This study compared small extracellular vesicles (sEVs) from primary (WM115) and metastatic (WM266-4) melanoma cell lines to identify surface-glycan signatures linked to tumor progression, combining Nanoparticle Tracking Analysis, Western blotting, QCM-D, nanoplasmonic sensing and — for the first time in this context — Flow Induced Dispersion Analysis (FIDA) on a Fida 1 instrument. FIDA quantified Concanavalin A binding to sEV high-mannose glycans, measuring a lower dissociation constant (Kd) and multivalent binding in metastatic sEVs consistent with a denser glycan coat, alongside apparent hydrodynamic radius. It is an example of using FIDA to measure glycan-binding affinity and size of extracellular vesicles in solution.