Siti Nooraya Mohd Tawil

Surface Morphology and Optical Properties of ZnO Films Synthesis Using Different Solvent

Zinc oxide (ZnO) is a promising electronic material for a variety of large area electronic applications including thin-film sensors, transistors, and solar cells. Various techniques have been focused and explored to synthesize ZnO films. In this study, sol-gel process was adopted as the fabrications process to grow the ZnO films. Three different types of solvents were used including ethanol, isopropanol and ethylene glycol as the reaction medium in the ZnO solution. The correlation between different solvents used and the properties of the ZnO films was explored and observed. The surface morphologies, structural and optical properties were examined using field émission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and ultraviolet-visible (UV-Vis) spectroscopy. Through the observation from FESEM results, the surface morphology changed when different solvents were used. The crystallographic structures of the ZnO films demonstrate high crystallinity, and the extracted crystallite size is around 30 nm. Furthermore, ZnO films synthesized using isopropanol and ethylene glycol exhibit high transmittance spectra greater than 80% in the visible region. In general, the experimental results revealed that different solvents in the sol-gel process exert influences on the properties of the ZnO films.

Influence of Gd Doping on the Structural and Optical Properties of ZnO

Doping transition metal or rare-earth metal ion are one of the most popular topics in semiconductors. In this work, gadolinium (Gd) doped zinc oxide thin films was prepared using spin-coating technique with different concentrations in atomic percent (at.%). The influences of rare-earth ions doped into the zinc oxide films were studies. The effects on the physical and optical properties of the films were investigated by field emission scanning electron microscope, x-ray diffraction, atomic force microscopic and ultraviolet-visible spectrophotometer. It was found that the properties of zinc oxide can be tuned by changing the concentration physical and optical of Gd.

Physical and optical studies on ZnO films by SOL-GEL

Zinc oxide (ZnO) is a new material used in electronics applications such as spintronics, diluted magnetic semiconductor (DMS) and thin films. In this paper, the findings in fabrication and characterization of ZnO nanoparticles are reported. ZnO thin films were deposited onto glass substrates using a spin coating techniques at different pre-annealing temperatures. The optical transmittance measurement of the ZnO nanostructures was examined using an ultraviolet-visible spectrophotometer (UV-Vis) with wavelength ranging from 300-800 nm. On the other hand, the topography and film roughness were, measured by an atomic force microscope (AFM). The surface morphologies was obtained using a field emission scanning electron microscope (FESEM) and showed that the ZnO nanoparticles are distributed uniformly.

2-channel defence Transcutaneous Electrical Stem Stimulator (DTES)

During the battle war, the usage of analgesic is considered to be the fast solution for pain relief. However, frequent usage without the risk of health damage is impossible. Therefore we developed the Transcutaneous Electrical Stem Stimulator device (DTES) that can operate based on the pulse generator circuit used to generate electric current in pulse form and later to be delivered to the pain area. This device is equipped with a digital timer so that the duration of treatment can be set by the user. An electric current is passed through the skin in between electrodes to stimulate the nerve where the pain is located. The passing electric current will inhibit the delivering of pain message to arrive at the brain thus user will not feel any pain at the affected area. The stimulation also will increase the production of endorphin, a natural pain killer inside human body to overcome the sensation of pain. The measured frequency and pulse duration were 6.519 KHz and 153.4μs represented there were 6519 cycle in a single second. Since the estimated frequency and pulse duration were 6.667 KHz and 150 μs respectively, the differences were 0.148 KHz and 3.4μs or 2.2% and 2.3% which are considered small and acceptable. The stimulated current is relatively small thereby it will not cause harmful effects to the user.

Synthesis and Characterization of Zinc Oxide Nanostructures by Different Sonication Period

Zinc oxide (ZnO) is a wide band gap semiconductor material (3.37 eV) with numerous present applications such as varistors, surface acoustic wave devices and future biomedical applications. ZnO nanorods were grown under specific growth condition by an inexpensive and simple, chemical bath deposition method on ZnO seeded glass substrates. Study of the ZnO nanorods over different precursors, i.e zinc acetate dehydrate and zinc nitrate hexahydrate, and sonication period ranging from 0 to 120 seconds by field emission scanning electron microscope (FESEM), including the nanorod size and the surface morphology, will be demonstrated in this paper. Characterization of the ZnO film using both X-ray diffraction (XRD) and UV-Vis spectroscopy will be established in determining the optimal composition along with the optical properties, respectively.

Effects of Ageing Time of ZnO Sol on Properties of ZnO Films by Sol Gel Spin Coating

In recent years, there are many techniques developed to synthesize zinc oxide (ZnO) films. However, among the synthesis methods available, sol-gel has the most advantageous which offers cost effective features. In the present work, ZnO films were prepared by solgel spin coating technique. The effects of solution ageing times which varies at 2h 15 min, 3h 30 min and 24h were investigated. The structural, morphological and optical properties were studied using an x-ray diffractometer (XRD, Bruker D8 Advance), atomic force microscope (AFM, Tenko XE-100) and ultra violet-visible spectrophotometer (UV-Vis, Shimadzu UV 1800), respectively. Based on the XRD measurement, it was revealed that ZnO films were polycrystalline with hexagonal wurtzite structure. The crystallite size is in the range of 34.4 ~ 28 nm which decreased with ageing time increment. On the other hand, the AFM analysis revealed that the surface roughness of the films increased due to the increment of ageing times. Optical transmittance spectra indicate that all films were transparent (>75%) in the visible range which slightly improved with increasing of ageing times. The optical band gap was estimated to be around 3.24 ~3.26 eV using Taucs plot. We revealed that the ageing time of ZnO sol influenced the material properties of ZnO films. Based on our finding we proposed that 24h ageing time is optimum for the fabrication of high quality ZnO films.

A database on the effect of magnetic fields on stem cells differentiation

The purpose of this work is to design a database software for storing the data taken from reviewed journals which is related to the effect of magnetic field (MF) on stem cells differentiation. The database facilitates in storing the data extracted from the journals. This without a doubt will help to minimize the time spent for collecting and organizing the data for future research reference. The software consists of two parts which are the Graphical User Interface (GUI) and database. The interface was designed using Microsoft Visual Basic 2010 software and the database was created using Microsoft SQL Express 2008 R2. The range of MF density that is already recorded in the database software is between 10μT to 16T. Every value of MF density recorded in the database software is also presented together with the influence of that MF density on stem cells differentiation. Besides, the source of stem cells used in the experiment and the differentiation results of those stem cells after exposed to MF are also noted in the database software. The result and analysis sections will enable the user to key in the important data regarding the experiment accomplished in the journals. As most of the researchers nowadays are working with the aid of computer, using the software database as an archive to store and organize the data from journals is expected to be very useful and convenient.

Piezoelectric Voltage Monitoring System Using Smartphone

This paper proposed to develop the voltage monitoring for piezoelectric system. The piezoelectric wireless monitoring system will enable voltage monitoring by utilizing a smartphone, piezoelectric sensor and Bluetooth to a device that installed with designated application. The Bluetooth system is the method used to connect the piezoelectric sensor and the smartphone. Thus, this research is aimed to monitor the voltage produced by the piezoelectric system wirelessly. The produced data can be monitored in real time as well as being extracted in excel data format for recording purpose. In the previous research, the piezoelectric were embedded in army boots for energy scavenging purpose to charge hand phone. Monitoring the voltage output utilizing multimeter not feasible at all, hence this research solves the challenges of monitoring the piezoelectric voltage output.

5-Channel defence transcutaneous electrical stem stimulator (5-channel DTES)

Analgesic normally used as a fast solution for pain relief. However, the over usage of the drug may result in harmful side effect. In the previous work, an alternative method replacing the usage of the drug were proposed known as 2 Channel Transcutaneous Electrical Stem Stimulator (DTES). However, the current DTES unable to vary the output level according to the patients level of pain. Hence, this paper proposes a new Transcutaneous Electrical Nerve Stimulator (TENS) with multiple variable output by referring the range for Peripheral Nervous System. This new method able to produce variable output compared to the previous 2-Channel DTES system. Although the waveform and more than 15% errors were recorded in this 5-channel DTES, still this project can be considered to be successful as its able to prove the 5-channel DTES is feasible in producing multiple output coherent to the patients level of pain. Since the system found to be feasible, with the suggested modification, its believed the 5-channel DTES able to perform better.

Viability of Controlling Prosthetic Hand Utilizing Electroencephalograph (EEG) Dataset Signal

This project presents the development of an artificial hand controlled by Electroencephalograph (EEG) signal datasets for the prosthetic application. The EEG signal datasets were used as to improvise the way to control the prosthetic hand compared to the Electromyograph (EMG). The EMG has disadvantages to a person, who has not used the muscle for a long time and also to person with degenerative issues due to age factor. Thus, the EEG datasets found to be an alternative for EMG. The datasets used in this work were taken from Brain Computer Interface (BCI) Project. The datasets were already classified for open, close and combined movement operations. It served the purpose as an input to control the prosthetic hand by using an Interface system between Microsoft Visual Studio and Arduino. The obtained results reveal the prosthetic hand to be more efficient and faster in response to the EEG datasets with an additional LiPo (Lithium Polymer) battery attached to the prosthetic. Some limitations were also identified in terms of the hand movements, weight of the prosthetic, and the suggestions to improve were concluded in this paper. Overall, the objective of this paper were achieved when the prosthetic hand found to be feasible in operation utilizing the EEG datasets.