Aliza Aini Md Ralib

Finite element modeling of SAW resonator in CMOS technology for single and double interdigitated electrode (IDT) structure

The performance of surface acoustic wave resonator in CMOS technology for single and double electrode (IDT) structure is presented. Interdigitated electrodes (IDT) structure in surface acoustic wave (SAW) resonator is the most crucial component for excitation of SAW devices. Possible configurations for the IDT are single electrode and double electrode. The performance of the resonator for single and double electrode is compared at a frequency range of 0.5 GHz to 1 GHz. 2D Finite element modeling of the CMOS SAW resonator was simulated using COMSOL Multiphysics® for three step analysis eigen frequency, frequency domain and time domain analysis. The structure and dimension of the device is based on 0.18 μm RF CMOS process where the pattern of IDT is fabricated using standard CMOS fabrication process. The simulated results shows high quality factor in the order of thousands for double electrode CMOS SAW resonator compared to single electrode CMOS SAW resonator.

Theoretical modeling and simulation of MEMS piezoelectric energy harvester

Energy harvesting devices, capable of converting wasted ambient energy to electrical power are rapidly gaining popularity as a source of green and renewable energy. This work presents the design and simulation of MEMS based piezoelectric cantilever beam which can both harvest energy as well as monitor critical vibration frequencies in power plant gas turbines. The design of the energy harvesters consists of a cantilever beam structure with the interdigitated electrodes on the zinc oxide piezoelectric layer with nickel proof mass at the end of the beam. A mechanical finite element simulation was conducted using CoventorWare¯. This paper illustrates the proposed theoretical modeling and simulation of piezoelectric energy harvesters.

Dependence of preferred c-axis orientation on RF magnetron sputtering power for AZO/Si acoustic wave devices

We report the deposition of high quality c-axis oriented Aluminium doped Zinc Oxide (AZO) on silicon substrate for surface acoustic wave (SAW) applications. AZO thin film is prepared by Radio frequency magnetron sputtering method. Sputtering is a preferred method because it is able to perform deposition at low temperature, produce uniform thin film and possesses high deposition rates. In preserving the functionality of the device during post CMOS process, low deposition temperature is crucial. In order to obtain the preferred AZO structural properties with strong acoustoelectric interaction, we investigate the influence of RF power on c-axis preferred orientation of AZO/Si multilayer. The deposited thin films are characterized by X-Ray diffractometer and scanning electron microscopy (SEM). The crystal structures are evaluated in terms of c-axis lattice constant, d-spacing and crystallite size. It is observed that as RF power increases, the AZO film is predominantly oriented at c-axis (002) and achieved high crystalline quality. However, if the applied RF power is too high, the energized ions would impede the growth of high quality film. The optimum RF power was found to be at 250 W, at which the material exhibits hexagonal wurtzite-type lattice of ZnO structure, high crystallinity (lowest FWHM value) and crystallite size, and high deposition rate.

Verification of Quartz Crystal Microbalance Array using Vector Network Analyzer and OpenQCM

Received Jan 15, 2018 Revised Mar 14, 2018 Accepted Mar 30, 2018 Blood veins detection process can be cumbersome for nurses and medical practioners when it comes to special overweight type of patients. This simple routine procedure can lead the process into an extreme calamity for these patients. In this paper, we emphasized on a process for the detection of the vein in real time using the consecrations of Matlab to prevent or at least reduce the number of inescapable calamity for patients during the infusion of a needle by phlebotomy or doctor in everyday lives. Hemoglobin of the blood tissues engrossed the Near Infrared (NIR) illuminated light and Night vision camera is used to capture the scene and enhance the vein pattern clearly using Contrast Limited Adaptive Histogram Equalization (CLAHE) method. This simple approach can successfully also lead to localizing bleeding spots, clots from stroke ... etc among other things.

Investigation of Acoustic Wavelength Effects on Silicon Compatible Al Doped ZnO SAW Resonator

This paper addresses the investigation of acoustic wavelength effects on silicon compatible SAW resonator based on Al doped ZnO thin film. Three different resonators at acoustic wavelength of 3.2, 3.6 and 4.8 µm were simulated using COMSOL Multiphysics. The device is fabricated using post CMOS approach namely deposition of 3.78 µm thickness of Al doped Zinc Oxide (AZO) thin film, photolithography and wet etching. S-parameter measurements shows the series resonance frequency occurred at 1.156 GHz, 1.098 GHz and 0.966 GHz for three different wavelength respectively. The influence of acoustic wavelength on resonance frequency, acoustic wave velocity and electromechanical coupling coefficient were discussed. The best transmission characteristic was observed by Resonator 3 due to highest coupling coefficient of 0.069% and lowest insertion loss of 40.5 dB. The range of extracted SAW velocity is between 4161 m/s to 4497 m/s. Hence, the measurement results are consistent with finite element simulation results with deviation less than 5% in terms of resonance frequency and acoustic wave velocity.

Analysis of inductive powering harvesting circuit

The use of implanted devices for biomedical applications is on the rise. As reliability and longevity of the power source is an issue of concern so research is underway for using other means of energy sources such as solar, vibrations and inductive coupling, The inductive coupling providing a non-invasive means of energy source, and is hence considered the most reliable contender. In this case the primary coil is wound on an external mount while the secondary (few turns) is embedded on implanted bed. A theoretical and simulation of inductive coupling is done using MATLAB© exploring its frequency response.

Fabrication techniques and performance of piezoelectric energy harvesters

Energy harvesting devices which convert ambient energy to electrical energy has attracted a lot of attention in commercial sectors. Due to the environmental consciousness, energy harvesting devices or so called micro generators promise a cleaner environment by avoiding the usage of batteries. Piezoelectric energy harvesters are the most promising solution because they can efficiently convert mechanical strain to electrical charge without any additional power. This paper presents a comparative study of previous works on the design and fabrication techniques of piezoelectric energy harvester microgenerators. This lead to an understanding of the several crucial factors affecting the perfomance of the piezoelectric micro generators.