Muscles that wrap carbon nanotube sheets

Abstract

To provide artificial muscle actuators that may have advantages over small motors because of greatly simplified engineering and lower product costs.SOLUTION: 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.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to U.S. Provisional Application No. 62 / 577,512, filed on 26 October 2017, and U.S. Provisional Application No. 62 / 588,034, filed on 17 November 2017, the contents of which are incorporated by reference in their entirety. [Background technology]

[0002] Thermally driven torsional actuators based on twisted polymer fibers and yarns, as well as carbon nanotube (CNT) fibers and yarns, have a wide range of applications. Artificial muscle actuators, also known as artificial muscle devices, which include twisted polymers and / or coiled polymers, offer advantages such as low cost, high productivity, and simple design. Artificial muscle actuators may have advantages over small motors due to their highly simplified engineering and lower product costs. [Overview of the project]

[0003] In one embodiment, the embodiments disclosed herein relate to a carbon nanotube (CNT) muscle device comprising a first CNT yarn. The first CNT yarn comprises one or more first CNT sheets wrapped in the form of a tube, and a first guest activating material permeating one or more first CNT sheets.

[0004] In one embodiment, the embodiments disclosed herein relate to a method for manufacturing a CNT muscle device. The method comprises wrapping one or more first CNT sheets around a core fiber, and impregnating one or more first CNT sheets with a first guest activating material to produce a first CNT yarn.

[0005] Other aspects and advantages of one or more embodiments disclosed herein will become apparent from the following description and the appended claims. [Brief explanation of the drawing]

[0006] [Figure 1] One or more embodiments of the present invention are shown, illustrating a carbon nanotube (CNT) artificial muscle device. [Figure 2] A cross-sectional view of a CNT artificial muscle device is shown according to one or more embodiments of the present invention. [Figure 3] This demonstrates wrapping a CNT sheet in a CNT artificial muscle device according to one or more embodiments of the present invention. [Figure 4] One or more embodiments of the present invention are shown, illustrating a CNT artificial muscle device. [Figure 5] A graph is shown according to one or more embodiments of the present invention. [Figure 6] Cross-sectional and side views of a CNT artificial muscle device are shown according to one or more embodiments of the present invention. [Figure 7] Cross-sectional and side views of a CNT artificial muscle device are shown according to one or more embodiments of the present invention. [Figure 8] Implementation examples are shown according to one or more embodiments of the present invention. [Figure 9] A flowchart is shown according to one or more embodiments of the present invention. [Modes for carrying out the invention]

[0007] Specific embodiments of the present invention are described in detail herein with reference to the accompanying drawings. Similar elements in various figures are indicated by the same reference numerals for consistency.

[0008] The following detailed description of embodiments of the present invention includes many specific details to provide a more complete understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be carried out without these specific details. In other examples, well-known features are not described in detail to avoid unnecessarily complicating the description.

[0009] Generally, embodiments of the present invention relate to carbon nanotube (CNT) artificial muscle devices and methods for manufacturing CNT artificial muscle devices.

[0010] Figure 1 shows a CNT artificial muscle device (hereinafter referred to as CNT muscle device (100)) including CNT yarn (102) arranged around a core fiber (104).

[0011] The CNT yarn (102) shown in Figure 1 includes one or more CNT sheets that wrap around a core fiber (104). Each CNT sheet is a thin sheet of multiple adjacent CNTs. In one or more embodiments, the CNT sheets may be 0.2 mm or wider.

[0012] In one or more embodiments, the CNT sheet may be wrapped to generate a bias angle "θ" with respect to the central access "C" of the CNT muscle device (100). For example, a bias angle of 0° corresponds to a CNT sheet oriented parallel to C, and a bias angle of 90° corresponds to a CNT sheet oriented perpendicular to C.

[0013] In one or more embodiments, the bias angle may be given by the following equation (1): (1) θ = tan ー1 (2πrT).

[0014] In equation (1), "r" is the radial distance between the CNT sheet and C, and "T" is the number of twists (rotations) per meter.

[0015] In one or more embodiments, the core fibers (104) may be any fiber having mechanical strength (i.e., stiffness) selected based on the design or functionality of the CNT muscle device (100). For example, if the core fibers (104) are made from a rigid material, the mechanical strength of the CNT muscle device (100) may be increased, but the flexibility of the CNT muscle device (100) may be hindered.

[0016] In one or more embodiments, the core fiber (104) can be from various polymer fibers, metal wires, carbon fibers, glass fibers, basalt, but cannot be limited thereto. Examples of core fibers include, but are not limited to, fibers, optical fibers, natural fibers / yarns, another CNT yarn, or their tow and ply. Since the CNT yarn can have good mechanical strength and good flexibility, the CNT yarn (for example, the CNT yarn disclosed in the embodiments of the present specification) may be used as the core fiber.

[0017] In one or more embodiments, in the case where the core fiber (104) is a metal wire, the core fiber (104) can be a metal wire such as tungsten, copper, or a metal braid, but cannot be limited thereto. The metal wire can provide mechanical strength (i.e., rigidity) to the CNT muscle device (100) and can provide a high conduction path. This high conduction path can be used to activate or anneal the CNT muscle device (100).

[0018] In one or more embodiments, the diameter of the core fiber (104) may be selected based on the desired tensile strength and / or rigidity of the CNT muscle device (100).

[0019] FIG. 2 shows a cross-sectional view of a CNT muscle device (200) including a core fiber (206) and a CNT yarn (202) disposed around the core fiber (206). The CNT yarn (202) includes one or more CNT sheets (204) wrapped around the core fiber (206) and a guest activation material (208) penetrating into the CNT sheets (204). In one or more embodiments, the guest activation material (208) can penetrate throughout the CNT sheets (204). In other embodiments, the guest activation material (208) can penetrate into a part of the CNT sheets (204).

[0020] For simplicity, Figure 2 shows the CNT sheets (204) and the guest activating material (208) as separate, adjacent layers. However, the CNT sheets (204) and the guest activating material (208) may not be separate, as they can be constructed to form a highly porous CNT layer by the guest activating material (208) penetrating into the gaps between the CNT sheets (204). These features and any of the cavities in the CNT layer may have dimensions ranging from a few nanometers to a few micrometers (μm).

[0021] In one or more embodiments, for better penetration of the guest activating material (208) into the CNT sheet (204), the guest activating material (208) may be applied to the CNT sheet (204) while the wrapped CNT sheet (204) is under vacuum. After applying the guest activating material (208), the vacuum is released and the guest activating material (208) is drawn into the CNT sheet (204). This is hereafter referred to as vacuum-assisted penetration.

[0022] In one or more embodiments, the core fiber (206) may be a coil spring (i.e., a coil spring fiber). In one or more embodiments, the advantage of the coil spring fiber may be that it allows for better attraction of the guest activating material (208) into the inner layer of the CNT sheet (204) (i.e., the layer closer to the core fiber (206)).

[0023] In one or more embodiments, when power is supplied to the CNT muscle device (200) (i.e., heated), the CNT muscle device (200) is activated, which means that the CNT muscle device (200) moves in response to the power being supplied to it (e.g., rotates, flexes, stretches, or contracts). In one or more embodiments, the activation of the CNT muscle device (200) is driven by a volume change (i.e., expansion or contraction) of the guest activation material (208). For example, when the guest activation material (208) is heated, the guest activation material (208) may expand. Thus, although the CNT sheets (204) are flexible, they resist stretching, so the bias angle of the CNT sheets (204) provides a rotational and / or tensile motion direction to the volume change of the guest activation material (208), which can cause activation.

[0024] In one or more embodiments, when the CNT muscle device (200) comprises 5 wt% CNT sheet (204) (or CNTs) and 95 wt% guest activating material (208), the CNT muscle device (200) activates and therefore has low tensile strength. However, those skilled in the art will recognize that the volume percentage or mass percentage of the CNT sheet (204) and guest activating material (208) may be selected based on the preferred design or functionality of the CNT muscle device (200).

[0025] In one or more embodiments, an effective method for powering the guest activating material (208) is by heating the guest activating material (208) through the CNT sheet (204) by resistive heating. However, the CNT muscle device (200) may be powered by other methods such as power induction, light absorption, or chemical reactions.

[0026] In one or more embodiments, other conductive materials (e.g., metal wires, CNT wires, graphene) may be wrapped around the CNT muscle device (200) and the guest activating material (208) may be heated.

[0027] In one or more embodiments, the guest activating material (208) may be selected based on, but not limited to, its function of penetrating the CNT sheet (204), its melting point, biocompatibility, chemical resistance, ultra-high temperature resistance (i.e., durability in hot / cold conditions), or thermal expansion.

[0028] In one or more embodiments, a silicone-based rubber may be used as the guest activator (208) because the silicone-based rubber can withstand high temperatures and does not squeeze from the CNT yarn (202) when heated. In one or more embodiments, the guest activator may be Sylgard184, a silicone-based rubber. In one or more other embodiments, the guest activator (208) may be paraffin wax.

[0029] In one or more embodiments, the guest activating material (208) may expand uniformly upon heating. In one or more embodiments, the guest activating material (208) may expand radially. As the coefficient of thermal expansion of the guest activating material (208) increases, the maximum activation amount (activation function) of the CNT muscle device (200) may also increase. In one or more embodiments, a softer guest activating material (208) may provide greater activation but may also provide lower mechanical strength for the CNT muscle device (200).

[0030] In one or more embodiments, the CNT yarn (202) may also include other materials. For example, the guest activation material (208) may include, but is not limited to, elastomers (e.g., silicone rubber, polyurethane, styrene-butadiene copolymer, and natural rubber), fluorinated plastics (e.g., perfluoroalkoxyalkanes (PFA), polytetrafluoroethylene (PTFE), and fluorinated ethylene propylene (FEP)), aramids (e.g., Kevlar® and Nomex), epoxy compounds, polyimides, and paraffin waxes.

[0031] In one or more embodiments, the core fiber (206) may have a thermal expansion coefficient smaller than that of the guest activating material (208). In one or more embodiments, the core fiber (206) may not expand significantly.

[0032] In one or more embodiments, the cross-sectional area of ​​the core fiber (206) may be less than 10% of the total cross-sectional area of ​​the CNT muscle device (200), or less than 1% of the total cross-sectional area of ​​the CNT muscle device (200).

[0033] Figures 3A and 3B illustrate how CNT sheets can be wrapped around a core fiber. In Figures 3A and 3B, three CNT sheets (302) are placed on a core fiber (304). Since the CNT sheets (302) are separated from each other, each CNT sheet (302) can form a CNT layer. By rotating the core fiber (304) (indicated by rotation arrows) and simultaneously pulling it (indicated by straight arrows), the CNT sheets (302) are wrapped around the core fiber (304), creating three continuous CNT layers along the entire length of the core fiber (304).

[0034] In one or more embodiments, a 15-mm wide CNT sheet (302) may be wrapped 10 times around a core fiber (304) that is 1 m long.

[0035] In one or more embodiments, each CNT sheet (302) may be wrapped multiple times on itself, making it impossible to separate the CNT sheets (302) and potentially creating a stack of CNT sheets (302) that cannot be unwrapped.

[0036] In one or more embodiments, the CNTs in each of the CNT sheets (302) may be aligned with each other, or they may be aligned in one direction along the length of the CNT sheet (302) indicated by "D" in Figure 3A.

[0037] In one or more embodiments, the number of CNT sheets (302) may be more or less than three. Furthermore, a single CNT sheet (302) can be wrapped around a core fiber (304) multiple times. For example, a single CNT sheet (302) can be wrapped around a core fiber (304) multiple times by moving the rotating core fiber (304) back and forth in one direction along the X-axis.

[0038] In one or more embodiments, the angle "θ" of the CNT sheet (302) with respect to the core fiber (304) r This is the same as the bias angle "θ" of the CNT sheet, as shown in Figure 1 and discussed above.

[0039] In one or more embodiments, when the CNT sheet (302) is wrapped, there may be a natural drift at θ toward 90°. In one or more embodiments, the drift at θ can be reduced or eliminated by pulling the CNT sheet (302) for a tighter wrap. In one or more embodiments, the pulling speed and diameter of the core fiber (304) depend on the desired θ.

[0040] The CNT sheet (306) may be fluffy. Therefore, as shown in Figure 3A, a compression tool (306) may be used to press the CNT sheet (302) against the core fibers (304). In one or more embodiments, the compression tool (306) may be a blade or a Teflon® rod. However, the compression tool (306) may be something else, based on the preferred manufacture of the CNT muscle device.

[0041] Figure 3B shows the angle "θ" that the CNT sheet (302) makes with the core fiber (304). r1 θ r2 θ r3 Since each of these can be adjusted, the CNT layers fabricated by the CNT sheet (302) may have different bias angles relative to each other. For example, in Figure 3B, θ r3is the bias angle of the outer CNT layer and θ which is the bias angle of the CNT layer below the outer CNT layer r1 and θ r2 is closer to 90°. According to this embodiment, in one or more embodiments, the advantage of this method shown in FIGS. 3A and 3B is that the bias angle of the CNT layer may be accurately controlled as a function of the radius.

[0042] In one or more embodiments, the respective bias angles of the CNT layers may vary over the length of the core fiber (304). For example, θ r may vary while the core fiber (304) is moving along the X-axis.

[0043] In one or more embodiments, the advantage of this method shown in FIGS. 3A and 3B is that the CNT sheet (302) may be wrapped at any desired angle. For example, the CNT sheet (302) may be wrapped to provide a bias angle greater than 80° with respect to the CNT sheet without coiling the CNT muscle device. However, by wrapping the CNT sheet (302) without the core fiber (304), the CNT muscle device may be coiled so that the CNT muscle device is no longer linear but twisted into a helical pattern. Also, this coiling effect is known in the art as the number of turns. The coiling effect for wrapping the CNT sheet (302) without the core fiber (304) may be more likely to occur at a lower bias angle.

[0044] In other embodiments, the bias angle may increase or decrease as a function of the radial distance from the core fiber (304). Thus, it may be advantageous to increase the number of CNT layers so that the bias angle from one CNT layer to another CNT layer can change more smoothly.

[0045] In one or more embodiments, while wrapping one CNT sheet (302), the pulling speed of the core fiber (304), the diameter of the core fiber (306) over the length of the core fiber (306), and θ rBy maintaining a constant, the bias angle of the CNT sheet (302) over the length of the core fiber (306) may be constant. Alternatively, in other embodiments, the bias angle of the CNT sheet (302) over the length of the core fiber (306) may be varied by changing any of these parameters.

[0046] In one or more other embodiments, the CNT sheet (302) may be wrapped such that alternating CNT layers have alternating bias angles. For example, the bias angle may alternate between +45° and -45°.

[0047] In one or more embodiments, as shown in Figures 4A and 4B, the CNT muscle device may include a plurality of CNT yarns having different activation characteristics. For example, the CNT muscle device (400) includes a first CNT yarn (402) arranged around a core fiber (404), and a second CNT yarn (406) arranged around the first CNT yarn (402).

[0048] In one or more embodiments, the first and second CNT yarns (402, 406) may have different types or amounts of guest activating material, different amounts of CNT sheets, different thicknesses, different bias angles, etc., which may determine the activating force of the first and second CNT yarns (402, 406). For example, as shown in Figure 4B, the bias angle "θ1" of the first CNT yarn and the bias angle "θ2" of the second CNT yarn may be different (for example, θ1 may be smaller than θ2).

[0049] In one or more other embodiments, θ1 may be 10° and θ2 may be 70°. In one or more embodiments, θ1 may be 30° and θ2 may be 60°. In one or more embodiments, θ1 may be 60° and θ2 may be 30°.

[0050] In one or more embodiments, a smaller θ1 than θ2 may provide greater activating force for the first CNT yarn (402) than for the second CNT yarn (406). However, there may be other factors determining the relative activating force of the first and second CNT yarns (402, 406), such as the amount and type, thickness, or quantity of guest activating material in the CNT sheets of the first and second CNT yarns (402, 406). For example, in one or more embodiments, one of the first and second CNT yarns (402, 406) may be incorporated without guest activating material. A CNT yarn without guest activating material may not provide activating force, but it may provide mechanical strength for the CNT muscle device (400).

[0051] In one or more embodiments, it may be advantageous to wrap the CNT sheet at a bias angle of approximately 54.73°. This angle is determined using a single helix model described in "Torsional carbon nanotube artificial muscles" by Javad Foroughi et al., published in Science 334.6055, pp. 494-497, 2011. A single helix is ​​a material that is uniformly twisted in the form of a uniform helix. The single helix model is, This is a fundamental model that acts only on a single helix (or single layer) and serves as a good first approximation of the activation mechanism.

[0052] In one or more embodiments, when a CNT yarn allows for a slight increase in length under low tension over the length of the CNT yarn, and when the bias angle is below approximately 54.73°, the CNT yarn tends to untwist during expansion of the guest-activated material. However, when the bias angle is above approximately 54.73°, the twist of the CNT yarn increases. In one or more embodiments, the former case (bias angle below approximately 54.73°) may result in a higher activation than the latter case (bias angle above approximately 54.73°), and this may result in a higher activation, particularly in CNT muscle devices consisting of multiple layers of CNT yarn with various bias angles.

[0053] Figure 5 shows an example of a single-helix model when the volume of the guest-activated material increases by 5%. Under small tension, the length "L" of the CNT yarn (e.g., the lengths of the CNT yarns (100, 200, 400) along the X-axis in Figures 1, 2, and 4A-4B) may increase from the initial length "L0", so the change in length "L / L0" on the horizontal axis of the graph is greater than 1. When the bias angle is less than approximately 54.73°, such as 50° (short dashed line), the relative torsion (n / n0) decreases compared to the case of a bias angle of 54.73° (solid line). When the bias angle is greater than 54.73°, such as 60° (long dashed line), the relative torsion (n / n0) increases compared to the case of a bias angle of 54.73° (solid line). Here, n is the twist of the CNT yarn after the expansion of the guest activation material (i.e., at activation), and n0 is the initial twist of the CNT yarn before expansion, which may be the twist when the CNT yarn was manufactured.

[0054] In one or more embodiments, the bias angle is It may be advantageous to wrap one or more CNT layers around the core fiber while keeping the bias angle no greater than 54.73°. In other embodiments, the bias angle may increase or decrease monotonically as a function of the radial distance from the core fiber. The bias angle may increase or decrease to a maximum bias angle of 54.73°.

[0055] In one or more embodiments, the core fibers may not be twisted, as they may not be required to generate power.

[0056] In one or more embodiments, the bias angle of the CNT yarn may be adjusted to provide a desired combination of activation and strength of the CNT muscle device. In one or more embodiments, exceeding the optimal bias angle (i.e., the bias angle corresponding to maximum activation (e.g., 54.73°)) results in a decrease in the activation force of the CNT yarn as the bias angle increases. In one or more embodiments, the optimal bias angle does not have to be 54.73°.

[0057] In one or more embodiments, the CNTs in a CNT sheet may be aligned along the length of the CNT sheet. In these embodiments, since the CNTs are strongest along their length, these CNT sheets are also strong along their bias angle. Therefore, the relative mechanical strength of the CNT muscle device in the direction along its length (e.g., along the X-axis in Figures 1, 2, and 4A-4B) (i.e., longitudinal strength), and the relative mechanical strength of the CNT muscle device in the direction perpendicular to its length (i.e., radial strength), depend on the bias angle of the CNT yarn. For example, a bias angle closer to 90° provides higher radial strength and lower longitudinal strength, and a bias angle closer to 0° provides the opposite.

[0058] In one or more embodiments, the strength of the artificial muscle device may depend not only on the bias angle of the CNT yarn, but also on the strength and diameter of the core fibers, any treatment performed on the CNT sheet or guest activating material, and additional guest materials other than the guest activating material.

[0059] In one or more embodiments, the CNT yarn may be reinforced to increase the mechanical strength of the CNT muscle device against rupture. However, reinforcing the CNT yarn may reduce the activation of the CNT muscle device.

[0060] Figures 6 and 7 show cross-sectional views (top view in Figures 6-7) and side views (bottom view in Figures 6-7) of a CNT muscle device (600, 700) including CNT yarns (602, 702) arranged around core fibers (604, 704). To reinforce the CNT yarns (602, 702), reinforcing yarns (606, 706) are wound around the CNT yarns (602, 702). In one or more embodiments, the reinforcing yarns (606, 706) may be CNT wires (i.e., braided CNTs) having high torsional strength and good flexibility.

[0061] As shown in Figure 6, the reinforcing yarn (606) may be wound around the CNT yarn (602) such that the reinforcing yarn (606) is aligned to a bias angle. In one or more embodiments, the reinforcing yarn may be wound such that the net bias angle of the reinforcing yarn is 90° (i.e., there is no bias angle). For example, as shown in Figure 7, the reinforcing yarn (706) may be braided with alternating bias angles to create a state with no bias angle. In one or more embodiments, the reinforcing yarn may be braided with random orientation to create a state with no bias angle.

[0062] Figures 6 and 7 show that the reinforcing yarns (606, 706) are placed on the outer surface of the CNT yarns (602, 702). However, in one or more embodiments, the reinforcing yarns (606, 706) may be partially or completely embedded inside the CNT yarns (602, 702). For example, some CNT sheets may be wound, then some reinforcing yarns (606, 706) may be wound on the CNT sheets, and then more CNT sheets may be wound to partially or completely embed the reinforcing yarns (606, 706) into the CNT yarns (602, 702).

[0063] In one or more embodiments, the reinforcing yarn (606, 706) may include, but is not limited to, metal wire or spring. The advantage of embedding the reinforcing yarn (606, 706) is that it reinforces This may involve protecting the reinforcing yarn (606, 706) from corrosive agents that could etch the yarn (606, 706).

[0064] In one or more embodiments, the reinforcing yarns (606, 706) may be wound in a manner similar to wrapping a CNT sheet, as disclosed in one or more embodiments herein. For example, the reinforcing yarns (606, 706) may be wound by the method disclosed with reference to Figures 3A-3B.

[0065] In one or more embodiments, the core fibers may be removed after the CNT muscle device has been fabricated. A hollow CNT muscle device is referred to as a hollow CNT tube.

[0066] CNTs may adhere to many materials they come into contact with. However, in one or more embodiments, core fibers with low surface energy may be selected so that they do not adhere to the CNT yarn, and these core fibers may be easily removed from the CNT yarn. For example, in one or more embodiments, the core fibers may be deformed silicone with low surface energy or coated with silicone. In one or more embodiments, the core fibers may be Teflon® or have a Teflon® coating.

[0067] In one or more embodiments, the core fibers may be made from a material having a melting point lower than the temperature at which the CNTs break (e.g., about 480 degrees Celsius in air) or a melting point lower than that of the guest activating material (e.g., about 200 degrees Celsius for silicone). In these embodiments, the core fibers may be removed by melting and being discharged. In one or more embodiments, a pressure difference along the length of the CNT yarn may be applied to assist in the discharge of the melted core fibers.

[0068] In one or more embodiments, the CNT rupture temperature may be raised to above 2000 degrees Celsius by applying heat in a vacuum or in an inert gas (e.g., argon).

[0069] In one or more embodiments, the core fibers may be made from a metal with a low melting point, such as solder. In one or more embodiments, the diameter of the solder core fibers may be as small as 50 μm.

[0070] In one or more embodiments, since the CNTs are conductive, the CNT sheet may function as a resistance heater, and the core fibers may be melted using resistance heat.

[0071] In one or more embodiments, the core fibers are removed by etching. For example, the core fibers may be etched off using a strong acid or other corrosive agent. CNTs are resistant to most corrosive agents and can withstand etching. For example, the core fibers may be made of copper and may be etched off with a strong acid such as ferric chloride (FeCl).

[0072] In one or more embodiments, the diameter of the copper core fiber may be 5 μm or less.

[0073] In one or more embodiments, the core fibers may be elastic (e.g., coil spring, rubber) and may be stretched so that the diameter of the core fibers decreases and the core fibers separate from the CNT yarn. In these embodiments, the core fibers may be pulled out from the CNT yarn after being stretched. In one or more embodiments, the core fibers are coil springs containing coils that are close enough to each other so that the CNT sheets can be suspended between the pitches of the coils.

[0074] In one or more embodiments, when the core fiber is a coil spring, if the coiled fiber remains inside the CNT yarn, the CNT muscle device may be considered a hollow CNT tube. In one or more embodiments, the advantage of the coil spring is that it provides good flexibility to the CNT muscle device.

[0075] As shown in Figures 8A and 8B, the inner or outer surface of the hollow CNT tube (800) may be covered with a coating material (802).

[0076] For example, in one or more embodiments, the covering material (802) may be applied to the core fibers, and then the CNT yarn (804) may be wrapped around the covered core fibers. As shown in Figure 8A, the covering material (802) must be adhered to the CNT yarn (804) so ​​that after the core fibers are removed, the covering material (802) remains covering the inner surface of the CNT yarn (804).

[0077] In another embodiment according to one or more embodiments, as shown in Figure 8B, the covering material (802) may cover the outer surface of the CNT yarn (804) with or without the core fibers being removed.

[0078] In one or more embodiments, the covering material on the outer surface of the CNT yarn (804) may be a guest activation material.

[0079] In one or more embodiments, the coating material (802) may be cured (for example, by annealing). In one or more embodiments, the coating material (802) may be annealed at a temperature below the melting point of the coating material (802).

[0080] In one or more embodiments, CNT sheets may be wrapped so that they simultaneously contain other materials. For example, as shown in Figure 8C, CNT sheets may be wrapped so that a CNT yarn (804) contains one or more graphene layers (806). The graphene layers (806) may be, but are not limited to, graphene sheets, graphene flakes, graphene oxide sheets, graphene oxide flakes, or graphene nanoplatelets.

[0081] In one or more embodiments, the CNT yarn (804) may include a graphene layer (806) as an alternative to the guest activation material, which can prevent fluid from leaking from the walls of the hollow CNT tube (800) into the hollow CNT tube (800).

[0082] In one or more embodiments, to better permeate the guest activation material into the CNT sheet of the hollow CNT tube, The pressure inside the hollow CNT tube can be adjusted to be lower than the pressure outside the hollow CNT tube, so that the guest activating material can be drawn from the outer portion to the inner portion of the hollow CNT tube. For example, a vacuum may be applied to the inner hollow portion of the hollow CNT tube (i.e., the portion from which the core fibers are removed).

[0083] In one or more embodiments, an advantage of the hollow CNT tube is that it may have high mechanical strength (e.g., torsional strength), but the hollow CNT tube may be designed to have a very small inner diameter. For example, in one or more embodiments, the inner diameter of the hollow CNT tube may be less than 5 μm.

[0084] In one or more embodiments, the CNT sheet may be wrapped such that the CNT yarn has a net bias angle that causes the hollow CNT tube to ignite. Alternatively, in one or more embodiments, the CNT yarn may not have a bias angle, so the hollow CNT tube does not ignite. For example, randomly oriented CNT sheets produced by a filtration method, a sock method, or an electrospinning method may be wrapped according to one or more embodiments. In one or more embodiments, a hollow CNT tube without a bias angle may be used as a pipe.

[0085] In one or more embodiments, the hollow CNT tube may be reinforced to prevent twisting. For example, the CNT wires disclosed above may be arranged around the hollow CNT activating device in a braided or other pattern according to one or more embodiments.

[0086] Figure 9 shows a flowchart illustrating a method for manufacturing a CNT muscle device. In one or more embodiments, one or more of the steps shown in Figure 9 may be omitted, repeated, and / or performed in an order different from that shown in Figure 9. Consequently, the scope of the present invention is not limited to a specific arrangement of the steps shown in Figure 9.

[0087] In step 905, one or more CNT sheets (i.e., the first CNT sheet) are wrapped around the core fibers. For example, as shown in Figures 2 and 3A-3B, CNT sheets (204, 302) are wrapped around core fibers (206, 304). In another embodiment, the CNT sheets may be wrapped to generate bias angles such as θ shown in Figure 1 and θ1 and θ2 shown in Figure 4B.

[0088] In step 910, the first guest activation material may be impregnated into the first CNT sheet to produce the first CNT yarn. For example, the first CNT sheet may be impregnated by a method for impregnating a CNT sheet according to one or more of the embodiments described above.

[0089] In step 915, the first CNT yarn may be annealed. For example, in one or more embodiments, the first CNT yarn may be annealed according to one or more of the above embodiments for annealing the CNT yarn.

[0090] In step 920, an additional CNT sheet (i.e., a second CNT sheet) may be wrapped around the first CNT yarn. For example, the second CNT yarn (406) is placed around the first CNT yarn (402) as shown in Figures 4A-4B. In one or more embodiments, the second CNT sheet may be wrapped according to the method in one or more embodiments described above for wrapping the CNT sheet.

[0091] In step 925, the second guest activating material may be impregnated into the second CNT sheet to produce a second CNT yarn. For example, as shown in Figures 4A-4B, the guest activating material may be impregnated into the second CNT yarn (406) which is arranged around the first CNT yarn (402). In one or more embodiments, the second guest activating material may be impregnated according to the method in one or more embodiments described above for impregnating the guest activating material.

[0092] In one or more embodiments, the first and second guest activating materials may be made from the same material. Alternatively, in other embodiments, the first and second guest activating materials may be made from different materials.

[0093] In step 930, the second CNT yarn may be annealed. For example, the second CNT yarn may be annealed according to one or more of the above embodiments for annealing the CNT yarn. In one or more embodiments, the first and second CNT yarns may be annealed together. Alternatively, in other embodiments, the first and second CNT yarns may be annealed separately (e.g., at different temperatures, annealing times, or annealing environments).

[0094] In step 935, the core fibers may be removed from the first CNT yarn. For example, the core fibers may be removed from the CNT yarn according to one or more embodiments disclosed above.

[0095] Although this disclosure has described only a limited number of embodiments, those skilled in the art who are interested in this disclosure will understand that various other embodiments can be devised without departing from the scope of the invention. Accordingly, the scope of the invention should be limited only by the appended claims.

Claims

1. Carbon nanotube (CNT) muscle device, The first hollow CNT tube, A first set of one or more CNT sheets wrapped to form the first hollow CNT tube having the central axis of the first hollow CNT tube, A first thermally responsive guest activation material having a first thermal expansion coefficient that penetrates one or more CNT sheets of the first set, It comprises a first hollow CNT tube equipped with, The CNTs in one or more CNT sheets of the first set are aligned to a first bias angle with respect to the central axis of the first hollow CNT tube, and the first bias angle is in the range of 10° to 60°. A CNT muscle device in which, in response to heat, the volume of the first thermally responsive guest-activated material expands, causing a first rotational and / or tensile motion of the CNT muscle device.

2. The CNT muscle device according to claim 1, further comprising core fibers having a second coefficient of thermal expansion, wherein one or more CNT sheets of the first set are wrapped around the core fibers.

3. The CNT muscle device according to claim 2, wherein the second thermal expansion coefficient is smaller than the first thermal expansion coefficient.

4. The second hollow CNT tube, A second set of one or more CNT sheets that are wrapped around the first hollow CNT tube to form the second hollow CNT tube, A second thermally responsive guest activation material having a third thermal expansion coefficient that penetrates one or more CNT sheets of the second set, It further comprises a second hollow CNT tube, The CNT muscle device according to claim 1, wherein the CNTs in one or more CNT sheets of the second set 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 the degree of the second bias angle.

5. A method for manufacturing carbon nanotube (CNT) muscle devices, The steps include wrapping one or more CNT sheets of the first set around the core fiber, The steps include: impregnating one or more CNT sheets of the first set with a first thermally responsive guest activation material having a first thermal expansion coefficient to produce a first hollow CNT tube having a central axis; Equipped with, The CNTs in one or more CNT sheets of the first set are aligned to a first bias angle with respect to the central axis of the first hollow CNT tube, and the first bias angle is in the range of 10° to 60°. A method wherein, in response to heat, the volume of the first thermally responsive guest-activated material expands, and the expansion causes rotational and / or tensile motion of the CNT muscle device.

6. The steps include wrapping one or more CNT sheets from a second set around the first hollow CNT tube, The steps include: impregnating one or more CNT sheets of the second set with a second thermally responsive guest activation material having a third thermal expansion coefficient to form a second hollow CNT tube; Furthermore, The method according to claim 5, wherein the CNTs in the second set of hollow CNT tubes 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 the degree of the second bias angle.

7. The method according to claim 5, further comprising the step of annealing the first hollow CNT tube.

8. The method according to claim 5, further comprising the step of removing the core fibers from the first hollow CNT tube.

9. The method according to claim 8, wherein the core fibers are removed by pulling them out of the first hollow CNT tube.

10. The core fiber has a lower melting point than one or more first CNT sheets of the first set and the first thermally responsive guest activation material. The method according to claim 8, wherein the core fibers are removed by melting and removing them from the first hollow CNT tube through the step of heating the core fibers to a temperature above the melting point of the core fibers, and below the melting point of one or more first CNT sheets of the first set and the first thermally responsive guest activation material.

11. The method according to claim 10, further comprising the step of applying different pressures over the length of the first hollow CNT tube to remove the melted core fibers.

12. The method according to claim 8, wherein the core fibers are removed by chemical etching.

13. The method according to claim 8, wherein the core fiber is elastic along the length of the core fiber, and the core fiber is removed by stretching along the length of the core fiber, reducing the diameter of the core fiber, and separating the core fiber from the inner surface of the first hollow CNT tube.

14. The step of forming a first coating layer on the core fibers before wrapping one or more CNT sheets of the first set, The method according to claim 8, wherein the first coating is adhered to the inner surface of the first hollow CNT tube and remains positioned on the inner surface of the first hollow CNT tube after the core fibers are removed.

15. The method further comprises the step of forming a second coating layer on the outer surface of the first hollow CNT tube, The method according to claim 8, wherein the second coating is adhered to the first hollow CNT tube and remains on the first hollow CNT tube after the core fibers are removed.

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 the step of annealing the second hollow CNT tube.

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