Optofluidic devices for on-chip optical filtering, sensing, and manipulation

Optofluidics---the marriage of optical methods and microfluidic environments---has seen increasing interest in recent years. Optofluidic devices have emerged that allow for manipulation of optical device properties using fluids or interrogating fluids with optical methods including the arena of biosensors. One approach to biosensor technology has utilized liquid-core antiresonant reflecting optical waveguides (ARROWs). Liquid-core ARROWs have provided devices with inexpensive standard silicon microfabrication, compatibility with semiconductor technology, optical component integration capabilities, small chip dimensions, minute excitation volumes, and high optical intensities in the fluid environment of interest. Optofluidic ARROWs have demonstrated single-molecule fluorescence detection sensitivity and single-particle fluorescence detection of liposomes and viruses. The goal of this thesis was to improve the existing optofluidic ARROW platform and expand its scope by using liquid-core waveguides for particle manipulation and exploiting the device's unique spectroscopic design freedoms on the integrated chip.;For the first time, the interconnected solid- and liquid-core ARROWs enabled a fully-planar optofluidic chemical sensing platform with 30nM sensitivity. A novel waveguide loss-based approach demonstrated unique on-chip optical particle manipulation and trapping platform capabilities for particles such as E. coli. Unlike typical optical traps that confine particles to a region of microns, this platform allowed for particle trapping at any point over distances of 4 mm on an integrated chip and opens up further design opportunities. A novel method to characterize hollow-core waveguides exploiting optically-induced particle transport was demonstrated to inexpensively, nondestructively, and easily measure the waveguide loss and mode profiles. A tapered waveguide design led to a device with fundamental-mode coupling of 95%, a six-fold increase in optical particle manipulation confinement, and doubled fluorescent particle detection efficiency. Device solid-liquid interfacial loss was improved by a hollow-core design to transmissions of 79+/-19% (2.3-fold improvement) and a total optical throughput increase of 1.7 times. A method to fabricate solid-core ARROW rejection filters on an optofluidic chip was demonstrated and showed a notch filter function with ∼23dB rejection and 11nm bandwidth. An optofluidic filter designed for Forster resonant energy transfer (FRET) was demonstrated by detecting the FRET signal of Cy3 and Cy5 labeled oliogonucleotides. The filter response showed a pump light rejection extinction of up to 35dB which was applied to increase the detected signal-to-noise ratio by a factor of 8.6 for fluorescent nanoparticles. An optofluidically tunable filter was demonstrated with a >40nm tuning range with a 30dB extinction. Therefore, this thesis describes numerous advancements of optofluidic chip design and capabilities with a large range of applications.