Nanotube fluidic junctions: internanotube attogram mass transport through walls.

We report an experimental and theoretical investigation into mass transport between individual carbon nanotubes (CNTs) via their central cores. These CNT fluidic junctions can serve as basic elements for more complex nanofluidic systems and can also provide a structure for testing theories of fluid flow at the nanoscale. Controlled melting, evaporation, and flowing of copper and tin within and between nanotube shells are investigated experimentally. Cap-to-wall and wall-to-cap mass flow are realized by electric current driven heating, diffusion, and electromigration under low bias voltages between 1.5 and 1.8 V. A comparison shows that the mass loss for the cap-to-wall architecture is much smaller than that for the wall-to-cap junction. A molecular dynamics simulation is presented that provides further insight into the transport mechanism.