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Papers by Kirat Singh

Research paper thumbnail of Resonant grating sensors using frustrated total-internal reflection

Sensors and Actuators B: …, 1998

Research paper thumbnail of Internally-referenced resonant mirror for chemical and biochemical sensing

Research paper thumbnail of Anti-Resonant Reflecting Optical Waveguides (ARROWS) as Optimal Optical Detectors for μTAS Applications

Micro Total Analysis …, 1998

Research paper thumbnail of Asymmetric anti-resonant reflecting optical waveguides (arrow) as chemical sensors

Analyst, 2002

Anti-resonant reflecting optical waveguides (ARROW) are described which trap light in a low index... more Anti-resonant reflecting optical waveguides (ARROW) are described which trap light in a low index layer between a lower, high-index confining layer and an upper total internal reflection boundary. In this configuration, most of the light (greater than 80%) travels in the low index porous polymer layer, the refractive index of which is monitored by examining the angle at which light is coupled out of the waveguide. It is shown that asymmetric ARROW sensors can be constructed using conventional chemical vapour deposition and spin-coating techniques and their sensitivity is as predicted by theoretical modelling.

Research paper thumbnail of Measurements of light scattering in an integrated microfluidic waveguide cytometer

Journal of …, 2008

An integrated microfluidic planar optical waveguide system for measuring light scattered from a s... more An integrated microfluidic planar optical waveguide system for measuring light scattered from a single scatterer is described. This system is used to obtain 2D side-scatter patterns from single polystyrene microbeads in a fluidic flow. Vertical fringes in the 2D scatter patterns are used to infer the location of the 90-deg scatter (polar angle). The 2D scatter patterns are shown to be symmetrical about the azimuth angle at 90 deg. Wide-angle comparisons between the experimental scatter patterns and Mie theory simulations are shown to be in good agreement. A method based on the Fourier transform analysis of the experimental and Mie simulation scatter patterns is developed for size differentiation.

Research paper thumbnail of Internally-referenced Resonant Mirror devices for dispersion compensation in chemical sensing and biosensing applications

Sensors and Actuators A …, 2002

Research paper thumbnail of A miniaturized wide-angle 2D cytometer

Cytometry Part …, 2006

Background:We present an optical waveguide based cytometer that is capable of simultaneously coll... more Background:We present an optical waveguide based cytometer that is capable of simultaneously collecting the light scattered by cells over a wide range of solid angles. Such comprehensive scattering data are a prerequisite for the microstructural characterization of cells.We present an optical waveguide based cytometer that is capable of simultaneously collecting the light scattered by cells over a wide range of solid angles. Such comprehensive scattering data are a prerequisite for the microstructural characterization of cells.Methods:We use latex beads as cell mimics, and demonstrate the ability of this new cytometer to collect back-scattered light in two dimensions (2D). This cytometer is based on a liquid-core optical waveguide, excited by prism coupling, that also serves as the microfluidic channel. In principle, our use of a hemispherical lens allows the collection of scattered light from 0 to 180° in 2D.We use latex beads as cell mimics, and demonstrate the ability of this new cytometer to collect back-scattered light in two dimensions (2D). This cytometer is based on a liquid-core optical waveguide, excited by prism coupling, that also serves as the microfluidic channel. In principle, our use of a hemispherical lens allows the collection of scattered light from 0 to 180° in 2D.Results:The experimentally observed positions of the intensity peaks of the back-scattered light agree well with theoretical prediction of scattering from both 4.0- and 9.6-μm diameter latex beads. The position of the bead, relative to the axes of the hemispherical lens and the microchannel, strongly affects the scattering pattern. We discuss a computational method for determining these offsets.The experimentally observed positions of the intensity peaks of the back-scattered light agree well with theoretical prediction of scattering from both 4.0- and 9.6-μm diameter latex beads. The position of the bead, relative to the axes of the hemispherical lens and the microchannel, strongly affects the scattering pattern. We discuss a computational method for determining these offsets.Conclusions:We show that wide-angle 2D light scattering patterns of cell-sized latex beads can be observed in a microfluidic-based optical cytometer that uses leaky waveguide mode excitation. This chip-based system is compatible with emerging chip-based technologies. © 2005 Wiley-Liss, Inc.We show that wide-angle 2D light scattering patterns of cell-sized latex beads can be observed in a microfluidic-based optical cytometer that uses leaky waveguide mode excitation. This chip-based system is compatible with emerging chip-based technologies. © 2005 Wiley-Liss, Inc.

Research paper thumbnail of Determination of leaky modes in planar multilayer waveguides

Photonics Technology Letters, IEEE, 2002

Research paper thumbnail of Development of a microfluidic device for fluorescence activated cell sorting

Journal of …, 2002

This paper describes the development towards a miniaturized analytical system that can perform th... more This paper describes the development towards a miniaturized analytical system that can perform the major key functions of a flow cytometer. The development aims at diagnostic applications for cell counting and sorting with the ultimate goal of a low-cost portable instrument for ...

Research paper thumbnail of Resonant grating sensors using frustrated total-internal reflection

Sensors and Actuators B: …, 1998

Research paper thumbnail of Internally-referenced resonant mirror for chemical and biochemical sensing

Research paper thumbnail of Anti-Resonant Reflecting Optical Waveguides (ARROWS) as Optimal Optical Detectors for μTAS Applications

Micro Total Analysis …, 1998

Research paper thumbnail of Asymmetric anti-resonant reflecting optical waveguides (arrow) as chemical sensors

Analyst, 2002

Anti-resonant reflecting optical waveguides (ARROW) are described which trap light in a low index... more Anti-resonant reflecting optical waveguides (ARROW) are described which trap light in a low index layer between a lower, high-index confining layer and an upper total internal reflection boundary. In this configuration, most of the light (greater than 80%) travels in the low index porous polymer layer, the refractive index of which is monitored by examining the angle at which light is coupled out of the waveguide. It is shown that asymmetric ARROW sensors can be constructed using conventional chemical vapour deposition and spin-coating techniques and their sensitivity is as predicted by theoretical modelling.

Research paper thumbnail of Measurements of light scattering in an integrated microfluidic waveguide cytometer

Journal of …, 2008

An integrated microfluidic planar optical waveguide system for measuring light scattered from a s... more An integrated microfluidic planar optical waveguide system for measuring light scattered from a single scatterer is described. This system is used to obtain 2D side-scatter patterns from single polystyrene microbeads in a fluidic flow. Vertical fringes in the 2D scatter patterns are used to infer the location of the 90-deg scatter (polar angle). The 2D scatter patterns are shown to be symmetrical about the azimuth angle at 90 deg. Wide-angle comparisons between the experimental scatter patterns and Mie theory simulations are shown to be in good agreement. A method based on the Fourier transform analysis of the experimental and Mie simulation scatter patterns is developed for size differentiation.

Research paper thumbnail of Internally-referenced Resonant Mirror devices for dispersion compensation in chemical sensing and biosensing applications

Sensors and Actuators A …, 2002

Research paper thumbnail of A miniaturized wide-angle 2D cytometer

Cytometry Part …, 2006

Background:We present an optical waveguide based cytometer that is capable of simultaneously coll... more Background:We present an optical waveguide based cytometer that is capable of simultaneously collecting the light scattered by cells over a wide range of solid angles. Such comprehensive scattering data are a prerequisite for the microstructural characterization of cells.We present an optical waveguide based cytometer that is capable of simultaneously collecting the light scattered by cells over a wide range of solid angles. Such comprehensive scattering data are a prerequisite for the microstructural characterization of cells.Methods:We use latex beads as cell mimics, and demonstrate the ability of this new cytometer to collect back-scattered light in two dimensions (2D). This cytometer is based on a liquid-core optical waveguide, excited by prism coupling, that also serves as the microfluidic channel. In principle, our use of a hemispherical lens allows the collection of scattered light from 0 to 180° in 2D.We use latex beads as cell mimics, and demonstrate the ability of this new cytometer to collect back-scattered light in two dimensions (2D). This cytometer is based on a liquid-core optical waveguide, excited by prism coupling, that also serves as the microfluidic channel. In principle, our use of a hemispherical lens allows the collection of scattered light from 0 to 180° in 2D.Results:The experimentally observed positions of the intensity peaks of the back-scattered light agree well with theoretical prediction of scattering from both 4.0- and 9.6-μm diameter latex beads. The position of the bead, relative to the axes of the hemispherical lens and the microchannel, strongly affects the scattering pattern. We discuss a computational method for determining these offsets.The experimentally observed positions of the intensity peaks of the back-scattered light agree well with theoretical prediction of scattering from both 4.0- and 9.6-μm diameter latex beads. The position of the bead, relative to the axes of the hemispherical lens and the microchannel, strongly affects the scattering pattern. We discuss a computational method for determining these offsets.Conclusions:We show that wide-angle 2D light scattering patterns of cell-sized latex beads can be observed in a microfluidic-based optical cytometer that uses leaky waveguide mode excitation. This chip-based system is compatible with emerging chip-based technologies. © 2005 Wiley-Liss, Inc.We show that wide-angle 2D light scattering patterns of cell-sized latex beads can be observed in a microfluidic-based optical cytometer that uses leaky waveguide mode excitation. This chip-based system is compatible with emerging chip-based technologies. © 2005 Wiley-Liss, Inc.

Research paper thumbnail of Determination of leaky modes in planar multilayer waveguides

Photonics Technology Letters, IEEE, 2002

Research paper thumbnail of Development of a microfluidic device for fluorescence activated cell sorting

Journal of …, 2002

This paper describes the development towards a miniaturized analytical system that can perform th... more This paper describes the development towards a miniaturized analytical system that can perform the major key functions of a flow cytometer. The development aims at diagnostic applications for cell counting and sorting with the ultimate goal of a low-cost portable instrument for ...

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