The invention provides nanostructures, being arrays of nanosized filamentary material such as carbon nanotubes (CNTs) and other nanomaterials and especially to such materials connected to a substrate such as at least one top electrode and one bottom electrode, and to a method for manufacturing such nanostructures. A device according to the present invention comprises a first and a second layer (11, 13) separated from each other; and nanosized filamentary material (10) grown between said first and said second layer (11, 13). The shape and size of the nanosized filamentary material is determined by the shape and size of the second layer. A corresponding method for growing the nanosized filamentary material is also provided.