JP2023089194A - Biological sensor - Google Patents

Abstract

To provide a biological sensor which is capable of detecting a motion of each muscle and is easy to attach and constitute.SOLUTION: A biological sensor (100), in use, is mounted on a living body as a subject. The biological sensor includes: a light emitting unit (11) for irradiating a living body with light; a light receiving unit (12) for receiving return light from a muscle of at least a part of the living body; and an output unit (13) for outputting information on the deformation of the muscle of the part on the basis of a detection signal from the light receiving unit corresponding to the received return light.SELECTED DRAWING: Figure 1

Description

The present invention relates to biosensors, and more particularly to the technical field of biosensors that measure the state of a living body using optical technology.

As this type of device, for example, there is a device that exerts exerted muscle strength corresponding to the minimum value of blood oxygen saturation in the muscles of the subject estimated from a correlation table showing the correlation between oxygen saturation and exerted muscle strength. proposed (see Patent Document 1).

Alternatively, there has been proposed a device that is fixed to the subject's arm by a wearing band, has a pressing member that changes according to the contraction state of the muscles, and outputs a detection signal corresponding to the movement displacement of the pressing member. (see Patent Document 2).

JP-A-2001-70289 JP-A-5-068675

The technique described in Patent Document 1 monitors the oxygen saturation that decreases (that is, changes appear) due to muscle contraction for a certain period of time, so there is a technical problem that instantaneous muscle contraction cannot be detected. there is a point In the technique described in Patent Document 2, since the wearing band is wrapped around the subject's arm, for example, the contraction that combines the movement of the agonist muscle and the movement of the antagonist muscle is detected, and the contraction of each muscle can be detected. There is a technical problem that it is not possible.

In addition, electromyography, which measures the potential of the body surface, requires time and care to install the sensor, and in addition, there are technical problems in that a highly accurate detection circuit is required to detect the weak potential. There is

SUMMARY OF THE INVENTION It is an object of the present invention to provide a biosensor that can detect movements of individual muscles and that is easy to attach and configure.

In order to solve the above problems, the biosensor of the present invention is a biosensor worn on a living body as a subject, comprising: a light-receiving unit for receiving return light from the muscles of the body, an output unit for outputting information on deformation of the muscle at the one part based on a detection signal from the light-receiving unit corresponding to the received return light; Prepare.

The operation and other advantages of the present invention will become apparent from the detailed description that follows.

1 is a block diagram showing an outline of a biosensor according to an example; FIG. It is a figure for demonstrating the measurement principle of the biosensor which concerns on an Example. It is an example of a biological signal. It is an example of a detected signal before and after filtering. It is an example of the output of the biosensor according to the embodiment. It is an example of measurement results for each of a plurality of muscles. FIG. 10 is a diagram comparing the output of the biosensor according to the example and the output of an electromyogram;

An embodiment of the biosensor of the present invention will be described.

A biosensor according to an embodiment is a biosensor that is attached to a living body as a subject, and includes a light emitting unit that irradiates light to the living body and receives light that is returned from at least one part of the muscle of the living body. and an output unit for outputting information on deformation of a muscle in one region based on a detection signal from the light receiving unit corresponding to the received return light.

The biosensor is attached to a living body when used. Here, the biosensor may be attached to the living body by a dedicated attaching member such as a band, or may be attached to the living body by a medical paper tape or the like.

The light emitting unit emits light (red light to infrared light) having a wavelength of, for example, 660 μm to 940 μm. Incidentally, the wavelength of the light emitted from the light emitting unit is not limited to the wavelength described above, and may be appropriately set according to, for example, the object to be measured. The light-receiving unit receives return light from at least one part of the muscle of the living body.

For example, an output unit including a memory, a processor, etc. outputs information on deformation of a muscle in one region based on the detection signal from the light receiving unit.

Specifically, when the muscle of one part contracts, the physical distance between the light emitting part and the light receiving part is shortened and the muscle pressure increases compared to when the muscle is stretched (at the time of relaxation). . As a result, the amount of return light received by the light-receiving unit increases (that is, the signal level of the detection signal increases) when the muscle of one region contracts compared to when the muscle expands.

Therefore, the output unit outputs, for example, information indicating the signal level of the detection signal as information on deformation of the muscle of the one part.

According to the biosensor according to the present embodiment, information regarding the deformation of a muscle of one part is output based on the return light from the muscle of one part, so it is possible to detect an instantaneous change in the muscle of one part. is. In addition, since the light-receiving part receives most of the return light from the muscle closest to the biosensor (here, the muscle of one part), the detection signal from the light-receiving part is the closest to the biosensor. The effect of muscle deformation is dominant. That is, according to the biosensor, it is possible to detect only the deformation of the muscle at one site.

Furthermore, since the biosensor optically detects the deformation of the muscle, compared to an electromyograph that measures the weak potential of the body surface, the biosensor can be simpler in configuration and easier to handle. can.

In one aspect of the biosensor according to the present embodiment, the output unit determines that an increase in the signal level of the detection signal is contraction of the muscle of the one part.

According to this aspect, it is possible to relatively easily detect the deformation of the muscle at one site, which is extremely advantageous in practice.

In another aspect of the biosensor according to this embodiment, the light emitting section and the light receiving section are arranged on a flexible member.

According to this aspect, since the distance between the light-emitting portion and the light-receiving portion on the member can be kept constant, the measurement results obtained by the biosensor can be reproducible, and the biosensor can be easily attached to the living body. can be attached to

In another aspect of the biosensor according to this embodiment, the biosensor further comprises attenuation means for attenuating a signal component having a period longer than a predetermined period and included in the detection signal.

Research by the inventors of the present application has revealed that the detection signal includes the influence of a physiological response such as a change in cardiac output. The influence of the physiological response contained in the detection signal (that is, the component related to the physiological response of the signal) is longer than the fluctuation period of the detection signal caused by muscle changes.

Therefore, in this embodiment, the attenuation means attenuates the signal component that is included in the detection signal and has a period longer than a predetermined period. Therefore, according to this aspect, it is possible to suitably detect the deformation of the muscle at one site.

An embodiment of the biosensor of the present invention will be described with reference to the drawings. In the following examples, it is assumed that the subject is pedaling a bicycle.

A configuration of a biosensor according to an embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an overview of a biosensor according to an embodiment.

In FIG. 1A, the biosensor 100 includes a light emitting section 11, a light receiving section 12, a computing section 13, and a display section .

The light emitting unit 11 has a light emitting element such as an LED (Light Emitting Diode). The wavelength of the light emitted from the light emitting unit 11 may be appropriately set according to the object to be measured, for example.

The light receiving unit 12 has a light receiving element such as a PD (Photodioe). The light emitting unit 12 receives at least return light from a muscle to be measured of a living body as a subject. Here, "returned light" typically means light scattered or reflected by a living body. The light receiving unit 12 outputs a biological signal as a "detection signal according to the received return light" according to the present invention.

The calculation unit 13 is configured including a bandpass filter 131 and a normalization unit 132, as shown in FIG. 1(b). Details of the operation of the calculation unit 13 will be described later.

Here, the measurement principle of the biosensor 100 will be described with reference to FIG. FIG. 2 is a diagram for explaining the measurement principle of the biosensor according to the embodiment.

In FIG. 2, first, each of the light emitting unit 11 and the light receiving unit 12 of the biosensor 100 is attached to a site including the muscle to be measured of the subject. The light emitting unit 11 and the light receiving unit 12 do not have to be attached directly to the skin of the subject or via gel or cream. If it is clothes like this, it may be worn over the clothes.

Each of the light emitting unit 11 and the light receiving unit 12 is desirably arranged on a flexible member as shown in FIG. not shown). However, each of the light emitting unit 11 and the light receiving unit 12 does not have to be arranged on the flexible member. In addition, the "flexible member" according to the embodiment is an example of the "flexible member" according to the present invention.

Now, when a muscle contracts, the myosin filaments draw the actin filaments closer to the center, and the myosin filaments and the actin filaments overlap deeply with each other. shape (see FIG. 2(b)).

When the muscles contract, as shown in FIG. 2, the light emitting unit 11 and the light receiving unit 12 approach each other, and the angle between the normal to the light emitting surface of the light emitting unit 11 and the normal to the light receiving surface of the light receiving unit 12 changes. (In FIG. 2, it changes from “θ ₁ ” to “θ ₂ ”). As a result, the optical distance from the light emitting section 11 to the light receiving section 12 is shortened. Therefore, among the light emitted from the light emitting unit 11 and scattered or reflected by the muscle to be measured, the amount of light incident on the light receiving unit 12 increases.

In addition, intramuscular pressure rises during muscle contraction, restricting blood flow to active muscles, so the amount of light absorbed by the blood is reduced compared to when the muscles are relaxed. Therefore, when the muscle contracts, the amount of light scattered or reflected by the muscle being measured increases.

In other words, there is a correlation between the amount of light detected by the light receiving unit 12 (that is, the signal level of the biological signal to be output) and the change in the muscle to be measured.

When a subject is pedaling a bicycle, the subject's leg muscles contract and relax cyclically. When the biosensor 100 is attached to the subject's leg, the biosignal output from the light receiving unit 12 has a period synchronized with pedaling, as shown in FIG. 3, for example.

By the way, biological signals include the influence of physiological reactions such as changes in cardiac output. Specifically, as shown in FIG. 4(a), the biosignal as a whole fluctuates up and down in a relatively long cycle due to physiological reactions. It should be noted that the biomedical signals shown in FIG. 4 show fluctuations over about 10 minutes.

Therefore, in this embodiment, the band-pass filter 131 (see FIG. 1(b)) of the calculation unit 13 attenuates the component caused by the physiological reaction contained in the biological signal. As a result, the signal output from the bandpass filter 131 is as shown in FIG. 4(b).

The filtered signal output from the bandpass filter 131 is normalized by the normalization section 132 (see FIG. 1(b)). Specifically, the normalization unit 132 normalizes the filtered signal by regarding the maximum value of the signal amplitude of the signal after filtering as the maximally contracted state of the muscle and the minimum value of the signal amplitude as the non-contracted state of the muscle.

Subsequently, for example, the normalization unit 132 sets the maximum value of the normalized signal to the muscle contraction rate of 100%, and the minimum value of the normalized signal to the muscle contraction rate of 0%. Outputs information indicating time variation. It should be noted that the "information indicating the time variation of the muscle contraction rate" according to the embodiment is an example of the "information regarding the deformation of the muscle of one part" according to the present invention.

In this embodiment, the crank angle of the bicycle on which the subject is pedaling is detected by a crank angle sensor 20 (for example, a pedaling monitor). The display unit 14 of the biosensor 100 utilizes the crank angle detected by the crank angle sensor 20, and, for example, the information indicating the time variation of the muscle contraction rate output from the calculation unit 13 corresponds to the crank angle. (See Fig. 5).

Such a display allows the subject or the like to know the transition of the muscle contraction rate during pedaling, which is extremely advantageous in practice.

Moreover, the biosensor 100 is not limited to the pair of the light emitting unit 11 and the light receiving unit 12, and may include multiple pairs of the light emitting unit and the light receiving unit. With this configuration, rectus femoris (front thigh), niceps femoris (outer hamstrings), gluteus maximus (buttocks), and semitendinosus (inner hamstrings) are used for pedaling a bicycle, for example. ), tibialis anterior muscle (front calf), gastrocnemius muscle (rear calf), and the like (see FIG. 6).

As a result, for example, evaluation of proper use of muscles during pedaling, detection of unintended eccentric contraction (elongation muscle contraction), etc. can be performed, which is extremely advantageous in practice.

(Effect of this embodiment)
Electromyography is one of the most practical technologies that can assess the working state of muscles. Therefore, the measurement result of the biosensor 100 according to the present embodiment and the measurement result of the electromyograph will be compared with reference to FIG. The graphs shown in FIG. 7 all show variations in the muscle contraction rate for one cycle (that is, for a crank angle of 360 degrees).

Although the explanation of the principle of the electromyography is omitted, the electromyography detects action potentials caused by commands from the brain to contract muscles. On the other hand, the biosensor 100 optically detects muscle changes as described above. In other words, the biosensor 100 detects the result of muscle change. As described above, the electromyograph and the biosensor 100 have different measurement principles, but as shown in FIG. 7, the measurement results for each muscle are very similar.

Therefore, it can be said that the measurement result by the biosensor 100 is appropriate and has the same level of measurement accuracy as that of the electromyograph. In other words, the biosensor 100 can measure instantaneous muscle changes for each muscle with high accuracy, similar to an electromyograph.

However, since the electromyograph measures action potentials of muscles, it is possible to measure muscle contractions that do not involve muscle deformation, such as isometric contractions. On the other hand, the biosensor 100 measures muscle contraction from changes in the amount of light received due to muscle changes, and therefore cannot measure muscle contraction that does not involve muscle deformation.

In particular, if the light-emitting unit 11 and the light-receiving unit 12 can be physically fixed to a site including the muscle to be measured, the biosensor 100 can measure changes in the muscle, and is very easy to handle. be. In addition, the biosensor 100 only needs to be able to detect a signal at a speed at which the subject moves (for example, 10 Hz or less), so that the circuit configuration can be simplified and the size can be reduced. Therefore, the biosensor 100 can suitably measure the state of muscles in fields such as sports where the muscles are actively moved.

In the present embodiment, pedaling of a bicycle is taken as an example, but in the case of relatively simple periodic exercise such as jogging or running, the biosensor 100 performs measurements as shown in FIGS. Results can be displayed.

The "computing section 13" and the "bandpass filter 131" according to the embodiment are examples of the "output section" and the "attenuation means" according to the present invention, respectively.

The present invention is not limited to the above-described embodiments, and can be modified as appropriate within a range that does not contradict the gist or idea of the invention that can be read from the scope of claims and the entire specification. It is included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 11... Light-emitting part 12... Light-receiving part 13... Calculation part 14... Display part 20... Crank-angle sensor 100... Biosensor 131... Band-pass filter 132... Normalization part

Claims (1)

A biosensor attached to a living body as a subject,
a light emitting unit that irradiates the living body with light;
a light-receiving unit that receives return light from muscles of at least one part of the living body;
an output unit that outputs information about deformation of the muscle of the one part based on a detection signal from the light receiving unit corresponding to the received return light;
A biosensor comprising:

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