1D just means it conducts in one direction. Like it's got tiny wires in it.
It's not particularly unusual; anisotropic conductive adhesive is used in your cellphone to glue the screen on. They tape over the electrical pads, then line up the corresponding LCD pads. The tape allows current to flow vertically between the pads, but for adjacent pads it's insulating.
Neodymium magnets are another example. They're made up of a little honeycomb, and inside the cells of the comb are very long, needles of neodymium a single atom thick. They create a magnetic field in a single direction.