WO2024225206A1

WO2024225206A1 - Exhalation sensor and blood sugar level measurement device

Info

Publication number: WO2024225206A1
Application number: PCT/JP2024/015652
Authority: WO
Inventors: レイネルボクノットクナナン; 昇司渡辺
Original assignee: 合同会社エイン
Priority date: 2023-04-24
Filing date: 2024-04-19
Publication date: 2024-10-31

Abstract

[Problem] To measure a blood sugar level with high accuracy from a component included in exhaled breath of a user, and to shorten recovery time until the next measurement becomes possible. [Solution] An exhalation sensor 11 included in an exhalation sensor unit 10 built into a blood sugar level measurement device includes, inside a cylindrical carbon nanosheet 12, a heat insulation member 13 and a pair of electrodes 15. A fullerene layer 18 is formed on the inner peripheral surface of the heat insulating member 13, and a heating wire member 14 is disposed inside the heat insulating member 13. A component in exhaled breath of the user is taken into the exhalation sensor 11 and heated by the heating wire member 14 to adhere to the inner peripheral surface of the carbon nanosheet 12, thereby changing the electric resistance value of the carbon nanosheet 12. Based on the changed electric resistance value, the blood glucose level is finally calculated and presented to the user.

Description

Breath sensor and blood glucose measuring device

The present invention relates to a breath sensor and blood glucose level measuring device that can detect with high accuracy the change in electrical resistance caused by the adsorption of components such as acetone in breath, and also calculates blood glucose levels with high accuracy based on the detected results.

　Traditionally, blood glucose levels have generally been measured using blood glucose test kits. The method of measuring blood glucose levels using these test kits involves using a puncture device or needle included in the test kit to collect blood from the patient's fingertip or other part, and then inputting the blood into a blood glucose meter (measuring chip) also included in the test kit to confirm the measurement results, but this places a heavy burden on the patient in terms of blood collection, etc.

In addition, various components contained in the human breath are detected and human symptoms are analyzed based on the detection results, and attempts have been made to measure blood glucose levels by detecting the concentration of such components (mainly acetone) contained in the breath. For example, the following Patent Document 1 discloses a sensing element that uses nanostructures such as carbon nanotubes to detect the acetone concentration in breath at room temperature levels.

Specifically, when acetone in the breath adheres to the nanostructure while a voltage is applied to the nanostructure, the value of the current flowing through the nanostructure changes, and the electrical resistance of the nanostructure also changes accordingly; by detecting this change in electrical resistance, it is possible to detect the concentration of acetone adhered to the nanostructure, i.e., the acetone concentration in the breath. It is known that the acetone concentration in the breath is highly related to diabetes, and when the acetone concentration in the breath increases, the symptoms of diabetes generally become more likely to occur (see paragraphs 0038, 0043-0045, 0057, etc. of Patent Document 1).

Furthermore, in the following Patent Document 2, various sensors and devices are described as Examples 1 to 9, and in Example 6, it is described that the acetone concentration is detected from the change in electrical resistance caused by the oxidation reaction between acetone and atmospheric oxygen adsorbed on the surface of a semiconductor sensor containing a surface modification paste such as tin oxide or zinc oxide. When measuring the acetone concentration in this way, the semiconductor sensor is heated to 300 to 400°C by a heater wire (see the description in paragraphs 0036, 0037, etc. of Patent Document 2).

JP 2010-107310 A JP 2001-349888 A

In the above-mentioned Patent Document 1, nanostructures such as carbon nanotubes are used to detect the concentration of acetone and other substances contained in breath, but because the detection is performed at room temperature, the activation of the components in the breath to be detected does not progress sufficiently, and the electrical resistance also changes slowly, making it difficult to grasp the final detected value that has completely changed, and therefore difficult to detect the exact concentration.

In the above-mentioned Patent Document 2, the semiconductor sensor is heated to 300-400°C by a heater wire, which provides sufficient heat to the components in the breath and promotes reactions such as oxidation. However, because it does not use nanostructures such as carbon nanotubes, it is difficult to reliably adsorb the components contained in the breath, and as a result, there is a problem that it is difficult to detect changes in electrical resistance with high accuracy.

In addition, in both

Patent Documents

1 and 2, after detection, unnecessary gas components and moisture components in the breath remain in the sensor, so it is necessary to wait a sufficient amount of time before the next detection, which means that it takes a long time to recover to a detectable state, making it difficult to use.

The present invention was made in consideration of these circumstances, and aims to provide a breath sensor and blood glucose measuring device that uses nanostructures to detect changes in electrical resistance due to the adhesion of components in breath, resulting in a clear change in electrical resistance value, making it easier to grasp the detected value with high accuracy.

The present invention also aims to provide a breath sensor and blood glucose measuring device that are easier to use by shortening the time it takes to recover from a detection to a state where the next detection is possible.

In order to solve the above problems, the present invention provides a breath sensor equipped with a carbon nanostructure that has the property of changing its electrical resistance when components contained in the breath adhere to it, the carbon nanostructure is formed in a cylindrical shape, and is equipped with a heating wire member disposed inside the carbon nanostructure and a pair of electrodes electrically connected to the carbon nanostructure, and an opening formed on one end side of the carbon nanostructure serves as an intake port for the breath.

In the present invention, a heating wire member is placed inside a cylindrical carbon nanostructure, and an opening on one end of the cylindrical carbon nanostructure serves as an intake port for exhaled air, so that the exhaled air containing the components to be detected flows smoothly into the cylindrical carbon nanostructure and is heated by the heating wire member placed inside. When the components contained in the exhaled air are heated in this way, the components are activated and reactions such as oxidation are promoted, and the electrical resistance of the carbon nanostructure to which the heated components are attached tends to change significantly, making it possible to detect changes in electrical resistance with high accuracy.

The present invention is characterized in that it includes an annular insulating member disposed inside the carbon nanostructure, and the heating wire member is disposed inside the insulating member.

In the present invention, a ring-shaped insulating member is placed inside the carbon nanostructure, and a heating wire member is placed inside the insulating member, so that the insulating member is between the heating wire member and the carbon nanostructure, and the heat generated by the heating wire member is less likely to be transmitted to the carbon nanostructure by the insulating member. This prevents the carbon nanostructure from becoming too hot, and even if the components in the exhaled breath are heated by the heating wire member, the thermal effect on the carbon nanostructure is suppressed, making it possible to stably detect resistance changes.

The present invention is characterized in that a fullerene layer is formed on the inner peripheral surface of the annular insulating member.

In the present invention, a fullerene layer is formed on the inner circumferential surface of the insulating member, so that the detection results for changes in electrical resistance become stable and the time until the next detection becomes possible is shortened. First, since fullerenes have insulating properties, by forming a fullerene layer on the inner circumferential surface of the insulating member, the insulating properties of the insulating member are enhanced. As a result, the heat generated by the heating wire member placed inside the insulating member is further inhibited from being transmitted to the carbon nanostructure, the thermal effect on the carbon nanostructure is further suppressed, and changes in electrical resistance can be detected more stably.

In addition, not all of the components in the breath taken into the carbon nanostructure immediately adhere to the carbon nanostructure, and residual components (unnecessary gas components) are generated that float inside the carbon nanostructure. When these residual components are gradually adsorbed into the carbon nanostructure over time, the value of the electrical resistance changes from time to time and becomes unstable, affecting the stable detection of electrical resistance. In addition, when breath is blown into the carbon nanostructure, the amount of moisture increases inside the carbon nanostructure, and this moisture also affects the change in electrical resistance.

Furthermore, even if detection of changes in electrical resistance has been completed, if such residual components or moisture remain suspended inside the carbon nanostructure, it will be necessary to wait until the next detection is performed until the components have decreased to a level that does not affect the next detection.

However, since fullerenes have the property of efficiently adsorbing and absorbing components contained in the surrounding gas, in the present invention, as described above, a fullerene layer is formed on the inner surface of the insulating member. This fullerene layer adsorbs the remaining components (unnecessary gas components) and moisture components floating inside the carbon nanostructure, reducing these components. This makes it easier to determine the detection results of changes in electrical resistance, enabling stable detection and also shortening the time until the next detection is possible.

The present invention is characterized in that the negative electrode of the pair of electrodes contains fullerene.

In the present invention, fullerene is contained in the negative electrode of the electrode. Fullerene has excellent conductive properties and, as described above, has the property of efficiently adsorbing components in gas. This makes it easier to detect changes in the electrical resistance of the carbon nanostructures that adsorb components in the breath, and also contributes to shortening the time until the next detection.

The present invention is characterized in that the heating wire member is made of copper nanowires coated with nanosilver.

In the present invention, the heating wire member made of copper nanowire is coated with nanosilver, which ensures efficient heating of the components in the breath and contributes to shortening the time until the next detection is possible. In other words, the heating wire member uses copper nanowire, which makes it possible to efficiently heat the components in the breath, but the heating process makes the surface of the copper nanowire itself prone to oxidation. If the surface of the copper nanowire is oxidized, it will affect the next detection and it will take time to return to a detectable state. However, by coating the copper nanowire with nanosilver, which has antibacterial and antiviral properties, the heating wire member made of copper nanowire can be stabilized and also helps to shorten the time until the next detection is possible. The coating with nanosilver can be applied to the entire surface of the heating wire member, or it can be applied partially so that part of the surface is exposed.

The present invention is characterized in that the heating wire member has a wound coil portion and a net-like mesh portion formed around the coil portion.

In the present invention, a net-like mesh portion is formed around the wound coil portion as the heating wire member, so that the breath taken into the carbon nanostructure not only flows in so as to come into contact with the coil portion, but also flows so as to pass through the mesh portion, increasing the degree of contact with the heating wire member. As a result, the components in the breath are heated efficiently, and the change in the electrical resistance of the carbon nanostructure becomes more noticeable, improving detection accuracy.

The present invention is characterized in that the blood glucose level measuring device comprises the above-mentioned breath sensor, an electrical resistance detection means for detecting a change in the electrical resistance of the carbon nanostructure contained in the breath sensor, a blood glucose level calculation means for calculating the blood glucose level based on the detection result of the electrical resistance detection means, and an output means for outputting the calculation result of the blood glucose level calculation means.

In the present invention, the above-mentioned breath sensor is used to calculate blood glucose levels based on the detection results of changes in the electrical resistance of the carbon nanostructures, making it possible to calculate blood glucose levels with high accuracy, and the time required to perform the next blood glucose level calculation after one calculation can be shortened compared to conventional methods, greatly improving usability.

In the present invention, the components in the breath that are to be attached to the carbon nanostructures are heated, which makes the change in the electrical resistance of the carbon nanostructures more noticeable than in the past, thereby improving detection accuracy.

In addition, in this invention, the heat generated by the heating wire is less likely to be transmitted to the carbon nanostructure by using a heat insulating material, which prevents high temperatures from affecting the detection of changes in electrical resistance and enables stable detection of changes in resistance.

Furthermore, in the present invention, by forming a fullerene layer on the inner peripheral surface of the insulating member, stable electrical resistance detection results can be obtained with high accuracy, and the time until the next detection is possible can be shortened compared to conventional methods.

Furthermore, in the present invention, fullerene is used for the negative electrode, which allows for good detection of changes in electrical resistance and contributes to shortening the time until the next detection is possible.

In the present invention, the heating wire member made of copper nanowire is coated with nanosilver, which allows the components in the breath to be heated efficiently and shortens the time until the next detection is possible.

In addition, in the present invention, the heating wire member has a net-like mesh portion around the wound coil portion, which increases the degree to which the breath taken into the carbon nanostructure comes into contact with the heating wire member, efficiently heating the components in the breath and contributing to improved accuracy in detecting electrical resistance.

In the present invention, a breath sensor such as that described above is used to calculate blood glucose levels based on the detection results of changes in the electrical resistance of the carbon nanostructures, so blood glucose levels can be calculated with high accuracy, and the time until the next blood glucose level calculation can be performed can be shortened compared to conventional methods, improving ease of use.

1 is a schematic perspective view showing the appearance of a blood glucose measuring device according to an embodiment of the present invention. FIG. 2 is a block diagram of the main electric circuits of a control system of the blood glucose measuring device. 1 is a perspective view showing an overall appearance of a breath sensor unit according to an embodiment of the present invention; FIG. 2 is a schematic perspective view showing a disassembled state of the breath sensor unit. (a) is a cross-sectional oblique view of a cylindrical carbon nanosheet cut in half vertically to show the inside of the breath sensor, and (b) is a cross-sectional oblique view of the main parts of the annular insulating member cut vertically in the same manner to show the heating wire member inside. FIG. 2 is a schematic perspective view showing a state in which a heating line member is disposed inside a heat insulating member. FIG. 1 is a schematic perspective view showing a state in which a carbon nanosheet is wrapped around a heat insulating member having a heating line member disposed therein to form a cylindrical shape. FIG. 2 is a schematic perspective view showing a state in which a pair of electrodes is disposed inside a cylindrical carbon nanosheet. 1A is a front view of the breath sensor, FIG. 1B is a plan view of the breath sensor, and FIG. 1C is a cross-sectional view of the breath sensor in the front view of FIG. 1A taken along line AA. 4A and 4B show a state in which a breath sensor is held by a sensor holder, with FIG. 4A being a schematic perspective view and FIG. FIG. 2 is an electric circuit diagram showing an electrical connection state regarding a positive electrode and a negative electrode. FIG. 2 is a schematic diagram showing a situation in which exhaled air is taken into a breath sensor. 1 is a part of a graph comparing the blood glucose measurement results obtained by the blood glucose measuring device according to the present invention and a conventional device. 11 is the remaining portion of a graph comparing the blood glucose measurement results obtained by the blood glucose measuring device according to the present invention and a conventional device.

Figure 1 shows the appearance of a blood glucose measuring device 1, which is an example of an embodiment of the present invention. The blood glucose measuring device 1 of this embodiment is small and portable, with a pipe-shaped blowing section 3 protruding from the top surface 2a of a box-shaped housing 2, a display 5 that displays the measurement results exposed on the top surface 2a, and a power switch 4 located on one side surface 2b around the housing 2.

This blood glucose measuring device 1 is designed to measure the blood glucose level of a subject by having the subject hold the open tip 3a of the pipe-shaped blowing section 3 and blow (exhale) into it. Inside the blowing section 3 is placed a breath sensor unit 10, which plays a central role in the present invention, and the use of this breath sensor unit 10 makes it possible to measure blood glucose levels with higher accuracy than those disclosed in the above-mentioned Patent Document 1 or Patent Document 2, and is characterized by the fact that it shortens the time from the end of a measurement until the next measurement is possible. This will be explained in detail below.

Figure 2 shows a main electrical circuit block diagram of the control system in the blood glucose measuring device 1. As shown in this electrical circuit block diagram, part units related to the electrical circuit of the blood glucose measuring device 1 include the breath sensor unit 10 and display 5 described above, as well as a processor unit 6 and a transducer 7. The breath sensor unit 10 and the transducer 7 are connected by a first connection line d1 (the first connection line d1 is composed of multiple conductive lines), the transducer 7 and the processor unit 6 are connected by a second connection line d2, and the processor unit 6 and the display 5 are connected by a third connection line d3.

Each of these part units, such as the display 5, processor unit 6, transducer 7, and breath sensor unit 10, are arranged inside the housing 2 of the blood glucose measuring device 1 (the display screen of the display 5 is exposed from the top surface 2a of the housing 2). Although not shown in FIG. 2, the blood glucose measuring device 1 also has a battery 8 arranged inside the housing 2 for power supply, and power from the battery 8 is supplied to each of the above-mentioned part units through a power supply circuit (not shown), thereby applying a predetermined voltage to the breath sensor unit 10. This power supply circuit includes the power switch 4 shown in FIG. 1, and turning the power switch 4 on and off makes it possible to switch between a power supply state and a non-power supply state from the battery 8.

When a predetermined voltage is applied to the breath sensor unit 10 by turning on the power switch 4, an analog current is output from the breath sensor unit 10 to the transducer 7 through the first connection line d1. The transducer 7 amplifies and digitally converts the analog current input through the first connection line d1 to generate a converted signal that can be processed by the processor unit 5, and outputs the converted signal to the processor unit 6 through the second connection line d2.

The processor unit 6 detects the electrical resistance value related to the breath sensor unit 10 based on the input signal (input conversion signal) from the transducer 7, and calculates the blood glucose level based on the detected electrical resistance value. It is a unit in which the control unit 6a, memory 6b, RAM 6c, etc. are arranged on a printed circuit board.

The control unit 6a is a processor that functions as a means for performing various processes based on the programming contents of the program P stored in the memory 6b (the contents of the algorithm corresponding to the program). In this embodiment, the control unit 6a mainly performs the process of detecting the electrical resistance value based on the input signal from the transducer 7 as the electrical resistance detection means, the process of calculating the blood glucose level based on the value obtained by the electrical resistance detection process as the blood glucose level calculation means, and the process of displaying and outputting the calculated blood glucose level on the display 5 as the output means.

As described below, the breath of the subject is blown onto the breath sensor unit 10. When components in the subject's breath (e.g., components such as volatile organic compounds, specifically components such as acetone, ketones, and ethanol) adhere to the breath sensor unit 10, the electrical resistance value of the breath sensor unit 10 changes, and the control unit 6a detects this change in electrical resistance value based on the input signal from the transducer 7.

Specifically, the control unit 6a detects the electrical resistance value when the power switch 4 is turned on and power supply is started, and when the subject's breath is not being blown into the sensor, and also detects the electrical resistance value after the breath is blown into the sensor. The degree of change in the electrical resistance value is determined according to the amount of components in the breath that adhere to the breath sensor unit 10, and the greater the amount of components that adhere, the greater the degree of change.

In addition, in the process of calculating the blood glucose level based on the value obtained in the process of detecting the changed electrical resistance, the control unit 6a first detects the concentration of components in the exhaled breath from the detected electrical resistance value, then converts the detected concentration of components into a blood glucose level based on a predetermined conversion formula, and finally calculates the blood glucose level of the subject who blew in the exhaled breath. The predetermined conversion formula used in this calculation is either stored in advance in the memory 6b or is included in the program P.

In this embodiment, the concentration of components in the breath related to blood glucose levels, mainly acetone, is detected in ppm (parts per million) units. Typically, when the subject is a non-diabetic patient, the detected component concentration is approximately 0.3 to 0.9 ppm. On the other hand, when the subject is a diabetic patient, the detected component concentration is generally a value exceeding 0.9 ppm. Note that in this embodiment, it is possible to calculate values up to approximately 10 ppm (and the control unit 6a may also be able to calculate the concentration in detail in units of several ppb (parts per billion)).

When the control unit 6a detects the concentration of components including acetone, as described above, it substitutes the detected numerical value of the concentration of the components into the predetermined conversion formula described above to calculate the blood glucose level (glucometer count). Then, in order to display the calculated blood glucose level on the display 5, the control unit 6a generates measurement result information including the blood glucose level and outputs it to the display 5 via the third connection line d3. The control unit 6a also performs a process of temporarily storing the calculated blood glucose level, the detected concentration of the components, the electrical resistance value, etc. in the RAM 6c.

In addition, immediately after the power switch 4 is turned on, the control unit 6a in this embodiment performs a process of counting the time required for the heating wire member 14 to generate heat up to a predetermined temperature. In this embodiment, it determines whether the reference time stored in advance in the memory 6b is reached, and if it determines that the reference time has been reached, it counts up and starts the above-mentioned process of detecting the electrical resistance value. Also, while the control unit 6a is counting the time, it outputs information indicating the count status to the display 5.

The display 5 is a display panel such as a liquid crystal or organic electroluminescence display, and when it receives information output from the control unit 6a via the third connection line d3, it displays the received information on the display screen. This allows the subject, or user, to easily know his or her own blood glucose level by viewing the display 5. Next, the breath sensor unit 10, which is the core of the present invention, will be described in detail.

Fig. 3 shows the overall appearance of the breath sensor unit 10 according to this embodiment, and Fig. 4 shows an exploded view of the same. The breath sensor unit 10 according to this embodiment is mainly composed of a sensor holder 30, a breath sensor 11, and a sensor cover 20. Note that the X-axis shown in Figs. 3 and 4 indicates one direction on a horizontal plane, the Y-axis indicates a direction perpendicular to the X-axis on the same horizontal plane, and the Z-axis indicates a direction perpendicular to the X-axis and Y-axis. Thus, specifically, the X-axis represents the width direction of the breath sensor unit 10, the Y-axis represents the depth direction of the breath sensor unit 10, and the Z-axis represents the height direction of the breath sensor unit 10 (the orientations of the X, Y, and Z-axes are the same in the other figures).

The sensor holder 30 is a member for holding the breath sensor 11, and has a donut-shaped holder body 31 and a total of six conductive pins, first to sixth, 32a, 32b, 33a, 33b, 34a, and 34b, that penetrate the holder body 31 in the height direction (Z-axis direction).

The holder body 31 is a nickel-plated copper member with a stepped upper surface 31a and a flat lower surface 31b, and a hollow portion 31c that penetrates in the height direction (Z-axis direction) in the center. In this embodiment, the thickness (height in the Z-axis direction) of the holder body 31 at the outer periphery is set to approximately 12 mm, and the inner diameter of the hollow portion 31c of the holder body 31 is set to a value corresponding to the outer diameter of the breath sensor 11, so that the breath sensor 11 can be fitted into and held in the hollow portion 31c.

The first to sixth

conductive pins

32a, 32b, 33a, 33b, 34a, 34b penetrate from the stepped upper surface 31a to the lower surface 31b of the holder body 31, and each of the six conductive pins 32a to 34b is a conductive nickel-plated pin member and is arranged at intervals in the circumferential direction of the holder body 31 in a plan view (see FIG. 10(b)). The first and second

conductive pins

32a, 32b are for connection to the heating wire member 14 included in the breath sensor 11, the third and fourth

conductive pins

33a, 33b are for connection to the positive electrode 16 included in the breath sensor 11, and the fifth and sixth

conductive pins

34a, 34b are for connection to the negative electrode 17 included in the breath sensor 11.

The sensor cover 20 is a cover for covering and protecting the breath sensor 11 held in the holder body 31, and has a cover portion 21 protruding from an annular flange portion 22. The cover portion 21 is a mesh member made of stainless steel mesh, and has a mesh size sufficient to allow breath to pass through. The annular flange portion 22 is also formed to fit into the step on the upper surface 31a of the sensor holder 30 described above.

The breath sensor 11 is the main part of the breath sensor unit 10 and is used to detect the concentration of components in the breath, and is directly used to detect changes in electrical resistance caused by the adhesion of components in the breath. The breath sensor 11 has a tubular (cylindrical) overall appearance, with a total of six lead wires T1 to T4, H1, and H2 extending outwards from the periphery.

The portion that constitutes the tubular (cylindrical) appearance of the breath sensor 11 is made of a carbon nanostructure, and in this embodiment, a carbon nanosheet 12 with excellent electrical conductivity is used as the carbon nanostructure. The carbon nanosheet 12 has numerous nano-sized depressions on its sheet-like surface, and these depressions make it easy for the components in the breath to adhere to it. In addition, the carbon nanosheet 12 (carbon nanostructure) has the property that its electrical properties change when components contained in the breath adhere to it; specifically, the electrical resistance changes, and the degree of this change in electrical resistance increases as more components adhere to it.

As also shown in FIG. 5(a), the breath sensor 11 has a ring-shaped insulating member 13 and a pair of electrodes 15 arranged inside the carbon nanosheet 12. Specifically, the ring-shaped insulating member 13 is arranged near the upper end of the breath sensor 11 in the height direction (Z-axis direction) (the side of the upper end 12a of the carbon nanosheet 12), while the pair of electrodes 15 are arranged near the lower end of the breath sensor 11 in the height direction (Z-axis direction) (the side of the lower end 12b of the carbon nanosheet 12).

As shown in Figures 5 and 6, the insulating member 13 is a ring-shaped (tubular) member having a predetermined height, and in this embodiment, a ceramic member is used (for example, a tubular member formed by stacking multiple ceramic layers). The insulating member 13 has a fullerene layer 18 formed on its inner peripheral surface 13b. The size of the insulating member 13 in this embodiment is set to approximately 16 mm in the radial dimension (outer diameter) and approximately 8 mm in height.

The fullerene layer 18 is formed by mixing powdered fullerene with a solvent or the like to a predetermined viscosity (for example, a paste) and applying (spraying) it to the inner circumferential surface 13b of the heat insulating member 13. The fullerenes used are basically types C60 and C70, but types C76, C78, C82, C84, C90, and C96 can also be used.

Also, as shown in Figures 5(b), 6, 9(b), 10(b), etc., a heating wire member 14 is disposed inside the insulating member 13. The heating wire member 14 is for heating the components in the breath blown in by the subject, and is composed of wire (heat wire). Specifically, in order to generate more heat, the heating wire member 14 of this embodiment has a coil section 14a wound with wire at its center, and a mesh section 14b made of wire woven in a mesh pattern is integrally formed around the coil section 14a.

The coil portion 14a is wound at a pitch (spacing) that does not prevent the passage of exhaled breath components (gas components), and the mesh size of the mesh portion 14b is set to a dimension that does not prevent the passage of exhaled breath components (gas components). The outer peripheral contour of the coil portion 14a is circular, and the radial dimension is set to a value that corresponds to the inner diameter dimension of the insulating member 13 described above, so that the heating wire member 14 can be fitted and positioned inside the insulating member 13.

Furthermore, the heating wire member 14 of this embodiment uses copper nanowires as the wire material (heat wire), and the surface of the copper nanowires is coated with nanosilver by electroplating. The copper nanowires are produced through a process of reducing Cu(OH) ² with a reducing agent (hydrazine _N2H4 ). For example, the copper nanowires are obtained by performing a process of reducing Cu(OH) ² with a reducing agent (hydrazine _N2H4 ₎ in an aqueous solution containing sodium hydroxide (NaOH) and _{ethylenediamine} .

More specifically, 18 liters of sodium hydroxide (NaOH), 0.36 mol of Cu(OH) ² , 135 ml of EDA, and 18 ml (35 wt%) of hydrazine are placed in a 20 liter reactor and heated at 80° C. for 30 minutes to reduce Cu2+ to metallic copper at a rate of 100%, thereby obtaining copper nanowires. The surface of the copper nanowires thus obtained is coated with nanosilver by electroplating, but in this embodiment, the entire surface of the copper nanowires is not coated with nanosilver, but rather some uncoated areas are left uncoated, so that an oxidation reaction occurs in the uncoated areas during heating.

The heating wire member 14 as described above has heating leads H1 and H2 extending from the outer periphery along the longitudinal direction of the coil portion 14a (points corresponding to both ends of the diameter that pass through the coil portion 14a). These leads H1 and H2 are electrically connected to the wire that constitutes the heating wire member 14, and when a current from the battery 8 is passed through the leads H1 and H2 to the heating wire member 14, the heating wire member 14 generates heat, reaching approximately 200°C (note that in order to accurately detect changes in electrical resistance, it is preferable for the heating wire member 14 to generate heat to at least approximately 140°C).

As shown in Figures 5(a), 8, 9(c), etc., a pair of electrodes 15 arranged on the side of the lower end 12b (the other end) of the carbon nanosheet 12 has a positive electrode 16 and a negative electrode 17, which are small pieces (small plate-shaped) of material. In this embodiment, in order to ensure a certain level of conductivity, the positive electrode 16 and the negative electrode 17 contain gold nanoparticles. In addition, positive electrode lead wires T1 and T2 are connected to the outer surface 16a of the positive electrode 16, and negative electrode lead wires T3 and T4 are connected to the outer surface 17a of the negative electrode 17. Platinum wires are used for these lead wires T1 to T4 in order to ensure a certain level of conductivity.

The electrical circuit diagram shown in Figure 11 shows the electrical connection status of the positive electrode 16 and negative electrode 17. The power switch 4 and battery 8 are connected in series, and the power switch 4 is connected to the positive electrode 16, and the negative electrode of the battery 8 is connected to the negative electrode 17. A carbon nanosheet 12 is interposed between the positive electrode 16 and the negative electrode 17. When the power switch 4 is turned on, a predetermined voltage is applied between the positive electrode 16 and the negative electrode 17, and a current flows from the positive electrode 16 to the negative electrode 17 through the carbon nanosheet 12.

The current flowing in this manner is output to the transducer 7 as described above. Although not shown in the electrical circuit diagram of FIG. 11, the battery 8 is also electrically connected to the heating wire member 14 described above, and power supply from the battery 8 to the heating wire member 14 can be switched by turning the power switch 4 on and off. Next, the steps of the manufacturing process for the breath sensor 11 described above will be described.

First, as shown in FIG. 6, the heating wire member 14, which has been prepared in advance, is inserted into the heat insulating member 13 from the lower end 13c. The height at which the heating wire member 14 is placed is preferably in the middle of the heat insulating member 13 in the height direction (Z-axis direction) to ensure stable placement. The lead wires H1 and H2 extending from the heating wire member 14 placed inside the heat insulating member 13 are pulled outward from the lower end 13c of the heat insulating member 13.

Next, as shown in FIG. 7, the rectangular carbon nanosheet 12 is wrapped around the outer peripheral surface 13a of the heat insulating member 13 to form a tube (cylindrical shape). To maintain this tube shape, one vertical side 12c (side along the Z-axis direction) of the carbon nanosheet 12 is overlapped with the other vertical side 12d and bonded together with a conductive adhesive. In order to prevent the heat insulating member 13 and the carbon nanosheet 12 from shifting, it is preferable to apply an adhesive to the periphery of the heat insulating member 13 and bond it to the carbon nanosheet 12. In this case, a heat-resistant adhesive is used. The lead wires H1 and H2 extending from the heating wire member 14 are passed through the carbon nanosheet 12 and taken out to the outside.

Then, as shown in FIG. 8, a pair of electrodes 15 are inserted into the carbon nanosheet 12 from the lower end 12b side of the cylindrically formed carbon nanosheet 12, and arranged in a state where they are electrically connected to the carbon nanosheet 12. The positive electrode 16 and negative electrode 17 of the electrodes 15 arranged inside in this manner are fixed in a state where they are in contact with the inner surface 12e of the carbon nanosheet 12 (see FIG. 7 and FIG. 9(c)).

Specifically, as shown in FIG. 9(c), a conductive adhesive is applied to the left and right

vertical side portions

16b, 16c (see FIG. 8, sides parallel to the Z-axis direction) on the outer surface 16a of the positive electrode 16, and the left and right

vertical side portions

16b, 16c are pressed against and adhered to the inner surface 12e of the carbon nanosheet 12, thereby fixing the positive electrode 16 to the inner surface 12e of the carbon nanosheet 12. In addition, the left and right

vertical side portions

17b, 17c (with the conductive adhesive applied) on the outer surface 17a of the negative electrode 17 are pressed against and adhered to the inner surface 12e of the carbon nanosheet 12 at a position opposite the positive electrode 16, thereby fixing the negative electrode 17 to the inner surface 12e of the carbon nanosheet 12.

By fixing the positive electrode 16 and the negative electrode 17 to the carbon nanosheet 12 as described above, the positive electrode 16 and the negative electrode 17 are fixed in a state of electrical conduction (connection) with the carbon nanosheet 12. Note that the lead wires T1, T2 extending from the outer surface 16a of the positive electrode 16 and the lead wires T3, T4 extending from the outer surface 17a of the negative electrode 17 penetrate the carbon nanosheet 12 and are taken out to the outside, similar to the lead wires H1, H2 of the heating wire member 14 described above. The breath sensor 11 is completed through the manufacturing process described above.

The completed breath sensor 11 is fixed by fitting it from below into the hollow portion 31c of the sensor holder 30 described above (see Figure 4). In order to ensure a firm fixation, it is preferable to apply adhesive to the inner surface of the hollow portion 31c in advance and use the adhesive to fix the breath sensor 11 to the hollow portion 31c of the sensor holder 30. In addition, when fixing, the breath sensor 11 is oriented in the circumferential direction so that the lead wires H1 and H2 extending from the periphery of the breath sensor 11 (carbon nanosheet 12) face the first and second

conductive pins

32a and 32b of the sensor holder 30.

Once the breath sensor 11 has been fixed, the lead wires H1, H2, T1-T4 are then connected to the upper ends of the first through sixth

conductive pins

32a, 32b, 33a, 33b, 34a, and 34b by soldering or the like (see Figures 9(a) and 9(b)). Finally, the sensor cover 20 is attached so as to cover the breath sensor 11 and the upper surface 31a of the sensor holder 30 (holder body 31), completing the breath sensor unit 10 (see Figures 3 and 4).

The completed breath sensor unit 10 is electrically connected and then placed inside the blood glucose measuring device 1 shown in FIG. 1. The lower ends of the first and second

conductive pins

32a and 32b are connected to a power supply circuit with the battery 8 placed inside the blood glucose measuring device 1, thereby allowing current to flow to the heating wire member 14, thereby enabling heating by the heating wire member 14. In the circuit block shown in FIG. 2, the multiple conductive wires constituting the first connection line d1 for connection to the transducer 7 are connected to the lower ends of the third conductive pin 33a and the fifth conductive pin 34a, respectively, and the lower ends of the fourth conductive pin 33b and the sixth conductive pin 34b are connected to the positive and negative sides of the battery 8, respectively, as shown in the electrical circuit diagram in FIG. 11, to perform electrical circuit connection.

Once the electrical connections are complete, the breath sensor unit 10 is positioned so that the sensor cover 20 fits inside the pipe-shaped blowing section 3 that protrudes from the top surface 2a of the housing 2 of the blood glucose measuring device 1. With the breath sensor unit 10 positioned in this way, the Z-axis direction of the breath sensor unit 10 is aligned with the protruding direction of the blowing section 3.

By positioning the breath sensor unit 10 as described above, the breath blown into the open tip 3a of the blowing section 3 is taken in through an opening formed on the side (one end side) of the upper end 12a of the carbon nanosheet 12 of the breath sensor 11. Therefore, the opening formed on the upper end 12a of the carbon nanosheet 12 in the breath sensor 11 functions as the breath intake 11a (see Figures 4, 12, etc.).

Next, the usage of the blood glucose measuring device 1 will be described. The subject (user) first turns on the power switch 4. When the power switch 4 is turned on, power supply (voltage application) from the battery through the power supply circuit is started, the processor unit 6 and other components included in the circuit block shown in FIG. 2 are started, heating is started by the heating wire member 14, and a predetermined voltage of 1.8 to 2.2 V is applied to the electrode 15 (between the positive electrode 16 and the negative electrode 17) of the breath sensor 11, causing a stable current to flow through the carbon nanosheet 12 between the positive electrode 16 and the negative electrode 17.

When the control unit 6a of the processor unit 6 is started, it performs a timing process until the heating wire member 14 reaches a temperature sufficient for the detection process (for example, about 200°C), and also performs a process of outputting timing information indicating the status during timing (time count status) to the display 5. As a result, the time count status is displayed on the display screen of the display 5, and the subject (user) waits until the time counts up.

The control unit 6a determines whether the measured time reaches the reference time stored in the memory 6b. The reference time can be any time within the range of approximately 60 to 180 seconds, and in this embodiment, 70 seconds is used as the reference time.

When the time reaches a reference time, the control unit 6a starts counting up and performs a series of processes such as the above-mentioned electrical resistance detection process, component concentration detection process, and blood glucose calculation process, and outputs numerical information indicating the calculated blood glucose level to the display 5. The number displayed on the display screen of the display 5 after counting up from powering on is based on the components contained in normal air before exhalation, and generally shows a value of about 60 to 70 (the unit of blood glucose level is mg/dl. The same applies below, and unit notation is omitted). In the blood glucose measuring device 1 of this embodiment, when the number displayed on the display screen is 70 or less, it is considered to be in a usable (detectable) state.

Therefore, when the display screen switches from a counting state to numerical information, the subject (user) checks whether the displayed number is 70 or less, and if the displayed number is 70 or less, holds the blowing part 3 in his/her mouth and blows into it. Note that if the number displayed on the display screen exceeds 70, the subject (user) waits until the displayed number becomes 70 or less before blowing into it.

Figure 12 shows the state in which breath (exhaled air F) blown into the blowing section 3 is taken into the exhaled air sensor 11 built into the exhaled air sensor unit 10. As shown in Figure 12, the exhaled air F flows into the sensor from the open intake port 11a and passes through the heating wire member 14 arranged inside the carbon nanosheet 12. When passing through this heating wire member 14, the components contained in the exhaled air F are heated, promoting various reactions such as oxidation, activating the electrons in the components, and the activated components adhere to the carbon nanosheet 12, making it easy for the electrical resistance of the carbon nanosheet 12 between the positive electrode 16 and the negative electrode 17 to which a voltage is applied to change significantly.

Specifically, the copper nanowires constituting the heating wire member 14 have some uncoated surfaces, and in these uncoated areas, heating causes an oxidation reaction of the copper components, generating copper oxide (CuO). When components in the exhaled breath pass through the heating wire member 14, they react with this copper oxide (CuO). For example, in the case of acetone ( _CH3COCH3 ), which is a component in the exhaled breath, a reaction occurs between the copper oxide and acetone _.

Acetone ( _CH3COCH3 ) is decomposed (pyrolyzed) into components such as ketene ( _CH2CO ) and _methane ( _CH4 ), and the components produced by such a reaction adhere to the inner surface 12e of the carbon nanosheet 12 of the breath sensor 11, causing a change in the electrical resistance of the breath sensor 11 (carbon nanosheet 12).

As mentioned above, the components of the breath taken into the breath sensor 11 are heated by the heating wire member 14, which makes it easier for the electrical resistance to change quickly. However, if too much heat is transmitted from the heating wire member 14 to the carbon nanosheet 12, it will affect the change in electrical resistance caused by the adhesion of the breath components, and there is a concern that this will worsen the accuracy of detecting the electrical resistance based on the adhesion of the breath components.

However, in the breath sensor 11 used in this embodiment, the heating wire member 14 is disposed inside the insulating member 13, and the insulating performance of the insulating member 13 is reinforced by the fullerene layer 18 on the inner surface 13a, so that the heat generated by the heating wire member 14 is prevented from being transmitted to the carbon nanosheet 12 and affecting the electrical resistance value of the carbon nanosheet 12 as much as possible.

Furthermore, among the components taken into the breath sensor 11 (carbon nanosheet 12), those not necessary for detecting electrical resistance are adsorbed or absorbed by the fullerene layer 18 on the inner surface 13a of the insulating member 13, so the change in electrical resistance of the carbon nanosheet 12 depends mainly on the components in the breath that are related to the change in electrical resistance being adsorbed to the carbon nanosheet 12. As a result, the blood glucose measuring device 1 of the present invention makes the change in electrical resistance due to the components in the breath more noticeable, making it possible to detect the change in electrical resistance due to the components in the breath with high accuracy.

The blood glucose measuring device 1 (control unit 6a) then detects the concentration of the components contained in the breath taken into the breath sensor 11 based on the calculation results regarding the change in electrical resistance described above, and the final blood glucose level is calculated based on the detected concentration, with the final calculated blood glucose level changing according to the changed electrical resistance. The blood glucose level thus changing is displayed on the display screen of the blood glucose measuring device 1, so that the subject (user) can ascertain their own blood glucose level by simply blowing a breath (exhaled air) into the blood glucose measuring device 1 and viewing the numerical value displayed on the display screen.

In addition, in the case of subjects with diabetes or a tendency to develop diabetes, the number (blood glucose level) displayed on the display screen after breathing (exhalation) will change significantly from the number displayed on the display screen before breathing (exhalation).

When the calculated blood glucose level reaches its peak value through the above-mentioned process, that value is held and continues to be displayed on the display screen of the blood glucose measuring device 1, and the blood glucose measurement is completed in this state.

After the measurement is complete, the subject (user) turns off the power switch 4, which resets the calculated blood glucose level. Furthermore, when the next detection is to be performed, the subject (user) turns on the power switch 4. In this case, as in the case described above, the control unit 6a performs timing processing until the reference time (e.g., 70 seconds) is reached, and when the timing processing ends, the value calculated at that time (a value corresponding to the blood glucose level) is displayed on the display screen.

In this case, if the power switch 4 is turned on before sufficient time has passed since the completion of the previous measurement, the number displayed on the display screen will not fall below 70 due to the influence of floating components remaining inside the breath sensor 11, and it will be necessary to wait until the breath is blown into the sensor until it becomes capable of detection and measurement.

The blood glucose measuring device 1 according to the present invention is also characterized by the fact that it quickly recovers to a state where the next measurement is possible after the previous measurement is completed. In other words, after the measurement is completed, the changed electrical resistance value of the carbon nanosheet 12 is slow to return to normal due to residual components and moisture components floating inside the breath sensor 11 (carbon nanosheet 12), and as a result, it takes time for the blood glucose level to fall below 70.

However, as described above, the blood glucose measuring device 1 of the present invention forms a fullerene layer 18 on the inner surface 13b of the insulating member 13, and the fullerenes that make up this fullerene layer 18 have the property of efficiently adsorbing and absorbing components in gas. As a result, the remaining components and moisture components floating inside the breath sensor 11 are adsorbed and absorbed by the fullerene layer 18, so that the blood glucose level smoothly settles below 70 after the measurement is completed. This allows the blood glucose measuring device 1 (breath sensor 11) of the present invention to recover in a short time to a state where the next detection and measurement are possible. Note that the components attached to the carbon nanosheet 12 will naturally evaporate and be removed.

In experiments conducted by the applicant, it was confirmed that without the fullerene layer 18, it took at least about 10 minutes (about 600 seconds) after the completion of a measurement for the sensor to recover to a state where the next measurement was possible, but with the fullerene layer 18, the recovery time for the sensor to recover to a state where the next detection and measurement was possible was reduced to about 1 to 5 minutes.

Figures 13 and 14 are tables showing the results of an experiment comparing blood glucose levels calculated using the blood glucose measuring device 1 of the present invention with blood glucose levels calculated using a conventional blood sampling device with a test kit for a total of 48 subjects (subjects No. 1 to 48). In this experiment, for each subject, the blood glucose measuring device 1 of the present invention and the conventional device were used at roughly the same time to calculate blood glucose levels with each device (specifically, the blood glucose level was calculated first with the blood glucose measuring device 1, and then immediately with the conventional device).

The average difference in the comparison results for the total of 48 people shown in Figures 13 and 14 is "6.17 (rounded to two decimal places)," with the largest difference being "14" for subject No. 32 (result for the conventional device was "306" and result for the device of the present invention was "292"), and the smallest difference being "0" for subject No. 28 (results for both the conventional device and the device of the present invention were "100"). From the tables shown in Figures 13 and 14, it can be seen that the blood glucose measuring device 1 of the present invention is a useful assumption that ensures sufficient measurement accuracy.

It is generally known that the higher the blood glucose level, the greater the error in the measurement results. In the comparison result tables shown in Figures 13 and 14, it can be seen that subjects with higher measured blood glucose levels have a larger difference between the two (for example, subjects No. 19, 27, 32, and 47 had blood glucose levels over 200, so the difference between the two is also large. Also, a blood glucose level over 200 is generally considered to be diabetic).

As described above, the blood glucose measuring device 1 equipped with the breath sensor 11 according to the present invention is useful and easy to use for measuring blood glucose levels, since it can measure blood glucose levels with high accuracy and requires a short time to recover from the completion of a blood glucose measurement until the next measurement is possible. Note that the blood glucose measuring device 1 equipped with the breath sensor 11 according to the present invention is not limited to the above-mentioned form, and various modified examples are envisioned.

For example, in the above description, a carbon nanosheet 12 is used around the breath sensor 11, but other carbon nanostructures may be used as long as they have the property of changing electrical resistance when components contained in breath adhere to them (for example, a tubular body may be formed around the breath sensor 11 using carbon nanotubes). In addition, the tubular body that forms the periphery of the breath sensor 11 is not limited to a cylindrical shape, and tubular shapes with polygons (square, pentagon, hexagon, heptagon, octagon, etc.) can also be used.

In addition, while it has been described that the negative electrode 17 in the pair of electrodes 15 contains gold nanoparticles (negative electrodes using gold nanoparticles are easy to manufacture), it is also possible to use other materials that contain fullerenes (C60, C70, etc.) that have excellent conductive properties in order to improve conductivity. As a form that contains fullerenes, it is possible to form a negative electrode by mixing graphite oxide and fullerenes. By using such a negative electrode 17 that contains fullerenes, it becomes easier to detect changes in electrical resistance with high accuracy.

On the other hand, when there is no need to reduce the time required to recover to a detectable state, it is possible to omit the fullerene layer 18 formed on the inner surface 13b of the insulating member 13. Furthermore, when the external diameter dimensions of the breath sensor 11 are set in a way that the sensor is not significantly affected by heat generated by the heating wire member 14, it is also possible to omit the insulating member 13.

Furthermore, the heating wire member 14 is not limited to the configuration shown in Figures 5(b) and 6 (a configuration in which a mesh portion 14b is formed around a coil portion 14a), but may be, for example, a configuration in which the mesh portion 14b is omitted and only the coil portion 14a is provided (such as a configuration in which multiple coil portions 14a are arranged in parallel), or conversely, a configuration in which the coil portion 14a is omitted and only the mesh portion 14b is provided.

Furthermore, the coating of the heating wire member 14 is not limited to nanosilver, but other nano coating materials or coating materials of a completely different system may be used, and the coated wire member is not limited to copper nanowire, but any material that generates heat when electricity is passed through it can be used. Furthermore, depending on the material used, the coating with a coating material such as nanosilver may be omitted.

Furthermore, the above description of the various processing contents by the program P used in the blood glucose measuring device 1 is just one example, and it is of course possible to define or add other processing contents. For example, according to the comparison table of experimental results shown in Figures 13 and 14, it can be seen that when the measured blood glucose level exceeds 200, there is a tendency for the difference from the measurement results by conventional devices to become larger (the error tends to become larger), so it is possible to add programming contents to the program P based on an algorithm (an algorithm that performs error dispersion, etc.) that corrects the measured blood glucose level when the measured blood glucose level exceeds 200.

The present invention makes it possible to measure blood glucose levels with high accuracy simply by blowing into the device, and also shortens the recovery time from one measurement to the next, making it suitable for use by people with diabetes or a tendency toward diabetes to measure their blood glucose levels on a daily basis.

REFERENCE SIGNS LIST 1 Blood glucose measuring device 2 Housing 3 Blowing section 4 Power switch 5 Display 6 Processor unit 6a Control section 10 Breath sensor unit 11 Breath sensor 11a Intake port 12 Carbon nanosheet 13 Heat insulating member 14 Heating wire member 15 Electrode 16 Positive electrode 17 Negative electrode 18 Fullerene layer 20 Sensor cover 30 Sensor holder P Program

Claims

A breath sensor having a carbon nanostructure that has a characteristic that its electrical resistance changes when a component contained in breath adheres to the carbon nanostructure,
The carbon nanostructure is formed in a cylindrical shape,
A heating wire member disposed inside the carbon nanostructure;
a pair of electrodes electrically connected to the carbon nanostructure;
An breath sensor characterized in that an opening formed on one end side of the carbon nanostructure is used as an intake port for breath.
a ring-shaped heat insulating member disposed inside the carbon nanostructure;
2. The breath sensor according to claim 1, wherein the heating wire member is disposed inside the heat insulating member.
The breath sensor according to claim 2, wherein a fullerene layer is formed on the inner peripheral surface of the annular insulating member.
The breath sensor of claim 1, wherein the negative electrode of the pair of electrodes contains fullerene.
The breath sensor according to any one of claims 1 to 4, wherein the heating wire member is formed of copper nanowires coated with nanosilver.
The breath sensor according to claim 2, wherein the heating wire member has a wound coil portion and a net-like mesh portion formed around the coil portion.
The breath sensor according to any one of claims 1 to 4,
An electrical resistance detection means for detecting a change in the electrical resistance of the carbon nanostructure included in the breath sensor;
a blood glucose level calculation means for calculating a blood glucose level based on a detection result of the electrical resistance detection means;
and an output means for outputting a calculation result of the blood glucose level calculation means.
The blood glucose measuring device according to claim 7, wherein the heating wire member included in the breath sensor is formed of copper nanowire coated with nanosilver.
The blood glucose measuring device according to claim 7, wherein the heating wire member has a wound coil portion and a net-like mesh portion formed around the coil portion.