JP2008284354A - Biological impedance measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biological impedance measuring apparatus, measuring the biological impedance of a person to be measured even when the person to be measured steps on any part of a step provided with a foot electrode. <P>SOLUTION: This biological impedance measuring apparatus includes at least three electrodes in which foot electrodes coming into contact with both feet of the person to be measured are disposed spaced apart from each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bioimpedance measurement device, and more particularly to the structure of a foot electrode of a bioimpedance measurement device.

  The bioelectrical impedance analysis (BIA) technique is a technique for measuring moisture in a human body using an electrical method. When a weak alternating current electrical signal is sent to the human body, electricity flows along the highly conductive body moisture. The amount of moisture determines the width of the passage through which electricity flows, and this is expressed as a measured value called impedance.

  The impedance (Z) is a force that disturbs electricity when it flows. The impedance is engineeringly determined by the vector sum of electric resistance (R) and reactance (Xc).

However, in the case of the human body, there is a difference between impedance and electrical resistance value of only about 2 to 3Ω, and this difference is negligibly small. Therefore, in the field of bioimpedance measurement (BIA), impedance is an electrical resistance value. It appears to be the same as the value.

  The electrical resistance (R) of the conductor is directly proportional to the specific resistance (ρ) and the length (L) of the conductor, and inversely proportional to the cross-sectional area (A).

From this equation, the volume (V) of the conductor can be expressed as a function of the specific resistance (ρ), the length (L) of the conductor, and the electrical resistance (R).

When this equation is applied to the human body, the volume (V) of the conductor corresponds to the moisture of the human body, the specific resistance (ρ) corresponds to the resistance per unit volume of body moisture (C), and the length of the conductor ( L) corresponds to the height of the human body, and the electric resistance (R) corresponds to the human body resistance, that is, the bioimpedance of the human body. Therefore, the equation for obtaining the body moisture is as follows.

The height of the human body is a measurable value, and the resistance per unit volume (C) of the body water is expressed as a constant value because a certain amount of electrolyte per unit volume is dissolved in the body water. Therefore, if the bioimpedance value of the human body is known, the water content of the human body can be obtained.

  The body components that make up the body are mainly composed of four types of components: body moisture, protein, body fat, and mineral (bone). The proportion of these four components in weight is about 55: 20: 20: 5, although there are gender and individual differences. By the way, if the body water content and the body fat content are known, the remaining components can be obtained. This is because protein and body water are the main components that form muscle, and they have a mutually proportional relationship. That is, healthy muscles are about 73% water and the remaining 27% are protein. Inorganic is a main component that mainly forms bone, and the weight of bone has a close relationship with muscle mass. Therefore, since the protein amount and the inorganic mass can be obtained from the body water amount, if the body water amount and the body fat amount are known, all of the four components constituting the body component are separated.

  That is, if the bioimpedance value of the human body is obtained, the moisture content of the human body can be obtained, the protein amount and the inorganic mass can be obtained from this body moisture content, and the protein amount and the inorganic mass can be obtained from the body moisture content. Subtract the body fat mass. Accordingly, it is possible to acquire clinical information such as body fat of the human body through measurement of the bioelectrical impedance of the human body.

  FIG. 1 is a diagram illustrating an example of a measuring device for bioimpedance of a human body. As shown in the figure, in order to measure the bioimpedance of the human body, adhesive electrodes used for ECG (Electro Card Gram) and the like are attached to the right wrist and back of the human body and the back of the right ankle and foot. Then, these electrodes are connected to a bioimpedance measuring device. The bioimpedance measuring device applies a current (i) to electrodes on the back of the hand and the back of the foot. The current flows through the human body through the right arm, torso, and right foot, and at this time, the voltage (V) between the electrodes on the back of the hand and the back of the foot is measured by a bioimpedance measuring device. Then Ohm's law

From this, the human body resistance (R) value, that is, the bioelectrical impedance value is obtained. By substituting this body resistance (R) value into the formula for determining body moisture, the amount of moisture in the human body can be determined, and as described above, the amount of protein and inorganic mass can be determined from the amount of body moisture. Thus, when the protein amount and the inorganic mass are subtracted from the body water amount, the body fat amount is obtained. Therefore, it is possible to determine the composition ratio of body moisture, protein, body fat, and mineral, which are the four components that constitute the body component of the human body, by measuring the bioimpedance of the human body. Is possible.

  FIG. 2 is a diagram illustrating the principle of measuring bioimpedance for each human body part, and FIG. 3 is an example of a bioimpedance measuring apparatus that can measure bioimpedance for each human body part by applying the principle illustrated in FIG. FIG.

  The human body arms, legs, and torso have considerably different body resistance (bioimpedance) magnitudes. Human resistance is very high at about 250Ω for the arm, but only about 25Ω for the torso. Thus, as shown in FIG. 1, the large difference in bioimpedance for each part is very large in the accuracy of the bioimpedance measuring apparatus that measures only the impedance of the whole body without distinguishing between arms, legs, and torso. affect.

  For example, when 1 kg muscle component is further added to the torso compared to the standard body shape, it causes a small change in resistance value of 2-3 Ω, but when the same amount of muscle is added to the arm, 20 to 20 A large resistance difference of 30Ω is brought about. In other words, the sensitivity to the bioimpedance greatly varies depending on what part of the human body is the same amount of water and muscle mass.

  In the case of the bioimpedance measuring apparatus as shown in FIG. 1, the whole body resistance (bioimpedance) from the wrist to the ankle is measured, and the human body resistance value is the bioimpedance of each of the arm, torso, and foot. The sum was about 500Ω. If 1 kg of muscle is applied to the torso, the human body resistance value changes to 503Ω, but if the same amount is applied to the arm, the human body resistance value changes greatly to about 530Ω.

  A healthy human body maintains a relatively proportional relationship between the size of arms, legs, and torso, and this problem does not appear remarkably, but as the amount of activity decreases with age, However, such a phenomenon appears as a measurement error of a conventional bioimpedance measuring apparatus. Therefore, the conventional bioimpedance measuring device is a great measure for patients whose body shape is different from the average adult man and woman, such as patients, athletes, torso people, severely obese patients, the elderly and children. Represents an error.

  FIG. 2 shows an electrical model of a human body for measuring bioimpedance for each human body part. The electrical model of the human body illustrated in FIG. 2 is different from that illustrated in FIG. 1 and does not assume that the human body is a conductor having a single human resistance, and each of the right arm, the left arm, the trunk, the right foot, and the left foot. Are assumed to be conductors having five human resistances.

In the same figure, the electrical resistance for each part is indicated as R _RA , R _LA , R _T , R _RL , R _LL . Resistors R ₁ and R ₂ represent the resistance between the thumb and palm of the hand, and extend outward by making a branch at the wrist. Resistors R ₃ and R ₄ represent the resistance between the millet and the forefoot part, and branch out at the ankle part and extend outward.

  For the measurement, if the person to be measured takes a posture after stepping on the foot electrodes E5, E6, E7, E8 and holding the hand electrodes E1, E2, E3, E4, the measuring device for bioimpedance To automatically measure the bioelectrical impedance for each human body part and output the result. As the hand electrode and the foot electrode, eight metal surfaces made of stainless steel plates are used.

Examining the method of measuring the different parts of the human body resistance, for example, to measure the human body resistance R _RA right arm allows a current to flow between the hand electrodes E1 and feet electrodes E5, hand electrode E2 and hand A voltage is measured between the electrode E4. The current flows through R ₁ → R _RA → R _T → R _RL → R ₃ , and the voltage is measured in a loop formed by R ₂ → R _RA → R _LA → R ₂ . Loop passage and voltage is measured the current flows is superimposed by R _RA measures the human body resistance R _RA right arm. In such measurement, when the input impedance of the voltage measurement terminal of the bioimpedance measuring device is considerably large, the terminal human resistance value applied to R _{1 to} R ₄ does not affect the measurement of the right arm resistance. This means that even when the contact resistance changes and the resistance values of R _{1 to} R ₄ change, the measurement of the resistance value for each part of the human body is not affected.

The bioimpedance of the other part on the right side is measured in the same manner as the measurement of the right arm. By passing a current between the hand electrode E1 and the foot electrode E5 and measuring the voltage between the hand electrode E4 and the foot electrode E8, the human body resistance _RT of the torso is reduced between the foot electrode E6 and the foot electrode E8. The human body resistance R _RL of the right foot can be obtained by measuring the voltage between them. In order to obtain the bioelectrical impedance for each part on the left side, a current is passed between the hand electrode E3 and the foot electrode E7, and the voltage between the hand electrode E2 and the hand electrode E4 is measured to measure the human body resistance of the left arm. The human body resistance R _LL of the left foot can be obtained by measuring the voltage between R _LA and the foot electrode E6 and the foot electrode E8.

  The bioimpedance measurement technique for each part is performed by distinguishing bioimpedance into right arm, left arm, trunk, right foot, and left foot. Each part is not completely cylindrical, but it is not a big difference such as a difference between an arm and a torso, so that the accuracy can be greatly increased. Actually, the cross-sectional area of the wrist and the upper arm can show a difference of 2-3 times even in the arm, but when measuring the bioelectrical impedance, the error is only 2-3%.

  The bioimpedance measuring apparatus for measuring bioimpedance for each human body part shown in FIGS. 2 and 3 has a measurement function for each part for measuring the right arm, left arm, trunk, right foot, and left foot, respectively. The accuracy of measurement can be greatly improved by removing errors caused by individual differences due to changes in individual parts. In addition, through the analysis of body components provided by region, body balance such as upper body development and lower body weakness and edema diagnosis by region can provide very useful clinical information.

  However, the bioimpedance measuring apparatus shown in FIG. 1 is not only troublesome in attaching and detaching electrodes, but also has a problem that requires a trained measurer because it must be attached to an accurate position. It was. In addition, when the person to be measured lies down, body moisture flows from the lower body to the upper body and redistributes, but at this time, it takes about 5-10 minutes, takes a lot of time for measurement, and places a large bed. Requires area.

  The bioimpedance measuring apparatus shown in FIGS. 2 and 3 adopts a touch structure in which electrical connection is established by bringing a human skin into contact with an electrode made of a conductor. Measurement accuracy and time loss, which are disadvantages of the impedance measurement device, are minimized to improve measurement accuracy. This bioimpedance measuring apparatus does not have the trouble of attaching and detaching electrodes, and for such convenience, the 8-point electrode method can be applied not only to the right hand and foot but also to the left hand and foot. The 8-point electrode method has an advantage that a measurement technique for each part that can measure impedance for each part of the human body can be easily obtained.

  However, the bio-impedance measuring device having a touch structure as shown in FIGS. 2 and 3 includes a fixed foot electrode 1 that comes into contact with the sole of the subject's foot and the heel of the foot. . One of the foot electrodes 1 is an electrode 1a for applying a current to the human body, and the other is an electrode 1b for measuring a voltage. By separating the current electrode 1a and the voltage electrode 1b, the body contact area can be increased, which is advantageous for obtaining accurate measurement values such as reducing the contact resistance. In this bioimpedance measurement device with a touch-type structure, when measuring the bioimpedance, the person to be measured contacts the sole of the foot with one electrode, and at the same time, precisely touches the heel of the foot with the other electrode. Accurate bioimpedance values can be obtained.

  Therefore, when the person to be measured stands without stepping on the electrode or the foot is small like a child and the foot cannot be in contact with the two electrodes at the same time, the measurement of bioimpedance becomes troublesome. Also, from the user's standpoint, it is time consuming and inconvenient to accurately position the foot electrode. In fact, most elderly and inexperienced people at the health center have difficulty measuring accurately without the help of professionals, one of the main reasons for this foot electrode.

  Furthermore, when the hand electrode is used at the same time, there is no room for the person to be measured to move his / her foot back and forth, so the hand electrode must be manufactured in a flowable structure. The hand electrode 2 is provided by being connected with a string from the main body or is provided at the tip of a bar having a hinge structure, which requires an additional design for the hand electrode installation structure. However, there is a problem that the manufacturing cost increases.

  The present invention is for solving the above-described problems, and an object thereof is to provide a foot electrode structure that can be easily used by a user.

  Furthermore, an object of the present invention is to provide a foot electrode structure capable of achieving measurement accuracy without extra effort during measurement.

  In addition, the present invention additionally improves the convenience of use while simplifying the structure of the hand electrode by giving flowability to the measurement subject's foot position and reducing the overall manufacturing cost. With a purpose.

  According to one aspect of the present invention for achieving the above object, a bioimpedance measuring device according to the present invention includes at least three foot electrode bodies that are in contact with each of both feet of the measurement subject and are spaced apart from each other. An electrode is provided.

  On the other hand, according to an additional aspect of the present invention, the bioimpedance measurement device according to the present invention includes at least three electrodes that are in contact with each of the feet of the measurement subject but are spaced apart from each other. It is characterized by comprising a foot electrode body and a hand electrode body which is brought into contact with both hands of the measurement subject.

  Therefore, the measurement subject can measure the bioelectrical impedance of the measurement subject regardless of the part of the platform on which the foot electrode is provided, and further, the measurement subject's foot can be freely moved. A hand electrode having a fixed structure can be used, and the device structure is simplified, thereby reducing the design and manufacturing costs.

  The bioimpedance measuring apparatus according to the present invention can measure the bioimpedance of the subject even if the subject steps on any step of the platform on which the foot electrode is provided. Since it can be moved, a hand electrode having a fixed structure can be adopted, which has a very useful effect that the structure of the apparatus can be simplified and the design and manufacturing costs can be reduced.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention through the described preferred embodiments. FIG. 4 is an external view of an embodiment of a bioimpedance measuring apparatus according to the present invention, and FIG. 5 is a block diagram illustrating a configuration of an embodiment of the bioimpedance measuring apparatus according to the present invention.

  As shown in the drawings, a bioimpedance measuring apparatus 100 according to the present invention includes a step 10 on which a measurement subject can step with his / her foot, an upper body 20 for user input and screen display, and the step 10 and the upper portion. A support member 30 for supporting the body 20, and an operation unit 110, a display unit 120, a foot electrode body 130, which are provided at appropriate portions of the step platform 10, the upper body 20, and the support member 30, An impedance measurement unit 140 and a control unit 150 are included.

  The operation unit 110 is an input unit such as a key button or a touch pad for performing user input for measuring bioimpedance, and is preferably provided on the upper body 20 to facilitate user operation. The display unit 120 is a display unit such as an LCD for displaying the measurement result of the bioimpedance and notifying the user, and is preferably provided on the upper body 20 so that the user can easily display the measurement result.

  The foot electrode body 130 is a portion in contact with each of both feet of the measurement subject, and is provided on the upper surface of the step platform 10. At this time, the foot electrode body 130 is provided with at least three electrodes that are spaced apart from each other, and the electrodes are always in contact with the feet of the subject regardless of the step of the subject. This makes it easier to measure the bioimpedance of the person being measured.

  Meanwhile, the electrodes of the foot electrode body 130 that are spaced apart from each other include a current application electrode 131 and a voltage measurement electrode 132. The current application electrode 131 is a terminal for connecting a power source (not shown) in order to apply a current to the human body through the feet of the person to be measured in contact with the current application electrode 131. The voltage measuring electrode 132 is a terminal for connecting an impedance measuring circuit in order to detect a human body resistance (bioimpedance) flowing through the human body through the measurement subject's foot in contact with the voltage measuring electrode 132.

  The impedance measurement unit 140 is an impedance measurement circuit that measures the bioelectrical impedance of the measurement subject, and can be configured in any one of the step platform 10, the upper body 20, and the support member 30. The control unit 150 is a microcontroller that controls the entire apparatus so as to process the bioimpedance measured by the impedance measurement unit 140 and display the measurement result of the bioimpedance through the display unit 120. It can be provided in the form of an IC chip inside any one of the step board 10, the upper body 20 and the support member 30.

  If the bioimpedance measurement operation of the bioimpedance measuring apparatus according to the present invention having the above-described configuration is examined, if the measured person touches the foot 10 to measure the bioimpedance, the measured object becomes any of the steps 10. Even when the part is stepped on, the foot of the person to be measured is always in contact with the current application electrode 131 and the voltage measurement electrode 132 which are arranged separately from each other of the foot electrode body 130 formed on the upper surface of the platform 10.

  In this state, if a user input for measuring bioimpedance is performed through the operation unit 110, a current is applied to the human body of the measurement subject through the current application electrode 131 under the control of the control unit 150, and the voltage The measurement subject's bioimpedance is measured by the method described with reference to FIG. 2 through the impedance measurement unit 140 connected to the measurement electrode 132, and the measurement result of the bioimpedance is displayed through the display unit 120.

  Therefore, the bioimpedance measurement device according to the present invention differs from the conventional bioimpedance measurement device in that the electrode is always in contact with the measurement subject's feet regardless of the step of the measurement subject. The measurement subject does not need to be careful to accurately touch the electrode with the foot, and the bioimpedance of a child with a small foot can be measured, so that the measurement of the bioimpedance for the measurement subject is very easy.

  On the other hand, according to the additional aspect of the present invention, it is desirable that the current applying electrodes 131 and the voltage measuring electrodes 132 of the foot electrode body 130 that are spaced apart from each other are alternately arranged. At this time, the current application electrode 131 and the voltage measurement electrode 132 may be arranged at non-constant intervals, but it is desirable to arrange them at regular intervals.

  That is, in this embodiment, the current application electrodes 131 and the voltage measurement electrodes 132 are alternately arranged with a distance of, for example, about 3 cm, and the current application electrodes 131 are gathered to collect power supply input terminals (not shown). ), The voltage measuring electrode 132 is collected and connected to an impedance measuring terminal (not shown), so that it has a 4-pole electrode method effect as shown in FIG. Decrease greatly. In the present invention according to this embodiment, since the small current application electrodes 131 and the voltage measurement electrodes 132 that are alternately arranged in a state of being separated from each other are brought into contact with the feet of the person to be measured, the contact resistance is greatly reduced. sell.

  On the other hand, according to an additional aspect of the present invention, the bioimpedance measurement apparatus further includes a hand electrode body 160 that is brought into contact with both hands of the measurement subject. In the drawing, 161 is a current application electrode, and 162 is a voltage measurement electrode. At this time, by providing the hand electrode body 160 so as to be fixed on the upper body 20 or the support member 30, the hand electrode is connected with a string or a conventional bioimpedance measurement embodied in a bar shape. Compared to the device, the device structure is simplified, and the design and manufacturing costs are reduced.

  Of course, a conventional bioimpedance measuring device can also be provided with a fixed hand electrode, but in this case, the subject cannot move his / her foot freely, so when a fixed hand electrode is provided Since the posture is not constant depending on the height of the subject when the subject grasps the hand electrode with his hand, the measurement value of the bioimpedance is not consistent. In order to solve such a problem, the conventional bioimpedance measurement device is provided with a hand electrode connected with a string, or a bar-shaped hand electrode that is extended to both sides of the measurement subject. In this case, an additional design for the connection structure of the hand electrode is required, and there is a problem that the manufacturing cost of the hand electrode increases.

  However, the bioimpedance measuring apparatus according to the present invention can measure the bioimpedance of the subject regardless of the part of the step where the subject is provided with the foot electrode. It can move freely back and forth, and can adopt a fixed posture even if it adopts a fixed hand electrode structure. That is, in the case of a small child, move the foot near the hand electrode body side to take the hand electrode body, and in the case of a tall adult, move the foot away from the hand electrode body to move the hand electrode body. If it takes, the bioimpedance can be measured in a stable posture. When the hand electrode having such a fixed structure is employed, the price competitiveness at the time of sale is excellent by reducing the manufacturing cost.

  Meanwhile, according to an additional aspect of the present invention, although not shown in the drawings, the hand electrode body 160 includes at least three electrodes spaced apart from each other like the foot electrode body 130. In this way, the electrode can always be brought into contact with the hand of the subject regardless of the part of the subject to be gripped. The electrode includes a current application electrode and a voltage measurement electrode, and the current application electrode and the voltage measurement electrode that are spaced apart from each other are preferably arranged alternately. At this time, the current application electrode and the voltage measurement electrode may be arranged at non-constant intervals, but it is desirable to arrange them at regular intervals.

  6 to 9 show various embodiments of the array structure of the foot electrodes of the bioimpedance measuring apparatus according to the present invention.

  FIG. 6 is a diagram showing bar-shaped slit-type foot electrode bodies alternately arranged with a bar-shaped current application electrode and a voltage measurement electrode spaced apart from each other.

  FIG. 7 is a diagram showing a matrix-type foot electrode body in which a square current application electrode and a voltage measurement electrode are alternately arranged in a separated state.

  FIG. 8 is a diagram showing a square ring type foot electrode body in which a square ring-shaped current application electrode and a voltage measurement electrode are alternately arranged in a separated state.

  FIG. 9 is a view showing a V-shaped slit-type foot electrode body in which a V-shaped current application electrode and a voltage measurement electrode are alternately arranged in a separated state.

  The foot electrode body of the bioimpedance measuring device according to the present invention has all the forms alternately arranged with the current applying electrode and the voltage measuring electrode separated from each other in addition to the forms shown in FIGS. Includes the structure of the foot electrode.

  By configuring as described above, the bioimpedance measuring apparatus according to the present invention can measure the bioimpedance of the subject regardless of the part of the step where the subject is provided with the foot electrode. Further, the measurement subject's foot can be freely moved, and a hand electrode having a fixed structure can be employed, thereby achieving the above-described object of the present invention.

  Although the present invention has been described with reference to the preferred embodiments referred to by the accompanying drawings, various modifications can be made without departing from the scope of the present invention without departing from the scope of the present invention. Obviously, variations are possible.

  The present invention is applicable in the field of bioimpedance measurement devices.

It is a figure which shows an example of the measuring apparatus of the conventional bioimpedance. It is a figure which shows the electrical model of the human body for measuring bioimpedance for every human body site | part. It is a figure which shows an example of the measuring device of the bioimpedance which can measure bioimpedance for every conventional human body site | part. It is an external view by one Embodiment of the measuring apparatus of the bioimpedance by this invention. 1 is a block diagram illustrating the configuration of an embodiment of a bioimpedance measurement apparatus according to the present invention. It is a figure which shows an example of the arrangement structure of the foot electrode of the measuring apparatus of the bioimpedance by this invention. It is a figure which shows the other example of the arrangement structure of the foot electrode of the measuring apparatus of the bioimpedance by this invention. It is a figure which shows the other example of the arrangement structure of the foot electrode of the measuring apparatus of the bioimpedance by this invention. It is a figure which shows the further another example of the array structure of the foot electrode of the measuring apparatus of the bioimpedance by this invention.

Explanation of symbols

10 Steps
20 Upper body 30 Support member
DESCRIPTION OF SYMBOLS 100 Bioimpedance measuring apparatus 110 Operation part
120 display unit 130 foot electrode body
131 Electrode for current application 132 Electrode for voltage measurement
140 Impedance measurement unit 150 Control unit
160 Hand electrode body

Claims (10)

A display unit for displaying the measurement result of bioimpedance;
A foot electrode body in contact with each of both feet of the measurement subject;
An impedance measurement unit for measuring the bioelectrical impedance of the measurement subject;
In the bioimpedance measuring apparatus, comprising a control unit that controls the bio-impedance measured by the impedance measuring unit to display the measurement result of the bio-impedance through the display unit.
A bioimpedance measuring apparatus comprising at least three electrodes, the foot electrode bodies being spaced apart from each other.   The bioimpedance measuring apparatus according to claim 1, wherein the electrode includes a current applying electrode and a voltage measuring electrode.   The bioelectrical impedance measuring apparatus according to claim 2, wherein the current application electrodes and the voltage measurement electrodes are alternately arranged.   4. The bioimpedance measurement apparatus according to claim 3, wherein the current application electrode and the voltage measurement electrode are arranged at regular intervals.   The bioimpedance measurement apparatus according to any one of claims 1 to 4, wherein the bioimpedance measurement apparatus further includes a hand electrode body that is brought into contact with both hands of the measurement subject.   The bioimpedance measurement apparatus according to claim 5, wherein the bioimpedance measurement apparatus further includes an operation unit for user input.   The bioimpedance measuring apparatus according to claim 6, wherein the hand electrode body includes at least three electrodes spaced apart from each other.   The bioimpedance measuring apparatus according to claim 7, wherein the electrode includes a current applying electrode and a voltage measuring electrode.   9. The bioimpedance measurement apparatus according to claim 8, wherein the current application electrodes and the voltage measurement electrodes are alternately arranged.   10. The bioimpedance measurement apparatus according to claim 9, wherein the current application electrode and the voltage measurement electrode are arranged at regular intervals.