Foo Kai Loong
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Preferred name
Foo Kai Loong
Official Name
Foo, Kai Loong
Alternative Name
Loong, Foo Kai
Kai Loong, Foo
Foo, K. L.
Foo, Kai Loong
Foo, Kai Long
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Scopus Author ID
37012449500
Researcher ID
D-2035-2015

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Low temperature annealed zinc oxide nanostructured thin film-based transducers: Characterization for sensing applications

2015 , R. Haarindraprasad , Uda Hashim , Subash Chandra Bose Gopinath , Muhammad Kashif , P. Veeradasan , S. R. Balakrishnan , Foo Kai Loong , Prabakaran A/L Poopalan

The performance of sensing surfaces highly relies on nanostructures to enhance their sensitivity and specificity. Herein, nanostructured zinc oxide (ZnO) thin films of various thicknesses were coated on glass and p-type silicon substrates using a sol-gel spin-coating technique. The deposited films were characterized for morphological, structural, and optoelectronic properties by high-resolution measurements. X-ray diffraction analyses revealed that the deposited films have a c-axis orientation and display peaks that refer to ZnO, which exhibits a hexagonal structure with a preferable plane orientation (002). The thicknesses of ZnO thin films prepared using 1, 3, 5, and 7 cycles were measured to be 40, 60, 100, and 200 nm, respectively. The increment in grain size of the thin film from 21 to 52 nm was noticed, when its thickness was increased from 40 to 200 nm, whereas the band gap value decreased from 3.282 to 3.268 eV. Band gap value of ZnO thin film with thickness of 200 nm at pH ranging from 2 to 10 reduces from 3.263eV to 3.200 eV. Furthermore, to evaluate the transducing capacity of the ZnO nanostructure, the refractive index, optoelectric constant, and bulk modulus were analyzed and correlated. The highest thickness (200 nm) of ZnO film, embedded with an interdigitated electrode that behaves as a pH-sensing electrode, could sense pH variations in the range of 2-10. It showed a highly sensitive response of 444 μAmM-1cm-2 with a linear regression of R2 =0.9304. The measured sensitivity of the developed device for pH per unit is 3.72μA/pH.

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Fabrication of Integrated Electrode for pH Sensor Application

2021-01-01 , Mohd Akhir F.S. , Foo Kai Loong , Jin T.S. , Uda Hashim , Voon Chun Hong , Azman Abu Hassan M.

Integrated Electrode (IDEs), as a sensor, is a pervasive device in modern electronics and future hopes for producing a highly sensitive and selective sensor. In this work, a simple method of conventional photolithography for the fabrication of interdigitated electrodes is presented in detail. The structural of highly uniform IDEs device was optically characterized using high power microscope (HPM) and scanning electron microscope (SEM). Besides, the fabricated IDEs device was undergone electrical measurement with different pH. The result shows the highest current at 96 nA when the IDEs was tested with pH 10. Overall, our study establishes a correlation between structural and electrical properties of Al IDEs thin films with different pH

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The effect of graphite type on the synthesis of SiC nanomaterials by microwave-assisted synthesis

2020-09-01 , Mat Kahar S. , Voon Chun Hong , Lim B.Y. , Subash Chandra Bose Gopinath , Al-Douri Y. , Mohd Khairuddin Md Arshad , Foo Kai Loong , Nor Azizah Parmin , Ten S.T.

SiC nanomaterial (SiCNM) is known for its excellent properties and has great potential for a wide range of applications. In this article, preparation of SiCNMs from different types of graphite was performed by microwave-assisted synthesis. Different types of graphite which are graphite flake (GF) and expanded graphite (EG) were used to react with silica for the synthesis of SiCNMs in laboratory microwave furnace at 1400 Â°C. It was found that SiC nanowhiskers (SiCNWs) were formed when EG was used, while irregular shaped SiC nanoparticles (SiCNPs) were formed when GF was used. β-SiC appeared as the only phase in the XRD patterns for both SiCNMs formed using GF and EG. SiCNWs and SiCNPs have interplanar spacing of around 0.25 nm which is the axial direction of [111]. The difference of formation mechanism is believed to be the origin of different morphology of SiCNMs synthesized from different types of graphite.

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Comparative mechanical and microstructural properties of high calcium fly ash one-part geopolymers activated with Na2SiO3-anhydrous and NaAlO2

2021-11-01 , Ooi Wan-En , Liew Yun Ming , Heah Cheng Yong , Mohd. Mustafa Al Bakri Abdullah , Li L.Y. , Ho Li Ngee , Foo Kai Loong , Ong Shee-Ween , Ng Hui-Teng , Ng Yong-Sing , Nur Ain Jaya

This paper investigates the effect of varying solid alkali activators on the fresh and hardened properties and microstructural changes of one-part geopolymers (OPGs). Single and binary solid alkali activators were used to activate high calcium fly ash. The alkali activators were either solely sodium metasilicate (Na2SiO3) or a combination of sodium aluminate (NaAlO2) and sodium metasilicate (Na2SiO3). The OPG activated with anhydrous Na2SiO3 achieved an excellent 28-day compressive strength of 83.6 MPa while OPG activated with NaAlO2 and Na2SiO3 attained a compressive strength of 45.1 MPa. The Na2SiO3-activated OPG demonstrated better fluidity than the OPG activated with NaAlO2 and Na2SiO3 due to the thixotropic behaviour caused by the NaAlO2. The Na2SiO3-activated OPG consisted of sodium-calcium aluminium silicate hydrate ((N,C)-A-S-H) gel phase, while the OPG activated with NaAlO2 and Na2SiO3 comprised of the coexistence of sodium aluminium silicate hydrate (N-A-S-H) and calcium aluminium silicate hydrate (C-A-S-H) gel phases. Regardless of the distinctive properties, the OPGs are adequate for building materials applications.

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Improvement synthesis of graphene oxide yield in two steps of intercalation and oxidation of flexible graphite foil by electrochemical exfoliation

2024-04 , M. O. Ariffa , Liu Wei Wen , Foo Kai Loong

Synthesis of high quality and quantity of graphene by cost-effective methods are highly desirable for various application. In electrochemical exfoliation, graphite foil has been used as carbon source for the synthesis of high yield of graphene flakes. Electrochemical exfoliation is one of the faster and cheaper method to synthesize graphene sheets. In this work, five different types of concentration of sulphuric acid were used for electrochemical exfoliation. The electrochemical cell design where graphite foil as anode and copper foil as cathode which were connected to DC power supply of 5V. To examine the morphology scanning electron microscope (SEM) was employed in which the sheet structures with large lateral dimension and thin graphene flakes. Furthermore, X-ray diffraction (XRD) revealed that exfoliated graphene samples showed a significant peak at about 2θ = 26º corresponded to graphite.

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Effect of Alkaline Treatment on Tensile Properties of Low Density Polyethylene/Bean Sprout Skin Composites

2025-06-10 , Tan Soo Jin , Foo Kai Loong , Mohammad Firdaus Abu Hashim

This study the effect of alkaline treatment on the tensile properties of LDPE/BSS and LDPE/BSSNaOH composites at various loadings (5–25 phr). The composites were fabricated through a Z-blade mixer and compressed at the temperature of 160oC. The tensile strength increased with filler loading up to 15 phr but decreased at 20 phr due to filler agglomeration. Alkali treatment enhanced filler-matrix adhesion, resulting in higher tensile strength and Young’s modulus for LDPE/BSSNaOH composites. Elongation at break decreased with filler content, indicating improved stiffness but reduced ductility. The findings highlight the role of filler loading and surface treatment in optimizing mechanical performance, offering insights for developing high-performance, sustainable polymer composites.

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Hydrothermal Growth Zinc Oxide Nanorods for pH Sensor Application

2023-10-01 , Foo Kai Loong , Tan Soo Jin , Heah Cheng Yong , Subash Chandra Bose Gopinath , Liew Yun Ming , Uda Hashim , Voon Chun Hong

The aim of this work is to apply synthesized zinc oxide (ZnO) Nanorods using hydrothermal (HTL) growth technique for pH sensor application. The highly crystallite of ZnO Nanorods was obtained by anneal the growth ZnO Nanorods in furnace at 200 °C for 2 hours. Besides that, XRD analysis shows the produced ZnO Nanorods belonged to the (002) plane. Furthermore, Scanning Electron Microscope (SEM) images confirm that the ZnO Nanorods with hexagonal-faceted structural were successfully produced by HTL growth technique. In addition, Ultraviolet–visible (UV-Vis) spectrophotometer analysis shows that the synthesized ZnO belongs to the wide band gap semiconductor material. The growing ZnO Nanorods were then subjected to electrical measurement with various pH levels. The outcome demonstrates that the current rises as the solution changes from acidic to alkaline. Overall, our study shows a relationship between the electrical as well as the structural characteristics of ZnO Nanorods at various pH levels.

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Towards greener one-part geopolymers through solid sodium activators modification

2022-12-10 , Wan-En O. , Yun-Ming L. , Cheng-Yong H. , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Bin Khalid M.S. , Foo Kai Loong , Shee-Ween O. , Pei Seng T. , Yong Jie H. , Zulkifly K.

This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.

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Towards greener one-part geopolymers through solid sodium activators modification

2022-12-10 , Ooi Wan En , Liew Yun Ming , Heah Cheng Yong , Ho Li Ngee , Mohd. Mustafa Al Bakri Abdullah , Bin Khalid M.S. , Foo Kai Loong , Ong Shee Ween , Pei Seng T. , Hang Yong Jie , Khairunnisa Zulkifly

This paper investigates the influence of various solid activators and their mixing parameters on the physical, mechanical and microstructural characteristics of greener one-part geopolymers (OPG) based on high calcium fly ash. The high calcium fly ash that has rarely been explored was utilised to develop OPG in this study. The anhydrous sodium metasilicate (Na2SiO3) with negative environmental impact propelled the partial replacement of Na2SiO3 with sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). Two sets of high calcium fly ash OPGs were developed: (1) the MH-OPG comprised Na2SiO3 and NaOH; (2) the MC-OPG comprised Na2SiO3 and Na2CO3. The optimal MH-OPG (73 MPa) and MC-OPG (75 MPa) exhibited superior compressive strength, higher than the minimal requirement (>28 MPa) of ASTM C150/C150M-18 for construction binder material. Various solid alkali activators triggered different reaction mechanisms, yielding distinctive reaction products that contributed to strength growth. The sodium calcium aluminosilicate hydrate ((N,C)-A-S-H) gel was developed in MH-OPG, whereas the sodium carbonate hydrate, sodium aluminosilicate hydrate (N-A-S-H) and calcium aluminosilicate hydrate (C-A-S-H) binding phases were developed in the MC-OPG. Although Na2CO3 reduced the water demand, improved the fluidity and setting time, the MC-OPG was more sensitive to the alteration of mixing compositions, suggesting a tougher performance control during field application than the MH-OPG. The total embodied carbon (EC) of MC-OPG was lowered by 15.4% compared to that of MH-OPG. The embodied carbon index (ECI) of MH-OPG and MC-OPG were 81.3% and 84.7% less than that of OPC products. This work suggests that substituting Na2SiO3 with NaOH or Na2CO3 effectively produced a greener construction material without compromising mechanical strength.

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Thermal behaviour and microstructural analysis of Sn-40Pb alloy and Sn-40Pb soldered on electroless nickel/immersion gold

2020 , Ai Ling Teoh , Mohd Arif Anuar Mohd Salleh , Dewi Suriyani Che Halin , Foo Kai Loong

Due to the toxicity of lead solder, the lead-free solder has been developing and improved in order to replace the lead solder. However, the behaviour and properties of lead solder is still better than the lead-free solder, especially in application when soldering on substrate. Hence, a common lead solder, Sn-40Pb is studied in this research by comparing with Sn-40Pb soldering on electroless nickel/immersion gold (ENIG) substrate. The thermal behaviour by differential scanning calorimeter (DSC) and microstructure formation with elemental analysis by scanning electron microscope (SEM) were carried out for Sn-40Pb solder alloy and Sn-40Pb soldered on ENIG substrate in this study. The result showed that the pasty range of Sn-40Pb was lower than Sn-40Pb/ENIG while the undercooling was higher. The diffusion and dissolution of Ni and Cu elements from ENIG substrate into the solder, forming the lead-rich phase with Ni elements and interfacial (Cu,Ni)6Sn5 with Pb elements in Sn-40Pb/ENIG. The diffusion and dissolution of elements from substrate into the solder affects the thermal behaviour and microstructural of solder.

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