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Wong C.L.,Nanyang Technological University | Chen G.C.K.,BC Photonics Technological Co. | Ng B.K.,Nanyang Technological University | Agarwal S.,Nanyang Technological University | And 3 more authors.
Optics Express | Year: 2011

A two-dimensional (2D) spectral SPR sensor based on a polarization control scheme is reported in this paper. The polarization control configuration converts the phase difference between p- and s-polarization occurring at surface plasmon resonance (SPR) into corresponding color responses in spectral SPR images. A sensor resolution of 2.7 × 106 RIU has been demonstrated, which corresponds to more than one order of magnitude resolution improvement (26 times) comparing to existing 2D spectral SPR sensors. Multiplex array detection has also been demonstrated with the spectral SPR imaging sensor. In a 8 × 4 sensor array, 32 samples with different refractive index values were monitored simultaneously. Detection on bovine serum albumin (BSA) antigen-antibody binding further demonstrated the multiplex detection capability of the 2D spectral SPR sensor for bio-molecular interactions. The detection limit is found to be 21ng/ml, which is 36 times better than the detection limit previously reported by phase imaging SPR sensors. In light of the advantages of high sensitivity, 2D multiplex detection and real-time response, the spectral SPR imaging sensor can find promising applications in rapid, high throughput, non-labeling and multiplex detection of protein array for proteomics studies, biomarker screening, disease prognosis, and drug discovery. © 2011 Optical Society of America.


Wong C.L.,Nanyang Technological University | Chen G.C.K.,BC Photonics Technological Company | Ng B.K.,Nanyang Technological University | Agarwal S.,Nanyang Technological University | And 4 more authors.
Optical Engineering | Year: 2011

In this paper, a full-field photothermal imaging technique, which does not require a time consuming scan as used in the conventional photothermal imaging system, is reported. Imaging on gold nanoparticles (70 nm) and a blue polystyrene bead (193 nm) were conducted and the experimental results demonstrate the visualization ability of the photothermal imaging technique on nanotargets that are below the diffraction limit. The photothermal imaging system can be operated in an ambient environment where vacuum is not required. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).


Samani M.K.,Nanyang Technological University | Khosravian N.,Nanyang Technological University | Chen G.C.K.,BC Photonics Technological Company | Shakerzadeh M.,Nanyang Technological University | And 2 more authors.
International Journal of Thermal Sciences | Year: 2012

Thermal conductivity of individual multiwalled carbon nanotubes (MWCNT) is measured using a pulsed photothermal reflectance technique. Intrinsic thermal conductivity of individual MWCNT with a diameter 150 nm and length 2 μm at room temperature is extracted to be 2586 W/mK. Individual MWCNT is surrounded by SiO 2, so parallel resistor model is applied in which SiO 2 supportive is treated as a conducting channel that transports heat in parallel with MWCNT.© 2011 Elsevier Masson SAS. All rights reserved.


Khosravian N.,Nanyang Technological University | Samani M.K.,Nanyang Technological University | Loh G.C.,Nanyang Technological University | Chen G.C.K.,BC Photonics Technological Co. | And 2 more authors.
Journal of Applied Physics | Year: 2013

Non-equilibrium molecular dynamic simulation was employed to investigate the interfacial thermal conductance between diamond and silicon substrate. The interfacial thermal conductance was computed based on Fourier's law. The simulation was done at different temperature ranges and results show that the interfacial thermal conductance between diamond-silicon is proportional to temperature and increases with temperature even above Debye temperature of silicon. Enhancement of thermal boundary conductance with temperature is attributed to inelastic phonon-phonon scattering at the interface. The system size dependence of interfacial thermal conductance was also examined. We found that thermal transport is a function of the system size when the size of system is smaller than the phonon mean free path and increases with the size of structure. We also simulated the effect of interface defect on phonon scattering and subsequently thermal conductance. The results also show that interface defect enhances acoustic phonon scattering which results in reduction of thermal boundary conductance. Our findings provide accurate and valuable information on phonon transport in diamond-silicon structure. © 2013 American Institute of Physics.


Samani M.K.,Nanyang Technological University | Samani M.K.,Singapore Institute of Manufacturing Technology | Samani M.K.,University of Antwerp | Ding X.Z.,Singapore Institute of Manufacturing Technology | And 7 more authors.
Thin Solid Films | Year: 2015

A series of [TiN/TiAlN]n multilayer coatings with different bilayer numbers n = 5, 10, 25, 50, and 100 were deposited on stainless steel substrate AISI 304 by a lateral rotating cathode arc technique in a flowing nitrogen atmosphere. The composition and microstructure of the coatings have been analyzed by using energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), and conventional and high-resolution transmission electron microscopy (HRTEM). XRD analysis shows that the preferential orientation growth along the (111) direction is reduced in the multilayer coatings. TEM analysis reveals that the grain size of the coatings decreases with increasing bilayer number. HRTEM imaging of the multilayer coatings shows a high density misfit dislocation between the TiN and TiAlN layers. The cross-plane thermal conductivity of the coatings was measured by a pulsed photothermal reflectance technique. With increasing bilayer number, the multilayer coatings' thermal conductivity decreases gradually. This reduction of thermal conductivity can be ascribed to increased phonon scattering due to the disruption of columnar structure, reduced preferential orientation, decreased grain size of the coatings and present misfit dislocations at the interfaces. © 2015 Elsevier B.V. All rights reserved.


Xu D.,Nanyang Technological University | Lin Z.,Nanyang Technological University | Vasudevan S.,Nanyang Technological University | Ng B.K.,Nanyang Technological University | And 3 more authors.
Proceedings of the 2012 7th IEEE Conference on Industrial Electronics and Applications, ICIEA 2012 | Year: 2012

This paper focuses on applying Super-Resolution (SR) on Photothermal images of the 4.9μm Red Polystyrene Beads (RPB) obtained from a Photothermal imaging (PTI) system. Since the images acquired from the PTI system are noisy and it can be costly to achieve a higher resolution from the hardware side, it is efficient to do so by SR. In this paper, the experimental procedures are presented and the SR shows significant improvement in the processed images, mainly in terms of resolution, sharpness and contrast. © 2012 IEEE.


Samani M.K.,Nanyang Technological University | Samani M.K.,Singapore Institute of Manufacturing Technology | Ding X.Z.,Singapore Institute of Manufacturing Technology | Amini S.,Nanyang Technological University | And 4 more authors.
Thin Solid Films | Year: 2013

A series of physical vapour deposition titanium aluminum silicon nitride nanocomposite coating with a different (Al + Si)/Ti atomic ratio, with a thickness of around 2.5 μm were deposited on stainless steel substrate by a lateral rotating cathode arc process in a flowing nitrogen atmosphere. The composition and microstructure of the as-deposited coatings were analyzed by energy dispersive X-ray spectroscopy, and X-ray diffraction, and cross-sectional scanning electron microscopy observation. The titanium nitride (TiN) coating shows a clear columnar structure with a predominant (111) preferential orientation. With the incorporation of Al and Si, the crystallite size in the coatings decreased gradually, and the columnar structure and (111) preferred orientation disappeared. Thermal conductivity of the as-deposited coating samples at room temperature was measured by using pulsed photothermal reflectance technique. Thermal conductivity of the pure TiN coating is about 11.9 W/mK. With increasing the (Al + Si)/Ti atomic ratio, the coatings' thermal conductivity decreased monotonously. This reduction of thermal conductivity could be ascribed to the variation of coatings' microstructure, including the decrease of grain size and the resultant increase of grain boundaries, the disruption of columnar structure, and the reduced preferential orientation. © 2013 Elsevier B.V.


Chen G.,BC Photonics Technological Co | Loo J.,Nanyang Technological University | Wijaya M.,Nanyang Technological University | Hoe Y.T.,Nanyang Technological University
Optics InfoBase Conference Papers | Year: 2011

Phase Shifting Interferometer using the Carre and Hariharan algorithms is proposed for quantifying resorption in bone sample. Advantages of the system include being non-contact, 3D profile, less time consuming, and relatively inexpensive. © 2010 Optical Society of America.


Khosravian N.,Nanyang Technological University | Samani M.K.,Nanyang Technological University | Loh G.C.,Nanyang Technological University | Chen G.C.K.,BC Photonics Technological Co. | And 2 more authors.
Computational Materials Science | Year: 2013

Thermal transport in graphene with one type of grain boundary loop was investigated using non-equilibrium molecular dynamics simulation method. The results showed that thermal conductivity is very sensitive to defect concentration. It rapidly decreases in the presence of a defect. This is attributed the phonon defects scattering which shorten the phonon mean free paths leading to the reduction in thermal conductivity. Furthermore, temperature dependency of thermal conductivity of pristine and defected graphene was determined. The results indicated that thermal conductivity of defect-free graphene varies significantly with temperature, while thermal conductivity of graphene with defect remains nearly invariant with the temperature of the system. This implies the possibility of phonon-defect scattering domination over Umklapp phonon-phonon scattering in graphene with defect. © 2013 Published by Elsevier B.V.

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