Extracellular vesicles, or EVs, are tiny membrane-bound particles released by nearly all cells. They carry proteins, RNA, lipids, and other biological cargo that reflect the condition of their parent cells. Because EVs circulate in blood, urine, and other body fluids, scientists see them as promising biomarkers for diagnosing diseases without invasive biopsies. However, traditional laboratory methods such as Western blotting and ELISA analyze EVs in bulk, averaging signals across millions of particles and often missing rare but clinically important subpopulations.