Pembangunan sensor asid borik menggunakan sifat resonans plasmon permukaan setempat nanoplat emas

Resonans Plasmon Permukaan Setempat (LSPR) adalah satu fenomena optik hasil interaksi elektron bebas dengan gelombang elektromagnet cahaya pada permukaan nonozarah logam. Sifat LSPR nanozarah logam yang sangat sensitif kepada sifat dielektrik medium persekitaran menyebabkan fenomena ini digunakan secara meluas dalam pembuatan sensor. Tesis ini melaporkan kajian mengenai pembangunan suatu sistem sensor optik bagi mengesan kehadiran asid borik menggunakan LSPR nanoplat emas. Bahan penderia nanohablur emas telah ditumbuhkan di atas substrat kuartza menggunakan kaedah pertumbuhan berantara pembenihan dengan penekanan khusus untuk menghasilkan nanohablur emas berbentuk nanoplat. Menerusi variasi parameter penyediaan yang dilakukan, kaedah pertumbuhan berantara pembenihan ini berjaya menumbuhkan nanohablur emas dengan kepadatan hasil pertumbuhan yang optimum 93.5 ± 14.1 % dari luas permukaan keseluruhan dengan 63.5 % daripadanya adalah nanohablur yang berbentuk nanoplat. Sampel ini disediakan dengan merendam substrat dalam larutan poli-L-lisina (PLL) berkepekatan 5 % sebelum proses pembenihan, melakukan dua kali ulangan proses pembenihan dan tempoh masa lima jam proses pertumbuhan. Spektrum serapan optik dari sampel tersebut mempunyai dua puncak resonans, 548 nm dan 660 nm yang masing-masing berpadanan dengan resonans plasmon permukaan melintang (t-SPR) dan resonans plasmon permukaan membujur (l-SPR). Bagi tujuan pengesanan asid borik, satu sistem sensor dibangunkan terdiri dari satu gentian optik dupleks. Lengan pertama gentian optik itu diguna untuk menghantar cahaya dari satu sumber cahaya ke bahan penderia, manakala lengan kedua untuk menghantar cahaya yang dipantulkan oleh bahan penderia kepada spektrofometer optik. Penderiaan ditentukan dengan mengukur perubahan dua puncak resonans bahan penderia nanohablur emas t-SPR dan l-SPR dalam larutan asid borik dengan menggunakan air nyahion sebagai rujukan. Perubahan tersebut adalah anjakan kedudukan puncak dan keamatan puncak resonans. Didapati kepekaan sensor plasmonik nanohablur emas terhadap kehadiran asid borik adalah linear dengan peningkatan kepadatan nanohablur emas. Kepekaan penderiaan juga adalah linear dengan kepekatan asid borik dalam julat 0.01 mM sehingga 100 mM

Fabrication, characterization and optimization of in-house MOSFET transistor using spin on dopant technique

This thesis explains the development and fabrication of first in-house MOSFET device using spin -on dopant technique at KUKUM Microfahrication Cleanroom. The process started with the establishment of process flow, process modules, and process parameters. Four modules were developed. The characteristics prior to the MOSFET device fabrication namely dry and wet oxidation, etching, resist thiclrness, exposure dose optimization, n-type and p-type spin on dopant and diffusion and also metal thiclrness characterization were recorded. The data were analyzed and applied in the fabrication of MOSFET devices. The MOSFET fabrication process llsed blanket-field oxide for isolation, positive resist for lithography process, Boron and Phosphorus for source/drain doping and aluminum for metallization. The whole MOSFET process had fOllT masking process specifically source/drain masking, gate masking, contact masking, and metal masking. The result for each processes are presented in this thesis

Formation of Monolayer Polystyrene Array Template for Gold Nanomesh Structure

In this study, the preparation of monolayer array template was performed using 0.2 µm polystyrene (PS) nanospheres monodisperse micro particle deposited onto Indium Tin Oxide (ITO) coated glass substrate. The template was used to arrange the gold (Au) in nanomesh structure thus, enhance its homogeneity for having better sensitivity and repeatability in the plasmonic sensor application. PS nanosphere template was prepared by diluting 0.2 µm PS liquid with ethanol in the ratio of 1:3 and stirred with 400 rpm for 1 hours at 40 °C. Next, the PS solution was spin coated on ITO substrate at different speed variation starting from 200 rpm to 800 rpm in 3 minutes at room temperature. The template structure was then inspected with Field Emission-Scanning Electron Microscopy (FESEM). It was found that, the PS nanosphere template with 600 rpm speed shows the most orderly arrangement of PS array. Subsequently, the PS array template was used as a mask to deposit gold (Au) and performed via direct current (DC) sputtering method. Finally, the Au nanomesh structure was obtained using the lift ‒ off process of PS nanosphere template

Development of Smart Sajadah system

Solat is the central element of muslim’s worship. It is one of the five pillars of Islamic faith and an obligatory religious duty for every muslim. The purpose to perform solat is for the muslim to communicate with the ALLAH S.W.T. Next, it is also the action for the muslim to show their appreciated to their God for God’s blessing and submission to God. Muslim need to carry out solat five prescribed times in one day without failure. Each prescribed time has different times of rakaah. Rakaah is a sequence of several routine that needs to be completed [1]. The rakaah is started with stand, then ruku and then followed by sudjood and lastly is sit between two sudjood

Development of a twin-head infusion pump for micromixing

Mixing is a crucial process in most of the industrial technology such as the operation of chemicals and fermentation reactors, combustion engines, polymer blends, and pharmaceutical formulations [1]. For handling a smaller volume of liquid, micromixing is a suitable method that can be applied. Micromixing (micromixer) is one of the microfluidic functions for mixing and blending liquids as precursors for biological process such as cell activation, enzyme reaction, and drug delivery system [2, 3]. There are several advantages of applying microfluidic device (micromixer) in the chemical technological processes such as processing accuracy, efficiency, minimum usage of reagents and ease of disposing of devices and fluids [3]. Basically, micromixers are categorised into passive and active micromixers. Passive micromixer consists of no moving parts and free from additional friction. It does not use external forces, fully dependent on molecular diffusion and chaotic advection for mixing process [4]. In contrast to active micromixers, external forces are applicable to active micromixers by implementing moving elements either within the microchannels, a time-variant, or a pressure field [5]. To create the pressure field differences for moving the liquid within the micromixer, an infusion pump is usually applied

Gold nanoplates for a localized surface plasmon resonance-based boric acid sensor

Localized surface plasmon resonance (LSPR) properties of metallic nanostructures, such as gold, are very sensitive to the dielectric environment of the material, which can simply be adjusted by changing its shape and size through modification of the synthesizing process. Thus, these unique properties are very promising, particularly for the detection of various types of chemicals, for example boric acid which is a non-permitted preservative employed in food preparations. For the sensing material, gold (Au) nanoplates with a variety of shapes, i.e., triangular, hexagonal, truncated pentagon and flat rod, were prepared using a seed-mediated growth method. The yield of Au nanoplates was estimated to be ca. 63% over all areas of the sensing material. The nanoplates produced two absorption bands, i.e., the transverse surface plasmon resonance (t-SPR) and the longitudinal surface plasmon resonance (l-SPR) at 545 nm and 710 nm, respectively. In the sensing study, these two bands were used to examine the response of gold nanoplates to the presence of boric acid in an aqueous environment. In a typical process, when the sample is immersed into an aqueous solution containing boric acid, these two bands may change their intensity and peak centers as a result of the interaction between the boric acid and the gold nanoplates. The changes in the intensities and peak positions of t-SPR and l-SPR linearly correlated with the change in the boric acid concentration in the solution

Cost effective mask design in CMOS transistor fabrication for undergraduates program

This paper presents a new innovative way of teaching undergraduate program using low cost masks. In MOSFET fabrication, the cost to produce a complete mask set for pattern transfer process extremely high and not cost effective for undergraduates program. The purpose of these masks is to define certain functional region on a wafer. In this work, low cost masks have been fabricated with a simple technology. An economical solution of masks using transparency films with various channel lengths from 300 µm to 500 µm has been produced. Six layer photolithography masks of MOSFET were designed using AutoCAD drawing tools and then printed using high resolution laser printer on the transparency film. Contact printing method has been utilized to transfer the mask layouts onto a 4-inch silicon wafer using standard photolithography techniques to check the line uniformity. Optical observation using high power microscope shows that the mask layouts were successfully transferred onto photoresist with minimum variation. These masks are used to fabricate an n-well CMOS transistor and then tested using Keithley 2400 source meter with Lab-view measurement software. The cost effective mask design proposed was really practical for teaching microfabrication undergraduates program

Structural and optical properties of gold nanosphericals in variation of growth time using seed mediated growth method

Nanogold is a type of metallic nanostructures and it is very sensitive to the dielectric environment of the materials due to strong dependency of plasmon on shapes and sizes. The unique properties of gold nanostructures can be implemented as sensing material in Localized Surface Plasmon Resonance (LSPR) sensor. This paper reports an experimental study on growth time effect towards structural and optical properties of gold nanosphericals (AuNSs). The gold nanoplates have been grown on a substrate using seed mediated growth method (SMGM). In this study, the growth time was varied from 30 minutes to seven hours. The largest size of AuNSs is ~ 82.67 nm obtained from 7 hours growth time sample. XRD analysis shows a peak of the diffraction angle occurs at the plane (111) in position ~ 38.19º. The optical absorption spectra of all samples show resonance peaks in the range of 530 nm to 560 nm, which are corresponding to the transverse surface plasmon resonance (t-SPR). Thus, in this study, it was found that the growth time affected the growth of the gold nanostructures with optimum growth time of seven hours. Longer growth time resulted in the larger size of AuNSs and therefore, it is not very suitable to be used in LSPR sensing application

Mini Review of Glucose Detection Using Plasmonic Sensor

Glucose is a crucial compound in human life. Glucose has important roles in energy source production and overall brain health. In addition, it can be converted into other compounds essential for the growth, repair, and maintaining tissues throughout the body. Also, glucose becomes an indicator of diabetes, i.e., ill when the body can not produce insulin hormone properly. The poor management of diabetes can affect long-term complications that can significantly impact a person's quality of life and may lead to disability or even premature death if not properly addressed. Thus, it is important to do glucose detection to stay within a healthy range. The common methods patients use are glucose meters and urine testing on the laboratory scale. This method has several areas for improvement, such as being invasive, needing experts, and requiring a long-time detection. Thus, researchers come into various alternative glucose detection such as chromatography, mass spectrometry, electrochemical, and plasmonic sensor. Chromatography for glucose detection is rarely used in recent years because of its complexity. Then, for mass spectrometry, it is also complicated for the result and maintenance. As for electrochemical methods, the disadvantage is that other electroactive components on the sample can be interfered with. Plasmonic sensors that utilize the Localized Surface Plasmon Resonance (LSPR) phenomenon are considered due to their advantage, i.e., non-invasive, real-time monitoring, and highly sensitive to surrounding medium change. Plasmonic sensors usually use components of light absorption, luminescence, fluorescence, Raman scattering, reflectance, and refractive index based on the nanoparticles used as sensing materials. Still, transmission and reflection are popular and widely applied. Furthermore, plasmonic sensors generally consist of instruments such as a light source, fiber optic, chamber to place substrate/analyte, spectrometer/detector, and computer. Besides, plasmonic sensors can produce different analytical characteristics suitable for different cases and tuned for the need because of the various sensing materials used. Hence, plasmonic sensors become a promising alternative method for glucose detection