JP2019136230A - Swallowing detection sensor and swallowing detection system - Google Patents

Abstract

To provide a swallowing detection sensor capable of accurately measuring as much information as possible by a simple measurement which does not adversely affect a human body, and to provide a swallowing detection system using the sensor.SOLUTION: There is provided a swallowing detection sensor in which the neck part includes a braid formed of a conductive fiber and a piezoelectric fiber, the conductive fiber being the core of the braid. The swallowing detection sensor is a piezoelectric structure in which the piezoelectric fiber is a coating fiber that coats the circumference of the conductive fiber. The coating fiber includes at least one bent part, and when the piezoelectric structure is placed on a horizontal plane, the height from the horizontal plane to the uppermost part of the piezoelectric structure is greater than the diameter of the coating fiber. There is also provided a swallowing detection system using the swallowing detection sensor.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a swallowing detection sensor including a piezoelectric element using a braided piezoelectric element using a piezoelectric fiber, and a swallowing detection system using the same.

  Aspiration pneumonia accounts for a high proportion of causes of death, and if the swallowing function declines, it becomes easier to cause aspiration during meals, so the medical institution or care facility grasps the swallowing function of the subject It is important to. As a swallowing function inspection method for obtaining detailed information, swallowing contrast inspection and swallowing endoscopy are generally performed. A swallowing contrast test is a test that ingests food containing a contrast medium and confirms that it passes through the esophagus with X-rays, but it requires expensive equipment and specialized personnel. There is a problem in that allergies to contrast media and aspiration due to the test itself are concerned. In swallowing endoscopy, a device such as a thin camera is inserted from the nose to observe the throat. However, when swallowing movements cannot be observed, and when the pharyngeal reflex is strong, nausea can be used to perform a sufficient examination. There are problems in that there are concerns about local anesthetic allergies and nasal bleeding due to endoscopic insertion.

  On the other hand, repeated saliva swallowing test, revised water swallowing test and food test are performed as simple swallowing function testing methods, but there are problems in that the test accuracy and objectivity, especially sensitivity to mild dysphagia is low. is there.

  Patent Document 1 discloses a swallowing ability inspection device in which an air bag is arranged in a region around a larynx of a living body and air pressure in the air bag is transmitted by an air tube. However, there are problems in that the structure and piping are complicated and thought to require labor, and the position of the air bag needs to be adjusted according to the difference in the shape and size of the subject's throat. is there.

  Patent Document 2 includes an optical fiber and a sheet-like body that supports the optical fiber, and includes an optical fiber sheet that is attached to the larynx of a subject, and relates to the outer shape variation of the larynx associated with swallowing movement. A swallowing movement monitoring sensor that detects a change in the amount of transmitted light based on a loss caused by a lateral pressure applied to an optical fiber from the larynx is disclosed. However, optical fibers are generally inflexible, and it is questionable whether they can sufficiently follow the movement of the subject's larynx during swallowing. Also, depending on the shape and size of the subject's larynx, There is a problem in that it is necessary to adjust the fiber sheet.

  In Patent Document 3, as a combination of conductive fibers and piezoelectric fibers, a braided piezoelectric element in which the surface of a conductive fiber serving as a core is covered with braided piezoelectric fibers inhibits the movement and state of an object. It is disclosed as a sensor that does not. However, as a use for humans, it has been described for use in collecting information on joint movement, but it is not a joint movement, and it is used for a swallowing function test that requires a short observation of around 0.5 seconds. Whether it can be used is not described.

Japanese Patent Laid-Open No. 2015-100382 JP 2017-38840 A JP 2017-120861 A

  The present invention has been made in view of the above-described background, and an object of the present invention is to provide a swallowing detection sensor and its sensor capable of measuring as much information as possible with high accuracy and without adversely affecting the human body. It is to provide a swallowing detection system used.

  As a combination of a conductive fiber and a piezoelectric fiber, the inventors of the present invention have a sensor including a braided piezoelectric element in which the surface of a conductive fiber serving as a core is covered with a braided piezoelectric fiber. It was discovered that it can be used as a sensor for swallowing detection that does not impede, and the present invention has been achieved.

That is, the present invention includes the following inventions.
1. A swallowing detection sensor comprising a fibrous structure that can be attached to a neck.
2. 2. The swallowing detection sensor according to 1 above, comprising a string-like piezoelectric element.
3. 3. The swallowing detection sensor according to 2 above, wherein the piezoelectric element is a braided piezoelectric element.
4). The braided piezoelectric element includes a core portion formed of conductive fiber and a sheath portion formed of braided piezoelectric fiber so as to cover the core portion, and the piezoelectric fiber is a main component 4. The swallowing detection sensor according to 3, wherein the wrapping angle of the piezoelectric fiber with respect to the conductive fiber is 15 ° or more and 75 ° or less.
5). 4. The swallowing detection sensor according to 3 above, wherein the total fineness of the piezoelectric fiber is ½ to 20 times the total fineness of the conductive fiber.
6). 4. The swallowing detection sensor according to 3 above, wherein the fineness per piezoelectric fiber is 1/20 or more and 2 or less of the total fineness of the conductive fiber.
7). The swallowing detection sensor according to any one of the above items 2 to 6, wherein two or more string-like piezoelectric elements are used.
8). 8. The swallowing detection sensor according to any one of 2 to 7, wherein the string-like piezoelectric element is arranged in a horizontal direction when in use.
9. 9. The swallowing detection sensor according to any one of 2 to 8, wherein the string-like piezoelectric element is fixed to a fiber structure.
10. 10. The swallowing detection sensor according to 9, wherein the string-like piezoelectric element is fixed to a fiber structure with an adhesive substance.
11. 10. The swallowing detection sensor according to 9 above, wherein the string-like piezoelectric element is fixed to the fiber structure by sewing.
12 10. The swallowing detection sensor according to 9 above, wherein the string-like piezoelectric element is part of a fiber structure.
13. A swallowing detection system using the swallowing detection sensor.
14 14. The swallowing detection system according to 13 above, wherein the swallowing detection sensor is used to detect a temporal change in the position of the pharyngeal elevation.

  According to the present invention, it is possible to provide a swallowing detection sensor using a piezoelectric element and a swallowing detection system using the same, which are simple to wear and measure and can obtain more information at a high response speed.

It is a figure which shows typically the generation principle of the electrical signal in the combination of an electroconductive fiber and a piezoelectric fiber. It is a figure which shows an example of the swallowing detection sensor of this invention. It is a figure which shows typically a mode that the swallowing detection sensor of this invention was worn on the neck part. It is an example of the block diagram which can be employ | adopted with the swallowing detection system of this invention. 3 is a measurement profile obtained in Example 1. 3 is a measurement profile obtained in Example 2.

(Braided piezoelectric element)
FIG. 1 is a schematic diagram illustrating a configuration example of a braided piezoelectric element according to the embodiment.
The braided piezoelectric element 1 includes a core portion 3 formed of a conductive fiber B and a sheath portion 2 formed of a braided piezoelectric fiber A so as to cover the core portion 3. The piezoelectric fiber A can contain polylactic acid as a main component. The winding angle α of the piezoelectric fiber A with respect to the conductive fiber B is 15 ° or more and 75 ° or less.

  In the braided piezoelectric element 1, a large number of piezoelectric fibers A densely surround the outer peripheral surface of at least one conductive fiber B. Although not bound by a specific theory, when the braided piezoelectric element 1 is deformed, a stress due to the deformation is generated in each of the many piezoelectric fibers A, thereby generating an electric field in each of the many piezoelectric fibers A. (Piezoelectric effect) As a result, it is presumed that a voltage change in which electric fields of a large number of piezoelectric fibers A surrounding the conductive fiber B are superimposed is generated in the conductive fiber B. That is, the electrical signal from the conductive fiber B increases as compared with the case where the braided sheath 2 of the piezoelectric fiber A is not used. As a result, the braided piezoelectric element 1 can extract a large electric signal even by a stress generated by a relatively small deformation. A plurality of conductive fibers B may be used.

  Here, the piezoelectric fiber A preferably contains polylactic acid as a main component. “As a main component” means that the most component of the components of the piezoelectric fiber A is polylactic acid. The lactic acid unit in the polylactic acid is preferably 90 mol% or more, more preferably 95 mol% or more, and even more preferably 98 mol% or more.

  Further, the winding angle α of the piezoelectric fiber A with respect to the conductive fiber B is 15 ° or more and 75 ° or less. That is, the winding angle α of the piezoelectric fiber A is 15 ° or more and 75 ° or less with respect to the direction of the central axis CL of the conductive fiber B (core portion 3). However, in the present embodiment, the central axis CL of the conductive fiber B overlaps with the central axis (hereinafter, also referred to as “braid axis”) of the braided cord (sheath portion 2) of the piezoelectric fiber A. It can also be said that the winding angle α of the piezoelectric fiber A is 15 ° or more and 75 ° or less with respect to the direction of the braid axis of A. From the viewpoint of extracting a larger electric signal, the angle α is preferably 25 ° or more and 65 ° or less, more preferably 35 ° or more and 55 ° or less, and 40 ° or more and 50 ° or less. Is more preferable. This is because when the angle α is out of this angle range, the electric field generated in the piezoelectric fiber A is remarkably lowered, and the electrical signal obtained from the conductive fiber B is thereby remarkably lowered.

  The angle α can also be referred to as an angle formed by the main direction of the piezoelectric fiber A forming the sheath portion 2 and the central axis CL of the conductive fiber B, and a part of the piezoelectric fiber A is slackened. Or may be fuzzy.

Here, the reason why the electric field generated in the piezoelectric fiber A is remarkably lowered is as follows. The piezoelectric fiber A has polylactic acid as a main component and is uniaxially oriented in the fiber axis direction of the piezoelectric fiber A. Here, polylactic acid generates an electric field when shear stress is generated in the orientation direction (in this case, the direction of the fiber axis of the piezoelectric fiber A), but tensile stress or compression is applied in the orientation direction. Less electric field is generated when stress occurs. Therefore, in order to generate shear stress in the piezoelectric fiber A when deformed parallel to the direction of the braid axis, the orientation direction of the piezoelectric fiber A (polylactic acid) is within a predetermined angular range with respect to the braid axis. It is speculated that it is good to be.

  In the braided piezoelectric element 1, as long as the object of the present invention is achieved, the sheath 2 may be mixed with fibers other than the piezoelectric fiber A, and the core 3 may be conductive. Mixing or the like may be performed in combination with fibers other than the fiber B.

  The length of the braided piezoelectric element composed of the core portion 3 of the conductive fiber B and the sheath portion 2 of the braided piezoelectric fiber A is not particularly limited. For example, the braided piezoelectric element may be manufactured continuously in manufacturing, and then cut to a required length for use. The length of the braided piezoelectric element is 1 mm to 50 cm, preferably 5 mm to 45 cm, more preferably 1 cm to 45 cm. If the length is too short, the convenience of the fiber shape is lost, and a length longer than the neck length is unnecessary.

(Fixed braided piezoelectric element)
As a method for fixing the braided piezoelectric element, any method can be adopted according to the object and its purpose. For example, a method of sticking using an adhesive such as glue or adhesive, a method of fixing with a magnet, heat, a clip, or the like, or a method of sewing or bending a cloth-like object like embroidery Also, a method of fixing the braided object by twisting it so that the braided piezoelectric element is located on the surface or inside, packing the braided string on the object and packing the object and braid together However, this is not a limitation. Further, the braided piezoelectric element does not need to be fixed so as to be a straight line, and can be arbitrarily fixed, such as a curve, according to the object and purpose.

Hereinafter, each configuration will be described in detail.
(Conductive fiber)
As the conductive fiber B, any known fiber may be used as long as it exhibits conductivity. As the conductive fiber B, for example, metal fiber, fiber made of a conductive polymer, carbon fiber, fiber made of a polymer in which a fibrous or granular conductive filler is dispersed, or conductive on the surface of a fibrous material. The fiber which provided the layer which has is mentioned. Examples of a method for providing a conductive layer on the surface of the fiber structure include a metal coat, a conductive polymer coat, and winding of conductive fibers. Among these, a metal coat is preferable from the viewpoint of conductivity, durability, flexibility and the like. Specific methods for coating the metal include vapor deposition, sputtering, electrolytic plating, and electroless plating, but plating is preferable from the viewpoint of productivity. Such a metal-plated fiber can be referred to as a metal-plated fiber.

  As a base fiber for coating a metal, a known fiber can be used regardless of conductivity. For example, polyester fiber, nylon fiber, acrylic fiber, polyethylene fiber, polypropylene fiber, vinyl chloride fiber, aramid fiber, polysulfone In addition to synthetic fibers such as fibers, polyether fibers and polyurethane fibers, natural fibers such as cotton, hemp and silk, semi-synthetic fibers such as acetate, and regenerated fibers such as rayon and cupra can be used. The base fibers are not limited to these, and known fibers can be arbitrarily used, and these fibers may be used in combination.

  Any metal may be used as long as the metal coated on the base fiber exhibits conductivity and exhibits the effects of the present invention. For example, gold, silver, platinum, copper, nickel, tin, zinc, palladium, indium tin oxide, copper sulfide, and a mixture or alloy thereof can be used.

  When an organic fiber coated with metal having bending resistance is used for the conductive fiber B, the conductive fiber is hardly broken and excellent in durability and safety as a sensor using a piezoelectric element. The conductive fiber B may be a multifilament in which a plurality of filaments are bundled, or may be a monofilament composed of a single filament. A multifilament is preferred from the viewpoint of long stability of electrical characteristics. In the case of monofilament (including spun yarn), the single yarn diameter is 1 μm to 5000 μm, preferably 2 μm to 100 μm. More preferably, it is 3 micrometers-50 micrometers. In the case of a multifilament, the number of filaments is preferably 1 to 100,000, more preferably 5 to 500, and still more preferably 10 to 100. However, the fineness and the number of the conductive fibers B are the fineness and the number of the core part 3 used when producing the braid, and the multifilament formed of a plurality of single yarns (monofilaments) is also one conductive. It shall be counted as fiber B. Here, the core portion 3 is the total amount including the fibers other than the conductive fibers.

  If the diameter of the fiber is small, the strength is reduced and handling becomes difficult, and if the diameter is large, flexibility is sacrificed. The cross-sectional shape of the conductive fiber B is preferably a circle or an ellipse from the viewpoint of the design and manufacture of the piezoelectric element, but is not limited thereto.

Moreover, in order to efficiently extract the electrical output from the piezoelectric polymer, the electrical resistance is preferably low, and the volume resistivity is preferably 10 ⁻¹ Ω · cm or less, more preferably 10 ⁻² Ω · cm. cm or less, more preferably 10 ⁻³ Ω · cm or less. However, the resistivity of the conductive fiber B is not limited to this as long as sufficient strength can be obtained by detection of the electric signal.

The conductive fiber B must be resistant to movement such as repeated bending and twisting from the use of the present invention. As the index, one having a greater nodule strength is preferred. The nodule strength can be measured by the method of JIS L1013 8.6. The degree of knot strength suitable for the present invention is preferably 0.5 cN / dtex or more, more preferably 1.0 cN / dtex or more, and further preferably 1.5 cN / dtex or more. 2.0 cN / dtex or more is most preferable. As another index, one having a smaller bending rigidity is preferred. The bending rigidity is generally measured by a measuring device such as KES-FB2 pure bending tester manufactured by Kato Tech Co., Ltd. The degree of bending rigidity suitable for the present invention is preferably smaller than the carbon fiber “Tenax” (registered trademark) HTS40-3K manufactured by Toho Tenax Co., Ltd. Specifically, the bending stiffness of the conductive fiber is preferably 0.05 × 10 ⁻⁴ N · m ² / m or less, and preferably 0.02 × 10 ⁻⁴ N · m ² / m or less. More preferably, it is more preferably 0.01 × 10 ⁻⁴ N · m ² / m or less.

(Piezoelectric fiber)
As the piezoelectric polymer that is the material of the piezoelectric fiber A, a polymer exhibiting piezoelectricity such as polyvinylidene fluoride or polylactic acid can be used. However, in the present embodiment, the piezoelectric fiber A is used as a main component as described above. It is preferred to include polylactic acid. Polylactic acid, for example, is easily oriented by drawing after melt spinning and exhibits piezoelectricity, and is excellent in productivity in that it does not require an electric field alignment treatment required for polyvinylidene fluoride and the like. However, this is not intended to exclude the use of polyvinylidene fluoride or other piezoelectric materials in the practice of the present invention.

  As polylactic acid, depending on its crystal structure, poly-L-lactic acid obtained by polymerizing L-lactic acid and L-lactide, D-lactic acid, poly-D-lactic acid obtained by polymerizing D-lactide, and those There are stereocomplex polylactic acid having a hybrid structure, and any of them can be used as long as it exhibits piezoelectricity. From the viewpoint of high piezoelectricity, poly-L-lactic acid and poly-D-lactic acid are preferable. Since poly-L-lactic acid and poly-D-lactic acid are reversed in polarization with respect to the same stress, they can be used in combination according to the purpose.

  The optical purity of polylactic acid is preferably 99% or more, more preferably 99.3% or more, and further preferably 99.5% or more. If the optical purity is less than 99%, the piezoelectricity may be remarkably lowered, and it may be difficult to obtain a sufficient electrical signal due to the shape change of the piezoelectric fiber A. In particular, the piezoelectric fiber A preferably contains poly-L-lactic acid or poly-D-lactic acid as a main component, and the optical purity thereof is preferably 99% or more.

  The piezoelectric fiber A containing polylactic acid as a main component is drawn at the time of production and is uniaxially oriented in the fiber axis direction. Furthermore, the piezoelectric fiber A is not only uniaxially oriented in the fiber axis direction but also preferably contains polylactic acid crystals, and more preferably contains uniaxially oriented polylactic acid crystals. This is because polylactic acid exhibits higher piezoelectricity due to its high crystallinity and uniaxial orientation.

Crystallinity and uniaxial orientation are determined by homo-PLA crystallinity X homo (%) and crystal orientation Ao (%). As the piezoelectric fiber A of the present invention, it is preferable that the homo PLA crystallinity Xhomo (%) and the crystal orientation Ao (%) satisfy the following formula (1).
Xhomo × Ao × Ao ÷ 10 ⁶ ≧ 0.26 (1)

  If the above formula (1) is not satisfied, the crystallinity and / or uniaxial orientation may not be sufficient, and the output value of the electric signal for the operation may decrease, or the sensitivity of the signal for the operation in a specific direction may decrease. is there. The value on the left side of the formula (1) is more preferably 0.28 or more, and further preferably 0.3 or more. Here, each value is obtained according to the following.

Homopolylactic acid crystallinity Xhomo:
The homopolylactic acid crystallinity Xhomo is determined from crystal structure analysis by wide angle X-ray diffraction analysis (WAXD). In wide-angle X-ray diffraction analysis (WAXD), an X-ray diffraction pattern of a sample is recorded on an imaging plate under the following conditions by a transmission method using an Ultrax 18 type X-ray diffractometer manufactured by Rigaku.
X-ray source: Cu-Kα ray (confocal mirror)
Output: 45kV x 60mA
Slit: 1st: 1mmΦ, 2nd: 0.8mmΦ
Camera length: 120mm
Accumulation time: 10 minutes Sample: 35 mg of polylactic acid fibers are aligned to form a 3 cm fiber bundle.

In the obtained X-ray diffraction pattern, the total scattering intensity Itotal is obtained over the azimuth angle, and here, the integrated intensity of each diffraction peak derived from the homopolylactic acid crystal appearing in the vicinity of 2θ = 16.5 °, 18.5 °, 24.3 °. Is obtained as a sum ΣIHMi. From these values, the homopolylactic acid crystallinity Xhomo is determined according to the following formula (2).
Homopolylactic acid crystallinity X _homo (%) = ΣI _HMi / I _total × 100 (2)
Note that ΣI _HMi is calculated by subtracting diffuse scattering due to background and amorphous in the total scattering intensity.

Crystal orientation degree Ao:
Regarding the crystal orientation degree Ao, in the X-ray diffraction pattern obtained by the above wide-angle X-ray diffraction analysis (WAXD), the diffraction peak derived from the homopolylactic acid crystal appearing in the vicinity of 2θ = 16.5 ° in the radial direction is oriented. The intensity distribution with respect to the angle (°) is taken and calculated from the following formula (3) from the total ΣWi (°) of the half width of the obtained distribution profile.
Crystal orientation degree Ao (%) = (360−ΣWi) ÷ 360 × 100 (3)

  In addition, since polylactic acid is a polyester that is hydrolyzed relatively quickly, in the case where heat and humidity resistance is a problem, a known hydrolysis inhibitor such as an isocyanate compound, an oxazoline compound, an epoxy compound, or a carbodiimide compound is added. Also good. Further, if necessary, the physical properties may be improved by adding an antioxidant such as a phosphoric acid compound, a plasticizer, a photodegradation inhibitor, and the like.

  Polylactic acid may be used as an alloy with other polymers. However, if polylactic acid is used as the main piezoelectric polymer, it contains at least 50% by mass or more based on the total mass of the alloy. Preferably, it is 70 mass% or more, Most preferably, it is 90 mass% or more.

  Examples of the polymer other than polylactic acid in the case of alloy include polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate copolymer, polymethacrylate, and the like, but the invention is not limited thereto. Any polymer may be used as long as the desired piezoelectricity is exhibited.

  The piezoelectric fiber A may be a multifilament in which a plurality of filaments are bundled, or may be a monofilament composed of a single filament. In the case of monofilament (including spun yarn), the single yarn diameter is 1 μm to 5 mm, preferably 5 μm to 2 mm, and more preferably 10 μm to 1 mm. In the case of a multifilament, the single yarn diameter is 0.1 μm to 5 mm, preferably 2 μm to 100 μm, and more preferably 3 μm to 50 μm. The number of filaments of the multifilament is preferably 1 to 100,000, more preferably 50 to 50,000, and still more preferably 100 to 20,000. However, the fineness and the number of the piezoelectric fibers A are the fineness and the number per carrier when producing the braid, and the multifilament formed by a plurality of single yarns (monofilaments) is also one piezoelectric. It shall be counted as fiber A. Here, even if a fiber other than the piezoelectric fiber is used in one carrier, the total amount including that is used.

  In order to use such a piezoelectric polymer as the piezoelectric fiber A, any known technique for forming a fiber from the polymer can be employed as long as the effects of the present invention are exhibited. For example, a method of extruding a piezoelectric polymer to form a fiber, a method of melt-spinning a piezoelectric polymer to make a fiber, a method of making a piezoelectric polymer fiber by dry or wet spinning, a method of making a piezoelectric polymer A technique of forming fibers by electrostatic spinning, a technique of cutting thinly after forming a film, and the like can be employed. As these spinning conditions, a known method may be applied according to the piezoelectric polymer to be employed, and a melt spinning method that is industrially easy to produce is usually employed. Furthermore, after forming the fiber, the formed fiber is stretched. As a result, a piezoelectric fiber A that is uniaxially oriented and exhibits large piezoelectricity including crystals is formed.

  In addition, the piezoelectric fiber A can be subjected to treatments such as dyeing, twisting, blending, and heat treatment before making the braided braid as described above.

  Furthermore, since the piezoelectric fiber A may be broken when the braid is formed, the piezoelectric fiber A may be cut off or fluff may come out, so that the strength and wear resistance are preferably high. It is preferably 5 cN / dtex or more, more preferably 2.0 cN / dtex or more, further preferably 2.5 cN / dtex or more, and most preferably 3.0 cN / dtex or more. The abrasion resistance can be evaluated by JIS L1095 9.10.2 B method, etc., and the number of friction is preferably 100 times or more, more preferably 1000 times or more, and further preferably 5000 times or more. Most preferably, it is 10,000 times or more. The method for improving the wear resistance is not particularly limited, and any known method can be used. For example, the crystallinity is improved, fine particles are added, or the surface is processed. Can do. In addition, when processing into braids, a lubricant can be applied to the fibers to reduce friction.

Moreover, it is preferable that the shrinkage rate of the piezoelectric fiber is small from the shrinkage rate of the conductive fiber described above. If the difference in shrinkage rate is large, the braid may bend due to heat treatment during post-fabrication after fabric production or after fabric production or during actual use, or due to changes over time, the flatness of the fabric may deteriorate, or the piezoelectric signal will become weak. May end up. When the shrinkage rate is quantified by the boiling water shrinkage rate described later, it is preferable that the boiling water shrinkage rate S (p) of the piezoelectric fiber and the boiling water shrinkage rate S (c) of the conductive fiber satisfy the following formula (4). .
| S (p) −S (c) | ≦ 10 (4)
The left side of the above formula (4) is more preferably 5 or less, and even more preferably 3 or less.

Further, it is preferable that the contraction rate of the piezoelectric fiber is small in difference from the contraction rate of fibers other than the conductive fibers, for example, insulating fibers. If the difference in shrinkage rate is large, the braid may bend due to heat treatment during post-fabrication after fabric production or after fabric production or during actual use, or due to changes over time, the flatness of the fabric may deteriorate, or the piezoelectric signal will become weak. May end up. When the shrinkage rate is quantified by the boiling water shrinkage rate, it is preferable that the boiling water shrinkage rate S (p) of the piezoelectric fiber and the boiling water shrinkage rate S (i) of the insulating fiber satisfy the following formula (5).
| S (p) −S (i) | ≦ 10 (5)
The left side of the above formula (5) is more preferably 5 or less, and even more preferably 3 or less.

Further, it is preferable that the shrinkage rate of the piezoelectric fiber is small. For example, when the shrinkage rate is quantified by boiling water shrinkage rate, the shrinkage rate of the piezoelectric fiber is preferably 15% or less, more preferably 10% or less, further preferably 5% or less, and most preferably 3% or less. is there. As a means for lowering the shrinkage rate, any known method can be applied. For example, the shrinkage rate can be reduced by relaxing the orientation of the amorphous part or increasing the crystallinity by heat treatment, and the heat treatment is performed. The timing is not particularly limited, and examples thereof include after stretching, after twisting, after braiding, and after forming into a fabric. In addition, the above-mentioned boiling water shrinkage shall be measured with the following method. A casserole of 20 times was made with a measuring machine having a frame circumference of 1.125 m, a load of 0.022 cN / dtex was applied, it was hung on a scale plate, and the initial casket length L0 was measured. After that, this casserole was treated in a boiling water bath at 100 ° C. for 30 minutes, allowed to cool, and again subjected to the above load and hung on the scale plate to measure the length L after shrinkage. Using the measured L0 and L, the boiling water shrinkage is calculated by the following equation (6).
Boiling water shrinkage = (L0−L) / L0 × 100 (%) (6)

(Coating)
The surface of the conductive fiber B, that is, the core portion 3 is covered with the piezoelectric fiber A, that is, the braided sheath portion 2. The thickness of the sheath part 2 covering the conductive fiber B is preferably 1 μm to 10 mm, more preferably 5 μm to 5 mm, further preferably 10 μm to 3 mm, most preferably 20 μm to 1 mm. preferable. If it is too thin, there may be a problem in terms of strength. If it is too thick, the braided piezoelectric element 1 may become hard and difficult to deform. In addition, the sheath part 2 said here refers to the layer adjacent to the core part 3. FIG.

  In the braided piezoelectric element 1, the total fineness of the piezoelectric fibers A in the sheath 2 is preferably not less than 1/2 times and not more than 20 times the total fineness of the conductive fibers B in the core 3. 15 times or less, more preferably 2 times or more and 10 times or less. If the total fineness of the piezoelectric fiber A is too small relative to the total fineness of the conductive fiber B, the piezoelectric fiber A surrounding the conductive fiber B is too small and the conductive fiber B cannot output a sufficient electrical signal, Furthermore, there exists a possibility that the conductive fiber B may contact the other conductive fiber which adjoins. If the total fineness of the piezoelectric fiber A is too large relative to the total fineness of the conductive fiber B, there are too many piezoelectric fibers A surrounding the conductive fiber B, and the braided piezoelectric element 1 becomes hard and difficult to deform. That is, in any case, the braided piezoelectric element 1 does not sufficiently function as a sensor.

  The total fineness referred to here is the sum of the finenesses of all the piezoelectric fibers A constituting the sheath portion 2. For example, in the case of a general 8-strand braid, it is the sum of the finenesses of 8 fibers.

  In the braided piezoelectric element 1, the fineness per piezoelectric fiber A of the sheath 2 is preferably 1/20 or more and 2 or less the total fineness of the conductive fiber B. It is more preferably 15 times or more and 1.5 times or less, and further preferably 1/10 time or more and 1 time or less. If the fineness per piezoelectric fiber A is too small relative to the total fineness of the conductive fiber B, the piezoelectric fiber A is too small and the conductive fiber B cannot output a sufficient electric signal. May break. If the fineness per piezoelectric fiber A is too large relative to the total fineness of the conductive fiber B, the piezoelectric fiber A is too thick and the braided piezoelectric element 1 becomes hard and difficult to deform. That is, in any case, the braided piezoelectric element 1 does not sufficiently function as a sensor.

  In addition, when a metal fiber is used for the conductive fiber B, or when the metal fiber is mixed with the conductive fiber A or the piezoelectric fiber B, the fineness ratio is not limited to the above. This is because, in the present invention, the ratio is important in terms of contact area and coverage, that is, area and volume. For example, when the specific gravity of each fiber exceeds 2, it is preferable that the ratio of the average cross-sectional area of the fiber is the ratio of the fineness.

  Although it is preferable that the piezoelectric fiber A and the conductive fiber B are as close as possible, an anchor layer or an adhesive layer is provided between the conductive fiber B and the piezoelectric fiber A in order to improve the adhesiveness. May be.

  The covering method is a method in which the conductive fiber B is used as a core yarn, and the piezoelectric fiber A is wound around in a braid shape around the conductive fiber B. On the other hand, the shape of the braid of the piezoelectric fiber A is not particularly limited as long as an electric signal can be output with respect to the stress generated by the applied load. A braided string is preferred.

  The shape of the conductive fiber B and the piezoelectric fiber A is not particularly limited, but is preferably as close to a concentric circle as possible. When a multifilament is used as the conductive fiber B, the piezoelectric fiber A only needs to be covered so that at least a part of the surface (fiber peripheral surface) of the multifilament of the conductive fiber B is in contact. The piezoelectric fibers A may or may not be coated on all filament surfaces (fiber peripheral surfaces) constituting the multifilament. What is necessary is just to set suitably the covering state of the piezoelectric fiber A to each internal filament which comprises the multifilament of the conductive fiber B, considering the performance as a piezoelectric element, the handleability, etc.

  The braided piezoelectric element 1 of the present invention does not need to have an electrode on the surface thereof, so that there is no need to further cover the braided piezoelectric element 1 itself, and there is an advantage that malfunction is unlikely.

(Production method)
In the braided piezoelectric element 1 of the present invention, the surface of at least one conductive fiber B is covered with the braided piezoelectric fiber A. Examples of the manufacturing method include the following methods. In other words, the conductive fiber B and the piezoelectric fiber A are produced in separate steps, and the conductive fiber B is wrapped around the conductive fiber B in a braid shape and covered. In this case, it is preferable to coat so as to be as concentric as possible.

  In this case, as preferred spinning and stretching conditions when polylactic acid is used as the piezoelectric polymer for forming the piezoelectric fiber A, the melt spinning temperature is preferably 150 ° C. to 250 ° C., and the stretching temperature is preferably 40 ° C. to 150 ° C. The draw ratio is preferably 1.1 to 5.0 times, and the crystallization temperature is preferably 80 ° C to 170 ° C.

  As the piezoelectric fiber A wound around the conductive fiber B, a multifilament in which a plurality of filaments are bundled may be used, or a monofilament (including spun yarn) may be used. In addition, as the conductive fiber B around which the piezoelectric fiber A is wound, a multifilament in which a plurality of filaments are bundled may be used, or a monofilament (including spun yarn) may be used.

  As a preferable form of the coating, the conductive fiber B can be used as a core yarn, and the piezoelectric fiber A can be formed in a braid shape around the conductive fiber B to form a round braid. . More specifically, an 8-strand braid having 16 cores and a 16-strand braid are included. However, for example, the piezoelectric fiber A may be shaped like a braided tube, and the conductive fiber B may be used as a core and inserted into the braided tube.

By the manufacturing method as described above, the braided piezoelectric element 1 in which the surface of the conductive fiber B is covered with the braided piezoelectric fiber A can be obtained.
Since the braided piezoelectric element 1 of the present invention does not require the formation of an electrode for detecting an electric signal on the surface, it can be manufactured relatively easily.

(Protective layer)
A protective layer may be provided on the outermost surface of the braided piezoelectric element 1 of the present invention. This protective layer is preferably insulative, and more preferably made of a polymer from the viewpoint of flexibility. In the case of providing the protective layer with insulation, of course, in this case, the entire protective layer is deformed or rubbed on the protective layer, but these external forces reach the piezoelectric fiber A, There is no particular limitation as long as it can induce polarization. The protective layer is not limited to those formed by coating with a polymer or the like, and may be a film, fabric, fiber or the like, or a combination thereof.

  The thinner the protective layer is, the easier it is to transmit shear stress to the piezoelectric fiber A. However, if it is too thin, problems such as destruction of the protective layer itself are likely to occur, and preferably 10 nm to 200 μm. More preferably, they are 50 nm-50 micrometers, More preferably, they are 70 nm-30 micrometers, Most preferably, they are 100 nm-10 micrometers. The shape of the piezoelectric element can also be formed by this protective layer.

It is also possible to incorporate an electromagnetic shielding layer into the braid structure for the purpose of noise reduction. The electromagnetic wave shielding layer is not particularly limited, but may be coated with a conductive substance, or may be wound with a conductive film, fabric, fiber, or the like. The volume resistivity of the electromagnetic wave shielding layer is preferably 10 ⁻¹ Ω · cm or less, more preferably 10 ⁻² Ω · cm or less, and still more preferably 10 ⁻³ Ω · cm or less. However, the resistivity is not limited as long as the effect of the electromagnetic wave shielding layer can be obtained. This electromagnetic wave shielding layer may be provided on the surface of the piezoelectric fiber A of the sheath, or may be provided outside the protective layer described above. Of course, a plurality of layers of electromagnetic shielding layers and protective layers may be laminated, and the order thereof is appropriately determined according to the purpose.

  Furthermore, a plurality of layers made of piezoelectric fibers can be provided, or a plurality of layers made of conductive fibers for extracting signals can be provided. Of course, the order and the number of layers of these protective layers, electromagnetic wave shielding layers, layers made of piezoelectric fibers, and layers made of conductive fibers are appropriately determined according to the purpose. In addition, as a method of winding, the method of forming a braid structure in the outer layer of the sheath part 2, or covering it is mentioned.

(Function)
The braided piezoelectric element 1 of the present invention has the magnitude and / or position of the stress generated when a load is applied to the braided piezoelectric element 1 by the swallowing operation, that is, the stress applied to the braided piezoelectric element 1. It can be used as a sensor to detect.

(Configuration of swallowing detection sensor)
The swallowing detection sensor of the present invention is a fiber structure that can be attached to the neck. At that time, the swallowing detection sensor includes at least one braided piezoelectric element 1, and there is no limitation as long as the braided piezoelectric element 1 can function as a piezoelectric element. There may be. In forming the fabric, as long as the object of the present invention is achieved, it may be combined with other fibers (including braids) to perform weaving, knitting and the like. The braided piezoelectric element 1 may be used as a part of a fiber (for example, warp or weft) constituting the fabric, or the braided piezoelectric element 1 may be embroidered or bonded to the fabric. Examples of the woven structure of the fabric include a three-layer structure such as plain weave, twill weave, and satin weave, a change structure, a single double structure such as a vertical double weave and a horizontal double weave, and a vertical velvet. The type of knitted fabric may be a circular knitted fabric (weft knitted fabric) or a warp knitted fabric. Among the fabrics, preferred examples of the structure of the circular knitted fabric (weft knitted fabric) include a flat knitted fabric, a rubber knitted fabric, a double-sided knitted fabric, a pearl knitted fabric, a tucked knitted fabric, a floating knitted fabric, a single-sided knitted fabric, a lace knitted fabric, and a spliced knitted fabric. Examples of the warp knitting structure include single denby knitting, single atlas knitting, double cord knitting, half tricot knitting, back hair knitting, jacquard knitting, and the like. The number of layers may be a single layer or a multilayer of two or more layers. Further, it may be a napped woven fabric or a napped knitted fabric composed of a napped portion made of a cut pile and / or a loop pile and a ground tissue portion.

  A plurality of braided piezoelectric elements 1 can be arranged and used. The arrangement method is not particularly limited, but if it is arranged in a straight line in the horizontal direction at the time of use, the vertical movement of the neck, that is, the swallowing movement is taken out by taking out the electric signal of each braided piezoelectric element. It is possible to grasp the situation in detail. The number of braided piezoelectric elements in that case is not particularly limited, but is preferably 2 or more, 15 or less, more preferably 3 or more and 12 or less, and more preferably 3 or more and 10 or less. More preferred. The range in which the braided piezoelectric element is arranged in the vertical direction during use is not particularly limited as long as it is narrower than the length of the neck and can be detected by swallowing motion. The intervals between the braided piezoelectric elements may be equal intervals or not.

  The method of fixing the swallowing detection sensor to the neck is not particularly limited, but male and female hooks with different fasteners are attached to both ends of the sensor, and males and females are stacked and stopped at the back of the neck, or rubber is attached to both ends of the sensor. You can take measures such as stopping using the tension. In any case, a method in which the swallowing detection sensor can be reliably fixed to the neck, is less uncomfortable when worn, and is easy to attach and detach is more preferably used.

(Insulating fiber)
In the swallowing detection sensor, insulating fibers can be used for portions other than the braided piezoelectric element 1 (and the conductive fibers 8). At this time, the insulating fiber may be a stretchable material or a fiber having a shape for the purpose of improving the flexibility of the swallowing detection sensor.

  As described above, by arranging the insulating fibers in addition to the braided piezoelectric element 1 (and the conductive fibers 8), the operability of the swallowing detection sensor (eg, ease of movement as a swallowing detection sensor) is improved. It is possible.

As such an insulating fiber, it can be used if the volume resistivity is 10 ⁶ Ω · cm or more, more preferably 10 ⁸ Ω · cm or more, and further preferably 10 ¹⁰ Ω · cm or more.

Insulating fibers such as polyester fibers, nylon fibers, acrylic fibers, polyethylene fibers, polypropylene fibers, vinyl chloride fibers, aramid fibers, polysulfone fibers, polyether fibers, polyurethane fibers, etc., cotton, hemp, silk, etc. Natural fibers, semi-synthetic fibers such as acetate, and regenerated fibers such as rayon and cupra can be used. It is not limited to these, A well-known insulating fiber can be used arbitrarily. Furthermore, these insulating fibers may be used in combination, or may be combined with a fiber having no insulating property to form a fiber having insulating properties as a whole.
Also, any known cross-sectional shape fiber can be used.

(Applied technology of swallowing detection sensor)
The piezoelectric element of the present invention can output contact, pressure, and shape change of the surface as an electrical signal in any form, so that the magnitude and / or applied stress applied to the piezoelectric element can be output. It can be used as a swallowing detection sensor for detecting the position.

  The method of using the swallowing detection sensor is not particularly limited, but it can measure the number of swallowing that can serve as an index of swallowing function decline, and can measure the movement of the laryngeal protuberance (generally referred to as “throat throat”). For example, the piezoelectric element part of the swallowing detection sensor is brought into contact with the position of the laryngeal protuberance, and processing such as integration is performed on the output signal of the piezoelectric element over time, so that the laryngeal protuberance moves vertically with time. The displacement of can be captured. Furthermore, when a plurality of piezoelectric elements are arranged in the horizontal direction during use, the displacement of the laryngeal protuberance in parallel to the skin of the laryngeal protuberance can be captured from the positional relationship of the piezoelectric elements and the respective output signals, and the movement of the laryngeal protuberance can be detected. A measurement profile displayed in three dimensions can be obtained. The fact that the movement of the laryngeal ridge can be captured in detail even during an extremely short swallowing operation of around 0.5 seconds is a feature of using a piezoelectric element with very fast response.

Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.
The fabric for piezoelectric elements was manufactured by the following method.

(Manufacture of polylactic acid)
The polylactic acid used in the examples was produced by the following method.
To 100 parts by mass of L-lactide (manufactured by Musashino Chemical Laboratory, Inc., optical purity 100%), 0.005 part by mass of tin octylate was added, and 180 ° C. in a reactor equipped with a stirring blade in a nitrogen atmosphere. Then, 1.2 times equivalent of phosphoric acid was added to tin octylate, and then the remaining lactide was removed under reduced pressure at 13.3 Pa to obtain chips to obtain poly-L-lactic acid (PLLA1). . The obtained PLLA1 had a mass average molecular weight of 152,000, a glass transition point (Tg) of 55 ° C., and a melting point of 175 ° C.

(Piezoelectric fiber)
PLLA1 melted at 240 ° C. was discharged from a 24-hole cap at 20 g / min and taken up at 887 m / min. This unstretched multifilament yarn was stretched 2.3 times at 80 ° C. and heat-set at 100 ° C. to obtain a multifilament uniaxially stretched yarn of 84 dTex / 24 filament.

(Conductive fiber)
Silver-plated nylon manufactured by Mitsufuji Corporation, product name “AGposs” 100d34f was used as the conductive fiber B. The volume resistivity of this fiber was 1.1 × 10 ⁻³ Ω · cm.

(Insulating fiber)
Polyethylene terephthalate melted at 280 ° C. was discharged from a 24-hole cap at 45 g / min and taken up at 800 m / min. This undrawn yarn was drawn at 80 ° C. and 2.5 times, and heat-fixed at 180 ° C. to obtain a multifilament drawn yarn of 84 dTex / 24 filament, which was used as an insulating fiber.

(Braided piezoelectric element)
As a sample of Example 1, as shown in FIG. 1, the conductive fiber B is used as a core yarn, and the eight piezoelectric fibers A are wound around the core yarn in a braid shape to form an eight-ply braid. A braided piezoelectric element 1 was formed. Here, the winding angle α of the piezoelectric fiber A with respect to the fiber axis CL of the conductive fiber B was 45 °.

(Swallowing detection sensor)
As a sample of Example 1, 10 cords of braided piezoelectric elements 1 having a length of 130 mm in parallel at equal intervals of 4 mm are provided in the center of a 160 mm × 50 mm polyester fabric (100% polyester knitted fabric). A swallowing detection sensor sample 10-1 including a braided piezoelectric element fixed by embroidery and having a fixing Velcro (registered trademark) attached to both ends in the longitudinal direction of the polyester fabric was prepared.
In addition, as a sample of Example 2, three swallowing detection sensor samples 10-1 each having a braided piezoelectric element in which a rubber string was attached to the end of the braided piezoelectric element 1 having a length of 130 mm were prepared.

(Performance evaluation and evaluation results)
The performance evaluation and evaluation results of the swallowing detection sensor samples 10-1 and 10-2 are as follows.

[Example 1]
Using the conductive fibers B in the ten braided piezoelectric elements of the swallowing detection sensor sample 10-1 as signal lines, wiring is made to an oscilloscope (Yokogawa Electric's digital oscilloscope DL6000 series product name "DL6000"). Connected via an amplifier circuit. Using a model test device that simulates swallowing, a terminal (height 8 mm) attached to the actuator was moved linearly for 0.2 seconds, stopped for 0.1 seconds, and then turned in the opposite direction. Measurement was performed on the output signal of the swallowing detection sensor sample 10-1, which was fixed with Velcro (registered trademark) so as to come into contact with the cloth imitating the skin, which was moved by the terminal during that time and was subjected to pressure in the meantime. .

  As a result, the displacement of movement of the laryngeal protuberance perpendicular to the skin calculated from the elapsed time (Y-axis) and the integrated value of the output signals obtained from the ten piezoelectric elements in the braided piezoelectric element fixed sample 10-1. (Re axis) By plotting the displacement (X axis) of the laryngeal protuberance in parallel with the laryngeal protuberance calculated from the positional relationship of the 10 piezoelectric elements, it is related to an extremely short time of 0.5 seconds. First, the three-dimensional measurement profile that captured the detailed movement shown in FIG. 5 was obtained.

[Example 2]
Each conductive fiber B in the three braided piezoelectric elements of the swallowing detection sensor sample 10-2 is used as a signal line through an oscilloscope (digital oscilloscope DL6000 series product name "DL6000" manufactured by Yokogawa Electric Corporation) via wiring. Connected via an amplifier circuit. Three swallowing detection sensor samples 10-2 were worn so that subjects in their early 60s were equally spaced in the range of about 4 cm near the laryngeal protuberance, and the output signal when drinking water was measured. . There was no discomfort such as pain when worn.

  As a result, the displacement (Re) of the laryngeal protuberance and the vertical movement calculated from the elapsed time (Y axis) and the integrated value of the output signals obtained from the three piezoelectric elements in the swallowing detection sensor sample 10-2. Axis) By plotting the displacement of the laryngeal protuberance and the movement in the direction parallel to the laryngeal protuberance (X-axis) calculated from the positional relationship of the 10 piezoelectric elements, the swallowing motion for an extremely short time of about 0.5 seconds is plotted. In spite of the above, a three-dimensional measurement profile capturing the detailed movement shown in FIG. 6 was obtained.

  FIG. 6 is a measurement profile having horseshoe-like features similar to those in FIG. 5, and it was found that the features of the laryngeal protuberance were captured.

  According to the present invention, there is provided a swallowing detection sensor and a swallowing detection system using the sensor that are easy to measure and can accurately measure more information without adversely affecting the human body. Is extremely large.

DESCRIPTION OF SYMBOLS 10 Piezoelectric element 12 Amplifying means 13 Output means 21 Fixing Velcro (registered trademark)

Claims (14)

  A swallowing detection sensor comprising a fibrous structure that can be attached to a neck.   The swallowing detection sensor according to claim 1, comprising a string-like piezoelectric element.   The swallowing detection sensor according to claim 2, wherein the piezoelectric element is a braided piezoelectric element.   The braided piezoelectric element includes a core portion formed of conductive fiber and a sheath portion formed of braided piezoelectric fiber so as to cover the core portion, and the piezoelectric fiber is a main component 4. The swallowing detection sensor according to claim 3, wherein the wrapping angle of the piezoelectric fiber with respect to the conductive fiber is 15 ° or more and 75 ° or less.   The swallowing detection sensor according to claim 3, wherein the total fineness of the piezoelectric fiber is ½ times or more and 20 times or less of the total fineness of the conductive fiber.   The swallowing detection sensor according to claim 3, wherein the fineness per piezoelectric fiber is 1/20 or more and 2 or less of the total fineness of the conductive fiber.   The swallowing detection sensor according to claim 2, wherein two or more string-like piezoelectric elements are used.   The swallowing detection sensor according to claim 2, wherein the string-like piezoelectric element is arranged in a horizontal direction when in use.   The swallowing detection sensor according to any one of claims 2 to 8, wherein the string-like piezoelectric element is fixed to a fiber structure.   The swallowing detection sensor according to claim 9, wherein the string-like piezoelectric element is fixed to the fiber structure with an adhesive substance.   The swallowing detection sensor according to claim 9, wherein the string-like piezoelectric element is fixed to the fiber structure by sewing.   The swallowing detection sensor according to claim 9, wherein the string-like piezoelectric element is part of a fiber structure.   A swallowing detection system using the swallowing detection sensor according to claim 1.   The swallowing detection system according to claim 13, wherein the swallowing detection sensor is used to detect a temporal change in the position of the pharyngeal elevation.