JP2007252420A - Human body muscle evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To noninvasively evaluate human body muscles under the skin by polarization. <P>SOLUTION: The human body muscle evaluation device estimates the condition of the muscles of a human body by irradiating the muscles of the human body with light and analyzing transmitted or reflected light. The device comprises a polarized light irradiation means for irradiating the skin of the human body with polarized light, a polarized light measurement means for measuring the light quantity distribution of a polarization angle for the light transmitted through or reflected from the human body, and an analysis means for estimating the condition of the muscles under the skin of the human body by analyzing the light quantity distribution of the polarization angle. The human body muscles are evaluated by utilizing polarization properties that muscle tissue itself has. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a human body muscle evaluation apparatus that non-invasively evaluates human body muscles under the skin using light.

  Various types of non-invasive measurement of the state of the human body by irradiating the human body with light are provided, and in particular for using polarized light, the angle of the plane of polarization of transmitted light by applying a magnetic field to the living body. Patent Document 1 discloses that hemoglobin is measured by measuring a change, and Patent Document 2 discloses that a glucose concentration is measured by analyzing an optical rotation angle of a linearly polarized light component.

However, the former does not use the intrinsic polarization characteristics of the tissue, and the latter uses the polarization phenomenon of specific components in the body, and these affect the polarization of human muscles under the skin. There is no description of the impact.
JP-A-4-194729 JP 2004-113434 A

  The present invention has been invented in view of the above-described conventional problems, and an object of the present invention is to provide a human body muscle evaluation apparatus that non-invasively evaluates human body muscles under the skin using polarized light.

  In order to solve the above problems, the human body muscle evaluation apparatus according to the present invention is a human body muscle evaluation apparatus that estimates the state of the human muscle by irradiating the muscle of the human body with light and analyzing the transmitted or reflected light. A polarized light irradiating means for irradiating the human skin with polarized light; a polarization measuring means for measuring the light quantity distribution of the polarization angle of the light transmitted or reflected by the human body; and analyzing the light quantity distribution of the polarization angle under the skin of the human body. And an analysis means for estimating the state of the muscle.

  This is based on the following knowledge. That is, the sample is irradiated with laser light that is linearly polarized light, and the light transmitted through the sample is received by the light receiving element through the polarizing plate (linear polarizing plate), and the polarizing plate is rotated by a rotating stage in 2 ° steps. When rotated, the relative light intensity data shown in FIG. 2 could be obtained. Here, chicken breast (thickness 1.3 mm, 2.6 mm, 3.9 mm) was used as a sample. When ◇ is 1.3 mm in the figure, □ is 2.6 mm in thickness and Δ is In the case of a thickness of 3.9 mm, ◯ indicates a case where laser light is directly received without passing through a sample.

  The vertical axis in FIG. 2 indicates the relative light intensity (light quantity), and the intensity 1 is the received light quantity when there is no polarizing plate on the light receiving side. Since the laser light is linearly polarized light, the amount of received light changes in a sine curve with the rotation of the polarizing plate. And the change in the amount of light transmitted through the chicken breast (muscle) is out of phase as well as the amount of light compared to the case where it does not pass through the sample (○ in the figure). It can be seen that the polarization angle change occurs. In other words, it can be seen that the muscle tissue itself has polarization characteristics. The reason for having such a polarization characteristic is not clear, but the present invention uses this point to evaluate human muscles.

  At this time, if the polarized light irradiating means irradiates light having a wavelength of 500 nm to 2000 nm, it is difficult to be absorbed by blood, and therefore it is difficult to be influenced by blood, so that the estimation accuracy can be improved.

  Further, if the polarized light irradiating means emits light of a plurality of types of wavelengths, the estimation accuracy can be improved by analyzing in consideration of the types of irradiation wavelengths.

  Moreover, if the polarized light irradiating means irradiates the line-shaped light, it is possible to reduce the possibility of a biased analysis because the irradiation site can be widened, and therefore the estimation accuracy can be improved. it can.

  The polarized light irradiating means emits pulsed light, the polarized light measuring means measures the time change of the light distribution of the polarization angle, and the analyzing means analyzes the light distribution of the polarization angle in consideration of the time change. It is preferable. The estimation accuracy can be improved by analyzing in consideration of the time change.

  If the analysis means removes the influence of the skin or the nail from the light distribution data of the polarization angle by the skin or the nail measured in advance, the influence of the polarization by the skin or the nail can be removed. The accuracy of estimating the state can be improved.

  In the present invention, the state of the human muscle is analyzed and evaluated non-invasively using light that can be obtained very easily, such as polarized light, and information such as the degree of fatigue and body age can be easily obtained. .

  Hereinafter, the present invention will be described based on an embodiment. FIG. 1 shows an example of an embodiment of the present invention. A light source 1 capable of irradiation time control, and light emitted from the light source 1 is converted into linearly polarized light. A polarizing plate 2 that passes through the polarizing plate 2, a light receiving element 4 that receives reflected or transmitted light when the surface of the human body 9 is irradiated with light that has been linearly polarized, and is disposed immediately before the light receiving element 4. The polarizing plate 3, the rotating stage 5 that rotates the polarizing plate 3 around the optical axis by motor driving, the light amount measurement data obtained from the light receiving element 4, and the polarization angle control when the polarizing plate 3 is rotated by the rotating stage 5 Analyzing means 6 for performing analysis based on polarization angle light quantity distribution data, which is light quantity data for each polarization angle composed of data. The polarized light irradiation means composed of the light source 1 and the polarizing plate 2 may be constituted by a laser light output means.

  As the light source 1, light having a wavelength in the range of 500 to 2000 nm can be suitably used. As shown in FIG. 3, the absorbance of blood existing under the skin of the human body 9, particularly oxyhemoglobin, has a peak at 500 nm or less, so that the light absorption of blood vessels in the dermis layer is caused by noise by using light of the above wavelength. Can be avoided.

  Then, the light amount for each polarization angle is measured while switching the polarization angle of the polarizing plate 3 disposed in front of the light receiving element 4 to obtain the polarization angle light amount distribution data. Therefore, the muscle condition is analyzed and evaluated.

  Here, the light irradiated to the human body 9 by the polarized light irradiation means is reflected on the skin surface or reflected inside the muscle, but the light reflected on the skin surface has the same polarization angle as the irradiated linearly polarized light component. Therefore, the light reflected from the skin surface can be ignored by excluding light having the same polarization angle.

  Further, when the amount of light decrease in the depth direction of the muscle transmitted through the muscle was measured using a plurality of wavelengths, as shown in FIG. It becomes. In the figure, a indicates a case of measurement using light of 670 nm wavelength and chicken (sasami), wavelength of 670 nm and pork, and wavelength of 810 nm and chicken.

  Further, FIG. 5 shows the results of measuring the light amount decrease in the muscle depth direction (1 mm, 2 mm, 3 mm, and 4 mm) for two lights (vertical polarized light and horizontal polarized light) having orthogonal polarization angles while changing the incident angle. . The vertical axis represents the relative light intensity, and the intensity 1 represents the amount of received light when there is no polarizing plate on the light receiving side. 8 types of data: horizontal and vertical polarization at 1 mm depth, horizontal and vertical polarization at 2 mm depth, horizontal and vertical polarization at 3 mm depth, horizontal and vertical polarization at 4 mm depth Although the relative light intensity of horizontal polarization and vertical polarization is substantially the same at each incident angle, the specific muscular tissue shows a certain tendency of the polarization angle regardless of its thickness. I understand that.

  Based on these points, when evaluating the state of the muscle, as described above, the reflected light from the skin surface has the same angle as the irradiated linearly polarized light, and thus the light quantity data at this angle is excluded. In addition, it is necessary to eliminate the influence of the subcutaneous tissue, but this is dealt with by examining in advance the polarization angle characteristics of each component of the subcutaneous tissue that passes through the stratum corneum, dermis layer, and fat layer to the internal tissue. be able to.

For example, the amount of light irradiated is L0, the reflected light on the skin surface is La, and the polarization angle and light amount of each component are the stratum corneum: polarization angle = α1, light amount value = L1
Dermal layer: polarization angle = α2, light quantity value = L2
Fat layer: polarization angle = α3, light quantity value = L3
, The light quantity reduction rate due to the difference in the distance that the light has passed (distance in the depth direction) shows the characteristics as shown in FIG.
The stratum corneum thickness: estimated from the light quantity reduction rate obtained by L1 / (L0-La) The dermis layer thickness: estimated from the light quantity reduction rate obtained by L2 / (L0-La): L3 / (L0- The thickness of each layer can be obtained by estimation from the light amount reduction rate obtained in La).

As for the fingertip, there is almost no stratum corneum and there is a nail instead.Thus, the polarization angle data of the nail is excluded, and the thickness measurement of the subcutaneous tissue of the fingertip can be performed by measuring the light amount decrease by the nail in advance. it can. By the way, if the light intensity reduction rate by the nail is k,
The stratum corneum layer thickness: Estimated from the light intensity reduction rate obtained by L1 / (L0−La) × 1 / k The dermis layer thickness: Estimated from the light intensity reduction rate obtained by L2 / (L0−La) × 1 / k Thickness: The thickness of each layer can be obtained by estimation from the light amount reduction rate obtained by L3 / (L0−La) × 1 / k.

  In addition, as for the influence of blood vessels, it is cut at the stage of irradiation as described above, but the subcutaneous tissue constituents absorb light of a specific wavelength, so this effect causes a light quantity decrease other than a light quantity decrease due to thickness There is. In particular, an extremely thin layer such as a stratum corneum is particularly affected because the decrease in the amount of light due to the thickness is small. For this reason, it is preferable to reduce the thickness estimation error as much as possible by examining the absorption wavelength of the stratum corneum in advance and cutting the absorption wavelength from the wavelength of the irradiation light source. Specifically, since melanin causes light absorption having a peak at 567 nm (see FIG. 6), the influence of light absorption of melanin can be avoided by using polarized light with a wavelength of 1000 nm or more.

  In addition, when irradiating polarized light, the structure in the line direction can be estimated by irradiating linear light and receiving light by a two-dimensional light receiving element 4 such as a CCD. The polarized light to be irradiated may be spot light, and the light may be scanned with a mirror to perform two-dimensional irradiation on the skin surface to perform three-dimensional structure estimation.

  Further, the muscle state evaluation based on the polarization angle light amount distribution data is not limited to a static one, and the dynamic state can also be evaluated by using the polarization angle light amount distribution data including temporal changes. In this case, after determining the polarization angle on the light-receiving side to be the optimum angle for measuring the muscle state, the irradiation light source is set to pulsed light, and measurement is performed in synchronization with this irradiation timing to measure thickness changes due to muscle expansion and contraction. can do.

  When using polarized light irradiation means and light receiving element 4 that can use all light having a wavelength distributed within a certain range, rather than using only light having a certain wavelength, the irradiation wavelength distribution is You may make it analyze in consideration.

  The analysis evaluation by the analysis means 6 is not limited to the evaluation of the muscle state (stretching degree, fatigue degree, etc.). For example, there is a stiff shoulder as an effect of stress, but the stiff shoulder caused by poor circulation of muscles is in a state where muscle contraction does not occur much. Therefore, the degree of stress can be measured and evaluated from the stiff shoulder, which is an alternative phenomenon of stress, by irradiating the shoulder portion of the human body 9 with polarized light and monitoring the contraction of the shoulder muscle tissue.

It is a block diagram of an example of an embodiment of the invention. It is explanatory drawing which shows the relative light intensity for every polarization angle by a muscle. It is explanatory drawing of the light absorbency of oxyhemoglobin. It is explanatory drawing of the light quantity fall inside a muscle. It is explanatory drawing which shows the relative light intensity for every polarization angle inside a muscle. It is explanatory drawing of the light absorbency of melanin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Polarizing plate 3 Polarizing plate 4 Light receiving element 5 Rotating stage 6 Analysis means

Claims (6)

  A human muscle evaluation apparatus that estimates the state of a human muscle by irradiating light to the human muscle and analyzing the transmitted or reflected light, a polarized light irradiation means for irradiating the human skin with polarized light, and the human body Polarization measuring means for measuring the light amount distribution of the polarization angle with respect to the light transmitted or reflected, and an analysis means for analyzing the light amount distribution of the polarization angle to estimate the state of muscles under the skin of the human body Human body muscle evaluation device.   2. The human muscle evaluation apparatus according to claim 1, wherein the polarized light irradiation means irradiates light having a wavelength of 500 nm to 2000 nm.   The human body muscle evaluation apparatus according to claim 1 or 2, wherein the polarized light irradiation means irradiates light of a plurality of types of wavelengths.   The human body muscle evaluation apparatus according to any one of claims 1 to 3, wherein the polarized light irradiation means irradiates line-shaped light.   The polarized light irradiating means irradiates pulsed light, the polarized light measuring means measures the time change of the light amount distribution of the polarization angle, and the analyzing means analyzes the light amount distribution of the polarization angle in consideration of the time change. The human body muscle evaluation apparatus according to any one of claims 1 to 4, wherein the apparatus is a human muscle evaluation apparatus.   6. The analysis device according to claim 1, wherein the analysis unit performs an analysis by removing the influence of the skin or the nail from the light amount distribution data of the polarization angle of the skin or the nail measured in advance. Human muscle evaluation device.

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