Carbon nanotube-based sensor and method for detection of crack growth in a structure
First Claim
1. A method of detecting crack growth experienced by a structure, said method comprising the steps of:
- positioning a plurality of carbon nanotube (CNT)-based sensors into a close grouping on a portion of the structure, each said sensor comprising (i) a substrate adapted to be coupled to the portion of the structure, said substrate being flexible such that strain experienced by the portion of the structure causes relative strain in said substrate, (ii) a plurality of carbon nanotube (CNT)-based conductors operatively positioned on said substrate and arranged side-by-side to one another, said plurality of CNT-based conductors being coated with a gas-impermeable membrane to reduce pressure sensitivity of said plurality of CNT-based conductors, and (iii) at least one pair of spaced-apart electrodes electrically coupled to opposing ends of said plurality of CNT-based conductors with a portion of each of said plurality of CNT-based conductors spanning between each pair of said spaced-apart electrodes comprising a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis;
monitoring electrical properties of said plurality of CNT-based sensors when the portion of the structure is experiencing baseline levels of the parameter of strain to establish a baseline response; and
continually monitoring the electrical properties over time to identify any change in the electrical properties from the baseline response, wherein a change in the electrical properties of said plurality of CNT-based sensors is indicative of crack growth experienced by the portion of the structure.
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Accused Products
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.
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Citations
20 Claims
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1. A method of detecting crack growth experienced by a structure, said method comprising the steps of:
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positioning a plurality of carbon nanotube (CNT)-based sensors into a close grouping on a portion of the structure, each said sensor comprising (i) a substrate adapted to be coupled to the portion of the structure, said substrate being flexible such that strain experienced by the portion of the structure causes relative strain in said substrate, (ii) a plurality of carbon nanotube (CNT)-based conductors operatively positioned on said substrate and arranged side-by-side to one another, said plurality of CNT-based conductors being coated with a gas-impermeable membrane to reduce pressure sensitivity of said plurality of CNT-based conductors, and (iii) at least one pair of spaced-apart electrodes electrically coupled to opposing ends of said plurality of CNT-based conductors with a portion of each of said plurality of CNT-based conductors spanning between each pair of said spaced-apart electrodes comprising a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis;
monitoring electrical properties of said plurality of CNT-based sensors when the portion of the structure is experiencing baseline levels of the parameter of strain to establish a baseline response; and
continually monitoring the electrical properties over time to identify any change in the electrical properties from the baseline response, wherein a change in the electrical properties of said plurality of CNT-based sensors is indicative of crack growth experienced by the portion of the structure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A sensor for detecting crack growth in a structure, comprising:
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a flexible substrate adapted to be coupled to a portion of the structure;
a plurality of carbon nanotube (CNT)-based conductors operatively positioned on said substrate and arranged side-by-side to one another, said plurality of CNT-based conductors being coated with a gas-impermeable membrane to reduce pressure sensitivity of said plurality of CNT-based conductors; and
,at least one pair of spaced-apart electrodes, each of said at least one pair of spaced-apart electrodes being coupled to opposing ends of at least one CNT-based conductor, said at least one CNT-based conductor electrically coupling such spaced-apart electrodes to one another;
a portion of each of said plurality of CNT-based conductors spanning between each pair of said spaced-apart electrodes comprising a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis, wherein growth of a crack line experienced by the portion of the structure induces a change in electrical properties of said plurality of CNT-based conductors. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A sensor assembly for detecting crack growth experienced by a structure, comprising:
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a plurality of carbon nanotube (CNT)-based sensors positioned into a close grouping on a portion of the structure, each of said CNT-based sensors comprising (i) a substrate adapted to be coupled to the portion of the structure, said substrate being flexible such that strain experienced by the portion of the structure causes relative strain in said substrate, (ii) a plurality of carbon nanotube (CNT)-based conductors operatively positioned on said substrate and arranged side-by-side to one another, said plurality of CNT-based conductors being coated with a gas-impermeable membrane to reduce pressure sensitivity of said plurality of CNT-based conductors, and (iii) at least one pair of spaced-apart electrodes electrically coupled to opposing ends of said plurality of CNT-based conductors with a portion of each of said plurality of CNT-based conductors spanning between each pair of said spaced-apart electrodes comprising a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis; and
means for monitoring the electrical properties of said plurality of CNT-based sensors over time so as to establish a baseline response when the portion of the structure is experiencing baseline levels of the parameter of strain and to identify any change in the electrical properties from the baseline response, wherein a change in the electrical properties of said plurality of CNT-based sensors is indicative of crack growth experienced by the portion of the structure. - View Dependent Claims (18, 19, 20)
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Specification