Pressure detection method, pressure detection body, and method for manufacturing a pressure detection body

Abstract

To improve pressure detection techniques.SOLUTION: A pressure detection method includes the steps of: applying pressure to a pressure detector including a substance to change in color or electrical characteristics according to the applied pressure; and analyzing the color or electrical characteristics of the pressure detector to acquire size or distribution of the pressure applied to the pressure detector.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a pressure detection method, a pressure detection body, and a method for manufacturing a pressure detection body. [Background technology]

[0002] To measure the pressure applied between contact surfaces, pressure measuring films have been developed that cause only the area where pressure is applied to change color. For example, Patent Document 1 discloses a pressure measuring film in which a microencapsulated colorant and developer are applied to a support, and by applying pressure, the microcapsules are broken, causing the colorant to be adsorbed onto the developer, and a predetermined color is produced by a chemical reaction. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] 2008-232665 [Overview of the project] [Problems that the invention aims to solve]

[0004] The pressure measuring film disclosed in Patent Document 1 cannot be reused because, once the microcapsules are destroyed, they cannot be restored to their original state. Furthermore, it is relatively expensive, and its resolution is on the order of micrometers.

[0005] This disclosure is made in view of these challenges, and its purpose is to improve pressure detection technology. [Means for solving the problem]

[0006] To solve the above problems, a pressure detection method according to one embodiment of the present disclosure comprises the steps of: applying pressure to a pressure detector containing a substance whose color or electrical properties change in response to the applied pressure; and obtaining the magnitude or distribution of the pressure applied to the pressure detector by analyzing the color or electrical properties of the pressure detector.

[0007] Another aspect of the present disclosure is a pressure detector. This pressure detector includes a substance whose color or electrical properties change in response to an applied pressure. The substance has the formula (1) [Chemical formula] (where at least one of R , 16 , ,

[0010] , , , 17 , 1 , , , ~R 16 is an organic group, and the rest are hydrogen atoms or organic groups, and R 17 is a hydrogen atom or an organic group.) and includes a fluorenylidene - acridan derivative having the structure of

[0008] Yet another aspect of the present disclosure is a method for manufacturing a pressure detector. This method includes a step of forming a film containing a substance whose color or electrical properties change in response to an applied pressure. The substance has the formula (1) [Chemical formula] (where at least one of R 1 ~R 16 is an organic group, and the rest are hydrogen atoms or organic groups, and R 17 is a hydrogen atom or an organic group.) and includes a fluorenylidene - acridan derivative having the structure of

[0009] Yet another aspect of the present disclosure is also a method for manufacturing a pressure detector. This method includes a step of dispersing a substance whose color or electrical properties change in response to an applied pressure in a dispersion medium. The substance has the formula (1) [Chemical formula] (where at least one of R 1 ~R 16 is an organic group, and the rest are hydrogen atoms or organic groups, and R 17 is a hydrogen atom or an organic group.) and includes a fluorenylidene - acridan derivative having the structure of [Advantages of the Invention]

[0010] According to the present disclosure, the pressure detection technology can be improved.

Brief Description of the Drawings

[0011] [Figure 1] It is a diagram schematically showing the molecular structure of fluorenylidene-acridan. [Figure 2] It is a diagram showing a pressure detector to which pressure is applied. [Figure 3] It is a diagram showing the visible-ultraviolet spectrogram of the pressure detector measured by the diffuse reflection method. [Figure 4] It is a diagram showing the relationship between the magnitude of the applied pressure and the reflectance at 541 nm. [Figure 5] It is a diagram showing the surface potential micrograph of the pressure detector. [Figure 6] It is a diagram showing the relationship between the magnitude of the applied pressure and the surface potential. [Figure 7] It is a diagram showing an example of the fabricated silicon mold. [Figure 8] It is a diagram showing the surface of the pressure detector after pressing a silicon mold having protrusions with a width of 2 μm. [Figure 9] It is a diagram showing the surface potential micrograph of the pressure detector after pressing a silicon mold having protrusions with a width of about 50 nm. [Figure 10] It is a diagram showing the magnitude of the frictional force applied to the pressure detector. [Figure 11] It is a diagram showing the pressure detector after applying pressure. <…>0000102

Embodiments for Carrying Out the Invention

[0012] As an embodiment of the present disclosure, a pressure detection technology using a substance whose color and electrical properties change by pressure will be described.

[0013] The pressure detection method according to this disclosure comprises the steps of applying pressure to a pressure detector containing a substance whose color or electrical properties change in response to the applied pressure, and obtaining the magnitude or distribution of the pressure applied to the pressure detector by analyzing the color or electrical properties of the pressure detector.

[0014] Unlike the pressure-measuring film disclosed in Patent Document 1, which utilizes microcapsules that are destroyed by pressure, this method uses a material whose color or electrical properties change with pressure, allowing for relatively inexpensive pressure detection. Furthermore, it improves resolution. Additionally, by using a material whose color or electrical properties can be restored to their original state, the pressure detector can be reused multiple times to detect pressure.

[0015] An example of a substance whose color and electrical properties change in response to applied pressure is fluorenylidene-acridane derivatives. Fluorenylidene-acridane derivatives have the following structure. [ka] Here, R 1 ~R 16 At least one of them is an organic group, and the rest are hydrogen atoms or organic groups, R 17 is a hydrogen atom or an organic group.

[0016] The organic group may be, for example, an alkyl group, a heteroalkyl group, an alkenyl group, a heteroalkenyl group, an alkynyl group, a heteroalkynyl group, a cycloalkyl group, a heterocycloalkyl group, an aryl group, a heteroaryl group, an alkoxy group, a carbonyl group, a carboxyl group, a cyano group, a hydroxyl group, a thiol group, an amino group, an imino group, a nitro group, a halogen, or a combination thereof.

[0017] R 17The aromatic ring group may be unsubstituted or have one or more substituents. The aromatic ring may be, for example, a benzene ring, a condensed ring such as naphthalene, anthracene, phenanthrene, or pyrene, or a heterocycle such as furan, thiophene, pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, or pyrazine. The aromatic ring may have any substituents such as alkyl groups, heteroalkyl groups, alkenyl groups, heteroalkenyl groups, alkynyl groups, heteroalkynyl groups, cycloalkyl groups, heterocycloalkyl groups, aryl groups, heteroaryl groups, alkoxy groups, carbonyl groups, carboxyl groups, cyano groups, hydroxyl groups, thiol groups, amino groups, imino groups, nitro groups, halogens, etc., or it may not have substituents.

[0018] Figure 1 schematically shows the molecular structure of fluorenylidene-acridane. Due to interference between hydrogen atoms at opposing positions in the fluorene and acridane moieties, fluorenylidene-acridane (9-(9H-fluorene-9-ylidene)-9,10-dihydroacridine) cannot adopt a planar molecular structure as a whole, but instead adopts a distorted molecular structure out of the plane. Figure 1(a) shows the folded conformation, and Figure 1(b) shows the twisted conformation. The folded fluorenylidene-acridane shown in Figure 1(a) is yellow, and the twisted fluorenylidene-acridane shown in Figure 1(b) is dark blue. The dark blue color of the twisted conformation originates from charge transfer absorption from the acridane moiety, which has electron donor properties, to the fluorene moiety, which has electron acceptor properties.

[0019] Fluorenylidene-acridan normally exists in a bent (yellow) form in solids, but changes to a twisted (blue) form upon external mechanical stimulation. This causes the solid, which was yellow, to change to a dark green color. The twisted fluorenylidene-acridan can be returned to its original bent form by exposure to solvent vapor or heating. The change between the bent and twisted forms is reversible and can be repeated many times. It has been found that not only the color but also the electrical properties differ between the bent and twisted forms. Therefore, fluorenylidene-acridan can be used as a pressure sensor for detecting pressure by utilizing these reversible changes in color and electrical properties.

[0020] The pressure detector according to the embodiments of this disclosure may have the form of a film containing a fluorenylidene-acridan derivative. The film may be manufactured using any film deposition technique, such as vacuum deposition, spin coating, or casting. To improve the resolution when detecting the distribution of applied pressure, it is preferable to use a film deposited by vacuum deposition, as will be described later.

[0021] The method for manufacturing the pressure sensor according to this embodiment may include the step of depositing a fluorenylidene-acridan derivative onto the surface of a substrate, and then converting the twisted type (blue) to a bent type (yellow).

[0022] Since fluorenylidene-acridan derivatives sublimate upon heating, they can be deposited onto substrates of any material. The deposited film is blue, and can be converted to yellow, the initial state of mechanochromism, by heating or exposure to solvent vapor. In the step of converting the fluorenylidene-acridan derivative into a bent shape, the deposited film of the fluorenylidene-acridan derivative may be placed in a sealed container and exposed to the vapor of a poor solvent such as ethanol, methanol, isopropyl alcohol, or hexane.

[0023] When pressure is applied to the film manufactured in this manner, the fluorenylidene-acridan derivative changes from yellow to green. However, the film may peel off or tear from the substrate due to mechanical stress, so to protect the film, the film on the substrate may be covered with a protective layer such as a transparent or translucent film. Alternatively, the film removed from the substrate may be laminated by sandwiching it between protective layers. If a poor solvent is used to return the green film to yellow, the film may be covered with a protective layer having pores through which the poor solvent can pass. The pores in the protective layer may be formed by laser processing or punching. The protective layer may be made of a mesh-like metal or the like. The protective layer may also have spiky (pointed) protrusions that allow more pressure to be applied to the film.

[0024] The thickness and size of the membrane may be adjusted according to the range of pressure magnitudes to be detected by the pressure sensor, the required resolution, and the purpose of pressure detection.

[0025] The pressure detector according to the embodiments of this disclosure may have the form of a dispersion in which a fluorenylidene-acridan derivative is dispersed in a dispersion medium. The dispersion medium may be any material such as fibers, paper, cloth, fabric, textile products, clothing, paper, resin, etc. The dispersion medium may be selected according to the range of pressure magnitude to be detected by the pressure detector, the required resolution, the purpose of pressure detection, etc.

[0026] The method for manufacturing a pressure detector according to this embodiment may include the step of rubbing a fluorenylidene-acridan derivative onto a substrate such as cloth or fiber. The method for manufacturing a pressure detector according to this embodiment may include the step of impregnating the substrate with a solution of the fluorenylidene-acridan derivative. The method for manufacturing a pressure detector according to this embodiment may include the step of coating the substrate with a solution of the fluorenylidene-acridan derivative. The method for manufacturing a pressure detector according to this embodiment may include the step of spraying a dispersion solution, in which the fluorenylidene-acridan derivative is dispersed in a poor solvent, onto the substrate.

[0027] The substrate may be in any shape, such as a plate, string, or wire. The substrate may have pores or irregularities on its surface that can adsorb fine particles of fluorenylidene-acridan derivative. The shape of the substrate may be selected according to the range of pressure magnitude to be detected by the pressure detector, the required resolution, and the purpose of pressure detection.

[0028] Fluorenylidene-acridan derivatives dissolve in a variety of organic solvents, forming blue solutions. This is thought to be because, in good solvents, fluorenylidene-acridan exists as monomers and adopts a more stable twisted form as monomers. On the other hand, when fluorenylidene-acridan derivatives are dispersed in poor solvents such as ethanol, methanol, and hexane, a yellow dispersion solution is formed. This is thought to be because fluorenylidene-acridan derivatives do not completely dissolve in poor solvents and adopt a more stable bent form in the solid phase. Therefore, by dispersing fluorenylidene-acridan derivatives in a poor solvent and spraying them onto a substrate, it is possible to mount them on the substrate in the bent form (yellow), which is the initial state of mechanochromism.

[0029] To uniformly mount fluorenylidene-acridan derivatives onto the surface of a substrate, it is desirable to micronize the fluorenylidene-acridan derivatives so that they are uniformly dispersed in the dispersion solution. As mentioned above, it is known that fluorenylidene-acridan derivatives do not exhibit mechanochromism even when mechanically stimulated in a poor solvent. Therefore, by pulverizing the fluorenylidene-acridan derivatives in a poor solvent to micronize them, a dispersion solution in which bent (yellow) fluorenylidene-acridan derivatives are uniformly dispersed can be prepared. The particle size of the fluorenylidene-acridan derivatives may be selected according to the range of pressure magnitudes to be detected by the pressure sensor, the required resolution, and the purpose of pressure detection.

[0030] The poor solvent may be a lower alcohol such as ethanol or methanol, or a lower hydrocarbon such as hexane. The poor solvent may be such that when the fluorenylidene-acridan derivative fine particles are dispersed, the fluorenylidene-acridan derivative exists in a bent (yellow) form rather than a twisted (blue) form. To facilitate evaporation of the poor solvent, a poor solvent with a low boiling point, such as methanol, may be used.

[0031] Fluorenylidene-acridan derivatives may be pulverized in a poor solvent using a wet grinding machine such as a bead mill or ball mill.

[0032] The step of spraying a dispersion solution of fluorenylidene-acridan derivative onto a substrate may be performed by an inkjet printer, air spray, or the like.

[0033] The method for manufacturing the pressure sensor according to this embodiment may include a step of kneading a fluorenylidene-acridan derivative into a resin.

[0034] When using a poor solvent such as a lower alcohol to return a fluorenylidene-acridan derivative mixed into a resin back to its yellow color, it is desirable to use a resin containing hydroxyl groups, such as polyvinyl alcohol or vinylon, as the base material. When a lower alcohol is added to the resin, the lower alcohol molecules penetrate the resin and come into contact with the fluorenylidene-acridan derivative molecules inside the resin. This allows the conformation of the fluorenylidene-acridan derivative molecules to change from a twisted to a bent state inside the soft resin, thus returning it to its yellow color. The type of resin may be selected according to the range of pressure magnitudes to be detected by the pressure sensor, the required resolution, and the purpose of pressure detection.

[0035] To uniformly knead the fluorenylidene-acridan derivative into the resin, it is desirable to micronize the fluorenylidene-acridan derivative. The fluorenylidene-acridan derivative may be micronized by pulverizing it in a poor solvent. The particle size of the fluorenylidene-acridan derivative may be selected according to the range of pressure magnitudes to be detected by the pressure sensor, the required resolution, and the purpose of pressure detection.

[0036] To facilitate the evaporation of the poor solvent, a poor solvent with a low boiling point, such as methanol, may be used when grinding the fluorenylidene-acridan derivative.

[0037] The method for manufacturing a pressure detector according to this embodiment may include a step of evaporating the dispersion solvent from a suspension obtained by suspending a fluorenylidene-acridan derivative and a substrate such as fibers in a dispersion solvent. The substrate may be selected according to the range of pressure magnitude to be detected by the pressure detector, the required resolution, and the purpose for which the pressure is detected.

[0038] In the pressure detection method according to the embodiments of this disclosure, the step of acquiring the magnitude or distribution of pressure may include the step of analyzing the visible ultraviolet spectroscopic spectrum or surface potential micrograph of the pressure detector.

[0039] The step of obtaining the magnitude or distribution of pressure may include a step of obtaining the magnitude of pressure applied to the pressure detector from the analysis results of the visible ultraviolet spectral spectrum or surface potential microscope image of the pressure detector, based on the correspondence between the analysis results of the previously obtained visible ultraviolet spectral spectrum or surface potential microscope image of the pressure detector and the magnitude of the pressure applied to the pressure detector.

[0040] When analyzing the visible-ultraviolet spectroscopic spectrum, the magnitude of the pressure applied to the pressure detector may be obtained based on the correspondence between the rate of decrease of the bent (yellow) absorption peak or the rate of increase of the twisted (blue) absorption peak of the fluorenylidene-acridan derivative and the magnitude of the pressure applied to the pressure detector. When analyzing surface potential microscope images, the magnitude of the pressure applied to the pressure detector may be obtained based on the correspondence between the surface potential of the pressure detector, realized by the bent and twisted potentials of the fluorenylidene-acridan derivative, and the magnitude of the pressure applied to the pressure detector.

[0041] Visible-ultraviolet spectroscopy is relatively easy to perform and can measure various forms such as powders and thin films. Surface potential microscopy has very good sensitivity and high resolution, but the forms it can measure are limited to thin films. Therefore, the analytical method for detecting pressure may be selected according to the form of the pressure detector, the range of pressure magnitudes to be detected by the pressure detector, the required resolution, and the purpose of pressure detection.

[0042] (Example 1) A film of fluorenylidene-acridan, deposited under vacuum, was subjected to pressures ranging from 0 to 450 MPa using a nanoimprint lithography apparatus. Figure 2 shows the pressure detectors to which pressure was applied. The pressure detectors shown in Figure 2 were subjected to uniform pressures of (a) 0 MPa, (b) 100 MPa, (c) 150 MPa, (d) 200 MPa, (e) 250 MPa, (f) 300 MPa, (g) 350 MPa, (h) 400 MPa, and (i) 450 MPa, applied perpendicular to the film.

[0043] Figure 3 shows the visible-ultraviolet spectral spectrum of a pressure detector measured by diffuse reflectance. The peak in the 500-600 nm (green-yellow) range decreases as the applied pressure increases. Figure 4 shows the relationship between the magnitude of the applied pressure and the reflectance at 541 nm. A decrease in reflectance due to pressure is observed from approximately 100 MPa, and in the range of approximately 200 MPa and above, the reflectance decreases almost linearly with increasing pressure. Therefore, based on the relationship in Figure 4, the magnitude of the pressure applied to the pressure detector can be obtained from the reflectance at 541 nm in the visible-ultraviolet spectral spectrum of the pressure detector.

[0044] Figure 5 shows a surface potential microscope image of the pressure sensor. The surface potential microscope image shown in Figure 5 shows the surface potential of the pressure sensor relative to the Au film. The higher the applied pressure, the higher the surface potential. Figure 6 shows the relationship between the magnitude of the applied pressure and the surface potential. An increase in surface potential due to pressure is observed from approximately 100 MPa, and in the range of approximately 150 MPa and above, the surface potential increases almost linearly with increasing pressure.

[0045] (Example 2) To measure the spatial resolution of a pressure sensor containing a vacuum-deposited fluorenylidene-acridan film, pressure was applied to the pressure sensor using a silicon mold with a surface pattern. Figure 7 shows an example of the fabricated silicon mold. Figure 7(a) shows 2 μm wide and 2 μm high protrusions formed on the surface of the silicon mold at 2 μm intervals. Figure 7(b) shows the appearance of the fabricated silicon mold. This silicon mold was pressed perpendicularly onto the pressure sensor using a nanoimprint lithography apparatus.

[0046] Figure 8 shows the surface of the pressure sensor after a silicon mold with 2 μm wide protrusions was pressed onto it. Figure 8(a) shows an atomic force microscope image of the surface of the pressure sensor. Figure 8(b) shows a surface potential microscope image of the surface of the pressure sensor. A pressure response consistent with the shape of the protrusions formed on the silicon mold was observed.

[0047] Figure 9 shows a surface potential microscope image of a pressure detector after a silicon mold with protrusions approximately 50 nm wide was pressed against it. In this case as well, a pressure response matching the shape of the protrusions formed on the silicon mold was observed. The resolution of the pressure measuring film disclosed in Patent Document 1 is approximately 125 μm × approximately 125 μm, but the pressure detector of this disclosure has been shown to have a resolution of less than 1 / 1000 of that. Since the changes in color and surface potential of the fluorenylidene-acridan derivative originate from changes in the molecular structure of each molecule, theoretically, it can be expected that a resolution of the size of a single molecule can be achieved.

[0048] (Example 3) As a pressure sensing element, a sheet was prepared by kneading fluorenylidene-acridan into polyvinyl alcohol, and a scratch test was performed by applying pressure in a direction parallel to the sheet. Figure 10 shows the magnitude of the frictional force applied to the pressure sensing elements (a) to (e). Figure 11 shows the pressure sensing elements after pressure has been applied. A change in color was observed in the pressure sensing elements (c) to (e) to which a frictional force of 0.23740 N or more was applied. Since the typical writing pressure of a person is approximately 0.3 to 0.4 N, it has been shown that the pressure sensing elements of this disclosure can detect pressures equivalent to or lower than the frictional force during writing.

[0049] Thus, when a pressure with a horizontal component is applied, the color and electrical properties of the fluorenylidene-acridan derivative can be changed at a lower pressure compared to when a vertical pressure is applied, and therefore, even lower pressures can be detected.

[0050] The present disclosure has been explained above based on examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible in combinations of their components and processing processes, and that such modifications are also within the scope of the present disclosure.

Claims

1. A step in which pressure is applied to a pressure sensor containing a substance whose color or electrical properties change in response to the applied pressure, The steps include: obtaining the magnitude or distribution of the pressure applied to the pressure detector by analyzing the color or electrical characteristics of the pressure detector; A step of restoring a substance whose color or electrical properties have changed due to the application of pressure, Equipped with, The aforementioned substance is Formula (1) 【Chemistry 1】 The fluorenylidene-acridan derivative has the structure represented by , wherein at least one of R1 to R16 is an organic group, the rest are hydrogen atoms or organic groups, and R17 is a hydrogen atom or an organic group. The aforementioned restoring step includes the step of adding a poor solvent to the substance, The poor solvent comprises at least one of ethanol, methanol, isopropyl alcohol, and hexane. Pressure detection method.

2. The step of obtaining the magnitude or distribution of the pressure includes the step of analyzing the visible ultraviolet spectroscopic spectrum or surface potential micrograph of the pressure detector. The pressure detection method according to claim 1.

3. The step of obtaining the magnitude or distribution of the pressure includes a step of obtaining the magnitude of the pressure applied to the pressure detector from the analysis results of the visible ultraviolet spectroscopic spectrum or surface potential microscope image of the pressure detector, based on the correspondence between the analysis results of the previously obtained visible ultraviolet spectroscopic spectrum or surface potential microscope image of the pressure detector and the magnitude of the pressure applied to the pressure detector. The pressure detection method according to claim 2.

4. The pressure sensing element includes a membrane containing the substance, or a dispersion of the substance in a dispersion medium. A pressure detection method according to any one of claims 1 to 3.

5. The substance contains a material whose color or electrical properties change depending on the applied pressure, The aforementioned substance is Formula (1) 【Chemistry 2】 It has a structure represented by R １ ~R １６ At least one of them is an organic group, and the rest are hydrogen atoms or organic groups, R １７ It contains a fluorenylidene-acridan derivative which is a hydrogen atom or an organic group. The substance, after its color or electrical properties change due to the application of pressure, returns to its original state when a poor solvent containing at least one of ethanol, methanol, isopropyl alcohol, and hexane is added. Pressure sensor.

6. A film containing the aforementioned substance, or a dispersion of the aforementioned substance in a dispersion medium. The pressure detection body according to claim 5.

7. The process includes the step of forming a film containing a substance whose color or electrical properties change in response to applied pressure, The aforementioned substance is Formula (1) 【Transformation 3】 It has a structure represented by R １ ~R １６ At least one of them is an organic group, and the rest are hydrogen atoms or organic groups, R １７ It contains a fluorenylidene-acridan derivative which is a hydrogen atom or an organic group. The substance, after its color or electrical properties change due to the application of pressure, returns to its original state when a poor solvent containing at least one of ethanol, methanol, isopropyl alcohol, and hexane is added. A method for manufacturing a pressure detection element.

8. The method includes the step of dispersing a substance whose color or electrical properties change in response to applied pressure in a dispersion medium, The aforementioned substance is Formula (1) 【Chemistry 4】 has a structure represented by R １ ~R １６ at least one of which is an organic group and the rest are hydrogen atoms or organic groups, and R １７ includes a fluorenylidene-acridan derivative which is a hydrogen atom or an organic group The substance, after its color or electrical properties change due to the application of pressure, returns to its original state when a poor solvent containing at least one of ethanol, methanol, isopropyl alcohol, and hexane is added. A method for manufacturing a pressure detection element.

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