Separation and metrology of nanoparticles by nanofluidic size exclusion.

A nanofluidic technology for the on-chip size separation and metrology of nanoparticles is demonstrated. A nanofluidic channel was engineered with a depth profile approximated by a staircase function. Numerous stepped reductions in channel depth were used to separate a bimodal mixture of nanoparticles by nanofluidic size exclusion. Epifluorescence microscopy was used to map the size exclusion positions of individual nanoparticles to corresponding channel depths, enabling measurement of the nanoparticle size distributions and validation of the size separation mechanism.