A nanoscale “monorail” that can creep along a nanotube track has shifted its first load, hauling a gold nugget a distance of 0.5 micrometers.

The central tube is one micrometer long and acts as a rail for the second, smaller, 200-nanometer nanotube. The outer “monorail carriage” is driven by applying current to the inner rail, and can move in both directions along the rail; it can also rotate around it.

The device could be a useful addition to microscopic construction toolkits that researchers hope will advance computing and other fields.