JPH027428B2 - - Google Patents

Abstract

PURPOSE:To make it possible to measure the mechanical properties of biological substances such as skin and hair continuously as well as highly accurately over a long period of time through elimination of the mechanical fatigue of a sample by slackening the sample while the measurement is suspended. CONSTITUTION:A sample 1 coated with a cosmetic is clamped between clamps 2 and 3. Then, a servomotor 24 is rotated in forward direction so that the sample 1 is pulled by an initial strain amount through gears 23, 22, a bolt 19, a crosshead 18 and a force detector 5. At the same time, the sample 1 is reciprocatively vibrated by means of an electrically-operated vibrator 4. During the time of this measurement, the output of the force detector 5, together with the output of a displacement detector 11, is fed to a complex elastic modulus calculating circuit. When the measuring time has passed and the suspension time starts, the servomotor 24 is driven in the backward direction to slacken the sample 1 thereby to allow the sample 1 to recover from its fatigue. Then, the same operations are alternately repeated. Thereby, it is possible to replace the abstract expression of pliability of the skin coated with a cosmetic by a mechanical value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the mechanical properties (complex The present invention relates to a method for measuring the mechanical properties of biological materials such as skin and hair, which enables continuous and highly accurate measurement of the elastic modulus for a long period of time.

Generally, as a method to investigate the mechanical properties of materials that are prone to mechanical fatigue, such as animal skin (stratum corneum), the conventional method is to perform a tensile test and evaluate it from the breaking strength, breaking strain, Young's modulus, etc. was.

However, this method has the disadvantage that it is not possible to perform continuous measurements on a single sample because the sample is broken.

Another method for investigating mechanical properties is to apply a certain kind of strain to the sample and continuously examine its complex modulus, but even with this method, it is difficult to detect mechanical properties such as the skin (stratum corneum). Weak materials are prone to mechanical fatigue when stretched, and the complex modulus of elasticity decreases over time during measurement, making long-term evaluation of mechanical properties impossible. The present invention has been made in view of these points, and the contents thereof will be explained below based on the illustrated embodiments.

1 is a sample made of human skin (stratum corneum), which is composed of a collection of scale-like keratin bodies 2A as shown in Fig. 2, and the thickness H of the scale-like keratin bodies 2A.
are laminated in about 10 to 20 layers with a thickness of about 1 to 2μ.

Further, the length I is approximately 30 to 40μ.

Clamps 2 and 3 are designed to hold the sample 1. Clamp 2 is connected to an electric vibrator 4 and applies sinusoidal reciprocating vibration to the sample 1 in the direction of arrow A or B.

Further, the clamp 3 is connected to an initial strain imparting device 6 via a known force detector 5, and is configured to pull the sample 1 by Δl in the direction of arrow C. That is, Δl is the initial strain amount, and l is the length of the sample 1, which indicates the effective length between the tips of the clamps 2 and 3. This initial strain applying device 6 applies a tensile force to the sample 1 only during measurement of the sample 1, and actively applies slack to the sample 1 while the measurement is stopped. It is not intended to reduce fatigue, but rather actively provides recovery power.

The idea of giving slack to the sample 1 during this measurement stop is the key point of the present invention.

The electric vibrator 4 described above mainly uses a movable iron core 7.
It is composed of a vibration shaft 8 having a vibration shaft 8, a disc-shaped leaf spring 9 provided on both sides of the vibration shaft 8, and an electromagnetic coil 10 disposed around the movable iron core 7.
By passing a sinusoidal current through the movable iron core 7, the movable iron core 7 reciprocates in the axial direction, so that the vibration shaft 8 integrally formed with the movable iron core 7 reciprocates in the directions of arrows A and B.

The plate spring 9 described above is integrally formed with the vibration shaft 8, so that it reciprocates in the axial direction. 11 is the vibration axis 8
A displacement detector connected to the other end 12 has a function of detecting the displacement of the sample 1 via the sensing lever 13 and the strain gauge 14. Reference numeral 15 denotes an amplifier for amplifying the displacement output from the displacement detector 11, and the amplified displacement output signal is input to the complex modulus calculation circuit 16. 17 is force detector 5
The force output signal amplified by the amplifier for amplifying the force output signal from the oscillator is inputted to the complex modulus calculation circuit 16. The above-mentioned initial strain applying device 6 mainly includes a crosshead 18, a screw rod 19 for moving the crosshead 18 in the direction of arrow C or D, a guide rod 20, a slide ball bearing 21, and a screw rod for rotating the screw rod 19. A gear 22 directly connected to the screw rod 19, a gear 23 meshed with the gear 22, a servo motor 24, a gear 25 meshed with the gear 22, and a potentiometer as a detector for detecting the length by which the sample 1 is stretched. It consists of 26 yometers.

Thus, when the servo motor 24 rotates in the declination angle, the screw rod 19 rotates via the gears 23 and 22.
The crosshead 18 is moved in the direction of arrow C or the direction of arrow D, and the clamp 3 is moved in the same direction together with the force detector 5 integrally attached to the crosshead 18 to apply a tensile force (force in the positive direction) to the sample 1. to give initial strain, or to give slack (force in the negative direction). 27 is an initial strain amount setting circuit connected to the servo motor 24;
The rotational speed of the servo motor 24 is controlled by commanding a signal to ultimately set the initial strain amount Δl. 28 is a measurement time setting circuit, as shown in Figure 5, the measurement time t is 20 seconds and the stop time T.
For example, the configuration is such that the measurement can be repeated continuously for 10 minutes, and during the measurement time t, a signal is given to operate the electric exciter 4 for that time and the initial strain amount setting circuit 28 is For this, a signal is applied to maintain the initial strain amount Δl.

On the other hand, during the stop time T, the electric vibrator 4 is inactivated and the initial strain amount Δl is set to zero, and a signal is sent to the initial strain amount setting circuit 28 to give the sample 1 a slack ΔQ. I am doing this to express my feelings.
Reference numeral 29 denotes an oscillation circuit which is activated by a signal from the measurement time setting circuit 28 and operates the electric exciter 4 via a power amplifier 30.

Reference numeral 31 denotes an X-Y2 pen recorder, which is designed to record the measurement calculation results calculated by the complex modulus calculation circuit.

32 is an interface, and 33 is a digital printer, which is designed to digitally display the measurement calculation results calculated by the complex modulus calculation circuit.

The measurement time setting circuit 28 described above sets the measurement time t.
The stop time T can be changed as appropriate, such as 20 seconds or 30 seconds, and the stop time T can be changed as appropriate in minutes from 2 minutes to 99 minutes.

Next, the operation mode of the device of the present invention having the above configuration will be explained.

One example of a sample coated with cosmetics: length 20mm, width 5
20 μm thick with tweezers etc. and hold it between clamps 2 and 3.

Thereafter, by setting the initial strain amount setting circuit 27 to a positive operating state, the servo motor 24
gear 23 and gear 2.
2, screw rod 19, crosshead 18, force detector 5,
The sample 1 is pulled in the direction of arrow C via the clamp 3 by an initial strain amount Δl.

On the other hand, due to the simultaneous operation state of the measurement time setting circuit 28 and the initial strain amount setting circuit 27, a sine wave current flows through the oscillation circuit 29 and the power amplifier 30 to the electromagnetic coil 10 that constitutes the electric exciter 4. Therefore, the sample 1 is caused to reciprocate in the direction of arrow A or B via the movable iron core 7, vibration shaft 8, and clamp 2.

That is, while the initial strain is applied to the sample 1, the sample 1 is stretched or contracted in the longitudinal direction. In other words, during the measurement of the mechanical properties of the sample 1, the sample 1 is vibrated back and forth while an initial strain amount Δl is applied to the sample 1. As mentioned above, this measurement time t is 20 or 30 seconds.

During this measurement time t, the output signal P from the force detector 5 is amplified by the amplifier 17 and input to the complex modulus calculation circuit 16.

On the other hand, the output signal Q from the displacement detector 11 is amplified by the amplifier 15 and is then amplified by the complex modulus calculation circuit 16.
Here, the output signal P and the output signal Q are calculated, and the sample elastic modulus is displayed by the X-Y2 pen recorder 31 and digital printer 33.

When the measurement time t has elapsed and the stop time T begins, the initial strain amount setting circuit 27 is brought into a negative operating state, and the servo motor 24 is rotated in the negative direction.
The gear 23, the gear 22, and the screw rod 19 are rotated in the opposite direction,
The crosshead 18, force detector 5, and clamp 3 are moved in the direction of arrow D to give slack to the sample 1 and to recover the fatigue of the sample 1.

Thereafter, similar operations will be repeated alternately and continuously.

Next, graph A shown in FIG. 6 is the result of an actual experiment using the apparatus of the present invention, and shows the change in the elastic modulus of human skin after applying the cosmetic.

Human skin (stratum corneum) was used as a sample, and a softening lotion (S company, Skin l ₀ ) was applied as a cosmetic.Temperature: 25°C, relative humidity: 50% The meaning of this experimental data is as follows.

Generally, when a cosmetic is applied to the skin (stratum corneum), its softening effect increases its "suppleness" over time, and it exhibits a certain form of mechanical behavior, but when measured over a long period of time, Due to its softening effect, mechanical fatigue of the sample, that is, the skin, becomes large, and the elastic modulus only decreases and does not recover. Therefore, long-term measurements could not be carried out.

In contrast, according to the present invention, by giving sample 1 slack while the measurement is stopped, its mechanical behavior is consistent with theory or experience even when measured for a long time. It became possible to replace the abstract expression of "flexibility" with mechanical values.

Therefore, the present invention has the above-mentioned structure and function, and in particular, applies an initial strain in the tensile direction to the sample only when measuring the complex modulus of elasticity.
This was done to eliminate mechanical fatigue of the sample by relaxing the sample while the measurement was stopped, which has the effect of allowing intermittent measurement cycles to be repeated over a long period of time to obtain highly accurate measurement results. .

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of the present invention, in which a shows a state in which the sample is held between clamps, b shows a state in which an initial strain is applied to the sample in the tensile direction, and c shows a state in which the sample is held at the time of stopping the measurement test. This shows a state in which slack is given to the Figure 2 shows human skin (stratum corneum) as a sample.
3 is a schematic plan view of the device of the present invention, and FIG. 4 is a schematic front view of the device of the present invention, shown together with a block diagram. Figure 5 shows a so-called test in which initial strain is applied to the sample and vibration is applied in the reciprocating direction.
This shows a state in which the measurement time t and the stop time T during which the vibration is stopped, the initial strain is released, and the sample is given slack are alternately connected and repeated. Figure 6 is a graph showing experimental data obtained using the apparatus of the present invention. Graph A shows the case where the sample was coated with cosmetics, and graph B shows the case where the sample was raw without any cosmetics applied. , time is shown on the horizontal axis and elastic modulus is shown on the vertical axis. 1... Sample, 2, 3... Clamp, 4... Electric vibrator, 5... Force detector, 6... Initial strain imparting device, 1
1...Displacement detector, 16...Complex elastic modulus calculation circuit, 2
7... Initial strain amount setting circuit, △l... Initial strain amount, l... Effective length of sample.

Claims (1)

[Claims] 1. An initial strain amount Δl in the tensile direction is applied to the sample 1 only during the measurement time t, and reciprocating vibration in the horizontal direction is applied to the sample 1, while during the stop time T, the sample 1 is The applied initial strain amount △l is released to give a slack △Q, and the measurement time t and stop time T are alternately and continuously repeated to the sample 1 and the change mode of its elastic modulus is measured. A method for measuring the mechanical properties of biological materials such as skin and hair that have characteristics. 2. A method for measuring the mechanical properties of biological materials such as skin and hair in which cosmetics are applied to sample 1, as set forth in claim 1. 3. An initial strain imparting device 6 that moves together with the force detector 5 for imparting an initial strain Δl in the tensile direction to the sample 1, and a vibration shaft 8 for imparting reciprocating vibration in the horizontal direction to the sample 1. electric exciter 4 having
, a displacement detector 11 connected to the vibration shaft 8, and a measurement time setting circuit 28 that sends operation signals to the initial strain imparting device 6 and the electric exciter 4 during the measurement time t.
and the initial strain amount △ of the sample 1 during the stop time T
an initial strain amount setting circuit 2 which applies a signal to the initial strain amount imparting device 6 to cancel l and give a slack ΔQ;
7, and a complex elastic modulus calculation circuit 16 configured to take in and calculate output signals from the displacement detector 11 connected to the force detector 5 and the vibration shaft 8. Mechanical properties of biological materials such as skin and hair measuring device.