a process for preparing a patterned layer of aligned carbon nanotubes on a substrate including : applying a pattern of polymeric material to the surface of a substrate capable of supporting nanotube growth using a soft - lithographic technique ; subjecting said polymeric material to carbonization to form a patterned layer of carbonized polymer on the surface of the substrate ; synthesising a layer of aligned carbon nanotubes on regions of said substrate to which carbonized polymer is not attached to provide a patterned layer of aligned carbon nanotubes on said substrate .