A FLUID MECHANICS APPROACH TO UNDERSTANDING FIBRILLAR STRUCTURAL ORGANIZATION IN 2D AND 3DdissertationsSalazar Coariti, Adriana CarolacreatorToussaint, KimaniAdvisorZenit, RobertoReaderMathiowitz, EdithReaderMorgan, JeffreyReaderBrown University. Biology and Medicine: Biomedical Engineeringsponsor2025, None p.born digitalThesis (Ph. D.)--Brown University, 2025thesesThe structural organization of fibrillar networks plays a central role in determining the mechanical and functional properties of biological tissues. Despite its importance, quantitatively characterizing fiber alignment and organization in two and three dimensions remains challenging. In this dissertation, I present a fluid mechanics–inspired framework for studying fibrillar organization, integrating principles of vector field analysis with advanced optical imaging. Using Fourier transform–second harmonic generation (FT-SHG) microscopy, I acquired high-resolution images of collagen fiber networks and developed a novel method. Fluid-Inspired Fiber Analysis (FIFA), to extract orientation distributions, coherence, and three-dimensional structural descriptors. By drawing analogies to gradient, divergence, and curl operators from fluid mechanics, the approach enables a unified description of local and global organization across multiple length scales. The method was validated on synthetic and biological samples, demonstrating robust performance in capturing alignment transitions, hierarchical features, and spatial heterogeneity. Applications include the quantitative assessment of collagen remodeling in engineered matrices and biological tissues. Together, these results establish a new framework for understanding fibrillar microstructure that bridges fluid mechanics concepts with optical bioimaging, offering quantitative tools for mechanobiology, tissue engineering, and disease diagnostics.Fluid mechanicsMicrostructureFibersSecond harmonic generationcollagen IEnglishRPB20251201