The combination of electronic and mechanical properties of carbon nanotubes (CNTs) has led to wide-ranging investigation of their potential in future electronics and computing, sensors, electrodes, and composites. A method and system for fabricating an array of two or more CNT structures on a coated substrate surface was developed.
A single electrode is coated for a selected voltage application and time interval. The CNT structures are grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.
The technology provides separate procedures for generating and aligning growth of an array of single-wall CNTs (SWCNTs), an array of multi-wall CNTs (MWCNTs), and/or an array of carbon nanofibers (CNFs), with a CNT or CNF length that depends upon the structure involved — generally in the range of 1 to 100 mm.
In one embodiment, an array of SWCNTs is grown by providing a substrate, coated on a first substrate surface with an optional first thickness of a metal underlayer, and coated with a second thickness of one or more active catalysts. An electrode, having an associated voltage magnitude in a range of 0.1 to 100 V or higher, is connected to the substrate first surface or to a substrate second surface for a time interval of selected length in the range of 1 to 100 s, or higher.
The electrode is then removed or disconnected, or it can be allowed to remain connected. A selected heated hydrocarbon gas intermediate species is passed over the coated substrate to successively strip the H atoms and deposit the carbon particles on the catalyst. Connection of the electrode, even for a time interval as short as a few seconds, will result in CNTs or CNFs that are oriented in substantially the same direction, roughly perpendicular to the coated substrate surface, having CNT lengths in a range of 1 to 1,000 mm.
CNT orientation occurs whether the electrode remains connected to the substrate or is disconnected from the substrate.
This work was done by Lance D. Delzeit of Ames Research Center. NASA invites companies to inquire about partnering opportunities and licensing this patented technology. Contact the Ames Technology Partnerships Office at 1-855-627-2249 or ARCTechTransfer@ mail.nasa.gov. Refer to ARC-15404-1.
