Patent Application
20230266175
The present invention relates to a measuring device which measures a temperature of a deep portion of an object to be measured such as a living body.
A technique for non-invasively measuring a body temperature of a deep portion of a living body is known in the related art. For example, Japanese Patent Application Publication No. 2020-003291 (“PTL 1”) discloses a technique of estimating a body temperature of a deep portion of a living body by assuming a pseudo one-dimensional model of a living body B, a measuring instrument 50 including a temperature sensor and a heat flux sensor, and outside air.
In the technique disclosed in PTL 1, the body temperature of a deep portion of a living body is estimated by assuming the one-dimensional model of biological heat transfer shown in
In PTL 1, the body temperature of a deep portion of a living body is estimated from the following relational Expression (1):
Expression (1):
Body temperature of deep portion (Tbody)=temperature of contact point between temperature sensor and skin (Tskin)+proportionality coefficient (Rsensor)×heat flux flowing into temperature sensor (Hsignal) (1)
Since the proportionality coefficient (Rsensor) can be obtained by providing a rectal temperature and an eardrum temperature measured by using a sensor such as another temperature sensor as the body temperature of the deep portion (Tbody), the body temperature of the deep portion of the living body can be estimated by measuring the heat flux (Hsignal) flowing into the temperature sensor.
[PTL 1] Japanese Patent Application Publication No. 2020-003291.
However, when a one-dimensional model is assumed as a heat transfer model of a living body as in PTL 1, if heat flows from outside air to a sensor due to the generation of wind or the like, as shown in
This is shown as in
Therefore, when wind or the like is generated, the ratio Leak Ratio becomes large, and the one-dimensional model is no longer established in Hsignal, and in a technique of measuring a body temperature of a deep portion in the related art, there is a problem that the body temperature of a deep portion is erroneously measured when wind or the like is generated around the sensor.
Embodiments of the present invention were made to solve the above-mentioned problem, and an object of embodiments of the present invention is to provide a measuring device capable of preventing a change in thermal resistance between a sensor and outside air and accurately measuring a body temperature of a deep portion even when wind or the like is generated around the sensor.
In order to solve the above problem, embodiments of the present invention relate to a measuring device which includes: a measuring instrument configured to measure a heat flux transported from an object to be measured; a first member having a hollow structure and having the measuring instrument therein; a second member having a hollow structure and configured to cover the first member to form an air layer between the first member and the second member; a third member disposed between the first member and the second member and configured to transport a heat flux from the object to be measured outside the first member to an upper part of the second member; and a fourth member having thermal conductivity and having a shape in which the fourth member surrounds at least a side surface of the first member.
According to embodiments of the present invention, the first member having the measuring instrument and the second member which forms the air layer between the second member and the first member are provided, and the third member which transports a heat flux from the object to be measured outside the first member to the upper part of the second member between the first member and the second member and the fourth member having thermal conductivity and having a shape in which the fourth member surrounds at least the side surface of the first member are further provided. Thus, it is possible to provide a measuring device capable of preventing change in thermal resistance between the sensor and the outside air and accurately measuring the body temperature of a deep portion even when wind is generated around the sensor.
Preferred embodiments of the present invention will be described below. In the following embodiments, the object to be measured is a living body and a surface to be measured on which the measuring device is disposed is a surface of a skin of a living body to be measured.
A measuring device of embodiments of the present invention includes: a first member having a hollow structure and having a measuring instrument for measuring a heat flux therein and a second member having a hollow structure and configured to form an air layer between the first member and the second member which are provided therein; and a third member configured to transport a heat flux from an object to be measured outside the first member to an upper part of the second member between the first member and the second member and a fourth member having thermal conductivity and having a shape in which the fourth member surrounds at least a side surface of the first member which are further provided.
A measuring device of embodiments of the present invention includes in addition to a first member having a measuring instrument for measuring a heat flux and a second member which forms an air layer between the first member and a third member, the third member which transports a heat flux from an object to be measured to an upper part of the second member, and a fourth member which has thermal conductivity and surrounds at least a side surface of the first member so that the temperature of the upper part of the measuring instrument can be raised and the temperature around the measuring instrument can be kept symmetrical. Therefore, it is possible to prevent a change in thermal resistance between the measuring instrument and the outside air, prevent a leak heat flux which causes a measurement error in the temperature of a deep portion, and reduce the ratio Leak Ratio even when wind is generated around the measuring device. A specific configuration of the measuring device of the present embodiment will be described below.
The measuring device 1 of
In the configuration example shown in
The fourth member 40 is made of a material having thermal conductivity, surrounds a side surface of the first member having a hollow structure in which the first member holds the measuring instrument 50 therein and is configured to keep a temperature around the measuring instrument 50 symmetrical. A shape of the fourth member 40 is changed in accordance with a shape of the first member 10. For example, if the first member 10 has a cylindrical shape, the fourth member 40 surrounding the first member 10 is a circular ring.
The measuring instrument 50 disposed inside the first member 10 includes a temperature sensor 50a (first temperature sensor) configured to measure a temperature of a skin SK which is a surface to be measured and a temperature sensor 50b (second temperature sensor) disposed at a position just above the temperature sensor 50a to face the temperature sensor 50a. In the configuration example of
The first member 10 has a hollow structure and the inside thereof is filled with air. It is desirable that the second member 20 be filled with a material having a large thermal resistance and a cavity such as air can be used.
A material (about 0.1 mm) having a small thermal resistance and a thin thickness is preferable for the first member 10 and the second member 20 and polyethylene terephthalate (PET) or the like can be used. It is preferable that a material have a high thermal conductivity to efficiently transport a heat flux as a material of the truncated cone-shaped third member 30 having the hollow shell structure. For example, the third member 30 may be formed of a thin film made of aluminum or the like.
A material having a high thermal conductivity is preferable as a material of the fourth member 40, as in the third member 30, to keep a temperature around the measuring instrument 50 symmetrical. For example, aluminum or the like can be used for the material.
The first member 10 is disposed on the skin SK of the living body B which is a surface to be measured. The first member 10 has a hollow structure in which the first member 10 is formed of a thin film and can have, for example, a cylindrical outer shape. The second member 20 covers the first member 10 and is disposed on the skin SK of the living body B which is a surface to be measured and forms an air layer between the first member 10 and the second member 20. The second member 20 has a hollow structure in which the second member 20 is formed of a thin film like the first member 10 and can have a cylindrical outer shape. Note that the outer shapes of the first member 10 and the second member 20 are not limited to cylindrical shapes, and may be, for example, a rectangular parallelepiped shape having a hollow structure.
A diameter D of a cylindrical shape of the first member 10 and a diameter D of a cylindrical shape of the second member 20 can be set to, for example, 20 mm and 30 mm, respectively. A height t of the second member 20 with respect to the skin SK which is the surface to be measured can be set to, for example, about 6 mm. A height of the first member 10 with respect to the skin SK which is the surface to be measured can be set to, for example, about 3 mm.
In this way, a configuration is provided in which an air layer formed by the first member 10 and an air layer between the first member 10 and the second member 20 outside the first member 10 are formed and air in each of the first member 10 and the second member 20 does not move.
Furthermore, a configuration is provided in which the third member 30 is disposed between the first member 10 and the second member 20 and the upper surface portion of the third member 30 comes into contact with the upper surface portion of the second member 20 so that the heat flux from the living body B is transported to the upper part of the second member 20 outside the first member 10. In the example shown in
The fourth member 40 is constituted to surround a side surface around the first member 10 having a hollow structure in which the fourth member 40 holds the measuring instrument 50 therein. When the fourth member which surrounds the side surface around the first member 10 is provided in addition to the third member 30, since the temperature of the upper part of the measuring instrument is raised, the temperature around the measuring instrument is kept symmetrical, and it is possible to prevent a change in thermal resistance between the measuring instrument and the outside air and to prevent a leak heat flux which causes a measurement error in the temperature of the deep portion even when wind is generated around the measuring instrument.
The temperature sensor 50a is disposed on an inner surface of a bottom surface portion in which the cylindrical first member 10 is in contact with the skin SK which is the surface to be measured. The temperature sensor 50b is disposed on the inner surface of the upper surface portion of the first member 10 to face the temperature sensor 50a at a position just above the temperature sensor 50a. In the configuration example of
In
Although a configuration in which the heat flux H′signal is measured using the pair of temperature sensors 50a and 50b is provided in the configuration example of
In
In
The third member 30 is a member which is disposed in the space between the first member 10 and the second member 20, transports the heat flux from the object to be measured to the upper surface portion of the second member outside the first member so that the temperature of the upper surface portion of the second member, that is, the temperature of the upper part of the measuring instrument 50, is raised, and functions to prevent the leak heat flux HLeak and lower the ratio Leak Ratio. As the configuration of the third member 30, configurations having various shapes can be adopted as long as the configuration can exhibit this function.
For example, when the third member is disposed between the first member and the second member having a cylindrical shape, the third member can be configured to have a circular thrust shape cone. The heat flux from the object to be measured can be transported to the upper surface portion of the second member outside the first member without affecting the heat flux flowing into the measuring instrument 50 by forming the third member in a cone shape. The third member can also be configured to have a truncated cone shape as shown in
Furthermore, the configuration of the third member 30 is not limited to a cone shape or a truncated cone shape and can have other cone shapes. For example, when the second member 20 has a rectangular parallelepiped shape, the third member 30 can have a pyramid shape or a truncated pyramidal shape corresponding to the rectangular parallelepiped shape. More heat flux can be transported to the second member without affecting the heat flux flowing into the measuring instrument 50 and the effect of temperature rise can be enhanced by forming the third member in a truncated pyramidal shape.
Furthermore, as illustrated in
The fourth member 40 is constituted to surround the peripheral side surface of the first member 10 having a hollow structure in which the fourth member 40 holds the measuring instrument 50 therein. When the fourth member which surrounds the side surface around the first member is provided in addition to the third member 30, it is possible to prevent a change in thermal resistance between the measuring instrument 50 and the outside air and to prevent the leak heat flux which causes a measurement error of a temperature of a deep portion even when the temperature of the upper part of the measuring instrument is raised, the temperature around the measuring instrument is kept symmetrical, and wind is generated around the measuring instrument 50.
As the configuration of the fourth member 40, configurations having various shapes can be adopted as long as the shape can exhibit this function.
For example, as shown in
It is preferable that a height H of the fourth member 40 be about 2 mm, an inner diameter D2 be about 3 to 6 mm, and a thickness of a ring in a ring structure be about 1 to 4 mm. It is preferable that an outer shape of the fourth member 40 surrounding the first member lo be the same as that of the first member 10. For example, if the first member 10 has a cylindrical shape, the fourth member 40 surrounding the first member 10 is a circular ring.
In
Here, when the truncated cone-shaped third member 30 is sufficiently large, an end part of a bottom surface of the truncated cone-shaped third member 30 is located at a position in which the end part is sufficiently separated from the measuring instrument 50. Thus, the heat flux from the living body B is collected by the third member 30 and transported to the upper surface portion of the second member 20 outside the first member 10. Furthermore, the heat flux collected by the fourth member 40 is also transported to the upper surface portion of the second member 20.
The heat flux Hplus collected and transported using the truncated cone-shaped third member 30 and the fourth member 40 increases the temperature of the upper surface portion of the second member 20 without affecting the Hsignal, and as a result, the temperature outside the measuring instrument 50 can be raised. In the heat equivalent circuit shown in
The truncated cone-shaped third member 30 is covered with the second member 20 and a distance from the outside air becomes smaller toward the vicinity of the central part in which the measuring instrument 50 is disposed and becomes almost zero near the central part in which the measuring instrument 50 is disposed. Thus, the closer to the vicinity of the center part, the more the suppression effect of the inflow of heat from the outside air to the sensor becomes larger, and the highest reduction effect of the ratio Leak Ratio can be obtained in the vicinity of the center part in which the measuring instrument 50 is disposed. As a result, a difference between the heat flux H′signal measured by the temperature sensor or the heat flux sensor and the Hsignal originally desired to be measured can be reduced and the measurement error can be reduced.
According to the embodiments, the first member 10 having the measuring instrument for measuring heat flux and the second member 20 configured to form the air layer between the second member 20 and the first member 10 are provided, and the third member 30 which transports heat flux from the object to be measured outside the first member 10 and the fourth member 40 surrounding the first member 10 are further provided between the first member 10 and the second member 20. Thus, it is possible to prevent a change in thermal resistance between the sensor and the outside air, to prevent the leak heat flux which causes a measurement error, and to reduce a measurement error at the time of measuring a temperature of a deep portion by lowering the ratio Leak Ratio even when the heat flux transported to the upper surface portion of the second member 20 raises the temperature outside the measuring instrument 50, the temperature around the measuring instrument 50 is kept symmetrical, and wind is generated around the measuring device 1.
The configuration of the measuring device 1 according to an embodiment will be described with reference to
The measuring device 1 includes, for example, the measuring instrument 50, the arithmetic circuit 60, the memory 70, the communication circuit 80 which functions as an I/F circuit with the outside, and the battery 90 which supplies electric power to the arithmetic circuit 60, the communication circuit 80, and the like on a sheet-shaped base material loft
In the configuration example of
In the configuration example of
The memory 70 stores information on a one-dimensional heat transfer model based on the foregoing Expression (1) and the estimation result of the body temperature of the deep portion. The memory 70 can be realized by a predetermined storage region in a rewritable nonvolatile storage device (for example, a flash memory) provided in the measurement system.
The communication circuit 80 outputs the time-series data of the body temperature TC of the deep portion of the living body B generated by the arithmetic circuit 60 to the outside. Such a communication circuit 80 becomes an output circuit to which a USB or other cable can be connected when data or the like is output by wire, but for example, a wireless communication circuit compliant with Bluetooth (registered trademark), Bluetooth Low Energy, or the like may be used.
The sheet-shaped base material 100 functions as a base which has the measuring device 1 including the measuring instrument 50, the arithmetic circuit 60, the memory 70, the communication circuit 80, and the battery 90 installed thereon and includes a wiring (not shown) for electrically connecting these elements. Assuming that the measuring device 1 is connected on the epidermis of a living body, it is preferable to use a deformable flexible substrate for the sheet-shaped base material 100.
Furthermore, the opening is provided in a part of the sheet-shaped base material 100 and the temperature sensor 50a included in the measuring instrument 50 and the heat flux sensor 50c are placed on the base material 100 to be in contact with the surface to be measured of the skin SK of the living body B through the opening.
Here, the measuring device 1 is realized using a computer. Specifically, the arithmetic circuit 60 is realized by performing various data processing in accordance with programs stored in a storage device such as a ROM, a RAM, and a flash memory including a memory 70 provided in the measuring device 1 by, for example, a processor such as a CPU or a DSP. The above program for operating the computer as the measuring device 1 can be recorded on a recording medium or provided through a network.
Note that, although the configuration of the measuring device 1 including the measuring instrument 50 described with reference to
Although the measuring device of embodiments of the present invention have been described above, the present invention is not limited to the embodiments which have been described and various modifications which can be assumed by those skilled in the art can be made within the scope of the invention described in the claims.
1 Measuring device
10 First member
20 Second member
30 Third member
31 Hole
40 Fourth member
50 Measuring instrument
50
a,
50
b Temperature sensors
50
c Heat flux sensor
60 Arithmetic circuit
70 Memory
80 Communication circuit
90 Battery
100 Base material
This patent application is a national phase filing under section 371 of PCT application no. PCT/JP2020/031652, filed on Aug. 21, 2020, which application is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/031652 | 8/21/2020 | WO |
