Prabakaran A/L Poopalan
Thumbnail Image
Preferred name
Prabakaran A/L Poopalan
Official Name
Prabakaran, A/L Poopalan
Alternative Name
Poopalan, P.
Poopalan, Prabakaran A.L.
Poopalan, Prabakaran
Main Affiliation
Scopus Author ID
7003686974

Research Output

Filters

1
30
Reset filters

Settings
Now showing 1 - 10 of 30
Thumbnail Image
Publication

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.

View
Thumbnail Image
Publication

Nanostructured aluminosilicate from fly ash: Potential approach in waste utilization for industrial and medical applications

2020-04-20 , Ramanathan S. , Subash Chandra Bose Gopinath , Mohd Khairuddin Md Arshad , Prabakaran A/L Poopalan

Fly ash is found as a significant solid waste released from power plants to the atmosphere, but its qualitative and quantitative consumptions for the sustainability are ambiguous. The main issues aroused with the disposal of fly ash are the requirement of a large land area for landfills, cause toxicity and pollution to the soil and groundwater due to the accumulation of heavy metals. Although fly ash is highly recommended for soil amelioration and cement manufacturing, the ultimate usage of the solid waste causes unsatisfactory effect to the ground system and cementitious product, respectively. Apart from direct utilization and disposal of fly ash, it has been well reported in literature for the synthesis of nanosized particles due to its enrichment in silica, kaolin, iron, and alumina. With this regard, aluminosilicates have been acknowledged as one of the prospective nanocomposites synthesized from fly ash. It has proven that naturally occurring geopolymerization of fly ash under alkaline medium results is in the formation of aluminosilicates. As such, synthetic aluminosilicates were highly encouraged to extract from fly ash in large scale due to their excellent physiochemical properties and applications. This overview intends to fill-up the knowledge gap through critically reviewing about fly ash waste for the synthesis of aluminosilicate nanocomposite. The applications of fly ash derived aluminosilicates in industries such as wastewater treatment, agriculture system and as antioxidants are gleaned. Besides the heavy industrial potential, this review encompasses the prospective alternative consumption of fly ash for the production of nanostructured aluminosilicates and their comprehensive assessment in medical applications, especially in drug carrier and drug delivery systems, bone engineering, biosensors, hemodialysis, and intestinal therapeutics.

View
Thumbnail Image
Publication

Analysis of an Electrically Induced Optical Waveguide in a c-axis Barium Titanate Thin Film

2021-12-01 , Arif Mawardi Ismail , Prabakaran A/L Poopalan , Nurjuliana Juhari , Mohd. Azarulsani Md. Azidin

In this paper, we report our analysis of an electrically generated optical waveguide in a c-axis barium titanate (BTO) thin film. The waveguide consists of a BTO thin film which is sandwiched between two electrodes. The thin film forms a waveguide when a voltage difference is applied across the electrodes. It is found that the formed waveguide supports both TE and TM modes, with TM modes more tightly confined within the waveguide than TE modes. The possibility to turn the waveguide on and off simply by turning the electric field on and off may prove useful for optical switching.

View
Thumbnail Image
Publication

Multidimensional (0D-3D) nanostructures for lung cancer biomarker analysis: Comprehensive assessment on current diagnostics

2019-09-15 , Ramanathan S. , Subash Chandra Bose Gopinath , Mohd Khairuddin Md Arshad , Prabakaran A/L Poopalan

The pragmatic outcome of a lung cancer diagnosis is closely interrelated in reducing the number of fatal death caused by the world's top cancerous disease. Regardless of the advancement made in understanding lung tumor, and its multimodal treatment, in general the percentage of survival remain low. Late diagnosis of a cancerous cell in patients is the major hurdle for the above circumstances. In the new era of a lung cancer diagnosis with low cost, portable and non-invasive clinical sampling, nanotechnology is at its inflection point where current researches focus on the implementation of biosensor conjugated nanomaterials for the generation of the ideal sensing. The present review encloses the superiority of nanomaterials from zero to three-dimensional nanostructures in its discrete and nanocomposites nanotopography on sensing lung cancer biomarkers. Recent researches conducted on definitive nanomaterials and nanocomposites at multiple dimension with distinctive physiochemical property were focused to subside the cases associated with lung cancer through the development of novel biosensors. The hurdles encountered in the recent research and future preference with prognostic clinical lung cancer diagnosis using multidimensional nanomaterials and its composites are presented.

View
Thumbnail Image
Publication

Sol-gel synthesis and characterization of Ba1-xGdxTiO3+δ thin films on SiO2/Si substrates using spin-coating technique

2017 , Yen Chin TEH , Ala’eddin A. SAIF , Prabakaran A/L Poopalan

Ba1-xGdxTiO3+δ, at x = 0, 0.05, 0.1, 0.15, 0.2, (BGT) thin films have been fabricated on SiO2/Si substrate using Sol-Gel method. The microstructure and surface morphology of the fabricated films have been investigated using X-ray diffraction (XRD) and atomic force microscopy (AFM). The XRD results show that the fabricated films are crystalline with perovskite structure. There is a shifting of the preferred peak at 31.5o to a higher angle as the doping ratio increases suggesting a distortion lattice exists in the films, which could be due to the substitution of Gd3+ ions into Ba-site. The decreasing of lattice constants confirms the substitution of Gd3+ in BaTiO3 lattice structure. The microstrain and dislocation density are found to be increased with the increase of Gd3+ doping, which attributed to the reduction of lattice volume that due to the ionic size mismatch effect. The AFM results show decreasing trend in both average grain size and roughness parameters. Therefore, the microstructure and surface morphology of BGT samples is strongly dependent on the Gd3+ doping concentration that mainly due to the difference ionic radius substitution.

View
Thumbnail Image
Publication

Aluminosilicate Nanocomposites from Incinerated Chinese Holy Joss Fly Ash: A Potential Nanocarrier for Drug Cargos

2020-02-25 , Ramanathan S. , Subash Chandra Bose Gopinath , Mohd Khairuddin Md Arshad , Prabakaran A/L Poopalan , Anbu P. , Lakshmipriya T.

An incredible amount of joss fly ash is produced from the burning of Chinese holy joss paper; thus, an excellent method of recycling joss fly ash waste to extract aluminosilicate nanocomposites is explored. The present research aims to introduce a novel method to recycle joss fly ash through a simple and straightforward experimental procedure involving acidic and alkaline treatments. The synthesized aluminosilicate nanocomposite was characterized to justify its structural and physiochemical characteristics. A morphological analysis was performed with field-emission transmission electron microscopy, and scanning electron microscopy revealed the size of the aluminosilicate nanocomposite to be ~25 nm, while also confirming a uniformly spherical-shaped nanostructure. The elemental composition was measured by energy dispersive spectroscopy and revealed the Si to Al ratio to be 13.24 to 7.96, showing the high purity of the extracted nanocomposite. The roughness and particle distribution were analyzed using atomic force microscopy and a zeta analysis. X-ray diffraction patterns showed a synthesis of faceted and cubic aluminosilicate crystals in the nanocomposites. The presence of silica and aluminum was further proven by X-ray photoelectron spectroscopy, and the functional groups were recognized through Fourier transform infrared spectroscopy. The thermal capacity of the nanocomposite was examined by a thermogravimetric analysis. In addition, the research suggested the promising application of aluminosilicate nanocomposites as drug carriers. The above was justified by an enzyme-linked apta-sorbent assay, which claimed that the limit of the aptasensing aluminosilicate-conjugated ampicillin was two-fold higher than that in the absence of the nanocomposite. The drug delivery property was further justified through an antibacterial analysis against Escherichia coli (gram-negative) and Bacillus subtilis (gram-positive).

View
Thumbnail Image
Publication

A Point-of-Care immunosensor for human chorionic gonadotropin in clinical urine samples using a cuneated polysilicon nanogap Lab-on-Chip

2015 , S. R. Balakrishnan , Uda Hashim , Subash Chandra Bose Gopinath , Prabakaran A/L Poopalan , H. R. Ramayya , M. Iqbal Omar , R. Haarindraprasad , P. Veeradasan

Human chorionic gonadotropin (hCG), a glycoprotein hormone secreted from the placenta, is a key molecule that indicates pregnancy. Here, we have designed a cost-effective, label-free, in situ point-of-care (POC) immunosensor to estimate hCG using a cuneated 25 nm polysilicon nanogap electrode. A tiny chip with the dimensions of 20.5 × 12.5 mm was fabricated using conventional lithography and size expansion techniques. Furthermore, the sensing surface was functionalized by (3-aminopropyl)triethoxysilane and quantitatively measured the variations in hCG levels from clinically obtained human urine samples. The dielectric properties of the present sensor are shown with a capacitance above 40 nF for samples from pregnant women; it was lower with samples from non-pregnant women. Furthermore, it has been proven that our sensor has a wide linear range of detection, as a sensitivity of 835.88 μA mIU-1 ml-2 cm-2 was attained, and the detection limit was 0.28 mIU/ml (27.78 pg/ml). The dissociation constant Kd of the specific antigen binding to the anti-hCG was calculated as 2.23 ± 0.66 mIU, and the maximum number of binding sites per antigen was Bmax = 22.54 ± 1.46 mIU. The sensing system shown here, with a narrow nanogap, is suitable for high-throughput POC diagnosis, and a single injection can obtain triplicate data or parallel analyses of different targets.

View
Thumbnail Image
Publication

Surface charge transduction enhancement on nano-silica and - Alumina integrated planar electrode for hybrid DNA determination

2021-06-01 , Ramanathan S. , Prabakaran A/L Poopalan , Subash Chandra Bose Gopinath , Mohd Khairuddin Md Arshad , Anbu P. , Lakshmipriya T. , Salimi M.N. , Pandian K.

This study represents the surface charge transduction, an efficient and inexpensive biosensor with modifications by silica-alumina entities and determination of gene sequence hybridization. The sensing surface was made by the planar aluminium interdigitated electrode on silicon substrate. Silica and alumina nanoparticles were engineered on the planar transducer surface and the device sensitivity was investigated. The morphology of silica and alumina particles was characterized through the high-resolution election microscopic analyses and revealed the spherical shaped nanoscale sizes at the range of 45–100 nm. The elemental compositions of silica and alumina nanomaterial were affirmed through energy disperse spectroscopy as prominent peaks of Si, Al and O were observed. Selected area electron diffraction analysis of silica and alumina justified their crystalline and amorphous nature, respectively. XRD analysis revealed the expending cristobalite state of silica crystal and γ-alumina for planar electrode surface enhancement. Fourier transform infrared spectroscopy peak observed at 1094 cm−1 revealed the asymmetric stretching of silica nanoparticles whereas the projecting peak observed at 806 cm−1. Additionally, Al–O stretch and Al–O–Al bending modes were justified with the peaks at 585 and 825 cm−1, respectively. Band gap values of silica and alumina computed were 6.75 eV and 3.20 eV, respectively. The results of DNA probe immobilization and complementation have affirmed that silica modified transducer shows the lowest detection at 10 aM whereas alumina modified transducer displayed insignificant current signal and failed to detect DNA hybridization. To investigate the effect of silica entity and its nanocomposite in detecting DNA hybridization, aluminosilicate nanocomposite was deposited on transducer and attained highly sensitive gene detection. Based on the coefficient regression value, aluminosilicate nanocomposite modified planar transducer has shown good device sensitivity (R2 = 0.96) in contrast to silica and alumina entities.

View
Thumbnail Image
Publication

Gigahertz repetition rate ultrashort laser pulses from coherent external Fabry-Pérot cavity

2020-01-08 , Chan, Tian Seng , Mohamad Halim Abd. Wahid , Prabakaran A/L Poopalan

Transient analysis of ultrashort laser pulses (USP) output from a coherent external Fabry-Pérot cavity (CEFPC) comprising a group delay dispersion (GDD) balanced ultrafast Bragg reflector and a negative dispersion double-chirped mirror for sub-terahertz repetition rate generation is investigated. Analytical results manifest a low multiplication factor (MF) of the CEFPC with value equal to any non-integer, real number greater than unity (NIRNGU) could lead to the amplitude varying, transient timing-jitter, but at very high constant repetition rate (frep-o-Constant) USP output pulse train. For the configuration - (MF) TaeFP = TaUSP-in, where MF is a NZRNGU, the MF is not a factor which usually describes the relationship between the frep-o and frep-i, but rather a factor which determines the correlation of USPs TUSP-in and TeFP. Besides, this mentioned configuration is proven to be more easily to generate a CW, high frep-o USP train (>10GHz) at steady-state, compared to the conventional configuration with MF equal to a non-zero positive integer, which requires a much shorter external cavity length to generate a similar high frep-o USP train.

View
Thumbnail Image
Publication

A study on the refractive index of sol-gel Ba1-x Gdx TiO3 thin films using spectroscopic ellipsometry

2023-01-01 , Saif A.A. , Teh Y.C. , Prabakaran A/L Poopalan

Ba1-x Gdx TiO3 thin films have been fabricated at different Gd3+ ionic concentrations, film thicknesses, and annealing temperatures using the sol-gel method. The refractive index of the Ba1-x Gdx TiO3 films on a silicon substrate is characterized using Spectroscopic Ellipsometry (SE), where the ellipsometry angles Ψ and Δ are fitted very well with the Cauchy dispersion model. The results show that the refractive index at 632.8 nm decreases from 2.18 to 1.892 with the increase of the Gd3+ ratio, while it increases with film thickness and annealing tempera-ture. This trend for refractive index variation is explained based on interatomic spacing and density densification of the films. Using Wemple–Di Domenico (WDD) model shows that the dispersion energy increases with film thickness and annealing temperature and decreases with Gd3+ doping. The relatively high refractive index of the samples supports the possibility of using Ba1-x Gdx TiO3 thin films as AR coating for solar cells.

View