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This thesis reports the design, fabrication, and operation of silicone based multiplexed electrospray (MES) emitters. After reviewing the feasibility of utilizing electrospray as a scalable thin film deposition technique as well as the advantages and limitations of prior MES emitters, we present a design rationale for MES suitable for highly conductive and corrosive fluids. Then we customized a 1064nm fiber laser micromachining system to precisely and rapidly machine silicone sheet and silicon wafers. Laser energy and path are judicially chosen to create clean and round micro posts that form the external structure of the nozzles. For MES with low flow rate per nozzle, it is of vital importance to evenly distribute the liquid into each nozzle on the entire MES array by controlling the pressure drop inside each fluid flow channel. To this end, we modeled the dimension of microfluidic channels that introduce flow impedance overwhelming surface tension at the nozzle tip. We presented laser microfabrication techniques for fabricating two typical types of microfluidic channels: the through-hole array on conductive silicone sheets and the in-plane microfluidic channel on silicon wafers. Next, we developed a convenient assemble process for the integration of three layers (distributor layer, extractor layer, and collector layer) of the MES emitter. The uniformity of the flow rate among nozzles on MES emitters was investigated by observing the overall spray profiles and measuring the diameter of each jet. The results suggest that the silicone-based MES emitters are feasible for spraying highly conductive and corrosive liquids. The MES emitter developed in this thesis may become a promising tool in the scalable manufacturing of thin film perovskite solar cells. / Master of Science / Liquid sprays have widespread applications such as spray coating, spray drying, spray pyrolysis, and spray cooling. Among various types of sprays, electrohydrodynamic spray (electrospray) has several unique properties such as quasi-monodispersity, tunable droplet size from a few micrometer to nanometers, and compatible with roll-to-roll processing of advanced materials. On the other hand, solution-processed perovskite solar cells have attracted immense research interest recently: within the past seven years, efficiencies of perovskite solar cells have rapidly increased from 3.8% to over 20%. Electrospray is a potential film deposition technique to replace spin coating for continuously fabricating thin-film perovskite solar cells with large areas and virtually no material waste. However, two major challenges exist for electrospraying liquid solutions of perovskite precursors. First, the solution is highly corrosive due to lead (Pb) ions which prevent the use of common metals (i.e. copper, stainless steel, and aluminum). Second, the solution is highly electrical conductive which demands low flow rates (~100nL/min) which make it difficult to multiplex. This thesis reports the design, fabrication, and operation of silicone based multiplexed electrospray (MES) emitters. After reviewing the feasibility of utilizing electrospray as a scalable thin film deposition technique as well as the advantages and limitations of prior MES emitters, we present a design rationale for MES suitable for highly conductive and corrosive fluids. Then we customized a 1064nm fiber laser micromachining system to precisely and rapidly machine silicone sheet and silicon wafers. Laser energy and path are judicially chosen to create clean and round micro posts that form the external structure of the nozzles. For MES with low flow rate per nozzle, it is of vital importance to evenly distribute the liquid into each nozzle on the entire MES array by controlling the pressure drop inside each fluid flow channel. To this end, we modeled the dimension of microfluidic channels that introduce flow impedance overwhelming surface tension at the nozzle tip. We presented v laser microfabrication techniques for fabricating two typical types of microfluidic channels: the through-hole array on conductive silicone sheets and the in-plane microfluidic channel on silicon wafers. Next, we developed a convenient assemble process for the integration of three layers (distributor layer, extractor layer, and collector layer) of the MES emitter. The uniformity of the flow rate among nozzles on MES emitters was investigated by observing the overall spray profiles and measuring the diameter of each jet. The results suggest that the silicone-based MES emitters are feasible for spraying highly conductive and corrosive liquids. The MES emitter developed in this thesis may become a promising tool in scalable manufacturing of thin film perovskite solar cells.

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Optics and photonics enable important technological solutions for critical areas such as health, communications, energy, and manufacturing. Novel nanofabrication techniques, on the other hand, have enabled the realization of ever shirking devices. On-chip photonic micro-resonators, the fabrication of which was made possible in the recent decade thanks to the progress in nanofabrication, provide a sensitive and scalable transduction mechanism that can be used for biochemical sensing applications. The recognition and quantification of biological molecules is of great interest for a wide range of applications from environmental monitoring and hazard detection to early diagnosis of diseases such as cancer and heart failure. A sensitive and scalable biosensor platform based on an optimized array of silicon nitride microring resonators is proposed for multiplexed, rapid, and label-free detection of biomolecules. The miniature dimension of the proposed sensor allows for the realization of handheld detection devices for limited-resource and point-of-care applications. To realize these sensors, the design, fabrication, stabilization, and integration challenges are addressed. Especially, the focus is placed on solving a major problem in using resonancebased integrated photonic sensors (i.e., the insufficiency of wavelength scan accuracy in typical tunable lasers available) by using an interferometric referencing technique for accurate resonance tracking. This technique can improve the limit of detection of the proposed sensor by more than one order of magnitude. The method does not require any temperature control or cooling, and the biosensor platform does not require narrow linewidths necessary for the biosensors based on ultrahigh quality factor resonators, thus enabling low-cost and reliable integration on the biosensor platform.

The significance of this work is that it bridges the powerful multispectral capabilities of single-point confocal microscopy and the speed and gentle imaging characteristics of multipoint confocal. This will be a powerful technique for acquiring full spectral datasets while preventing photobleaching and phototoxicity. This will enable multilabel measurements to be conducted using a single highly sensitive detector and carve a path to the integration of next-generation time-resolved sensors for multispectral multipoint confocal FLIM microscopy at 1Hz imaging rates. The technology will also have a broader significance to the world as it will reduce the complexity and cost of high-speed multispectral confocal microscopy. Using only a single sensor for readout reduces the financial impact of adopting the technology, as traditional multispectral multipoint microscopy ties the number of spectral bands acquired to the number of sensors used. / Capturing cellular dynamics is key to understanding cell behavior, but this task is challenging due to the weak fluorescence signal in live cells. This signal scarcity becomes more pronounced when divided across multiple contrast dimensions, pushing the boundaries of detector sensitivity. This complexity of measurement is essential for revealing the intricate mechanisms governing cellular function. By using spatial, spectral, and fluorescence lifetime imaging contrasts, we can more precisely isolate species and interactions, uncovering previously hidden aspects of cellular behavior. In this work, we present the development of multiple prototypes for multi-dimensional multipoint confocal microscopy, designed to optimize the use of these faint signals and advance the study of cellular dynamics. Our prototype systems, unmatched in speed and spectral resolution, utilize a pinhole array for efficient confocal multiplexing and dense time-resolved detectors, such as a gated optical intensifier, to measure multipoint confocal time-resolved fluorescence spectra. We demonstrate an enhanced optical design using a 32x32 pinhole array and a SPAD array to capture 960x960 pixel images at a frame rate of 4 Hz. Additionally, we present a 10x10 point multispectral FLIM system, representing the first highly multiplexed multispectral confocal FLIM microscope. A novel optical design further improves the acquisition rate by reducing the sensor readout rate requirements from a quadratic sampling problem to a linear sampling problem. This new optical system can capture 22 spectral bands simultaneously across the 450 nm to 650 nm spectral range at a 1Hz frame rate with a final image resolution of 960x1920. These advancements mark a significant step towards realizing a high-speed multipoint multispectral confocal FLIM microscope and lay the groundwork for future improvements and research. / Thesis / Doctor of Philosophy (PhD) / Microscopes are essential tools in biology that allow scientists to visualize microscopic structures and processes within cells. Scientists use glowing molecules called fluorophores to color the different parts of the cell to better understand its function. One function of interest is how proteins interact with each other, as this is one of the core processes of a cell's function in life. To measure these interactions, scientists need to make many measurements over time, but these glowing molecules only work for a short period of time before they fade. Building a microscope that can carefully take these measurements all at once and fast enough to see changes would allow careful measurement and might help explain what is happening within the cell. The different methods of measurement are spatial (3D), spectral (Color), dynamic (time), and a special temporal quantum measurement known as the fluorescence lifetime. Together, these measurements form a multidimensional description of the protein’s behavior. In this thesis, I present the tools developed to address these issues and create a fast, multi-dimensional microscope.

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No description available.

The ability to resolve multiple fluorescent emissions from different biological targets in video rate applications, such as endoscopy and intraoperative imaging, has traditionally been limited by the use of filter-based imaging systems. Hyper and multispectral imaging facilitate the detection of both spatial and spectral information in a single data acquisition, however, instrumentation for spatiospectral data acquisition is typically complex, bulky and expensive. This thesis seeks to overcome these limitations by using recently commercialised compact and robust hyper/multispectral cameras based on spectrally resolved detector arrays. Following sensor calibrations, which devoted particular attention to the angular sensitivity of the sensors, we integrated spectrally resolved detector arrays into a wide-field and an endoscopic imaging platform. This allowed multiplexed reflectance and fluorescence imaging with spectrally resolved detector array technology in vitro, in tissue mimicking phantoms, in an ex vivo oesophageal model and in vivo in a mouse model. A hyperspectral linescan sensor was first integrated in a wide-field near-infrared reflectance based imaging set-up to assess the suitability of spectrally resolved detector arrays for in vivo imaging of exogenous fluorescent contrast agents. Using this fluorescence hyperspectral imaging system, we could accurately resolve the presence and concentration of seven fluorescent dyes in solution. We also demonstrated high spectral unmixing precision, signal linearity with dye concentration, at depth in tissue mimicking phantoms, and delineation of four fluorescent dyes in vivo. After the successful demonstration of multiplexed fluorescence imaging in a wide-field set-up, we proceeded to combine near-infrared multiplexed fluorescence imaging with visible light spectral reflectance imaging in an endoscopic set-up. A multispectral endoscopic imaging system, capable of simultaneous reflectance and fluorescence imaging, was developed around two snapshot spectrally resolved detector arrays. In the process of system integration and characterisation, methods to characterise and predict the imaging performance of spectral endoscopes were developed. With the endoscope we demonstrated simultaneous imaging and spectral unmixing of chemically oxy/deoxygenated blood and three fluorescent dyes in a tissue mimicking phantom, and of two fluorescent dyes in an ex vivo oesophageal porcine model. With further developments, this technology has the potential to become applicable in medical imaging for detection of diseases such as gastrointestinal cancers.

This thesis presents the development and optimization of a high-throughput fluorescence microbead based approach for multiplexed, large scale medical diagnostics of biological fluids. Specifically, different sizes of semiconductor nanocrystals, called quantum dots, are infused into polystyrene microspheres, yielding a set of spectrally unique optical barcodes. The surface of these barcodes are then used for sandwich assays with target molecules and fluorophore-conjugated detection antibodies, changing the optical spectra of beads that have associated with (or captured) biomolecular targets. These assayed microbeads are analyzed at a single bead level in a high-throughput manner using an electrokinetic microfluidic system and laser induced fluorescence. Optical signals collected by solid state photodetectors are then processed using novel signal processing algorithms. This document will discuss developments made in each area of the platform as well as optimization of the platform for improved future performance.

This thesis presents the development and optimization of a high-throughput fluorescence microbead based approach for multiplexed, large scale medical diagnostics of biological fluids. Specifically, different sizes of semiconductor nanocrystals, called quantum dots, are infused into polystyrene microspheres, yielding a set of spectrally unique optical barcodes. The surface of these barcodes are then used for sandwich assays with target molecules and fluorophore-conjugated detection antibodies, changing the optical spectra of beads that have associated with (or captured) biomolecular targets. These assayed microbeads are analyzed at a single bead level in a high-throughput manner using an electrokinetic microfluidic system and laser induced fluorescence. Optical signals collected by solid state photodetectors are then processed using novel signal processing algorithms. This document will discuss developments made in each area of the platform as well as optimization of the platform for improved future performance.