Papers by Author: Burhanuddin Yeop Majlis

Abstract: The artificial basilar membrane has been developed to mimic the mechanical performance of the basilar membrane in the cochlea. The artificial basilar membrane consists of an array of microbridgeresonators that are mechanically sensitive to the perceived audible frequency range between 20 Hz to 20 kHz. In this work, the finite element (FE) model of the microbridge resonators have been designed in Comsol Multiphysics 4.3 to work close to the audible frequency range. The lumped element (LE) model of the microbridge resonators have been calculated and compared to the simulated FE model. The microbridge resonators array with 0.5 μm thickness, 20 μm width and length varying from 275 μm up to 7700 μm have been designed using two different materials, i.e., platinum (Pt) and aluminium (Al). The microbridge resonators have been found to mimic closely the tonotopicorganisation characteristics of the basilar membrane. From the FE and LE models of the Pt and Almicrobridge resonators, Pt has been found to be a better material than Alfor the artificial basilar membrane design. For the same geometrical dimensions, the Ptmicrobridge resonatorsoperate within the audible frequency range while the Almicrobridge resonatorsoperate approximately 43%-53% above the audible frequency range.

Abstract: This paper reports the study on the shape effect of gold nanoparticles on their plasmonic responses to the vapor samples, such as methanol, ethanol and propanol. In typical process, it was observed that the plasmonic of gold nanoparticles was very sensitive to the presences of the vapor samples by giving the change in the absorption as well as the shift in the SPR peaks position. It was also found that the plasmonic responses to the vapor indicated a significant improved if the gold nanoparticles prepared in the form of nanorods morphology. The plasmonic response of the spherical and nanorods gold nanoparicles to the gasses will be discussed.

Abstract: The limited sensitivity of thinfilm based sensors has motivated the search for sensing structures and materials with greater sensing performance. Although thinfilm based SAW devices have been used as force, pressure, chemical and gas sensors so far. It is limited by the exposed sensing surface of the thinfilm. A feasibility study has been done by implementing the ZnO nanorods (NRs) to enhance the device sensitivity by greatly increase the exposed sensing surface. The implementation of these ZnO NRs as sensing elements is expected to enhance the sensing power due to the large surface to volume ratio. The sensing mechanism in this design is by detecting the minute change of seismic mass for ZnO NRs using surface acoustic wave before and after the attachment of reacting chemical liquid and gas substance.

Abstract: This paper reports the preparation of exceptionally high brightness CdTe quantum dots (QDs) that gives emission in the range of green to red by simply prepared them in a binary mixture of octadecyl phosphonic acid (ODPA) and oleic acid (OA) surfactants. By easy controlling the ratio between the two surfactants in the reaction, the QDs with unique emission, high -brightness and -quantum yield (QY), ca. 63, 87 and 89% for green, yellow and red QDs respectively, can be obtained. Owing to their unique PL and high QY, the CdTe QDs should find an extensive uses in the currently existing applications.

Abstract: Research on microneedles has been increasing rapidly as to overcome the drawbacks of conventional needle which can results in painful during injection, tissue damage and skin infection at the injected site. This paper presents characterization process of wet isotropic etch for solid microneedles array development. This approach utilizes HNA etchant to build the outer shape of solid microneedles. Works has been carried out to investigate the isotropic etching behavior of HNA in different temperature ranging from 20 to 50 degrees, various agitation rate ranging from 0 rpm to 450 rpm and on the various window size ranging from 100 μm to 500 μm. Characterization on those factor, determine the effect of vertical and lateral etch rate variations, surface quality and the geometry obtained. The experimental responses of vertical etch rate, lateral etch rate and high aspect ratio reported. The obtained etching properties will be applied to develop recipes to fabricate outer shape of solid microneedles’ tip.

Abstract: A glucose sensitive actuator for drug delivery system (DDS) consists of silicon boss, micro channel and outlet of the microvalve.The microchannel is essential to carry liquid samples in the system. In this paper, two types of microchannel, rectangular and trapezoidal, were fabricated using anisotropic etching of Deep-RIE and wet chemical etching using KOH solution, respectively. Fabrication were done for micro channels with cross sectional width of 100 -120µm width and length of 2 mm.

Abstract: This paper uses a hybrid simulation approach in CoventorWare design environment which combines finite element analysis and circuit simulation modeling to obtain the optimal performance of piezoresistive microcantilever sensor. A 250 μm x 100 μm x 1 μm SiO2 cantilever integrated with 0.2 μm thick Si piezoresistor were used in this study. A finite element analysis on piezoresistive microcantilever sensor was conducted in CoventorWare Analyzer environment which incorporates MemMech and MemPZR modules. The sensor sensitivity was obtained by measuring resistivity changes in piezoresistive material in response to surface stress changes of microcantilever. The simulation results were later integrated with system-level simulation solver called Architect to enable the optimization of the sensor circuit output. It involves a hybrid approach which uniquely combined FEM analysis and piezoresistive modeling using circuit simulation environment which results in optimal performance of MEMS piezoresistive microcantilever sensor.

Abstract: . In this study, a Piezoelectric Actuated Valveless Micropump (PAVM) has been designed and successfully fabricated using MEMS fabrication processes. A PZT: Pb (ZrTi) Ox (lead titanate zirconate) disc is used to actuate a silicon membrane by applying an alternating electrical field across the actuator. The resultant reciprocating movement of the pump membrane is then converted into pumping effect. Preliminary analysis of the fluidic characteristics of this micropump was performed using CoventorWare Simulator with MEMs-FSI (Fluid Structure Interaction) module to understand the working behaviour of the pump system. The pump is fabricated in a simple micromachining process with two optical masks using a double side polished silicon wafer. The tests carried out on the micropump have produced promising results to be used in the drug delivery system.

Abstract: A novel way to describe the complexity of biological and engineering approaches depending on the number of different base materials is proposed: Either many materials are used (material dominates) or few materials (form dominates) or just one material (structure dominates). The complexity of the approach (in biology as well as in engineering) increases with decreasing number of base materials. Biomimetics, i.e., technology transfer from biology to engineering, is especially promising in MEMS development because of the material constraints in both fields. The Biomimicry Innovation Method is applied here for the first time to identify naturally nanostructured rigid functional materials, and subsequently analyse their prospect in terms of inspiring MEMS development.

Abstract: This paper presents material properties of a micromachined mesoscopic acoustic speaker for hearing aid applications. The microspeaker has a single turn copper coil on a polyimide membrane, and an NdFeB permanent magnet beneath the membrane. The fields due to the permanent magnet were computed using FEMM. Then, forces based on the fields and on the coil driving current were computed. Finally, IntelliSuite was employed to simulate membrane displacements and stresses. The device, with a polyimide membrane diameter of 2.5 mm and thickness of 2 µm, consumes 3.4 mW to generate a sound pressure level of 108 dB in the human ear.