CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.
The invention was supported, in whole or in part, by grant No. DE-FG02-00ER45805 from The Department of Energy, grant Nos. DAAD16-00-C-9227 and DAAD16-02-C-0037 from The US Army Natick Soldier Systems Center, grant No. ECS-0103012 from the National Science Foundation, and by grant No. NIH CA-97945-01 from the National Institute of Health. The Government has certain rights in the invention.