This study established the thermodynamic stability of amyloid fibrils as a measurable, discriminating property of amyloid polymorphism. Working mainly with α-synuclein, the authors combined chemical (urea) depolymerization with a microfluidic "transient incomplete separation" approach, in which species of different size are partially separated by differential diffusivity in a laminar-flow capillary. On the Fida 1 instrument, Flow Induced Dispersion Analysis (FIDA) and the underlying Taylor Dispersion Analysis measured diffusion coefficients and hydrodynamic radii of monomers and fibrils and resolved the equilibrium concentrations of free monomer versus fibril, from which the free energy of fibril stability was derived — quantifying stability differences between polymorphs. It is an example of using FIDA/TDA to quantify species in solution to derive thermodynamic measurements.