Shazlina Johari
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Preferred name
Shazlina Johari
Official Name
Shazlina, Johari
Alternative Name
Johari, S.
S., Johari
Main Affiliation
Scopus Author ID
53163664100
Researcher ID
GAA-3219-2022

Research Output

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A wearable 3D printed microfluidic device for sweat-sensing application

2024-12 , Nur Fatin Adini Ibrahim , Anas Mohd Noor , Norhayati Sabani , Shazlina Johari

This study focuses on developing a wearable microfluidic device (WMD) using stereolithography (SLA) 3D printing for sweat collection. The use of the SLA technique, particularly in achieving rapid fabrication, printing smooth surfaces, and creation of channels with dimensions below 1 mm. However, it is quite challenging to integrate the SLA 3D printed WMD with a sensor for real-time sweat analysis using a traditional bonding method. In addition, an SLA conventional resin is non-water-washable and is made from a polymer material that tends to cause a hydrophobic effect on the microchannel surface. In this work, a reversible bonding method through mechanical clamping was applied to enable easy assembly and disassembly of the WMD integrated with a sensor. A water-washable clear resin was used to provide a hydrophilic surface, allowing for effective fluid handling. The fluid delivery into the sensor's channel was efficient, taking only 0.06 s after the fluid flowed out at the outlet channel, and it sufficiently covered the entire surface of the sensor. This work also found that closed channels can be created up to 0.6 mm after fine-tuning the minimum achievable using the SLA printer. The dimensions of the printed WMD resulted in a size tolerance difference of 0.05–0.35 mm compared to the 3D model design, indicating a discrepancy of less than 1%. These capabilities promise to advance WMD and enable cutting-edge research in sweat analysis and related fields.

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Simulation and analysis of Piezoresistive microcantilever

2023-12 , Shazlina Johari , Catherine Lim Ee Chen , Bibi Nadia Taib , Mohd Hafiz Ismail , Siti Noorjannah Ibrahim

Currently, most piezoresistive microcantilever sensors are configured with a dual-layer design that includes a piezoresistor integrated onto the upper surface of a microcantilever. The dual-layer design effectively enhances sensitivity and the piezoresistance effect. However, integrating the piezoresistor onto the microcantilever in the fabrication process necessitates additional steps, leading to extended manufacturing times and increased production costs. In this paper, the mechanical behavior of a single-layer piezoresistive microcantilever, namely displacement, stress, and strain, is investigated and analyzed using ANSYS Multiphysics. The contributing factors expected to affect the device's performance are its geometrical dimensions, and the materials used. Regarding the device dimensions, the length, thickness, and width of the cantilever were varied. It was found that the performance of the piezoresistive microcantilever can be improved by increasing the length and decreasing the thickness. The displacement of the microcantilevers increased by about 230%, from 75.76μm to 250.12μm, when the length was increased from 225μm to 350μm. The applied force ranged from 2uN to 12uN. Similarly, the stress and strain produced on the microcantilevers also increased by about 60.83% and 57.22%, respectively. From the material point of view, the microcantilever made with silicon always had the highest displacement value compared to silicon nitride, silicon dioxide, and polysilicon. This is due to the Young's modulus value, where materials with lower Young's modulus will have higher displacement and stress.

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Sn doped ZnO thin film for formaldehyde detection

2020 , S. Ishak , Shazlina Johari , Muhammad Mahyiddin Ramli

In this work, sol-gel with spin coating technique was applied in order to produce undoped and Sn doped ZnO thin film with different doping concentration of 0.5 at%, 1.0at% and 1.5at%. The starter material used was zinc acetate dehydrate (Zn(CH3COO)22H2O). The thin film was deposited on an interdigitated electrodes (IDE) for 5 hours and annealed at the temperatue of 500°C. The crystallite size of the film decreased when dopant was introduced, as well as the surface roughness of the thin film. XRD was used to identify the crystallinity, crystallographic orientation and phase evaluation of undoped and Sn doped ZnO. From the XRD pattern, it was observed that the peaks and diffraction correspond to the wurtzite-structured of ZnO. Sensing results indicate that the gas sensing response increase from undoped to doped ZnO thin film as a function of operating temperature where the maximum response for formaldehyde detection was at 130°C (∼95%) for doping concentration of 1.5at%. The response time for 0.4ppm of formaldehyde was 17sec followed with 16sec, 12sec and 13 sec for 0.6ppm, 0.8ppm and 1.0ppm respectively.

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Characterization of Excimer Laser Micromachining Parameters to Derive Optimal Performance for the Production of Polydimethylsiloxane (PDMS)-based Microfluidic Devices

2024-01-01 , Shazlina Johari , Ting Z.K. , Mazlee Mazalan , Yufridin Wahab , Anas Mohd Noor , Mohd Fairus Ahmad , Muhammad Mahyiddin Ramli

Laser micromachining has been used as an alternative to producing microfluidics structures and simplifying the conventional soft lithography process. In this paper we characterize the excimer laser micromachining parameters and demonstrate its application by producing several microfluidic structures in polydimethylsiloxane (PDMS). The parameters include the number of laser pulses, laser energy and rectangular variable aperture (RVA) in both x- and y-directions. We found that the laser energy and pulse rate affect the depth of micromachining d channels, while RVA in both x- and y-directions affects the width of the channels. Repetition of laser scan does not change the channel width but significantly changes the channel depth. Proper adjustment for laser energy and pulse rate is required to fabricate a desired channels depth. In order to demonstrate the microfabrication capability of an excimer laser with the optimal operating parameters, several microfluidic structures were micromachining d into PDMS with a KrF excimer laser.

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Biomass Waste Incorporation in La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃-α˗Ba(Ce₀.₆Zr₀.₄)₀.₉Y₀.1O₃-δ composite cathode: effects on microstructural and physical properties

2025 , Ismariza Ismail , Nur Ashafieka Abdullah , Norizah Abd Karim , Shazlina Johari , Muhammad Mahyiddin Ramli

This study explores the incorporation of rice straw as a pore-forming agent in fabricating the Laâ‚€.₆Srâ‚€.â‚„Coâ‚€.â‚‚Feâ‚€.₈O₃-α˗Ba(Ceâ‚€.₆Zrâ‚€.â‚„)â‚€.₉Yâ‚€.1O₃–δ (LSCF-BCZY) composite cathode, focusing on its microstructural and physical properties. Conventional cathode materials often face challenges in balancing porosity and structural stability, with synthetic pore formers posing environmental and consistency concerns. To address these issues, rice straw was introduced into the cathode matrix at varying weight percentages, and the composites were sintered at 1000 Â°C. The addition of rice straw was evaluated using X-ray diffraction, scanning electron microscopy, and densitometry. The results revealed that increasing rice straw content significantly enhanced cathode porosity, rising from 5.53 to 27.74%, with a concomitant reduction in density from 1.33 to 0.93 g/cm3, while maintaining the crystalline stability of the LSCF-BCZY composite. Enhanced porosity suggests improved reactant diffusion to active sites, potentially benefiting the cell's performance in future energy applications. This work highlights the potential of agricultural waste as a sustainable and effective alternative to synthetic pore formers in cathode fabrication.

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A Numerical Study of Collective Cell Migration in a Microchannel Driven by Surface Acoustic Wave (SAW) Device

2023-01-01 , Mazlee Mazalan , Anas Mohd Noor , Yufridin Wahab , Shazlina Johari , Mohd Rosydi Zakaria , Zaman W.S.W.K.

Collective cell migration is involved in a variety of biological contexts, including tissue morphogenesis, wound healing, and cancer invasion. Many studies have revealed that chemical, mechanical, and electrical stimulation all affect cell migration. Although an acoustic stimulus has been shown to influence cell migration in the past, the underlying mechanism is still unknown. A computational model that accounts for acoustic-structure interaction was constructed in this study to simulate the formation of a surface acoustic wave (SAW) field and the application of the acoustic pressure field on collective cell migration. A group of cells within a microchannel device and two ports of interdigitated transducers (IDTs) with different wavelengths were modeled. The stresses within cells were investigated as it was influenced by substrate displacement and pressure acoustic in the cell media generated by the SAW device. As a result, we observed the local stress within cells near the solid-fluid interfaces. For propagating SAW, the shorter wavelength of IDTs (600 μm) attributed to high stress at the cell's top and bottom as compared to the SAW device with the longer wavelength (1000 μm). The standing SAW occurred underneath collective cells. The results of standing SAW on cell stress at the bottom confirm that the SAW device can be useful to regulate the abnormalities cellular activities associated with cell migration.

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Hydrothermal growth of titania nanowires for SAW device sensing area

2017-11-22 , Zakaria M.R. , Sh. Nadzirah S. Ayub , Mohd Hafiz Ismail , Shazlina Johari , Uda Hashim

Synthesis of titania or titanium dioxide (TiO2) is attracted to energy and environmental applications. Here, the growth of nanostructure TiO2 nanowires on Si (100) substrates by using the two-step method. Different seed layers of TiO2 were deposited by spin coating and annealing, followed by the growth of TiO2 nanowires by using the hydrothermal method. The sol-gel technique was used in preparing the TiO2 solution for the thin film deposition purpose. Acetic acid, hydrochloric acid and tris (2-aminoethyl) amine were used as a stabilizer to synthesize three different TiO2 seed layers. The aim of this study was to understand the role of polycrystalline size on thin film towards the diameter of nanowires grown as a sensing area in Surface Acoustic Wave (SAW) Biosensor. The morphology and structure of the thin film and TiO2 nanowires were characterized using X-Ray diffraction (XRD), scanning electron microscope (SEM), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM).

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Production of low temperature synthetic graphite

2023-04 , Anis Syafiqa Rosman , Ranjitha Navalan , Muhammad Mahyiddin Ramli , Norizah Abd Karim , Mohd Fairus Ahmad , Shazlina Johari , Norshamsuri Ali @ Hasim , Nurul Huda Osman

Synthetic graphite is a material consisting of graphitic carbon which has been obtained by graphitizing a non-graphitic carbon. The growth in demand, particularly in customizing properties for certain usage has brought about research on viable alternative, low-cost, and environmentally pleasant synthetic graphite production. Biomass wastes are amongst appealing carbon precursors which have been broadly checked out as replacement carbon for graphite production. This research aimed to synthesize synthetic graphite from oil palm trunks at low temperatures (500 °C, 400 °C and 300 °C) under controlled conditions to determine the physical properties and properties of the graphite obtained. After the heat treatment process, the obtained samples were then characterized by using XRD, SEM and RAMAN characterizations. Based on SEM and RAMAN characterization, it can be seen that graphite that undergoes a 500 °C pyrolysis process shows the best results compare to graphite that undergoes a pyrolysis process at the temperatures of 300 °C and 400 °C. The graphite flakes and the peaks obtained for 500 °C graphite are obviously present. For XRD characterization, the best samples at 500 °C were chosen to be characterized. From the results, the sample shows slight behavior imitating the commercialized graphite. Hence, from the characterizations of the samples, it can be concluded that the best synthetic graphite produced was from the oil palm trunks heated at 500 ° C

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A comprehensive review of the recent developments in wearable Sweat-Sensing Devices

2022-10-01 , Nur Fatin Adini Ibrahim , Norhayati Sabani , Shazlina Johari , Asrulnizam Abd Manaf , Asnida Abdul Wahab , Zulkarnay Zakaria , Anas Mohd Noor

Sweat analysis offers non-invasive real-time on-body measurement for wearable sensors. However, there are still gaps in current developed sweat-sensing devices (SSDs) regarding the concerns of mixing fresh and old sweat and real-time measurement, which are the requirements to ensure accurate the measurement of wearable devices. This review paper discusses these limitations by aiding model designs, features, performance, and the device operation for exploring the SSDs used in different sweat collection tools, focusing on continuous and non-continuous flow sweat analysis. In addition, the paper also comprehensively presents various sweat biomarkers that have been explored by earlier works in order to broaden the use of non-invasive sweat samples in healthcare and related applications. This work also discusses the target analyte’s response mechanism for different sweat compositions, categories of sweat collection devices, and recent advances in SSDs regarding optimal design, functionality, and performance.

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Characterization of Zinc Oxide (ZnO) piezoelectric properties for Surface Acoustic Wave (SAW) device

2017-11-22 , Mohd Rosydi Zakaria , Shazlina Johari , Mohd Hafiz Ismail , Uda Hashim

In fabricating Surface Acoustic Wave (SAW) biosensors device, the substrate is one of important factors that affected to performance device. there are many types of piezoelectric substrate in the markets and the cheapest is zinc Oxide substrate. Zinc Oxide (ZnO) with its unique properties can be used as piezoelectric substrate along with SAW devices for detection of DNA in this research. In this project, ZnO thin film is deposited onto silicon oxide substrate using electron beam evaporation (E-beam) and Sol-Gel technique. Different material structure is used to compare the roughness and best piezoelectric substrate of ZnO thin film. Two different structures of ZnO target which are pellet and granular are used for e-beam deposition and one sol-gel liquid were synthesize and compared. Parameter for thickness of ZnO e-beam deposition is fixed to a 0.1kÅ for both materials structure and sol-gel was coat using spin coat technique. After the process is done, samples are annealed at temperature of 500°C for 2 hours. The structural properties of effect of post annealing using different material structure of ZnO are studied using Atomic Force Microscopic (AFM) for surface morphology and X-ray Diffraction (XRD) for phase structure.

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