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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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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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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Hydrothermal growth of titania nanowires for SAW device sensing area

2017 , Mohd Rosydi Zakaria , Sh.Nadzirah S. Ayub , Mohd Hafiz Ismail , Shazlina Johari , Uda Hashim

Synthesis of titania or titanium dioxide (TiO 2) is attracted to energy and environmental applications. Here, the growth of nanostructure TiO 2 nanowires on Si (100) substrates by using the two-step method. Different seed layers of TiO 2 were deposited by spin coating and annealing, followed by the growth of TiO 2 nanowires by using the hydrothermal method. The sol-gel technique was used in preparing the TiO 2 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 TiO 2 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 TiO 2 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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We-VoltamoStat: A wearable potentiostat for voltammetry analysis with a smartphone interface

2023-09-01 , Ibrahim N.F.A. , Anas Mohd Noor , Norhayati Sabani , Zulkarnay Zakaria , Wahab A.A. , Manaf A.A. , Shazlina Johari

Wearable technology, such as electronic components integrated into clothing or worn as accessories, is becoming increasingly prevalent in fields like healthcare and biomedical monitoring. These devices allow for continuous monitoring of important biomarkers for medical diagnosis, monitoring of physiological health, and evaluation. However, an open-source wearable potentiostat is a relatively new technology that still faces several design limitations such as short battery lifetime, bulky size, heavy weight, and the requirement for a wire for data transmission, which affects comfortability during long periods of measurement. In this work, an open-source wearable potentiostat device named We-VoltamoStat is developed to allow interested parties to use and modify the device for creating new products, research, and teaching purposes. The proposed device includes improved and added features, such as wireless real-time signal monitoring and data collection. It also has an ultra-low power consumption battery estimated to deliver 15 mA during operating mode for 33 h and 20 min and 5 mA during standby mode for 100 h without recharging. Its convenience for wearable applications, tough design, and compact size of 67x54x38 mm make it suitable for wearable applications. Cost-effectiveness is another advantage, with a price less than 120 USD. Validation performance tests indicate that the device has good accuracy, with an R2 value of 0.99 for linear regression of test accuracy on milli-, micro-, and nano-Ampere detection. In the future, it is recommended to improve the design and add more features to the device, including new applications for wearable potentiostats.

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Simulation of piezoelectric transducer microphone diaphragm based on different materials

2024-06 , Mohd Hafiz Ismail , Wen Jie Koh , Bibi Nadia Taib , Shazlina Johari , Siti Noorjannah Ibrahim

Piezoelectric microphone which utilizes MEMS technology is a type of transducer that converts an input acoustic signal into an output electrical signal. The characteristics of the microphone diaphragm such as the diaphragm design features and the type of piezoelectric materials used will affect the performance of the microphone in terms of sensitivity. It is hard to control the stress of the diaphragm used in the MEMS transducer microphone. A modification of the diaphragm is done in this project to reduce the residual stress of the piezoelectric transducer. In addition, finite element analysis namely structural, modal and harmonic were carried out using Ansys 15.0 to simulate the mechanical and dynamic behaviour of the microphone diaphragm. Two types of diaphragm structure were designed, namely square and circular, while three types of piezoelectric material which are AlN, PZT and ZnO were used as the diaphragm material. The structural analysis findings of the diaphragm subjected to 1 Pa pressure revealed that the circular diaphragm made of AlN material exhibited the highest stress, reaching 43.05 GPa, surpassing the stresses observed in the other two materials. On the contrary, the square diaphragm composed of PZT material demonstrated the lowest stress, with only 1.55 GPa. In terms of resonance frequency, the circular AlN diaphragm achieved the highest resonant frequency, reaching 449.84 kHz, whereas the square PZT diaphragm exhibited the lowest frequency at 200.25 kHz. In general, the circular diaphragm design consistently yielded higher first resonant frequencies compared to the square design.The results show that the circular diaphragm with AlN piezoelectric materials is the ideal diaphragm in the microphone because of the highest stress generated and the first resonant frequency. The stress is related to the sensitivity of a microphone while the high resonant frequency can lead to the better optimization of signal to noise ratio control.

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

2017 , 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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Visible Light-Assisted Charge Extraction in High-Band-Gap SrTiO3 through the Integration of a Triplet Sensitizer-Emitter Thin Film

2024-01-22 , Jie K.V.Y. , Mohd Fairus Ahmad , Mohmad A.R. , Ismail A.M. , Mohd Natashah Norizan , Ramli M.M. , Safizan Shaari , Sulaiman Y. , Shamsul Amir Abdul Rais , Shazlina Johari

A challenge in PV designs, including those with an electron transport layer (ETL), is the presence of ‘parasitic absorbers’. These are layers that absorb light without significantly converting it to electrical current, impacting the total external quantum efficiency (EQE). Strontium titanate (STO), a high-band-gap (3.20 eV) perovskite metal oxide, holds promise as an electron transport layer (ETL) for solar energy harvesting. Despite STO’s potential, it primarily operates in the UV spectrum, not fully utilizing the broader light range, and hence can be the source of parasitic absorbers. In this study, we report a significant enhancement in the EQE of STO through the integration of a triplet sensitizer-emitter (TSE) system, designed to upconvert the visible spectrum into UV light and improve the charge extraction from STO. The TSE system uses carbazolyl dicyanobenzene (4CzIPN) as a sensitizer and p-terphenyl (TP) as an emitter. To investigate the EQE of such a system, we fabricate STO as a PV cell. The revised PV cell architecture (ITO/TiO2/STO/TSE/PEDOT:PSS/Al) is a modification of the conventional configurations (ITO/TiO2/STO/PEDOT:PSS/Al). With the TSE thin film, the modified STO PV cell shows better charge extraction under sunlight compared to the standard STO PV cell, indicating that the upconversion process can enhance the hole conductions from STO to PEDOT:PSS through the TSE system. We noted an EQE increase with intense light of λ > 345 nm in thicker TSE layers and a decrease in the EQE under similar light intensity in thinner TSE layers. The Kelvin probe force measurement (KPFM) data showed that the TSE layer receives holes from STO under illumination. Additionally, time-resolved photoluminescence (TRPL) experiments showed that the TSE/STO thin film is able to produce UV emission after irradiation with lower energy light. Then, the EQE variation in thicker TSE layers under intense irradiation can be attributed to the solid-state upconversion, indicating its thickness-dependent performance. These findings underline the strategies for maximizing the utilization of the solar spectrum in PV applications.

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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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Numerical Simulation of Transdermal Iontophoretic Drug Delivery System

2021-11-25 , Anas Mohd Noor , Zulkarnay Zakaria , Shazlina Johari , Norhayati Sabani , Yufridin Wahab , Manaf A.A.

Transdermal Iontophoretic Drug Delivery System (TIDDS) is a non-invasive method of systemic drug delivery that involves by applying a drug formulation to the skin. The drug penetrates through the stratum corneum, epidermis and dermis layers. Once the drug reaches the dermal layer, it is available for systemic absorption via dermal microcirculation. However, clinical testing of new drug developed for the iontophoretic system is a long and complex process. Recently, most of those major pharmaceutical companies have attempted to consider computer-based bio-simulation strategies as a means of generating the data necessary to help make a better decision. In this work, we used computational modelling to investigate the TIDDS behaviour. Our interest is to study the efficacy of drug diffusion through transdermal delivery, including the thermal effect on the skin. We found that drug will be delivered more efficiently if the electrical potential and the position of electrodes are optimum. We analysed the drug diffusion time of the system using 1,3 and 5 mA DC source. In addition, we also modify the electrode distance from 10 mm to 30 mm long and analysed the effect of delivery time and d effect to the skin thermal. We conclude that, a high electrical current, as instance, a 5 mA DC, delivered the drug faster into the skin but increased the skin temperature because of skin joule heating effect. However, a 30 mm electrodes distance setting decreased the skin temperature significantly than the 10 mm distance with more than 9.7 °C under 5 mA DC and 60 minutes of operation. TIDDS enhanced drug delivery compared to oral consumption and might be suitable used for localizing treatments such as chronic disease. This work provides great potential and is useful to efficiently design of iontophoretic drug delivery system including new drugs delivery applications.

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