Carbon nanotube-based sensor and method for detection of crack growth in a structure

A method of detecting crack growth experienced by a structure, said method comprising the steps of:

• embedding a plurality of carbon nanotube (CNT)-based sensors into a close grouping in 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.

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, including arranging said plurality of CNT-based sensors such that the axis of sensitivity associated with each one of said CNT-based sensors is at an orientation unique to the axis of sensitivity of each of the other of said CNT-based sensors within the close grouping of CNT-based sensors, 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.

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 elcetrical 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, including individually addressing each one of said CNT-based sensors in an ordered matrix, 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.

A sensor for detecting crack growth in a structure, comprising:

• 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.

A sensor assembly for detecting crack growth experienced by a structure, comprising:

• 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 aas-imnermeable 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.

A sensor assembly for detecting crack growth experienced by a structure, comprising:

• 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 said means for monitoring includes individually addressing each one of said CNT-based sensors in an ordered matrix, and wherein a change in the electrical properties of said plurality of CNT-based sensors is indicative of crack growth experienced byte portion of the structure.

A sensor assembly for detecting crack growth experienced by a structure, comprising:

• a plurality of carbon nanotube (CNT)-based sensors positioned into a close grouping on a portion of the structure, wherein said plurality of CNT-based sensors are positioned such that the axis of sensitivity associated with each one of said CNT-based sensors is at an orientation unique to the axis of sensitivity of each of the other of said CNT-based sensors for the close grouping of plurality of CNT-based sensors. 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 identil$ 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.

A sensor assembly for detecting crack growth experienced by a structure, comprising:

• multiple close groupings of a plurality of carbon nanotube (CNT)-based sensors positioned in a dense, ordered arrangement 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 identies 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.