Anthony Demond Watkins

US Patent:

7278324, Oct 9, 2007

Filed:

Jun 15, 2005

Appl. No.:

11/155923

Inventors:

Jan M. Smits - Monument CO, US
Marlen T. Kite - Hayes VA, US
Thomas C. Moore - Poquoson VA, US
Russell A. Wincheski - Williamsburg VA, US
JoAnne L. Ingram - Norfolk VA, US
Anthony N. Watkins - Hampton VA, US
Phillip A. Williams - Suffolk VA, US

Assignee:

United States of America as represented by the Administrator of the National Aeronautics and Space Administration - Washington DC

International Classification:

G01N 19/08

US Classification:

73799, 73774, 73762, 73763, 73788, 977972

Abstract:

A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.