biosensor

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

[Technical Field]

[0001] The present invention relates to a biosensor, and more particularly to the technical field of a biosensor that measures the state of a living organism using optical technology. [Background technology]

[0002] As an example of this type of device, a device has been proposed that exerts muscle strength corresponding to the minimum value of oxygen saturation in the blood of the subject's muscles, estimated from a correlation table showing the correlation between oxygen saturation and muscle strength (see Patent Document 1).

[0003] Alternatively, a device has been proposed that is fixed to the subject's arm with a wearing band, has a pushing member that changes depending on the contraction state of the muscle, and outputs a detection signal corresponding to the movement displacement of the pushing member (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-70289 [Patent Document 2] Japanese Patent Application Publication No. 5-068675 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in Patent Document 1 monitors oxygen saturation, which decreases (i.e., changes appear) due to muscle contraction over a certain period of time, and therefore has the technical problem of being unable to detect instantaneous muscle contractions.The technology described in Patent Document 2 has the technical problem of being unable to detect individual muscle contractions, as the attachment band is wrapped around the subject's arm, and therefore detects the combined movement of, for example, an agonist muscle and an antagonist muscle.

[0006] Furthermore, electromyographs that measure the potential of the body surface have the technical problem that attaching the sensor requires time and care, and also requires a highly accurate detection circuit to detect weak potentials.

[0007] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a biosensor that can detect the movement of individual muscles and is easy to attach and configure. [Means for solving the problem]

[0008] In order to solve the above problems, the biosensor of the present invention is a biosensor that is attached to a living body and irradiates light onto the living body. Multiple A light-emitting portion; paired with each of the plurality of light emitting units, of the living body multiple Receives the return light from the muscle Multiple The light receiving unit and the front write back Light Light intensity In response to the above Multiple Based on the detection signal from the light receiving unit, multiple and an output unit that outputs information about the deformation of the muscle due to the contraction and extension of the muscle. The plurality of light-emitting units and the plurality of light-receiving units are disposed on a flexible member. .

[0009] The functions and other advantages of the present invention will become apparent from the following detailed description of the preferred embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an overview of a biosensor according to an embodiment; [Figure 2] 1A and 1B are diagrams for explaining the measurement principle of a biosensor according to an embodiment. [Figure 3] 1 is an example of a biological signal. [Figure 4] 10 is an example of a detection signal before and after filtering. [Figure 5] 10 is an example of an output of a biosensor according to an embodiment. [Figure 6] 10 is an example of measurement results for each of a plurality of muscles. [Figure 7]10 is a diagram comparing the output of a biosensor according to an embodiment with the output of an electromyogram. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of a biosensor according to the present invention will be described.

[0012] The biosensor of the embodiment is a biosensor that is attached to a living organism as a test subject, and comprises: a light-emitting unit that irradiates light onto the living organism; a light-receiving unit that receives return light from at least one muscle part of the living organism; and an output unit that outputs information regarding deformation of the muscle part based on a detection signal from the light-receiving unit in response to the received return light.

[0013] The biosensor is attached to a living body when in use. Here, the biosensor may be attached to the living body using a dedicated attachment member such as a band, or may be attached to the living body using, for example, medical paper tape.

[0014] The light emitting unit emits light with a wavelength of, for example, 660 μm to 940 μm (red light to infrared light). The wavelength of the light emitted from the light emitting unit is not limited to the above wavelengths and may be set appropriately depending on, for example, the object to be measured. The light receiving unit receives return light from at least one muscle part of the living body.

[0015] The output unit, which includes, for example, a memory, a processor, etc., outputs information relating to the deformation of the muscle at one site based on the detection signal from the light receiving unit.

[0016] Specifically, when a muscle in a certain area contracts, the physical distance between the light-emitting unit and the light-receiving unit decreases and muscle pressure increases compared to when the muscle is stretched (relaxed). As a result, when the muscle in a certain area contracts, the amount of returned light received by the light-receiving unit increases compared to when the muscle is stretched (i.e., the signal level of the detection signal increases).

[0017] Therefore, the output unit outputs, for example, information indicating the signal level of the detection signal as information regarding the deformation of the muscle at one site.

[0018] The biosensor according to this embodiment outputs information about the deformation of a muscle in a specific region based on the return light from the muscle, making it possible to detect even instantaneous changes in the muscle in that specific region. Additionally, since the light-receiving unit receives the most return light from the muscle closest to the biosensor (here, the muscle in the specific region), the detection signal from the light-receiving unit is dominated by the effect of the deformation of the muscle closest to the biosensor. In other words, the biosensor can detect only the deformation of the muscle in the specific region.

[0019] Furthermore, since the biosensor optically detects muscle deformation, it can be simpler in configuration and easier to handle than an electromyograph, which measures weak electrical potentials on the body surface.

[0020] In one aspect of the biosensor according to this embodiment, the output section determines that an increase in the signal level of the detection signal is a contraction of a muscle at a certain site.

[0021] According to this embodiment, deformation of a muscle in a certain region can be detected relatively easily, which is very advantageous in practical use.

[0022] In another aspect of the biosensor according to this embodiment, the light emitting section and the light receiving section are disposed on a flexible member.

[0023] According to this aspect, the distance between the light-emitting unit and the light-receiving unit on the component can be kept constant, making it possible to make the measurement results obtained by the biosensor reproducible and to easily attach the biosensor to a living organism.

[0024] In another aspect of the biosensor according to the present embodiment, the biosensor further comprises attenuation means for attenuating a signal component that is included in the detection signal and has a period longer than a predetermined period.

[0025] Research by the inventors of the present application has revealed that the detection signal includes the influence of physiological responses, such as changes in cardiac output, etc. The influence of physiological responses included in the detection signal (i.e., the component of the signal related to physiological responses) has a longer fluctuation period than the detection signal caused by changes in muscle.

[0026] Therefore, in this embodiment, the attenuation means attenuates signal components that are included in the detection signal and have a period longer than a predetermined period. Therefore, according to this aspect, deformation of the muscle in one region can be suitably detected. [Example]

[0027] An embodiment of the biosensor of the present invention will be described with reference to the drawings. In the following embodiment, it is assumed that the subject is pedaling a bicycle.

[0028] The configuration of a biosensor according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an outline of a biosensor according to an embodiment.

[0029] In FIG. 1(a), a biosensor 100 includes a light emitting unit 11, a light receiving unit 12, a calculation unit 13, and a display unit .

[0030] The light emitting unit 11 has a light emitting element such as an LED (Light Emitting Diode), etc. The wavelength of the light emitted from the light emitting unit 11 may be set appropriately depending on, for example, the object to be measured.

[0031] The light receiving unit 12 has a light receiving element such as a PD (Photodiode). The light emitting unit 12 receives at least return light from a muscle of a living body to be measured as a subject. Here, "return light" typically means light scattered or reflected by the living body. The light receiving unit 12 outputs a biosignal as a "detection signal corresponding to the received return light" according to the present invention.

[0032] 1(b), the calculation unit 13 includes a band-pass filter 131 and a normalization unit 132. The operation of the calculation unit 13 will be described in detail later.

[0033] Here, the measurement principle of the biosensor 100 will be described with reference to Fig. 2. Fig. 2 is a diagram for explaining the measurement principle of the biosensor according to the embodiment.

[0034] 2, first, the light-emitting unit 11 and the light-receiving unit 12 of the biosensor 100 are attached to a part of the subject's body that includes the muscle to be measured. Note that the light-emitting unit 11 and the light-receiving unit 12 do not have to be attached to the subject's skin directly or via gel or cream, and may be attached over clothing, such as clothing that fits tightly against the skin and allows the movement of the muscle to be measured to be detected.

[0035] It is desirable that each of the light-emitting unit 11 and the light-receiving unit 12 be arranged on a flexible member as shown in FIG. 2(a) (note that for ease of explanation, the flexible member is not shown in FIG. 2(b)). However, each of the light-emitting unit 11 and the light-receiving unit 12 does not have to be arranged on a flexible member. Note that the "flexible member" in the embodiment is an example of the "flexible member" according to the present invention.

[0036] When a muscle contracts, the myosin filaments pull the actin filaments closer to the center, causing them to overlap deeply with each other. Compared to the relaxed state of the muscle, the muscle fibers become denser and the overall muscle takes on a rounder shape (see Figure 2(b)).

[0037] When a muscle contracts, as shown in Fig. 2, the light-emitting unit 11 and the light-receiving unit 12 move closer to each other, and the angle formed 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 "θ1" to "θ2"). As a result, the optical distance from the light-emitting unit 11 to the light-receiving unit 12 decreases. Therefore, of the light emitted from the light-emitting unit 11 and scattered or reflected by the muscle being measured, the amount of light incident on the light-receiving unit 12 increases.

[0038] In addition, when a muscle contracts, intramuscular pressure increases, restricting blood flow to the active muscle, so the amount of light absorbed by the blood is reduced compared to when the muscle is relaxed. Therefore, when the muscle contracts, the amount of light scattered or reflected by the muscle being measured increases.

[0039] That is, there is a correlation between the amount of light detected by the light receiving section 12 (that is, the signal level of the output biological signal) and the change in the muscle being measured.

[0040] When a subject pedals a bicycle, the muscles in the subject's legs periodically contract and relax. When the biosensor 100 is attached to the subject's legs, the biosignal output from the light-receiving unit 12 has a period synchronized with the pedaling, as shown in FIG.

[0041] Incidentally, the biological signal includes the influence of physiological responses, such as changes in cardiac output. Specifically, as shown in Fig. 4(a), the entire biological signal fluctuates up and down over a relatively long period due to physiological responses. The biological signal shown in Fig. 4 shows fluctuations over a period of approximately 10 minutes.

[0042] Therefore, in this embodiment, the components caused by physiological reactions included in the biological signal are attenuated by the band-pass filter 131 (see FIG. 1(b)) of the calculation unit 13. As a result, the signal output from the band-pass filter 131 becomes as shown in FIG. 4(b).

[0043] The filtered signal output from the band-pass filter 131 is normalized by the normalization unit 132 (see FIG. 1(b)). Specifically, the normalization unit 132 normalizes the filtered signal by defining the maximum value of the signal amplitude of the filtered signal as a maximum contraction state of the muscle and the minimum value of the signal amplitude as a non-contraction state of the muscle.

[0044] Next, the normalization unit 132 outputs information indicating the time variation of the muscle contraction rate, for example, by setting the maximum value of the normalized signal to a muscle contraction rate of 100% and the minimum value of the normalized signal to a muscle contraction rate of 0%. Note 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 a muscle at a certain site" according to the present invention.

[0045] In this embodiment, the crank angle of the bicycle on which the subject is pedaling is detected by a crank angle sensor 20 (e.g., a pedaling monitor). The display unit 14 of the biosensor 100 uses the crank angle detected by the crank angle sensor 20 to display, for example, information indicating time variation in muscle contraction rate output from the calculation unit 13 in association with the crank angle (see FIG. 5).

[0046] Such a display allows the subject to know the transition of the muscle contraction rate during pedaling, which is extremely advantageous in practical use.

[0047] Furthermore, the biosensor 100 may include multiple pairs of light-emitting units and light-receiving units, rather than being limited to a pair of light-emitting unit 11 and light-receiving unit 12. With this configuration, it is possible to detect the transition of the contraction rate of each of multiple muscles used in pedaling a bicycle, such as the rectus femoris (front of the thigh), biceps femoris (outer hamstrings), gluteus maximus (buttocks), semitendinosus (inner hamstrings), tibialis anterior (front of the calf), and gastrocnemius (rear of the calf) (see FIG. 6).

[0048] As a result, it is possible to, for example, evaluate the use of different muscles when pedaling, detect unintentional eccentric contractions (elongation muscle contractions), etc., which is extremely advantageous in practical use.

[0049] (Effects of this embodiment) An electromyograph is one of the most practical techniques for evaluating the state of muscle movement. Therefore, the measurement results of the biosensor 100 according to this embodiment and the measurement results of the electromyograph are compared with each other with reference to Fig. 7. The graphs shown in Fig. 7 each show the fluctuations in the muscle contraction rate for one cycle (i.e., 360 degrees of crank angle).

[0050] Although an explanation of the principles of an electromyograph is omitted here, an electromyograph detects action potentials resulting from commands from the brain to contract muscles. In contrast, as described above, the biosensor 100 optically detects changes in muscles. In other words, the biosensor 100 detects the results of muscle changes. Thus, although the measurement principles of the electromyograph and the biosensor 100 are different, as shown in FIG. 7, the measurement results for each muscle are very similar.

[0051] Therefore, it can be said that the measurement results obtained by the biosensor 100 are valid and have the same level of measurement accuracy as an electromyograph. In other words, the biosensor 100 can measure instantaneous muscle changes for each muscle with high accuracy, just like an electromyograph.

[0052] However, since an electromyograph measures the action potential of muscles, it can also measure muscle contractions that do not involve muscle deformation, such as isometric contractions.On the other hand, the biosensor 100 measures muscle contractions from changes in the amount of received light caused by muscle changes, and therefore cannot measure muscle contractions that do not involve muscle deformation.

[0053] In particular, the biosensor 100 can measure changes in the muscle as long as the light-emitting unit 11 and the light-receiving unit 12 can be physically fixed to a location containing the muscle to be measured, and it is very easy to handle. Furthermore, the biosensor 100 only needs to be able to detect signals at a speed similar to the subject's movement speed (e.g., 10 Hz or less), which allows for, for example, a simplified circuit configuration and miniaturization. Therefore, the biosensor 100 can be used effectively to measure muscle conditions in fields where muscles are actively moved, such as sports.

[0054] In this embodiment, bicycle pedaling is used as an example, but for relatively simple periodic exercise such as jogging or running, the biosensor 100 can display measurement results such as those shown in Figures 5 to 7.

[0055] The "calculation unit 13" and the "bandpass filter 131" according to the embodiment are examples of the "output unit" and the "attenuation means" according to the present invention, respectively.

[0056] The present invention is not limited to the above-described embodiments, but can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and biosensors with such modifications are also included in the technical scope of the present invention. [Explanation of symbols]

[0057] 11...light emitting unit, 12...light receiving unit, 13...calculating unit, 14...display unit, 20...crank angle sensor, 100...biometric sensor, 131...band pass filter, 132...normalizing unit

Claims

1. A biosensor to be attached to a living body, a plurality of light emitting units that irradiate the living body with light; a plurality of light receiving units that are paired with the plurality of light emitting units, respectively, and receive return light from a plurality of muscles of the living body; an output unit that outputs information about the deformation of the muscles due to contraction and extension based on detection signals from the light receiving units corresponding to the amount of light returned by the returned light; Equipped with The plurality of light-emitting units and the plurality of light-receiving units are disposed on a flexible member. A biosensor characterized by:

2. The biosensor according to claim 1 , wherein the output unit determines an increase in the signal level of the detection signal as a contraction of the plurality of muscles.

3. The biosensor described in Claim 1, characterized in that the output unit detects the contraction rates of the multiple muscles based on the detection signal.

4. 4. The biosensor according to claim 1, further comprising attenuation means for attenuating a signal component included in the detection signal and having a period longer than a predetermined period.

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