Shahzadi Tayyaba

Micro Electromechanical Systems (MEMS) Based Microfluidic Devices for Biomedical Applications

Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications.

Annealing temperature effect on structural, morphological and optical parameters of mesoporous TiO2 film photoanode for dye-sensitized solar cell application

Abstract Use of Degussa P25 titanium-dioxide nanopowder in dye-sensitized solar cell (DSSC) photoanode improves efficiency of the DSSC cell. Annealing of titanium dioxide is required for fabrication of crystalline mesoporous thin film photoanode on transparent conducting glass using doctor blade method. Different annealing temperatures provide different structural, morphological, and optical properties of the photoanode, which may influence the efficiency of the cell. In this paper, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and UV-Vis-NIR spectroscopicanalysis have been carried out to investigate annealing temperature effect on various structural parameters, mole-fraction, phase-content, and optical bandgap of the TiO2 film photoanode. It was observed that depending on annealing temperature, theratio of polymorphs of Degussa P25 changed substantially. For the change in annealing temperature from 350 °C to 600 °C, variations occurred in crystallite size from 11.9 nm to 24.9 nm, strain from 0.006 to 0.014, specific surface area from 62.77 m2·g-1 to 125.74 m2·g-1, morphology index from 0.49 to 0.64, dislocation density from 5 × 1013 line/m2 to 8 × 1015 line/m2, crystallite per unit surface area from 2 × 1013 m-2 to 2.5 × 1014 m-2, and optical bandgap from 2.4 eV to 3.1 eV.

Influence of natural dye adsorption on the structural, morphological and optical properties of TiO2 based photoanode of dye-sensitized solar cell

Abstract Porous photoanodes of dye-sensitized solar cells (DSSCs) can adsorb specific type of natural or organic dyes. Adsorption of the dye results in a change of the structural, morphological and optical characteristics of the photoanode. In this work, we present a comparative study on the adsorption effect of natural dye (Curcuma Longa sp.) on the structural, morphological and optical properties of mesoporous titanium dioxide (TiO2) photoanode on indium tin oxide (ITO) coated glass. A number of investigations including XRD, UV-Vis spectroscopy, EDS, and SEM were carried out to observe the variations due to adsorbed dye on TiO2 surface. XRD characterization revealed the effect of dye adsorption on specific surface area (SSA), crystallite size, and morphological index (MI). In this case, increasing SSA with decreasing particle size was found for both dye adsorbed and dye free DSSC photoanode samples. Also, the MI and SSA were found to be directly and inversely proportional to the crystallite size respectively. UV-Vis-NIR spectroscopy showed that dye adsorption changes the light absorption, transmittance, and optical bandgap of the photoanode. Average atomic mass percentage of titanium (Ti) and oxygen (O) obtained from EDS analysis proved the presence of TiO2 in the mesoporous photoanode. In SEM images, significant morphological changes of mesoporous TiO2 surface appeared because of dye adsorption.

Efficiency enhancement of natural dye sensitized solar cell by optimizing electrode fabrication parameters

Abstract Efficiency of dye-sensitized solar cell (DSSC) depends on several interrelated factors such as type and concentration of dye, type and thickness of photoelectrode and counter electrode. Optimized combination of these factors leads to a more efficient cell. This paper presents the effect of these parameters on cell efficiency. TiO2 nanoporous thin films of different thicknesses (5 μm to 25 μm) were fabricated on indium doped tin oxide (ITO) coated glass by doctor blading method and characterized by inverted microscope, stylus surface profiler and scanning electron microscope (SEM). Natural organic dye of different concentrations, extracted from turmeric, was prepared with ethanol solvent. Different combinations of dye concentrations and film thicknesses along with different types of carbon catalyst have been investigated by I-V characterization. The result shows that the cell made of a counter electrode catalyst material prepared by candle flame carbon combined with about 15 μm thick photoelectrode and 100 mg/mL dye in ethanol solvent, achieves the highest efficiency of 0.45 %, with open circuit voltage of 566 mV and short circuit current density of 1.02 mA/cm2.

Factors influencing the Cloud Computing adoption in Higher Education Institutions of Punjab, Pakistan

Cloud Computing is one of the most important trend and newest area in the field of information technology in which resources (e.g. CPU and storage) can be leased and released by customers through the Internet in an on-demand basis. The adoption of Cloud Computing in Education and developing countries is real an opportunity. Although Cloud computing has gained popularity in Pakistan especially in education and industry, but its impact in Pakistan is still unexplored especially in Higher Education Department. Already published work investigated in respect of factors influencing on adoption of cloud computing but very few investigated said analysis in developing countries. The Higher Education Institutions (HEIs) of Punjab, Pakistan are still not focused to discover cloud adoption factors. In this study, we prepared cloud adoption model for Higher Education Institutions (HEIs) of Punjab, a survey was carried out from 900 students all over Punjab. The survey was designed based upon literature and after discussion and opinions of academicians. In this paper, 34 hypothesis were developed that affect the cloud computing adoption in HEIs and tested by using powerful statistical analysis tools i.e. SPSS and SmartPLS. Statistical findings shows that 84.44% of students voted in the favor of cloud computing adoption in their colleges, while 99% supported Reduce Cost as most important factor in cloud adoption.

Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC) for Implant of Varicose Veins

Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT), vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s) and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs.

Comparative simulation of silicon, PDMS, PGA and PMMA actuator for piezoelectric micropump

Microelectromechanical system (MEMS), a technology of miniature devices comprises micropumps that are also crucial components in microfluidic analysis systems. This article provides comparative study that focused on numerical simulation of silicon, Polydimethylsiloxane (PDMS), Polymethyl methacrylate (PMMA) and Polyglycolic acid (PGA) actuator for piezoelectric micropump in order to determine which one is better. The aim and objectives of this study is to exhibit the usefulness of finite element analysis (FEA) and simulation techniques for selecting a better material for membrane attached on an actuator in a piezoelectric micropump. The piezoelectric micropump consists of actuator having piezoelectric disk coupled on membrane that can be made of different materials like silicon, PDMS, PMMA and PGA. The behavior of actuator like deflection and stress for different materials has been analyzed by applying voltage from 50 V to 150 V for varying frequency 50 Hz to 150 Hz. The maximum deflection at 150 V has been found for PGA that is 67 μm and minimum deflection comes out for silicon that is 16 μm while others PDMS has deflection of 25.2 μm and PMMA has deflection of 25.8 μm. This research work offers helpful information for piezoelectric micropump design.

Effect of Buckling Restrained Braces Locations on Seismic Responses of High-Rise RC Core Wall Buildings

Conventionally, a flexural plastic hinge is designed and detailed at the core wall base and coupling beams ends to control the seismic responses. This strategy is based on allowing the damage to be concentrated on main structural components. To avoid such damage, an alternative strategy using energy dissipating devices (EDDs) such as buckling restrained braces (BRBs) is being studied and implemented nowadays. In this study, effect of BRBs locations on forty- (40-) story high-rise RC core wall case study building has been studied in detail using Nonlinear Response History Analysis (NLRHA) for seven spectrally matched ground motions. BRBs have been installed at critical locations identified with respect to the maximum DBE elastic modal racking shear deformation demands and force (shear and moment) demands in three different options. The force, deformation, and energy demands on structural components are compared for conventional design and different options of BRBs. The comparison with conventional design shows that BRBs not only are effective for reducing shear force demand along wall height, bending moment demand at mid height, and deformation demands by 10%, 45%, and 45%, respectively, but significantly reduce the rotation and energy demands in the core wall by 90% and 250%, respectively.

Sinusoidal Microchannel with Descending Curves for Varicose Veins Implantation

Approximately 26% of adult people, mostly females, are affected by varicose veins in old age. It is a common reason for distress, loss of efficiency, and worsening living conditions. Several traditional treatment techniques (sclerotherapy and foam sclerotherapy of large veins, laser surgeries and radiofrequency ablation, vein ligation and stripping, ambulatory phlebectomy, and endoscopic vein surgery) have failed to handle this disease effectively. Herein, authors have presented an alternative varicose vein implant method—the descending sinusoidal microchannel (DSMC). DSMC was simulated by Fuzzy logic MATLAB (The MathWorks, Natick, MA, USA) and ANSYS (ANSYS 18.2, perpetual license purchased by Ibadat Education Trust, The University of Lahore, Pakistan) with real and actual conditions. After simulations of DSMC, fabrication and testing were performed. The silver DSMC was manufactured by utilizing a micromachining procedure. The length, width, and depth of the silver substrate were 51 mm, 25 mm, and 1.1 mm, respectively. The measurements of the DSMC channel in the silver wafer substrate were 0.9 mm in width and 0.9 mm in depth. The three descending curves of the DSMC were 7 mm, 6 mm, and 5 mm in height. For pressure, actual conditions were carefully taken as 1.0 kPa to 1.5 kPa for varicose veins. For velocity, actual conditions were carefully taken as 0.02 m/s to 0.07 m/s for these veins. These are real and standard values used in simulations and experiments. At Reynolds number 323, the flow rate and velocity were determined as 1001.0 (0.1 nL/s), 11.4 cm/s and 1015.3 (0.1 nL/s), 12.19 cm/s by MATLAB (The MathWorks, Natick, MA, USA) and ANSYS simulations, respectively. The flow rate and velocity were determined to be 995.3 (0.1 nL/s) and 12.2 cm/s, respectively, at the same Reynolds number (323) in the experiment. Moreover, the Dean number was also calculated to observe Dean vortices. All simulated and experimental results were in close agreement. Consequently, DSMC can be implanted in varicose veins as a new treatment to preserve excellent blood flow in human legs from the original place to avoid tissue damage and other problems.

Simulation of fuzzy based flow controller in ascending sinusoidal microchannels

The reason of significance of sinusoidal microchannels is their biomedical applications. The flow rate is affected with the change in pressure, radius and channel length. In this study, the simulation of fluid flow in ascending sinusoidal channels has been presented by applying the Fuzzy Logic Control system. The Mamdani model in MATLAB is utilized to investigate the rate of flow of the fluid for changing the radius, pressure and channel length. For this control system Hagen-Poiseuille equation is used in order to generate the fuzzy rules. This study provides valuable facts to develop a fluid control system on the basis of fuzzy logic for ascending sinusoidal microchannel. The difference between the percentage error in MATLAB simulation and the formulated rate of flow is 0.04%. That confirms the precision of this designed model.