Carbon nanotube based sensor
A carbon nanotube-based sensor comprises a fabric, and a plurality of carbon nanotubes coated on the fabric. The plurality of carbon nanotubes form a network in a plane of the fabric. At least two tap points are coupled to the plurality of carbon nanotubes coated on the fabric. A first of the plurality of tap points is separated from a second of the plurality of tap points, where the first and second tap points have a resistance there between. Application of a force on the fabric, from outside the plane of the fabric, causes a change in the resistance between the first and second tap points.
1 . A method for determining an applied force, the method comprising:
providing a carbon nanotube/fabric-based sensor comprising:
(i) a non-woven fabric featuring multiple layers of randomly oriented non-conductive fibers;
(ii) a plurality of carbon nanotubes coated on the non-conductive fibers, the plurality of carbon nanotubes forming an electrically conductive network in a plane of the fabric;
(iii) at least two tap points/electrodes coupled to the plurality of carbon nanotubes coated on the fabric, a first of the at least two tap points/electrodes separated from a second of the at least two tap points/electrodes, the first and second tap points/electrodes having an electrical resistance there between; and
(iv) wherein the carbon nanotube/fabric based sensor is sufficiently flexible as to conform to a complex geometry;
receiving a force applied to said carbon nanotube/fabric-based sensor, the force being applied out of the plane of the fabric of the sensor, the force causing a decrease in the electrical resistance as coated fibers in adjacent layers of said multiple layers come into contact with one another, thereby increasing the number of contacts between carbon nanotubes;
measuring the decrease in electrical resistance between said first tap point/electrode and said second tap point/electrode; and
determining the force applied to the plurality of carbon nanotubes coated on the fabric from outside the plane of the fabric from the measured decrease in electrical resistance.
2 . The method of claim 1 , wherein the received force includes a component that is normal to the plane of the fabric.
3 . The method of claim 1 , wherein the plurality of carbon nanotubes coated on the fabric form a shoe insert or a mat and wherein the received force is applied by a foot of a person.
4 . The method of claim 1 , wherein the applied force arises from a change in the pressure of the environment surrounding the fabric.
5 . The method of claim 1 , wherein said fabric is drapeable over a curved component.
6 . The method of claim 1 , wherein said fabric comprises a glass fiber or an aramid fiber.
7 . The method of claim 6 , wherein said fabric comprises 10 to 15 percent by volume of said fiber.
8 . The method of claim 1 , wherein the fabric and the plurality of carbon nanotubes form a robotic skin, or a wearable piece of clothing.
9 . The method of claim 1 , wherein said decrease in electrical resistance of the carbon nanotube/fabric sensor is proportional to an applied force on the sensor.
10 . The method of claim 1 , wherein said decrease in electrical resistance is sensed from the application of force which creates a pressure in a tactile range of less than 10 KPa, object handling and maneuvering ranges of 10 KPa to 100 KPa, and high pressure of approximately 40 MPa.
11 . The method of claim 1 , wherein said at least two tap points/electrodes includes a plurality of tap points/electrodes, and further wherein at least some of the plurality of tap points/electrodes are coupled along a boundary of the plurality of carbon nanotubes coated on the fabric, wherein a pressure map is created by mapping the decrease of electrical resistance between the plurality of tap points/electrodes along the boundary of the fabric.
12 . The method of claim 1 , wherein the fabric has a thickness of less than 1 mm.
13 . The method of claim 1 , further comprising:
prior to the plurality of carbon nanotubes being coated on the fabric, treating the plurality of carbon nanotubes with ozone and polyethyleneimine (PEI) using electrophoretic deposition (EPD).
14 . The method of claim 1 , wherein the nanotubes coated on the fabric involves a process comprising:
dipping the fabric in a solution of the plurality of carbon nanotubes and ultra pure water for a predetermined time at room temperature;
flipping the fabric in the solution for another predetermined time;
drying the dipped fabric; and
laminating the coated fabric as thin sheets.
15 . A method for determining an applied force, the method comprising:
providing a carbon nanotube/fabric-based sensor comprising:
(i) a fabric featuring porosity and multiple layers of non-conductive fibers, wherein the fabric is one of a non-woven fabric, a woven fabric, or a knit fabric;
(ii) a plurality of carbon nanotubes coated on the non-conductive fibers of the fabric, the plurality of carbon nanotubes forming an electrically conductive network of random conductive pathways in a plane of the fabric;
(iii) at least two tap points/electrodes coupled to the plurality of carbon nanotubes coated on the fabric, a first of the at least two tap points/electrodes separated from a second of the at least two tap points/electrodes, the first and second tap points/electrodes having an electrical resistance there between; and
(iv) wherein the carbon nanotube/fabric based sensor is sufficiently flexible as to conform to a complex geometry;
receiving a force applied to said carbon nanotube/fabric-based sensor, the force being applied out of the plane of the fabric of the sensor, the force causing a change in the electrical resistance by causing a change in the degree of contact among the carbon nanotubes in adjacent layers of said multiple layers;
measuring the change in electrical resistance between said first tap point/electrode and said second tap point/electrode; and
determining the force applied to the plurality of carbon nanotubes coated on the fabric from outside the plane of the fabric from the measured change in electrical resistance.
16 . The method of claim 15 , wherein said fabric is breathable.
17 . The method of claim 15 , wherein the fabric and the plurality of carbon nanotubes form a shoe insert, a mat, a robotic skin, or a wearable piece of clothing.
18 . The method of claim 15 , wherein a change in resistance of the sensor is proportional to an applied force on the sensor.
19 . The method of claim 15 , wherein the change in resistance is sensed from the application of force which creates a pressure in a tactile range of less than 10 KPa, object handling and maneuvering ranges of 10 KPa to 100 KPa, and high pressure of approximately 40 MPa.
20 . The method of claim 15 , wherein said at least two tap points/electrodes comprises a plurality of tap points/electrodes coupled along a boundary of the plurality of carbon nanotubes coated on the fabric, wherein a pressure map is created by mapping the change of electrical resistance between the plurality of tap points/electrodes along the boundary of the fabric.
21 . The method of claim 15 , wherein the fabric has a thickness of less than 1 mm.
22 . The method of claim 15 , wherein said non-conductive fibers make up 10 to 15 percent by volume of the fabric.
23 . The method of claim 15 , wherein said carbon nanotube coating wraps around the non-conductive fibers.
24 . The method of claim 15 , wherein the non-woven fabric comprises a glass fiber or an aramid fiber.
25 . The method of claim 24 , wherein the aramid fiber includes randomly oriented short fibers.
26 . The method of claim 15 , further comprising:
prior to the plurality of carbon nanotubes being coated on the fabric, treating the plurality of carbon nanotubes with ozone and polyethyleneimine (PEI) using electrophoretic deposition (EPD).
27 . The method of claim 15 , wherein the nanotubes coated on the fabric involves a process comprising:
dipping the fabric in a solution of the plurality of carbon nanotubes and ultra pure water for a predetermined time at room temperature;
flipping the fabric in the solution for another predetermined time;
drying the dipped fabric; and
laminating the coated fabric as thin sheets.
28 . A method for determining an applied force, the method comprising:
providing a fabric/carbon nanotube-based sensor comprising:
(i) a fabric featuring multiple layers of non-conductive fibers;
(ii) a plurality of carbon nanotubes coated on the non-conductive fibers of the fabric, the plurality of carbon nanotubes forming an electrically conductive network of random electrical pathways in a plane of the fabric;
(iii) at least two tap points/electrodes coupled to the plurality of carbon nanotubes coated on the fabric, a first of the at least two tap points/electrodes separated from a second of the at least two tap points/electrodes, the first and second tap points/electrodes having an electrical resistance there between; and
(iv) wherein the fabric/carbon nanotube based sensor is sufficiently flexible as to conform to a complex geometry;
receiving a force applied to said fabric/carbon nanotube-based sensor, the force being applied out of the plane of the fabric of the sensor, the force causing a decrease in the electrical resistance as coated fibers in adjacent layers of said multiple layers come into contact with one another, thereby increasing the number of contacts between carbon nanotubes;
measuring the decrease in electrical resistance between said first tap point/electrode and said second tap point/electrode; and
determining the force applied to the plurality of carbon nanotubes coated on the fabric from outside the plane of the fabric from the measured decrease in electrical resistance.
29 . The method of claim 28 , wherein said fabric comprises a non-woven fabric featuring randomly oriented short fibers.
30 . The method of claim 28 , wherein said fabric comprises a random fiber architecture.
31 . The method of claim 30 , wherein the fabric and the plurality of carbon nanotubes form a shoe insert, a mat, a robotic skin, or a wearable piece of clothing.
32 . The method of claim 29 , wherein said decrease in electrical resistance of the sensor is proportional to an applied force on the sensor.
33 . The method of claim 30 , wherein the application of force can create a pressure in a tactile range of less than 10 KPa, object handling and maneuvering range of 10 KPa to 100 KPa, or high pressure of approximately 40 Mpa, and further wherein the fabric/carbon nanotube sensor can sense each of these pressure ranges via the decrease in electrical resistance.
34 . The method of claim 29 , wherein said at least two tap points/electrodes comprises a plurality of tap points/electrodes coupled along a boundary of the plurality of carbon nanotubes coated on the fabric, wherein a pressure map is created by mapping the decrease of electrical resistance between the plurality of tap points/electrodes along the boundary of the fabric.
35 . The method of claim 30 , wherein the fabric has a thickness of less than 1 mm.
36 . The method of claim 28 , wherein the fabric is one of a non-woven fabric, a woven fabric, or a knit fabric.
37 . The method of claim 36 , wherein the non-woven fabric comprises a glass fiber or an aramid fiber.
38 . The method of claim 37 , wherein the aramid fiber includes of randomly oriented short fibers.
39 . The method of claim 37 , wherein said fabric comprises 10 to 15 percent by volume of said fiber.
40 . The method of claim 29 , wherein said fabric/carbon nanotube sensor comprises porosity.
41 . The method of claim 30 , further comprising:
prior to the plurality of carbon nanotubes being coated on the fabric, treating the plurality of carbon nanotubes with ozone and polyethyleneimine (PEI) using electrophoretic deposition (EPD).
42 . The method of claim 29 , wherein the nanotubes coated on the fabric involves a process comprising:
dipping the fabric in a solution of the plurality of carbon nanotubes and ultra pure water for a predetermined time at room temperature;
flipping the fabric in the solution for another predetermined time;
drying the dipped fabric; and
laminating the coated fabric as thin sheets.
43 . The method of claim 15 , wherein said force causes a decrease in said electrical resistance.
44 . The method of claim 1 , wherein said electrically conductive network comprises random conductive pathways.