JP2845583B2 - Method and apparatus for measuring mechanical properties of living body surface and structure of vibrator with built-in sensor - Google Patents

Description

Detailed Description of the Invention [Table of Contents] Industrial application Field of the Invention Prior Art Problems to be Solved by the Invention Means for Solving the Problems Working Examples Configuration of Device (FIGS. 3 and 4) Structure Mechanical properties excluding the influence of dependence A. Experiments on models (1) Experimental method (Fig. 5) (2) Evaluation of structural dependence (Fig. 6) (3) Determination of correction function (Fig. 7) (4) When the medium constants are different (Fig. 8, Fig. 9, Fig. 10
(Figure) (5) When measurement conditions are different (Fig. 11, Fig. 12,
(6) Application of correction function (Fig. 14, Fig. 15, Fig. 16,
(Fig. 17) B. Measurement of mechanical properties around eyelid and its analysis (1) Measurement of mechanical properties around eyelid (Figs. 18, 19,
(Fig. 20) (2) Application of correction function (Fig. 21) (3) Device (Fig. 22, Fig. 23, Fig. 24) Mechanical properties including structural dependence A. Measurement of biomechanical impedance and hardness Indicators (No. 25
(Figure) (1) Index of hardness (Fig. 26, Fig. 27) (2) Index of mechanical impedance and hardness (Fig. 28,
(Fig. 29) B. Mapping of hardness by mechanical impedance (1) Bar model (Fig. 14, Fig. 15, Fig. 30) (2) Block model (Fig. 31, Fig. 32, Fig. 33) SI mapping of biomechanical impedance (1) Back of hand (Fig. 34, Fig. 35, Fig. 36) (2) Chest (Fig. 37, Fig. 38, Fig. 39) D. Hardness index and palpation ( 1) Experimental method and results (FIGS. 40, 41, 42)
Figure) Effect of the Invention [Industrial Application Field] The present invention relates to the mechanical properties of the surface of a living body, in particular, the elastic and viscous coefficients of the skin tissue of the living body, and the mechanical properties of the biological surface empirically obtained by palpation. TECHNICAL FIELD The present invention relates to a method and apparatus for measuring an evaluation index capable of objectively evaluating an image sensor, and a structure of a vibrator with a built-in sensor used therein.

[Conventional technology]

If parameters that represent the mechanical properties of the skin tissue itself can be measured, an index that objectively indicates the degree of “skin tension and moisture” can be obtained, which is a valuable tool in the development and evaluation of basic cosmetics. obtain. In this case, since the measurement target is a living body, it must be able to measure noninvasively and quickly.

“HEvon Gierke, et al., Physics of Vibrations in
Living Tissues, J. Applied Physiology, 4,886 / 900 (19
The 52) ", to vibrate the vibrator in contact with the skin, to calculate the mechanical impedance from the response, the elastic coefficient mu ₁ of the skin by solving previously derived theoretical formulas of mechanical impedance and viscosity coefficient mu ₂ In this method, a vibrator is excited by a sine wave, the mechanical impedance is measured at a representative finite number of frequencies, and the result is expressed as a simplified mechanical impedance. by solving the theoretical equations obtained by substituting the equation, the aforementioned mu _1, mu ₂ are calculated. Thus, in this method, the measurement of one measurement point is performed a plurality of times, during which the measurement object Since the condition that the physical state of the sample must be stable is required, it cannot be said that the method is suitable for measurement on a living body.

“H.Oka, et al, .Measurement of bio-mechanical pr
oporties using rondom vibration, The Transaction of
the IECE of Japan, E67, 49/50 (1984) "
Japanese Patent Application Laid-Open No. 62-172946 discloses a method and an apparatus for measuring mechanical impedance in a short time by vibrating with vibration having a random frequency distribution.

On the other hand, in clinical medicine, palpation is an indispensable simple diagnostic method. In palpation, the mechanical properties of the living body are detected by pressing or moving with the fingers, and extremely sensitive measurement is possible.However, since it is a measurement method based on experience, qualification and quantification of palpation have been awaited so far. I have been.

[Problems to be solved by the invention]

When measuring the mechanical impedance of a living tissue by the above-described method and apparatus, bones and the like often exist in the lower layer depending on the measurement site, and the vibration is reflected by the bones and the like, and the influence of the structure depends on the measurement. Measurement results tend to be obtained significantly differently than the true values of the living tissue itself. This is a major obstacle to obtaining the mechanical properties of living tissue in a non-invasive manner.

Conversely, it is considered that the mechanical properties including the structural dependence correspond to a sense of hardness when the surface of the living body is pressed with a finger.
Therefore, there is an expectation that an index for objectively evaluating the mechanical properties of the living body surface obtained empirically by palpation may be obtained based on the value of the mechanical impedance measured by the above-described method.

Therefore, a first object of the present invention is to provide a method and an apparatus capable of obtaining true mechanical characteristics of a living tissue by eliminating such a structure-dependent influence.

A second object of the present invention is to provide a method for obtaining an index for objectively evaluating the sense of hardness perceived from the surface of a living body by palpation from a measured value of mechanical impedance including a structure-dependent effect. And to provide a device.

A third object of the present invention is to propose a novel structure of a sensor-incorporated vibrator which serves as an actuator for vibrating a living tissue in the above-described method and apparatus, and also serves as a sensor for detecting a response. is there.

[Means for solving the problem]

The method for measuring the mechanical properties of the surface of a living body according to the present invention, which achieves the first object described above, includes a step of pressing a vibrator against the surface of the living body, and vibrating the vibrator in a predetermined frequency distribution. The driving force and acceleration in the vibrator are measured in the time domain, the driving force and the acceleration measured in the time domain are Fourier-transformed and converted to the frequency domain, and the driving force and the acceleration in the frequency domain are calculated. The frequency characteristic of the mechanical impedance on the surface of the living body is calculated, and the frequency characteristic curve of the mechanical impedance calculated from the theoretical equation of the mechanical impedance using the effective vibration radius a, the elastic coefficient μ ₁ , and the viscosity coefficient μ ₂ as parameters is used as the drive. effective vibration radius a that best approximates the frequency characteristic curve of the mechanical impedance calculated from the force and acceleration, elastic coefficient mu _1, and viscosity coefficient mu ₂ Determine the value, stored in advance correction of the elastic coefficient mu ₁ and viscosity coefficient mu ₂ as a function of the effective vibration coefficients a, by the stored correction factor is determined from the value of the effective vibration radius a which is the determined and it is characterized by comprising the step of correcting the determined value of the modulus mu ₁ or viscosity coefficient mu _2.

The method for measuring the mechanical characteristics of the surface of a living body according to the present invention, which achieves the second object, comprises pressing a vibrator against the surface of the living body, vibrating the vibrator in a predetermined frequency distribution, and The driving force and acceleration in the vibrator are measured in the time domain, the driving force and the acceleration measured in the time domain are Fourier-transformed and converted to the frequency domain, and the driving force and the acceleration in the frequency domain are calculated. Calculate the frequency characteristic of the mechanical impedance on the living body surface, calculate the integral value of the region below the resonance frequency in the frequency characteristic curve of the imaginary part of the calculated mechanical impedance, and use it as the evaluation index of the hardness of the living body surface portion It is characterized by having each step.

FIG. 1 is a block diagram showing the principle of an apparatus for achieving the first object. In the figure, an apparatus for measuring mechanical properties of a living body surface portion of the present invention includes a vibrator 12 pressed against a living body surface 10 and a vibrating means for vibrating the vibrator 12 in a predetermined frequency distribution.
Detecting means 16 for detecting the driving force and acceleration of the vibrator 12 vibrated by the vibrating means 14 pressed against
And Fourier transform means for Fourier transforming the driving force and acceleration in the time domain detected by the detection means 16
18, mechanical impedance calculating means 20 for calculating the frequency characteristic of mechanical impedance on the living body surface 10 from the driving force and acceleration in the frequency domain output by the Fourier transform means 18, an effective vibration radius a, an elastic coefficient μ ₁ , and effective vibration radius a frequency characteristic curve of the mechanical impedance which is calculated the viscosity coefficient mu ₂ from the theoretical equation of the mechanical impedance of the parameters to optimally approximate the frequency characteristic curve of the mechanical impedance calculated from the drive force and acceleration ,
Modulus mu _1, and the curve fitting means 22 to determine the value of viscosity coefficient mu _2, the correction value storing means 24 for storing the correction of the elastic coefficient mu ₁ and viscosity coefficient mu ₂ as a function of the effective vibration radius a The elasticity coefficient μ ₁ or the viscosity coefficient μ determined by the curve fitting means 22 is determined by the correction rate stored in the correction value storage means 24 determined from the value of the effective vibration radius a determined by the curve fitting means 22. _And correction means 26 for correcting the value of ₂ .

FIG. 2 is a block diagram showing the principle of an apparatus for achieving the above-mentioned second object. In the figure, an apparatus for measuring mechanical properties of a living body surface portion of the present invention includes a vibrator 12 pressed against a living body surface 10 and a vibrating means for vibrating the vibrator 12 in a predetermined frequency distribution.
Detecting means 16 for detecting the driving force and acceleration of the vibrator 12 vibrated by the vibrating means 14 pressed against
And Fourier transform means for Fourier transforming the driving force and acceleration in the time domain detected by the detection means 16
18, mechanical impedance calculating means 20 for calculating the frequency characteristic of mechanical impedance on the living body surface 10 from the driving force and acceleration in the frequency domain output by the Fourier transform means 18, and a machine calculated by the mechanical impedance calculating means 20 An evaluation index calculating means 30 for calculating an integral value of a region below the resonance frequency in the frequency characteristic curve of the imaginary part of the impedance to obtain an evaluation index of the hardness of the surface of the living body is provided.

The vibrator structure with a built-in sensor according to the present invention, which achieves the third object, comprises a vibration shaft extending in a direction in which vibration is to be performed, a permanent magnet supported by the vibration shaft via an elastic body, and a permanent magnet. A drive coil opposed to the magnet and held by the vibration axis, an impedance head for outputting two electric signals proportional to the stress and acceleration in the axial direction, and fixed to the vibration axis via the impedance head; And a disc-shaped vibrator.

(Operation)

As will be described in detail in later examples, according to the experimental results of the present inventor, it is determined by curve fitting a frequency characteristic curve based on a theoretical formula of mechanical impedance and a frequency characteristic curve based on measured values. It has been effective vibration radius a, the value of the elastic modulus mu ₁ and the viscosity curve mu _2, both show the change corresponding to the structure-dependent, moreover, a certain function is provided between the effective vibration radius a and the other parameters Is recognized. Therefore, μ ₁ ,
storing correction factor μ _2, μ ₁ is determined from the value of a determined by a curve fit, mu mu ₁ Effect of structural dependency has been removed by correction by the correction factor of _2, mu ₂ value Is obtained.

On the other hand, the frequency of the resonance point in the frequency characteristic curve of the imaginary part of the mechanical impedance calculated from the measured value has a close relationship with the hardness of the measurement target by palpation. Further, a certain relationship is recognized between the frequency of the resonance point and the integral value in a region below the resonance point. Therefore, if an integrated value in a region lower than the resonance point frequency is used as the evaluation index of the hardness by palpation, a stable index can be obtained even if the frequency characteristics are disturbed by noise.

〔Example〕

Configuration of the device The force f (t) acting on a certain point on the surface of the living body and the driving point mechanical impedance when vibrating at a speed v (t) in the direction of the force are Fourier transforms of f (t) and v (t). To F
(F), V (f) Defined by Here, A (f) is a Fourier transform of acceleration a (t) which is a derivative of velocity v (t), and ω is an angular frequency of the vibration to be applied.

FIG. 3 measures f (t) and v (t), calculates the mechanical impedance Z (f) from the Fourier transform based on the equation (1), and further evaluates the mechanical properties of the living body surface. FIG. 3 is a diagram illustrating an example of a hardware configuration of a measurement and calculation device according to the present invention for calculating a parameter.

The random wave generation circuit 144 outputs a sine wave having a random frequency distribution. The output of the random wave generation circuit 144 passes only a frequency component of 30 Hz or more and 1 KHz or less in the low-pass filter 145, is amplified in the power amplifier 146, and is connected to the vibrator 140 of the vibrator 150 with a built-in sensor.
Is applied via

The electric signal is converted into mechanical vibration in the axial direction in the vibrator 140, and the load cell 161 and the impedance head 1 are converted.
The light is transmitted to the vibrator 121 via 60. The load cell 161 is for measuring the static pressure of the vibrator 121 that presses the measurement target 10. A piezoelectric element is incorporated in the impedance head 160, and detects the dynamic pressure and acceleration of the vibrator 121.

The static pressure detected in the load cell 161 is amplified in the strain amplifier 163, and the dynamic pressure and acceleration detected in the impedance head 160 are changed in the charge amplifier 16
The signals are amplified in 6, all are converted into digital signals by the A / D converter 164, and input to the computer 180. The foot switch 165 is for giving instructions to the computer 180 to start and end the measurement.

FIG. 4 is a view for explaining the detailed structure of the sensor-incorporated vibrator 150.

The permanent magnet 141 is supported by the vibration shaft 120 by a leaf spring 142. The pair of drive coils 143 are fixed to the vibration shaft 120 at positions facing the magnetic poles of the permanent magnet 141. When an oscillating current is supplied to the drive coil 143, the electromagnetic force acting between the permanent magnet 141 and the drive coil 143 changes according to the current,
Due to the inertia of the permanent magnet 141, the vibration shaft 120 vibrates in the axial direction. The disc-shaped vibrator 121 is fixed to the vibrating shaft 120 via the load cell 161 and the impedance head 160. With the vibration of the vibrating shaft 120, the load cell 161, the impedance head 160, and the vibrator 121 become a single unit. 120
Vibrates in the axial direction. Reference numeral 162 denotes a connector for connecting a cable to the drive coil 143, a signal cable from the load cell 161 and the impedance head 160.

One of the features of this vibrator with built-in sensor is that it incorporates a load cell for measuring static pressure together with the vibrator and impedance head, and simultaneously measures contact force during measurement. Can be. In addition, the integration improves measurement accuracy, reliability, and operability dramatically. The overall shape is designed to be slender, with a diameter of 20 mm and a length of 110 mm, so that operability in measurement on the skin surface is good.

The sensor-incorporated vibrator 150 is vibrated while being pressed against the surface of the object to be measured with a predetermined static pressure, and its response is detected as dynamic pressure and acceleration by the impedance head 160, and amplified by the charge amplifier 166. A / D converter 16
At 4, it is converted into a digital signal and input to the computer 180. The pressure and acceleration measured in the time domain are converted to the frequency domain according to the fast Fourier transform algorithm, and the frequency characteristic Z (f) of the mechanical impedance is calculated by the equation (1).

Hereinafter, the frequency characteristic Z (f) of the mechanical impedance
Based on the above, the calculation process of the mechanical properties of the biological surface tissue itself excluding the structure-dependent effects and the mechanical properties of the biological surface in a form including the structure-dependent, that is, the biological surface obtained empirically by palpation The calculation process of the index for objectively evaluating the mechanical characteristics will be described.

According to the above-mentioned document by Gierke et al., The theoretical formula of the radiation impedance Z of a sphere oscillating in an infinite homogeneous medium has a sufficiently low frequency of oscillation (for example, 1 KHz or less). It can be assumed that the medium is an incompressible medium when Can be expressed as Here, ρ is the density of the medium, and h ² = ρω ² / (μ
₁ + jωμ ₂ ), μ ₁ is the shear modulus of the medium, and μ ₂ is the shear viscosity of the medium. In this document, a
Is the radius of the vibrating sphere, but as will be described later, the present inventor adopts a different interpretation.

When rationalizing the denominator of equation (2), Is obtained.

T. Yamamoto & H.Oka: “Experimental modeling of b
omechanical impedance characteristics "Med. & Bio
According to l.Eng. & Comput., 24,493 / 498 (1986), the frequency characteristics of mechanical impedance measured on the surface of a living body are classified into three types, soft part characteristics, middle part characteristics, and hard part characteristics, depending on the measurement site. However, since the frequency characteristic of the theoretical solution shown in the equation (3) has the characteristic of the soft part characteristic (the real part monotonically increases), here, only the part showing the characteristic of the soft part characteristic is targeted.

In the present invention, since a vibration is applied only from the surface of a living body, it is considered to be a semi-infinite medium, and a theoretical expression obtained by multiplying Expression (3) by 1/2 is used. Then, based on the interpretation that a is not the radius of the vibrating sphere but the effective radius of the vibrator, the frequency characteristics of the mechanical impedance calculated using a, μ ₁ and μ ₂ as parameters can be obtained by measurement. The values of the parameters a, μ ₁ , and μ ₂ that best fit the frequency characteristic curve of the mechanical impedance are calculated by curve fitting. This method is applied to a model in which only the structure dependency can be arbitrarily changed to correct the correction factors of μ ₁ and μ ₂ as a function of a,
That is, the correction function is determined.

In the measurement for the living body, a, μ ₁ , μ
₂ is calculated, and the correction factors of μ ₁ and μ ₂ determined by the value of a are determined from the correction function, and μ ₁ and μ ₂ are corrected.

A. Experiments on models The experimental results for validating this method and determining the correction function are described below.

(1) Experimental method The viscoelastic coefficient was examined using a material having a tactile sensation similar to that of the skin as a biological simulator. This simulator is a white powder that solidifies in a few minutes when water is added,
It becomes a viscoelastic medium with mechanical properties similar to living tissue. By changing the mixing ratio (weight) of the simulator and water, samples with different densities and viscoelastic coefficients can be made.
This time, sample A (ρ = 1083) and sample B (ρ = 1038.5)
Type.

FIG. 5 is a diagram showing the appearance of a model used in the experiment.

A cylindrical ring 102 made of a plastic film is placed on an iron plate 104, and after adding water and stirring, the sol-like simulator 100 is poured into it. Since moisture evaporates from the surface portion even after solidification, if measurement is started immediately after solidification, a change in mechanical properties during measurement is large. Therefore,
The measurement is carried out at an interval of one hour after the simulator solidification and after the evaporation of water has almost disappeared. The measurement is performed three times for one measurement point, and the average is taken after analysis. The diameter (2a ₀ ) of the vibrator is 5 mmφ and 10 mmφ, and the contact force p is 15 ± 1.
5 and 50 ± 2.5 gf.

(2) Evaluation of Structural Dependence An experiment was performed while changing the thickness of Sample A. The diameter of the plastic film ring was 92 mmφ, the thickness was changed from 50 mm to 4 mm, and the measurement was performed under the conditions of a vibrator size of 5 mmφ and a contact force of 15 ± 1.5 gf. FIG. 6 shows the experimental results. The horizontal axis represents the thickness of the material on a logarithmic scale. In the marks in the figure, ○ indicates the elastic coefficient μ ₁ , △ indicates the viscosity coefficient μ ₂ , and □ indicates the effective vibration radius a. The effective vibration radius here is a parameter obtained from the curve fitting, but is different from the radius a ₀ of the vibrating vibrator, and is substantially the vibration that is vibrated by the vibrator in the medium. Defined as a coefficient proportional to the range. That is, when there is a substance that reflects vibration in the vertical and horizontal directions as compared with a sufficiently large sample, it is considered that the substantial vibration range is reduced and the value of a is reduced.

Μ ₁ , μ ₂ , a is flat from 20mm to 50mm in thickness,
It is considered that there is no influence of the vibration reflection (structure dependence) by the iron plate. However, when the thickness is less than 15 mm, the effect of vibration reflection, that is, the structure dependence is observed, and the apparent mechanical properties seen from the surface change. As the thickness becomes thinner, μ ₁ and μ ₂ both increase, and a tends to decrease. Therefore, μ ₁ , μ obtained from the measurement results
₂ can be considered as the apparent viscoelastic coefficient.

(3) Determination of correction function A strong correlation was found between μ ₁ , μ ₂ , and a from the experimental results, and a correction function for the elastic coefficient μ ₁ and the viscosity coefficient μ ₂ is defined using the effective vibration radius a. .

Flat part of μ ₁ and μ _{2 in} Fig. 6 (thickness 20mm to 50mm)
_Are set to μ _1n and μ _2n , respectively. In FIG. 7A, ○ indicates p (= a / a ₀ , referred to as a correction coefficient) on the horizontal axis, and the correction rate μ on the vertical axis.
₁ / μ _1n is rewritten. Similarly, in FIG. 11B, the horizontal axis represents the correction coefficient p, and the vertical axis represents the correction rate μ ₂ / μ _2n .
Correction functions f ₁ (p) and f ₂ (p) shown below for this result
To The correction curve is determined by obtaining g ₀ , g ₁ , g ₂ , and g ₃ by the least square method. The solid lines in the figure are the approximated correction curves. Correction curve, (the value of p at this time is p _n) fixed to _{f 1 (p) = f 2} (p) = 1 in the case where the thickness is at least 20 mm. It is considered that the measurement points at which the results _satisfying p> pn were not affected by the structure dependence, and the true viscoelastic coefficients μ _1n and μ _{2n of the} medium were obtained. It is not necessary to do it.

The correction function f ₁ (p) for the elasticity coefficient μ ₁ is The correction function f ₂ (p) for the viscosity coefficient μ ₂ is It became. However, this correction function is defined as p < _pn , and when p ≧ _pn , f ₁ (p) = f ₂ (p) = 1.
In this experiment, _pn = 0.745.

(4) When the Medium Constant is Different FIG. 8 shows the result of the same experiment as described above using the sample B having the different medium constant. This sample B was obtained by changing the mixing ratio of water and the simulator (increased the proportion of water). The touch by hand was softer than that of sample A, and μ ₁ ,
μ ₂ of the value is also smaller. Sample A has a thickness of 15
In the case of Sample B, the values of a, μ ₁ and μ ₂ were almost constant when the thickness was 20 mm or more, and the effect of the vibration reflection was reduced when the thickness was 15 mm or less. As a result, apparent viscoelasticity is obtained. For sample A, p _n = 0.745
However, the soft sample B having a small ρ was as large as p _n = 0.866. This indicates that a softer sample (smaller value of mechanical impedance) has a larger effective vibration range.

9A shows the correction coefficient p on the horizontal axis and the vertical axis shows the correction rate μ ₁ / μ _1n. Similarly, in FIG. 9B, the circle on FIG. 9B also shows the correction coefficient p on the horizontal axis and the vertical axis. Μ ₂ / μ _2n . The solid line in each figure is a correction curve obtained by approximating Equation (4) by the method of least squares.

In this case, the correction function f ₁ (p) for the elastic coefficient μ ₁
Is The correction function f ₂ (p) for the viscosity coefficient μ ₂ is And obtained. However, this correction function is p <p _n (= 0.86
6), and when p ≧ _pn , f ₁ (p) = f
₂ (p) = 1.

Correction function obtained from sample A (solid line) to study the change of the correction function when the mechanical characteristics of the sample are different
And the correction function (dotted line) obtained from Sample B are shown in FIGS. 10 (a) and 10 (b). (A) shows the elastic modulus μ ₁ ,
(B) shows the comparison for the viscosity coefficient mu _2.
In both cases (a) and (b), the value of the correction factor of the sample B is larger than the value of the correction factor of the sample A for the same correction coefficient p. This is presumably because sample B is softer than sample A (viscosity is about half as large as sample A) as described above, so that the effective vibration range is large and the sample is easily affected by vibration reflection.

(5) When the measurement conditions are different Using sample A, the size of the vibrator is 10 mmφ and the contact force is 50 ±
The experiment was performed with the thickness changed under the condition of 2.5 gf. The results are shown in FIG. When the thickness is 40 mm or more, a, μ ₁ and μ ₂ are almost constant, but below that, apparent viscoelasticity is obtained due to the influence of vibration reflection.

The circles in FIGS. 12 (a) and 12 (b) show the relationship between the correction coefficient p and the correction rate for each of the elastic coefficient and the viscosity coefficient.
The solid line is the correction curve. In this case, the correction function f ₁ (p) for the elastic coefficient μ ₁ is obtained as follows.

The correction function f ₂ (p) for the viscosity coefficient μ ₂ is It became. However, this correction function is p <p _n (= 0.923)
And when p ≧ _pn , f ₁ (p) = f ₂ (p)
= 1.

FIG. 13 (a) shows how the correction function changes when the measurement conditions of the vibrator contact change.
(B) shows the correction function (dotted line) obtained here and the correction function (solid line) previously obtained under the conditions of the vibrator size of 5 mmφ and the contact force of 15 ± 1.5 gf. (A) for the elastic coefficient μ _1, (b) shows the comparison for the viscosity coefficient mu _2. In both figures, 10mmφ, 50gf for the same correction function p
The correction rate in is increased.

(6) Application of Correction Function Next, using the correction function calculated in this way, an experiment showing the validity of the present method by applying the method of the present invention to a model having non-uniform structural dependence. Will be described.

Copper rod 106 having a length of 120 mm and a diameter of 4 mmφ as shown in FIG. 14
Is a bar model combining 4 pieces, with a thickness of 50mm and a diameter of 150mmφ.
The sample A was buried in the sample A and placed on the iron plate 104 for measurement. An aluminum foot 110 was attached to the bar model and fixed at a position 10 mm deep from the surface of the sample 100. The measurement was performed with a vibrator size of 10 mmφ and a contact force of 50 ± 2.5 gf. As shown in FIG. 15, measurement points were measured twice at each point at 72 points, and the obtained viscoelastic coefficients were averaged.

FIGS. 16 (a) and 16 (b) show the analysis results of the obtained viscoelastic coefficients on a three-dimensional screen. Here, it is referred to as impedance mapping. The overall shape is interpolated by a bi-spline function for the two-dimensional measurement result. FIG (a) the elastic coefficient μ _1, (b) the viscosity coefficient mu ₂
7 is a mapping screen when is set to the Z axis. The shape of the bar model in which the copper rods 106 are assembled in a lattice shape is well represented on the surface. This expresses the shape of a shallow portion viewed from the sample surface. This is because the measured apparent μ ₁ and μ ₂ become larger and the value of “a” becomes smaller than the other measurement points due to the influence of the vibration reflection in the shallow portion. The two ridges extending from the lower left to the upper right are higher than the two ridges extending from the upper left to the lower right, but this is the intersection of the combined copper bars For this reason, as shown in the figure, the two lines extending from the lower left to the upper right are at the top, and the effect of such a slight depth can be expressed. In addition, the lattice point is the highest raised,
This is because, as also shown in FIG. 14, the copper rods are connected at the lattice points by wires 108 in order to fix them in a lattice shape.

For this measurement result, the above-mentioned measurement sample and the same measurement conditions (sample A, vibrator size 10 mmφ, contact force
Apply the correction function obtained at 50 ± 2.5 gf). FIGS. 17 (a) and 17 (b) show the mapping of μ ₁ and μ ₂ after correction. It can be seen that the protruding portion before the correction disappears and is almost flat. Therefore, it was proved that the correction function used here was effective in eliminating the influence of the structure dependence.

B. Measurement of mechanical properties around the eyelid and its analysis (1) Measurement of mechanical properties around the eyelid Using a 4-year-old girl as a subject, the area around the left eyelid shown in FIG.
Measurements were taken at points. The measurement condition is the size of the transducer 5m
mφ and contact force were 15 ± 1.5 gf. This means that to measure at many measurement points in a narrow measurement range such as around the eyelid,
This is because it is necessary to use a small vibrator, but if the vibrator is made smaller, the pressure increases, and the contact force must be reduced. This measurement is one for one site.
Measurements have been performed. FIG. 19 shows the analysis result.
No. 5, No. 6, No. 16 and No. 20 of the measurement site were deleted because the frequency characteristic of the mechanical impedance showed the tendency of the intermediate part characteristic and the method of the present invention was not applied for the above-mentioned reason. ● indicates an elastic coefficient μ ₁ , and △ indicates a viscosity coefficient μ ₂ . μ ₁
And μ ₂ is being almost the same change in such value to the measurement site, there are some unlike that site. It is considered that one of the causes is that only one measurement is performed for one site.

Since it is difficult to understand the correspondence between the measurement points and the parts in the line graph, the analysis results are shown in three-dimensional mapping in FIGS. 20 (a) and (b). (A) is an elastic coefficient μ ₁ mapping screen, and (b) is a viscosity coefficient μ ₂ mapping screen. This screen is a mapping around the left eyelid as shown in FIG. Although this mapping has 45 grid points, the actual measurement result has only 16 data points, so the plane is smoothed with irregular data. Although mu ₁ mapping screen is other figures and symmetrical, this is because of the rotation of the screen to make it easier to observe the irregularities, (a) in the lower left is a lid top, addition of In the figure, the upper left is the upper eyelid.

(2) Application of correction function An attempt is made to apply a correction function to this analysis result. Results of the measurement of ambient eyelids, the smallest value of the modulus mu ₁ 4000
From about 5000 to the true elastic modulus μ _{10 of the} medium itself, which is not dependent on the structure, in the measurement results of Samples A and B.
Are about 1700 and 9500, respectively, but it is difficult to say that they are appropriate, but a correction function obtained from the measurement result of the sample B will be used. FIGS. 21 (a) and 21 (b) show the correction functions f ₁ (p), f
₂ is a mapping screen after μ ₁ and μ ₂ are corrected by (p). The corners of the eyes of μ ₁ and μ ₂ are slightly higher. In addition, the portion that hits the eyelid (lower left in the figure) is swollen, which is considered to be the effect of the eyeball under the eyelid. Since this correction function is based on the structure dependence on an iron plate with extremely large impedance, assuming bones and the like in the living body, if the impedance is not very large like an eyeball, it is considered that the correction is not sufficient. . The purpose of this correction is not to flatten the mapping screen,
The goal is to offset the effects of structure dependence. Therefore, the undulation of the screen obtained after the correction is the original μ of the living tissue.
It is considered that the values are ₁ and μ ₂ , and that point will be further discussed below.

(3) Discussion The lower eyelid, upper eyelid,
The measurement results described so far will be considered separately for the three external corners. Looking at the measurement sites, 1 to 4 are the inner lower eyelids, 8, 9 are the upper eyelids, 10 to 13 are the outer lower eyelids, 14,
Reference numeral 15 denotes the inside external canthus (so-called outer corner of the eye), and reference numerals 18 and 19 denote the outside canthus. Note that the portions 7 and 17 are omitted. Figure 23 is the modulus mu _1, the results of the three sites mentioned above, is (a) before correction, (b) is corrected. The numbers in the circles indicate the measurement site, the solid line indicates the inside, and the dotted line indicates the outside site.

Consider the measurement results before performing the correction. According to the palpation of a finger or the like, the viscoelasticity of the skin itself is dependent on the tissue structure such as bone, so the hardness felt from the surface is different from the hardness of the skin itself. As shown in FIG. 7A, it can be seen that the elastic coefficient increases in the lower eyelid portion from the inside to the outside and further toward the outer eye corner. Similarly, it can be seen that the elastic coefficient increases from the inside to the outside at the outer eye corner. In fact, it feels like this even when palpating the fingers. In addition, among these three parts, it can be seen that the elastic coefficient is the smallest in the upper eyelid part which is felt to be the softest by palpation.

In the experiment, when the obtained elastic modulus is corrected, the elastic modulus of the skin itself is obtained as shown in FIG.
Looking at the lower eyelid, the elastic modulus is opposite to that before correction,
The outside is small and the inside is large. The upper eyelid has the same size as before the correction. It is considered that the elastic coefficient of the skin itself is larger in the inner eye than in the outer eye, that is, the skin is more likely to harden in the outer eye corner as before the correction. This is reasonable considering that skin aging tends to form wrinkles, so-called "crow's feet", on the inner side compared to the outer outer eye corner.

On the other hand, was shown for viscosity coefficient mu ₂ is a Figure 24. As in FIG. 23, (a) is before correction, and (b) is after correction. First, consider before correction. In the lower eyelid,
The inside and outside show a similar tendency along the row of the part numbers, and the viscosity coefficients of 2, 3, 4, and 11, 12 are large. Similarly to the elastic coefficient, the outer side is larger than the inner side. At the outer eye corner, the viscosity is larger on the outside and closer to the eyebrows, and the viscosity coefficient is larger. This is a different tendency from the elastic modulus. The upper eyelid has the smallest viscosity coefficient around the eyelid.

In the viscosity coefficient after the correction in FIG. 9B, the tendency of the lower eyelid is almost the same as before the correction, but the value of the viscosity coefficient is also almost the same. In the upper eyelid portion, there is almost no change before and after the correction. The values are also corrected to be substantially the same in the outer eye corners, but it can be seen that the values increase as the eyebrows are approached. In the corrected elastic coefficient of the skin itself, the inner outer eye corner has a large value, but the viscosity coefficient is opposite, and the inner side is smaller than the outer side.

As described above, it is concluded that the concept of the correction function used in the present invention is effective for measurement / analysis at a site that is affected by structural dependency such as around the eyelid.

Mechanical Properties Including the Effect of Structure Dependence A. Measurement of Biomechanical Impedance and Index of Hardness As described above, the frequency characteristics of the mechanical impedance of the biological surface measured with the device described in FIG. As shown, the characteristics can be roughly classified into three: soft part characteristics (a), intermediate part characteristics (b), and hard part characteristics (c). In the soft part characteristic, the real part becomes a monotonically increasing function as the frequency increases, in the hard part characteristic, the real part becomes a monotonically decreasing function, and in the intermediate part characteristic, the real part becomes a decreasing increasing function. Every characteristic of the imaginary part is an increasing function, but in general, the characteristic of the hard part has no resonance frequency up to 1 KHz. In rare cases, as shown in FIGS. 25 (d) and (e), there are frequency characteristics different from typical patterns.

(1) Index of Hardness FIG. 26 shows the frequency characteristic of mechanical impedance showing the soft part characteristic. The imaginary part (reactance) starts from negative and increases with frequency, becomes 0 at the resonance frequency, and further increases. However, measurement on the surface of a living body includes an error due to involuntary movement of the living body and the like.
The moving average of the points was smoothed three times. The solid line in the figure indicates the frequency characteristics before the moving average is applied, and the broken line indicates the frequency characteristics after the application. FIG. 27 shows the frequency characteristics of the soft part characteristic (solid line), the intermediate part characteristic (dashed line), and the hard part characteristic (dashed line) of the back of the hand.
From this figure, it can be seen that the harder the target, the higher the resonance frequency, and the lower the frequency, the higher the absolute value of the reactance. Therefore, the harder the object
The area of the shaded area in Fig. 26 increases. It has been found from the previous analysis that the reactance in the low frequency range strongly reflects the elasticity of the DUT and also reflects the viscosity. Therefore, this area is defined as the hardness index SI (Stiffness Index) as viewed from the surface of the living body as follows.

Here, f ₀ is the resonance frequency, and the reason why the integration range is set to be from 40 Hz is because of the limitation by the frequency range that can be measured by the measurement sensor. The index SI is dimensionally [N / m],
It is thought that it expresses elasticity including viscosity and inertia.
Further, in the hard part characteristics, since the resonance frequency is generally not up to 1 KHz, the area is determined assuming that the resonance frequency is 1 KHz. According to this method, an average and stable result can be obtained even if the frequency characteristics are somewhat poor. Even in the case of frequency characteristics different from typical patterns as shown in FIGS. 25 (d) and (e), a sufficient result can be obtained.

The reason for not using the real part of the impedance when calculating the index is that when comparing the soft part characteristic and the intermediate part characteristic, the real part of the intermediate part characteristic may be smaller than that of the soft part characteristic in the low frequency range, This is because it does not match the sense of hardness. It is also conceivable to use the absolute value of the mechanical impedance as an index of hardness, but this is not so good. Furthermore, although the same resonance frequency can be obtained depending on the part, the reactance in the low frequency range may be significantly different, so care must be taken when using the resonance frequency as an index of hardness. Therefore, the present inventor newly proposes that the area up to the resonance frequency of the reactance is used as an index of hardness.

(2) Mechanical Impedance and Hardness Index When lightly touching the surface of a living body with a finger, there are parts where the hardness feels different (for example, a part with a bone on the back of the hand and a part without the bone). This is because the stiffness is felt in the form including the hardness of the tissue structure under the surface of the living body, that is, bone, etc., and the hardness itself of the skin on the living body surface is not different. Here, this is called apparent hardness. The present inventor has been studying the structural dependence of the mechanical properties so far, and the relationship between the structural dependence of the mechanical impedance and the hardness index will be described.

FIG. 28 shows frequency characteristics when the model described in FIG. 5 is measured under conditions of a transducer diameter of 5 mm and a contact force of 15 gf (measurement condition A). The solid line in the figure indicates that the simulator thickness is 50 mm, the broken line is 7 mm, and the dashed line is 4 mm. It can be seen that the absolute value of the reactance increases in the low frequency range as the thickness decreases.
In the real part, a change from the soft part characteristic to the intermediate part characteristic is observed in a low frequency range. FIG. 29 shows the relationship between the thickness of the simulator and the apparent hardness SI. In the figure, Δ is the condition A,
○ is the result under condition B (vibrator diameter 10 mm, contact force 50 gf). The smaller the thickness of the simulator is, the higher the apparent hardness is, because it is gradually affected by the structure dependence of the iron plate. However, even if the thickness is the same, the SI is different if the measurement conditions (vibrator diameter or contact force) are different. This is because the frequency characteristics of the impedance itself vary depending on the measurement conditions. For example, it is the same as feeling that the hardness is different when the finger is lightly pressed against the skin and when the skin is pressed hard. Therefore,
Although it is possible to compare SIs under the same measurement conditions, it is difficult to compare SIs under different measurement conditions.
In the same figure, the SI is almost constant from about 20 mm or more under the condition B and from about 15 mm or more under the condition A. Will no longer be affected. In other words, it can be said that the SI shown at a thickness that does not depend on the structure is the hardness of the simulator itself.

It has been described that when the thickness of the simulator is reduced, the apparent hardness is also increased, but when the hardness of the simulator itself is increased, the apparent hardness is naturally increased. Furthermore, if the hardness of the iron plate under the simulator changes, the apparent hardness from the surface also changes. In this measurement method, the mechanical impedance is measured by exciting the simulator from the surface, but when the thickness is reduced, the mechanical impedance obtained by vibration reflection from the underlying structure changes.
That is, the magnitude of the mechanical impedance of the simulator and the lower structure influences, and the reflection is more likely to occur when the structure is harder, that is, when the mechanical impedance of the structure is larger. Therefore, as the hardness of the structure becomes harder, the influence of reflection becomes stronger, and it is considered that the apparent hardness also becomes harder.

B. Mapping of hardness by mechanical impedance In the simulator described above, copper rods combined in a grid pattern as shown in Fig. 14 were embedded (called a bar model), and iron M blocks were embedded Experiments were performed on two cases (called block models). The measurement was performed twice for one measurement point, the transducer diameter was 10 mm, and the contact force was 50 gf, and the above-mentioned SI was obtained. In addition, the measurement result was represented by a three-dimensional image (referred to as SI mapping) using bicubic spline interpolation so that the distribution of hardness can be grasped visually and intuitively.

(1) Bar model Four 120 mm long, 4 mm diameter copper rods are combined and embedded in the simulator (50 mm thick, 150 mm diameter) as shown in Fig. 8 (a) and placed at a position 10mm from the surface. A bar model was prepared by fixing, and an experiment was performed. Since the bar model is symmetric, only one side is measured, as shown in FIG.
The evaluation was performed at 72 (12 × 6) points. FIG. 30 shows the SI mapping of hardness. In this figure, a state in which copper rods are combined in a lattice shape is well represented. The two ridges that extend from the lower left to the upper right are higher than the two ridges that extend from the lower right to the upper left, but this is the upper side of the combined copper bar. , The difference on the down side. Also,
The part where the copper bars cross is higher than the others,
This is due to the wires used to fix the copper rods in a grid, as also shown in FIG.

(2) Block model An M block with a height of 55 mm is embedded in the simulator (thickness: 65 mm, diameter: 200 mm) as shown in Fig. 31 so that the highest part of the block is 10 mm from the surface. A block model was created and experiments were performed. FIG. 32 shows the measurement points, but only half are shown in the figure, and actually 105 points were measured. Fig. 33 shows the SI mapping of hardness. In the figure, two ridges appear. This corresponds to the peak of the block, and the valley of the block is well represented. It is considered that the four corners of the SI mapping are large because the size of the simulator was not sufficient compared to the size of the vibrator, and thus the influence of the film side wall was given.

C. SI mapping of biomechanical impedance In order to confirm that the proposed hardness index can be applied to the surface of a living body, measurements were made on the back and chest of the hand. These sites are affected by bones under the surface of the living body and the like, and the hardness indicated by the SI mapping is the apparent hardness.

(1) The back of the hand In the back of the hand, the structure of the lower part of the skin is complicated and the skin is thin, so the oscillator diameter is 5 mm and the contact force is 15 gf. The measurement was performed twice. Fig. 34 shows the measurement points on the back of the left hand (8 x 5: above the grid points)
Indicates 40 points. Fig. 35 shows the lattice of the skeleton viewed from the back of the hand (Kaneko: Japanese Body Anatomy 1 (Bone, Ligament, Myology)
71 (Ryozan-do), Fig. 36 shows SI mapping. It can be seen that it becomes the hardest on the metacarpophalangeal joint, and the difference in hardness between the region with and without the metacarpal finger clearly appears.
Also, since the SI on the carpal bone is small even on the metacarpal bone, if the viscoelasticity of the skin surface is the same, there is little effect on the structure such as bone, that is, the skin is smaller than the metacarpal side. It is considered thick.

(2) Chest Since the chest has a large chest wall area and a relatively simple structure compared to the back of the hand, the measurement was performed twice with the subject lying on his / her back with the vibrator diameter being 10 mm and the contact force being 50 gf.
Since the measurement on the left chest cannot be performed accurately due to the influence of the heartbeat, 105 points (15 × 7:
(On a grid point). Fig. 38 shows the skeleton of the chest (same as above).
FIG. 39 shows SI mapping. The apparent hardness is higher on the collarbone and from the sternum to the sternum, and the difference between the part with ribs and the part without ribs is well expressed. In the mapping, since the SI on the clavicle and the sternum were extremely large, the height was expressed in logarithm.

D. Hardness index and palpation (1) Experimental method and results Vibrator diameter 10 mm, contact force 50
The measurement was performed twice per point, and the average value of SI was obtained. As shown in FIG. 40, the measurement site was an area of 8 cm × 16 cm extending over the tibialis anterior muscle, the peroneal muscle, and the triceps surae outside the lower leg, and the measurement points were 40 points every 2 cm. Since the measurement site is on the outer side of the lower leg, the function of the muscles is considered to vary depending on slight changes in the ankle joint, and it is considered that the muscle tone changes. Therefore, the ankle joint was fixed by taping at a substantially right angle. In parallel with the mechanical impedance measurement, first the acupuncturist and then the masseur palpate the entire body and 5 points per point.
A map expressing the hardness by points of grade (the degree of hardness is substantially equal) was prepared. Next, the mechanical impedance was measured at 20 points on the tibia side, and a map of the hardness index was prepared by the method described below. Further, the acupuncturist and masseur performed palpation, created a map for the second palpation, and then measured the mechanical impedance of the remaining 20 points on the ankle side. Once again, the acupuncturist and masseur performed the third palpation,
A map was created. The reason why the palpation was performed three times was to take into account the change in the degree of muscle tone due to the change in the ankle joint angle during the measurement because the entire measurement took about 2 hours. For the same reason, the measurement of the mechanical impedance was also performed twice.

FIG. 41 and FIG. 42 show mapping of the lower leg of a 24-year-old man by performing palpation and mechanical impedance measurement. Acupuncturists report that the lower leg muscles of the subjects are generally thin, making it difficult to distinguish the three muscles. The pressure during palpation is about 100-500 g. At the start of the measurement, the ankle joint moved slightly, and the results of palpation differed between the acupuncturist and the masseur. Also, the angle of the ankle joint at the end of the measurement is considerably different from that at the start, and it is considered that the angle gradually changed during the measurement. The subject also complained of paralysis (numbness) of the ankle joint in the second half of the measurement. Therefore, the mapping of the palpation was performed for the 20 points on the tibia side (first half) of the first masseur (Palpation of the acupuncturist was excluded because the angle of the ankle joint is different.) 2
The average value was obtained from the palpation results of the second acupuncturist and masseur, and the result was set to 20 points. For the 20 points on the ankle side (the latter half), the average value of the palpation results of the second acupuncturist, the masseur, the third acupuncturist, and the masseur was obtained and mapped as the values of the remaining 20 points.

Comparing the palpation in FIG. 41 and FIG. 42 with the SI mapping, it can be seen that both become harder toward the tibialis anterior and the ankle. However, in SI there are some peaks on the tibialis muscle: the palpation is less clear,
It is shown that there is a considerably hard part in the central part of the tibialis anterior muscle. SI seems to be able to distinguish the features of the three muscles, but palpation makes it hard to tell. In the present results, the ankle joint angle changed during the measurement, and it was also a result of one case, so a clear comparison could not be obtained by comparing the fine parts, but the overall tendency (tibialis anterior muscle and (Stiffer towards the ankle) can be considered consistent. Palpation and SI as shown in Fig. 43
Has a strong correlation of 0.797, so S
I consider that I is sufficient as a hardness index corresponding to palpation.

〔The invention's effect〕

As described above, according to the present invention, it is possible to measure the mechanical properties of the living body surface tissue itself without the influence of the structure dependency inside the living body, and on the other hand, experience the palpation in a form including the structure dependency. It is possible to obtain an index for objectively evaluating the mechanical properties of the living body surface that can be obtained objectively.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle configuration of a first device according to the present invention, FIG. 2 is a diagram showing the principle configuration of a second device according to the present invention, and FIG. 3 shows an embodiment of a measuring device according to the present invention. FIG. 4, FIG. 4 is a detailed view of a sensor-incorporated excitation base according to the present invention, FIG. 5 is a view showing the appearance of a model used in the experiment, FIG. 6 is an elastic coefficient μ ₁ and a viscosity coefficient μ of the model. ₂ and a diagram showing the relationship between the calculation result of the effective vibration radius a and the thickness d of the model. FIG. 7 is a diagram showing the relationship between μ ₁ and μ ₂ and the correction coefficient p. FIG. 8 is a diagram showing the relationship between different medium constants. 6, FIG. 9 is a diagram similar to FIG. 7 with different medium constants, FIG. 10 is a diagram showing a comparison of correction functions with different medium constants, and FIG. FIG. 12 is a view similar to FIG. 7 under different measurement conditions, and FIG. 13 is a view similar to FIG. FIG. 14 shows a comparison of correction functions under constant conditions, FIG. 14 shows an appearance of a bar model, FIG. 15 shows a measurement point of the bar model, and FIG. 16 shows μ ₁ and μ before correction in the bar model. Figure representing _two mappings, Fig. 17 Figure representing a mu _1, mu ₂ mapping corrected in bar model, FIG. 18 represents the interpolation point and the measuring points around eyelids figure 19 figure eyelid ambient diagram showing the measurement results, Fig. FIG. 20 representing a mu _1, mu ₂ mapping of the eyelid around before correction, Figure 21 Figure representing a mu _1, mu ₂ mapping eyelid around the corrected first 22 illustration view showing the upper eyelid around eyelids, lower eyelid, the lateral canthus portion, FIG. 23 FIG. representing the different parts of mu ₁ before and after the correction, Figure 24 Figure representing the different parts of the mu ₂ before and after correction , Fig. 25 shows the frequency characteristics of some characteristic biomechanical impedances, Fig. 26 shows the hardness FIG. 27 is a diagram showing an evaluation method, FIG. 27 is a diagram showing a change in a resonance frequency according to the hardness of a living body, FIG. 28 is a diagram showing a change in a frequency characteristic according to a thickness of a model, and FIG. 29 is a diagram of the model. FIG. 30 is a diagram showing a relationship between thickness and SI, FIG. 30 is a diagram showing mapping of SI values in a bar model, FIG. 31 is a diagram showing an M block model, FIG. 32 is a diagram showing measurement points in an M block model, FIG. 33 is a diagram showing the mapping of SI values in the M block model, FIG. 34 is a diagram showing measurement points of the back of the hand, FIG. 35 is a skeleton diagram viewed from the back of the hand, and FIG. 36 is a diagram of the SI value of the back of the hand. Fig. 37 shows the mapping, Fig. 37 shows the measurement points of the chest, Fig. 38 shows the skeleton of the chest, Fig. 39 shows the mapping of SI values of the chest, Fig. 40 shows the measurement of the right lower leg lateral part FIG. 41 is a diagram showing the points. FIG. 42 is a diagram showing SI mapping of the outer side of the right lower leg, FIG. 43 is a diagram showing correlation between the result of palpation and SI mapping, and in the figure, 10: biological surface, 12, 121: vibration 140, a shaker, 150, a built-in sensor shaker, 160, an impedance head, 161, a load cell, 162, a connector.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-107224 (JP, A) JP-A-61-193647 (JP, A) JP-A-59-120130 (JP, A) JP-A-2-107224 279135 (JP, A) JP-A-60-85729 (JP, A) JP-A-59-168835 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) A61B 5/00 G01N 29 / 16

Claims (5)

(57) [Claims] 1. A vibrator (12) is pressed against a living body surface (10),
The vibrator (12) is vibrated in a predetermined frequency distribution, the driving force and the acceleration of the pressed and vibrated vibrator (12) are measured in a time domain, and the driving force measured in the time domain is measured. And acceleration are converted into a frequency domain by Fourier transform, and frequency characteristics of mechanical impedance on the living body surface are calculated from the driving force and the acceleration in the frequency domain, and the effective vibration radius a, the elastic coefficient μ ₁ , and the viscosity coefficient The effective vibration radius a and the elastic coefficient that the frequency characteristic curve of the mechanical impedance calculated from the theoretical equation of the mechanical impedance with μ ₂ as a parameter optimally approximates the frequency characteristic curve of the mechanical impedance calculated from the driving force and the acceleration. μ
₁ and the value of the viscosity coefficient μ ₂ are determined. The correction factors of the elastic coefficient μ ₁ and the viscosity coefficient μ ₂ as a function of the effective vibration radius a are stored in advance, and are determined from the determined value of the effective vibration radius a. by the stored correction factor is, the measuring method of the mechanical properties of the biological surface portion, characterized by comprising the step of correcting the determined value of the modulus mu ₁ or viscosity coefficient mu _2. 2. A vibrator (12) is pressed against a living body surface (10),
The vibrator (12) is vibrated in a predetermined frequency distribution, the driving force and the acceleration of the pressed and vibrated vibrator (12) are measured in a time domain, and the driving force measured in the time domain is measured. And acceleration are converted to a frequency domain by Fourier transform, and a frequency characteristic of mechanical impedance on the living body surface is calculated from the driving force and acceleration in the frequency domain, and a frequency characteristic curve of an imaginary part of the calculated mechanical impedance. A step of calculating an integral value of a region below the resonance frequency in (1) and using the integrated value as an evaluation index of hardness of the living body surface portion. 3. A vibrator (12) pressed against a living body surface (10).
A vibrating means (14) for vibrating the vibrator (12) in a predetermined frequency distribution; and a driving force and acceleration in the vibrator (12) pressed and vibrated by the vibrating means (14). (16), a Fourier transform means (18) for performing a Fourier transform of the driving force and the acceleration in the time domain detected by the detect means (16), and an output of the Fourier transform means (18) A mechanical impedance calculating means (20) for calculating a frequency characteristic of a mechanical impedance at the living body surface (10) from a driving force and an acceleration in a frequency region to be applied; and an effective vibration radius a, an elastic coefficient μ ₁ , and a viscosity coefficient μ ₂ . The frequency characteristic curve of the mechanical impedance calculated from the theoretical equation of the mechanical impedance as a parameter is optimized based on the frequency characteristic curve of the mechanical impedance calculated from the driving force and the acceleration. Effective vibration radius a of similar elastic modulus μ
_1, and the correction value storing means for storing the curve fitting means for determining a value of the viscosity coefficient μ ₂ (22), the correction of the elastic coefficient mu ₁ and viscosity coefficient mu ₂ as a function of the effective vibration radius a (24) And the effective vibration radius a determined by the curve fitting means (22).
The stored correction factor to be determined from the values the correction value storing means (24), correction means (26 to correct the value of the correction coefficient mu ₁ or viscosity coefficient mu ₂ determined by curve adaptation means (22) ). A device for measuring mechanical properties of a surface of a living body, characterized by comprising: 4. A vibrator (12) pressed against a living body surface (10).
A vibrating means (14) for vibrating the vibrator (12) in a predetermined frequency distribution; and a driving force and acceleration in the vibrator (12) pressed and vibrated by the vibrating means (14). (16), a Fourier transform means (18) for performing a Fourier transform of the driving force and the acceleration in the time domain detected by the detect means (16), and an output of the Fourier transform means (18) Mechanical impedance calculating means (20) for calculating the frequency characteristic of mechanical impedance on the living body surface (10) from the driving force and acceleration in the frequency region to be changed, and the imaginary part of the mechanical impedance calculated by the mechanical impedance calculating means (20) An index value calculating means (30) for calculating an integral value of a region below the resonance frequency in the frequency characteristic curve of the index and calculating the index as an index for evaluating the hardness of the surface of the living body. Apparatus for measuring mechanical properties of parts. 5. A vibrator with a built-in sensor used in the method according to claim 1 or 2, wherein the vibrating shaft extends in a direction to vibrate, and the vibrating shaft extends through an elastic body. A permanent magnet (141) supported by the (120), a drive coil (143) opposed to the magnetic pole of the permanent magnet (141), and held by the vibrating shaft (120); An impedance head (160) for outputting two electric signals proportional to the acceleration, and a vibration axis (12) through the impedance head (160).
And (b) a disk-shaped vibrator (121) fixed to the sensor.