Pressure-responsive structural color device and method for manufacturing pressure-responsive structural color device

Abstract

The present invention relates to a pressure-responsive structural color device and a method for manufacturing the pressure-responsive structural color device. The pressure-responsive structural color device according to the present invention comprises: a flexible substrate; and fine particles which are arranged on the flexible substrate and express a structural color. As the separation distance between the fine particles is greater than a predetermined value, the fine particles, when pressed against the flexible substrate, are entirely embedded in the interior of the flexible substrate such that the structural color weakens or disappears.

Description

Pressure-responsive structural color element and method for manufacturing the pressure-responsive structural color element

[0001] The present invention relates to a pressure-responsive structural color device and a method for manufacturing the pressure-responsive structural color device, and more particularly, to a pressure-responsive structural color device that expresses structural color in a pattern using fine particles, and in which the expression of the structural color changes by applying pressure, and a method for manufacturing the pressure-responsive structural color device.

[0002] Structural color, found in feathers of male peacocks and wings of butterflies, is created by light being reflected, scattered, or diffracted by micro- or nano-scale micro-patterned structures on the surface. Colors typically created with pigments or dyes are created when pigment molecules reflect only a specific color and absorb the rest. These are called "chemical colors," which are created by chemical components. Meanwhile, structural color is a "physical color," where the physical structure influences light to create the color.

[0003] In general, structural color is determined by the period of the micro-pattern. At this time, when the period of the micro-pattern is changed by deforming (tensioning) the substrate, a change in the structural color occurs depending on the amount of deformation. By utilizing this characteristic, a structural color element formed with a micro-pattern can be used as a structural color sensor that determines the temperature, humidity, tensile force, etc. according to the degree of deformation of the substrate by identifying the structural color when the structural color changes due to deformation of the substrate due to changes in temperature, humidity, tensile force, etc., together with a camera that detects the change in color.

[0004] Additionally, structural color components that express structural color are also used to prevent counterfeiting.

[0005] Previously, methods known to prevent counterfeiting included using holograms and using overt-covet features.

[0006] Methods utilizing the hide-and-show function utilize the characteristic of processing a specific shape, text, or logo on the surface, hiding it so that it is normally invisible (hidden), and only becoming visible through a specific external physical, chemical, or optical stimulus. For example, known methods include UV fluorescent printing, which requires exposure to ultraviolet rays to confirm the printed content; methods in which the pattern is only visible when the film is removed; and methods in which the pattern is only visible when heat is applied. In this case, it is known that the higher the difficulty of the formation (processing or printing) process of the shape, text, or logo, the higher the anti-counterfeiting performance.

[0007] However, methods utilizing holograms have the disadvantage of being susceptible to duplication and forgery. Furthermore, existing methods utilizing hide-and-seen functionality also utilize fluorescent or printed film, making them relatively susceptible to forgery.

[0008] In contrast, when structural color using nano patterns is used to prevent counterfeiting, it has the advantage of being very difficult to counterfeit because it is essential to produce regular nano structures using nano-processing technology.

[0009] Accordingly, the purpose of the present invention is to solve the above-mentioned conventional problems, and to provide a pressure-responsive structural color element that can be used as an anti-counterfeiting element by utilizing a change in structural color according to pressure, by arranging fine particles on a flexible substrate to express structural color, but having a distance between the fine particles greater than a certain value so that when the fine particles are pressed toward the flexible substrate, the entire fine particles are drawn into the flexible substrate, thereby weakening or disappearing the structural color, and a method for manufacturing the pressure-responsive structural color element.

[0010] The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011] The above object can be achieved by a pressure-responsive structural color element according to the present invention, which comprises a flexible substrate; and fine particles arranged on the flexible substrate to express structural color, wherein the distance between the fine particles is greater than a predetermined value, so that when the fine particles are pressed toward the flexible substrate, the entirety of the fine particles sink inside the flexible substrate, thereby weakening or disappearing the structural color.

[0012] Here, a first region in which the distance between the fine particles is greater than a certain value and the fine particles are entirely drawn into the flexible substrate when pressed toward the flexible substrate, thereby weakening or disappearing the structural color, and a second region in which the distance between the fine particles is less than a certain value and the fine particles are not entirely drawn into the flexible substrate when pressed toward the flexible substrate, thereby maintaining the structural color, can be distinctly formed.

[0013] Here, the distance between the centers of the fine particles in the first region and the second region is preferably the same, so that the structural colors of the first region and the second region are the same before the fine particles are pressed toward the flexible substrate.

[0014] Here, the pressure-responsive structural color element may be an anti-counterfeiting element in which the structural color of at least some area is weakened or disappears when the fine particles are pressed toward the flexible substrate.

[0015] Here, a pressure film may be further included, which is arranged on the side where the fine particles are arranged as a transparent film and presses the fine particles toward the flexible substrate with a body or tool.

[0016] Here, it is preferable that the fine particles are rigid particles.

[0017] In addition, the above object can be achieved by a method for manufacturing a pressure-responsive structural color element, which comprises the steps of: arranging fine particles to express structural color on a flexible substrate according to the present invention; and etching the fine particles so that the fine particles are spaced apart from each other, and the distance between the fine particles is greater than a predetermined value, so that when the fine particles are pressed toward the flexible substrate, they are entirely drawn into the flexible substrate, thereby weakening or disappearing the structural color.

[0018] Here, the step of etching the fine particles includes a step of etching the fine particles in a portion of the region to form a first region where the fine particles are etched and a second region where the fine particles are not etched, and when the fine particles are pressed toward the flexible substrate, the fine particles in the first region are entirely entrained into the flexible substrate, so that the structural color is weakened or disappears, and the fine particles in the second region are not entirely entrained into the flexible substrate because the distance between the fine particles is smaller than a predetermined value, so that the structural color can be maintained.

[0019] Here, the fine particles can be etched by reactive ion etching (RIE).

[0020] As described above, when the pressure-responsive structural color element of the present invention is used as an anti-counterfeiting element, it has the advantage of being difficult to counterfeit because it uses a nano-process technology with high difficulty.

[0021]

[0022] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the present invention or the composition of the invention described in the claims.

[0023] FIG. 1 illustrates two examples of arranging fine particles to express structural color on a flexible substrate, and FIG. 1 (b) illustrates a pressure-responsive structural color element according to one embodiment of the present invention.

[0024] Figure 2 is a drawing showing changes when pressurizing fine particles in Figure 1 (a).

[0025] Figure 3 is a drawing showing changes when pressurizing fine particles in Figure 1 (b).

[0026] FIG. 4 illustrates changes before and after pressurization of a pressure-responsive structural color element according to another embodiment of the present invention, and illustrates changes in structural color of an actually manufactured element.

[0027] Figure 5 is a modified example of Figure 4.

[0028] FIG. 6 illustrates a method for manufacturing a pressure-responsive structural color element according to one embodiment of the present invention.

[0029] FIG. 7 illustrates a method for manufacturing an input-responsive structural color element according to another embodiment of the present invention.

[0030] Specific details of the embodiments are included in the detailed description and drawings.

[0031] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

[0032]

[0033] Hereinafter, the present invention will be described with reference to drawings for explaining a pressure-responsive structural color element and a method for manufacturing the pressure-responsive structural color element according to embodiments of the present invention.

[0034] FIG. 1 illustrates two examples of arranging fine particles to express structural color on a flexible substrate. FIG. 1 (b) illustrates a pressure-responsive structural color element according to one embodiment of the present invention. FIG. 2 is a drawing illustrating changes when pressurizing fine particles in FIG. 1 (a), and FIG. 3 is a drawing illustrating changes when pressurizing fine particles in FIG. 1 (b).

[0035] As illustrated in FIG. 1, fine particles (110) may be arranged in a single layer on a substrate (100) to express structural color. The size of the fine particles (110) may be nano- or micro-sized particles, and in conventional structural color devices, fine particles (110) of known sizes or types that are bonded and arranged on a substrate to express structural color may be used. It is preferable that the fine particles (110) are particles of a rigid material.

[0036] The distance (a) between the centers of the fine particles (110) in Fig. 1 (a) and Fig. 1 (b) is the same. Since the structural color is determined according to the pattern period (distance between centers) of the fine particles (110), the structural colors in Fig. 1 (a) and Fig. 1 (b) are the same.

[0037] In comparison with (b) of Fig. 1, Fig. 1 (a) shows that the fine particles (110) are in close contact or proximity with each other and are in a closely packed state.

[0038] In addition, (b) of Fig. 1 etches the fine particles (110) in the densely packed state of (a) of Fig. 1, thereby reducing the size of the fine particles (110). Therefore, in (b) of Fig. 1 , the distance (a) between the centers of the fine particles (110) is the same as in (a) of Fig. 1 , but the separation distance (b) between the fine particles (110) increases, resulting in a non-closely packed state.

[0039] At this time, the substrate on which the fine particles (110) are arranged is a flexible substrate (100). For example, a polymer substrate such as an elastic (double-sided) tape or PDMS (Polydimethylsiloxane) can be used as the flexible substrate (100).

[0040] Therefore, since the substrate (100) is elastically deformable, when the fine particles (110) are pressed toward the flexible substrate (100), the fine particles (110) can be introduced into the flexible substrate (100).

[0041] At this time, a pressure film (120) is placed on the side where the fine particles (110) are arranged as a transparent film, and the pressure film (120) can be pressed with a body or a tool to press the fine particles (110) toward the flexible substrate (100). The pressure film (120) performs a protective function to prevent the fine particles (110) from being separated from the flexible substrate (100) during the pressurizing process, and at the same time, it performs an observation function to observe changes in structural color by being formed as a transparent film. Of course, the fine particles (110) can also be pressed directly without the pressure film (120).

[0042] As shown in FIGS. 2 and 3, when the fine particles (110) are pressurized, the inflow state of the fine particles (110) is different depending on the arrangement state of (a) and (b) of FIG. 1.

[0043] As illustrated in FIG. 2, in a densely packed state, when pressure is applied, temporary burial of the fine particles (110) occurs toward the flexible substrate (100), but since there is almost no gap between the fine particles (110), the fine particles (110) are not entirely drawn into the flexible substrate (100). Therefore, the pressurized film (120) does not come into contact with the flexible substrate (100) due to the fine particles (110). Therefore, the fine pattern by the fine particles (110) is maintained as is, so the structural color does not change. When the pressure is removed, the partially drawn fine particles (110) can return to their original position on the left side by elastic restoration.

[0044] As illustrated in FIG. 3, in the state of a spherical array, when pressure is applied, the fine particles (110) are drawn into the flexible substrate (100) and are sunk together with the elastic deformation of the flexible substrate (100). Therefore, the pressurized film (120) can come into contact with the flexible substrate (100). At this time, when the optical refractive index of the flexible substrate (100) and the optical refractive index of the fine particles (110) are different from each other, the structural color is weakened, and when the refractive index of the flexible substrate (100) and the optical refractive index of the fine particles (110) are the same, the structural color disappears. When the structural color is weakened, it may mean that the color is maintained but the brightness or saturation is reduced. Similarly, when the pressure is removed, the drawn fine particles (110) can return to their original position on the left by elastic restoration.

[0045] In this way, the change in structural color according to pressure may be different depending on the arrangement state of the fine particles (110).

[0046] As illustrated in (b) of FIG. 1, a pressure-responsive structural color device according to an embodiment of the present invention may be arranged such that fine particles (110) are arranged on a flexible substrate (100) to express structural color, and the distance between the fine particles (110) is greater than a certain value so that the fine particles (110) are entirely drawn into the flexible substrate (100) when pressed toward the flexible substrate (100). The distance (a) between the centers of the fine particles (110) should be a distance capable of expressing a specific structural color, and the distance (b) between the fine particles (110) should be a distance capable of causing the entire fine particles (110) to be sunk into the flexible substrate (100) by pressurization.

[0047] Therefore, the pressure-responsive structural color element according to the present invention can be used as an anti-counterfeiting element by causing the structural color to weaken or disappear when the fine particles (110) are pressed toward the flexible substrate (100).

[0048] FIG. 4 illustrates changes before and after pressurization of a pressure-responsive structural color element according to another embodiment of the present invention, and illustrates changes in structural color of an actually manufactured element, and FIG. 5 is a modified example of FIG. 4.

[0049] The following description will focus on differences from those described with reference to Figures 1 to 3.

[0050] In this embodiment, fine particles (110) are arranged in different arrangement states in the first region and the second region on the same flexible substrate (100). In the first region, structural color is expressed by the arrangement of fine particles (110), but the distance (b) between the fine particles (110) is greater than a certain value so that when the fine particles (110) are pressed toward the flexible substrate (100), the entire fine particles (110) are drawn into the flexible substrate (100), so that the structural color is weakened or disappears. That is, in the first region, fine particles (110) are arranged in a sparse arrangement state as shown in (b) of FIG. 1. In the second region, the structural color is expressed by an arrangement of fine particles (110), but the spacing (b) between the fine particles (110) is smaller than a certain value or is in contact with each other so that when the fine particles (110) are pressed toward the flexible substrate (100), the entire fine particles (110) are not sunk into the flexible substrate (100) to maintain the structural color. That is, in the second region, the fine particles (110) are arranged in a dense arrangement as shown in (a) of Fig. 1.

[0051] At this time, since the distance (a) between the centers of the fine particles (110) in the first region and the second region is the same, the structural colors of the first region and the second region may be the same before the fine particles (110) are pressed toward the flexible substrate (100). At this time, when the fine particles (110) are pressed toward the flexible substrate (100), the structural color of the first region changes by weakening or disappearing, and the structural color of the second region maintains the same color.

[0052] In Fig. 4, a second region in a dense arrangement state is formed in the center, and a first region in a sparse arrangement state is formed around the first region. At this time, the structural color of the first region and the second region is expressed in green. The color of the structural color may vary depending on the distance (a) between the centers of the fine particles (110). At this time, when the fine particles (110) are pressed toward the flexible substrate (100) using the pressurizing film (120), the entire fine particles (110) in the first region are drawn into the flexible substrate (100), causing the structural color to disappear, and only the second region in the center maintains the green structural color.

[0053] In contrast, in Fig. 5, a first region in a dense arrangement state is formed in the center, and a second region in a dense arrangement state is formed around the first region. Similarly, the structural colors of the first region and the second region are expressed in green. At this time, when the fine particles (110) are pressed toward the flexible substrate (100) using the pressurizing film (120), the entire fine particles (110) in the first region are drawn into the flexible substrate (100), so that the structural color disappears, and only the first region in the center has the structural color disappear, so that it displays a square shape in black (black tape is used as the flexible substrate (100).

[0054] As shown in FIGS. 4 and 5, by forming a first region and a second region separately, a hidden shape can be revealed through a partial change in structural color due to pressure. Using this principle, the pressure-responsive structural color element according to the present invention can be used as an anti-counterfeiting element with a hide-and-show function.

[0055] Hereinafter, a method for manufacturing a pressure-responsive structural color element according to the present invention will be described.

[0056] FIG. 6 illustrates a method for manufacturing a pressure-responsive structural color element according to one embodiment of the present invention, and FIG. 7 illustrates a method for manufacturing an input-responsive structural color element according to another embodiment of the present invention.

[0057] A method for manufacturing a pressure-responsive structural color device according to one embodiment of the present invention may include a step of arranging fine particles (110) on a flexible substrate (100) to express structural color (S210), and a step of etching the fine particles (110) so that the fine particles (110) are spaced apart from each other (S220). At this time, it is preferable to etch so that the distance between the fine particles (110) is greater than a certain value so that the entire fine particles (110) can be drawn into the flexible substrate (100) when the fine particles (110) are pressed toward the flexible substrate (100). Therefore, if the entire fine particles (110) are drawn into the flexible substrate (100) by pressure, the structural color may weaken or disappear before being drawn in. As described above, if the optical refractive index of the flexible substrate (100) and the optical refractive index of the fine particles (110) are different from each other, the structural color is weakened, and if the optical refractive index of the flexible substrate (100) and the refractive index of the fine particles (110) are the same, the structural color disappears.

[0058] According to the above manufacturing method, a pressure-responsive structural color element according to (b) of the above-described Fig. 1 can be manufactured.

[0059] To be more specific, the step (S210) of arranging fine particles (110) to express structural color on a flexible substrate (100) may be composed of a step of arranging fine particles (110) on a rigid substrate and transferring the fine particles (110) of the rigid substrate to a flexible substrate (100) having an adhesive layer formed on one side thereof.

[0060] In this embodiment, a silicon substrate, a metal substrate, a glass substrate, etc. can be used as a rigid substrate. At this time, the spacing (pattern) between the centers of the fine particles (110) allows a structural color of a specific color to be expressed. When the fine particles (110) are arranged so that they are in contact with each other, the diameter of the fine particles (110) is the spacing between the centers of the fine particles (110), so the color of the structural color can be set based on the size of the fine particles (110).

[0061] Nano- or micro-sized fine particles (110) can be arranged in a monolayer by self-assembly on a rigid substrate.

[0062] For example, in the present embodiment, a polystyrene solution (10% weight / volume, Bangs Laboratories, Inc.) having an average diameter of 780 nm is mixed with a surfactant, Triton, at a volume ratio of 400:1, and the droplets are sprayed onto the substrate, and the substrate is rotated. The surfactant delays the evaporation process while the droplets of the polystyrene solution are spinning, thereby providing more time for the polystyrene nanoparticles to self-arrange into a wide area of ​​a single layer. The type of the fine particles (110) arranged on the substrate and the method of arranging the fine particles (110) are not limited to the above-described method, and other known methods may be used.

[0063] After arranging the fine particles (110) on the rigid substrate as described above, they can be transferred to a flexible substrate (100) on which an adhesive layer is formed, so that the fine particles (110) can be arranged on the flexible substrate (100). At this time, the flexible substrate (100) may be a (double-sided) tape on which an adhesive layer is formed. Alternatively, an adhesive layer may be separately formed on a substrate made of a flexible material such as PDMS, and then the fine particles (110) arranged on the rigid substrate can be transferred to the flexible substrate (100). By the adhesive layer, the fine particles (110) can be fixed in position on the flexible substrate (100) without being detached.

[0064] Next, the fine particles (110) arranged on the flexible substrate (100) are etched to reduce the size of the fine particles (110) so that the distance between the fine particles (110) becomes greater than a certain value (S220).

[0065] In this embodiment, the size of the fine particles (110) arranged in a single layer can be reduced by using a plasma-based ion etching (RIE: Reactive Ion Etching) method.

[0066] Next, a method for manufacturing a pressure-responsive structural color element according to another embodiment of the present invention will be described with reference to FIG. 7. According to the method of FIG. 7, a pressure-responsive structural color element can be manufactured in which fine particles (110) are arranged in a sparse arrangement state and a dense arrangement state in the first region and the second region, respectively, as described with reference to FIGS. 4 and 5.

[0067] As described above, after arranging the fine particles (110) so that structural color is expressed on the flexible substrate (100) on which the adhesive layer is formed (S210), the fine particles (110) are etched, but by using a mask (M) to etch the fine particles (110) only in some areas, a first area where the fine particles (110) are etched and a second area where the fine particles are not etched can be formed separately (S220').

[0068] Therefore, since the distance (a) between the centers of the fine particles (110) in the first region and the second region are the same before the fine particles (110) are pressed toward the flexible substrate (100), the structural colors of the first region and the second region are the same. However, when the fine particles (110) are pressed toward the flexible substrate (100), only the fine particles (110) in the first region are entirely drawn into the flexible substrate (100), so that the structural color is weakened or disappears, and the fine particles (110) in the second region maintain the distance (a) between the centers of the fine particles (110), and the fine particles (110) are not entirely drawn into the flexible substrate (100), so that the structural color is maintained.

[0069]

[0070] The scope of the present invention is not limited to the embodiments described above, but can be implemented in various forms within the scope of the appended claims. Any person skilled in the art, without departing from the spirit of the invention as claimed in the claims, may make various modifications to the invention, which are deemed to fall within the scope of the claims.

Claims

1. Flexible substrate; and Contains fine particles arranged on the flexible substrate and expressing structural color, A pressure-responsive structural color element characterized in that when the distance between the fine particles is greater than a certain value and the fine particles are pressed toward the flexible substrate, the entire inside of the flexible substrate is sunk, so that the structural color is weakened or disappears.

2. In paragraph 1, A pressure-responsive structural color element characterized in that a first region in which the distance between the fine particles is greater than a certain value and the fine particles are entirely drawn into the flexible substrate when pressed toward the flexible substrate, thereby weakening or disappearing the structural color, and a second region in which the distance between the fine particles is less than a certain value and the fine particles are not entirely drawn into the flexible substrate when pressed toward the flexible substrate, thereby maintaining the structural color, are distinctly formed.

3. In paragraph 1, A pressure-responsive structural color device characterized in that the distance between the centers of the fine particles in the first region and the second region is the same, so that the structural colors of the first region and the second region are the same before the fine particles are pressed toward the flexible substrate.

4. In paragraph 1, The pressure-responsive structural color element is characterized in that the pressure-responsive structural color element is an anti-counterfeiting element in which the structural color of at least some area is weakened or disappears when the fine particles are pressed toward the flexible substrate.

5. In paragraph 1, A pressure-responsive structural color device characterized in that it further includes a pressure film arranged on the side where the fine particles are arranged as a transparent film and pressurizing the fine particles toward the flexible substrate with a body or tool.

6. In paragraph 1, A method for manufacturing a structural color element, characterized in that the above fine particles are rigid particles.

7. A step of arranging fine particles to express structural color on a flexible substrate; and A step of etching the fine particles so that the fine particles are spaced apart from each other, A method for manufacturing a pressure-responsive structural color element, characterized in that when the distance between the fine particles is greater than a certain value and the fine particles are pressed toward the flexible substrate, the entire fine particles are drawn into the flexible substrate, thereby weakening or disappearing the structural color.

8. In paragraph 7, The step of etching the above fine particles is A step of etching the fine particles for a certain area to form a first area where the fine particles are etched and a second area where the fine particles are not etched, A method for manufacturing a pressure-responsive structural color element, characterized in that when the fine particles are pressed toward the flexible substrate, the fine particles in the first region are entirely entrained inside the flexible substrate, so that the structural color is weakened or disappears, and the fine particles in the second region are not entirely entrained inside the flexible substrate because the distance between the fine particles is smaller than a certain value, so that the structural color is maintained.

9. In paragraph 7 or 8, A method for manufacturing a pressure-responsive structural color device, characterized in that the fine particles are etched by ion etching (RIE: Reactive Ion Etching).

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