Microfluidic Size Exclusion Chromatography (μSEC) for Extracellular Vesicles and Plasma Protein Separation

Extracellular vesicles (EVs) are recognized as next generation diagnostic biomarkers due to their disease‐specific biomolecular cargoes and importance in cell–cell communications. A major bottleneck in EV sample preparation is the inefficient and laborious isolation of nanoscale EVs (≈50–200 nm) from endogenous proteins in biological samples. Herein, a unique microfluidic platform is reported for EV‐protein fractionation based on the principle of size exclusion chromatography (SEC). Using a novel rapid (≈20 min) replica molding technique, a fritless microfluidic SEC device (μSEC) is fabricated using thiol‐ene polymer (UV glue NOA81, Young's modulus ≈1 GPa) for high pressure (up to 6 bar) sample processing. Controlled on‐chip nanoliter sample plug injection (600 nL) using a modified T‐junction injector is first demonstrated with rapid flow switching response time (