Carbon nanotube sheet wrapping muscles
A carbon nanotube (CNT) muscle device includes a first CNT yarn. The first CNT yarn includes: one or more first CNT sheets wrapped in the form of a tube; and a first guest actuation material infiltrating the one or more first CNT sheets.
1. A carbon nanotube (CNT) muscle device comprising:
a first hollow CNT tube, comprising:
a first set of one or more CNT sheets wrapped to form the first hollow CNT tube with a first hollow CNT tube central axis; and
a first thermal-responsive guest actuation material having a first thermal expansion coefficient infiltrating the first set of one or more CNT sheets,
wherein CNTs in the first set of one or more CNT sheets are aligned to a first bias angle with respect to the first hollow CNT tube central axis, the first bias angle ranging from 10° to 80° , and
wherein, in response to heating, a volume of the first thermal-responsive guest actuation material expands to cause a first rotational and/or tensile actuation of the CNT muscle device.
2. The CNT muscle device according to claim 1 , further comprising a core fiber having a second thermal expansion coefficient, wherein the first set of one or more CNT sheets are wrapped around the core fiber.
3. The CNT muscle device according to claim 2 , wherein the second thermal expansion coefficient is less than the first thermal expansion coefficient.
4. The CNT muscle device according to claim 1 , further comprising:
a second hollow CNT tube, comprising:
a second set of one or more CNT sheets wrapped around the first hollow CNT tube to form the second hollow CNT tube; and
a second thermal-responsive guest actuation material having a third thermal expansion coefficient infiltrating the second set of one or more CNT sheets,
wherein the CNTs in the second set of one or more CNT sheets are aligned to a second bias angle with respect to the first hollow CNT tube central axis, and the degree of the first bias angle is different from a degree of the second bias angle.
5. A method of manufacturing a carbon nanotube (CNT) muscle device, the method comprising:
wrapping a first set of one or more CNT sheets around a core fiber; and
infiltrating the first set of one or more CNT sheets with a first thermal-responsive guest actuation material having a first thermal expansion coefficient to create a first hollow CNT tube having a central axis,
wherein CNTs in the first set of one or more CNT sheets are aligned to a first bias angle with respect to the central axis of the first hollow CNT tube, the first bias angle ranging from 10° to 80° , and
wherein, in response to heating, a volume of the first thermal-responsive guest actuation material expands, the expansion causing a rotational and/or tensile actuation of the CNT muscle device.
6. The method according to claim 5 , further comprising:
wrapping a second set of one or more CNT sheets around the first hollow CNT tube; and
infiltrating the second set of one or more CNT sheets with a second thermal-responsive guest actuation material having a third thermal expansion coefficient to form a second hollow CNT tube,
wherein CNTs in the second set of hollow CNT tube are aligned to a second bias angle with respect to the central axis of the first hollow CNT tube, and the degree of the first bias angle is different from a degree of the second bias angle.
7. The method according to claim 5 , further comprising annealing the first hollow CNT tube.
8. The method according to claim 5 , further comprising removing the core fiber from the first hollow CNT tube.
9. The method according to claim 8 , wherein the core fiber is removed by pulling out the core fiber from the first hollow CNT tube.
10. The method according to claim 8 , wherein
the core fiber has a lower melting point than the first set of one or more CNT sheets and the first thermal-responsive guest actuation material, and
the core fiber is removed by being melted away from the first hollow CNT tube through heating the core fiber to a temperature above the melting point of the core fiber and below the melting points of the first set of one or more CNT sheets and the first thermal-responsive guest actuation material.
11. The method according to claim 10 , further comprising applying different pressures across a length of the first hollow CNT tube to remove the melted core fiber.
12. The method according to claim 8 , wherein the core fiber is removed by being chemically etched away.
13. The method according to claim 8 , wherein the core fiber is elastic along a length of the core fiber, and the core fiber is removed by being stretched along the length of the core fiber to reduce a diameter of the core fiber and separate the core fiber from an interior surface of the first hollow CNT tube.
14. The method according to claim 8 , further comprising:
forming a layer of a first coating on the core fiber before wrapping the first set of one or more CNT sheets,
wherein the first coating adheres to an interior surface of the first hollow CNT tube and remains disposed on the interior surface of the first hollow CNT tube after removing the core fiber.
15. The method according to claim 8 , further comprising:
forming a layer of a second coating on an exterior surface of the first hollow CNT tube,
wherein the second coating adheres to and stays on the first hollow CNT tube after removing the core fiber.
16. The CNT muscle device according to claim 4 , wherein the first thermal expansion coefficient is different from the third thermal expansion coefficient.
17. The method according to claim 6 , wherein the first thermal expansion coefficient is different from the third thermal expansion coefficient.
18. The method according to claim 6 , further comprising annealing the second hollow CNT tube.