Transfer of nanofiber forests between substrates

Abstract

To provide techniques for transferring nanofiber forests, using transfer films that lack conventional adhesives at the substrate-nanofiber forest interface.SOLUTION: A nanofiber assembly comprises: a transfer film comprising a coating on a carrier and having bond strength; and a nanofiber forest comprising a plurality of nanofibers, the nanofiber forest disposed on the transfer film, and the nanofiber forest free of adhesive. The nanofibers comprise an arcuate portion, a straight portion, an angled portion, and an open end of the straight portion. The angled portion lies between the arcuate portion and the straight portion. The open end lies at an end of the straight portion opposite the angled portion. The nanofibers are perpendicular with respect to the transfer films.SELECTED DRAWING: Figure 2C

Description

[Technical Field]

[0001] The present disclosure relates generally to nanofibers. Specifically, the present disclosure relates to nanofibers between substrates. It involves transferring a fiber forest. [Background technology]

[0002] Multiple nanofiber or carbon nanotube "forests" can be interconnected on a substrate. a plurality of nanofibers aligned substantially parallel to the surface of the substrate and oriented substantially perpendicular to the surface of the substrate; or carbon nanotube arrays. Nanofiber forests are composed of catalyst particles. growing nanotubes by placing them on a long substrate and Various methods include heating in a furnace and supplying a fuel compound to the heated catalyst and substrate. The nanofibers can be formed in any of a variety of ways. They grow perpendicularly from the catalyst particles in a substantially parallel array. Summary of the Invention

[0003] Example 1 is a nanofiber assembly. The binder comprises a first roller having a non-adhesive coating on a carrier and a first bonding strength. a photosensitive film and a second adhesive-free film having a bond strength greater than the first bond strength; a transfer film and a nanofiber forest including a plurality of nanofibers, and a second transfer film, and a nanofiber film containing no adhesive is disposed between the first transfer film and the second transfer film. -It is equipped with a forest.

[0004] Example 2 includes the subject matter of Example 1, except that the first transfer film comprises wax paper. Furthermore, the non-adhesive coating is paraffin wax, and the second transfer film is It is silicone rubber.

[0005] Example 3 includes the subject matter of either Example 1 or Example 2, further comprising: , the second transfer film, and the nanofiber forest are configured as a roll.

[0006] Example 4 includes the subject matter of one of the preceding examples and is a multiple nanofibre The bar is attached to at least one adjacent surface of the first transfer film and the second transfer film. The optics are aligned in a common direction between 0° and 5°.

[0007] Example 5 includes the subject matter of any of the preceding examples and is directed to a composite nanofiber forest. The nanofibers include arcuate and straight sections.

[0008] Example 6 includes the subject matter of Example 5, with the bow adjacent the first transfer film.

[0009] Example 7 includes the subject matter of Example 5, with the bow adjacent to a second transfer film.

[0010] Example 8 includes the subject matter of Example 5, but includes an angled port between the arcuate and straight sections. ion).

[0011] Example 9 includes the subject matter of any of the preceding examples, wherein the nanofiber forest: It contains two or more stacked nanofiber forests.

[0012] Example 10 includes the subject matter of any of the preceding examples, wherein the nanofibers are The transfer film is physically bonded to the first transfer film with a bonding strength greater than the first bonding strength. The combined strength of the two films is physically bonded to the second transfer film.

[0013] Example 11 includes the subject matter of Example 10, with the first bond strength being 2 Newtons / 2 The bond strength is less than 5 mm and the second bond strength is greater than 2 Newtons / 25 mm.

[0014] Example 12 has a non-adhesive coating on the carrier, and has a first bonding strength. providing a first transfer film having a first bonding strength, the first transfer film being adhesive-free; providing a second transfer film having a second bonding strength greater than the first bonding strength; disposing a nanofiber forest comprising a number of nanofibers, The fiber forest contacts the first transfer film and the second transfer film, and the first The nanofiber forest is placed between the transfer film and the second transfer film, and adhered to the film. and wherein the method does not include the steps of:

[0015] Example 13 includes the subject matter of Example 12, except that the compressive force is applied to the first transfer film and the second transfer film. and applying a compressive force to the transfer film, and forming a nanofiber forest in response to the applied compressive force. The nanofibers of the first transfer film and the second transfer film are attached to at least one of the first transfer film and the second transfer film. and aligning the surfaces in a common direction at 0° to 5° relative to the adjacent surface. nothing.

[0016] Example 14 includes the subject matter of either Example 12 or 13, and the first transcription filter a film, a second transfer film, and a nanofilm between the first transfer film and the second transfer film; The method further includes the step of winding the entire length of the fiber forest into a roll.

[0017] Example 15 includes the subject matter of either Example 12 or 13, and is further modified to include nanofiber fibers. Forest's nanofibers have open ends and tangled ends.

[0018] Example 16 includes the subject matter of Example 15, and does not include the first transfer film or the second transfer film. removing one of the films to expose the surface of the nanofiber forest; The surface comprises one of the open ends or tangled ends of the nanofibers in the nanofiber forest. The nanofiber forest does not contain adhesive, and the exposed surface is placed on the final substrate. and

[0019] Example 17 includes the subject matter of Example 16, except that the final substrate is a nanofiber substrate without an adhesive. It includes an adhesive layer that is used to adhere the fiber forest to the final substrate.

[0020] Example 18 includes the subject matter of Example 16, and does not include the first transfer film or the second transfer film. The method further includes a step of removing one of the remaining films, the removing step being performed by removing a nanofilm. The multiple nanofibers in the fiber forest are aligned at a distance of 0° to 5° from the surface of the final substrate. The orientation is in the direction of

[0021] Example 19 is a nanofiber assembly. The assembly includes a transfer film having a non-adhesive coating on a carrier and having bonding strength. and a nanofiber forest comprising a plurality of nanofibers, the nanofiber forest being disposed on a transfer film. and an adhesive-free nanofiber forest.

[0022] Example 20 includes the subject matter of Example 19, except that the non-stick coating is paraffin wax. Includes custard.

[0023] Example 21 includes the subject matter of either Example 19 or 20, and further includes a plurality of nanofibers. The bars are perpendicular to the surface of the transfer film.

[0024] Example 22 includes the subject matter of any of Examples 19-21, further comprising a plurality of nanofibers. has an arcuate portion and a straight portion that includes an open end.

[0025] Example 23 includes the subject matter of any of Examples 19 to 22, wherein the bow is a transfer film. The open end of the straight portion is exposed.

[0026] Example 24 includes the subject matter of any of Examples 19 to 22, and the straight portion is a transfer film. The arcuate portion is exposed.

[0027] Example 25 includes the subject matter of any of Examples 19 to 24, and is further modified to include a nanofiber fiber. The structure contains two or more stacked nanofiber forests.

[0028] Example 26 is a nanofiber assembly. The assembly includes a first adhesive-free transfer film and a nanofiber transfer film having a plurality of nanofibers. a first adhesive-free transfer film, the first adhesive-free transfer film being physically bonded to the first adhesive-free transfer film; It is equipped with a nanofiber forest.

[0029] Example 27 includes the subject matter of Example 26, except that the first adhesive-free transfer film is an elastic polyester. Including Ma.

[0030] Example 28 includes the subject matter of either Example 26 or 27, and includes a first adhesive-free transfer. A second non-adhesive layer is physically bonded to the surface of the nanofiber forest on the opposite side of the photoresist film. It further includes an adhesive transfer film.

[0031] Example 29 includes the subject matter of Example 28, but includes a first adhesive-free transfer film, a second adhesive-free transfer film, and a The adhesive transfer film and nanofiber forest are wound into a roll.

[0032] Example 30 includes the subject matter of Example 28, wherein the nanofibers have a first bond strength. A second bond that is physically bonded to one adhesive-free transfer film and has a strength greater than the first bond. It is physically bonded to a second adhesive-free transfer film with great strength.

[0033] Example 31 includes the subject matter of Example 30, with the first bond strength being 2 Newtons / 2 The bond strength is less than 5 mm and the second bond strength is greater than 2 Newtons / 25 mm.

[0034] Example 32 includes the subject matter of any of Examples 26-31 and is a forest nanofabric. The optical fiber is aligned in a common direction between 0° and 5° to the adjacent surface of the first adhesive-free transfer film. will be listed.

[0035] Example 33 includes the subject matter of any of Examples 26 to 32, and is further modified to include a nanofiber fiber. The structure contains two or more stacked nanofiber forests.

[0036] Example 34 includes the subject matter of any of Examples 26 to 33, and is a nanofiber fiber. The nanofibers of the present invention comprise straight sections, arcuate sections, and sloped sections between the straight and arcuate sections. .

[0037] Example 35 is a nanofiber assembly. The assembly comprises an adhesive layer containing adhesion molecules, a diffusion barrier on the adhesive layer, and a nanoparticle in contact with the diffusion barrier. The diffusion barrier is made up of an adhesive layer and a nanofiber forest. Prevents the diffusion of adhesion molecules to the

[0038] Example 36 includes the subject matter of Example 35, wherein the diffusion barrier is a carbonized adhesion layer. layer of adhesive).

[0039] Example 37 includes the subject matter of Example 36, wherein the interface between the adhesive layer and the carbonized adhesive layer is The nanofiber forest is on the opposite side of the adhesive layer.

[0040] Example 38 includes the subject matter of any of Examples 35-37, further comprising: further comprising a release liner on the second, opposite surface.

[0041] Example 39 includes the subject matter of any of Examples 35 to 38, and further includes a nanofiber forest. The sheet further includes a transfer film on the surface opposite the carbonized adhesive layer. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 is a method flow diagram illustrating an exemplary method for transferring a nanofiber forest between substrates, according to embodiments. [Figure 2A] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2B] 1 is a perspective scanning electron microscope (SEM) image of a carbon nanotube forest having a plurality of individual nanotubes, each nanotube having a straight section and an arcuate section, according to one embodiment. [Figure 2C] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2D] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2E] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2F] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2G] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2H] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2I] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2J] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2K] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 2L] 2A-2C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 1, according to embodiments. [Figure 3]1A-D show side views of a nanofiber forest on a substrate processed according to the exemplary method of FIG. 1 using an alternative first transfer film with an adhesive layer, according to an embodiment. [Figure 4A] FIG. 1 is a schematic side view of a nanofiber forest on an adhesive layer with sloped sections in addition to straight and arcuate sections, in one embodiment. [Figure 4B] 1 is an SEM micrograph of a side view of a nanofiber forest with a slope, according to one embodiment. [Figure 5] FIG. 1 is a method flow diagram illustrating an exemplary method for transferring a nanofiber forest from a stack of nanofiber forests between substrates, according to one embodiment. [Figure 6A] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6B] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6C] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6D] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6E] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6F] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6G] 6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 6H]6A-6C show side views of a nanofiber forest on a substrate at various stages of the exemplary method shown in FIG. 5, according to an embodiment. [Figure 7] 1 is a photomicrograph of an exemplary forest of nanofibers on a substrate, according to one embodiment. [Figure 8] FIG. 1 is a schematic diagram of an exemplary reactor for nanofiber growth, according to one embodiment. [Figure 9] FIG. 1 is a schematic diagram of a nanofiber sheet, in one embodiment. [Figure 10] 1 is an SEM micrograph of a nanofiber sheet pulled from a nanofiber forest, according to one embodiment.

[0043] These figures depict various embodiments of the present disclosure for illustrative purposes only. Many variations, configurations and other embodiments will become apparent from the following detailed description. Please be aware that these figures are not necessarily drawn to scale. Furthermore, it is not intended that the embodiments described below be limited to the specific configurations shown. For example, some figures generally show straight lines, right angles, and smooth surfaces, but the disclosed Actual implementations of the technology described may have less than perfect straight lines and right angles, and some features may be Considering the real-world limitations of the fabrication process, the surface topography may or may not be In short, these figures are provided merely to illustrate exemplary structures. can be. DETAILED DESCRIPTION OF THE INVENTION

[0044] Nanofiber forests have novel mechanical, optical, thermal, and electrical properties ( and the unique combination of these properties) have various technological applications. This makes the production of Nanofiber Forest more convenient, economical and consistent. The improved economics and manufacturing consistency have led to increased interest in nanofiber forests. My spirits continue to soar.

[0045] The novel properties of nanofiber forests are, in some cases, adhesives, oligomers, or The adhesive properties may be affected by the presence of other polymers or molecules. One exemplary source of nanofibers, oligomers, or other molecules is a nanofiber forest. Originating from materials used to adhere to substrates (e.g., flexible polymer sheets) Some of the adhesion molecules are mobile at ambient temperatures (e.g., above 10°C). Therefore, adhesion molecules diffuse or move from the forest-substrate interface into the forest itself. Once the nanofibers are in contact with each other, the nanofibers in the forest can be Furthermore, when placed within hollow nanofibers, adhesion molecules form nanofiber forests. may degrade some of the novel mechanical, optical, thermal, and electrical properties exhibited by There is.

[0046] To overcome this effect caused by adhesives, oligomers, polymers, or other molecules To alternatively avoid this, embodiments of the present disclosure provide a substrate / nanofiber forest There is a lack of adhesive at the interface, or adhesion molecules (and oligomers) to the nanofiber forest. and to a substrate that either contains a diffusion barrier that prevents the diffusion of molecules (such as cellulose and other molecules) Further, the present invention includes techniques for transferring nanofiber forests as described herein. Some of the techniques discussed can be used with a single nanofiber forest in a single layer, This allows the transfer of a single nanofiber forest between substrates. Forests are transferred from the growth substrate to secondary and tertiary substrates. In one embodiment, the techniques described herein can be used to One nanofiber forest can be removed from the stack of layers.

[0047] In another example described below, an adhesive layer is used to treat a carbon nanofiber forest. However, the diffusion of contaminants from the adhesive layer to the nanofiber forest is This is eliminated or reduced by providing a diffusion barrier between the The diffusion barrier is made of carbon-containing materials (including adhesives) that are heated to "carbonize" the carbon-containing material. ) layer.

[0048] [Adhesive-free transfer film] As indicated above, the embodiments of the present disclosure include a first transfer film and a second transfer film. Substrate for transferring the nanofiber forest from the growth substrate to the final substrate using a In one embodiment, the nanofiber forest is formed without the use of adhesives. , can be attached to one or both of the first transfer film and the second transfer film. In one embodiment, one or both of the first transfer film and the second transfer film The adhesive and the nanofiber forest (or stack of nanofiber forests) The barrier layer (alternatively referred to as a diffusion barrier) may include a diffusion barrier between the Adhesion (or adhesion) from the film / nanofiber interface to the nanofiber forest itself The adhesive is not present within the forest itself, so the nanofiber The characteristics of the fiber forest can be maintained. The interface between the forest (or forests) and the first and second transfer films Depending on physical and chemical factors such as the relative strength of the adhesive, nanofibers may be aligned in a common direction. can be aligned.

[0049] In embodiments according to the present disclosure, the exemplary method 100 shown in FIG. 1 and FIG. 2A The corresponding schematic side views shown in FIGS. 2B to 2L show the first and second transfer films. film to transfer the nanofiber forest from the growth substrate to the final substrate. The technology includes a variety of different types of transfer substrates, adhesive alternatives, barrier layers, and related technologies. Some of the adhesives that can be used are described below. Although the term is used to refer to potential contaminants of the rest, possible contaminants are adhesion molecules. It will be appreciated that this includes, but is not limited to, any of the other types of contaminants listed above.

[0050] First, referring to the exemplary method 100 of FIG. 1, and simultaneously referring to corresponding FIGS. 2A-2L, In accordance with this, the method 100 includes growing a carbon nanotube forest disposed on a growth substrate 204. The method begins with a step (104) of providing a nanofiber forest 208. The technique for growing a crystalline silicon layer on a growth substrate 204 is described and shown in the context of FIGS. can be.

[0051] In one example, the nanotube forest is 20 microns to 400 microns, 70 microns ~100 microns, 100 microns ~ 300 microns, 300 microns ~ 400 microns , the average height H (growth substrate 2) in the range of 75 microns to 150 microns 04 to the exposed surface of the nanofiber forest 208) Although the forest embodiments described herein are shown as single-layer forests, Stacked forests (i.e., two or more forests stacked on top of each other) can also be used. It is recognized that overlapping forests (e.g., two forests, three forests) can be The forest (or more forests) is calculated by multiplying the height H by the corresponding multiple of the height H described above. However, the height of each stacked forest is the same as the other forests in the stack. Further, examples of height H and stacked forests are shown in Figures 2A and 2B. 2L, but extends to any of the embodiments described herein.

[0052] In the embodiment shown in FIG. 2A, the nanofibers in the nanofiber forest 208 The straight section 212 is adjacent to the growth substrate 204. The fiber arcuate portion 216 is positioned on the opposite side of the growth substrate 204 from the nanofiber forest 208. These are shown schematically in FIG. 2A and at a magnification of about 300× and As shown in the scanning electron microscope (SEM) image in Figure 2B taken at an accelerating voltage of 10 kV. The straight section of the nanofiber can terminate in an "open end," which is the end of a hollow nanofiber. It is the opening at the end of the nanofiber that provides access to the interior of the fiber. The open ends of the fibers are in a common plane within + / - 5% of the length of the straight section of the nanofiber. The straight sections of the nanofibers in the nanofiber forest are generally aligned with the reference plane. (e.g., the underlying substrate) within + / - 5° of a common orientation. The common direction of the straight nanofibers in the nearly vertical forest is 85° to 95°. The "arch" (also sometimes called the "tangled end") is in the range of 1 / 4000 of a second. is at the opposite end from the open end of the nanofiber. Generally, the tangled end is opposite the growth substrate. The arcuate portion is disposed on the exposed surface of the nanofiber layer. The wire portion bends away from the longitudinal axis. 2. Either the open end 212 or the knotted end 216 is bonded to the final substrate 232 so that The techniques of this disclosure can be adapted to provide a surface that is not exposed, leaving the opposite end exposed.

[0053] Method 100 can then follow one of two sub-methods: The sub-method 106, when performed on the provided nanofiber forest 208 (1 04), and finally, the arcuate end of the straight portion 212 is brought into contact with the exposed surface of the nanofiber forest 208. The substrate can then be optionally placed on a final substrate (140 ). The sub-method 107, when performed on the provided nanofiber forest 208 ( 104), and finally, the opening 216 is positioned on the exposed surface of the nanofiber forest 208. 140 , which can then be optionally placed on a final substrate 232. ).

[0054] As shown in FIG. 2C, the sub-method 106 includes: Applying a first transfer film 220 to the exposed surface of the substrate 208 (104) (108) Alternatively, as also shown in FIG. 2C, a sub-method 107 is provided. A second transfer film 222 is applied to the exposed surface of the nanofiber forest 208 (104). This process begins with step (112) of using nanofiber fibers. The exposed surface of the forest 208 is the nanofiber arch 21 of the nanofiber forest 208. 6. Therefore, the first transfer film 220 (sub-method 106) or the second transfer film Placed in contact with one of the photographic films 222 (sub-method 107) is a photographic film. These are the arcuate portions 216 of the rests 208 .

[0055] In an example, the first transfer film 220 is a packing or substrate coated with a non-adhesive layer. The second transfer film 222 is a film containing an elastically deformable film or substrate. Examples of both the first transfer film 220 and the second transfer film 222 are described below. do.

[0056] As noted above, the first transfer film 220 does not use adhesive but instead is non- An adhesive coating is used to establish a connection with the nanofiber forest 208. In one example, the first transfer film 220 has a non-adhesive bond strength greater than that of the second transfer film 222. a non-adhesive bond strength (or, for brevity, simply "bond strength" herein) less than The non-adhesive bond is either between the nanofiber forest and the transfer film. Examples of non-adhesive bonds include those in which the temporary and releasable connection is achieved without adhesive. Adhesion is not established by chemical interactions, but rather by, among other things, van der Waals forces, mechanical connections (e.g., elastomer gripping or impact), electrostatic forces, surface Decomposition of tension (e.g., water layer, or other volatile or non-volatile liquid or fluid), etc. In one embodiment, such as that shown in FIG. 2C, the first transfer film 2 20 does not include an adhesive. In one example, the first transfer film 220 is a commercially available Some wax paper (e.g., Cut-Rite® Wax Paper) In one example, wax paper (or alternatively, a release liner (i.e., adhesive Bonding with a polymer sheet) used to cover and protect the adhesive layer before application Strength was measured by a 180° peel test (performed according to ASTM D3330 ) 0.1 Newtons / 25mm to 1.5 Newtons / 25mm. This is The adhesion molecules are not in close or direct contact with the nanofiber forest 208, and thus is not transferred to the nanofiber forest, improving the quality of the nanofiber forest. This is due to the pure nanofiber forest described above. This prevents deterioration of the electrical, mechanical, thermal, and optical properties exhibited by the above-mentioned materials.

[0057] In another example, the first transfer film 220 may be made of a non-adhesive material such as paraffin wax. A flexible film (paper, polymer (e.g., polyethylene), or In yet another example, the first transfer film 220 is made of an ASTM 0.1 Newt when measured using a 180° peel test conducted in accordance with D3330 Non-adhesive coating with bond strength of 1.5 Newtons / 25mm to 1.5 Newtons / 25mm Examples of non-adhesive coatings include, but are not limited to, adhesive coatings. A peel label is used to facilitate separation of the backing from the adhesive (e.g., "non-carrier" adhesive). This includes coatings applied to inner backings. One example of such a coating is An illustrative example includes a siloxane coating. Another example is a release liner for an adhesive film. Plastic films (e.g., silicone or polyethylene) are more traditionally used as When a release liner is used as the first transfer film 220, 0, measured using a 180° peel test conducted in accordance with ASTM D3330 Bond strength measured is 1 Newtons / 25mm to 1.5 Newtons / 25mm. In any case, the first transfer film 220 adheres to the substrate by coating rather than chemical attraction. This facilitates a physical connection between the nanofiber forest and the exposed surface of the nanofiber forest.

[0058] In one example, the second transfer film 222 is made of an elastic polymer (e.g., butadiene rubber). In one embodiment, the second transfer film includes an elastically deformable sheet such as that formed by Lum 222 does not contain adhesives, yet Nanofiber Forest 208 In one embodiment, the silicone rubber sheet forms a physical connection with the exposed surface of the silicone rubber sheet. The physical connection between the rubber sheets (or more generally, the elastically deformable sheets) is Before applying the silicone rubber sheet to the exposed surface of the Nanofiber Forest 208, This is facilitated by stretching the nanofiber sheet in one or more directions. After being placed in contact with the forest 208, the stretch is released. By doing so, the silicone rubber sheet can capture some of the Forest 208 nanofibers. can form micron-scale topographical features that collide (or impact) with each other, thus Establish a releasable, physical, adhesive-free connection with the exposed surface of the forest 208. The bond strength of the second transfer film 222 with the fiber forest is In one example, this bond strength is greater than the bond strength of the ASTM standard shown above. Greater than 0.5 Newtons / 25mm, 2 Newtons when measured according to the ns / 25mm or possibly greater than 3Newtons / 25mm be.

[0059] As also shown in FIG. 2C, both sub-methods 106 and 107 involve the growth substrate 204 and and transfer films 220, 222, respectively, to apply a compressive force to the nanofiber forest. This compressive force is indicated by the arrows in FIG. 2C. In one example, the compressive force has a lateral component (the growth substrate 204 and / or the transfer film In either case, the compressive force is applied to the nanofiber foci. The nanofibers of the substrate 208 are then transferred to the growth substrate 204 and the corresponding transfer film 220, This has the effect of reorienting the surface of the substrate 22 so that it is more parallel to the surface facing the substrate 22. "Parallel" refers to the surface of the growth substrate 204 and / or one surface of the transfer film 220, 222. This can refer to nanofibers that are oriented less than 10° from the plane. This reorientation is shown schematically in FIG. 2D. It is shown explicitly.

[0060] In any event, both sub-methods 106 and 107 involve nano-scale processes, as shown in FIG. 2E. The process continues with the step of removing (120) the growth substrate from the fiber forest 208. This exposes the open end 212 of the nanofiber forest 208, allowing the nanofibers The tangled ends of the arched portion 216 of the forest 208 are then attached to the pre-applied transfer film 220. Leave it attached to 22.

[0061] Now, referring to FIG. 2F, the underlying method 106 comprises forming a forest 208 of nanofibers. Continuing with the application (124) of a second transfer film 222 to the open end 212 of the forest 2 The entangled ends 216 of the 08 were previously contacted by the first transfer film 220. Alternatively, the sub-method 107 may include a first transfer fill to the open end 212 of the forest 208. Continuing with the application (128) of the forest 208, the tangle ends 216 of the forest 208 are Previously contacted by film 222. Both sub-method 106 and sub-method 107 On the other hand, the nanofiber forest 208 and the first transfer film 220 (non- The adhesive bond strength between the nanofiber forest 208 and the second transfer film 222 is The (non-adhesive) bond strength between the

[0062] 2G and 2H show assemblies produced by sub-methods 106 and 107, respectively. 2G (corresponding to the sub-method 106) shows different configurations of 224 and 226. Assembly 224 contacts arcuate portion 216 of nanofiber forest 208 so that The first transfer film 220 contacts the second transfer film 222. 2H (corresponding to submethod 107) and includes an open end 212 of forest 208. Assembly 226 contacts arcuate portion 216 of the nanofiber forest so that The second transfer film 222 is attached to the open end 212 of the nanofiber forest. It comes into contact with the photographic film 220.

[0063] Both of the lower methods 106 and 107 result in a strength lower than that of the second transfer film 222. The first transfer film 220 having the combined strength is optionally removed from the corresponding assembly. As shown in FIG. 2I corresponding to submethod 106, the first transfer The step of removing the photographic film 220 (132) removes the arcuate portion of the nanofiber forest. 216 to produce assembly 228. As such, the step of removing the first transfer film 220 (136) is The arcuate portion 216 of the burr forest is exposed, creating the assembly 230 .

[0064] Also shown in FIG. 2I, in one embodiment, the nanofibers of forest 208 are , can be reoriented so as to be perpendicular to the surface of the substrate of the second transfer film 222; and / or an angle smaller than the perpendicular to the surface of the second transfer film 222, and greater than 0° to 10° observed after applying a compressive force to the transfer films 220 and 222. These two different angles are both shown in Figure 2I. The nanofibers after the first transfer film 220 is removed and the second transfer film 222 are The angle between the surfaces is determined, at least in part, by the angle between the first transfer film 220 and the second transfer film 221. The larger the bond strength between the first transfer film 222 and the second transfer film 222, the greater the bond strength between the first transfer film 222 and the second transfer film 222. With the bond strength, the magnitude of the bond strength difference increases between these two transfer films. As this occurs, the first transfer film 220 transfers the nanofibers to the second transfer film 222. This makes it difficult for the nanofibers to reorient themselves perpendicular to the surface, which can be 15° to 85°. This results in a partial realignment of the fibers, resulting in the exposed open ends of the nanofiber forest. A similar situation is shown in Figure 2J.

[0065] In either case, the exposed surface of the nanofiber forest 208 is optionally attached to the final substrate 232. The final substrate 232 may have an adhesive layer 234 disposed thereon. Alternatively, the final substrate 232 may be formed without the use of adhesive. The tangled end of the arcuate portion 216 or the open end of the straight portion 212 of the nanofiber forest 208 The adhesive layer 234 may be attached to either the tangled ends of the nanofiber forest 208. An example of the nanofibers used to attach the nanofibers to the final substrate 232 is shown in Figure 2K. An example where the open end of the forest 208 can be attached directly to the final substrate 232 without adhesive is: As shown in Figure 2L, as noted above, in both the examples shown in Figures 2K and 2L The nanofibers are oriented such that the open ends 212 of the nanofiber forest 208 are in contact with the adhesive. Thus, the nanofiber forest 208 can be attached to the final substrate 232 or The knotted ends 216 may be inverted so that they are attached to the final substrate 232 without adhesive. It is recognized that it is possible.

[0066] In yet another embodiment, the method described above can be used to scan a plurality of nanofiber forests. It can be applied to tack.

[0067] [Transfer film with adhesive layer and diffusion barrier] The method 100, including the sub-methods 106 and 107, comprises a first transfer film 220 and a second transfer film 221. A variety of different types, structures, and compositions of transfer film 222 can be applied. For example, the above-described first transfer film 220 and second transfer film 222 embodiments In addition, the transfer film 300 is applied to the exposed surface of the nanofiber forest 208. As shown in FIG. 3A, the transfer film 300 is adhered onto a release liner 308. In one example, adhesive layer 304 may include an acrylic adhesive, a methacrylate adhesive, or the like. adhesives, epoxies, and non-carrier adhesives (e.g., typically applied to a carrier film after The adhesive may be one or more of the following: a separate adhesive layer attached to a surface of a substrate and protected by a release liner. The bond strength between the nanofiber forest and adhesive layer 304 is measured according to ASTM D3330 0.5 Newtons / 25m, measured by a 180° peel test performed in accordance with m or more, 5 Newtons / 25 mm or more, 7 Newtons / 25 m or more m, 10 Newtons / 25 mm, or 20 Newtons s / 25mm.

[0068] In one embodiment, the adhesive layer 304 is attached to the second transfer film 222 (e.g., silicone rubber). ) has a bond strength greater than that used for (140) nanofiber fiber applied onto (and adhered to) the final substrate 312 In one example of performing method 100 including sub-method 106, The transfer film 300 includes the nanofiber forest arcuate portions 21 on its growth substrate 204. 6 (108) and compressed (116). The growth substrate 204 is then removed ( 120). The second transfer film 222 is exposed by removing (120) the growth substrate 204. 1. The transfer film 208 is then applied to the open end 212 of the transfer film 208. The release liner 308 (rather than the entire film) can then be removed (132) to expose An adhesive layer 304 can be applied to the final substrate 312. A second transfer film 222 (e.g., For example, the silicone rubber layer described above may remain (as shown in FIG. 3B), or can be optionally removed to produce assembly 310 shown in FIG. 3C.

[0069] In another example shown in FIG. 3D, a method 100 including a sub-method 107 includes a first transcription filter. This is done by using a transfer film 300 instead of the film 220. ... The open end of forest 208 is attached to adhesive layer 304, which in turn forms the final substrate 31. In the example shown in FIG. 3D, the first transfer film 220 is removed. Although the first transfer film 220 is removed, this does not have to be the case. Instead, the embodiment described in the context of FIG. 3D may be referred to as assembly 314.

[0070] One feature of the assemblies 310, 314 including the adhesive layer 304 is the nanofiber forest The nanofibers of the strip 208 are configured as shown and described above in terms of straight sections 212 and arcuate sections 211. 6, and includes a sloped portion 404. This configuration is nanofiber forest 2 The nanofibers in 09 are shown schematically in Figure 4A. Scanning electron microscopy of this configuration A scanning electron microscope (SEM) micrograph appears in Figure 4B.

[0071] As shown in FIG. 4A, the nanofiber forest 209 is disposed on the adhesive layer 304. The adhesive layer 304 then adheres the nanofiber forest 209 to the final substrate 312. In this case, the nanofiber forest 209 is made up of straight portions 212 and arcuate portions 216 (in this case (from the previously applied compressive force) and can be flush with adhesive layer 304. (not shown) and a sloped portion 404. One possible mechanism for creating the bevel 404 is that the adhesive strength of the adhesive layer 304, if any, is too low. The other transfer film was removed from the surface of the nanofiber forest opposite to the surface of the adhesive layer 304. This can be difficult to overcome by removing the As explained above, removal of the other transfer film reorients some of the straight portions 212. However, some of the straight sections 212 may be sufficiently straight as a result of the removal of other transfer films. Therefore, the slope 404 remains close to the adhesive layer 304. can be seen in the annotated SEM micrograph in Figure 4B. Another possible mechanism is adhesion Some of the adhesion molecules from layer 304 diffuse, migrate, or otherwise move into forest 209. If the adhesive layer is directly adjacent to and in contact with the nanofibers, the nanofibers will move and thus This additional adhesion provides more adhesion than other transfer films. The nanofibers of the substrate 208 can resist alignment and reorientation forces, and thus This creates a beveled portion 404 .

[0072] In another embodiment, not shown, a nanofiber forest on adhesive layer 304 may be used. The tack may be a first nanofiber fountain when following any of the aforementioned variations of method 100. The rest is parallel (i.e., 0°) to the surface of the final substrate 312 to which the adhesive layer 304 will be attached. ) or may result in assemblies that are aligned within 10°, and may also result in the first nanoparticles A second nanofiber forest on the fiber forest is attached with adhesive layer 304. This may result in the surface of the final substrate 312 being aligned perpendicular to the surface on which it is to be formed.

[0073] Generally, the lower the adhesive strength of adhesive layer 304 and the more viscous the adhesive layer 304, the better the adhesion. As the transfer layer is removed from the assemblies 310, 314, the The nanofibers in the coating become more vertical and straight, increasing adhesive strength and reducing viscosity. As the adhesive strength and viscosity increase, the slope 404 becomes more pronounced. Further increasing the nanofibers of Forest 209 makes them less perpendicular. This allows the adhesive layer 304 to be more parallel to the surface of the final substrate 312 to which it will be attached.

[0074] Other factors also affect the degree to which the nanofibers reorient when the transfer film is removed. For example, forests consisting of shorter nanofibers generally When the transfer film is removed, it is likely to be perpendicular to the surface of the underlying final substrate 312. As the length of the nanofiber increases, the nanofiber may contain tapered sections. and / or within 10° of the surface of the adhesive layer 304 and / or the final substrate 312 The vertices remain aligned.

[0075] [Transfer film with adhesive layer and diffusion barrier] In one embodiment of the present disclosure, an adhesive is applied between the nanofiber forest and the transfer film. However, as explained above, the presence of adhesive can affect the nanofiber may affect (and in some cases may reduce) the properties of the iber forest (It has the potential to be used as a nanofiber forest while still providing the convenience of using an adhesive layer. To prevent the diffusion of adhesion molecules, embodiments of the present disclosure that include an adhesive layer also include a method for separating the adhesive and nanoparticles. The nanofiber forest may include a diffusion barrier between the nanofiber forest. The fiber can be attached to a diffusion barrier, while the diffusion barrier is Prevents the diffusion or migration of adhesion molecules. This is because the nanofiber forest of the present disclosure: As explained above, the above-mentioned method can be performed without contamination by adhesive or polymer molecules. This will enable the company to bring about benefits.

[0076] FIG. 5 illustrates an exemplary method 500 for using a diffusion barrier and adhesion layer. 6A-6H show various side views of structures corresponding to the ongoing performance of method 500. The explanation will be facilitated by referring to FIG. 5 and FIG. 6A to FIG. 6H.

[0077] In the exemplary method 500, the process involves depositing at least two stacked layers of silicon dioxide on the growth substrate 204. By the step (504) of preparing the nanofiber forests 602A, 602B This is shown in Figure 6.

[0078] The first adhesive layer 604 is a nanofiber forest stack (in this case, nanofiber The first adhesive layer 604 is applied 508 to the exposed surface of the adhesive forest 602B. , performed on the arcuate portion of the nanofiber forest (as explained above), but with different bonding strengths. Using the technique described above, a first transfer film and a second transfer film having a As a result, the nanofiber forest stack "inverts" (i.e., the straight section and its open section are reversed). It is recognized that the mouth end can be positioned so that it is on the exposed surface. The embodiment shown in FIG. 6H has the first adhesive layer 604 exposed, merely for convenience of illustration. It is shown applied to the arcuate portion of nanofiber forest 602B.

[0079] In any case, as can be seen in FIG. 6B, a portion of the first adhesive layer 604 is This penetration is due to, among other factors, the adhesive composition. The adhesive can be selected based on composition, molecular weight, viscosity, and applied pressure. Fiber Forest 602B is available in the following depth ranges D (5 μm to 100 μm, 10 μm to 200μm, 10μm~100μm, 25μm~75μm, 50μm~150μm) You can penetrate either way.

[0080] Regardless of the orientation of the nanofiber stack and the surface to which the first adhesive layer 604 is applied. The first adhesive layer 604 is heated (516) to carbonize the first adhesive layer 604. This transforms some or all of the first adhesive layer into a carbonized adhesive layer 608. ) is sufficient to convert the first adhesion layer 604 to carbon or to convert a portion of the first adhesion layer 604 to carbon. partially converts the material to carbon (e.g., some molecules of the adhesive or some of the adhesive molecules (It may remain in a non-carbonized form). This is shown in Figure 6C. The first adhesive layer 604 is in a vacuum, in an inert atmosphere (e.g., argon, nitrogen), or a combination thereof. The heating (516) can be performed within the following range (100°C to 500°C). , 200°C~450°C, 200°C~300°C, 300°C~450°C, 400 The temperature can be within any of the following ranges: 250°C to 350°C, 250°C to 500°C, 250°C to 350°C.

[0081] The method 500 includes the steps of applying a first transfer film 616 to the carbonized adhesive layer 608 (5 24), where the first transfer film 616 is attached to the second adhesive layer 620. and a release liner 624. As shown in FIG. 6D, the compressive force 616 and applied 528 to the growth substrate 204, whereby a second adhesive layer 620 is applied to the carbon substrate 204. The adhesive layer 608 is placed in contact with and adhered to the adhesive layer 608. As explained above, the compressive force The surface of the growth substrate 204 and / or the first transfer film 616 may be perpendicular and / or parallel to the surface. As noted above, a carbonized adhesive layer 608 is then applied. This second adhesive layer 620 acts as a diffusion barrier to nanofiber forest 602B. Prevents the migration of adhesion molecules.

[0082] As shown in Figure 6E, the applied compressive force (528) also compresses the stacked nanofibers. The fiber forests (in this example, forests 602A and 602B) are placed on the growth substrate 204 and and / or aligned in a common direction parallel to the surface of the first transfer film 616. As explained above, the common direction can be the direction of the growth substrate 204 and / or the first The angle can be within the range of 0° to 10° of the surface of the transfer film 616.

[0083] The growth substrate is then removed (532), as shown in Figure 6F. FILM 628 is applied to the exposed surface of the nanofiber forest stack (536). The second transfer film 628 does not contain adhesive, and may be, for example, a silicone rubber film or the aforementioned At this point, the method 500 may include: The assembly 630 shown in FIG. 6G is nanofiber-based due to the presence of the carbonized adhesive diffusion barrier 608. Fiber Forest 602A and 602B can be stored indefinitely without adhesive migration. It is possible.

[0084] Optionally, a release liner 624 exposes the second adhesive layer 620 of the first transfer film 616. The exposed second adhesive layer 620 can then be removed (540) to reveal the , can be placed on a final substrate 650 similar to the final substrate 312 described above. (544).

[0085] As shown in FIG. 6H, the second transfer film 628 also includes a nanofiber foil. The nanofiber forest can be removed (548) to expose the barrier 602A. In the "flipped" embodiment, instead of the open end shown in FIG. 6H, the arcuate portion has a second It will be appreciated that the transfer film 628 may be removed to expose the As explained above, if the bond strength between the second transfer films 628 is sufficient, The nanofibers in forests 602A, 602B are supported by the underlying surface of substrate 650. Both forests 602A and 602B can be reoriented vertically. The height of the nanotubes, the strength of the second adhesive layer 620, and the thickness of the second adhesive layer 6 20, as well as the bonding strength of the second transfer film 628. The above-described variations allow for the determination of which and to what extent forests 602A, 602B are reoriented. Also, as explained above, the nanofibers in Forest 602B It will be appreciated that some of the bars may include sloped portions.

[0086] [Nanofiber Forest] As used herein, the term "nanofiber" refers to a fiber having a diameter of less than 1 μm. It is understood that the embodiments herein are primarily made from carbon nanotubes. Graphene, micron- or nano-scale graphite fibers, are often described as and / or plates and further other compositions of nanoscale fibers such as boron nitride Any other carbon allotrope may be made dense using the techniques described below. It is recognized that the terms "nanofiber" and "carbon nanotube" as used herein " refers to single-walled carbon nanotubes and / or multi-walled ) carbon nanotubes, which are carbon atoms linked together to form a cylindrical shape. In one embodiment, the carbon nanotubes referred to herein form a 4 to 1 As used herein, the term "nanofiber sheet" or simply " "sheet" refers to the drawing process (which is incorporated herein by reference). A plurality of nanofibers are aligned by a method such as that described in International Publication No. WO 2007 / 015710. The longitudinal axis of the nanofibers in this sheet is aligned with the major surface of the sheet. perpendicular to the direction of deposition (i.e., the way the sheets were deposited, often called "forests" ( 9 and 10, respectively. 10 is explained and shown.

[0087] The dimensions of carbon nanotubes can vary greatly depending on the production method used. For example, the diameter of a carbon nanotube can be 0.4 nm to 100 nm, and its length can be 10 Carbon nanotubes can also range from 132, Very high aspect ratio with heights roughly equal to or greater than 100,000:1 (ratio of length to diameter). The properties of carbon nanotubes are highly adjustable or "tunable" Many interesting properties of carbon nanotubes have been confirmed, but their practical applications are yet to be determined. To utilize the properties of carbon nanotubes in the process, it is necessary to maintain the properties of carbon nanotubes. There is a need for scalable and controllable production methods that can be easily adapted or improved.

[0088] The unique structure of carbon nanotubes makes them suitable for specific applications. It has specific mechanical, electrical, chemical, thermal, and optical properties that make it possible to Nanotubes exhibit excellent electrical conductivity, high mechanical strength, good thermal stability, and are hydrophobic. In addition to these properties, carbon nanotubes can also exhibit useful optical properties. For example, carbon nanotubes can be used to emit or detect light at narrowly selected wavelengths. Carbon nanotubes can be used in light emitting diodes (LEDs) and photodetectors for this purpose. , which may also prove useful for photon and / or phonon transport.

[0089] According to various embodiments of the subject disclosure, nanofibers (including carbon nanotubes) (including but not limited to) a structure referred to herein as a "forest" Nanofibers as used herein can be arranged in a variety of configurations, including The carbon nanotube "forests" are aligned substantially parallel to each other on the substrate. This refers to an array of nanofibers with roughly similar dimensions. While the substrate can be of any shape, in one embodiment, the substrate The wood has a plane on which the forest is assembled. As can be seen in Figure 7, The nanofibers within the rest can be approximately equal in height and / or diameter.

[0090] The nanofiber forests disclosed herein can be relatively dense. The nanofiber forest disclosed contains at least 1 billion nanofibers / cm 2 In one particular embodiment, the nanofiber fibers described herein may have a density of Rest is 10 billion / cm 2 ~30 billion / cm 2 In other examples, the present invention may have a density of The nanofiber forest described in the book contains 90 billion nanofibers per cm 2 Order of The forest may have high or low density areas, and certain areas may have different densities. The nanofibers in the forest may also be interfiber. For example, adjacent nanofibers within a nanofiber forest may exhibit connectivity. They may be attracted to each other by van der Waals forces. The density of the fibers can be increased by applying the techniques described herein. This can be done.

[0091] Methods for producing nanofiber forests are described, for example, in the literature, which is incorporated herein by reference. This is described in WO 2007 / 015710, which is incorporated herein by reference.

[0092] Various methods have been used to prepare nanofiber precursor forests. For example, in one embodiment, nanofibers can be produced as shown schematically in FIG. In one embodiment, the catalyst is deposited on a substrate and grown in a reactor. The substrate can be placed in a furnace and then exposed to a fuel compound fed into the reactor. The substrate can also withstand temperatures greater than 1000°C and can be an inert material. may comprise stainless steel or aluminum, which may be coated with the underlying silicon (S i) placed on the wafer and other ceramic substrates (e.g., alumina, zirconia) Precursor precursors (SiO2, glass ceramic) can be used instead of Si wafers. In the case where the nanofiber is a carbon nanotube, carbon compounds such as acetylene are used. After being introduced into the reactor, the fuel compound(s) may then be may begin to accumulate on the catalyst and assemble by growing upward from the substrate, forming nanofibers. The reactor also includes a reactor in which the fuel compound(s) and carrier gas react. A gas inlet through which the spent fuel compound and carrier gas can be supplied to the reactor and discharged from the reactor. and a gas outlet through which the carrier gas can be released. Examples of carrier gases are hydrogen, argon, and helium. These gases (specifically hydrogen) also promote the growth of nanofiber forests. In addition, the nanofibers to be incorporated may be introduced into the reactor to promote Dopants may be added to the gas stream.

[0093] The process used to fabricate multi-layer nanofiber forests involves the use of a single nanofiber. A nanofiber forest is formed on the substrate, and then a first nanofiber forest is formed on the substrate. A second nanofiber forest grows in contact with the The method comprises forming a first nanofiber forest on a substrate and distributing a catalyst between the first nanofibers. The first nanofiber is deposited on the forest, and then additional fuel compounds are introduced into the reactor. A catalyst positioned on the bar forest promotes the growth of a second nanofiber forest. The applied results can be formed in many suitable ways, such as by advancing the Depending on the length, type of catalyst, and location of the catalyst, the second nanofiber layer may be It can be grown on the fiber layer or on the substrate after refreshing the catalyst with, for example, hydrogen gas. The nanofibers can either be grown directly on the substrate, and therefore under the first nanofiber layer. In any case, the second nanofiber forest grows from the first nanofiber forest. The nanofibers of the first forest can be aligned almost end-to-end, but the nanofibers of the second forest can be aligned almost end-to-end. There is an easily detectable interface between the first and second forest. A forest can contain any number of forests. For example, a multi-layer precursor forest may contain: It may contain 2, 3, 4, 5, or more forests.

[0094] [Further Consideration] The foregoing description of embodiments of the present disclosure has been presented for purposes of illustration and not exhaustive. It is not intended to limit the invention to the precise form disclosed. It will be appreciated that many modifications and variations are possible in light of the present disclosure.

[0095] The language used herein has been chosen primarily for purposes of readability and instruction. However, the terms may not be selected to describe or limit the subject matter of the present invention. Thus, the scope of the present disclosure is not determined by this Detailed Description, but rather by the present invention. It is not intended to be limited by any claims arising in an application based on the specification. Accordingly, the present disclosure is to be construed as including, but not limited to, the following claims. The disclosure is intended to be illustrative of the scope of the invention.

Claims

1. 1. A nanofiber assembly comprising: A transfer film comprising a carrier and a coating on the carrier, wherein the coating has a bond strength selected from the range of 0.1 to 1.5 N / 25 mm as measured by a 180° peel test conducted in accordance with ASTM D3330; A nanofiber forest containing multiple nanofibers the nanofibers have an arcuate portion, a straight portion, an inclined portion, and an open end of the straight portion, the inclined portion being located between the arcuate portion and the straight portion, and the open end being located at an end of the straight portion opposite the inclined portion; the plurality of nanofiber arcuate portions are disposed on the transfer film coating; A nanofiber assembly, wherein the nanofibers are perpendicular to the transfer film.

2. 10. The nanofiber assembly of claim 1, wherein the coating comprises a film selected from paraffin wax, butadiene rubber, and silicone.

3. The nanofiber assembly of claim 1 , wherein the arcuate portion is adjacent to the transfer film and the open end of the straight portion is exposed.

4. The nanofiber assembly of claim 1 , wherein the straight portion is adjacent to the transfer film and the arcuate portion is exposed.

5. 10. The nanofiber assembly of claim 1, wherein the nanofiber forest comprises two or more stacked nanofiber forests.

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