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201630 https://hdl.handle.net/2286/R.2.N.201630 http://rightsstatements.org/vocab/InC/1.0/ All Rights Reserved 2025 261 pages Doctoral Dissertation Academic theses en Eger, Joshua Robert Blain, Jennifer Arizona State University Partial requirement for: Ph.D., Arizona State University, 2025 Field of study: Bioengineering Fluorescence-based diagnostics, particularly lateral flow immunoassays (LFIAs), are widely used in point-of-care (POC) applications due to their rapid, sensitive, and quantitative capabilities. However, challenges such as variability in calibration standards and inconsistencies in low-cost instrumentation limit their accuracy, highlighting the need for reliable calibration methods. Moreover, existing benchtop fluorometers are often bulky, expensive, and unsuitable for resource-constrained environments, underscoring the demand for cost-effective, versatile, and sensitive fluorescence detection systems. This dissertation addresses these issues through two major innovations: (1) a solid-state photoluminescence calibration standard and (2) a modular optomechanical fluorescence detection system. The calibration standard utilizes a highly photostable phosphor-based film that provides reproducible intensity and spectral calibration for fluorescence measurements. Unlike traditional solution-based standards, it is resistant to photobleaching and evaporation, making it ideal for field applications. In addition, a 3D-printed modular fluorometer is developed, featuring interchangeable optical filter assemblies for multispectral fluorescence detection. This flexible design enables cost-effective customization while avoiding the need for complex optical components like lenses or dichroic mirrors. The system also incorporates low-cost color gel filters, which help reduce background interference and improve sensitivity. Further contributions include the development of a colorimetric detection platform and the analysis of nitrocellulose-based calibration standards. The former demonstrates a low-cost, open-source platform for detecting antibodies against HPV16, while the latter assesses the viability of nitrocellulose as a substrate for solid-state calibration standards in POC fluorometers. These advancements not only enhance the reliability of fluorescence-based diagnostic tools but also improve their accessibility in resource-limited settings. This dissertation presents the design, characterization, and validation of these technologies, illustrating their potential to improve POC diagnostics and expand fluorescence measurement capabilities across a wide range of applications. Optics Engineering Approaches to Calibration Standard and Optomechanical Design for Point-of-Care Fluorescence Instrumentation