semiconductor nanowires offer numerous opportunities for next generation subwavelength optical information processors. As the one dimensional building block element a collection of them can assume different functions in three units of nanoscale photonic circuitry;(i) light generation (active part), (ii) interconnects (passive) and (iii) light detection module. All of these three parts operate on the basis of waveguide principles, although several other issues can affect on the functionality of each individual core. These include coupling, confinement, loss, thermoptics and electrooptics effects, and a number of other material or geometrical concerns. Therefore, this project aims to rigorously investigate and model arbitrary geometric semiconductor nanowire structures fabricated by top-down and bottom-up method, light generation mechanism and perform optical characterization of the nanowires using an integrated near field scanning optical microscope with Raman spectrometer and Laser spectroscopy. All modelling processes are based on commercial software and finite difference time domain algorithm (FDTD) to solve Maxwellââ¬â¢s equations for the desired spatial structure. The semiconductor nanowires of interest are silicon, Silica, zinc oxide, and tantalum pentoxide and heterostructure silicon-germanium. The work is then expanded to more complicated cross sections and functional geometries for various material indices. The results can be then employed as the platform to
- explore the possibility of integrating passive nanowire waveguides with other active photonic and electronic devices in nanoscale for more practical architectures. - invistigate the the applicability of Light modulation techniques in nanowire for computing and communication applications. - couple light efficiently form large scale (micro/macroscopic) into nanostructures for practical application. - Model active nanowire devices in order to provide a clear image of light coupling between light generation and light guiding units.
semiconductor nanowires offer numerous opportunities for next generation subwavelength optical information processors. As the one dimensional building block element a collection of them can assume different functions in three units of nanoscale photonic circuitry;(i) light generation (active part), (ii) interconnects (passive) and (iii) light detection module. All of these three parts operate on the basis of waveguide principles, although several other issues can affect on the functionality of each individual core. These include coupling, confinement, loss, thermoptics and electrooptics effects, and a number of other material or geometrical concerns. Therefore, this project aims to rigorously investigate and model arbitrary geometric semiconductor nanowire structures fabricated by top-down and bottom-up method, light generation mechanism and perform optical characterization of the nanowires using an integrated near field scanning optical microscope with Raman spectrometer and Laser spectroscopy. All modelling processes are based on commercial software and finite difference time domain algorithm (FDTD) to solve Maxwellââ¬â¢s equations for the desired spatial structure. The semiconductor nanowires of interest are silicon, Silica, zinc oxide, and tantalum pentoxide and heterostructure silicon-germanium. The work is then expanded to more complicated cross sections and functional geometries for various material indices. The results can be then employed as the platform to
-explore the possibility of integrating passive nanowire waveguides with other active photonic and electronic devices in nanoscale for more practical architectures. -invistigate the the applicability of Light modulation techniques in nanowire for computing and communication applications. -couple light efficiently form large scale (micro/macroscopic) into nanostructures for practical application. -Model active nanowire devices in order to provide a clear image of light coupling between light generation and light guiding units.
semiconductor nanowires offer numerous opportunities for next generation subwavelength optical information processors. As the one dimensional building block element a collection of them can assume different functions in three units of nanoscale photonic circuitry;(i) light generation (active part), (ii) interconnects (passive) and (iii) light detection module. All of these three parts operate on the basis of waveguide principles, although several other issues can affect on the functionality of each individual core. These include coupling, confinement, loss, thermoptics and electrooptics effects, and a number of other material or geometrical concerns. Therefore, this project aims to rigorously investigate and model arbitrary geometric semiconductor nanowire structures fabricated by top-down and bottom-up method, light generation mechanism and perform optical characterization of the nanowires using an integrated near field scanning optical microscope with Raman spectrometer and Laser spectroscopy. All modelling processes are based on commercial software and finite difference time domain algorithm (FDTD) to solve Maxwellââ¬â¢s equations for the desired spatial structure. The semiconductor nanowires of interest are silicon, Silica, zinc oxide, and tantalum pentoxide and heterostructure silicon-germanium. The work is then expanded to more complicated cross sections and functional geometries for various material indices. The results can be then employed as the platform to
-explore the possibility of integrating passive nanowire waveguides with other active photonic and electronic devices in nanoscale for more practical architectures. -invistigate the the applicability of Light modulation techniques in nanowire for computing and communication applications. -couple light efficiently form large scale (micro/macroscopic) into nanostructures for practical application. -Model active nanowire devices in order to provide a clear image of light coupling between light generation and light guiding units.
The aim of the project is to design, develop and implement an interface based on Sigma-Delta Architecture for Micro-Machined Vibratory Gyroscope. The main idea was to improve the linearity, Dynamic range and Bandwidth. How ever, now the challenge is to reduce the noise effect and improve the accuracy and sensitivity of the interface.
The aim of the project is to design, develope and implement an interface based on Sigma-Delta Architecture for Micro-Machined Vibratory Gyroscope. The main idea was to improve the linearaty, Dynamic range and Bandwidth. How ever, now the challenge is to reduce the noise effect and improve the accuracy and sensitivity of the interface.
Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are much smaller than those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip devices through the phenomena of electro-rotation (ROT) and electro-orientation (EO).
The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong.
Once instances where higher-order force and torque terms become significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.
Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are comparable to those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip device through the phenomena of electro-rotation (ROT) and electro-orientation (EO). The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that there when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong. Once instances where higher-order force and torque terms are significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.
Dielectrophoresis (DEP), a phenomenon through which non-uniform electric field exerts force on a dielectric particle immersed in a dielectric medium, is one of the most widely-used techniques for manipulating and characterising biological particles in a lab-on-a-chip device. Inaccurate calculation of the DEP force would lead to incorrect modelling of the device or false determination of particle properties. Most, if not all, models in current literature are based on the so-called "dipolar approximation" for making calculation of the DEP force. This approximation accounts only for the first-order force term and ignores all higher-order terms. Theory predicts this approximation to work well only as long as particle dimensions are comparable to those of the electrode geometry through which the electric field is applied. When the field magnitude varies significantly across the dimensions of the particle, which is a very likely occurrence as electrode geometries shrink in dimensions towards micro-electrode geometries, higher-order force terms are expected to gain increased significance. The same principle applies to torques of electric origin experienced by dielectric particles in lab-on-a-chip device through the phenomena of electro-rotation (ROT) and electro-orientation (EO).
The preliminary aim of this project is to identify situations where higher-order forces are expected to contribute to a considerable extent to the total DEP force. To accomplish this goal, separate calculations have been made, numerically, of the first three terms of the DEP force, based on the "effective moment method", and of the total DEP force, based on an integration of the Maxwell stress tensor, for particles of different shapes and dimensions subjected to electric fields of varied extents of non-uniformity. Through a comparison of the two sets of results it has been verified that there when particle dimensions, be the particles spherical or not, become comparable to a length scale of field non-uniformity, higher-order force terms become increasingly significant such that in some cases they exceed the first-order force term thereby proving the dipolar approximation wrong.
Once instances where higher-order force and torque terms are significant are discovered, the ultimate goal of this project comes into play: to realize an application where higher-order forces and/or torques could dictate particle behaviour in a way that cannot be achieved using a force/torque whose higher-order terms are negligible. One goal in mind is to achieve particle stabilisation through the exertion of higher-order electro-orientational (EO) torques.
My main research area in interest on RMST project is ââ¬ËMicro-fluidic and Lab on a chip Technologyââ¬â¢. I am concentrating on the research for the development of technologies involves fabrication of micro-structure (micro-electrodes) and micro-fluidic polymeric devices. In addition, I am also concentrating on technologies for hot embossing process (HE) on polymers (e.g. COC, COP, PMMA etc) for creating micro-fluid structure and aligned bonding techniques to seal micro-devices.High aspect ratio silicon (Si) mould master is fabricated with micro-fluidic structure using deep reactive ion etched technique (DRIE) to create Ni master using electro-form technique to emboss microfluidic structure on polemers.
Figure 1 shows a Si mould master with micro-fluidic structure. This mould is used for Ni electro-plating. Figure 2 shows a embossed micro-fluidic channel on zeonox 690R COC (Tg 136ðC )using Ni stamp.
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