus, S. Dawn Dharma Roy, A. Moses Ezhil Raj, M. Bououdina
Abstract: Iron oxide nanoparticles were successfully synthesised by a facile solution approach employing iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent, followed by calcination in air at different temperatures viz. 400, 600 and 800°C for three hours. The range of calcination temperature has been chosen from thermogravimetry analysis. X-ray diffraction patterns clearly confirmed the structural transformation of cubic Fe3O4 to hexagonal α-Fe2O3 upon calcination. FTIR vibrational bands corresponding to Fe-O bondings in the tetrahedral and octahedral sites and their shift upon calcination confirmed the structural transitions. Scanning electron microscopy observations revealed agglomers meanwhile energy dispersive spectroscopy analysis confirm the elemental composition. Optical band gaps estimated from Tauc plots was found to vary with structural transformation. Electrical conductivity measurements with temperature were explained on the basis of fluctuation of ions in the B sites of Fe3O4 and deviation from stoichiometry in the case of α-Fe2O3.
Keywords: magnetic materials; nanoparticles; iron oxide; Fourier transform infrared spectroscopy; electron microscopy; optical properties; electrical conductivity.
Special Issue on: DevIC 2017 Nanotechnology and High-Speed Electronic Systems
Optimization of fully depleted SiGe channel with raised source/drain buried oxide nMOSFET
by K. VANLALAWMPUIA, Brinda Bhowmick (Shome), Madhuchhanda Choudhury
Abstract: A fully depleted silicon-germanium (SiGe) n-channel heterojunction MOSFET with raised buried oxide in the source/drain is reported under the consideration that channel is made of SiGe and source/drain regions is made of Silicon (Si). Due to the raised buried oxide source/drain region, it provides better current due to the improvement of mobility in the channel region and also reduce the surface scattering effects. Bandgap engineering has been done to improve the electrical behavior of the device. Simulation work for different parameters on the device has been carried out and presented in the paper. The electrical characteristics of the proposed device is optimized by varying the device dimensions. Effect of mole fraction on threshold voltage (VTH), Subthreshold swing (SS), ION and IOFF Current ratio is analyzed. It is observed that due to presence of SiGe channel and the raised source/drain, the proposed device shows enhancement in electrical characteristics. A CMOS inverter through proposed device has been implemented and the effect of mole fraction on its characteristic is reported. Average delay increases as mole fraction increases.
Keywords: SiGe channel; fully depleted; buried oxide.
Reduced Ordered Binary Decision Diagram based Combinational Circuit Synthesis for Optimizing Area, Power and Temperature
by Apangshu Das, Akash Debnath, Sambhu Nath Pradhan
Abstract: At sub-micron technology, temperature plays an important criterion to design a VLSI circuit. With the increase of functionality demand, component density in integrated circuit increases resulting in the increase of reliability issues, such as increases in power-density. The temperature of an integrated circuit is directly proportional to the power-density. Excessive temperature generation highly affects the yield of the circuit. To limit the temperature rise, power-density is to be minimized. However, reduction of power and power-density increases the area. So, there is a trade-off among area, power, and power-density. In this paper, an attempt is made to tackle the rise in circuit temperature by optimizing power-density (and of course considering trade-off with power and area) during logic synthesis level, keeping in mind that thermal-aware realization with data structure manipulation and power reduction technique can solve the problem of temperature rise. Reduced Ordered Binary Decision Diagram (ROBDD) being canonical in nature and having node reduction capability by proper variable ordering makes a suitable choice of logic realization in this work. ROBDD is used here not only to reduce area (node) but also the possibility of reducing power and temperature (power-density) is explored. Variable ordering is done using Genetic Algorithm (GA). In this work, a genetic algorithm based approach is presented to determine a suitable variable ordering during the formation of the ROBDD for its thermal-aware realization considering other parameters like area and power without performance degradation. Proposed approach shows more than 33% savings in area and power, and 5.61% savings in power-density with respect to initial ROBDD representation of LGSynth93 benchmark circuits. Actual on-chip area, power dissipation and the absolute value of temperature are calculated using CADENCE and HotSpot tool to validate the power-density based results.
Keywords: BDD; ROBDD; Area power power-density trade-offs; Genetic Algorithm; variable ordering; Temperature; HotSpot.
Nanoscale T Shaped AlGaN/GaN HEMT with Improved DC and RF Performance
by Meryleen Mohapatra, Tanmoy De, Ajit Kumar Panda
Abstract: In this research work, two AlGaN/GaN based HEMT with different gate structure are designed. The first one is normal rectangular shaped HEMT with a gate length of 150nm and another one is T shaped HEMT with a gate foot print of 90nm. A comparison is done for the obtained results of both the HEMTs. It is shown that the DC parameters like drain current, transconductance are improved for T shaped HEMT as compared to normal gate HEMT. Coming to the RF performance, the maximum cut-off frequency of the normal gate HEMT is 24GHz at the drain voltage of 20V and the gate voltage of 2V whereas the maximum cut-off frequency of the T-shaped gate HEMT is 47GHz at the same drain and gate voltage. For T-shaped HEMT, it is observed that maximum cut-off frequency is double of the normal gate HEMT. Maximum frequency of oscillation for normal gate HEMT is 95GHz and for T-shaped gate HEMT it is 115GHz at same drain and gate voltage i.e. 2V and 20V. At the operating frequency of 5GHz, the minimum noise figure of the normal gate HEMT is 0.13dB. At the same operating frequency the minimum noise figure of the T-shaped gate HEMT is 0.05dB. Intrinsic time delay is calculated for both the device. Intrinsic time delay of normal gate HEMT is 22ps where as the intrinsic time delay for T gate HEMT is 12ps. These results prove that the DC and RF performance of a T-shaped gate HEMT is much better than a normal gate HEMT and so the T-shaped gate HEMT is more preferable for high frequency operations like radar communication, satellite communication, wireless communication etc.
Keywords: High Electron Mobility Transistor; Cut-off frequency; Intrinsic time delay.
Electrical parameter analysis of gate-extension on source of germanium tri-gate FinFET
by Rajashree Das, Srimanta Baishya
Abstract: This paper presents the impact of geometrical and the electrical parameters such as the concentration in channel region, variation of temperature, drain potential, gate work function, and electrostatic potential on the electrical characteristics of Germanium (Ge) FinFET with two stacked gate dielectrics overlap on the source. The presented device exhibits better performance in terms of ION, IOFF, and ION/IOFF compared to the conventional FinFET structure.
Keywords: Dual dielectric; FinFET; Germanium; Silicon; Source overlap.
Impact of structural parameters on DC performance of recessed channel SOI-MOSFET
by Sikha Mishra, Urmila Bhanja, Guru Prasad Mishra
Abstract: With the concept of groove gate and implementing the idea of silicon on insulator, a new analytical model is developed for the RRC-SOI (rectangular recessed channel silicon on insulator) MOSFET. This analytical model is formulated using 2-D Poissons equation and develops a compact equation for threshold voltage using minimum surface potential. This paper analyses the effect of negative junction depth on device parameters, such as minimum surface potential, threshold voltage, sub-threshold slope, and drain induced barrier lowering. The impact of oxide thickness variation on the above parameters has also been evaluated. Further, the linearity performance in terms of figure of merits and device parameters like drain current and trans-conductance of the proposed model is compared with the simulated results of RRC (rectangular recessed channel) MOSFET. The validity of the proposed model has been verified with simulation results performed on Sentaurus TCAD device simulator.
Keywords: Short-channel effects (SCE); silicon-on-insulator (SOI); rectangular recessed channel (RRC); negative junction depth (NJD).
Electro-Thermal Assessment of Heterojunction Tunnel-FET for Low-Power Digital Circuits
by Tara Prasanna Dash, Sanghamitra Das, Suprava Dey, C.K. Maiti
Abstract: To overcome the fundamental limitations of conventional MOSFETs, tunneling field effect transistors (TFETs) with strained-SiGe channel (via heterogeneous integration) may be used and is demonstrated using TCAD simulations. We mainly focus on the design and implementation of silicon-germanium (SiGe) based tunnel field effect transistor, aiming to reduce the device operation voltage down to below 0.5V. Physics-based electro-thermal simulations are performed for evaluating the self-heating (temperature rise) in the devices. We present the results of the electro-thermal analysis supported by effective 2D and 3D device simulations. Performance improvement in drain current as high as 200% has been achieved.
Keywords: Heterostructure Tunnel FET; strained-SiGe; Heterogeneous Integration; Electro-thermal simulation.
Analysis and Circuit Sizing Performance of a Differential amplifier using HPSO Algorithm
by LISON CHABUNGBAM SINGH
Abstract: This paper presents an analysis of thermal noise of differential amplifier and automated sizing procedure with thermal noise incorporation, in addition to various design specifications, as constraints in the design process. Human Behavior-Based Particle Swarm Optimization (HPSO), a Swarm Intelligence (SI)-based optimization algorithm is used to perform the sizing task to obtain optimal value of design variables value subject to a satisfying set of constraints, with the main objective of designing a Low-noise amplifier with minimum circuit area. The presented design procedure gives an option of considering both width and length of MOS transistor as design variables, which in turn can tune trade-off circuit performance parameters. The computational analysis is performed in MATLAB and CADENCE tool with UMC 180 nm parameters technology is used to validate the presented design procedure. Further, the performance of the purposed automated design methodology is compared with previous design methodology to check its efficiency in terms of speed, time and robustness.
Keywords: HPSO; Differential amplifier; Thermal noise; Area Optimization; Circuit Sizing.