New York University Tandon School of Engineering 1 article published in JoVE Engineering Creating Sub-50 Nm Nanofluidic Junctions in PDMS Microfluidic Chip via Self-Assembly Process of Colloidal Particles Xi Wei1,2, Abeer Syed1, Pan Mao3, Jongyoon Han4, Yong-Ak Song1,2 1Division of Engineering, New York University Abu Dhabi (NYUAD), 2Department of Chemical and Biomolecular Engineering, New York University Tandon School of Engineering, 3Newomics, Inc., 4Department of Electrical Engineering and Computer Science, Department of Biological Engineering, MIT We propose a simple self-assembly technique of silica colloidal nanoparticles to create a nanofluidic junction between two microchannels in polydimethylsiloxane (PDMS). Using this technique, a nanoporous bead membrane with a pore size down to ~45 nm was built inside a microchannel and applied to electrokinetic preconcentration of DNA samples.