Deep body temperature measurement probe and deep body thermometer

Abstract

To provide a probe for measurement of a deep body temperature and a deep body thermometer capable of further improving measurement accuracy while using a biheat flow method.SOLUTION: A probe 2 for measurement of a deep body temperature comprises: a first heat flow measurement system 5 capable of measuring a first heat flow 5a flowing out of an analyte 9; and a second heat flow measurement system 6 capable of measuring a second heat flow 6a flowing out of the analyte 9. The first heat flow measurement system 5 comprises a first input side heat insulation body 11, a first output side heat insulation body 12, a first input side temperature sensor 15, and a first output side temperature sensor 16. The second heat flow measurement system 6 comprises a second input side heat insulation body 13, a second output side heat insulation body 14, a second input side temperature sensor 17, and a second output side temperature sensor 18. The first output side heat insulation body 12 and the second output side heat insulation body 14 are constituted of a heat insulation body with almost the same heat conductivity as the air.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a probe for measuring core body temperature and a core body thermometer. [Background technology]

[0002] While skin temperature is easily affected by the outside world, the temperature at the core of the body is always stable within a certain range and is called core body temperature. Core body temperature is also adopted by ISO standards and the American Conference of Governmental Industrial Hygienists (ACGIH) (for example, it is stipulated that core body temperature should be kept below 38°C when working in hot conditions). For this reason, core body temperature is a valuable biological information for health and occupational safety, and if it could be measured accurately, it would be useful for improving health management and occupational safety. One method for measuring deep body temperature is to insert a temperature sensor directly into the rectum of the patient (subject), but this method is invasive and causes discomfort to the patient. Therefore, the zero-heat-flow method was proposed as a non-invasive measurement method. This method is currently widely used for monitoring core body temperature during cardiac surgery, but requires a considerable amount of power because it uses an electronic servo-controlled heater. Therefore, the Dual-Heat-Flux method, which can measure core body temperature without using a heater, has been proposed and is attracting attention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 185905A1 [Non-patent literature]

[0004] [Non-Patent Document 1] Kazunari Sakurai, "Development of a Non-invasive Deep Body Thermometer and Its Verification in Basic Experiments" (Master's thesis, Nara Institute of Science and Technology) 2014 (NAIST-IS-MT1251109) Summary of the Invention [Problem to be solved by the invention]

[0005] The dual heat flow method is advantageous in that it is non-invasive and does not require a heater, but it is said to have problems in terms of measurement accuracy, etc. Non-Patent Document 1, which is related to the dual heat flow method, describes the prototype of a probe for measuring deep body temperature using the dual heat flow method, and the results of measuring deep body temperature with the probe. Although a certain level of measurement accuracy has been achieved in measuring deep body temperature using this prototype probe, further improvements in measurement accuracy are expected. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a probe for measuring core body temperature and a core body thermometer that can further improve measurement accuracy while using the dual heat flow method.

[0006] [1] The deep body temperature measuring probe of the present invention is A probe for measuring core body temperature, comprising a first heat flow measurement system capable of measuring a first heat flow flowing out from a subject, and a second heat flow measurement system capable of measuring a second heat flow flowing out from the subject, the first heat flow measurement system includes a first input-side insulator arranged on the subject side, a first output-side insulator stacked on the first input-side insulator, a first input-side temperature sensor arranged upstream of the first input-side insulator, and a first output-side temperature sensor arranged downstream of the first input-side insulator, the second heat flow measurement system includes a second input-side heat insulator arranged on the subject side, a second output-side heat insulator stacked on the second input-side heat insulator, a second input-side temperature sensor arranged upstream of the second input-side heat insulator, and a second output-side temperature sensor arranged downstream of the second input-side heat insulator; The first and second output side heat insulators have substantially the same thermal conductivity as air. The present invention is characterized in that it is configured as follows.

[0007] According to the core body temperature measurement probe of the present invention, the first and second output-side insulators are insulators with thermal conductivity approximately equal to that of air, which reduces interference between the first and second heat flows. As a result, it is possible to provide a core body temperature measurement probe that can further improve measurement accuracy while using the dual heat flow method. Furthermore, through the above-mentioned experiments, the inventors discovered that interference between the first and second heat flows is reduced by using the first and second output-side insulators with thermal conductivity approximately equal to that of air.

[0008] [7] The deep body thermometer of the present invention is the deep body temperature measuring probe; a core body temperature estimation means for estimating a core body temperature using outputs from the first input temperature sensor and the second input temperature sensor, and the first output temperature sensor and the second output temperature sensor of the core body temperature measurement probe; The present invention is characterized by comprising:

[0009] According to the deep body thermometer of the present invention, it is equipped with the above-mentioned deep body temperature measurement probe and deep body temperature estimation means, and the above-mentioned deep body temperature measurement probe reduces interference between the first heat flow and the second heat flow, and the deep body temperature estimation means can estimate the deep body temperature with high accuracy using the temperature measured by the first input side temperature sensor, etc., so it is possible to provide a deep body thermometer that can further improve measurement accuracy while using the dual heat flow method. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram for explaining the deep body temperature measuring probe 2 according to the first embodiment. [Figure 2] 1 is a diagram for explaining a deep body temperature thermometer 1 equipped with a probe 2 for measuring deep body temperature according to a first embodiment. [Figure 3] 2 is a diagram for explaining a thermal equivalent circuit of the deep body temperature measuring probe 2 according to the first embodiment. FIG. [Figure 4]2 is a diagram for explaining the deep body temperature measuring probe 2 (core body thermometer 1) according to the first embodiment in comparison with a comparative example. FIG. [Figure 5] 4 is a diagram for explaining the results of a heat conduction analysis of the deep body temperature measuring probe 2 (core body thermometer 1) according to the first embodiment in comparison with a comparative example. FIG. [Figure 6] 4 is a diagram for explaining a comparison between a measured value of water temperature (core body temperature) and a calculated value (estimated value) obtained using the core body temperature measuring probe 2 according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The core body temperature measuring probe and core body thermometer of the present invention will be described below with reference to Figures 1 to 6. Note that each of the figures described below is a schematic diagram that shows the actual shape, structure, circuitry, etc. in a simplified form.

[0012] [Embodiment 1] [2 deep body temperature measurement probes and 1 deep body thermometer] First, the core body temperature measuring probe 2 and the core body thermometer 1 according to the first embodiment will be described with reference to FIGS. FIG. 1 is a diagram for explaining a probe 2 for measuring deep body temperature according to embodiment 1. FIG. 2 is a diagram for explaining a deep body thermometer 1 equipped with the probe 2 for measuring deep body temperature according to embodiment 1. FIG. 3 is a diagram for explaining a thermal equivalent circuit of the probe 2 for measuring deep body temperature according to embodiment 1. (In this specification, "measurement" and "measurement" are not strictly distinguished but are essentially synonymous.)

[0013] 1, the core body temperature measuring probe 2 according to the first embodiment includes a first heat flow measurement system 5 capable of measuring a first heat flow 5a (first heat flux) flowing out from the subject 9, and a second heat flow measurement system 6 capable of measuring a second heat flow 6a (second heat flux) flowing out from the subject 9. This is to measure (estimate) the core body temperature (TB) by the dual heat flow method.

[0014] The first heat flow measurement system 5 has a first input side insulator 11 (thermal resistance value R1) arranged on the specimen 9 side, a first output side insulator 12 (thermal resistance value R0) stacked on the first input side insulator 11, a first input side temperature sensor 15 (temperature to be measured T1) arranged upstream of the first input side insulator 11, and a first output side temperature sensor 16 (temperature to be measured T3) arranged downstream. The second heat flow measurement system 6 has a second input side insulator 13 (thermal resistance value R2) arranged on the specimen 9 side, a second output side insulator 14 (thermal resistance value R0) stacked on the second input side insulator 13, a second input side temperature sensor 17 (temperature to be measured T2) arranged upstream of the second input side insulator 13, and a second output side temperature sensor 18 (temperature to be measured T4) arranged downstream. Reference numeral 8 denotes the air outside the core body temperature measuring probe 2. The first output-side insulator 12 and the second output-side insulator 14 are made of insulators with thermal conductivity (thermal resistance value R0) approximately the same as that of air. (In this specification, "R0," "R1," "R2," "Rs," and "Rx" are used to mean "thermal resistance" or the "thermal resistance value" of that thermal resistance.)

[0015] Core body temperature is the temperature inside the body, such as the brain and internal organs, and is always stable within a certain range. In contrast, skin temperature is the temperature on the surface of the body and is easily affected by the outside world. In Figure 1, symbol 9 indicates the subject (thermal resistance value Rs). Symbol 9a indicates the surface of the subject (skin), symbol 9b indicates the middle part of the subject, and symbol 9c indicates the deep part of the subject. The deep body temperature TB and temperatures T1 and T2 generally have a relationship in which the deep body temperature TB is higher at the deep part 9c of the subject and lower at the surface 9a of the subject (temperatures T1 and T2). In this embodiment, a human is used as the measurement subject (subject). A gap 20 (a layer of air as an insulating layer) is provided between the first heat flow measurement system 5 and the second heat flow measurement system 6, and independent heat flows (first heat flow 5a, second heat flow 6a) are formed between them. In this specification, "heat flow" is synonymous with "heat flux," and "heat flow" may be referred to as "heat flux."

[0016] Rs is the thermal resistance value between the deep portion 9c of the subject and the surface 9a of the subject. Because the first heat flow measurement system 5 and the second heat flow measurement system 6 are close to each other, the thermal resistance value between the deep portion 9c of the subject and the surface 9a of the subject on the first heat flow measurement system 5 side (left side of the figure) can be expressed as the same thermal resistance value Rs as the thermal resistance value between the deep portion 9c of the subject and the surface 9a of the subject on the second heat flow measurement system 6 side (right side of the figure). Rx is the leakage thermal resistance (value) between the first heat flow measurement system 5 and the second heat flow measurement system 6. In the first embodiment, the leakage thermal resistance value Rx is small and can be ignored. As the temperature sensors (15, 16, 17, 18), for example, contact type temperature sensors such as thermocouples, platinum resistance thermometers, thermistors, etc. are used.

[0017] In the core body temperature measuring probe 2 according to the first embodiment, the first output-side insulator 12 and the second output-side insulator 14 preferably have thermal conductivity within the range of 0.01 to 0.05 W / (m·K). For example, rigid urethane foam (0.023 to 0.04 W / (m·K)), glass wool (0.036 to 0.05 W / (m·K)), wool (0.039 W / (m·K)), cork (0.043 W / (m·K)), glass wool (0.036 to 0.05 W / (m·K)), rigid urethane foam (0.023 to 0.04 W / (m·K)), and general paper (0.05 (to 0.06) W / (m·K)). The thermal conductivity of air is 0.024 to 0.026 W / (m·K) (0 to 20 degrees Celsius).

[0018] In the core body temperature measuring probe 2 according to the first embodiment, the first output-side heat insulator 12 and the second output-side heat insulator 14 are preferably made of heat insulating paper. An example of such heat insulating paper is heat insulating paper (thermal conductivity 0.013 to 0.027 W / (m·K)) manufactured by Hirose Paper Co., Ltd., which is made by adding (mixing) fibers to silica aerogel.

[0019] In the core body temperature measuring probe 2 according to the first embodiment, the first input side insulator 11 and the second input side insulator 13 are preferably insulators having different thermal conductivities. If the thermal conductivities of the first input side heat insulator 11 and the second input side heat insulator 13 are different, their thermal resistance values ​​(R1, R2) will also be different values ​​corresponding to the thermal conductivities.

[0020] In the deep body temperature measuring probe 2 according to the first embodiment, the first input side insulator 11 and the second input side insulator 13 are preferably insulators whose thermal conductivities differ by 5 to 20 times. For example, the first input side insulator 11 can be made of expanded polystyrene (a foamed polystyrene material with a thermal conductivity of 0.01 to 0.05 W / (m·K)) and the second input side insulator 13 can be made of cedar wood (with a thermal conductivity of 0.105 W / (m·K)), resulting in a thermal conductivity difference of approximately 5 times. Alternatively, the first input side insulator 11 can be made of expanded polystyrene (with a thermal conductivity of 0.01 to 0.05 W / (m·K)) and the second input side insulator 13 can be made of ethylene-propylene rubber (with a thermal conductivity of 0.36 W / (m·K)), resulting in a thermal conductivity difference of approximately 18 times. Alternatively, the first input side insulator 11 is made of expanded polystyrene (thermal conductivity 0.01 to 0.05 W / (m·K)) and the second input side insulator 13 is made of chloroprene rubber (thermal conductivity 0.2 to 0.25 W / (m·K)), resulting in a difference in thermal conductivity of approximately 6 to 10 times.

[0021] In the above-described core body temperature measuring probe 2 according to the first embodiment, a heat conductor 19 (shown by a broken line in FIG. 1) may be further provided on the side surfaces of the first input side heat insulator 11 and the second input side heat insulator 13 (the heat conductor 19 does not have to be provided). Here, the term "heat conductor" is contrasted with "heat insulator." While an "heat insulator" has a low thermal conductivity and blocks heat, a "heat conductor" refers to a member that has a high thermal conductivity compared to a heat insulator and transfers heat well. Examples of materials for the heat transfer body 19 include aluminum (thermal conductivity 204 W / (m·K)), copper (general product, 372 W / (m·K)), pure copper (386 W / (m·K)), and silver (418 W / (m·K)).

[0022] As shown in Figure 2, the deep body temperature thermometer 1 of embodiment 1 comprises the above-mentioned deep body temperature measurement probe 2, and a deep body temperature estimation means 22 that estimates the deep body temperature using temperatures T1 to T4 (symbol 21a is a temperature information signal) measured by the first input side temperature sensor 15 and second input side temperature sensor 17 of the deep body temperature measurement probe 2, and the first output side temperature sensor 16 and second output side temperature sensor 18. In addition, "temperature measured by a temperature sensor" may also be rephrased as "temperature measured using a temperature sensor," "temperature measured by a temperature sensor," "temperature measured by a temperature sensor," "temperature obtained by a temperature sensor," or "temperature information from a temperature sensor."

[0023] The core body temperature estimation means 22 calculates the core body temperature TB by, for example, calculating Equation (10) described later, and sets it as an estimated value. It can be configured as either a dedicated circuit or a general-purpose circuit. An example of a general-purpose circuit is a microcomputer. The microcomputer is composed of a CPU (Central Processing Unit), ROM, RAM, an internal bus connecting these, and an interface provided between the internal bus 45 and an external bus (not shown). The CPU executes various processes according to programs stored in the ROM or programs loaded from an external storage device to the RAM. The RAM stores data and other information required by the CPU to execute various processes. The microcomputer calculates and estimates the core body temperature TB by applying temperatures T1 to T4, etc. to equation (10) described below. In this case, the core body temperature estimation means 22 can be said to be a function of the CPU (microcomputer) that calculates and estimates the core body temperature TB.

[0024] The temperature measurement circuit 21 shown in FIG. 2 measures temperatures T1 to T4 by analyzing signals conveying changes in the physical properties of the temperature sensors 15 to 18, whose physical properties change with temperature. For example, if the temperature sensors 15 to 18 are thermistors that measure temperature using changes in the electrical resistance of oxides, the temperatures T1 to T4 are measured from analog signals that change with temperature, converted to digital values, and sent to the core body temperature estimation means 22. The core body temperature estimation means 22 estimates the core body temperature TB by performing calculations using the thermal resistance ratio (thermal resistance ratio between the first input side insulator 11 and the second input side insulator 13) previously stored in memory and the information on the temperatures T1 to T4 sent from the temperature measurement circuit 21. The estimated core body temperature TB information is sent to a tabulating computer or a display device (not shown). The battery 24 serves as the power source for the core body temperature estimation means 22 and other components.

[0025] [Thermal equivalent circuit] Fig. 3 is a diagram for explaining the thermal equivalent circuit of the deep body temperature measuring probe 2 according to embodiment 1. It is a diagram showing the deep body temperature measuring probe 2 shown in Fig. 1 as a thermal equivalent circuit. Matters already mentioned will be omitted from the explanation.

[0026] Ia is the heat flow (value) flowing through the first input-side insulator 11, and Ib is the heat flow (value) flowing through the second input-side insulator 13. Ic is the heat flow (value) flowing through the thermal resistance Rs (thermal resistance value) between the deep portion 9c of the subject and the surface 9a of the subject (skin) of the first heat flow measurement system 5, and Id is the heat flow (value) flowing through the thermal resistance Rs (thermal resistance value) between the deep portion 9c of the subject and the surface 9a of the subject (skin) of the second heat flow measurement system 6. (In this specification, "I" is used to mean "heat flow" or the "heat flow value" of that heat flow.)

[0027] From the thermal equivalent circuit shown in FIG. 3, the following equation holds for the first heat flow measurement system 5. Ia=(T1-T3) / R1 (1) Ic=(TB-T1) / Rs (2) Ia=Ic=(T1-T3) / R1=(TB-T1) / Rs...(3) From equation (3), TB=T1+(T1-T3)×(Rs / R1)...(4) Similarly, the following equation holds for the second heat flow measurement system 6: Ib=(T2-T4) / R2 (5) Id = (TB - T2) / Rs (6) Ib=Id=(T2-T4) / R2=(TB-T2) / Rs...(7) From equation (7) TB=T2+(T2-T4)×(Rs / R2)...(8)

[0028] Here, there is a method to calculate the core body temperature TB by removing Rs using equations (4) and (8). However, when the inventors conducted experiments, it was difficult to calculate the accurate core body temperature.

[0029] Therefore, the inventors decided to find the core body temperature TB by a different method. First, from the thermal equivalent circuit of FIG. 3, the thermal resistance ratio K between the first heat flow measurement system 5 and the second heat flow measurement system 6 is defined as follows: K=[(TB-T2)(T1-T3)] / [(TB-T1)(T2-T4)] ···(9) Then, equation (9) can be transformed into the following equation for calculating the core body temperature TB. TB=T1+(T1-T2)(T1-T3) / [K(T2-T4)-(T1-T3)] ···(10) Based on this idea, the inventors conducted a preliminary experiment and determined the thermal resistance ratio K using the relationship in equation (9). Then, using the relationship in equation (10), they calculated (estimated) the core body temperature TB based on the thermal resistance ratio K determined in the preliminary experiment and the temperatures (T1, T2, T3, T4) measured by the temperature sensors (15, 16, 17, 18). The experiment allowed them to determine an accurate core body temperature. The thermal resistance ratio K can be considered to be a constant at temperatures between 0°C and 40°C, for example.

[0030] That is, the core body thermometer 1 according to the first embodiment is The core body temperature is TB, When the temperatures measured by the first input-side temperature sensor 15 and the second input-side temperature sensor 17, and the first output-side temperature sensor 16 and the second output-side temperature sensor 18 are T1, T2, T3, and T4, respectively, The deep body temperature estimation means 22 includes: Regarding the thermal resistance ratio K between the first heat flow measurement system and the second heat flow measurement system, K=[(TB-T2)(T1-T3)] / [(TB-T1)(T2-T4)] The thermal resistance ratio K, which is determined in advance using the relationship below, and the measured temperatures T1, T2, T3, and T4 are calculated using the following relationship: TB=T1+(T1-T2)(T1-T3) / [K(T2-T4)-(T1-T3)] It is configured to estimate the core body temperature TB by fitting it to the relationship

[0031] [Comparative experiment] 4 is a diagram for explaining the core body temperature measuring probe 2 (core body thermometer 1) according to the first embodiment in comparison with a comparative example. The left side is an explanatory diagram of the comparative example, and the right side is an explanatory diagram of the first embodiment.

[0032] [Deep body temperature measurement probe 2 used in the comparison experiment] 4(a) is a diagram for explaining the structure of the deep body temperature measurement probe. The deep body temperature measurement probe 2 of embodiment 1 (right side) is shown for comparison with the deep body temperature measurement probe 902 of the comparative example (left side), and has the same structure as that described in FIG. In the core body temperature measurement probe 2 used in the comparative experiment, aluminum heat transfer bodies 19 were attached to the sides of the first heat flow measurement system 5 and the second heat flow measurement system 6 (first input side insulator 11 and second input side insulator 13). The first input side insulator 11 was made of polystyrene foam (thermal conductivity 0.01 to 0.05 W / (m·K)), and the second input side insulator 13 was made of chloroprene rubber (thermal conductivity 0.2 to 0.25 W / (m·K)). The first output side insulator 12 and the second output side insulator 14 were made of insulating paper (thermal conductivity 0.013 to 0.027 W / (m·K)).

[0033] The first heat flow measurement system 5 (first input side insulator 11) and the second heat flow measurement system 6 (second input side insulator 13) both have the same cylindrical shape and are separated by a gap 20. Their cross-sectional areas (the cross-sectional area perpendicular to the direction of travel of the first heat flow 5a and the cross-sectional area perpendicular to the direction of travel of the second heat flow 6a) are the same. In addition, their thicknesses (the length in the vertical direction in the figure) are the same.

[0034] Thermistors were used as the temperature sensors 15 to 18. Wiring between the temperature sensors 15 to 18 and the temperature measurement circuit 21 (see FIG. 2) is not shown (the same applies to the other drawings in FIG. 4). The first input-side temperature sensor 15 was placed between the specimen surface 9a and the first input-side heat insulator 11. Specifically, it was placed in a recess in the first input-side heat insulator 11 at a location where it came into contact with the specimen surface 9a. Similarly, the second input-side temperature sensor 17 was placed between the specimen surface 9a and the second input-side heat insulator 13. Specifically, it was placed in a recess provided in the first input-side heat insulator 11 at a location in contact with the specimen surface 9a.

[0035] The first output-side temperature sensor 16 was placed between the first input-side insulator 11 and the first output-side insulator 12, and similarly, the second output-side temperature sensor 18 was placed between the second input-side insulator 13 and the second output-side insulator 14. Specifically, the sensor was placed in a recess provided in the first input-side insulator 11 (second input-side insulator 13) at a location where it contacts the first output-side insulator 12.

[0036] [Deep body temperature measurement probe 902 used in the comparison experiment] The left side of Figure 4(a) shows the deep body temperature measurement probe 902 used in the comparative experiment. This is modeled after the probe structure described in Non-Patent Document 1. The deep body temperature measurement probe 902 has a stepped cylindrical shape. The thick cylindrical part in the center is used as a first heat flow measurement system 905, and the thin concentric cylindrical part on the outside is used as a second heat flow measurement system 906. The entire probe is made of a (foamed) chloroprene rubber insulator 911, and its top and side surfaces are covered with an aluminum cover 919. Note that reference numeral 905a denotes the first heat flow, and reference numeral 905b denotes the second heat flow.

[0037] For each of the temperature sensors 15 to 18, the pair of the first input-side temperature sensor 15 and the first output-side temperature sensor 16 was placed on both ends of the portion where the insulator 911 was thick, and the pair of the second input-side temperature sensor 17 and the second output-side temperature sensor 18 was placed on both ends of the portion where the insulator 911 was thin. The positions of the first input-side temperature sensor 15 and the second input-side temperature sensor 17 were the same as those of the core body temperature measurement probe 2 described above. The first output-side temperature sensor 16 and the second output-side temperature sensor 18 were placed between the insulator 911 and the aluminum cover 919. Specifically, they were placed in a recess provided in the portion of the insulator 911 where it contacted the aluminum cover 919.

[0038] [Experimental] FIG. 4(b) is a diagram for explaining an experimental system in which a comparative experiment was conducted between the deep body temperature measuring probe 2 (embodiment 1) and the deep body temperature measuring probe 902 (comparative example). Instead of the subject's deep part 9c (deep part of the living body), a water bath 130 with a large heat capacity was used, which was placed in a thermo-humidistat chamber (not shown). The water bath 130 with a large heat capacity was used in place of the subject's deep part 9c (deep part of the living body). The temperature (environmental temperature) in the thermo-humidistat chamber was set to a predetermined temperature between 10°C and 30°C. The water temperature (core body temperature TB) was kept almost constant (approximately 37°C). An aluminum tub 133 was floated in the water bath 130, and the core body temperature TB (water temperature equivalent to the core body temperature TB) was measured (estimated). Reference numeral 109 denotes a surrogate subject (simulating a living subject), which consists of a surrogate subject surface 109a (substitute skin simulating living skin, made of a natural rubber sheet), a surrogate subject deep portion 109c (deep living body portion), and a surrogate subject intermediate portion 109b which is the intermediate portion between them. Reference numeral 131a denotes a support rod which supports the temperature sensor 131.

[0039] To explain core body temperature estimation using the core body temperature measurement probe 2, the core body temperature measurement probe 2 or 902 was placed on top of an aluminum tub 133. The temperatures sensed by the temperature sensors 15-18 were measured by the temperature measurement circuit 21 and output to the core body temperature estimation means 22. The core body temperature estimation means 22 then calculated (estimated) the core body temperature TB. Core body temperature estimation will be described in detail later. The actual deep water temperature (core body temperature TB) was measured by a temperature sensor 131 (thermistor) placed in the water bath 130. The predicted temperature was then compared with the actual temperature.

[0040] The core body thermometer of the comparative example is configured similarly to the core body thermometer 1 according to embodiment 1, except for the core body temperature measurement probe 902. The deep water temperature (core body temperature TB) was calculated (estimated) in the same manner as in embodiment 1. An experiment (simulation) was conducted using such an experimental system, and the deep body temperature measurement probes 2, 902 (and deep body thermometers) of the first embodiment and the comparative example were compared.

[0041] The core body temperature measurement probe 2 used in the experiment used polystyrene foam (thermal conductivity 0.01 to 0.05 W / (m·K)) as the first input side insulator 11 and chloroprene rubber (thermal conductivity 0.2 to 0.25 W / (m·K)) as the second output side insulator 14. Both had the same cylindrical shape (diameter 29.96 mm, thickness 11.96 mm). The first output-side insulator 12 and the second output-side insulator 14 were both made of the same disk-shaped insulator (diameter 30 mm, thickness 0.6 mm) and made of insulating paper (thermal conductivity 0.020 W / (m K)). The heat transfer body 19 was an aluminum plate with a thickness of 0.76 mm. The comparative example of the core body temperature measurement probe 902 uses the same chloroprene rubber as the second output side insulator 14 for the insulator 911. The insulator 911 has a stepped cylindrical shape. The lower cylindrical portion has a diameter of 44 mm and a thickness of 5 mm, and the upper cylindrical portion has a diameter of 26 mm and a thickness of 3 mm. The aluminum cover 919 is 1 mm thick.

[0042] [Heat conduction analysis] Figure 5 is a diagram for explaining the results of a thermal conduction analysis of the deep body temperature measurement probe 2 (core thermometer 1) according to embodiment 1, in comparison with a comparative example. It shows the results of thermal analysis by simulation. It shows the results of a thermal conduction analysis (analysis results in the minor axis direction perpendicular to the major axis of the cylinder, i.e., the planar direction of Figure 5) as viewed from above the deep body temperature measurement probe 2, 902 (from above in the direction of the major axis of the cylinder). It is a steady-state analysis (analysis after sufficient time has passed, in a state where the temperature does not change with time). It shows the heat flux (amount of heat that crosses a unit area per unit time). The direction of the vector indicates the direction of the heat flow velocity, and the length of the vector indicates the magnitude of the heat flux. The heat flux (unit: W / m 2 ) and the corresponding color (shown in black and white on the patent drawings).

[0043] The core body temperature measuring probe 2 of embodiment 1 shown on the right has a small, almost negligible heat flow vector (heat flux vector) in the minor axis direction compared to the core body temperature measuring probe 902 of the comparative example shown on the left. In addition, the heat flow vector interfering between the first heat flow 5a and the second heat flow 6a is also small, almost negligible, compared to the heat flow vector interfering between the first heat flow 905a and the second heat flow 906a. Therefore, in the core body temperature measuring probe 2, the directions of the first heat flow 5a and the second heat flow 6a are almost the same as the longitudinal axis, resulting in an ideal dual heat flow. In other words, in the first embodiment, the state is close to the ideal condition of the measurement principle of the dual heat flow method.

[0044] [Estimation of core body temperature (TB) in an experimental system] [Determination of thermal resistance ratio K] A preliminary experiment was conducted to determine the thermal resistance ratio K using equation (9). (1) A preliminary experiment was conducted, in which the core body temperature TB was measured and temperatures T1 to T4 were measured using temperature sensors (15 to 18). The thermal resistance ratio K of the core body temperature measurement probe 2 (in a state of thermal equilibrium in the experimental system shown in Figure 4) was calculated by applying the relationship in equation (9) multiple times. (2) The average value of multiple thermal resistance ratios K was calculated. (3) The measured water temperature (core body temperature TB) was compared with the estimated (calculated) water temperature (core body temperature TB) obtained by applying the average thermal resistance ratio K and temperatures T1 to T4 to the relationship in equation (10), and it was checked whether the difference (error) between the two had become small. If the error was large, the above steps (1) to (3) were repeated. Then, the thermal resistance ratio K that reduces the error was determined.

[0045] [Estimation of core body temperature TB] The value of the thermal resistance ratio K was stored in memory 23 (see Figure 2). The temperature was measured using a temperature sensor (15, etc.) and a temperature measurement circuit 21, and the deep body temperature was calculated (estimated) by calculating equation (10) in deep body temperature estimation means 22.

[0046] [Simulation results] 6 is a diagram for explaining the comparison between the measured water temperature (core body temperature) and the calculated value (estimated value) using the core body temperature measurement probe 2 according to embodiment 1. The diagram plots the changes over time (up to 60 minutes after the environmental temperature was set) of the measured water temperature (actual measured value) and the calculated value (estimated value) using the core body temperature measurement probe 2 when the water temperature was kept at approximately 37°C, which is close to the core body temperature, and the environmental temperature was changed to 10°C, 20°C, and 30°C.

[0047] The environmental temperature immediately before being set to 10°C, 20°C, or 30°C is around 25°C (24.5 to 27°C). Elapsed time 0 minutes corresponds to when the environmental temperature is set to 10°C, 20°C, or 30°C. Then, when the water temperature (corresponding to core body temperature TB) is calculated (computed) based on temperatures T1 to T4 and the calculated value (estimated value) is displayed over time, the calculated value is approximately 25 to 26°C at elapsed time 0 minutes, and immediately thereafter rapidly increases to over 37°C. After that, after 3 minutes have passed, the temperature reaches a steady state, and the difference (error) between the calculated value and the measured temperature (actual temperature) is within ±0.3°C. In contrast, when the deep body temperature measurement probe 902 was used, the calculated value curve was similar to the curve when the deep body temperature measurement probe 2 was used, and a steady state was reached after 10 minutes. However, the difference (error) between the calculated value and the measured temperature (actual temperature) was within ±0.5°C. The error was smaller in the first embodiment than in the comparative example.

[0048] [Effects of the First Embodiment] The deep body temperature measuring probe 2 according to the first embodiment includes a first heat flow measurement system 5 and a second heat flow measurement system 6, with the first heat flow measurement system 5 including a first input-side insulator 11 on the subject 9 side, the second heat flow measurement system 6 including a second input-side insulator 13 on the subject 9 side, and the first output-side insulator 12 and the second output-side insulator 14 being insulators with thermal conductivity substantially the same as that of air, thereby reducing interference between the first heat flow 5a and the second heat flow 6b. This makes it possible to provide a deep body temperature measuring probe 2 that can further improve measurement accuracy while using the dual heat flow method. As mentioned above, the inventors have discovered through experiments that interference between the first heat flow 5a and the second heat flow 6a is reduced by using first output side insulator 12 and second output side insulator 14 that have thermal conductivity approximately the same as that of air.

[0049] By using the core body temperature measurement probe 2, it is possible to measure core body temperature TB in a wearable, small, and high-performance manner, making it possible to use it for the early detection of heatstroke and the health management of infants and young children without restraints or invasiveness. Continuous monitoring of core body temperature TB provides useful biological information for health and occupational safety, and continuous measurement can be useful for managing human health and improving occupational safety.

[0050] Furthermore, according to the above-mentioned deep body temperature measuring probe 2 of embodiment 1, when the first output side insulator 12 and the second output side insulator 14 have a thermal conductivity within the range of 0.01 to 0.05 W / (m·K), it is possible to make the thermal conductivity of the first output side insulator 12 and the second output side insulator 14 approximately the same as the thermal conductivity of air.

[0051] Furthermore, according to the above-mentioned deep body temperature measuring probe 2 of embodiment 1, if the first output side insulator 12 and the second output side insulator 14 are constructed using insulating paper, it becomes possible to easily construct the first output side insulator 12 and the second output side insulator 14.

[0052] Furthermore, according to the above-described deep body temperature measuring probe 2 of embodiment 1, if the first input side insulator 11 and the second input side insulator 13 are insulators with different thermal conductivities, it is possible to make the deep body temperature measuring probe 2 smaller than when the first input side insulator 11 and the second input side insulator 13 are insulators with the same thermal conductivity. In order to make their thermal resistances different when both have the same cross-sectional area, if their thermal conductivities are the same, it is necessary to increase the height of one of them corresponding to the thermal conductivity. However, if their thermal conductivities are different, it is not necessary to increase the height corresponding to the thermal conductivity by using an insulator with a higher thermal conductivity.

[0053] Furthermore, with the core body temperature measuring probe 2 according to the first embodiment, if the first input-side insulator 11 (first heat flow measurement system 5) and the second input-side insulator 13 (second heat flow measurement system 6) have thermal conductivities that differ by 5 to 20 times, it is possible to achieve a good balance between measurement accuracy and miniaturization. For example, if the thermal conductivity is approximately 1.1, which is significantly less than 5 times, the thermal resistance of the first input-side insulator 11 and the thermal resistance of the second input-side insulator 13 are similar, resulting in a small difference in the thermal resistance of the two heat flows and making it difficult to achieve measurement accuracy. On the other hand, if the thermal conductivity is approximately 100, which is significantly more than 20 times, the thickness of one of the first input-side insulator 11 and the second input-side insulator 13 becomes too large compared to the other, making it difficult to miniaturize the core body temperature measuring probe 2 as a whole (because the overall thickness is determined by the thickness of the thicker insulator).

[0054] Furthermore, in the core body temperature measuring probe 2 according to embodiment 1, when the heat transfer body 19 having a high thermal conductivity is provided on the side surface, the desired heat flow (heat flux) in the vertical direction is more easily formed. In other words, it is possible to further reduce the interference between the first heat flow 5a and the second heat flow 6a.

[0055] The deep body thermometer 1 of embodiment 1 is equipped with the above-mentioned deep body temperature measurement probe 2 and deep body temperature estimation means 22, and the above-mentioned deep body temperature measurement probe 2 reduces interference between the first heat flow 5a and the second heat flow 6a, and the deep body temperature estimation means 22 can estimate the deep body temperature with high accuracy using the temperature measured by the first input side temperature sensor 15, etc., so it is possible to provide a deep body thermometer 1 that can further improve measurement accuracy while using the dual heat flow method.

[0056] Furthermore, according to the core body thermometer 1 according to the first embodiment, The core body temperature is TB, When the temperatures measured by the first input-side temperature sensor 15 and the second input-side temperature sensor 17, and the first output-side temperature sensor 16 and the second output-side temperature sensor 18 are T1, T2, T3, and T4, respectively, A deep body temperature estimation means 22, The thermal resistance ratio K between the first heat flow measurement system 5 and the second heat flow measurement system 6 K=[(TB-T2)(T1-T3)] / [(TB-T1)(T2-T4)] The thermal resistance ratio K, which was previously determined using the relationship below, and the measured temperatures T1, T2, T3, and T4 are calculated as follows: TB=T1+(T1-T2)(T1-T3) / [K(T2-T4)-(T1-T3)] ···(10) If the deep body temperature TB is estimated by applying the above relationship, it becomes possible to estimate the deep body temperature TB with even greater accuracy.

[0057] [Embodiment of Core Body Temperature Estimation Method] The core body temperature estimation method may be implemented, for example, as follows. A step of preparing a probe 2 for measuring deep body temperature; A method for estimating deep body temperature, comprising: a deep body temperature estimation step for estimating deep body temperature using temperatures measured by the first input temperature sensor 15 and the second input temperature sensor 17 of the deep body temperature measurement probe 2, and the first output temperature sensor and the second output temperature sensor.

[0058] The thermal resistance ratio K between the first heat flow measurement system 5 and the second heat flow measurement system 6 is K=[(TB-T2)(T1-T3)] / [(TB-T1)(T2-T4)] However, TB: Core body temperature T1: Temperature measured by the first input side temperature sensor 15 T2: Temperature measured by the second input side temperature sensor 17 T3: Temperature measured by the first output side temperature sensor 16 T4: Temperature measured by the second output temperature sensor 18 a thermal resistance ratio determining step for determining the ratio in advance using the relationship: Using the determined thermal resistance ratio K, the temperatures T1, T2, T3 and T4 are calculated as follows: TB=T1+(T1-T2)(T1-T3) / [K(T2-T4)-(T1-T3)] a deep body temperature estimation step of estimating the deep body temperature TB by applying the relationship A method for estimating core body temperature, comprising:

[0059] [Variations] Although the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment and can be modified within the scope of the invention, for example, the following modifications are also possible.

[0060] (1) In the above embodiment, the measurement target is the core body temperature of a human, but the measurement target is not limited to the core body temperature of a human. For example, the measurement target may be the core body temperature of an animal such as a dog, cat, horse, cow, or mouse.

[0061] (2) In the above embodiment, thermistors are used as the temperature sensors 15-18, but the temperature sensors 15-18 are not limited to thermistors. For example, resistance temperature detectors using metals such as platinum, nickel, and copper, whose resistance changes approximately linearly with temperature, may also be used. Furthermore, linear resistors using alloys of nickel or palladium, whose resistance increases approximately linearly with temperature, may also be used.

[0062] (3) In the above embodiment, the temperature sensors 15 to 18 and the temperature measurement circuit 21 (see FIG. 2) are provided separately, but the temperature sensors 15 to 18 are not limited to this configuration. For example, the temperature sensors 15 to 18 may each have a built-in temperature measurement circuit 21 and output the measured temperature digitally (a temperature sensor module or a digital IC temperature sensor). Alternatively, a microcomputer may be used as the temperature measurement means corresponding to the temperature measurement circuit 21. In this case, the temperature measurement means converts the temperature signals (analog signals) of the temperature sensors 15 to 18 into digital temperature measurement signals, for example.

[0063] (4) The above embodiment may be implemented such that the temperature sensors 15 to 18 have a built-in temperature measurement circuit 21 and are configured as devices that output the measured temperature digitally (temperature sensor modules or digital IC temperature sensors), and the deep body temperature estimation means 22 is configured as a microcomputer that processes and calculates equation (10) as a digital signal to calculate the deep body temperature TB and provide an estimated value. [Explanation of symbols]

[0064] 1...Deep body temperature thermometer, 2...Deep body temperature measurement probe, 11...First input side insulator, 12...First output side insulator, 13...Second input side insulator, 14...Second output side insulator, 15...First input side temperature sensor, 16...First output side temperature sensor, 17...Second input side temperature sensor, 18...Second output side temperature sensor, 19...Heat transfer body, 5...First heat flow measurement system, 5a...First heat flow, 6...Second heat flow measurement system, 6a...Second heat flow, 8...Air, 9...Subject, 9a...Subject surface, 9b...Intermediate portion of subject, 9c...Deep portion of subject, 20...Gap, 21...Temperature measurement circuit, 21a...Temperature information signal, 22...Deep body temperature estimation means, 23...Memory, 24...Battery, T1, T2, T3, T4...temperature, TB...core body temperature, R0, R1, R2, R3, R4, Rs, Rx...thermal resistance (thermal resistance value), Ia, Ib, Ic, Id...heat flow (heat flow value), K...thermal resistance ratio, 109...surrogate subject, 109a...surrogate subject surface (surrogate skin), 109b...surrogate subject middle part, 109c...surrogate subject deep part (deep part of the body), 130...water bath, 131...temperature sensor, 131a...support rod, 133...aluminum bucket, 902...core body temperature measurement probe, 905...first heat flow measurement system, 905a...first heat flow, 906...second heat flow measurement system, 906a...second heat flow, 911...insulator, 919...aluminum cover

Claims

1. A probe for measuring core body temperature, comprising a first heat flow measurement system capable of measuring a first heat flow out of a subject, and a second heat flow measurement system capable of measuring a second heat flow out of the subject, the first heat flow measurement system includes a first input-side insulator arranged on the subject side, a first output-side insulator stacked on the first input-side insulator, a first input-side temperature sensor arranged on the upstream side of the first heat flow in the first input-side insulator, and a first output-side temperature sensor arranged on the downstream side, the second heat flow measurement system includes a second input side heat insulator arranged on the subject side, a second output side heat insulator stacked on the second input side heat insulator, a second input side temperature sensor arranged on the upstream side of the second heat flow in the second input side heat insulator, and a second output side temperature sensor arranged on the downstream side; a gap is provided between the first heat flow measurement system and the second heat flow measurement system so that independent heat flows are formed between the first heat flow measurement system and the second heat flow measurement system; the first output-side heat insulator and the second output-side heat insulator are heat insulators having a thermal conductivity in the range of 0.01 to 0.05 W / (m K), The first output-side temperature sensor is disposed between the first input-side insulator and the first output-side insulator, and the second output-side temperature sensor is disposed between the second input-side insulator and the second output-side insulator. A probe for measuring deep body temperature.

2. In the deep body temperature measuring probe according to claim 1, The core body temperature measuring probe is configured to be in a state close to the ideal condition of the measurement principle of the dual heat flow method, in which most of the first heat flow passes from the subject through the first input-side insulator toward the first output-side insulator, and most of the second heat flow passes from the subject through the second input-side insulator toward the second output-side insulator. A probe for measuring deep body temperature.

3. The probe for measuring deep body temperature according to claim 1 or 2, When measuring core body temperature, the first input-side temperature sensor is disposed between the subject and the first input-side insulator, and the second input-side temperature sensor is disposed between the subject and the second input-side insulator. A probe for measuring deep body temperature.

4. The probe for measuring deep body temperature according to any one of claims 1 to 3, The first output-side heat insulator and the second output-side heat insulator are made of heat insulating paper. A probe for measuring deep body temperature.

5. The deep body temperature measuring probe according to claim 4, The heat insulating paper is made by mixing silica aerogel with fibers. A probe for measuring deep body temperature.

6. The probe for measuring deep body temperature according to any one of claims 1 to 5, A heat transfer body having a higher thermal conductivity than the first input side heat insulator and the second input side heat insulator is provided on a side surface of the first input side heat insulator and the second input side heat insulator. A probe for measuring deep body temperature.

7. A probe for measuring deep body temperature according to any one of claims 1 to 6, a temperature measurement circuit connected to the first input temperature sensor, the second input temperature sensor, the first output temperature sensor, and the second output temperature sensor, and configured to measure the respective temperatures based on temperature information from each of the sensors; and a deep body temperature estimation means for estimating a deep body temperature using the temperature measured by the temperature measurement circuit. A deep body thermometer characterized by the above.

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