WO2023214544A1

WO2023214544A1 - Stress sensor and stress sensor manufacturing method

Info

Publication number: WO2023214544A1
Application number: PCT/JP2023/016869
Authority: WO
Inventors: 鴻立張; 隆憲大原
Original assignee: 凸版印刷株式会社
Priority date: 2022-05-02
Filing date: 2023-04-28
Publication date: 2023-11-09

Abstract

Provided is a stress sensor that can detect stress and shear force, that has high detection accuracy, and that can achieve a reduction in thickness. This stress sensor comprises a first base material, a second base material, three or more detection units disposed between the first base material and the second base material, and a bonding layer that is provided to a region surrounding a detection region including the three or more detection units, and that bonds the first base material and the second base material. The area of one among the a first electrode and a second electrode is smaller than the area of the other, and is equal to the overlapping area of the first electrode and the second electrode. If the number of detection units is n, the number of detection units on an arbitrary straight line passing through the geometric center of the detection region is not less than one, and not greater than (n-1).

Description

Stress sensor and stress sensor manufacturing method

The present invention relates to a stress sensor and a method for manufacturing a stress sensor.

A conventional thin pressure sensor has, for example, a structure in which two electrodes (upper and lower) are opposed to each other, and a conductive film or an insulating layer is sandwiched between the two electrodes as a pressure-sensitive layer that senses the pressing force. For example, Patent Document 1 has a configuration in which a sensor sheet is sandwiched between a pair of electrode sheets, and changes in electrical resistance or capacitance due to changes in thickness depending on the applied load are used as pressure. A pressure sensor for detection is described. Further, Patent Document 2 discloses that a pair of electrodes and a pair of conductive layers are provided between two sheets facing each other, and pressure is detected based on a change in electrical resistance value due to a change in the contact state between the conductive layers. A pressure-sensitive sensor is described.

Additionally, in recent years, there has been an increasing demand for stress sensors that can measure not only pressing force but also shear force. For example, Patent Document 3 describes a force sensor that can detect force and moment by arranging a plurality of strain bodies using a plurality of strain gauges. Patent Document 4 discloses a pressure sensor sheet capable of detecting shear force, in which a first electrode, an insulating layer, a second electrode, and a protective layer are provided on a substrate, and the insulating layer is formed of multiple layers with different characteristics. Are listed.

Japanese Patent Application Publication No. 2020-46392 Japanese Patent Application Publication No. 2018-112405 JP2021-139626A JP2020-177028A

Pressure sensors are expected to be applied to fields such as sports, medicine, and nursing care. For example, in the medical field, technology for sensing by being implanted in living bodies is being considered. Furthermore, a pressure sensor capable of detecting shear force as described in Patent Document 4 is being considered for use in, for example, monitoring the soles of the feet of sprinters. In order to reduce the burden placed on the site where the pressure sensor is implanted and to reduce the sense of discomfort when wearing it, there is a need for pressure sensors to be made smaller and thinner. There is also a demand for improved detection accuracy of pressure sensors.

The present invention has been made with attention to these points, and an object of the present invention is to provide a stress sensor that can detect pressure and shear force, has high detection accuracy, and can be made thin.

The stress sensor according to the present invention includes a first base material, a second base material, three or more detection parts arranged between the first base material and the second base material, and three or more detection parts. and an adhesive layer that is provided in a region surrounding the detection region and that adheres the first base material and the second base material. Each of the sensing parts is provided on a first base material, and includes a first sensing part component having a first electrode and a first pressure sensitive layer in order from the first base material side, and a first sensing part component on a second base material. and a second sensing part component which is provided so as to face the second sensing part and has a second electrode and a second pressure sensitive layer in this order from the second base material side. The area of one of the first electrode and the second electrode is smaller than the area of the other, and the overlapping area of the first electrode and the second electrode is equal to the area of one of the first electrode and the second electrode, and the number of sensing parts is When is set to n, the number of detection parts existing on an arbitrary straight line passing through the geometric center of the detection area is 1 or more (n-1) or less.

The method for manufacturing a stress sensor according to the present invention includes a step of forming three or more first electrodes on a first base material, and the same number of first pressure sensitive layers as the first electrodes so as to cover each of the first electrodes. and forming three or more first sensing portion components in which the first pressure sensitive layer is laminated on the first electrode, and forming the same number of second electrodes as the first electrodes on the second base material. forming the same number of second pressure-sensitive layers as the first electrodes so as to cover each of the second electrodes, and the second pressure-sensitive layer is laminated on the second electrodes. forming the same number of second sensing part components, and placing the first base material and the second base material facing each other so that each of the first sensing part components faces each of the second sensing part components. and bonding the first base material and the second base material together via an adhesive layer provided in a region surrounding the first sensing part component and the second sensing part component. When the number of detection parts is n, the first electrode is formed so that the number of detection parts existing on an arbitrary straight line passing through the geometric center of the detection area is 1 or more (n-1) or less, and the second electrode is In the step of forming the electrodes, the second electrodes are formed so that the arrangement of all the second electrodes is a mirror image of the arrangement of all the first electrodes, and the area of one of the first and second electrodes is larger than that of the other. The first electrode and the second electrode are formed so that the overlapping area of the first electrode and the second electrode is smaller than the area of the first electrode and the second electrode is equal to the area of one of the first electrode and the second electrode.

According to the aspect of the present disclosure, it is possible to provide a stress sensor that can detect pressure and shear force, has high detection accuracy, and can be made thinner.

FIG. 1A is a schematic diagram of the stress sensor 100 according to the first embodiment. FIG. 1B is a schematic diagram of the stress sensor 100 according to the first embodiment. FIG. 2A is an exploded view of the stress sensor 100 according to the first embodiment. FIG. 2B is an exploded view of the stress sensor 100 according to the first embodiment. FIG. 3A is a schematic diagram for explaining the central detection section. FIG. 3B is a schematic diagram for explaining the central detection section. FIG. 4A is a diagram for explaining a pressure measurement method using the stress sensor 100 according to the first embodiment. FIG. 4B is a diagram for explaining a pressure measurement method using the stress sensor 100 according to the first embodiment. FIG. 5A is a diagram for explaining a shear force measurement method using the stress sensor 100 according to the first embodiment. FIG. 5B is a diagram for explaining a shear force measurement method using the stress sensor 100 according to the first embodiment. A schematic diagram showing a schematic configuration of a stress sensor 200 according to a second embodiment A schematic diagram showing a schematic configuration of a stress sensor 200 according to a second embodiment A plan view showing an example of arrangement of electrodes on the first base material A plan view showing another arrangement example of electrodes on the first base material A plan view showing a state in which a resin layer is formed on the electrode on the first base material Cross-sectional view showing a state in which a resin layer is formed on the electrode on the first base material A plan view showing an example of arrangement of electrodes on the second base material Cross-sectional view showing a state in which a resin layer is formed on the electrode on the second base material Cross-sectional view of stress sensor 200 during pressure measurement Cross-sectional view of stress sensor 200 during pressure measurement Cross-sectional view of stress sensor 200 during shear stress measurement Cross-sectional view of stress sensor 200 during shear stress measurement Explanatory diagram of a stress sensor 200 according to an embodiment Explanatory diagram of a stress sensor 200 according to an embodiment Explanatory diagram of a stress sensor 200 according to an embodiment Explanatory diagram of a stress sensor 200 according to an embodiment

Hereinafter, embodiments of the present invention will be described. The shape and number of electrodes are just an example, and are not limited to the specific examples in this description. Further, for the sake of simplicity of explanation, the drawings are drawn in a ratio different from the actual size, but this does not detract from the gist of the technology according to the present invention.

(First embodiment)
1A and 1B are schematic diagrams of the stress sensor 100 according to the first embodiment, and FIGS. 2A and 2B are exploded views of the stress sensor 100 according to the first embodiment. More specifically, FIG. 1A is a transparent plan view of the stress sensor 100, and FIG. 1B is a cross-sectional view taken along line AA' shown in FIG. 1A. Both FIGS. 2A and 2B are plan views of the surface on which the detection unit components are provided.

The stress sensor 100 includes a first base material 1a, a second base material 1b, and three detection parts arranged in a two-dimensional plane between the first base material 1a and the second base material 1b, that is, a pressing force sensor. It includes a central detection section 21 for detection, a lateral shear force detection section 22, a longitudinal shear force detection section 23, and an adhesive layer 3. The central detection part 21 is a part for detecting pressure in a direction perpendicular to the surface of the base material (in the thickness direction of the base material). The lateral shearing force detection unit 22 and the vertical shearing force detection unit 23 are parts for detecting shearing forces in the left-right direction and the vertical direction in FIG. 1A, respectively.

The central detection unit 21 is arranged at the geometric center of the detection area 2 (indicated by a broken line). The lateral shear force detection section 22 is arranged on the right side of the central detection section 21 in FIG. 1A, and the longitudinal shear force detection section 23 is arranged on the lower side in FIG. 1A. The alignment direction of the center detection section 21 and the lateral shear force detection section 22 is orthogonal to the alignment direction of the center detection section 21 and the longitudinal shear force detection section 23. From the viewpoint of miniaturization of the stress sensor 100, the lateral shear force detection section 22 and the longitudinal shear force detection section 23 are preferably arranged within a circle within a radius of, for example, 5 mm from the geometric center of the central detection section 21. . In this embodiment, the adhesive layer 3 is provided in an annular region surrounding the detection region 2 and centered on the geometric center of the central detection section 21 . The adhesive layer 3 adheres the first base material 1a and the second base material 1b to each other, and suppresses misalignment with a first sensing part component 21A and a second sensing part component 21B, which will be described later.

The central detection section 21, the lateral shear force detection section 22, and the longitudinal shear force detection section 23 are composed of first detection section components 21A, 22A, and 23A, and second detection section components 21B, 22B, and 23B, respectively. configured.

As shown in FIG. 2A, first electrodes 21a, 22a and 23a and first pressure sensitive layers 21c, 22c and 23c covering each of the first electrodes 21a, 22a and 23a are laminated on the first base material 1a. has been done. The first electrode 21a and the first pressure-sensitive layer 21c constitute a first sensing part component 21A, the first electrode 22a and the first pressure-sensitive layer 22c constitute a first sensing part component 22A, and the first electrode 23a And the first pressure sensitive layer 23c constitutes the first sensing part constituent 23A.

As shown in FIG. 2B, second electrodes 21b, 22b, and 23b, and second pressure sensitive layers 21d, 22d, and 23d covering each of the second electrodes 21b, 22b, and 23b are laminated on the second base material 1b. has been done. The second electrode 21b and the second pressure-sensitive layer 21d constitute a second sensing component 21B, the second electrode 22b and the second pressure-sensitive layer 22d constitute a second sensing component 22B, and the second electrode 23b and the second pressure-sensitive layer 23d constitute a second sensing component 23B.

3A and 3B are schematic diagrams for explaining the central detection section. More specifically, FIG. 3A is a plan view showing the configuration of the central detection section 21, and FIG. 3B is a cross-sectional view taken along the line B-B' shown in FIG. 3A. FIG. 2 is a cross-sectional view showing the configuration of a central detection section 21. FIG.

As shown in FIG. 3B, the central detection section 21 is configured with a first detection section component 21A and a second detection section component 21B arranged to face each other. As described above, the first sensing component 21A includes the first electrode 21a and the first pressure sensitive layer 21c, and the second sensing component 21B includes the second electrode 21b and the second pressure sensitive layer 21d. .

In order to enable the stress sensor 100 to operate stably, it is preferable that the first pressure sensitive layer 21c completely covers the first electrode 21a. Similarly, it is preferable that the second pressure sensitive layer 21d completely covers the second electrode 21b. Moreover, it is preferable that one of the first electrode 21a and the second electrode 21b has a larger area than the other. In the example of FIGS. 3A and 3B, the first electrode 21a has a larger area than the second electrode 21b.

The second electrode 21b only needs to be placed so as to completely overlap the first electrode 21a in plan view. The electrode overlap region Lap2 shown in FIG. 3A represents a region where the first electrode 21a and the second electrode 21b overlap in plan view.

The first electrode 21a and the second electrode 21b need to be arranged so that the area of the electrode overlap region Lap2 does not change even if shear force is input to the stress sensor 100 and shear displacement occurs. Therefore, the first electrode 21a and the second electrode 21b are arranged such that the area of the electrode overlap region Lap2 is equal to the area of the electrode with the smaller area among the first electrode 21a and the second electrode 21b. .

Furthermore, in this embodiment, the outer periphery of the second electrode 21b is arranged inside the outer periphery of the first electrode 21a. Thereby, the area of the electrode overlapping region Lap2 is equal to the area of the second electrode 2b.

The first electrode 21a and the second electrode 21b are placed in an unloaded state in the thickness direction of the base material so that the area of the electrode overlap region Lap2 does not change even if shear force is input in any direction. It is desirable that the center of the first electrode 21a and the center of the second electrode 21b be arranged so as to overlap in plan view. Furthermore, the first electrode 121a and the second electrode 121a and the second electrode are arranged so that the distance from the outer periphery of the electrode with the smaller area to the outer periphery of the electrode with the larger area is larger than the maximum value (design value) of shear deformation. Preferably, the shape and arrangement of 21b is selected.

The area of the relatively small electrode is preferably 0.005 mm ² or more and 1.5 mm ² or less, and more preferably 0.0064 mm ² or more and 1.44 mm ² or less. Further, the area of the electrode having a relatively small area is preferably one-fifth or more and two-thirds or less of the area of the electrode having a relatively large area. In other words, the area of the relatively large electrode is 1.5 times or more and 5 times or less of the area of the second electrode (the area of the electrode overlap region Lap2), which is relatively small, and the stress sensor 100 can be miniaturized and Accuracy can be improved.

The arithmetic mean roughness of the surfaces of the first electrode 21a and the second electrode 21b is preferably smaller than the arithmetic mean roughness of the surfaces of the first pressure sensitive layer 21c and the second pressure sensitive layer 21d. It is more preferable that the arithmetic mean roughness of the surfaces of the first electrode 21a and the second electrode 21b is one tenth or less of the arithmetic mean roughness of the first pressure sensitive layer 21c and the second pressure sensitive layer 21d.

Note that the shapes of the first electrode 21a and the second electrode 21b are not limited, and can be selected from, for example, rectangular, circular, triangular, etc. The first pressure sensitive layer 21c and the second pressure sensitive layer 21d may have any shape as long as they can cover the first electrode 21a and the second electrode 21b.

In FIGS. 3A and 3B, the detailed structure has been explained using the central detection section 21 as an example. Since the transverse shear force detection section 22 and the longitudinal shear force detection section 23 have the same configuration as the central detection section 21, repeated explanation will be omitted.

<Base material>
The first base material 1a and the second base material 1b are preferably flexible sheet-like members. Examples of the materials for the first base material 1a and the second base material 1b include polyester, nylon (registered trademark), polyethylene, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyamide, polymethyl methacrylate, polypropylene, and polychloride. Plastic films such as vinyl, polyvinylidene chloride, polyacrylonitrile, polyimide, polyether ether ketone, ethylene-vinyl alcohol copolymer, and cellophane, silicone rubber dimethylpolysiloxane, and processed paper such as clean paper, coated paper, and calendar paper. can be used.

Here, when considering the use of the stress sensor 100 in a living body, the first base material 1a and the second base material 1b are made of a homopolymer or copolymer such as polylactic acid, polyglycolic acid, polycaprolactone, etc. Polyester, acrylic resin, silicone, cellulose derivatives such as cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polycarbonate, cycloolefin copolymer, styrene-butadiene elastomer, etc. can be used.

When the first base material 1a and the second base material 1b are plastic films, they may be either an unstretched base material or a stretched base material. When considering mechanical strength and dimensional stability, it is advantageous to use oriented substrates, such as uniaxially oriented and biaxially oriented substrates, especially biaxially oriented substrates. Although there is no limit to the thickness of the base material, it is necessary to have a thickness that can achieve sufficient strength as a base material. The thickness of the base material is, for example, within a range of 6 μm or more and 200 μm or less. Further, the materials and thicknesses of the first base material 1a and the second base material 1b do not need to be the same.

There are no restrictions on the shapes of the first base material 1a and the second base material 1b. However, in consideration of mass production, it is advantageous for the base material to be long.

<Electrode>
A conductive material with low resistivity can be used for the first electrodes 21a, 22a, 23a and the second electrodes 21b, 22b, 23b. Each first electrode 21a, 22a, 23a and each second electrode 21b, 22b, 23b are made of, for example, Au, Pt, Ag, Cu, Ni, Cr, Rh, Pd, Zn, Co, Ru, W, Os, It is possible to use metals such as Ir, Fe, Mn, Ge, Sn, Ga, and In, or conductive metal oxides such as ITO (indium tin oxide), ZnO (zinc oxide), and SnO ₂ (tin oxide). .

The thickness of the first electrodes 21a, 22a, 23a and the second electrodes 21b, 22b, 23b is not particularly limited, but is preferably in the range of 0.01 μm or more and 10 μm or less.

The method of forming the first electrodes 21a, 22a, 23a and the second electrodes 21b, 22b, 23b is not particularly limited, and a general film forming method can be used. For example, in the case of a printing method, an inkjet printing method, a screen printing method, an offset printing method, a gravure offset printing method, and a reverse offset printing method can be used to manufacture the electrode. When using the above-described printing method, it is possible to use an electrode material mixed with a resin and made into an ink that can be applied by each printing method. Further, in the case of a vapor deposition method, a vacuum evaporation method or a sputtering method can also be used.

<Pressure sensitive layer>
The conductive film materials constituting the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d have a resistivity higher than that of the first electrodes 21a, 22a, 23a and the second electrodes 21b, 22b, 23b. Must be made of high quality material.

When the surface shapes of the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d are deformed by the input pressing force, the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21c, 22c, 23c are The contact areas with the pressure layers 21d, 22d, and 23d increase, and the resistance values between the first electrodes 21a, 22a, and 23a and the second electrodes 21b, 22b, and 23b decrease. Therefore, it is preferable to use a material that easily forms surface irregularities and is deformable. Alternatively, the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d may be formed of a material whose resistance value decreases as the thickness changes depending on the input pressing force. good. In this case, it is preferable to use a material having a piezoresistive effect whose resistivity changes with deformation. As such materials, conductive polymers such as polyethylene dioxythiophene, polyaniline, and polypyrrole, and carbon pastes using graphite and carbon nanotubes are suitably used. Furthermore, it is desirable to adjust the hardness and resistivity of the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d depending on the magnitude of the assumed stress. If the expected stress is large, choose a material with high hardness and a gentle change in resistivity; if the expected stress is small, choose a material with low hardness and a steep change in resistivity.

The first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d are provided so as to cover the first electrodes 21a, 22a, 23a and the second electrodes 21b, 22b, 23b, and have a thickness of The thickness is preferably 1 μm or more and 100 μm or less.

As a method for forming the first pressure sensitive layers 21c, 22c, 23c and the second pressure sensitive layers 21d, 22d, 23d, for example, in the case of a printing method, an inkjet printing method, a screen printing method, an offset printing method can be used. . Further, in the case of a vapor deposition method, a vacuum evaporation method, a sputtering method, a thermal chemical vapor deposition method, and a plasma chemical vapor deposition method can also be used.

<Adhesive layer>
Since the adhesive layer 3 is provided in the area surrounding the detection area 2, there is no particular requirement for resistivity. However, the thickness of the adhesive layer 3 is preferably less than or equal to the total thickness of the first sensing portion components 21A, 22A, 23A and the second sensing portion components 21B, 22B, 23B. There are no particular restrictions on the material for the adhesive layer 3, as long as it has good adhesion to the base material. For example, rubber-based, acrylic-based, silicone-based adhesives, and the like are preferably used. Further, as the adhesive layer 3, it is also possible to use double-sided tape or the like. The adhesive layer 3 only needs to be formed so as to surround all the components of the first detection part and the components of the second detection part, and may have a square annular shape or a circular annular shape, for example. The shape of the adhesive layer 3 is more preferably annular. When the adhesive layer 3 is annular, the repulsive force of the adhesive layer 3 when shear force is applied to the detection area 2 is constant regardless of the direction of the shear force, which improves the detection accuracy of shear force in all directions. can be improved.

As a method for forming the adhesive layer 3, for example, in the case of a printing method, an inkjet printing method, a screen printing method, or an offset printing method can be used.

FIGS. 4A and 4B are diagrams for explaining a pressure measurement method using the stress sensor 100 according to the first embodiment.

The central detection section 21 is configured by making a first detection section component 21A and a second detection section component 21B face each other, and a first electrode 21a and a second It can be considered that the electrode 21b is laminated with the first pressure sensitive layer 21c and the second pressure sensitive layer 21d interposed therebetween. FIG. 4A shows a state before a stress applying body (not shown) such as a finger contacts the second base material 1b, and FIG. 4B shows a state in which the stress applying body moves the second base material 1b toward the first base material 1a side. A state in which the button is pressed with a pressing force F1 is shown. When a pressing force F1 is applied to the second base material 1b, the surface shapes of the first pressure-sensitive layer 21c and the second pressure-sensitive layer 21d are deformed, as shown in FIG. The contact area with layer 21d increases. At this time, the pressure can be detected based on the change in resistance value between the first electrode 21a and the second electrode 21b in the central detection section 21.

FIGS. 5A and 5B are diagrams for explaining a shear force measurement method using the stress sensor 100 according to the first embodiment.

5A shows a state in which a pressing force F1 is applied from a stress applying body (not shown) such as a finger to the entire center detection part 21 and lateral shear force detection part 22, and FIG. The second base material 1b is pushed toward the first base material 1a side with a pressing force F1, and a shearing force F2 is further applied, using the center as a point of action. When a shearing force F2 is applied to the first base material 1a toward the right in the paper, the pressing force received by the central detection section 21 is F1, but the pressing force received by the lateral shearing force detection section 22 is F1 + ΔF. be. The shearing force F2 can be calculated based on the pressing force difference ΔF.

The stress sensor 100 according to this embodiment can be manufactured as follows.

First, after forming the first electrodes 21a to 23a on the first base material 1a, the same number of first pressure sensitive layers 21c to 23c as the first electrodes are formed so as to cover each of the first electrodes 21a to 23a, First sensing portion components 21A to 23A are formed in which first pressure sensitive layers 21c to 23c are laminated on first electrodes 21a to 23a. Further, after forming the second electrodes 21b to 23b on the second base material 1b, the same number of second pressure sensitive layers 21d to 23d as the first electrodes are formed so as to cover each of the second electrodes 21b to 23b, Second sensing portion components 21B to 23B are formed in which second pressure sensitive layers 21d to 23d are laminated on second electrodes 21b to 23b. Whichever is performed first is the formation of the first detection part components 21A to 23A on the first base material 1a or the formation of the second detection part components 21B to 23B on the second base material 1b. good. The first electrodes 21a to 23a are formed so that their geometric centers are not all located on the same straight line. The second electrodes 21b to 23b are formed so that each arrangement is a mirror image of the arrangement of the first electrodes 21a to 23a. Therefore, all the geometric centers of the second electrodes 21b to 23b are not located on the same straight line. Further, the first electrodes 21a to 23a and the second electrodes 21b to 23b have an area smaller than the other, and an overlapping area of the first electrode and the second electrode is smaller than that of the second electrode. The area is formed to be equal to the smaller one of the first electrode and the second electrode.

Next, the first base material 1a and the second base material 1b are made to face each other so that the first detection part components 21A to 23A and the second detection part components 21B to 23B face each other. Then, on either the first base material 1a or the second base material 1b, a region surrounding the first sensing portion components 21A to 23A and second sensing portion components 21B to 23B (a region surrounding the sensing region 2) is provided. The stress sensor 100 can be obtained by bonding the first base material 1a and the second base material 1b together via the provided adhesive layer 3.

In the stress sensor 100 according to the present embodiment, the central detection section 21, the lateral shear force detection section 22, and the longitudinal shear force detection section 23 are arranged so that their respective geometric centers are not aligned along the same straight line. It is located. Therefore, the shear force in the first direction can be detected based on the difference between the outputs of the central detector 21 and the lateral shear force detector 22, and the shear force in the first direction can be detected based on the difference between the outputs of the central detector 21 and the lateral shear force detector 22. Shear force in a second direction orthogonal to the first direction can be detected. Therefore, according to this embodiment, it is possible to detect pressure and shear force in any direction.

Furthermore, since the area of the second electrodes 21b to 23b is smaller than the area of the first electrodes 21a to 23a, and the area of the second electrodes 21b to 23b is equal to the electrode overlap region Lap2, when a shear force is applied, the first The overlapping area of the electrode and the second electrode does not change easily, and changes in electrical characteristics such as resistance between the first electrode and the second electrode can be detected with high accuracy.

Furthermore, by making the geometric centers of the first electrodes 21a to 23a coincide with the geometric centers of the second electrodes 21b to 23b, even if shear force is applied in any direction, the first and second electrodes Since the overlapping area can be made constant, it is possible to further improve the detection accuracy of changes in electrical characteristics between the first electrode and the second electrode.

In addition, the stress sensor 100 according to the present embodiment is configured such that the first electrode, the second electrode, the first Since the pressure sensitive layer and the second pressure sensitive layer can be formed, thinning and miniaturization are also possible.

Therefore, according to the present embodiment, it is possible to realize a stress sensor 100 that can detect pressure and shear force, has high detection accuracy, and can be made thinner.

Note that in the above embodiment, a stress sensor is described in which three detecting sections are provided between the first base material and the second base material, but the number of detecting sections may be three or more. When the total number of detection parts is n, if the detection parts are arranged so that the number of detection parts existing on any straight line passing through the geometric center of the detection area is 1 or more (n-1) or less, It is possible to detect shear forces in any direction.

However, in order to detect shear force in any direction with high precision, the geometric center of one sensing section (sensing section for pressure detection) is placed at the center of the sensing area, and the geometric center of the other sensing section is placed at the center of the sensing area. The geometric center of another detection section is placed on a first straight line (l1 in FIG. 1A) that passes through the geometric center of the detection area, and the geometric center of another detection section is placed on the first straight line that passes through the geometric center of the detection area and It is preferable to arrange it on a second straight line (l2 in FIG. 1A) perpendicular to the . Moreover, it is preferable that the geometric centers of all the detection parts are arranged on the first straight line or the second straight line. Moreover, it is more preferable that all the detection parts except for the detection part arranged at the center of the detection area are arranged so as to be rotationally symmetrical with respect to the geometric center of the detection area.

The stress sensor 100 according to the present invention described in the above embodiment is as follows.

[1] A first base material,
a second base material;
three or more detection units arranged between the first base material and the second base material;
an adhesive layer provided in a region surrounding a detection area including the three or more detection parts and bonding the first base material and the second base material,
Each of the detection units is
a first sensing part component provided on the first base material and having a first electrode and a first pressure sensitive layer in order from the first base material side;
a second sensing part component provided on the second base material so as to face the first sensing part, and having a second electrode and a second pressure sensitive layer in order from the second base material side;
The area of one of the first electrode and the second electrode is smaller than the area of the other, and the overlapping area of the first electrode and the second electrode is the area of the one of the first electrode and the second electrode. is equal to
A stress sensor, wherein the number of the detection parts existing on an arbitrary straight line passing through the geometric center of the detection area is 1 or more (n-1) or less, where n is the number of the detection parts.

[2] The stress sensor according to item 1, wherein the adhesive layer is formed in an annular shape.

[3] The three or more detection units are arranged within a circle with a radius of 5 mm from the geometric center of the detection area,
The geometric center of one of the three or more detection units overlaps the geometric center of the detection area,
The geometric center of one of the remaining detection units is located on a first straight line passing through the center of the detection area,
Item 1 or 2, wherein the geometric center of another one of the remaining detection units is located on a second straight line that passes through the center of the detection area and is orthogonal to the first straight line. 2. The stress sensor according to 2.

[4] The stress sensor according to any one of items 1 to 3, wherein the area of one of the first electrode and the second electrode is one-fifth or more and two-thirds or less of the area of the other electrode. .

[5] The stress sensor according to any one of items 1 to 3, wherein the area of one of the first electrode and the second electrode is 0.005 mm ² or more and 1.5 mm ² or less in plan view.

[6] The stress sensor according to any one of items 1 to 5, wherein the first electrode and the second electrode have a thickness of 0.01 μm or more and 10 μm or less.

[7] The stress sensor according to any one of items 1 to 6, wherein the first pressure-sensitive layer and the second pressure-sensitive layer have a thickness of 1 μm or more and 100 μm or less.

[8] The adhesive layer is formed in an annular shape,
The three or more detection parts are arranged within a circle with a radius of 5 mm from the geometric center of the detection area,
The geometric center of one of the three or more detection units overlaps the geometric center of the detection area,
The geometric center of one of the remaining detection units is located on a first straight line passing through the center of the detection area,
The geometric center of another one of the remaining detection units is located on a second straight line passing through the center of the detection area and orthogonal to the first straight line,
The area of the one of the first electrode and the second electrode is one-fifth or more and two-thirds or less of the area of the other one,
In plan view, the area of the one of the first electrode and the second electrode is 0.005 mm ² or more and 1.5 mm ² or less,
The thickness of the first electrode and the second electrode is 0.01 μm or more and 10 μm or less,
The stress sensor according to item 1, wherein the first pressure-sensitive layer and the second pressure-sensitive layer have a thickness of 1 μm or more and 100 μm or less.

[9] Forming three or more first electrodes on the first base material;
three or more first sensing units in which the same number of first pressure sensitive layers as the first electrodes are formed so as to cover each of the first electrodes, and the first pressure sensitive layers are stacked on the first electrodes; forming a composition;
forming the same number of second electrodes as the first electrodes on a second base material;
The first sensing part composition, wherein the same number of second pressure sensitive layers as the first electrodes are formed so as to cover each of the second electrodes, and the second pressure sensitive layers are laminated on the second electrodes. forming the same number of second sensing portion components;
The first base material and the second base material are opposed to each other such that each of the first detection part components and each of the second detection part components are opposed to each other, and the first detection part components and the a step of bonding the first base material and the second base material via an adhesive layer provided in a region surrounding the second sensing component,
In the step of forming the first electrode, when the number of the sensing parts is n, the number of the sensing parts existing on any straight line passing through the geometric center of the sensing area is 1 or more and (n-1) or less. forming the first electrode so that
In the step of forming the second electrode, forming the second electrode so that the arrangement of all the second electrodes is a mirror image of the arrangement of all the first electrodes,
The area of one of the first electrode and the second electrode is smaller than the area of the other, and the overlapping area of the first electrode and the second electrode is the area of the one of the first electrode and the second electrode. A method of manufacturing a stress sensor, wherein the first electrode and the second electrode are formed so as to be equal to each other.

(Second embodiment)
The present embodiment aims to provide a stress sensor capable of stable signal detection.

6A and 6B are schematic diagrams showing a schematic configuration of a stress sensor 200 according to the second embodiment. More specifically, FIG. 6A is a transparent plan view of the stress sensor 200, and FIG. 6B is a cross-sectional view taken along line CC' shown in FIG. 6A.

The stress sensor 200 includes a first base material 31, a second base material 32 facing the first base material 31, and a plurality of first laminates 11 provided between the first base material 31 and the second base material 32. and a plurality of second laminates 12 and an adhesive layer 15 that adheres the first base material 31 and the second base material 32.

The first laminate 11 is provided on one surface of the first base material 31 (the surface facing the second base material 32), and in order from the first base material 31 side, the first electrode and the top of the first electrode are provided. The first resin layer (pressure sensitive layer) is laminated on the first resin layer (pressure sensitive layer). The second laminate 12 is provided on one surface of the second base material 32 (the surface facing the first base material 31), and in order from the second base material 32 side, the second electrode and the top of the second electrode are provided. The second resin layer (pressure sensitive layer) is laminated on the second resin layer (pressure sensitive layer). The same number of first laminates 11 and second laminates 12 are provided, and are arranged so as to face each other between the first base material 31 and the second base material 32. The opposing resin layer of the first laminate 11 and the resin layer of the second laminate 12 are in contact with each other in a state where no external force is applied to the stress sensor 200.

The adhesive layer 15 is provided in a region surrounding all the first laminates 11 and second laminates 12, and adheres the first base material 31 and the second base material 32. The adhesive layer 15 maintains the positional relationship between the first laminate 11 and the second laminate 12 facing each other. In this embodiment, the adhesive layer 15 is provided in an annular region in a plan view, and the inside of the adhesive layer 15 (the part surrounded by the inner peripheral edge of the adhesive layer 15) is the area where the stress sensor 200 receives pressure and shear. This is a detection area where stress (shear stress) can be detected. Although the shape of the adhesive layer 15 is not particularly limited, it is preferably annular because it is equidistant from the center of the electrode 33. The area surrounded by the adhesive layer 15 becomes a detection area (sensing area) where the stress sensor 200 can detect pressure and stress, but in order to reduce the size of the stress sensor 200, the inner diameter of the adhesive layer is set to 10 mm or less. It is preferable that there be.

Although the material of the adhesive layer 15 is not particularly limited, it is preferable to use a material with high adhesive strength in order to prevent damage due to pressure or shear force. The adhesive force of the adhesive layer 15 in the pressure direction is preferably 5 N/25 mm width or more, and the adhesive force of the adhesive layer 15 in the shear direction is preferably 80 N/cm ² or more. The stress sensor 200 may be fixed using an adhesive or the like during use. If the adhesive force of the adhesive layer 15 is weak, the stress sensor 200 may be damaged by the bending stress applied to the stress sensor 200 when the fixed stress sensor 200 is removed. If the adhesive force of the adhesive layer 15 in the pressure direction is 5 N/25 mm width or more, damage when the fixed stress sensor 200 is removed by hand is suppressed. The same holds true for the adhesive force in the shear direction, and when the object is removed from the measurement object, the shear direction component of the bending stress increases; however, if the adhesive force of the adhesive layer 15 in the shear direction is 80 N/cm ² or more, damage during removal can be prevented. It can be suppressed. Since the actual adhesive force changes depending on the width of the adhesive layer 15, it is necessary to determine the width so that it exceeds the force applied in the shear direction when the fixed stress sensor 200 is removed, and so that the stress sensor 200 does not become too large. There is. For example, if the adhesive layer 15 is installed at a distance of about 0.85 cm radius from the center of the load, the expected shear force is 5 N, and the shear adhesive force of the adhesive layer 15 is 80 N/ ^cm2 , the shear adhesive force exceeds 5 N. The width is approximately 0.25 mm. Assuming that a large force is momentarily applied, if the width of the adhesive layer 15 is set to 1 mm, it can withstand a shearing force of up to 20N.

Hereinafter, the details of the configuration of the stress sensor 200 will be explained. In the following description, the first electrode and first resin layer on the first base material 31 and the second electrode and second resin layer on the second base material 32 are simply referred to as "electrode" and "resin layer." .

FIG. 7 is a plan view showing an example of arrangement of electrodes on the first base material.

In the example shown in FIG. 7, an electrode 33 for pressure detection and

electrodes

34 and 35 for shear stress detection are formed on one surface of the first base material 31. Since the electrodes 33 to 35 need to be formed with the same area, it is preferable that they have the same shape. In the example of FIG. 7, all the electrodes are square, but other shapes such as rectangle, circle, or ellipse may be used. Furthermore, wiring (common wiring) connecting the electrodes 33 to 35 is formed on the first base material 31, as shown by thick solid lines in FIG. The wiring can be formed in the same process as the electrode.

The electrode 33 is placed at the center of the detection area where the stress sensor 200 detects pressure and shear stress (the area where the stress sensor 200 receives load).

Electrodes

34 and 35 are placed the same distance apart from electrode 33. When one direction in the surface direction of the first base material 31 is defined as the X direction, and a direction orthogonal to the X direction is defined as the Y direction, the

electrodes

33 and 34 are arranged so as to be aligned in the X direction, and the

electrodes

33 and 35 are They are arranged so as to be aligned in the Y direction.

In the example shown in FIG. 7,

electrodes

34 and 35 are arranged, one each in the X direction and the Y direction, with the electrode 33 at the center, but this is the minimum configuration for detecting pressure and shear stress. .

FIG. 8 is a plan view showing another arrangement example of electrodes on the first base material 31.

In the example shown in FIG. 8, on one side of the first base material 31, an electrode 33 for pressure detection,

electrodes

34a and 34b for detecting shear stress in the X direction, and an electrode 35a for detecting shear stress in the Y direction are provided. and 35b are formed. The

electrodes

34a and 34b are arranged symmetrically with respect to the electrode 33, and the

electrodes

35a and 35b are arranged symmetrically with respect to the electrode 33. When the electrodes are arranged as shown in Figure 8, the shear stress in each of the X and Y directions can be detected based on the difference between the measured values of two electrodes lined up in each direction, which increases the measurement accuracy of shear stress. can be improved. When pressure is applied to the area centered on electrode 33 (but no force in the shear direction is applied), pressure is applied equally to each of

electrodes

33, 34a, 34b, 35a and 35b. From this state, for example, if a shearing force is applied in the positive direction of the X direction (toward the electrode 34a), the equal pressure balance will be disrupted, and a relatively large force will be applied to the electrode 34a, which will be applied to the electrode 34b. Power decreases. Since a difference occurs between the values detected by the

electrodes

34a and 34b, shear stress can be detected based on this difference.

Wiring connected to each electrode is formed on the first base material 31, as shown by thick solid lines in FIGS. 6A, 7, and 8. The wiring can be formed in the same process as the electrode.

FIGS. 9A and 9B are diagrams showing a state in which a resin layer is formed on the electrode on the first base material. More specifically, FIG. 9A is a plan view, and FIG. 9B is a cross-sectional view taken along line DD' shown in FIG. 9A.

As shown in FIGS. 9A and 9B, resin layers 6a to 6c are laminated to cover the electrodes 33 to 35 on the first base material 31.

The resin layers 6a to 6c serve as pressure sensitive layers.

As shown in FIG. 9A, the resin layers 6a to 6c are formed so as to overlap the entire formation area of the electrodes 33 to 35 in plan view, and completely cover each of the electrodes 33 to 35. However, it is preferable that the resin layers 6a to 6c are separated from each other. When the resin layers 6a to 6c come into contact, noise is generated and detection accuracy deteriorates.

Note that in the case of arranging the electrodes as shown in FIG. 8, resin layers are similarly laminated corresponding to each electrode.

FIG. 10 is a plan view showing an example of arrangement of electrodes on the second base material. The electrode arrangement in FIG. 10 corresponds to the electrode arrangement in FIG.

In the example shown in FIG. 10, an electrode 8 for pressure detection and

electrodes

9 and 10 for shear stress detection are formed on one side of the second base material 32. The arrangement of the electrodes 8-10 on the second base material 32 is a mirror image of the arrangement of the electrodes 33-35 shown in FIG.

Wiring connecting each of the electrodes 8 to 10 is formed on the second base material 32, as shown by thick solid lines in FIG. The wiring can be formed in the same process as the electrode.

FIG. 11 is a cross-sectional view showing a resin layer formed on the electrode on the second base material.

As shown in FIG. 11, resin layers 7a and 7b are laminated to cover the

electrodes

8 and 9 on the second base material 32.

Similar to the resin layers 6a to 6c, the resin layers 7a and 7b are formed so as to overlap the entire formation area of the

electrodes

8 and 9 in plan view, and completely cover each of the

electrodes

8 and 9. The resin layers 7a and 7b are preferably formed to have the same size as the resin layers 6a and 6b in plan view. Furthermore, in order to reduce noise, the resin layers 7a and 7b are preferably separated from each other.

Note that the resin layer provided on the electrode 10, which is not shown in FIG. 11, is also formed in the same manner as the resin layers 7a and 7b.

A flexible material is used for the first base material 31 and the second base material 32. As these base materials, for example, plastic films such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide, and paper can be used. The material of the first base material 31 can be selected as appropriate depending on the type of ink used when forming by printing, the conditions for forming electrodes when forming by photolithography, the use of the stress sensor 200, and the like. Among these, polyimide is suitable as a material that is heat resistant and strong enough to withstand the formation of slits, which will be described later. Furthermore, the first base material 31 and the second base material 32 may be made of different materials or have different thicknesses.

The electrode can be formed using a known printing method such as screen printing or gravure offset printing. It may be formed by etching a plated or sputtered film. In the present invention, after a laminate is formed by laminating a resin layer serving as a pressure-sensitive layer on an electrode, the first laminate 11 on the first base material 31 and the second laminate on the second base material 32 are formed. The laminated body 12 is made to face each other. Further, it is preferable to form alignment marks on the first base material 31 and the second base material 32. The shape and size of the alignment mark are not particularly limited.

The electrode is made of a conductive material. It is common to use a paste made by mixing noble metal powder of several micrometers to several tens of nanometers with thermosetting resin, but the conductive material may also be carbon or aluminum powder, or an alloy or mixture. good. The lower the resistance value of the electrode, the better the detection accuracy of the resistance value of the pressure sensitive layer, so it is preferable that the volume resistivity after formation is 5×10 ⁻⁵ Ωcm or less. Silver paste is suitable as the material for forming the electrodes, since it satisfies these conditions and also takes into consideration price and oxidation resistance. Further, in order to protect the wiring (lead) connected to the electrode from scratches and moisture during the manufacturing process and during use, the wiring may be protected by applying an insulating material.

Since the stress sensor 200 according to this embodiment detects pressure and shear stress based on changes in resistance between opposing electrodes, the resin layer is formed of a conductive material. However, the resin used for the electrodes is a material that has conductivity but has a higher resistivity than the electrodes. The resistivity of the resin forming the resin layer is preferably in the range of 0.05 to 1000 Ω·cm. If the resistivity is too low, there will be no electrical difference from the electrodes, making it difficult to detect signal changes when a load is applied. On the other hand, if the resistivity is too large, noise is likely to be added to the detection signal, making it difficult to detect signal changes due to noise. The resistivity is more preferably in the range of 5 to 500 Ω·cm. Specifically, conductive polymers such as polyethylene dioxythiophene, polyaniline, and polypyrrole, carbon pastes using graphite and carbon nanotubes, and materials whose resistivity is adjusted by mixing these with modifiers such as medium are used. I can do it.

The resin layer can be formed using a known printing method such as screen printing or a known coating method such as spray coating, but in order to form it limitedly in the area covering the electrode, it can be formed by one printing. Formation by a printing method is preferable.

In the stress sensor 200 according to this embodiment, a plurality of electrodes and a plurality of resin layers are laminated in this order on a first base material 31 to form a plurality of first laminates 11, and a second base material is laminated in a separate process. 32, a plurality of electrodes and a plurality of resin layers are laminated in this order to form a plurality of second laminates 12, and with the first laminate 11 and second laminate 12 facing each other, the first base It can be produced by bonding the material 31 and the second base material 32 together with the adhesive layer 15 interposed therebetween. The adhesive layer 15 may be formed by printing an adhesive in a predetermined pattern, or it may be formed by punching double-sided tape with a Pinnacle (registered trademark) blade or the like and pasting it at the position where the adhesive layer 15 is to be formed. It's okay. Double-sided tape is preferably used when it is desired not to apply unnecessary heat load to the base material or when it is desired to avoid uneven adhesive strength due to printing variations.

Next, detection of pressure and shear stress in the stress sensor 200 according to the present embodiment will be described.

12A and 12B are cross-sectional views of the stress sensor 200 during pressure measurement.

The electrode 33 on the first base material 31 and the electrode 8 on the second base material 32 are connected via a pair of

resin layers

6a and 7a. When there is no load in the pressure direction, the electrical resistance value between the electrode 33 and the electrode 8 is large because the contact area between the resin layers 6a and 7a is small (see FIG. 12A). By applying pressure, the contact area between

resin layers

6a and 7a increases (see FIG. 12B). When the contact area increases, the number of conductive paths between the upper and

lower electrodes

33 and 8 increases, and therefore the electrical resistance value decreases. Therefore, pressure can be detected based on the electrical resistance value between

electrodes

33 and 8.

13A and 13B are cross-sectional views of the stress sensor 200 during shear stress measurement.

First, when a force is applied to the detection area of the stress sensor 200 in a downward direction in the plane of the paper, which does not include a component in the shear direction, as shown in FIG. 13A, the forces applied to the

electrodes

33 and 34 are equal; The resistance value between

electrodes

8 and 9 becomes equal to the resistance value between

electrodes

34 and 9.

Next, from the state of FIG. 13A, if a shearing force is applied to the left in the paper without changing the magnitude of the force downward in the paper, the pressure applied to the electrode 33 does not change, but the balance of the load changes. As a result, the pressure applied to the electrode 34 is reduced. Therefore, in the state shown in FIG. 13B, compared to the state shown in FIG. 13A, the resistance value between

electrodes

33 and 8 does not change, and the resistance value between

electrodes

34 and 9 increases. This change in resistance value between the

electrodes

34 and 9 is detected as shear stress.

In this way, the stress sensor 200 according to the present embodiment utilizes the fact that when shear force is input, the force (component in the direction perpendicular to the base material) applied to the electrode for shear stress detection increases or decreases. Then, the direction and magnitude of the input shear force are detected. By obtaining the relationship between the pressure and shear force and the resistance value between each set of electrodes as a calibration curve in advance, the measured resistance value can be subsequently converted into pressure and shear stress.

Hereinafter, the details of the dimensions of each part will be explained with reference to the schematic diagram shown in FIG. 6B.

It is preferable that either one of the first electrode on the first base material 31 and the second electrode on the second base material 32 be formed larger than the other in plan view. In this embodiment, the first electrode on the first base material 31 is formed larger than the second electrode on the second base material 32. At the end of the manufacturing process of the stress sensor 200, the first laminate 11 and the second laminate 12 are aligned, facing each other, and fixed with the adhesive layer 15. If one of the first electrode and the second electrode is formed larger than the other, even if the alignment is misaligned in the final process, the area where the first electrode and the second electrode overlap (overlapping area) can be secured. can.

Furthermore, it is preferable that the overlapping area of the first electrode and the second electrode for shear stress detection be equal to the overlapping area of the first electrode and the second electrode for pressure detection. With this configuration, when only pressure is applied, the output from the pressure detection electrode and the output from the shear stress detection electrode become equal. Thereby, when a force in the shear direction is applied, a change in output due to a change in the force applied to the electrode for detecting shear stress can be understood as a change due to pure shear force. Furthermore, the direction in which shear force is applied can be distinguished by decreasing/increasing the resistance value of the electrode for detecting shear stress.

This will be explained with reference to FIG. 6B. Let d1 be the sum of the height d11 of the first laminate 11 and the height d12 of the second laminate 12, and let d2 be the thickness of the adhesive layer 15. In the stress sensor 200 according to this embodiment, the ratio d1/d2 is preferably 1.1 or more and 5.0 or less. When the ratio d1/d2 is less than 1.1, the contact between the first laminate 11 and the second laminate 12 becomes weak, and the signal output from each pair of the first laminate 11 and the second laminate 12 deteriorates. . When the ratio d1/d2 is larger than 5.0, the contact between the first laminate 11 and the second laminate 12 becomes excessive, and the first laminate 11 and the second laminate 12 follow the input pressure or shear force. Detection accuracy deteriorates. Condition is unstable when no load is applied. The ratio d1/d2 is more preferably 1.4 or more and 4.1 or less, and in this case, the detected value of shear force is more stable. In addition, as d1, the minimum value of the sum of the thicknesses of the plurality of sets of the first laminate 11 and the second laminate 12 may be adopted, and as d2, the minimum value of the sum of the thicknesses of the first base material 31 and the second base material 32 may be adopted. The maximum value between them may be adopted.

Furthermore, the shortest distance from the first laminate 11 to the adhesive layer 15 in the surface direction of the first base material 31 and the shortest distance from the second laminate 12 to the adhesive layer 15 in the surface direction of the second base material 32 are also determined. Let the minimum value be d3. In the stress sensor 200 according to this embodiment, the value d3 is preferably 0.75 to 3.75 mm. When the value d3 is less than 0.75 mm, the first laminate 11 and the second laminate 12 approach the adhesive layer 15, so the influence of the adhesive layer 15 increases, and the first laminate 11 and the second laminate 12 movement becomes worse, and detection accuracy deteriorates. When the value d3 exceeds 3.75 mm, the contact position between the first laminate 11 and the second laminate 12 tends to shift, and the output value becomes unstable, regardless of the value of the ratio d1/d2.

By controlling d1 to d3 so as to satisfy the above conditions, the contact state between the first laminate 11 and the second laminate 12 is stabilized, and the input pressure or shear force is applied to the first laminate 11 and the second laminate 12. The two-layered body 12 can be made to follow each other, and a stable output signal can be obtained. The above ranges of d1/d2 and d3 are particularly suitable for the stress sensor 200 in which the inner diameter of the adhesive layer is 10 mm or less, and contribute to realizing the stress sensor 200 that is small and has excellent detection accuracy.

The stress sensor according to the present invention described in the above embodiment is as follows.

[1] A stress sensor,
a first base material;
a plurality of first laminates provided on one side of the first base material;
a second base material facing the one surface of the first base material;
a plurality of second laminates provided on a surface of the second base material facing the first base material and facing each of the first laminates;
an adhesive layer that is provided to surround the first laminate and the second laminate and adheres opposing surfaces of the first base material and the second base material;
Each of the first laminates has a first electrode and a first resin layer in order from the first base material side,
Each of the second laminates has a second electrode and a second resin layer in order from the second base material side,
The ratio d1/d2 of the sum d1 of the height of the first laminate and the height of the second laminate to the thickness d2 of the adhesive layer is 1.1 to 5.0,
The shortest distance from the outer periphery of the first laminate to the adhesive layer in the plane direction of the first base material, and from the outer periphery of the second laminate to the adhesive layer in the plane direction of the second base material. A stress sensor in which the minimum value d3 of the shortest distance is 0.75 to 3.75 mm.

[2] The pressure is detected based on the electrical resistance value between the first electrode and the second electrode, which changes depending on the contact area between the first resin layer and the second resin layer, according to item 1. Stress sensor.

[3] An electrical resistance value detected using one set of the first laminate and the second laminate and another set of the first laminate and the second laminate. The stress sensor according to item 1 or 2, which detects shear stress based on a difference from an electrical resistance value.

Examples 1A to 11A that specifically implement the first embodiment will be described below.

<Example 1A>
As Example 1A, a stress sensor was manufactured in which three detection parts were arranged in a detection area and an adhesive layer was provided along a square surrounding the detection area. The three sensing parts were placed at arbitrary positions that were not aligned on the same straight line within a circle with a radius of 10 mm from the geometric center of the sensing area (however, as shown in Figure 1A, the pressure sensing part was at the center, (Excluding arrangements where the directional shear force detection unit and the longitudinal shear force detection unit are located in orthogonal directions). The overlapping area of the first electrode and the second electrode in each detection part was 4 mm ² .

Specifically, a polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form three first sensing portion components, and then a square annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form three second sensing portion components. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

The electrode area of the second electrode of the three detection parts was 4 mm ² , and the electrode area of the first electrode was 25 mm ² . The thickness of each electrode was 20 μm, and the thickness of each pressure sensitive layer was 200 μm.

As described above, the stress sensor of Example 1A was produced.

<Example 2A>
As Example 2A, a stress sensor was manufactured in which three detection parts were arranged in a detection area and an adhesive layer was provided in an annular region surrounding the detection area. The three sensing parts were placed at arbitrary positions that were not aligned on the same straight line within a circle with a radius of 10 mm from the geometric center of the sensing area (however, as shown in Figure 1A, the pressure sensing part was at the center, (Excluding arrangements where the directional shear force detection unit and the longitudinal shear force detection unit are located in orthogonal directions). The overlapping area of the first electrode and the second electrode in each detection part was 4 mm ² .

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form three first sensing portion components, and then an annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form three second sensing portion components. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

As described above, the stress sensor of Example 2A was produced.

<Example 3A>
As Example 3A, a stress sensor was manufactured in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 2 ^mm2 .

The electrode area of the second electrode of the three detection parts was 2 mm ² , and the electrode area of the first electrode was 12.5 mm ² . The thickness of each electrode was 20 μm, and the thickness of each pressure sensitive layer was 200 μm.

As described above, the stress sensor of Example 3A was produced.

<Example 4A>
As Example 4A, a stress sensor was produced in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 2 ^mm2 .

The electrode area of the second electrode of the three detection parts was 2 mm ² , and the electrode area of the first electrode was 8 mm ² . The thickness of each electrode was 20 μm, and the thickness of each pressure sensitive layer was 150 μm.

As described above, the stress sensor of Example 4A was produced.

<Example 5A>
As Example 5A, a stress sensor was manufactured in which three detection parts were arranged in the detection area as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection area. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1 mm ² .

The electrode area of the second electrode of the three detection parts was 1 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 1 μm, and the thickness of each pressure-sensitive layer was 100 μm.

As described above, the stress sensor of Example 5A was produced.

<Example 6A>
As Example 6A, a stress sensor was produced in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1 mm ² .

The electrode area of the second electrode of the three detection parts was 1 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 0.1 μm, and the thickness of each pressure-sensitive layer was 100 μm.

As described above, the stress sensor of Example 6A was produced.

<Example 7A>
As Example 7A, a stress sensor was manufactured in which three detection parts were arranged in the detection area as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection area. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1 mm ² .

The electrode area of the second electrode of the three detection parts was 1 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 0.1 μm, and the thickness of each pressure-sensitive layer was 10 μm.

As described above, the stress sensor of Example 7A was produced.

<Example 8A>
As Example 8A, a stress sensor was manufactured in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1.44 mm ² .

The electrode area of the second electrode of the three detection parts was 1.44 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 10 μm, and the thickness of each pressure sensitive layer was 50 μm.

As described above, the stress sensor of Example 8A was produced.

<Example 9A>
As Example 9A, a stress sensor was manufactured in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1 mm ² .

The electrode area of the second electrode of the three detection parts was 1 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 1 μm, and the thickness of each pressure-sensitive layer was 50 μm.

As described above, the stress sensor of Example 9A was produced.

<Example 10A>
As Example 10A,
A stress sensor was manufactured in which three detection parts were arranged in the detection region as shown in FIG. 1A, and an adhesive layer was provided in an annular region surrounding the detection region. The three detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area in orthogonal directions. The electrode overlapping area of each detection part was 1 mm ² .

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form three first sensing portion components, and then an annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form three second sensing portion components. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. Specifically, electrodes were formed using a gravure offset printing method, and a pressure sensitive layer was formed using a screen printing method. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

As described above, the stress sensor of Example 10A was produced.

<Example 11A>
As Example 11A, a stress sensor was manufactured in which five detection parts were arranged in a detection region and an adhesive layer was provided in an annular region surrounding the detection region. The five detection units were arranged in a circle with a radius of 5 mm from the geometric center of the detection area, with one detection unit as the center, and the remaining four detection units in vertical and horizontal directions (crosswise). In other words, in the stress sensor of Example 11A, two transverse shear force detection parts and two longitudinal shear force detection parts are arranged fourfold symmetrically around the pressure detection detection part shown in FIG. 1A. be. The electrode overlapping area of each detection part was 1 mm ² .

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form five first sensing portion components, and then an annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form five second sensing portion components. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

The electrode area of the second electrode of the five detection parts was 1 mm ² , and the electrode area of the first electrode was 4 mm ² . The thickness of each electrode was 0.1 μm, and the thickness of each pressure-sensitive layer was 10 μm.

As described above, the stress sensor of Example 11A was produced.

<Comparative example 1A>
As Comparative Example 1A, a stress sensor was manufactured in which one detection part was arranged in the detection area and an adhesive layer was provided along a square surrounding the detection area. One detection unit was placed at the geometric center of a detection area with a radius of 10 mm. The overlapping area of the electrodes in the detection part was 4 mm ² .

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form one first sensing component, and then a square annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were laminated on one side of the second base material to form one second sensing component. Finally, the first base material and the second base material were bonded together so that the first sensing part component and the second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

The electrode area of the second electrode of one detection unit was 4 mm ² , and the electrode area of the first electrode was 25 mm ² . The thickness of each electrode was 20 μm, and the thickness of each pressure sensitive layer was 200 μm.

As described above, a stress sensor of Comparative Example 1A was produced.

<Comparative example 2A>
As Comparative Example 2A, a stress sensor was manufactured in which three detection parts were arranged in the detection area and an adhesive layer was provided along a square surrounding the detection area. The three detection parts were arranged in a straight line in the diametrical direction within a detection area with a radius of 10 mm. The electrode overlapping area of each detection part was 4 ^mm2 .

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer are sequentially laminated on one side of a first base material to form three first sensing portion components in a straight line, and then a square annular adhesive is formed. formed a layer. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form three second sensing portion components in a straight line. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

As described above, a stress sensor of Comparative Example 2A was produced.

<Comparative example 3A>
As Comparative Example 3A, a stress sensor was manufactured in which three detection parts were arranged in the detection area and an adhesive layer was provided along a square surrounding the detection area. The three sensing parts were placed at arbitrary positions that were not aligned on the same straight line within a circle with a radius of 10 mm from the geometric center of the sensing area (however, as shown in Figure 1A, the pressure sensing part was at the center, (Excluding arrangements where the directional shear force detection unit and the longitudinal shear force detection unit are located in orthogonal directions). The electrode overlapping area of each detection part was 4 ^mm2 . However, the electrode area ratio between the first electrode and the second electrode is 1.

A polyimide film with a thickness of 25 μm was used as the first base material and the second base material. First, a first electrode and a first pressure-sensitive layer were sequentially laminated on one side of a first base material to form three first sensing portion components, and then a square annular adhesive layer was formed. Subsequently, a second electrode and a second pressure-sensitive layer were sequentially laminated on one side of the second base material to form three second sensing portion components. Finally, the first base material and the second base material were bonded together so that each first sensing part component and each second sensing part component faced each other. The electrodes were formed by gravure offset printing using silver ink, and the pressure sensitive layer was formed by screen printing using conductive ink containing carbon. The adhesive layer was formed using double-sided tape.

The electrode area of the first electrode and the electrode area of the second electrode of the three detection units were both 4 mm ² . The thickness of each electrode was 20 μm, and the thickness of each pressure sensitive layer was 200 μm.

As described above, a stress sensor of Comparative Example 3A was produced.

The configuration of each stress sensor is shown in Table 1. The electrode area ratio shown in Table 1 is the value obtained by dividing the area of the smaller second electrode by the area of the larger first electrode.

<Evaluation>
Characteristic evaluations were performed for each of the manufactured stress sensors of Examples 1A to 11A and Comparative Examples 1A to 3A.

[Press force detection characteristics]
The stress sensor of each example and comparative example is connected to an LCR meter, and the voltage when pressing with a finger from above the stress sensor with a 5V AC voltage applied between the lower electrode and the upper electrode of each sensing layer. The change in value was measured and the pressing force detection characteristics were evaluated. The criteria for determining the pressing force detection characteristics are as follows.
○ (Good): When the detected voltage value monotonically increases or decreases with respect to the pressing force. △ (Generally good): When the detected voltage value changes with the pressing force, but it does not increase or decrease monotonically. × (Poor): When the change in the detected voltage value is affected by the shear force in response to the pressing force

[Shear force detection characteristics]
When the stress sensors of each example and comparative example were connected to an LCR meter and a 5V AC voltage was applied between the lower electrode and the upper electrode of each sensing layer, the stress sensor was stroked with a finger from above. The change in voltage value was measured and the shear force detection characteristics were evaluated. The criteria for determining shear force detection characteristics are as follows.
○ (good): When the detected voltage value monotonically increases or decreases in response to shear force in any direction △ (generally good): The detected voltage value changes in response to shear force in any direction, but If it is not monotonically increasing or decreasing × (defective): If there is no change in the detected voltage value in response to shear force in any direction

[comprehensive evaluation]
As a criterion for comprehensive evaluation of the stress sensor, only when all the evaluation items were good was evaluated as good: ○. If there are some items that are generally good and there are no items that are bad, the evaluation is rated as generally good: △. If there was a defective item, it was evaluated as poor: ×.

The evaluation results are shown in Table 2.

As can be seen from Table 2, the stress sensors of Examples 1A to 11A had excellent detection characteristics for pressing force and shearing force, and therefore the overall evaluation was generally good or better. From Examples 1A to 10A, it was found that the stress sensor operated even better by optimizing the shape of the adhesive layer, the radius of the detection area, the arrangement of the detection part, the area ratio of the electrodes, and the area of the electrodes. From Example 11A, it was found that stress could be detected without any problem even when the number of detection parts was increased to five.

On the other hand, the stress sensor of Comparative Example 1A was provided with only one detection section, so shear force could not be detected, and therefore the overall evaluation was poor. The stress sensor of Comparative Example 2A had three detection sections arranged in a straight line and could only detect the shear force in the alignment direction of the detection sections, so the overall evaluation was poor. In Comparative Example 3A, since the electrode area ratio was 1, the pressing force was affected by the shearing force, and therefore the overall evaluation was poor.

Examples 1B to 9B that specifically implement the second embodiment will be described below.

<Example 1B>
A polyimide film with a thickness of 25 μm was used as the first base material 31, and

first electrodes

33, 34a, 34b, 35a, and 35b shown in FIG. 14A were formed by a printing method using silver paste. The

first electrodes

33, 34a, 34b, 35a, and 35b were each 0.25 mm x 0.25 mm square. Moreover, a wiring with a width of 0.03 mm was formed at the same time as the first electrode. Next, insulating ink was printed between each second electrode and on the wiring to form an insulating layer (not shown). Next, a first resin layer (not shown) was formed on the

first electrodes

33, 34a, 34b, 35a, and 35b by a printing method using carbon ink. The thickness of the first laminate 11 (see FIG. 14D) in which the first resin layer and the first electrode were laminated was 18 μm.

A polyimide film with a thickness of 25 μm was used as the second base material 32, and the

second electrodes

8, 9a, 9b, 10a, and 10b shown in FIG. 14B were formed by a printing method using silver paste. The

second electrodes

8, 9a, 9b, 10a, and 10b were all squares of 0.2 mm x 0.2 mm. Additionally, a wiring with a width of 0.03 mm was formed at the same time as the electrodes. Next, insulating ink was printed between each second electrode and on the wiring to form an insulating layer (not shown). Next, a second resin layer (not shown) was formed on the

electrodes

8, 9a, 9b, 10a, and 10b by a printing method using carbon ink. The thickness of the second laminate 12 (see FIG. 14D) in which the second resin layer and the second electrode were laminated was 23 μm.

As shown in FIG. 14C, a circular double-sided tape with an inner diameter of 7 mm (inner circumference diameter) and a width of 1 mm is pasted along a circle with a diameter of 7 mm from the center of the electrode 33 of the first base material 31, and the adhesive layer 15 is attached. Formed. The thickness d2 of the adhesive layer 15 was 10 μm. The diameter of the area in which all the first laminates 11 and second laminates 12 are arranged, that is, the circular area (indicated by a dashed-dotted line) whose radius is the distance from the center of the first electrode 33 to the outermost part of the resin layer. A certain pattern size S was 2.5 mm. Further, the shortest distance d3 from the outer peripheral edge of the resin layer to the adhesive layer 15 was 2.25 mm.

The first base material 31 and the second base material 32 were bonded together via the adhesive layer 15 to produce a stress sensor according to Example 1B. The total thickness d1 of the first laminate and the second laminate was 41 μm, and d1/d2 was 4.1. In Example 1B, as shown in FIG. 14D, a shape of the stress sensor 200 was obtained in which the total thickness d1 of the first laminate and the second laminate was larger than the thickness d2 of the adhesive layer 15.

<Examples 2B to 9B, Comparative Examples 1B to 7B>
Except that the total thickness d1 of the first resin layer and the second resin layer, the thickness d2 of the adhesive layer, the shortest distance d3 from the resin layer to the adhesive layer, and the inner diameter of the adhesive layer 15 were changed to the values in Table 3 below. A stress sensor was produced in the same manner as in Example 1B.

[Evaluation method of pressure measurement value]
The stress sensors according to each Example and each Comparative Example were fixed on a measurement stage of a load application device (load cell: ICO Engineering MODEL-3005 (50N)). Apply the measurement terminal to the stress sensor, increase only the vertical load from 0.1N to 10.0N in 0.1N increments without applying shear, obtain the pressure output value of the stress sensor, and compare it with the applied load value. The output value of the stress sensor was compared.

The pressure measurement accuracy of the stress sensor was evaluated using the following criteria.
○: The maximum value of the difference between the applied pressure value and the pressure value output from the sensor is within ±5% △: The maximum value of the difference between the applied pressure value and the pressure value output from the sensor is within ±20% ×: The maximum difference between the applied pressure value and the pressure value output from the sensor exceeds the range of ±20%

[Evaluation method of shear force measurement value]
The stress sensors according to each Example and each Comparative Example were fixed on a measurement stage of a load application device (load cell: ICO Engineering MODEL-3005 (50N)). With a constant vertical load applied to the stress sensor, the shear force output value of the sensor is obtained and applied while increasing the shear loads in the X and Y directions from 0N to 0.3N in 0.05N increments. The obtained shear load value and the obtained shear force output value were compared. In addition, the output value of the sensor's shear force was obtained while decreasing the shear load in the X direction and the Y direction from 0N to -0.3N in 0.05N increments, and the applied shear load value and the obtained shear force were compared with the output value of Note that both the X direction and the Y direction are directions parallel to the surface direction of the stress sensor and orthogonal to each other.

The measurement accuracy of shear force of the stress sensor was evaluated using the following criteria.
○: The maximum value of the difference between the applied shear load value and the shear force value output from the sensor is within ±5% △: The maximum value of the difference between the applied shear load value and the shear force value output from the sensor Within ±20% ×: The maximum value of the difference between the applied shear load value and the shear force value output from the sensor exceeds the range of ±20%.

[comprehensive evaluation]
The overall evaluation of the stress sensor was determined based on the following criteria.
◎: Both the pressure measurement value and the shear force measurement value are evaluated as ○. ○: The evaluation of either the pressure measurement value or the shear force measurement value is △, but the evaluation of the pressure measurement value or the shear force measurement value is Neither is × ×: Either the pressure measurement value or the shear force measurement value is ×

Table 3 shows the dimensions and evaluation results of each part of the stress sensor.

In the stress sensors according to Examples 1B to 9B, d1/d2, which is the ratio of the sum d1 of the thicknesses of the first laminate and the second laminate to the thickness d2 of the adhesive layer, is in the range of 1.1 to 5.0. and the distance d3, whichever is smaller between the minimum value of the distance from the first laminate to the adhesive layer and the minimum value of the distance from the second laminate to the adhesive layer, is 0.75 to 3. It is within the range of 75mm. Therefore, in the stress sensors according to Examples 1B to 9B, the contact state between the first laminate and the second laminate adhesive layer is stable, and stable signal output is possible regardless of the applied pressure and shear load range. It was possible.

On the other hand, in the stress sensor according to Comparative Example 1B, since the sum d1 of the thicknesses of the first laminate and the second laminate is too large with respect to the thickness d2 of the adhesive layer, the first laminate and the second laminate in the initial state are The contact pressure between the two laminates increases. For this reason, the first laminate and the second laminate could not follow either the applied pressure or the shear load, and the measurement error of the shear force was particularly large.

In the stress sensors according to Comparative Examples 2B and 3B, since d1/d2 is less than 1.1, it becomes difficult for the first laminate and the second laminate to contact each other, and the output of all elements deteriorates, resulting in shear The force measurement error was particularly large.

In the stress sensors according to Comparative Examples 4B and 5B, the shortest distance d3 between the first laminate and the second laminate and the adhesive layer is too small, so the distance between the first laminate and the second laminate is affected by the adhesive layer. Movement was poor, and measurement errors for both pressure and shear force were large.

In the stress sensors according to Comparative Examples 6B and 7B, since d3 is too large, the contact position of the first laminated body and the second laminated body is likely to shift regardless of the value of d1/d2, and the contact state is unstable. , the measurement error of shear force was particularly large.

The present invention can be used as a stress sensor that detects pressure and shear force.

1a First base material 1b Second base material 2 Detection areas 21A, 22A, 23A First detection part components 21B, 22B, 23B Second detection part components 21a, 22a, 23a First electrode 21b, 22b, 23b Second Electrodes 21c, 22c, 23c First pressure sensitive layer 21d, 22d, 23d Second pressure sensitive layer 3 Adhesive layer 100 Stress sensor 31 First base material 32 Second base material 33 Electrode (first electrode)
34, 34a, 34b electrode (first electrode)
35, 35a, 35b electrode (first electrode)
6a, 6b, 6c resin layer (first resin layer)
7a, 7b, 7c resin layer (second resin layer)
8 electrode (second electrode)
9, 9a, 9b electrode (second electrode)
10, 10a, 10b electrode (second electrode)
11 First laminate 12 Second laminate 200 Stress sensor

Claims

a first base material;
a second base material;
three or more detection units arranged between the first base material and the second base material;
an adhesive layer provided in a region surrounding a detection area including the three or more detection parts and bonding the first base material and the second base material,
Each of the detection units is
a first sensing part component provided on the first base material and having a first electrode and a first pressure sensitive layer in order from the first base material side;
a second sensing part component provided on the second base material so as to face the first sensing part, and having a second electrode and a second pressure sensitive layer in order from the second base material side;
The area of one of the first electrode and the second electrode is smaller than the area of the other, and the overlapping area of the first electrode and the second electrode is the area of the one of the first electrode and the second electrode. is equal to
A stress sensor, wherein the number of the detection parts existing on an arbitrary straight line passing through the geometric center of the detection area is 1 or more (n-1) or less, where n is the number of the detection parts.
The stress sensor according to claim 1, wherein the adhesive layer is formed in an annular shape.
The three or more detection parts are arranged within a circle with a radius of 5 mm from the geometric center of the detection area,
The geometric center of one of the three or more detection units overlaps the geometric center of the detection area,
The geometric center of one of the remaining detection units is located on a first straight line passing through the center of the detection area,
2. The geometrical center of another one of the remaining detection sections is located on a second straight line that passes through the center of the detection area and is perpendicular to the first straight line. The stress sensor described in .
The stress sensor according to claim 1, wherein the area of one of the first electrode and the second electrode is one-fifth or more and two-thirds or less of the area of the other electrode.
The stress sensor according to claim 1, wherein the area of the one of the first electrode and the second electrode is 0.005 mm 2 or more and 1.5 mm 2 or less in plan view.
The stress sensor according to claim 1, wherein the first electrode and the second electrode have a thickness of 0.01 μm or more and 10 μm or less.
The stress sensor according to claim 1, wherein the first pressure-sensitive layer and the second pressure-sensitive layer have a thickness of 1 μm or more and 100 μm or less.
The adhesive layer is formed in an annular shape,
The three or more detection parts are arranged within a circle with a radius of 5 mm from the geometric center of the detection area,
The geometric center of one of the three or more detection units overlaps the geometric center of the detection area,
The geometric center of one of the remaining detection units is located on a first straight line passing through the center of the detection area,
The geometric center of another one of the remaining detection units is located on a second straight line passing through the center of the detection area and orthogonal to the first straight line,
The area of the one of the first electrode and the second electrode is one-fifth or more and two-thirds or less of the area of the other one,
In plan view, the area of the one of the first electrode and the second electrode is 0.005 mm 2 or more and 1.5 mm 2 or less,
The thickness of the first electrode and the second electrode is 0.01 μm or more and 10 μm or less,
The stress sensor according to claim 1, wherein the first pressure sensitive layer and the second pressure sensitive layer have a thickness of 1 μm or more and 100 μm or less.
forming three or more first electrodes on the first base material;
three or more first sensing units in which the same number of first pressure sensitive layers as the first electrodes are formed so as to cover each of the first electrodes, and the first pressure sensitive layers are stacked on the first electrodes; forming a composition;
forming the same number of second electrodes as the first electrodes on a second base material;
The first sensing part composition, wherein the same number of second pressure sensitive layers as the first electrodes are formed so as to cover each of the second electrodes, and the second pressure sensitive layers are laminated on the second electrodes. forming the same number of second sensing portion components;
The first base material and the second base material are opposed to each other such that each of the first detection part components and each of the second detection part components are opposed to each other, and the first detection part components and the a step of bonding the first base material and the second base material via an adhesive layer provided in a region surrounding the second sensing component,
In the step of forming the first electrode, when the number of the sensing parts is n, the number of the sensing parts existing on any straight line passing through the geometric center of the sensing area is 1 or more and (n-1) or less. forming the first electrode so that
In the step of forming the second electrode, forming the second electrode so that the arrangement of all the second electrodes is a mirror image of the arrangement of all the first electrodes,
The area of one of the first electrode and the second electrode is smaller than the area of the other, and the overlapping area of the first electrode and the second electrode is the area of the one of the first electrode and the second electrode. A method of manufacturing a stress sensor, wherein the first electrode and the second electrode are formed so as to be equal to each other.
a first base material;
a plurality of first laminates provided on one side of the first base material;
a second base material facing the one surface of the first base material;
a plurality of second laminates provided on a surface of the second base material facing the first base material and facing each of the first laminates;
an adhesive layer that is provided to surround the first laminate and the second laminate and adheres opposing surfaces of the first base material and the second base material;
Each of the first laminates has a first electrode and a first resin layer in order from the first base material side,
Each of the second laminates has a second electrode and a second resin layer in order from the second base material side,
The ratio d1/d2 of the sum d1 of the height of the first laminate and the height of the second laminate to the thickness d2 of the adhesive layer is 1.1 to 5.0,
The shortest distance from the outer periphery of the first laminate to the adhesive layer in the plane direction of the first base material, and from the outer periphery of the second laminate to the adhesive layer in the plane direction of the second base material. A stress sensor in which the minimum value d3 of the shortest distance is 0.75 to 3.75 mm.
The stress sensor according to claim 10, wherein the stress sensor detects pressure based on an electrical resistance value between the first electrode and the second electrode that changes depending on a contact area between the first resin layer and the second resin layer. .
An electrical resistance value detected using one set of the first laminate and the second laminate, and an electrical resistance value detected using another set of the first laminate and the second laminate. The stress sensor according to claim 10 or 11, which detects shear stress based on the difference between the stress sensor and the stress sensor.