JP7496119B2 - Tilt Sensors and Wearable Sensors - Google Patents

Description

The present invention relates to a tilt sensor and a wearable sensor.

Known types of tilt sensors include MEMS type, capacitance type, conductive ball type, and cone type (see, for example, Patent Document 1). Of these, MEMS type tilt sensors are increasingly being put to practical use.
Also known is a flexible device in which a sensor is formed on a flexible substrate (see, for example, Patent Document 2). By attaching such a flexible device to clothing or the like, it is possible to monitor human movements and the like.

JP 2009-99521 A JP 2018-105775 A

However, when trying to mount a conventional tilt sensor on a flexible device, soldering is required, which requires the flexible substrate to have high heat resistance, which increases manufacturing costs. In addition, because conventional tilt sensors are hard, cushioning is required to make them comfortable to wear, which makes the flexible device larger.
The present invention has been made in view of the above circumstances, and provides a tilt sensor suitable for a flexible device.

The present invention provides a tilt sensor comprising a first substrate having a first recess, a conductive liquid disposed in the first recess, a first detection terminal, a second detection terminal, a third detection terminal, and a fourth detection terminal, and a control unit, the conductive liquid being arranged so that the conductive liquid moves in response to the tilt of the first substrate, the first, second, third, and fourth detection terminals being arranged on the inner surface of the first recess so as to surround the bottom of the first recess, the first, second, third, and fourth detection terminals being arranged so that they are in a conducting state when in contact with the conductive liquid and are in a non-conducting state when not in contact with the conductive liquid, and the control unit being arranged to detect the tilt based on the conducting or non-conducting state of the first, second, third, and fourth detection terminals.

The first, second, third and fourth detection terminals are arranged on the inner surface of the first recess so as to surround the bottom of the first recess. The conductive liquid is provided so that the conductive liquid moves in the first recess according to the inclination of the first substrate. Therefore, when the first substrate is inclined, the conductive liquid comes into contact with the first, second, third and fourth detection terminals or does not come into contact with them. Since the conductive liquid does not have a fixed shape, it can be deformed to match the shape of the first, second, third and fourth detection terminals. Therefore, the contact area between the first, second, third or fourth detection terminal and the conductive liquid can be increased, and the contact resistance can be reduced. This makes it possible to miniaturize the inclination sensor and increase its sensitivity. Furthermore, since the conductive liquid is soft, it is possible to suppress wear of the first, second, third or fourth detection terminal, thereby making it possible to extend the life of the inclination sensor and reduce the thickness of the first, second, third or fourth detection terminal.
The first, second, third and fourth detection terminals are provided to be in a conducting state when in contact with a conductive liquid having electrical conductivity, and to be in a non-conducting state when not in contact with the conductive liquid, and thus the tilt direction of the first substrate attached to the object can be detected with high accuracy based on the conducting or non-conducting state of the first, second, third and fourth detection terminals using the control unit.

1 is a schematic cross-sectional view of a tilt sensor according to an embodiment of the present invention; 2 is a schematic plan view of a first substrate included in the tilt sensor shown in FIG. 1 . 2 is a schematic plan view of a flexible substrate included in the tilt sensor shown in FIG. 1 . FIG. 2 is a schematic cross-sectional view of a tilted tilt sensor. FIG. 2 is a schematic cross-sectional view of a tilted tilt sensor. FIG. 2 is a schematic cross-sectional view of an inclination sensor turned upside down. 1 is a schematic cross-sectional view of a tilt sensor according to an embodiment of the present invention; 8 is a schematic plan view of a first substrate included in the tilt sensor shown in FIG. 7 . 1 is a schematic cross-sectional view of a tilt sensor according to an embodiment of the present invention; 1 is a schematic plan view of a wearable sensor according to an embodiment of the present invention; FIG. 2 is a schematic perspective view of a diaper having a wearable sensor attached thereto. 11 is a schematic cross-sectional view of the strain sensor taken along dashed line CC in FIG. 10. 1 is a schematic plan view of a humidity sensor included in a wearable sensor. FIG. 14 is a schematic cross-sectional view of the humidity sensor taken along dashed line DD in FIG. 13. This is a photograph of the inclination sensor produced in inclination sensor production experiment 1. Photographs of the tilt sensor fabricated in tilt sensor fabrication experiment 1 are shown in (a) to (c). 1A is a photograph of an element prepared for a current-carrying state detection experiment, and FIG. 1B is an explanatory diagram of the current-carrying state detection experiment. 13 is a graph showing the measurement results of a current-carrying state detection experiment. 13 is a graph showing the measurement results of tilt sensor production experiment 2. 1 is a photograph of the humidity sensor that was fabricated. 1 is a graph showing the change in the resistance change rate of a moisture-sensitive layer. (a) is a photograph of the wearable sensor attached to a diaper, (b) is a photograph of the measurement unit (wireless communication unit), and (c) is a photograph of a smartphone displaying the control screen of the wearable sensor. This is a photograph of a smartphone screen displaying the energized and de-energized states of the tilt sensor when the posture of a doll equipped with a wearable sensor is changed. 13 is a graph showing the measurement results of the strain sensor, humidity sensor, and tilt sensor when an adult male wearing a wearable sensor changes his posture.

The tilt sensor of the present invention comprises a first substrate having a first recess, a conductive liquid disposed in the first recess, a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a control unit. The conductive liquid is disposed so that the conductive liquid moves in response to the tilt of the first substrate. The first, second, third, and fourth detection terminals are disposed on the inner surface of the first recess so as to surround the bottom of the first recess. The first, second, third, or fourth detection terminal is disposed so as to be in a conducting state when in contact with the conductive liquid, and to be in a non-conducting state when not in contact with the conductive liquid. The control unit is disposed so as to detect the tilt and tilt direction based on the conducting or non-conducting state of the first, second, third, and fourth detection terminals.

The conductive liquid is preferably a liquid metal.
The first, second, third, and fourth detection terminals are preferably included in the first, second, third, and fourth detection terminal pairs, respectively. Each detection terminal pair is in a conducting state when the conductive liquid is in contact with the detection terminal pair, and is in a non-conducting state when the conductive liquid is not in contact with the detection terminal pair. This makes it possible to detect the tilt direction of the tilt sensor attached to the target object with high accuracy.
The inclination sensor of the present invention preferably includes a common terminal. The first, second, third or fourth detection terminal is in a conducting state when the conductive liquid is in contact with the detection terminal and the common terminal, and is in a non-conducting state when the conductive liquid is not in contact with the detection terminal and the common terminal. By providing the common terminal, the manufacturing cost of the inclination sensor can be reduced.
The first, second, third and fourth sensing terminals are preferably each a graphene layer.

The surface roughness (maximum height Ry) of the first, second, third and fourth detection terminals and the first recess is preferably 5 μm or more and 100 μm or less, which can reduce wettability with respect to the conductive liquid and prevent the conductive liquid from being divided or stretched in the first recess.
The tilt sensor of the present invention preferably includes a second substrate having a second recess. The first and second substrates are arranged such that the first recess and the second recess face each other to form a chamber. This allows the tilt sensor to detect even if it is upside down when attached to an object.

The tilt sensor of the present invention preferably includes a fifth detection terminal, a sixth detection terminal, a seventh detection terminal, and an eighth detection terminal. The fifth, sixth, seventh, and eighth detection terminals are arranged on the inner surface of the second recess so as to surround the bottom of the second recess. The fifth, sixth, seventh, or eighth detection terminal is provided so as to be in a conducting state when in contact with the conductive liquid, and is provided so as to be in a non-conducting state when not in contact with the conductive liquid. The control unit is also provided so as to detect the tilt and tilt direction based on the conducting or non-conducting state of the first, second, third, fourth, fifth, sixth, seventh, and eighth detection terminals. With such a configuration of the tilt sensor, even if the tilt sensor is turned upside down, it is possible to detect whether the tilt sensor attached to the object is horizontal, tilted, and the tilt direction.

The present invention also provides a wearable sensor including the inclination sensor of the present invention and a flexible substrate carrying a first base material. The control unit is configured to detect the posture of a person or animal wearing the wearable sensor based on the energized or non-energized states of the first, second, third and fourth detection terminals. The use of the wearable sensor of the present invention makes it possible to monitor the posture of a person or animal.
The wearable sensor of the present invention preferably includes a strain sensor mounted on a flexible substrate. The strain sensor includes a stretchable substrate and a second graphene layer provided on the stretchable substrate, the stretchable substrate is configured to stretch together with the second graphene layer in response to abdominal movement accompanying breathing of a person or animal wearing the wearable sensor, and the control unit is configured to detect the breathing based on a change in the conductivity of the second graphene layer. This makes it possible to monitor the breathing of the person or animal wearing the wearable sensor.

The wearable sensor of the present invention preferably includes a humidity sensor mounted on a flexible substrate. The humidity sensor includes a humidity-sensitive layer, the humidity-sensitive layer includes a thiospinel compound, and the constituent elements of the thiospinel compound include zinc, indium, and sulfur. The control unit is configured to detect urination, defecation, or sweating of a person or animal wearing the wearable sensor based on a change in electrical conductivity of the humidity-sensitive layer. This makes it possible to monitor urination, defecation, or sweating of a person or animal wearing the wearable sensor.
The humidity sensor preferably includes a waterproof breathable filter that covers the moisture-sensitive layer, thereby preventing urine or the like from entering the moisture-sensitive layer and affecting the change in electrical resistance of the moisture-sensitive layer.
The control unit preferably includes a measurement unit connected to wiring on the flexible substrate, a wireless communication unit provided to wirelessly transmit data measured by the measurement unit, and an information device provided to wirelessly connect to the wireless communication unit, thereby making it possible to remotely monitor the posture, breathing, urination, etc. of a person or animal wearing the wearable sensor.

The present invention will be described in more detail below with reference to several embodiments. The configurations shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

First embodiment Fig. 1 is a schematic cross-sectional view of the inclination sensor of this embodiment, Fig. 2 is a schematic plan view of a first substrate included in the inclination sensor of this embodiment, and Fig. 3 is a schematic plan view of a flexible substrate included in the inclination sensor of this embodiment. Fig. 1 is a cross-sectional view taken along dashed line A-A in Figs. 2 and 3. Fig. 10 is a schematic plan view of a wearable sensor including the inclination sensor of this embodiment.
The tilt sensor 40 of this embodiment includes a first substrate 2 having a first recess 5, a conductive liquid 6 arranged in the first recess 5, a first detection terminal 4 (4a to 4p), a second detection terminal 4 (4a to 4p), a third detection terminal 4 (4a to 4p), a fourth detection terminal 4 (4a to 4p), and a control unit 7. The conductive liquid 6 is provided so that it moves in response to the tilt of the first substrate 2. The first, second, third, and fourth detection terminals 4 (4a to 4p) are disposed in the first recess 5. The first recess 5 is disposed on an inner surface 25 of the first recess 5 so as to surround the bottom 24, and the first, second, third or fourth detection terminal 4 (4a to 4p) is arranged to be in a conductive state when in contact with the conductive liquid 6, and to be in a non-conductive state when not in contact with the conductive liquid 6, and the control unit 7 is arranged to detect the tilt and the tilt direction based on the conductive state or non-conductive state of the first, second, third and fourth detection terminals 4 (4a to 4p).
The tilt sensor 40 may also include a flexible substrate 14 .

The tilt sensor 40 is a sensor provided to detect tilt and tilt direction. The tilt sensor 40 may have a configuration in which a sensor element 16 is mounted on a flexible substrate 14. For example, the tilt sensor 40 may be attached to clothing, a human body, a pet, or the like (object).
The first substrate 2 is a substrate of the sensor element 16 and has a first recess 5. The material of the first substrate 2 is not particularly limited as long as it is a material that can be a substrate of the sensor element 16, but can be an elastomer material. The elastomer material is, for example, a thermosetting elastomer such as silicone rubber (such as PDMS), fluororubber, urethane rubber, vulcanized rubber (natural rubber, synthetic rubber). This allows the sensor element 16 to have flexibility, and even when the tilt sensor 40 is attached to clothing or to a human body or pet, it is possible to suppress the occurrence of discomfort. In addition, by using a thermosetting elastomer as the material of the first substrate 2, it is possible to irradiate the surface of the recess with a laser and form a fine uneven structure on the surface of the first recess 5, etc. By forming such a fine uneven structure, the wettability of the surface of the first recess 5, etc. with respect to the conductive liquid 6 can be deteriorated.
The material of the first substrate 2 may be an insulating material.

The first recess 5 is a recess provided on the upper surface of the first substrate 2. The first recess 5 can be, for example, a tapered hole having a bottom 24. The opening of the first recess 5 can be circular. The first recess 5 can have an inner side surface 25 surrounding the bottom 24. The inner side surface 25 can be an inclined surface with an angle of 30 degrees or more and 60 degrees or less with respect to the direction perpendicular to the upper surface of the first substrate 2. The inner side surface 25 can be a flat surface or a curved surface. The size of the opening of the first recess 5 can be, for example, 1.2 times or more and 6 times or less the size of the bottom 24. The shape of the bottom 24 can be circular and can be a similar shape to the opening of the first recess 5.

The first recess 5 becomes a part of the chamber 22 that confines the conductive liquid 6 in a movable state. The chamber 22 may be formed by covering the upper part of the first recess 5 with a resin film such as a flexible substrate 14. The chamber 22 may also be formed by disposing a second substrate 11 having a second recess 12 on the upper part of the first substrate 2 and facing the first recess 5 and the second recess 12, as in the tilt sensor 40 shown in FIG. 1. The material of the second substrate 11 may be an elastomer material. The above description of the first substrate 2 also applies to the second substrate 11 unless there is a contradiction. The above description of the first recess 5 also applies to the second recess 12 unless there is a contradiction.
The second substrate 11 may be directly bonded to the first substrate 2 , or may be bonded to a flexible substrate 14 that is bonded to the first substrate 2 .

The tilt sensor 40 has at least four detection terminals 4 (4a to 4p). These detection terminals 4 are arranged on the inner surface 25 of the first recess 5 so as to surround the bottom 24 of the first recess 5. The detection terminals 4 can be arranged so that their ends are located on the bottom 24 side and the element wiring 3 extending from the ends extends outside the first recess 5. The element wiring 3 extending from the detection terminals 4 can be connected to element terminals 15 (15a to 15l) provided on the first substrate 2 outside the first recess. Two detection terminals 4 constitute a detection terminal pair 8 (8a to 8h).

The detection terminal 4, the element wiring 3, and the element terminal 15 are conductive layers, such as graphene layers and metal layers. The detection terminal 4, the element wiring 3, and the element terminal 15 are formed by, for example, printing, transfer, deposition, and the like. When the detection terminal 4, the element wiring 3, and the element terminal 15 are graphene layers, the detection terminal 4, the element wiring 3, and the element terminal 15 can be formed by transferring a laser-induced graphene (LIG) layer formed by irradiating a polyimide film with a _CO2 laser beam onto the first substrate 2. This allows the detection terminal 4 to be formed with an appropriate thickness on the inner surface 25 of the first recess 5.

Each detection terminal pair 8 (8a to 8h) is composed of two detection terminals 4, and the two detection terminals 4 are arranged with a predetermined distance between them. Therefore, when the conductive liquid 6 is not in contact with the two detection terminals 4 constituting the detection terminal pair 8, the two detection terminals 4 are electrically separated, and the detection terminal pair 8 is not in a conducting state (is in a non-conducting state). When the conductive liquid 6 comes in contact with the detection terminal pair 8, the two detection terminals 4 are electrically connected, and the detection terminal pair 8 is in a conducting state.
For example, when the tilt sensor 40 has four detection terminal pairs 8, the four detection terminal pairs 8 surround the bottom 24 of the first recess 5 such that the angle between any two adjacent detection terminal pairs 8 is about 90 degrees. For example, when the tilt sensor 40 has eight detection terminal pairs 8, the eight detection terminal pairs 8 surround the bottom 24 of the first recess 5 such that the angle between any two adjacent detection terminal pairs 8 is about 45 degrees. By having many detection terminal pairs 8 in this way, the tilt sensor 40 can improve the accuracy of tilt direction detection.

The tilt sensor 40 shown in FIG. 1 has eight detection terminal pairs 8 (8a to 8h) and 16 detection terminals 4 (4a to 4p) as shown in FIG. 2. Specifically, the tilt sensor 40 has a detection terminal pair 8a consisting of detection terminals 4a and 4b, a detection terminal pair 8b consisting of detection terminals 4c and 4d, a detection terminal pair 8c consisting of detection terminals 4e and 4f, a detection terminal pair 8d consisting of detection terminals 4g and 4h, a detection terminal pair 8e consisting of detection terminals 4j and 4i, a detection terminal pair 8f consisting of detection terminals 4l and 4k, a detection terminal pair 8g consisting of detection terminals 4m and 4n, and a detection terminal pair 8h consisting of detection terminals 4o and 4p. In addition, the angle between two adjacent detection terminal pairs 8 is 45 degrees. In addition, each of the detection terminals 4a to 4p is connected to one of the element terminals 15a to 15l.

One of the two detection terminals 4 included in the detection terminal pair 8 can be connected to ground via the element terminal 15. This can improve the accuracy of tilt direction detection by the tilt sensor 40. In addition, multiple detection terminals 4 connected to ground can be connected to the same element terminal 15.

The bottom, side and ceiling surfaces of the chamber 22 (in the tilt sensor 40 shown in FIG. 1, the bottom 24 and inner surface 25 of the first recess 5, the bottom 26 and inner surface 27 of the second recess 12, and the surfaces of the detection terminals 4a to 4p) can be surfaces that are poorly wetted (good at repelling) by the conductive liquid 6. This allows the conductive liquid 6 to move quickly within the chamber 22 when the tilt sensor 40 is tilted. It also makes it possible to prevent the conductive liquid 6 from being divided or stretched within the chamber 22. The contact angle between the bottom, side or ceiling surface of the chamber 22 and the conductive liquid 6 can be, for example, 90 degrees or more and 170 degrees or less.
Methods for reducing the wettability of the bottom, side and ceiling surfaces of chamber 22 to conductive liquid 6 include using a material with poor wettability on the bottom, side and ceiling surfaces of chamber 22, spray coating the bottom, side and ceiling surfaces of chamber 22, and forming a fine uneven structure on the bottom, side and ceiling surfaces of chamber 22.
A method for forming the fine uneven structure includes, for example, forming the detection terminals 4a to 4p, and then performing laser scanning processing on the bottom 24 and inner surface 25 of the first recess 5, and also performing laser scanning processing on the bottom 26 and inner surface 27 of the second recess 12.
When a fine uneven structure is formed on the bottom, side and ceiling surfaces of the chamber 22, the surface roughness (maximum height Ry) of the bottom, side and ceiling surfaces of the chamber 22 can be set to 5 μm or more and 100 μm or less.

The flexible substrate 14 is a substrate on which the sensor element 16 is mounted. The material of the flexible substrate 14 is, for example, a plastic such as polyimide, polyester, or polyethylene terephthalate (PET). The flexible substrate 14 may cover the opening of the first recess 5 and become the ceiling of the chamber 22 that contains the conductive liquid 6. In addition, when the first recess 5 of the first substrate 2 and the second recess 12 of the second substrate 11 are opposed to each other to form the chamber 22, the flexible substrate 14 may be located between the first substrate 2 and the second substrate 11 and may have an opening in a portion overlapping with the first recess 5 and the second recess 12. In addition, the flexible substrate 14 may have an opening larger than the second substrate 11, and the first substrate 2 and the second substrate 11 may be bonded to each other through this opening.
The flexible substrate 14 may be a substrate for a wearable sensor 60. In this case, the flexible substrate 14 can be equipped with a strain sensor 45 or a humidity sensor 55, which will be described later.

A plurality of board terminals 18 (18a to 18l) and board wiring 23 that connects the board terminals 18 and the connection terminals 21 can be provided on the flexible board 14. The plurality of board terminals 18 and the board wiring 23 are, for example, a metal layer, a graphene layer, or the like.
The substrate terminals 18 are terminals for connecting to the element terminals 15, the strain sensor terminals, the humidity sensor terminals, etc. The flexible substrate 14 is disposed on the first base material 2 so that the element terminals 15a to 15l and the substrate terminals 18a to 18l overlap each other. The substrate terminals 18 are electrically connected to the element terminals 15 by contact connection, conductive paste, conductive rubber, etc.
1 to 3, substrate terminals 18a, 18b, 18c, 18d, 18e, 18f, 18g, 18h, 18i, 18j, 18k, and 18l are connected to element terminals 15a, 15l, 15k, 15j, 15i, 15h, 15g, 15f, 15e, 15d, 15c, and 15b, respectively.

The connection terminal 21 is a terminal for connecting the board wiring 23 and the control unit 7 .
The control unit 7 is a part that controls the tilt sensor 40. The control unit 7 may also be a part that controls the wearable sensor 60 described later. In this case, the control unit 7 can be provided to control the strain sensor 45 or the humidity sensor 55.
The control unit 7 may include, for example, a microcontroller having a CPU, a memory, a timer, an input/output port, and the like. The control unit 7 may also include an electric circuit or an electronic circuit for detecting a current-carrying state or a current-discharge state between the two detection terminals 4 included in the detection terminal pair 8. The electric circuit or the electronic circuit is, for example, a resistive voltage divider circuit, a voltage measurement circuit, and the like. The control unit 7 may also include a battery or a power supply circuit. The control unit 7 may also include software provided to operate on an information device 57 such as a smartphone or a computer.

The control unit 7 may include a measurement unit 56 that connects to the board wiring 23 on the flexible board 14, a wireless communication unit 52 that is provided so as to be able to wirelessly transmit data measured by the measurement unit 56, and an information device 57 that is provided so as to be able to wirelessly connect to the wireless communication unit 52. The measurement unit 56 and the information device 57 may also be provided so as to be able to communicate via a wire. The information device 57 is, for example, a smartphone 58, a computer, a smartwatch, a mobile terminal, etc.

The conductive liquid 6 is a liquid (including a solution or a suspension) having electrical conductivity, for example, a liquid or suspension having a conductivity of 1 S/m or more. The conductive liquid 6 is, for example, a liquid metal, an ionic liquid, or the like. The conductive liquid 6 is contained in the chamber 22 so that it can move according to the inclination of the tilt sensor 40. The liquid metal is a metal that is liquid at room temperature. The liquid metal is, for example, an indium-gallium-tin alloy (InGaSn), an indium-gallium alloy (InGa), mercury, or the like.
When the first substrate 2 is horizontal, the conductive liquid 6 comes into contact with all of the detection terminal pairs 8a to 8h, as in the tilt sensor 40 shown in Fig. 1. In this case, the two detection terminals 4 constituting the detection terminal pair 8 in all of the detection terminal pairs 8a to 8h are in a conducting state. Therefore, by detecting the conducting state of all of the detection terminal pairs 8a to 8h, the control unit 7 can detect that the first substrate 2 attached to the object is in a horizontal state.

When the first substrate 2 is tilted such that the direction in which the detection terminal pair 8g is arranged is lowered and the direction in which the detection terminal pair 8c is arranged is raised, as in the case of the tilt sensor 40 shown in FIG. 4, the conductive liquid 6 moves toward the detection terminal pair 8g due to gravity. This movement causes the conductive liquid 6 to no longer contact the detection terminal pairs 8b, 8c, and 8d, and these detection terminal pairs 8 are in a non-conductive state. In addition, the conductive liquid 6 is in contact with the other detection terminal pairs 8a, 8e to 8h, and these detection terminal pairs 8 are in a conductive state. Therefore, by detecting such a conductive state and non-conductive state using the control unit 7, the control unit 7 can detect that the first substrate 2 attached to the object is tilted and the direction of tilt.

As in the tilt sensor 40 shown in FIG. 5, when the first substrate 2 is tilted so that the direction in which the detection terminal pair 8c is arranged is lowered and the direction in which the detection terminal pair 8g is arranged is raised, the conductive liquid 6 moves toward the detection terminal pair 8c due to gravity. Due to this movement, the conductive liquid 6 is no longer in contact with the detection terminal pairs 8f, 8g, and 8h, and these detection terminal pairs 8 are in a non-conductive state. In addition, the conductive liquid 6 is in contact with the other detection terminal pairs 8a to 8e, and these detection terminal pairs 8 are in a conductive state. Therefore, by detecting such a conductive state and non-conductive state using the control unit 7, the control unit 7 can detect that the first substrate 2 attached to the object is inclined and the tilt direction.
Tilts in other directions can be detected similarly.

When the first substrate 2 is upside down, as in the tilt sensor 40 shown in FIG. 6, gravity causes the conductive liquid 6 to move to the second recess 12 of the second substrate 11. This movement causes the conductive liquid 6 to lose contact with all of the detection terminal pairs 8a-8h, and these detection terminal pairs 8 become non-conductive. Therefore, by detecting the non-conductive state of all of the detection terminal pairs 8a-8h, the control unit 7 can detect that the first substrate 2 attached to the object is upside down.

Second embodiment Fig. 7 is a schematic cross-sectional view of a tilt sensor of this embodiment, and Fig. 8 is a schematic plan view of a first substrate included in the tilt sensor of this embodiment. Fig. 7 is a cross-sectional view taken along dashed line BB in Fig. 8.
The tilt sensor 40 of the second embodiment includes a common terminal 9 .
In the first embodiment, the tilt and tilt direction are detected by detecting the energized or non-energized state of the two detection terminals 4 that make up the detection terminal pair 8, but in the second embodiment, the tilt or tilt direction is detected by detecting the energized or non-energized state between the common terminal 9 and the detection terminal 4. Other configurations are similar to those of the first embodiment.

The common terminal 9 is disposed on the bottom 24 of the first recess 5. The common terminal 9 can be connected via the element wiring 3 to an element terminal 15i provided on the first substrate 2 outside the first recess.
The tilt sensor 40 has at least four detection terminals 4 (4a to 4h). These detection terminals 4 are arranged on the inner surface 25 of the first recess 5 so as to surround the common terminal 9 arranged on the bottom 24 of the first recess 5. The detection terminals 4 can be provided such that their ends are located on the bottom 24 side and the element wiring 3 extending from the ends extends to the outside of the first recess 5. The element wiring 3 extending from the detection terminals 4 can be connected to element terminals 15 (15a to 15h) provided on the first substrate 2 outside the first recess.

The common terminal 9 is disposed at a predetermined interval from each of the detection terminals 4 (4a to 4h). Therefore, when the conductive liquid 6 is not in contact with the common terminal 9 and the detection terminal 4, the common terminal 9 and the detection terminal 4 are electrically separated, and the detection terminal 4 is not in a conducting state (is in a non-conducting state). When the conductive liquid 6 comes in contact with the common terminal 9 and the detection terminal 4, the common terminal 9 and the detection terminal 4 are electrically connected by the conductive liquid 6, and the detection terminal 4 is in a conducting state.
For example, if the tilt sensor 40 has four detection terminals 4, the four detection terminals 4 surround the common terminal 9 such that the angle between two adjacent detection terminals 4 is about 90 degrees. For example, if the tilt sensor 40 has eight detection terminals 4, the eight detection terminals 4 surround the common terminal 9 such that the angle between two adjacent detection terminals 4 is about 45 degrees. By having many detection terminals 4 in this way, the accuracy of tilt direction detection by the tilt sensor 40 can be improved. In addition, by providing the common terminal 9, the number of element wirings 3, element terminals 15, board terminals 18, and board wirings 23 can be reduced, and the manufacturing cost of the tilt sensor 40 can be reduced.
The control unit 7 can include an electric circuit or electronic circuit for detecting electrical conduction between the common terminal 9 and each of the detection terminals 4 (4a to 4h).

When the first substrate 2 is horizontal, the conductive liquid 6 contacts the common terminal 9 and all of the detection terminals 4a to 4h, as in the tilt sensor 40 shown in FIG. 7. In this case, all of the detection terminals 4a to 4h are in a conducting state. Therefore, by detecting the conducting state of all of the detection terminals 4a to 4h, the control unit 7 can detect that the first substrate 2 attached to the object is in a horizontal state.

When the first substrate 2 is tilted so that the direction in which the detection terminal 4g is arranged is lowered and the direction in which the detection terminal 4c is arranged is raised, gravity causes the conductive liquid 6 to move toward the detection terminal 4g. This movement causes the conductive liquid 6 to no longer contact the detection terminals 4b, 4c, and 4d, and these detection terminals 4 become non-conductive. In addition, the conductive liquid 6 comes into contact with the other detection terminals 4a, 4e to 4h, and these detection terminals 4 become conductive. Therefore, by detecting such conductive and non-conductive states using the control unit 7, the control unit 7 can detect that the first substrate 2 attached to the object is tilted and the direction of tilt.

When the first substrate 2 is tilted so that the direction in which the detection terminal 4c is arranged is lowered and the direction in which the detection terminal 4g is arranged is raised, gravity causes the conductive liquid 6 to move toward the detection terminal 4c. This movement causes the conductive liquid 6 to lose contact with the detection terminals 4f, 4g, and 4h, and these detection terminals 4 become non-conductive. In addition, the conductive liquid 6 comes into contact with the other detection terminals 4a to 4e, and these detection terminals 4 become conductive. Therefore, by detecting such a conductive state and non-conductive state using the control unit 7, the control unit 7 can detect that the first substrate 2 attached to the object is tilted and the direction of tilt.
Tilts in other directions can be detected similarly.

When the first substrate 2 is upside down, gravity causes the conductive liquid 6 to move to the second recess 12 of the second substrate 11. This movement causes the conductive liquid 6 to lose contact with all of the detection terminals 4a to 4h, and all of the detection terminals 4 become non-conductive. Therefore, by detecting the non-conductive state of all of the detection terminals 4a to 4h, the control unit 7 can detect that the first substrate 2 attached to the object is upside down.
Other configurations are similar to those of the first embodiment. Furthermore, the description of the first embodiment also applies to the second embodiment unless there is a contradiction.

Third Embodiment FIG. 9 is a schematic cross-sectional view of a tilt sensor 40 according to the present embodiment.
In the third embodiment, the detection terminal pairs 8 (8a to 8h), element wiring 3, and element terminals 15 (15a to 15l) as shown in Fig. 2 are also provided on the second substrate 11. Furthermore, board terminals 18 (18a to 18l) and board wiring 23 are provided on both sides of the flexible substrate 14. The other configurations are similar to those of the first or second embodiment.

With this configuration, as in the first or second embodiment, when the conductive liquid 6 is located in the first recess 5, the control unit 7 can detect whether the first substrate 2 attached to the object is horizontal or tilted and the tilt direction by detecting the conductive or non-conductive state of the detection terminal pair 8 (8a to 8h) (or the detection terminals 4a to 4h). Furthermore, even if the first substrate 2 attached to the object is upside down (the conductive liquid 6 is located in the second recess 12), the control unit 7 can detect whether the first substrate 2 or the second substrate 11 attached to the object is horizontal or tilted and the tilt direction by detecting the conductive or non-conductive state of the detection terminal pair 8 provided on the second substrate 11.

Here, the case where the detection terminal pair 8 (8a to 8h), the element wiring 3, and the element terminal 15 (15a to 15l) described in the first embodiment are also provided on the second substrate 11 has been described, but the common terminal 9, the detection terminal 4 (4a to 4h), the element wiring 3, and the element terminal 15 (15a to 15i) described in the second embodiment may also be provided on the second substrate 11. Even in this case, even if the first substrate 2 attached to the object is upside down (the conductive liquid 6 is located in the second recess 12), the control unit 7 can detect whether the first substrate 2 or the second substrate 11 attached to the object is horizontal or inclined and the inclination direction by detecting the energized state or non-energized state of the detection terminal 4 provided on the second substrate 11.
Other configurations are similar to those of the first or second embodiment. Furthermore, the description of the first or second embodiment also applies to the third embodiment unless there is a contradiction.

Fourth embodiment The fourth embodiment relates to a wearable sensor. Fig. 10 is a schematic plan view of a wearable sensor 60 of this embodiment, and Fig. 11 is a schematic perspective view of a diaper 59 to which the wearable sensor 60 is attached.
The wearable sensor 60 is a sensor that is provided so that it can be worn by a person or an animal. The wearable sensor 60 may be provided so that it can be attached inside a diaper for an infant or inside underwear for a person receiving care, for example. This makes it possible to prevent the wearable sensor 60 from coming off or shifting after being worn.
The wearable sensor 60 may be a sensor for infant monitoring or a sensor for care.

The wearable sensor 60 can be attached to a diaper 59 or underwear so that, for example, as shown in Figure 11, the inclination sensor 40 is located in the center of the lower abdomen (near the elastic waist belt), the strain sensor 45 is located in the abdomen (near the elastic waist belt), and the humidity sensor 55 is located in the crotch area.
Since the flexible substrate 14, the tilt sensor 40, the strain sensor 45 and the humidity sensor 55 are made of flexible materials, a person or animal can wear the wearable sensor 60 without feeling uncomfortable.

The wearable sensor 60 includes the tilt sensor 40 and the control unit 7 of the first, second or third embodiment. The tilt sensor 40 functions as a posture sensor for the person wearing the wearable sensor 60. The tilt sensor 40 is mounted on a flexible substrate 14. The explanations of the tilt sensor 40, flexible substrate 14, control unit 7, etc. in the first to third embodiments also apply to the fourth embodiment.

In this embodiment, the control unit 7 controls the tilt sensor 40 , the strain sensor 45 and the humidity sensor 55 .
The control unit 7 may include a measurement unit 56 capable of performing measurements using the tilt sensor 40, the strain sensor 45, and the humidity sensor 55, a wireless communication unit 52 capable of wirelessly transmitting data measured by the measurement unit 56, and an information device 57 capable of wirelessly connecting to the wireless communication unit 52. The measurement unit 56 and the wireless communication unit 52 may be disposed near a rubber belt around the waist. The wireless communication unit 52 and the information device 57 may be connected, for example, by Bluetooth (registered trademark).

The control unit 7 can be configured to detect the posture of a person or animal wearing the wearable sensor 60 based on the energized or non-energized state of the first, second, third and fourth detection terminals 4 (4a to 4p) of the inclination sensor 40.
For example, when a person wears the wearable sensor 60 so that the tilt sensor 40 of the first embodiment is located in the center of the lower abdomen and the lower surface of the first substrate 2 is in contact with or facing the lower abdomen (the detection terminal pair 8a is on the head side, the detection terminal pair 8e is on the foot side, the detection terminal pair 8g is on the right side, and the detection terminal pair 8c is on the left side), when the person wearing the wearable sensor 60 is lying on his/her back, the conductive liquid 6 comes into contact with all the detection terminal pairs 8a to 8h as in the tilt sensor 40 shown in FIG. 1. In this case, the two detection terminals 4 constituting the detection terminal pair 8 in all the detection terminal pairs 8a to 8h are in a conducting state. Therefore, by detecting the conducting state of all the detection terminal pairs 8a to 8h, the control unit 7 can detect that the person wearing the wearable sensor 60 is lying on his/her back.

When a person wearing the wearable sensor 60 is sleeping on his/her right side, the first substrate 2 is tilted so that the right side (the side where the detection terminal pair 8g is arranged) is lowered and the left side (the side where the detection terminal pair 8c is arranged) is raised, as in the tilt sensor 40 shown in FIG. 4. In this case, the conductive liquid 6 moves toward the detection terminal pair 8g due to gravity, and the conductive liquid 6 is no longer in contact with the detection terminal pairs 8b, 8c, and 8d, and these detection terminal pairs 8b to 8d are in a non-conductive state. In addition, the conductive liquid 6 is in contact with the other detection terminal pairs 8a, 8e to 8h, so these detection terminal pairs 8 are in a conductive state. Therefore, by detecting such a conductive state and non-conductive state using the control unit 7, the control unit 7 can detect that the person wearing the wearable sensor 60 is sleeping on his/her right side.

When a person wearing the wearable sensor 60 is sleeping on his/her left side, the first substrate 2 is tilted so that the left side (the side where the detection terminal pair 8c is arranged) is lowered and the right side (the side where the detection terminal pair 8g is arranged) is raised, as in the tilt sensor 40 shown in FIG. 5. In this case, the conductive liquid 6 moves toward the detection terminal pair 8c due to gravity, and the conductive liquid 6 is no longer in contact with the detection terminal pairs 8f, 8g, and 8h, and these detection terminal pairs 8 are in a non-conductive state. In addition, the conductive liquid 6 is in contact with the other detection terminal pairs 8a to 8e, so these detection terminal pairs 8 are in a conductive state. Therefore, by detecting such a conductive state and non-conductive state using the control unit 7, the control unit 7 can detect that the person wearing the wearable sensor 60 is sleeping on his/her left side.

When a person wearing the wearable sensor 60 is sleeping face down, the first substrate 2 is turned upside down as in the tilt sensor 40 shown in Fig. 6, and the conductive liquid 6 moves due to gravity to the second recess 12 of the second substrate 11. Due to this movement, the conductive liquid 6 is no longer in contact with any of the detection terminal pairs 8a to 8h, and these detection terminal pairs 8 are in a non-conductive state. Therefore, by detecting the non-conductive state of all the detection terminal pairs 8a to 8h, the control unit 7 can detect that the person wearing the wearable sensor 60 is sleeping face down.
In this way, the control unit 7 can detect the posture of the person wearing the wearable sensor 60 by using the tilt sensor 40. Furthermore, the control unit 7 can sound an alarm when the person wearing the wearable sensor 60 falls asleep on their stomach to notify the guardian, caregiver, etc. of this. Note that there is a risk of suffocation when an infant sleeps on their stomach.

The wearable sensor 60 may include a strain sensor 45 mounted on the flexible substrate 14. The strain sensor 45 functions as a respiration sensor for the person or animal wearing the wearable sensor 60. The wearable sensor 60 is provided such that the strain sensor 45 is located on the abdomen of the person or animal when the person or animal wears the wearable sensor 60.
In abdominal breathing, the abdomen expands when air is taken into the lungs, and contracts when air is exhaled from the lungs. Breathing involves repeated expansion and contraction of the abdomen. By detecting such abdominal movement with the strain sensor 45, the breathing of a person or animal wearing the wearable sensor 60 can be detected.

The strain sensor 45 includes a stretchable substrate 41 and a graphene layer 42 provided on the stretchable substrate 41. Fig. 12 is a schematic cross-sectional view of the strain sensor 45 taken along dashed line CC in Fig. 10 .
The stretchable substrate 41 is a substrate having stretchability, and may be, for example, a substrate made of an elastomer (for example, a silicone rubber film) or a resin film having stretchability due to a kirigami structure. The kirigami structure is a structure in which slits are made in a film so that the film can stretch.
The stretchable substrate 41 can be provided so as to be attached to the abdomen. This allows the stretchable substrate 41 to expand and contract in response to abdominal movement accompanying breathing. The stretchable substrate 41 may be attached to the abdomen by utilizing the adhesiveness of the stretchable substrate 41, or by utilizing an adhesive layer provided on the surface of a stretchable material, or by utilizing an adhesive tape or adhesive.

The graphene layer 42 is a porous layer containing a large number of graphenes, and two adjacent graphenes are bonded by van der Waals forces. The graphene layer 42 is provided on the stretchable substrate 41. Therefore, when the stretchable substrate 41 expands and contracts in response to abdominal movements, the graphene layer 42 also expands and contracts together with the stretchable substrate 41.
The graphene layer 42 may be a laser-induced graphene (LIG) layer. For example, the graphene layer 42 may be formed by irradiating a resin film (e.g., a polyimide film) with laser light to bake and carbonize a part of the resin film to form laser-induced graphene, and transferring the laser-induced graphene onto the stretchable substrate 41 to form the graphene layer 42. In addition, when the stretchable substrate 41 is a resin film (e.g., a polyimide film) having a kirigami structure, the graphene layer 42 may be formed by irradiating the resin film with laser light.
The thickness of the graphene layer 42 can be, for example, not less than 0.1 μm and not more than 300 μm.

The graphene layer 42 has strain sensor terminals 43a and 43b. In addition, the strain sensor terminals 43a and 43b are each connected to the substrate terminal 18 of the flexible substrate 14. This allows the control unit 7 to be electrically connected to the graphene layer 42 via the substrate wiring 23 and the substrate terminal 18, and the control unit 7 can measure changes in the conductivity (electrical resistance) of the graphene layer 42.

When abdominal movement accompanying breathing causes stretchable substrate 41 to stretch and distort graphene layer 42, the piezoresistance effect changes the electrical resistance (conductivity) of graphene layer 42. By measuring this change in electrical resistance of graphene layer 42 using control unit 7, it is possible to detect whether a person or animal wearing wearable sensor 60 is breathing.
In this way, the control unit 7 can detect the breathing of the person or animal wearing the wearable sensor 60 by using the strain sensor 45. Furthermore, the control unit 7 can sound an alarm when the breathing of the person or animal wearing the wearable sensor 60 stops for 10 seconds or more, to notify a guardian, caregiver, or the like of this.

The wearable sensor 60 can include a humidity sensor 55 mounted on the flexible substrate 14. Fig. 13 is a schematic plan view of the humidity sensor 55, and Fig. 14 is a schematic cross-sectional view of the humidity sensor 55 taken along dashed line D-D in Fig. 13. The humidity sensor 55 is a resistive humidity sensor. The humidity sensor 55 can also function as a urination sensor.
The humidity sensor 55 includes a moisture-sensitive layer 46, and a first electrode 47 and a second electrode 48 electrically connected to the moisture-sensitive layer 46. The moisture-sensitive layer 46, the first electrode 47, and the second electrode 48 are disposed on the flexible substrate 14. The humidity sensor 55 may also include a waterproof breathable filter 49 covering the moisture-sensitive layer 46.

The first electrode 47 and the second electrode 48 are electrodes electrically connected to the moisture-sensitive layer 46, and are electrodes for measuring the electrical resistance (conductivity) of the moisture-sensitive layer 46. The method for measuring the electrical resistance of the moisture-sensitive layer 46 may be a two-terminal method or a four-terminal method. The first electrode 47 and the second electrode 48 are, for example, a carbon electrode, a silver electrode, a gold electrode, a platinum electrode, a copper electrode, an aluminum electrode, or the like. The thickness of the first electrode 47 or the second electrode 48 may be, for example, 30 nm or more and 300 μm or less. The interelectrode distance between the first electrode 47 and the second electrode 48 may be, for example, 100 nm or more and 5 mm or less. The first electrode 47 and the second electrode 48 may be opposing comb-shaped electrodes.

When the flexible substrate 14 is a resin film such as a polyimide film, the first electrode 47 and the second electrode 48 may be a laser-induced graphene layer on the surface of the resin film. This allows the electrical resistance of the moisture-sensitive layer 46 to be stably measured. The first electrode 47 and the second electrode 48 may be part of the substrate wiring 23. The first electrode 47 and the second electrode 48 may be electrically connected to the control unit 7 via the substrate wiring 23.

The moisture-sensitive layer 46 is a layer whose electrical resistance changes depending on the humidity, and contains a thiospinel compound. The thiospinel compound is a substance having a _spinel -type crystal structure represented by the chemical formula _AB2X4 (A and B are electropositive elements, and X is an electronegative element (sulfur element)).
The moisture-sensitive layer 46 may be a layer made of a thiospinel compound, or may be a layer containing 90% or more of a thiospinel compound. The moisture-sensitive layer 46 may have a porous structure. The thickness of the moisture-sensitive layer 46 may be, for example, 30 nm or more and 100 μm or less. The moisture-sensitive layer 46 may be formed by, for example, a coating method, a printing method, or the like.

For example, the thiospinel compound contained in the moisture-sensitive layer 46 is a compound represented by ZnIn ₂ S ₄ (zinc diindium tetrasulfide). The stoichiometric ratio may deviate within a range in which the spinel crystal structure can be maintained. A in AB ₂ X ₄ is zinc (Zn), but may contain a small amount (e.g., 5% or less) of cadmium (Cd), iron (Fe), nickel (Ni), manganese (Mn), other transition metal elements, or impurities. B in AB ₂ X ₄ is indium (In), but may contain a small amount (e.g., 5% or less) of aluminum (Al), gallium (Ga), other transition metal elements, or impurities. X in AB ₂ X ₄ is sulfur (S), but may contain a small amount (e.g., 5% or less) of oxygen (O), selenium (Se), or impurities. The moisture-sensitive layer 46 may also contain impurities to reduce the electrical resistance of the moisture-sensitive layer 46. Furthermore, the moisture sensitive layer 46 may contain impurities that are mixed in when ZnIn ₂ S ₄ is synthesized.

The waterproof breathable filter 49 is a filter that allows gas to pass through but not water. The waterproof breathable filter 49 is provided to cover the moisture-sensitive layer 46. This makes it possible to prevent urine or other substances from the person wearing the wearable sensor 60 from entering the moisture-sensitive layer 46, and to suppress the effect of urine or other substances on changes in the electrical resistance of the moisture-sensitive layer 46.

The humidity sensor 55 is disposed so as to be located in the crotch region of a person wearing the wearable sensor 60. When a person wearing the wearable sensor 60 urinates inside the diaper or underwear, the humidity in the crotch region increases, causing a change in the electrical resistance (conductivity) of the moisture-sensitive layer 46. By detecting this change in electrical resistance using the control unit 7, it is possible to detect urination by the person wearing the wearable sensor 60.
In this way, the control unit 7 can detect urination of the person wearing the wearable sensor 60 by using the humidity sensor 55. Furthermore, when the control unit 7 detects urination of the person wearing the wearable sensor 60, it can sound an alarm to notify a guardian, caregiver, or the like of the urination.
In addition, by changing the position at which the humidity sensor 55 is disposed, it is also possible to detect sweating or defecation of a person or animal wearing the wearable sensor 60.
Moreover, the descriptions of the first to third embodiments also apply to the fourth embodiment unless there is a contradiction.

Inclinometer creation experiment 1
A first substrate made of silicone rubber (PDMS) having a tapered hole (first recess) was prepared. The opening of the first recess was a circle with a diameter of 1 cm. The angle between the direction perpendicular to the top surface of the first substrate and the inclination direction of the inner surface of the first recess was about 50 degrees.
Next, a laser-induced graphene (LIG) layer formed by irradiating a polyimide film with a _CO2 laser beam was transferred onto the first substrate (including the inner surface of the first recess) to form eight detection terminal pairs, element wiring, and element terminals. Then, laser scanning processing was performed on the bottom, inner surface, and detection terminal of the first recess to form a fine uneven structure on these surfaces. After that, a liquid metal that is an indium-gallium-tin alloy was poured into the first recess to produce a tilt sensor.
The surface roughness (maximum height Ry) of the detection terminal was 30 μm.

Fig. 15 is a photograph of the tilt sensor before liquid metal is poured into the first recess, and Figs. 16(a) to (c) are photographs of the tilt sensor after liquid metal is poured into the first recess. Fig. 16(a) is a photograph of the tilt sensor in a horizontal state, Fig. 16(b) is a photograph of the tilt sensor in Fig. 16(a) when tilted, and Fig. 16(c) is a photograph of the tilt sensor tilted as in Fig. 16(b) when returned to a horizontal state.
As shown in FIG. 16(a), when the tilt sensor was horizontal, the liquid metal contacted all eight detection terminal pairs. When the tilt sensor was tilted as shown in FIG. 16(b), the liquid metal moved due to gravity and was no longer in contact with the four detection terminal pairs. Furthermore, when the tilt sensor was returned to the horizontal position, the liquid metal returned due to gravity to the center of the first recess and contacted all eight detection terminal pairs as shown in FIG. 16(c). Furthermore, even when the tilt sensor was moved in this way, the liquid metal moved with a large contact angle. Therefore, it was found that the liquid metal moved smoothly according to the tilt of the tilt sensor and was not separated or stretched.

A test element was fabricated to detect the energized state of the detection terminal pair in the experiment for detecting energized state . Figure 17(a) is a photograph of the fabricated test element. Specifically, a laser-induced graphene (LIG) layer formed by irradiating a polyimide film with a _CO2 laser beam was transferred onto a silicone rubber (PDMS) plate to form detection terminals 4a, 4b and element terminals 15a, 15b.

As shown in the explanatory diagram in Fig. 17(b), the fabricated test element was placed on an inclined surface with an inclination angle of 15 degrees, and a resistive voltage divider circuit was connected to the element terminals 15a and 15b. Then, as shown in Fig. 17(b), liquid metal, an indium-gallium-tin alloy, was dropped onto the test element, and the liquid metal was moved over the detection terminals 4a and 4b by gravity. The current-carrying state of the detection terminals 4a and 4b at this time was detected using the resistive voltage divider circuit.
The measurement results are shown in Fig. 18. The graph in Fig. 18 indicates that the detection terminals 4a, 4b are in a non-conductive state when the measurement voltage is about 1V, and that the detection terminals 4a, 4b are in a conductive state when the measurement voltage is about 0.25V.
As shown in FIG. 18, when the dropped liquid metal passes over the detection terminals 4a and 4b, the liquid metal forms a conductive path between the detection terminals 4a and 4b, so that the detection terminals 4a and 4b are in a conductive state.

Inclinometer creation experiment 2
A tilt sensor as shown in FIGS. 1 to 3 was fabricated.
First, a first substrate made of silicone rubber (PDMS) having a tapered hole (first recess) was prepared. The opening of the first recess was a circle with a diameter of 1 cm. The angle between the direction perpendicular to the upper surface of the first substrate and the inclination direction of the inner surface of the first recess was about 50 degrees. A second substrate made of silicone rubber (PDMS) having a tapered hole (second recess) was prepared. The opening of the second recess was a circle with a diameter of 1 cm. The angle between the direction perpendicular to the upper surface of the second substrate and the inclination direction of the inner surface of the second recess was about 50 degrees.

Next, a laser-induced graphene (LIG) layer formed by irradiating a polyimide film with a _CO2 laser beam was transferred onto the first substrate (including the inner surface of the first recess) to form eight detection terminal pairs, element wiring, and element terminals.
Next, a laser scan process was performed on the bottom, inner side surface, and detection terminal of the first recess, and the bottom and inner side surface of the second recess, to form a fine uneven structure on these surfaces.
In addition, a flexible substrate having substrate terminals and substrate wiring was produced by printing silver paste on a polyimide film.
Then, after pouring liquid metal, which is an indium-gallium-tin alloy, into the first recess, the first substrate, the flexible substrate, and the second substrate are stacked together, and the element terminals and the substrate terminals are electrically connected. In addition, a resistive voltage divider circuit is connected to the substrate wiring, so that the energized or non-energized state of the detection terminal pair can be detected. In addition, one of the two detection terminals constituting the detection terminal pair is connected to ground.

The fabricated inclinometer was placed horizontally, tilted, or upside down to measure the voltage division of the detection terminal pair, and the conductive or non-conductive state of the detection terminal pair was detected. The measurement results are shown in FIG.
The measurement results of the detection terminal pairs (1), (2), (3), (4), (5), (6), (7), and (8) in the upper diagram of Figure 19 are shown as graphs (1), (2), (3), (4), (5), (6), (7), and (8) in the lower diagram of Figure 19. In each graph in the lower diagram of Figure 19, the detection terminal pairs are in a non-conducting state when the measurement voltage is approximately 1 V, and are in a conducting state when the measurement voltage is between 0.2 V and 0.6 V.

In addition, during the measurement, the tilt sensor was tilted so that detection terminal pair (5) was lowered in time period A, the tilt sensor was tilted so that detection terminal pair (1) was lowered in time period B, the tilt sensor was turned upside down in time period C, the tilt sensor was tilted so that detection terminal pair (3) was lowered in time period D, the tilt sensor was turned upside down in time period E, the tilt sensor was tilted so that the midpoint between detection terminal pair (2) and detection terminal pair (3) was lowered in time period F, and the tilt sensor was tilted so that the midpoint between detection terminal pair (4) and detection terminal pair (5) was lowered in time period G. In addition, the tilt sensor was kept horizontal between the two time periods.

During time period A, the detection terminal pairs (1), (2), and (8) were in a non-conductive state, while the other detection terminal pairs were in a conductive state. Therefore, the tilt direction of the tilt sensor could be detected.
During time period B, the detection terminal pairs (4), (5), and (6) were in a non-conductive state, while the other detection terminal pairs were in a conductive state. Therefore, the tilt direction of the tilt sensor could be detected.
During time period C, all of the detection terminal pairs were in a non-conductive state, so it was possible to detect that the tilt sensor was upside down.
During time period D, the detection terminal pairs (6), (7), and (8) were in a non-conductive state, while the other detection terminal pairs were in a conductive state. Therefore, the tilt direction of the tilt sensor could be detected.
During time period E, all of the detection terminal pairs were in a non-conductive state, so it was possible to detect that the tilt sensor was upside down.
During time period F, the detection terminal pairs (5), (6), (7), and (8) were in a non-energized state, while the other detection terminal pairs were in a conductive state. Therefore, the tilt direction of the tilt sensor could be detected.
During time period G, the detection terminal pairs (1), (2), (7), and (8) were in a non-conductive state, while the other detection terminal pairs were in a conductive state. Therefore, the tilt direction of the tilt sensor could be detected.
In this manner, it was found that the tilt sensor of the present invention can detect the tilt direction with high accuracy.

Humidity Sensor Fabrication Experiment A humidity sensor as shown in Figs. 13 and 14 was fabricated.
_ZnCl2 (0.25 mmol), _InCl3.4H2O ( _0.5 mmol), and thioacetamide (1.6 mmol) were dissolved in 150 ml of water. The mixture was then annealed for about 5 hours while stirring in a water bath at 95°C. After cooling, _the resulting _ZnIn2S4 was separated from the excess solution using a centrifuge. In this way, _{ZnIn2S4 was} synthesized.
A 130 μm thick polyimide film (flexible substrate 14) was irradiated with a CO ₂ laser (laser output: 3 W) to carbonize the surface of the polyimide film, thereby forming a first electrode 47 and a second electrode 48 (laser-induced graphene (LIG) layer). The first electrode 47 and the second electrode 48 are each a comb-shaped electrode, and the comb portion of the first electrode 47 is located between two comb portions of the second electrode 48, and the comb portion of the second electrode 48 is located between two comb portions of the first electrode 47.

A solution (10 mg/mL) containing the synthesized _ZnIn2S4 was applied onto the first electrode ₄₇ and the second electrode 48 and dried at 100° C. to form a moisture-sensitive layer 46 (thickness: 0.7 μm). Then, a waterproof breathable filter (manufactured by Nitto Denko Corporation) was attached onto the moisture-sensitive layer 46 to produce a humidity sensor as shown in FIG. 13 and FIG. 14.
FIG. 20(1) is a photograph of the humidity sensor after the moisture-sensitive layer 46 has been formed, and FIG. 20(2) is a photograph of the humidity sensor after the waterproof air-permeable filter has been attached.

Water was dripped onto the waterproof, breathable filter to form water droplets. The amount of water droplets was gradually increased in the range of 5 μL to 100 μL. After that, the water droplets on the waterproof, breathable filter were removed. The rate of change in electrical resistance of the moisture-sensitive layer at this time, ΔR/R ₀ (R ₀ : electrical resistance value of the moisture-sensitive layer at the start of measurement, ΔR=R−R ₀ , R: electrical resistance value of the moisture-sensitive layer) was measured. A graph showing the measurement results is shown in FIG. 21.
As shown in Fig. 21, the rate of change in electrical resistance of the moisture-sensitive layer changed depending on the amount of water droplets. When the water droplets were removed, the rate of change in electrical resistance of the moisture-sensitive layer returned to the value at the start of the measurement. Therefore, it was found that the humidity sensor produced can be used to appropriately detect urination, etc.

Wearable sensor fabrication experiment A wearable sensor was fabricated as shown in Figures 10 and 12. The tilt sensor was fabricated in the same manner as in "Tilt sensor fabrication experiment 2," and the humidity sensor was fabricated in the same manner as in "Humidity sensor fabrication experiment."
For the strain sensor, first, a polyimide film was irradiated with _CO2 laser light to bake and carbonize a part of the polyimide film to form laser-induced graphene, and then this laser-induced graphene was transferred onto PDMS (silicone rubber, a stretchable substrate) to form a graphene layer. The PDMS was attached to the polyimide film (flexible substrate) so that the graphene layer was bonded to the substrate terminal, thereby producing a strain sensor.

The fabricated wearable sensor was attached to a diaper. Figure 22(a) is a photograph of the wearable sensor attached to a diaper. A measurement unit (wireless communication unit) as shown in Figure 22(b) was attached to a flexible substrate. The wearable sensor was controlled using a smartphone as shown in Figure 22(c).

The diaper with the wearable sensor attached was worn by a doll, and the posture of the doll was changed so that the tilt sensor was located in the center of the lower abdomen, the strain sensor was located in the abdomen, and the humidity sensor was located in the crotch area. The tilt sensor was positioned so that the lower surface of the first base material was in contact with the abdomen.
23(1)-(5) show photographs of the doll in various positions and photographs of a smartphone screen displaying the energized and de-energized states of the detection terminal pairs 8a-8h of the tilt sensor. On the smartphone screen, a lamp lights up when the detection terminal pair is energized (Sensor ON), and the lamp goes out when the detection terminal pair is de-energized (Sensor OFF).

When the doll was made to sleep on its back as shown in FIG. 23(1), all the lights were on, and it was confirmed through the smartphone that the doll was sleeping on its back. When the doll was made to sleep on its right side as shown in FIG. 23(2), the three lights on the right side, the light on the head side, and the light on the foot side were on, and it was confirmed through the smartphone that the doll was sleeping on its right side. When the doll was made to sleep on its left side as shown in FIG. 23(3), the three lights on the left side, the light on the head side, and the light on the foot side were on, and it was confirmed through the smartphone that the doll was sleeping on its left side. When the doll was made to sleep on its stomach as shown in FIG. 23(4), all the lights were off, and it was confirmed through the smartphone that the doll was sleeping on its stomach. When the doll was made to stand upright as shown in FIG. 23(5), the three lights on the foot side, the light on the right side, and the light on the left side were on, and it was confirmed through the smartphone that the doll was standing upright.
In this way, the posture of a doll equipped with a wearable sensor could be remotely checked using a smartphone.

Next, the manufactured wearable sensor was attached to underwear, and an adult male wore the underwear so that the tilt sensor was located at the center of the lower abdomen (the lower surface of the first base material was in contact with the abdomen), the strain sensor was located at the abdomen, and the humidity sensor was located at the crotch area. Then, measurements were taken using the tilt sensor (posture sensor), strain sensor (breathing sensor), and humidity sensor (urination sensor) while the adult male changed his sleeping position.
When sleeping on one's back, left side, or right side, the strain sensor was able to detect abdominal movement and thus breathing. When sleeping on one's stomach, the strain sensor was unable to detect abdominal movement associated with breathing. This is thought to be because when sleeping on one's stomach, the abdomen becomes pinched between the body and the bed, making it difficult for the abdomen to move.
The humidity detected by the humidity sensor remained almost unchanged.
The results of the current flow state of the detection terminal pair measured by the tilt sensor were similar to those of the above experiment using the doll.
In this way, it was found that the posture, breathing, and urination of a person wearing the wearable sensor can be monitored simultaneously.

2: First substrate 3: Element wiring 4, 4a to 4p: Detection terminal 5: First recess 6: Conductive liquid 7: Control unit 8, 8a to 8h: Detection terminal pair 9: Common terminal 11: Second substrate 12: Second recess 14: Flexible substrate 15, 15a to 15l: Element terminal 16: Sensor element 18, 18a to 18l: Substrate terminal 20: Opening 21: Connection terminal 22: Chamber 23: Substrate wiring 24: Bottom of first recess 25: Inner surface of first recess 26: Bottom of second recess 27: Inner surface of second recess 40: Tilt sensor 41: Stretchable substrate 42: Graphene layer 43a, 43b: Strain sensor terminal 45: Strain sensor 46: Moisture-sensitive layer 47: First electrode 48: Second electrode 49: Waterproof breathable filter 50a, 50b: Humidity sensor terminal 51a, 51b: Humidity sensor wiring 52: Wireless communication unit 53: Waist area 54: Leg area 55: Humidity sensor 56: Measurement unit 57: Information device 58: Smartphone 59: Diaper 60: Wearable sensor

Claims (12)

a first substrate having a first recess, a conductive liquid disposed in the first recess, a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, and a controller;
the conductive liquid is provided so as to move in response to a tilt of the first substrate,
the first, second, third and fourth detection terminals are disposed on an inner surface of the first recess so as to surround a bottom of the first recess;
the first, second, third or fourth detection terminal is provided so as to be in a conducting state when in contact with the conductive liquid, and is provided so as to be in a non-conducting state when not in contact with the conductive liquid;
the control unit is configured to detect the tilt and the tilt direction based on a current-carrying state or a current-de-carrying state of the first, second, third, and fourth detection terminals ;
The first substrate is attached to a flexible substrate;
A tilt sensor, characterized in that the surface roughness (maximum height Ry) of the first, second, third and fourth detection terminals and the first recess is 5 μm or more and 100 μm or less . The tilt sensor according to claim 1, wherein the conductive liquid is a liquid metal. the first detection terminal is included in the first detection terminal pair, and is provided to be in a conducting state when the conductive liquid is in contact with the first detection terminal pair, and is provided to be in a non-conducting state when the conductive liquid is not in contact with the first detection terminal pair;
the second detection terminal is included in the second detection terminal pair, and is provided to be in a conducting state when the conductive liquid is in contact with the second detection terminal pair, and is provided to be in a non-conducting state when the conductive liquid is not in contact with the second detection terminal pair;
the third detection terminal is included in the third detection terminal pair, and is provided to be in a conducting state when the conductive liquid is in contact with the third detection terminal pair, and is provided to be in a non-conducting state when the conductive liquid is not in contact with the third detection terminal pair;
The inclination sensor of claim 1 or 2, wherein the fourth detection terminal is included in a fourth detection terminal pair and is configured to be in a conductive state when the conductive liquid is in contact with the fourth detection terminal pair and to be in a non-conductive state when the conductive liquid is not in contact with the fourth detection terminal pair. A common terminal is further provided,
the first detection terminal is provided to be in a conducting state when the conductive liquid is in contact with the first detection terminal and the common terminal, and is provided to be in a non-conducting state when the conductive liquid is not in contact with the first detection terminal and the common terminal;
the second detection terminal is provided so as to be in a conducting state when the conductive liquid is in contact with the second detection terminal and the common terminal, and is provided so as to be in a non-conducting state when the conductive liquid is not in contact with the second detection terminal and the common terminal;
the third detection terminal is provided so as to be in a conducting state when the conductive liquid is in contact with the third detection terminal and the common terminal, and is provided so as to be in a non-conducting state when the conductive liquid is not in contact with the third detection terminal and the common terminal;
An inclination sensor as described in claim 1 or 2, wherein the fourth detection terminal is configured to be in a conductive state when the conductive liquid is in contact with the fourth detection terminal and the common terminal, and is configured to be in a non-conductive state when the conductive liquid is not in contact with the fourth detection terminal and the common terminal. The tilt sensor according to any one of claims 1 to 4, wherein the first, second, third and fourth detection terminals are each a first graphene layer. Further comprising a second substrate having a second recess;
6. The tilt sensor according to claim 1, wherein the first and second substrates are provided such that the first recess and the second recess face each other to form a chamber. Further comprising a fifth detection terminal, a sixth detection terminal, a seventh detection terminal, and an eighth detection terminal;
the fifth, sixth, seventh and eighth detection terminals are disposed on an inner surface of the second recess so as to surround a bottom of the second recess;
a fifth, sixth, seventh or eighth detection terminal is provided so as to be in a conducting state when in contact with the conductive liquid, and is provided so as to be in a non-conducting state when not in contact with the conductive liquid;
The inclination sensor according to claim 6, wherein the control unit is configured to detect the inclination and the direction of inclination based on the conductive or non-conductive state of the first, second, third, fourth, fifth, sixth, seventh and eighth detection terminals. A wearable sensor comprising the tilt sensor according to any one of claims 1 to 7 and the flexible substrate carrying a first base material,
The control unit is configured to detect the posture of a person or animal wearing the wearable sensor based on the energized or non-energized state of the first, second, third and fourth detection terminals. Further comprising a strain sensor mounted on the flexible substrate,
The strain sensor includes a stretchable substrate and a second graphene layer provided on the stretchable substrate;
the stretchable substrate is provided so as to stretch together with the second graphene layer in response to abdominal movement accompanying breathing of a person or animal wearing the wearable sensor;
The wearable sensor of claim 8 , wherein the control unit is configured to detect the respiration based on a change in electrical conductivity of the second graphene layer. A humidity sensor mounted on the flexible substrate,
The humidity sensor includes a moisture sensitive layer;
The moisture-sensitive layer comprises a thiospinel compound,
The constituent elements of the thiospinel compound include zinc, indium, and sulfur,
The wearable sensor according to claim 8 or 9, wherein the control unit is configured to detect urination, defecation, or sweating of a person or animal wearing the wearable sensor based on a change in conductivity of the moisture-sensitive layer. The wearable sensor of claim 10 , wherein the humidity sensor comprises a waterproof breathable filter covering the moisture sensitive layer. The wearable sensor of any one of claims 8 to 11, wherein the control unit includes a measurement unit connected to wiring on the flexible substrate, a wireless communication unit arranged to enable wireless transmission of data measured by the measurement unit, and an information device arranged to enable wireless connection to the wireless communication unit.