Ion transport through a T-intersection of nanofluidic channels

Ion transport through a T-intersection of two silica nanochannels (a main channel, 5-mum long and 30-nm wide, and a subchannel, 5-microm long and 15-nm wide) with a surface charge distribution was investigated based on continuum dynamics calculations. The surface charge within 250 nm of the intersection in the main channel and the entire subchannel was positive and that in the main channel outside this intersection region was negative. This nanofluidic system is analogous to a p-n-p transistor. The calculation results revealed that, by adjusting the electric potentials at the ends of the nanochannels, the ionic current could be (1) cut off, (2) regulated in the main channel, (3) diverged into the main and subchannels, (4) turned from the main channel to the subchannel, and (5) merged into the subchannel. A series connection of this nanofluidic system can therefore be used in biotechnological applications for electrophoretic separation and for sorting of ions and biomolecules.