JP2008229084A - Respiratory sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a respiratory sensor that easily and accurately detects the respiratory conditions of a subject by placing no burden upon the subject. <P>SOLUTION: A respiratory sensor 2 comprises an elastomer, a spherical electroconductive filler placed within the elastomer in nearly a single particle state and at a high filling rate, an elastically deformable sensor body 20 whose electric resistance increases with the increase of its elastic deformation, and electrodes A and B connected with the sensor body 20 and giving an electric resistance output to the sensor body 20. The sensor body 20 elastically deforms following the respiratory bodily movements of the subject 9 and detects his or her respiratory conditions from the time changes of its electric resistance based on its elastic deformation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a respiratory sensor capable of detecting a respiratory state of a subject.

  For example, in order to detect and treat apnea syndrome, it is necessary to measure the respiratory state. Usually, the measurement of a respiratory state is performed by attaching instruments, such as a mask and a tube, to a subject's nostril or oral cavity. However, according to this method, the subject feels stuffy and pressured by wearing the instrument, and the burden on the subject is large. In addition, the subject becomes conscious of the instrument, and the normal breathing state is difficult to be reproduced. On the other hand, in patients with athetoid cerebral palsy, symptoms such as inability to breathe due to lesions in the brain's motor center appear. Such a patient's breathing state cannot be correctly grasped by a spirogram (breathing curve) when consciously breathing.

For example, as a method for measuring a respiratory state with less burden on the subject, Patent Document 1 introduces a clothing type sensor that detects a respiratory state from increase / decrease in the length of the circumference of the trunk due to respiration. Further, Patent Document 2 introduces an apnea detection device that incorporates a pressure-sensitive pipe in a mat and detects apnea from a pressure change caused by the movement of the body of a subject lying on the mat.
JP-A-10-99299 JP 2000-107154 A

  According to the clothes type sensor of the above-mentioned patent document 1, since it is necessary to match clothes with a physique of a subject, adjustment of clothes at the time of measurement is complicated. In addition, the burden is placed on the subject due to the weight of clothes, discomfort, and the tightness of the torso. Furthermore, during exercise such as walking, information other than breathing becomes dominant, and it is difficult to accurately measure the breathing state.

  On the other hand, according to the apnea detection device of Patent Document 2, measurement can be performed only in a state where the subject is laid down. In addition, it is easily affected by posture changes such as turning over and other body movements, and it is difficult to accurately measure the respiratory state. In addition, the apparatus is large and the manufacturing cost is high.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the respiration sensor which can detect a respiratory state simply and correctly, without putting a burden on a subject.

  (1) The respiratory sensor of the present invention has an elastomer and a spherical conductive filler that is blended in the elastomer in a substantially single particle state and at a high filling rate. An elastically deformable sensor main body having an increased resistance and an electrode connected to the sensor main body and capable of outputting the electric resistance, the sensor main body accompanying the movement of the body of the subject due to respiration The respiratory state of the subject can be detected from the time-dependent change of the electrical resistance based on the elastic deformation of the sensor body (corresponding to claim 1).

  The sensor main body (hereinafter referred to as “sensor main body in the present invention” as appropriate) in the respiration sensor of the present invention is elastically deformable and has an elastomer and a spherical conductive filler. In this specification, “elastomer” includes rubber and thermoplastic elastomer. The conductive filler is blended in the elastomer in a substantially single particle state and with a high filling rate. Here, the “substantially single particle state” means that 50% by weight or more when the total weight of the conductive filler is 100% by weight exists not in the form of aggregated secondary particles but in the form of single primary particles. It means that Further, “high filling rate” means that the conductive filler is blended in a state close to closest packing.

  As described above, when the conductive filler is blended in a substantially single particle state and at a high filling rate, a three-dimensional conductive path is formed by contact between the conductive fillers via the elastomer component. Therefore, the sensor body in the present invention has high conductivity in a state where no load is applied (hereinafter, referred to as “no-load state” as appropriate), in other words, in a natural state where the sensor body is not elastically deformed. Note that “elastic deformation” in this specification includes all deformation due to compression, extension, bending, and the like.

  For example, a conventional pressure-sensitive conductive resin has a large electric resistance in an uncompressed state, and the electric resistance decreases when deformed by compression. This can be explained from the configuration of the pressure-sensitive conductive resin as follows. That is, the pressure sensitive conductive resin is composed of a resin and a conductive filler blended in the resin. Here, the filling rate of the conductive filler is low. For this reason, the conductive fillers are separated from each other in a no-load state. That is, in the no-load state, the electric resistance of the pressure sensitive conductive resin is large. When a load is applied and the pressure-sensitive conductive resin is deformed, the conductive fillers are brought into contact with each other to form a one-dimensional conductive path. This reduces the electrical resistance.

  On the other hand, the electrical resistance of the sensor body according to the present invention increases as the amount of elastic deformation increases. The reason is considered as follows. FIG. 1 and FIG. 2 show changes in the conductive path of the sensor body according to the present invention before and after applying a load as a model. However, what is shown in FIGS. 1 and 2 is an example of the sensor main body, and the sensor main body, the shape and material of the conductive filler in the present invention are not limited at all.

  As shown in FIG. 1, in the sensor main body 100, most of the conductive fillers 102 are present in the state of primary particles in the elastomer 101. Moreover, the filling rate of the conductive filler 102 is high, and it is blended in a state close to closest packing. Thereby, in a no-load state, a three-dimensional conductive path P is formed in the sensor body 100 by the conductive filler 102. Therefore, in the no-load state, the electrical resistance of the sensor body 100 is small. On the other hand, as shown in FIG. 2, when a load is applied to the sensor main body 100, the sensor main body 100 is elastically deformed (the dotted line frame in FIG. 2 indicates the no-load state in FIG. 1). Here, since the conductive filler 102 is blended in a state close to closest packing, there is almost no space where the conductive filler 102 can move. Therefore, when the sensor main body 100 is elastically deformed, the conductive fillers 102 repel each other, and the contact state between the conductive fillers 102 changes. As a result, the three-dimensional conductive path P collapses and the electrical resistance increases.

  For example, when attention is paid to the movement of the chest accompanying breathing of the subject, the diaphragm is lowered and the chest is inflated during inhalation. Along with this, the chest surface is displaced so as to increase the curvature. On the other hand, during expiration, the diaphragm rises and the chest contracts. Along with this, the chest surface is displaced so that the curvature becomes small. Therefore, for example, when the respiration sensor of the present invention including the sensor main body is arranged on the chest surface of the subject, the sensor main body is elastically deformed by the displacement of the chest surface accompanying respiration. When the sensor body is elastically deformed, the electrical resistance output from the electrode changes. Based on the change over time in the electrical resistance of the sensor body, it is possible to detect the breathing cycle and breathing depth of the subject, that is, the breathing state. Here, “electric resistance can be output” means that electric resistance can be output directly or indirectly. That is, not only the case where the electrical resistance is directly output from the electrode but also the case where the other electrical quantity related to the electrical resistance such as voltage or current is output.

  Thus, according to the respiration sensor of the present invention, it is possible to easily detect the respiration state by disposing the respiration sensor at the site that is displaced by the respiration of the subject. That is, it is not necessary to attach a device such as a mask or a tube to the nostril or the oral cavity as in the prior art. For this reason, when measuring a respiratory state, it is not necessary to make the subject feel short of breath, a feeling of pressure, or the like. Therefore, the burden on the subject is small. Moreover, since there is little tension at the time of measurement, a normal respiratory state can be detected. Furthermore, according to the respiration sensor of the present invention, unlike the measurement of expiration and inhalation using a spirometer, the respiratory state can be detected without causing the subject to breathe consciously. For this reason, for example, the respiratory state of a patient with athetoid cerebral palsy or the like can be accurately grasped.

  Further, when the respiration sensor of the present invention is fixed to a portion that is displaced by the respiration of the subject, the respiration state can be measured regardless of the posture, state, etc. at the time of measurement. Therefore, it can be measured during exercise such as walking in addition to resting. It can also be measured while moving in a wheelchair or the like. Here, the respiration sensor of the present invention may be fixed directly to the skin of the subject, or may be indirectly fixed via clothes or the like. As described above, the respiration sensor of the present invention is useful as, for example, a medical diagnosis auxiliary instrument used at home or the like. The “subject” in the present invention includes not only humans but also animals.

  The sensor body in the present invention uses an elastomer as a base material. For this reason, the respiration sensor of the present invention is excellent in processability and has a high degree of freedom in shape. Therefore, it is easy to dispose in a non-flat part, and it can be arranged in a wide area where the part is displaced by breathing.

  In the respiration sensor of the present invention, the electrical resistance value in a no-load state can be set within a predetermined range by adjusting the type of elastomer or conductive filler, the filling rate of the conductive filler, and the like. For this reason, the range of the amount of elastic deformation that can be detected, that is, the detection range can be increased. In addition, since the increase behavior of the electrical resistance with respect to the elastic deformation amount can be adjusted, a desired response sensitivity can be realized.

  Moreover, the respiration sensor of the present invention has high conductivity in a no-load state. That is, the respiration sensor of the present invention is in a conductive state in a no-load state. For this reason, in a no-load state, operation diagnosis is easier as compared with a sensor having low conductivity (for example, a sensor using a conventional pressure-sensitive conductive resin). That is, in the case of a sensor having low conductivity in a no-load state, it is difficult to determine whether it is normal or abnormal (for example, whether a circuit is disconnected or the like) in the no-load state. For this reason, it is necessary to dare to apply a relatively high voltage to a sensor having low conductivity. Alternatively, it is necessary to check the energized state by operating the sensor on a trial basis. Therefore, the operation diagnosis is complicated. On the other hand, the respiration sensor of the present invention has high conductivity in a no-load state. For this reason, it is easy to discriminate between normal and abnormal in a no-load state. Therefore, operation diagnosis is easy. For example, the operation diagnosis can be easily performed by flowing a current through a circuit in which the respiration sensor of the present invention is incorporated at the start of measurement of the respiration state.

  (2) Preferably, in the configuration of (1) above, the configuration may be such that it is arranged in a region including at least one of the chest and abdomen of the subject (corresponding to claim 2).

  When the subject breathes, the chest and abdomen mainly expand and contract. For this reason, the amount of displacement due to respiration is large near the chest and abdomen. Therefore, according to this configuration, the amount of elastic deformation of the sensor body can be increased. As a result, the respiratory state of the subject can be detected with higher accuracy.

  (3) Preferably, in the configuration of (1) or (2), the sensor body may be configured to be elastically bendable (corresponding to claim 3). According to this configuration, the sensor body bends and deforms following the movement of the subject's body due to breathing, for example, the expansion and contraction of the chest, abdomen, and the like. For this reason, a change in electrical resistance due to bending deformation of the sensor body can be detected. When the sensor body is bent and deformed, it is easy to ensure a larger amount of elastic deformation than simple compression deformation and expansion deformation. Therefore, according to this configuration, the respiratory state of the subject can be detected with high accuracy.

  (4) Preferably, in the configuration according to any one of the above (1) to (3), the configuration further includes a base material interposed between the sensor main body and the body of the subject ( (Corresponding to claim 4).

  Here, the “subject's body” includes not only the subject's skin but also the clothes worn by the subject (the same applies to the following configurations (5) and (6)). In this configuration, the base material is made of, for example, a highly insulating material, whereby conduction from the sensor body to the subject can be blocked. Thereby, the safety | security of the respiration sensor of this invention can be improved more. Moreover, even when the respiration sensor of the present invention is directly fixed to the subject's skin by interposing a base material, the sensor body is protected from sweat, oil, etc. on the subject's skin surface. Can do. Furthermore, by adjusting the material of the base material, it is possible to prevent skin irritation of the subject, and the burden on the body of the subject can be further reduced.

  (5) Preferably, in the configuration according to any one of (1) to (4), the sensor body includes a fixed surface fixed to the body of the subject and a back surface facing away from the fixed surface. It is good to set it as the structure fixed to the said test subject's body by coat | covering with this test subject's body from the back surface side with a tape member (corresponding to claim 5).

  For example, a surgical tape or the like is known as a medical tape member. Therefore, according to this structure, the respiration sensor of this invention can be easily fixed to a subject's body using a commercially available tape member, for example. Moreover, according to this structure, the deformation | transformation of the back surface of a sensor main body is controlled by a tape member. This increases the difference between the deformation amount of the fixed surface and the deformation amount of the back surface. As a result, the amount of elastic deformation of the entire sensor body increases, and the amount of increase in electrical resistance also increases. Therefore, according to this configuration, it becomes easier to detect the respiratory state of the subject. The "fixed surface fixed to the subject's body" refers to an aspect in which the fixed surface is directly fixed to the subject's body and an aspect in which the fixed surface is indirectly fixed via a base material or the like. Includes both.

  (6) Preferably, in any one of the configurations (1) to (5), an adhesive member is disposed between the sensor main body and the body of the subject, and the subject is made by the adhesive member. It is good to set it as the structure fixed to the body (corresponding to claim 6).

  According to this configuration, the respiratory sensor of the present invention can be easily fixed to the body of the subject using an adhesive member such as a double-sided tape or an adhesive gel. Further, when combined with the configuration (5) above, the sensor body can be more firmly fixed, so that the sensor body is less likely to come off. When the base material is interposed between the sensor main body and the subject's body, the adhesive member is disposed between the base material and the subject's body. do it. That is, the adhesive member may be disposed on the contact surface of the base material with the body of the subject.

  (7) Preferably, in any one of the constitutions (1) to (6), the sensor body is made of an elastomer composition containing the elastomer and the conductive filler as essential components, In the percolation curve representing the relationship between the blending amount of the conductive filler and the electrical resistance, the blending amount (saturated volume fraction: φs) of the conductive filler at the second inflection point where the electrical resistance change is saturated is 35 vol% or more. It is good to have a configuration (corresponding to claim 7).

  Generally, when an electrically conductive filler is mixed with an insulating elastomer to form an elastomer composition, the electrical resistance of the elastomer composition varies depending on the blending amount of the conductive filler. In FIG. 3, the relationship between the compounding quantity of an electroconductive filler and an electrical resistance in an elastomer composition is shown typically.

  As shown in FIG. 3, when the conductive filler 102 is mixed with the elastomer 101, the electrical resistance of the elastomer composition is almost the same as the electrical resistance of the elastomer 101 at first. However, when the blending amount of the conductive filler 102 reaches a certain volume fraction, the electric resistance rapidly decreases and an insulator-conductor transition occurs (first inflection point). A blending amount of the conductive filler 102 at the first inflection point is referred to as a critical volume fraction (φc). Further, when the conductive filler 102 is further mixed, from a certain volume fraction, the change in electrical resistance is reduced and the change in electrical resistance is saturated (second inflection point). The blending amount of the conductive filler 102 at the second inflection point is referred to as a saturated volume fraction (φs). Such a change in electrical resistance is called a percolation curve and is considered to be due to the formation of a conductive path P1 by the conductive filler 102 in the elastomer 101.

  For example, if the conductive filler aggregates and forms an aggregate due to the small particle size of the conductive filler or poor compatibility between the conductive filler and the elastomer, one-dimensional conductive A path is easily formed. In such a case, the critical volume fraction (φc) of the elastomer composition is relatively small, such as about 20 vol%. Similarly, the saturated volume fraction (φs) is also relatively small. In other words, when the critical volume fraction (φc) and the saturated volume fraction (φs) are small, the conductive filler is unlikely to exist as primary particles, and secondary particles (aggregates) are likely to be formed. Therefore, in this case, it is difficult to blend a large amount of the conductive filler in the elastomer. That is, it is difficult to mix the conductive filler in a state close to closest packing. Further, when a large amount of a conductive filler having a small particle diameter is blended, the aggregated structure grows three-dimensionally, so that the change in conductivity with respect to elastic deformation becomes poor.

  According to this configuration, the sensor body is made of an elastomer composition having a saturated volume fraction (φs) of 35 vol% or more. Since the saturated volume fraction (φs) is as large as 35 vol% or more, the conductive filler is stably present in a substantially single particle state in the elastomer. Therefore, the conductive filler can be blended in a state close to closest packing.

  (8) Preferably, in any one of the constitutions (1) to (7), the filling rate of the conductive filler is 30 vol% or more and 65 vol% or less when the total volume of the sensor body is 100 vol%. It is good to have a configuration (corresponding to claim 8).

  According to this configuration, the conductive filler is blended in the elastomer in a state close to closest packing. Therefore, a three-dimensional conductive path by the conductive filler is easily formed in the sensor body.

  (9) Preferably, in any one of the configurations (1) to (8), the conductive filler may be a carbon bead (corresponding to claim 9).

  Carbon beads have good conductivity and are relatively inexpensive. Moreover, since it has a substantially spherical shape, it can be blended at a high filling rate.

  (10) Preferably, in any one of the configurations (1) to (9), the conductive filler may have an average particle size of 0.05 μm or more and 100 μm or less (corresponding to claim 10). .

  According to this configuration, the conductive filler hardly aggregates and is likely to exist in the form of primary particles. In addition, an average particle diameter means the average particle diameter of the electroconductive filler which exists in the state of a primary particle.

  (11) Preferably, in any one of the constitutions (1) to (10), the elastomer is silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer. It is good to set it as the structure containing 1 or more types chosen from rubber | gum and acrylic rubber (corresponding to claim 11).

  According to this configuration, the compatibility between the elastomer and the conductive filler is good. For this reason, it becomes easy for a conductive filler to exist in the state of a primary particle.

  Hereinafter, embodiments of the respiratory sensor of the present invention will be described. First, an embodiment of the respiration sensor of the present invention will be described, and then a sensor main body constituting the respiration sensor of the present invention will be described in detail.

<Respiration sensor>
First, the arrangement of the respiration sensor of this embodiment will be described. FIG. 4 shows a front view of the vicinity of the chest of the subject on which the respiration sensor of the present embodiment is arranged. In FIG. 4, the direction is defined with reference to the subject. As shown by hatching in FIG. 4, the respiration sensor 2 extends in the left-right direction near the boundary between the chest and abdomen on the left half of the subject 9. The respiration sensor 2 is connected to a control device (not shown), which will be described later, by a conducting wire (not shown).

  Next, the configuration of the respiration sensor 2 will be described. FIG. 5 shows a front view of the vicinity of the respiration sensor 2. In FIG. 5, the direction is defined with reference to the subject 9. FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. In FIG. 6, for convenience of explanation, the conductive wire is omitted. As shown in FIGS. 5 and 6, the respiration sensor 2 includes a sensor main body 20 and a base film 21.

  The base film 21 is made of polyimide and has a strip shape extending in the left-right direction. The film thickness of the base film 21 is about 0.1 mm. A connector 22 is attached to the upper left end of the base film 21. A double-sided tape 80 is disposed on the back surface (surface on the subject 9 side) of the base film 21. The base film 21 is directly fixed to the skin of the subject 9 by being attached with the double-sided tape 80. The base film 21 is included in the base material in the present invention. Moreover, the double-sided tape 80 is included in the adhesive member in the present invention.

  The sensor body 20 has a long plate shape extending in the left-right direction. The sensor body 20 has a width of about 5 mm, a length of about 100 mm, and a thickness of about 2 mm. The sensor body 20 is fixed to the surface of the base film 21. The sensor body 20 is arranged so as to be in a no-load state (natural state) in a state where the breath has been exhausted.

  The sensor body 20 is an elastomer composite material in which carbon beads (“Nika Beads (registered trademark) ICB0520” manufactured by Nippon Carbon Co., Ltd., average particle diameter of about 5 μm) are blended in EPDM (ethylene-propylene-diene terpolymer). Consists of. The filling rate of the carbon beads is 48 vol% when the volume of the sensor body 20 is 100 vol%. In the percolation curve of the elastomer composition in which carbon beads are mixed with EPDM, the critical volume fraction (φc) is 43 vol%, and the saturated volume fraction (φs) is 48 vol%.

  An electrode A is attached to the right end of the sensor body 20, and an electrode B is attached to the left end. More specifically, the electrodes A and B are each made of metal and have a strip shape extending vertically. The electrodes A and B are arranged so that a part thereof is interposed between the sensor body 20 and the base film 21. The electrode A and the connector 22 are connected by a conductive wire 23A, and the electrode B and the connector 22 are connected by a conductive wire 23B. The electrodes A and B and a control device (not shown) to be described later are connected to each other by conductive wires 23A and 23B via a connector 22.

  Next, an electrical configuration of the respiration measuring device in which the respiration sensor 2 of the present embodiment is incorporated will be described. FIG. 7 shows a block diagram of the respiratory measurement device of the present embodiment. As shown in FIG. 7, the respiration measuring device 1 of this embodiment includes a respiration sensor 2, a control device 3, and a display device 4. Here, the control device 3 includes a bridge circuit 30, an amplifier circuit 31, an input circuit 32, a waveform processing unit 33, a storage unit 34, and an output circuit 35.

  In the bridge circuit 30, resistors R1 to R3 are arranged. A Wheatstone bridge circuit is configured by the resistors R1 to R3 and the resistor R of the sensor body 20. The voltage of the power source Vin (specifically, the internal power source of the control device 3) and the electric resistance values of the resistors R1 to R3 are each known. Therefore, the resistance R of the sensor body 20 can be substantially measured by measuring the potential difference between the intermediate potential V1 between the resistor R2 and the resistor R3 and the intermediate potential V2 between the resistor R and the resistor R1. .

  Intermediate potentials V1 and V2 are input to the amplifier circuit 31. The potential difference ΔV between the intermediate potentials V1 and V2 is amplified by the amplifier circuit 31 and input to the input circuit 32 as analog voltage data. The input circuit 32 converts input analog voltage data into digital data. The digital data is input to the waveform processing unit 33. The waveform processing unit 33 removes noise and the like by performing predetermined filtering. The storage unit 34 stores the filtered digital data. The storage unit 34 is connected to the display device 4 via the output circuit 35. The display device 4 displays the digital data stored in the storage unit 34 as a voltage waveform or a resistance waveform.

  Next, the movement of the respiratory measurement device 1 of the present embodiment will be described. As described above, the sensor main body 20 is arranged so as to be in a natural state in a state where the breath is exhaled (maximum expiration state). Further, as shown in FIG. 1, in the sensor body 20 in the natural state, the conductive filler 102 is filled in a state close to the closest packing. For this reason, a large number of conductive paths P are formed. Therefore, in the maximum expiration state, the electrical resistance value of the sensor body 20 is the minimum value. When the subject inhales from this state, the chest expands, and the surface near the boundary between the chest and abdomen is displaced so that the curvature increases. Along with this, the sensor main body 20 is curved and deformed so as to be bent forward of the subject 9. Then, the electrical resistance value of the sensor body 20 (resistance R) increases. More specifically, when the sensor body 20 is bent and deformed during inhalation, the conductive fillers 102 repel each other as shown in FIG. For this reason, the conductive path P collapses. Therefore, the electric resistance value of the resistor R becomes larger with respect to the maximum expiration state. As described above, in normal times, the sensor body 20 periodically repeats the change of the natural state (maximum expiration state) → the middle bending state → the large bending state (maximum inspiration state) → the middle bending state → the natural state. Therefore, the electrical resistance value of the sensor body 20 changes according to the breathing cycle of the subject 9.

  In FIG. 8, an example of the change of the electrical resistance value obtained by the respiration measuring apparatus 1 of this embodiment is shown. As shown in FIG. 8, when the subject inhales (inhalation), the electrical resistance value of the resistance R increases. On the contrary, when the subject exhales (exhales), the electrical resistance value of the resistance R decreases. One cycle of inspiration and expiration, or one breath, is shown as one mountain waveform. Here, as shown by white double arrows in FIG. 8, when the time from expiration to expiration (the width of one mountain, that is, one cycle) is long, it is understood that the patient is in a slow breathing state. On the other hand, when the cycle is short, it is understood that the respiratory state is fast.

  Next, the effect of the respiration sensor 2 of this embodiment is demonstrated. According to the respiration sensor 2 of the present embodiment, it is not necessary to attach a device to the nostril, oral cavity, or the like as in the prior art, just by arranging it near the boundary between the chest and abdomen of the subject 9. For this reason, when measuring a respiratory state, it is not necessary to make the subject 9 feel short of breath, a feeling of pressure, or the like. The sensor body 20 is as thin as about 2 mm. For this reason, there is little sense of incongruity at the time of wearing to subject 9. Thus, according to the respiration sensor 2 of the present embodiment, the respiration state can be easily measured without imposing a burden on the subject 9. In addition, since there is little tension at the time of measurement, a normal respiratory state can be detected. In addition, the respiratory state can be detected without causing the subject 9 to consciously breathe. For this reason, according to the respiration sensor 2 of the present embodiment, for example, the respiration state of a patient with athetoid cerebral palsy can be accurately grasped.

  In addition, the amount of displacement due to respiration is large near the boundary between the chest and abdomen. For this reason, the amount of elastic deformation of the sensor body 20 accompanying respiration increases. Therefore, by disposing near the boundary between the chest and abdomen of the subject 9, the respiratory state of the subject 9 can be detected with higher accuracy. Moreover, the respiration sensor 2 of this embodiment is directly fixed to the skin of the subject 9. For this reason, it is possible to measure the respiratory state regardless of the posture and state at the time of measurement. For example, it can be measured when resting, moving with a wheelchair, etc., or exercising such as walking. Moreover, the respiration sensor 2 of this embodiment is being fixed to the skin of the subject 9 with the double-sided tape 80 stuck to the base film 21 back surface. That is, the respiration sensor 2 can be attached to the subject 9 by a simple operation of attaching with the existing double-sided tape 80.

  Further, a base film 21 made of polyimide is interposed between the sensor body 20 and the skin of the subject 9. Therefore, the conduction from the sensor body 20 to the subject 9 can be blocked. That is, the safety of the respiration sensor 2 of this embodiment is high. Further, the sensor body 20 can be protected from sweat, oil, etc. on the skin surface of the subject 9.

  The sensor body 20 uses EPDM as a base material. For this reason, the respiration sensor 2 of this embodiment is excellent in workability and has a high degree of freedom in shape. Therefore, it is easy to arrange along the body of the subject 9. Further, when the respiration measuring device 1 of the present embodiment is operated, a current flows through the respiration sensor 2 and is always energized. Thereby, an operation diagnosis can be easily performed.

  The embodiment of the respiration sensor of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

  For example, in the above embodiment, the respiration sensor is arranged near the boundary between the chest and abdomen on the left half of the subject. However, the location of the respiration sensor of the present invention is not particularly limited as long as it is a portion that is displaced by respiration. For example, the chest and abdomen are suitable. Here, the number of sensor main bodies to be arranged is not particularly limited. Two or more parts may be arranged at a portion displaced by respiration. By collecting data from a plurality of locations, detection accuracy can be improved. For example, one respiratory sensor may be arranged on each of the left and right half of the subject. By collecting data from both the left and right sides, it is possible to reduce the influence of posture changes such as turning over. Moreover, in the said embodiment, the sensor main body was arrange | positioned so that it might just be in a natural state in the maximum expiration state. However, the reference state of the sensor body may be appropriately determined in consideration of the ease of analysis of the obtained data. For example, you may arrange | position so that it may just be in a natural state in the maximum inhalation state.

  The configuration of the sensor body is not limited to the above embodiment. This will be described later. Further, the size and shape of the sensor body are not particularly limited. From the viewpoint of reducing the burden on the subject, the sensor body may be sized so as not to give the subject a sense of incongruity. For example, it is preferable that the thickness of the sensor body is 3 mm or less, further 1 mm or less. The shape of the sensor main body may be a square plate shape, a disc shape, or the like in addition to the long plate shape of the above embodiment.

  Further, the number of electrodes connected to the sensor body is not particularly limited. For example, in the case of a long sensor body as in the present embodiment, if electrodes are arranged at predetermined intervals in the longitudinal direction, the respiratory state can be detected at intervals between adjacent electrodes. By collecting data from a plurality of locations, for example, even if there is a section where it is difficult to detect the respiratory state due to posture or the like, the respiratory state can be detected from data in other sections. When the electrode is fixed to the sensor body by vulcanization adhesion, the electrode can be disposed simultaneously with the vulcanization molding of the sensor body.

  In the said embodiment, the respiration sensor was directly fixed to the subject's skin. However, the respiratory sensor of the present invention may be indirectly fixed from above the subject's clothes. Moreover, in the said embodiment, the base material was interposed between the sensor main body and the subject's skin. However, you may arrange | position to a subject's body, without interposing a base material. When interposing a base material, the material of the base material is not particularly limited. What is necessary is just to determine suitably in consideration of insulation, the burden on a subject's skin, etc. Further, from the viewpoint of reducing the burden on the subject, it is preferable that the thickness of the base material is 0.4 mm or less, further 0.2 mm or less.

  Moreover, the fixing method of the respiration sensor with respect to a subject's body is not limited to the said embodiment. For example, the respiratory sensor may be fixed using a tape member such as a surgical tape. In this case, the respiration sensor may be fixed to the body of the subject by covering the tape member from the back side opposite to the fixing surface of the sensor body. Moreover, it may replace with the double-sided tape (adhesive member) of the said embodiment, and may just coat | cover a tape member from the back surface side of a sensor main body.

  The configurations of the control device and the display device connected to the respiration sensor of the present invention are not particularly limited. For example, the control device may include a calculation unit that can determine whether the respiratory state is normal or abnormal. In this case, when it is determined that the respiratory state is abnormal, an alarm can be sounded by an alarm device or the like to alert the subject or the measurer. For example, digital data is input from the input circuit to the calculation unit, and the calculation unit calculates the respiratory amplitude from the potential difference ΔV (ΔV after digital conversion) accumulated for a predetermined time. On the other hand, the storage unit stores an amplitude lower limit threshold and an amplitude upper threshold. The computing unit compares the calculated respiratory amplitude with these amplitude lower limit threshold and amplitude upper threshold. In normal times, amplitude lower limit threshold <respiration amplitude <amplitude upper threshold. For example, at the time of an abnormality that makes breathing weak, the amount of bending of the sensor body in one breathing cycle is small. For this reason, a respiratory amplitude becomes small. Therefore, as a result of calculation in the calculation unit, respiratory amplitude ≦ amplitude lower limit threshold. In this case, an alarm is promptly output from the alarm device. Thus, you may implement in the form which outputs a warning according to the calculation result of a calculating part.

  Further, the display device may not always be connected to the control device. You may connect to the controller only when you want to know your breathing status. The type of the display device is not particularly limited, and examples thereof include a screen of a personal computer, a data output sheet, and the like.

<Sensor body>
The sensor body constituting the respiration sensor of the present invention has an elastomer and a conductive filler. The elastomer can be appropriately selected from rubber and thermoplastic elastomer. The elastomer is desirably insulative. In addition, when a mixture (elastomer composition) with a conductive filler is prepared, it is desirable to use one having a saturated volume fraction (φs) in a percolation curve of 35 vol% or more. This is because when the saturated volume fraction (φs) is less than 35 vol%, it is difficult to blend the conductive filler in a substantially single particle state with a high filling rate. Further, in the region of the saturated volume fraction (φs) or more, the electric resistance is low and stable conductivity is expressed. Therefore, when the saturated volume fraction (φs) is 35 vol% or more, the range of change in electrical resistance from the conductor to the insulator when elastically deformed is widened. Further, it is more preferable to use a saturated volume fraction (φs) of 40 vol% or more. In addition, the “elastomer composition” in the present specification includes an elastomer and a spherical conductive filler as essential components. That is, a mixture of an elastomer and a spherical conductive filler may be used, or a mixture of an elastomer, a spherical conductive filler, and other additives may be used.

In consideration of the affinity with the conductive filler, an elastomer having a gel fraction represented by the following formula (1) of 15% or less may be used. The gel fraction is more preferably 10% or less.
Gel fraction (%) = (Wg−Wf) / Wf × 100 (1)
[Wg in the formula (1) is a solvent-insoluble content (gel content comprising a conductive filler and an elastomer) obtained when an elastomer composition obtained by mixing a conductive filler in an elastomer is dissolved in a good solvent for the elastomer. It is weight. Wf is the weight of the conductive filler. In addition, as a good solvent of an elastomer, the thing with the close SP value (solubility parameter) of a solvent and an elastomer is desirable, For example, toluene, tetrahydrofuran, chloroform, etc. are mentioned. ]

  The value of the gel fraction is an indicator of the critical volume fraction (φc) in the percolation curve. That is, when the critical volume fraction (φc) is less than 30 vol%, the gel fraction becomes a relatively large value because a large amount of elastomer adsorbed and bonded to the aggregate of the conductive filler exists. On the other hand, when the critical volume fraction (φc) is 30 vol% or more, the conductive filler exists in a substantially single particle state, so that the amount of elastomer adsorbed and bonded to the aggregate of the conductive filler is small, and the gel The fraction is a relatively small value of 15% or less.

  Specific examples of elastomers include, for example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), styrene-butadiene copolymer rubber (SBR), Ethylene-propylene copolymer rubber [ethylene-propylene copolymer (EPM), ethylene-propylene-diene terpolymer (EPDM), etc.], butyl rubber (IIR), halogenated butyl rubber (Cl-IIR, Br-IIR, etc.) ), Hydrogenated nitrile rubber (H-NBR), chloroprene rubber (CR), acrylic rubber (AR), chlorosulfonated polyethylene rubber (CSM), hydrin rubber, silicone rubber, fluorine rubber, urethane rubber, synthetic latex and the like. . Examples of the thermoplastic elastomer include various thermoplastic elastomers such as styrene, olefin, urethane, polyester, polyamide, and fluorine, and derivatives thereof. Of these, one kind may be used alone, or two or more kinds may be used in combination. Of these, EPDM having extremely good compatibility with the conductive filler is preferable. Also suitable are NBR and silicone rubber, which have good compatibility with the conductive filler.

  The conductive filler has a spherical shape. The spherical shape includes not only a true sphere and a substantially true sphere, but also an oval sphere, an oval sphere (a shape in which a pair of opposing hemispheres are connected by a cylinder), a partial sphere, a sphere having a different radius for each portion, a water droplet shape, and the like. included. For example, the aspect ratio of the conductive filler (the ratio of the long side to the short side) is preferably in the range of 1 or more and 2 or less. This is because when the aspect ratio is larger than 2, a one-dimensional conductive path is easily formed by contact between the conductive fillers. In this case, the saturated volume fraction (φs) may be less than 35 vol%. Further, from the viewpoint of bringing the filling state of the conductive filler in the elastomer closer to the closest packing state, it is preferable to employ particles having a true sphere or a shape very close to a true sphere (substantially spherical) as the conductive filler.

  The conductive filler is not particularly limited as long as it is conductive particles. Examples thereof include fine particles such as carbon materials and metals. Of these, one can be used alone, or two or more can be used in combination.

  It is desirable that the conductive filler is not aggregated as much as possible and exists in the form of primary particles. Therefore, when selecting the conductive filler, it is preferable to consider the average particle diameter, compatibility with the elastomer, and the like. For example, the average particle diameter (primary particles) of the conductive filler is desirably 0.05 μm or more and 100 μm or less. If it is less than 0.05 μm, it tends to aggregate and form secondary particles. Moreover, there exists a possibility that the said saturated volume fraction ((phi) s) may be less than 35 vol%. Preferably it is 0.5 micrometer or more, More preferably, it is 1 micrometer or more. On the other hand, when the thickness exceeds 100 μm, the translational motion (parallel motion) of the conductive filler due to elastic deformation becomes relatively smaller than the particle diameter, and the change in electric resistance against the elastic deformation of the sensor body becomes slow. Preferably it is 60 micrometers or less, More preferably, it is 30 micrometers or less. In addition, the critical volume fraction (φc) and the saturated volume fraction (φs) are within the desired ranges by appropriately adjusting the combination of the conductive filler and the elastomer, the average particle diameter of the conductive filler, and the like. Can be adjusted.

  Moreover, as for the value of D90 / D10 in the particle size distribution of an electroconductive filler, it is desirable that it is 1-30. Here, D90 is the particle diameter at which the cumulative weight is 90% in the cumulative particle size curve, and D10 is the particle diameter at which the cumulative weight is 10%. When the value of D90 / D10 exceeds 30, since the particle size distribution becomes broad, the increase behavior of the electric resistance with respect to the deformation amount of the sensor body becomes unstable. Thereby, the reproducibility of detection may be reduced. It is more preferable that the value of D90 / D10 is 10 or less. In addition, when using 2 or more types of particle | grains as an electroconductive filler, the value of D90 / D10 should just be 100 or less.

  As such a conductive filler, for example, carbon beads are suitable. Specifically, Osaka Gas Chemical Co., Ltd. mesocarbon micro beads [MCMB6-28 (average particle size of about 6 μm), MCMB10-28 (average particle size of about 10 μm), MCMB25-28 (average particle size of about 25 μm)], Carbon micro beads manufactured by Nippon Carbon Co., Ltd .: Nika beads (registered trademark) ICB, Nika beads PC, Nika beads MC, Nika beads MSB [ICB 0320 (average particle size of about 3 μm), ICB 0520 (average particle size of about 5 μm), ICB 1020 (average particle size of about 10 μm) ), PC0720 (average particle diameter of about 7 μm), MC0520 (average particle diameter of about 5 μm)], Nisshinbo carbon beads (average particle diameter of about 10 μm), and the like.

  The conductive filler is blended in the elastomer at a high filling rate. In order to develop desired conductivity, the conductive filler is desirably blended at a ratio equal to or higher than the critical volume fraction (φc) in the percolation curve. From the viewpoint of blending the conductive filler in a substantially single particle state with a high filling rate, the critical volume fraction (φc) is desirably 30 vol% or more. It is more preferable that it is 35 vol% or more. Therefore, for example, the filling rate of the conductive filler is desirably 30 vol% or more and 65 vol% or less when the entire volume of the sensor body is 100 vol%. In the case of less than 30 vol%, the conductive filler is not blended in a state close to the closest packing, and thus desired conductivity is not exhibited. In addition, the change in the electric resistance with respect to the elastic deformation of the sensor body becomes slow, and it becomes difficult to control the increase behavior of the electric resistance. It is more preferable that it is 35 vol% or more. On the other hand, when it exceeds 65 vol%, mixing with the elastomer becomes difficult, and the molding processability is lowered. In addition, the sensor body is less likely to be elastically deformed. It is more preferable that it is 55 vol% or less.

  In addition to the elastomer and the conductive filler, various additives may be blended in the sensor body. Examples of the additive include a crosslinking agent, a vulcanization accelerator, a vulcanization aid, an antiaging agent, a plasticizer, a softening agent, and a colorant. In addition to the spherical conductive filler, a conductive filler having an irregular shape (for example, a needle shape) may be blended.

  The sensor body can be manufactured, for example, as follows. First, additives such as a vulcanization aid and a softening agent are added to the elastomer and kneaded. Subsequently, after adding a conductive filler and kneading, a crosslinking agent and a vulcanization accelerator are further added and kneaded to obtain an elastomer composition. Next, the elastomer composition is formed into a sheet, filled in a mold, and press vulcanized under predetermined conditions.

  Hereinafter, a respiration measurement test using the respiration sensor of the present invention will be described.

<Test method>
A respiration measurement test was performed using the respiration sensor 2 of the above embodiment (see FIG. 5 above). Here, the sensor main body was produced as follows. First, 85 parts by weight (85 g) of oil-extended EPDM (“Esprene (registered trademark) 6101” manufactured by Sumitomo Chemical Co., Ltd.) (34 g) and 34 (Oil-extended EPDM (“Esplen 601” manufactured by Sumitomo Chemical Co., Ltd.)) 34 Part (34 g), 30 parts (30 g) of EPDM (“Esplen 505” manufactured by Sumitomo Chemical Co., Ltd.), 5 parts (5 g) of zinc oxide (manufactured by Hakusui Chemical Co., Ltd.), and stearic acid (“Lunac” (registered by Kao Corporation) 1 part (1 g) of trademark S30 ") and 20 parts (20 g) of paraffinic process oil (" Samper (registered trademark) 110 "manufactured by Nippon San Oil Co., Ltd.) were kneaded with a roll kneader. Next, 270 parts (270 g) of carbon beads (“Nika Beads ICB0520” manufactured by Nippon Carbon Co., Ltd., average particle diameter of about 5 μm, D90 / D10 = 3.2 in the particle size distribution) are added and mixed in a roll kneader, Dispersed. Furthermore, as a vulcanization accelerator, zinc dimethyldithiocarbamate (“Noxeller (registered trademark) PZ-P” manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts (1.5 g), tetramethylthiuram disulfide (manufactured by Sanshin Chemical Co., Ltd.) "Sunseller (registered trademark) TT-G") 1.5 parts (1.5 g), 2-mercaptobenzothiazole ("Noxeller MP" manufactured by Ouchi Shinsei Chemical) 0.5 parts (0.5 g) And 0.56 part (0.56 g) of sulfur (“Sulfax T-10” manufactured by Tsurumi Chemical Co., Ltd.) were added, mixed and dispersed with a roll kneader to prepare an elastomer composition.

  The volume fraction of carbon beads in the prepared elastomer composition was about 48 vol% when the volume of the entire elastomer composition was 100 vol%. Further, the critical volume fraction (φc) in the percolation curve of the elastomer composition was about 43 vol%, and the saturated volume fraction (φ s) was about 48 vol%. Moreover, when the elastomer composition was dissolved in a solvent (toluene) and the solvent insoluble content was measured, the gel fraction was about 3%.

  Next, the elastomer composition was molded into a band having a predetermined size to obtain a molded body. The molded body was filled in a mold, electrodes were arranged at both ends in the longitudinal direction, and press vulcanized at 170 ° C. for 30 minutes to obtain a sensor main body equipped with the electrodes. The filling rate of carbon beads in the obtained sensor main body was about 48 vol% when the volume of the sensor main body was 100 vol%.

  The produced sensor body and electrodes were fixed on a polyimide base film to constitute a respiration sensor. As shown in FIG. 5, the respiration sensor was disposed near the boundary between the chest and abdomen on the left half of the subject. On the other hand, a temperature sensor was disposed under the nostril of the subject.

  Three types of respiration measurement tests were conducted as follows. In the first test, the subject took normal breathing, and the change in the electrical resistance value of the breathing sensor during normal time was measured. In the second test, the subject consciously took a large abdominal breath to measure the change in electrical resistance of the breathing sensor during abdominal breathing. In the third test, the subject was intentionally breathing with the chest type consciously, and the change in the electrical resistance value of the respiratory sensor during the chest type breathing was measured. In any of the first to third tests, the temperature under the nostril of the subject was measured with a temperature sensor.

<Test results>
The results of each respiration measurement test are shown in FIGS. FIG. 9 shows the electrical resistance value of the respiration sensor (resistance R, hereinafter the same in FIG. 10 and FIG. 11) and the temporal change in the temperature of the nostril during normal respiration. FIG. 10 shows changes over time in the electrical resistance value of the respiratory sensor and the temperature under the nostril during abdominal breathing. FIG. 11 shows changes over time in the electrical resistance value of the breathing sensor and the temperature under the nostril during chest breathing.

  As shown in FIGS. 9 to 11, the change in the electrical resistance value corresponds to the change in the subnasal temperature regardless of the type of breathing. From this, it can be seen that according to the respiration sensor of the present invention, the respiration cycle can be measured regardless of the type of respiration. Further, since the waveform corresponding to the type of respiration is obtained, it can be seen that the respiration sensor of the present invention can accurately grasp the respiration cycle and respiration depth, that is, the respiration state.

  For example, when breathing greatly by the chest type or the abdominal type, the respiratory state can be grasped to some extent from the electrocardiogram waveform obtained by the electrocardiograph and the electromyogram waveform obtained by the electromyograph. However, in the case of normal breathing, it is difficult to grasp the breathing state because a peak indicating breathing does not appear easily in the electrocardiogram waveform and the electromyogram waveform. In this regard, according to the respiration sensor of the present invention, the respiration state can be accurately measured even during normal respiration. In addition, the respiratory cycle can be easily obtained by Fourier transforming the obtained electrical resistance value data to obtain the regularity cycle.

It is a schematic diagram which shows the electroconductive path before the load application of the sensor main body in this invention. It is a schematic diagram which shows the conductive path after the load application of the sensor main body. It is a schematic diagram of the percolation curve in an elastomer composition. It is a front view near the chest of the subject where the respiration sensor of the embodiment of the present invention is arranged. It is a front view of the vicinity of the respiration sensor. It is VI-VI sectional drawing of FIG. It is a block diagram of the respiration measuring apparatus incorporating the respiration sensor. It is a graph which shows an example of the change of the electrical resistance value obtained by the respiration measuring device. It is a graph which shows the electrical resistance value of the respiration sensor in a respiration measurement test, and a temporal change of nostril temperature (normal time). It is a graph which shows the electrical resistance value of the respiration sensor in a respiration measurement test, and a time-dependent change of the temperature under a nostril (at the time of abdominal respiration). It is a graph which shows the electrical resistance value of the respiration sensor in a respiration measurement test, and a time-dependent change of the temperature under a nostril (at the time of chest respiration).

Explanation of symbols

1: Respiration measurement device 2: Respiration sensor 20: Sensor body 21: Base film (base material) 22: Connector 23A, 23B: Conductor 3: Controller 30: Bridge circuit 31: Amplifier circuit 32: Input circuit 33: Waveform processing Unit 34: Storage unit 35: Output circuit 4: Display device 80: Double-sided tape (adhesive member) 9: Subject 100: Sensor body 101: Elastomer 102: Conductive filler A, B: Electrode ΔV: Potential difference R: Resistance R1 ~ R3: Resistors V1, V2: Intermediate potential Vin: Power supply P: Conductive path P1: Conductive path

Claims (11)

An elastically deformable sensor main body having an elastomer and a spherical conductive filler blended in the elastomer in a substantially single particle state and with a high filling rate, and increasing in electric resistance as the amount of elastic deformation increases When,
An electrode connected to the sensor body and capable of outputting the electrical resistance;
With
The sensor body is elastically deformed with the movement of the body of the subject due to respiration, and a respiration sensor capable of detecting the breathing state of the subject from the change over time of the electrical resistance based on the elastic deformation of the sensor body .   The respiratory sensor according to claim 1, wherein the respiratory sensor is disposed in a region including at least one of the chest and abdomen of the subject.   The respiration sensor according to claim 1, wherein the sensor body is elastically bendable.   Furthermore, the respiration sensor in any one of Claim 1 thru | or 3 which has a base material interposed between the said sensor main body and the said test subject's body. The sensor body has a fixed surface fixed to the body of the subject, and a back surface facing away from the fixed surface,
The respiration sensor according to any one of claims 1 to 4, wherein the respiration sensor is fixed to the body of the subject by covering with the body of the subject from the back surface side with a tape member. An adhesive member is disposed between the sensor body and the subject's body,
The respiration sensor according to any one of claims 1 to 5, wherein the respiration sensor is fixed to the body of the subject by the adhesive member. The sensor body is composed of an elastomer composition containing the elastomer and the conductive filler as essential components,
In the percolation curve representing the relationship between the blending amount of the conductive filler and the electrical resistance of the elastomer composition, the blending amount of the conductive filler at the second inflection point at which the electrical resistance change is saturated (saturated volume fraction: φs) ) Is 35 vol% or more. The respiratory sensor according to any one of claims 1 to 6.   The respiration sensor according to any one of claims 1 to 7, wherein a filling rate of the conductive filler is 30 vol% or more and 65 vol% or less when the entire volume of the sensor main body is 100 vol%.   The respiratory sensor according to any one of claims 1 to 8, wherein the conductive filler is carbon beads.   The respiratory sensor according to any one of claims 1 to 9, wherein an average particle diameter of the conductive filler is 0.05 µm or more and 100 µm or less.   11. The elastomer according to claim 1, wherein the elastomer includes one or more selected from silicone rubber, ethylene-propylene copolymer rubber, natural rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, and acrylic rubber. Respiration sensor according to.

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