JP6015534B2 - Biological information measuring apparatus and biological information measuring method - Google Patents

Description

  The present invention relates to a biological information measuring device and a biological information measuring method. More specifically, the present invention relates to a biological information measuring apparatus and a biological information measuring method capable of measuring the impedance (biological impedance) of a human body even when the measurement electrode is not in direct contact with the human skin.

Conventionally, bioelectrical impedance is measured by flowing an alternating current of about 0.5 mA (for example, 50 kHz) through a hand or foot and detecting a voltage drop or the like at a measurement site. Many studies have been conducted on lean body weight, the effect of obesity, muscle mass, and the like using bioimpedance measurement. Furthermore, in the medical field, attempts have been made to quantify edema (swelling) by measuring bioimpedance and observe local increase and decrease of body fluids.
In the field of automobiles, in order to detect a driver's disease, fatigue, and the like, an attempt has been made to accurately measure biological information of a human body during driving. For example, a measurement device that detects an electrocardiogram signal of a driver by providing an electrocardiogram signal detection device on a steering wheel is known. In such a measuring apparatus, an invention is disclosed in which a plurality of electrodes are provided on a steering wheel to improve measurement accuracy of a driver's biological information such as an electrocardiogram waveform and a heartbeat signal (see, for example, Patent Document 1). .) In the biological information measuring device described in Patent Document 1, four electrodes are provided on the gripping portion of the steering wheel to determine the contact impedance of each electrode, and a set of electrodes to be used for measuring biological signals is determined using the result. ing.

JP 2008-237379 A

Conventionally, in order to electrically measure biometric information such as bioimpedance and electrocardiographic signals, it has been necessary to directly touch the skin with electrodes for measurement. Even if the electrode is in contact with the skin, if the contact state is not good, the contact impedance increases, and it is difficult to measure the voltage drop due to the bioelectrical impedance. Furthermore, there is a problem that bioimpedance cannot be measured when clothing is interposed between the human skin and the electrodes.
In addition, when measuring biological information of a driver of a vehicle such as an automobile, it is necessary to detect the biological information in an unconstrained state. Therefore, as described in Patent Document 1, biological information such as an electrocardiographic waveform and a heartbeat signal is measured by providing an electrode on the steering wheel. However, even if the electrode is provided on the steering wheel, the driver's skin needs to be in direct contact with the electrode, and it is difficult to maintain a good electrical contact state. Further, when the driver is wearing gloves or a cover is attached to the steering wheel, there is a problem that measurement cannot be performed.
Furthermore, as described above, an attempt has been made to evaluate edema or fatigue due to long-term sitting or the like by monitoring bioelectrical impedance.
In any of the above cases, it is required to solve the problem that the electrode has to be directly attached to the human body or the electrode has to be provided at a site where the skin directly touches.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a biological information measuring device and a biological information measuring method capable of measuring biological impedance even when the skin is not in direct contact with the electrode.

In order to solve the above problem, the biological information measuring apparatus according to the first aspect of the present invention is directly connected to the human body in each of the first region and the second region set at positions separated along a conduction path through which a current flows in the human body. Or four electrodes in contact with each other through an insulator, two electrodes arranged in the direction of the conduction path in the first region, and two electrodes arranged in the direction of the conduction path in the second region; A selection means for selecting one set of electrodes from the combination of the four electrodes; a measurement means for supplying an alternating current between the set of electrodes selected by the selection means and measuring an impedance between the electrodes; Impedances (Z1 and Z2) measured for two combinations of electrodes in the first region and electrodes in the second region, impedances (Z3) measured between the electrodes in the first region, and the first Two-region electrode And calculating means for calculating the impedance (Z) of the human body by canceling the capacitive reactance component between the human body and each electrode by calculating the impedance (Z4) measured in To do.
According to the second invention, in the first invention, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are one of the first region. Impedance (Z1) measured between the electrode and one electrode of the second region, and impedance (Z2) measured between the other electrode of the first region and the other electrode of the second region ), And the computing means calculates the impedance (Z) of the human body,
Z = (1/2) {Z1 + Z2- (Z3 + Z4)}
The gist of the calculation is as follows.
In the third invention, in the first or second invention, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are the continuity of the human body. The gist is the impedance (Z1) between the electrodes far along the path and the impedance (Z2) between the electrodes close along the conduction path of the human body.
In the fourth invention, in the first or second invention, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are the continuity of the human body. An impedance (Z1) between the electrode of the first region located far from the second region along the path and the electrode of the second region located near the first region; and the human body The impedance (Z2) between the electrode of the first region located near the second region along the conduction path of the second region and the electrode of the second region located far from the first region. This is the gist.
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, on the seating surface on which a person is seated, each electrode of the first region is provided at a position corresponding to one thigh, and the second region The gist is that each electrode is provided at a position corresponding to the other thigh.
According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the impedance (Z) of the human body is periodically calculated by the computing means, and a change in the moisture content of the human body is determined based on a change in the value. The gist is to have a judging means for judging.
In the biological information measuring method according to the seventh aspect of the present invention, the first region and the second region set at positions separated along the conduction path through which a current flows through the human body is in contact with the human body directly or via an insulator, respectively. A biological information measurement method using two electrodes, two electrodes arranged in the direction of the conduction path in the first region and two electrodes arranged in the direction of the conduction path in the second region. Then, a selection step of selecting one set of electrodes from the combination of the four electrodes, an alternating current is supplied between the one set of electrodes selected by the selection step, and the impedance between the one set of electrodes is measured Impedance (Z1 and Z2) measured for two combinations of the measurement step, the electrode in the first region and the electrode in the second region, and the impedance (Z3) measured between the electrodes in the first region And the above And calculating the impedance (Z) of the human body by canceling the capacitive reactance component between the human body and each electrode by calculating the impedance (Z4) measured between the electrodes in the region. This is the gist.
According to an eighth aspect of the present invention, in the seventh aspect, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are one of the first region. Impedance (Z1) measured between the electrode and one electrode of the second region, and impedance (Z2) measured between the other electrode of the first region and the other electrode of the second region In the calculation step, the impedance (Z) of the human body is
Z = (1/2) {Z1 + Z2- (Z3 + Z4)}
The gist of the calculation is as follows.
In the ninth invention, in the seventh or eighth invention, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are the continuity of the human body. The gist is the impedance (Z1) between the electrodes far along the path and the impedance (Z2) between the electrodes close along the conduction path of the human body.
According to the tenth aspect of the present invention, in the seventh or eighth aspect, the impedances (Z1 and Z2) measured for two combinations of the electrode of the first region and the electrode of the second region are the continuity of the human body. An impedance (Z1) between the electrode of the first region located far from the second region along the path and the electrode of the second region located near the first region; and the human body The impedance (Z2) between the electrode of the first region located near the second region along the conduction path of the second region and the electrode of the second region located far from the first region. This is the gist.
In an eleventh aspect of the present invention, in any one of the seventh to tenth aspects, on the seating surface on which a person is seated, the first region is a position corresponding to one thigh, and the second region is on the other thigh. The gist is the corresponding position.
In a twelfth aspect of the present invention, in any one of the seventh to eleventh aspects, the impedance (Z) of the human body is periodically calculated by the calculation step, and a change in the moisture content of the human body is calculated based on a change in the value. The gist is to include a determination step of determining.

  The biological information measuring apparatus according to the first aspect of the present invention is in contact with a human body directly or through an insulator in a first region and a second region set at positions separated along a conduction path through which a current flows in the human body. A selection means for selecting one electrode from a combination of two electrodes arranged in the direction of the conduction path in the region, two electrodes arranged in the direction of the conduction path in the second region, and the four electrodes; Impedances (Z1 and Z1) measured for two combinations of measuring means for supplying an alternating current between selected electrodes and measuring the impedance between the electrodes, and an electrode in the first region and an electrode in the second region Z2), the impedance (Z3) measured between the electrodes in the first region, and the impedance (Z4) measured between the electrodes in the second region, thereby calculating the capacitance between the human body and each electrode. Reactive reactance Comprising calculating means for calculating a human body impedance (Z) to cancel the minutes, the. For this reason, even if an insulator such as clothing is interposed between each electrode and the skin of the target human body, the capacitive reactance component between each electrode and the human body is canceled to reduce only the impedance (Z) of the human body. Can be sought. As a result, it is not necessary to provide an electrode at a part that the human body directly touches, such as a steering wheel, and it is possible to measure biological information by providing an electrode on the seating surface of the seat.

The impedances (Z1 and Z2) measured for two sets of combinations of the first region electrode and the second region electrode are measured between one electrode of the first region and one electrode of the second region. Impedance (Z1) and impedance (Z2) measured between the other electrode of the first region and the other electrode of the second region, and the computing means calculates the impedance (Z) of the human body,
Z = (1/2) {Z1 + Z2- (Z3 + Z4)}
When calculating by the above, the impedance component (Z) between the first region and the second region can be easily obtained by subtracting the impedance component between each electrode and the skin and between the electrodes in each region. Can do.

The measured impedances (Z1 and Z2) are an impedance (Z1) between electrodes far along the conduction path of the human body and an impedance (Z2) between electrodes close to the conduction path of the human body. In this case, the impedance (Z) of the human body can be obtained more accurately.
In addition, the measured impedances (Z1 and Z2) are the values of the electrode of the first region located far from the second region along the conduction path of the human body and the second region located close to the first region. The impedance (Z1) between the electrodes and the electrodes of the first region that are close to the second region along the conduction path of the human body, and the electrodes of the second region that are far from the first region Even when the impedance is between (Z2), the impedance (Z) of the human body can be obtained more accurately.

  In the seating surface on which a person sits, each electrode in the first region is provided at a position corresponding to one thigh, and each electrode in the second region is provided at a position corresponding to the other thigh. On the other hand, the conduction path between the first region and the second region can be a relatively long distance, which is suitable for measuring the impedance of the human body. In addition, for example, it is possible to acquire the driver's biological information by using electrodes provided on the seat surface portion of the driver's seat of the vehicle.

  In the case where the calculation means includes a determination means for periodically calculating the impedance (Z) of the human body and determining a change in the moisture content of the human body based on the change in the value, It is possible to determine the moisture movement of the water. This makes it possible to assess the seated person's local edema and dehydration and alert the seated person.

Although the above describes the case where the present invention is realized as a biological information measuring device, the seventh to twelfth inventions are configured to realize a biological information measuring method corresponding to the above. Substantial actions and effects are the same as in the case of the biological information measuring device, and all the components of each invention relating to the biological information measuring device can be configured as a biological information measuring method.
The idea of the present invention is not limited to the biological information measuring device or the biological information measuring method, but includes various aspects. Therefore, the present invention can be realized as a program having the above-described means or steps as functions.

The present invention will be further described in the following detailed description with reference to the drawings referred to, with reference to non-limiting examples of exemplary embodiments according to the present invention. Similar parts are shown throughout the several figures.
It is a block diagram showing the structure of a biological information measuring device. It is a schematic diagram for demonstrating the component of the impedance produced between each electrode. This is an equivalent circuit when four electrodes (a to d) are arranged at the positions of the left and right thighs and the impedance between the two selected electrodes (b and c) is measured. FIG. 3 is a schematic diagram illustrating a conduction path and impedance components when measuring an impedance (Z1) between electrodes ad illustrated in FIG. 2. FIG. 3 is a schematic diagram illustrating a conduction path and impedance components when measuring an impedance (Z2) between electrodes bc illustrated in FIG. 2. FIG. 3 is a schematic diagram illustrating a conduction path and impedance components when measuring an impedance (Z3) between electrodes ab illustrated in FIG. 2. FIG. 3 is a schematic diagram illustrating a conduction path and impedance components when measuring an impedance (Z4) between electrodes cd illustrated in FIG. 2. It is a model perspective view showing the example which provides an electrode in the seat surface of a vehicle seat. It is a schematic diagram showing the example of a test which affixes an electrode to the leg part of one leg and measures impedance. It is a graph which shows a time-dependent change of the bioimpedance measured in a thigh and a lower leg.

Hereinafter, the present invention will be described in detail with reference to the drawings.
The items shown here are for illustrative purposes and exemplary embodiments of the present invention, and are the most effective and easy-to-understand explanations of the principles and conceptual features of the present invention. It is stated for the purpose of providing what seems to be. In this respect, it is not intended to illustrate the structural details of the present invention beyond what is necessary for a fundamental understanding of the present invention. It will be clear to those skilled in the art how it is actually implemented.

(Configuration of biological information measuring device)
The configuration of the biological information measuring apparatus according to this embodiment is shown in FIG. The biological information measuring apparatus 1 is in contact with the human body 8 directly or via an insulator in the first region 21 and the second region 22 set at positions separated along the conduction path 81 through which current flows in the human body 8, respectively. Four electrodes 3 are provided. The four electrodes 3 include two electrodes a (311) and b (312) arranged in the direction of the conduction path 81 in the first region 21, and two electrodes c arranged in the direction of the conduction path 81 in the second region 22. (321) and d (322). That is, the four electrodes 3 are arranged along the conduction path 81 in the order of abcd.
Moreover, the biological information measuring device 1 supplies an alternating current between a selection unit 4 that selects one set of electrodes from a combination of four electrodes a to d, and a set of electrodes selected by the selection unit 4, Measuring means 5 for measuring the impedance between a pair of electrodes is provided.

Furthermore, the biological information measuring apparatus 1 includes a calculation unit 6 that calculates the impedance (Z) of the human body 8 using the selection unit 4 and the measurement unit 5. The calculation means 6 is measured for two combinations (for example, ad and bc) of the combinations of the electrodes (a and b) in the first region 21 and the electrodes (c and d) in the second region 22, respectively. Impedance (Z1 and Z2) can be obtained. Moreover, the impedance (Z3) measured between the electrodes ab in the first region 21 can be acquired. Furthermore, the impedance (Z4) measured between the electrodes cd in the second region 22 can be acquired. Then, by calculating the acquired impedance value, the capacitive reactance component between the human body 8 and each electrode 3 is canceled, and the impedance (Z) of the human body 8 is calculated.
Here, the calculated impedance (Z) of the human body 8 includes the electrode b in the first region 21 located near the second region 22 along the conduction path 81 of the human body, and the first location located near the first region 21. The impedance between the two regions 22 and the electrode c can be set. The impedance of the human body is also called “biological impedance”.

The conduction path 81 is intended to be a path through which a current flows in the human body 8 when an electrical signal is applied from an electrode between two regions of the human body 8.
The first area 21 and the second area 22 can be set at arbitrary positions on the human body 8. The first region 21 and the second region 22 are preferably set so that the conduction path 81 of the human body 8 is as long as possible. For example, the first region 21 and the second region 22 are respectively left and right thighs, left and right palms, left and right soles, upper and lower back portions, left and right portions, and the like. Can do.

Each electrode 3 may be provided so as to be in contact with the human body 8 via an insulator such as cloth or clothing. Moreover, you may touch the skin of the human body 8 directly.
Two electrodes 3 are provided separately in each of the regions 21 and 22. Each electrode adjacent in one region (21 or 22) is arranged such that the length of the conduction path 81 is different from the other region (22 or 21). That is, as shown in FIG. 1, the electrode a in the first region 21 is arranged so that the distance from the second region 22 is farther than the electrode b, and the electrode d in the second region 22 is arranged in the first region 21. From the electrode c.
The size and shape of each electrode 3 are not particularly limited. The gap between adjacent electrodes in one region is preferably longer than the thickness of an insulator or the like interposed between the electrode and the human body, and can be, for example, 5 mm or more.

The material of the electrode 3 is not limited as long as it has conductivity, and for example, a metal such as a flat plate, a net-like body, or a cloth-like body can be used. Further, it may be a woven fabric woven with metal, carbon or the like, or a knitted fabric (conductive fabric) woven with conductive yarn. When each electrode 3 is provided in a seat, the electrode 3 may be provided on the surface of a seat or the like with which a human body is in contact, or may be provided on the back of a skin material.
When a conductive cloth is used as the electrode 3, the electrode can be formed so as to constitute a surface material such as a seat with which a human body contacts, and this is preferable without impairing the design and comfort. Examples of the conductive cloth include a woven cloth in which conductive fibers such as stainless steel wires, carbon fibers, and plating fibers are appropriately woven. Furthermore, a knitted fabric appropriately knitted with conductive yarn such as yarn entangled with a stainless steel wire, yarn dispersed with metal or carbon, yarn coated with resin containing a conductive substance, and the like can be given.

  The selection means 4 is configured to select one set of electrodes by switching from six combinations of the four electrodes 3 and to electrically connect each selected electrode to the measurement means 5. The selection of one set of electrodes can be configured to be performed by an instruction from the calculation means 6. For specific connection switching, a known switching method can be applied.

The measuring means 5 is means for supplying an alternating current between the pair of electrodes selected by the selecting means 4 and measuring the impedance between the pair of electrodes. For this reason, the measuring means 5 can be configured to include an alternating current source 51, a current measuring unit 52 connected in series to the electrodes, a voltage measuring unit 53 connected in parallel to both electrodes, and the like.
The current supplied from the alternating current source 51 to the human body 8 via the electrode 3 is preferably a current of 0.5 mA or less, which is assumed to prevent the human body from sensing energization, for safety to the human body. The frequency of the current supplied from the AC current source 51 may be a single frequency in the range of about 1 kHz to 10 MHz, a combination of two or more frequencies, or a frequency (period) sweep of the band depending on the measurement purpose. it can. For example, bioimpedance can be measured by using a 50 kHz sine wave at a single frequency.
The current measurement unit 52 and the voltage measurement unit 53 measure the current and voltage (effective value) between a pair of electrodes. The measuring means 5 or the calculating means 6 can obtain the impedance between the electrodes based on this measured value by a known method, and can use it as the measured impedance. The measured value is sent from the measuring means 5 to the calculating means 6.

The calculation means 6 is means for calculating the impedance (Z) of the human body 8 using the selection means 4 and the measurement means 5. In order to calculate the impedance (Z) of the human body 8 at a certain time, the calculation means 6 acquires at least four measurement values. First, one (for example, ad) of the combinations of the electrodes in the first region 21 and the second region 22 is selected, and the impedance (Z1) between the electrodes is acquired. Secondly, another one (for example, cb) of the combination of the electrode of the first region 21 and the electrode of the second region 22 is selected, and the impedance (Z2) between the electrodes is acquired. Third, the impedance (Z3) measured between the electrodes (ab) in the first region 21 is acquired. Fourth, the impedance (Z4) measured between the electrodes (cd) in the second region 22 is acquired.
The impedances (Z1 to Z4) may be acquired in any order. For this reason, the calculating means 6 can be configured to select a predetermined combination of electrodes in order by the selecting means 4 and obtain a measurement value between the electrodes from the measuring means 5. A method for calculating the impedance (Z) of the human body 8 based on each measurement value will be described later.

  Furthermore, the biological information measuring apparatus 1 calculates the impedance (Z) of the human body 8 periodically by the calculating means 6 and uses the judging means 7 for judging the local water content change of the human body 8 based on the change of the value. Can be provided (not shown). As will be described later, the present inventor is a useful index that reflects the subjective fatigue of the seated person when the person sits in the seat for a long time, and the bioelectrical impedance changes with time in each part of the human body. I found. The determination means 7 measures the impedance (Z) of the human body 8 at regular intervals from the time of sitting, and changes in the local water content of the human body 8 (for example, occurrence of edema) from the value, direction of change, inclination, etc. Configured to determine. Moreover, it can also comprise so that a seated person's fatigue feeling may be estimated based on the change of the local moisture content.

Specific configuration methods such as control and calculation in each of the above means are not particularly limited, and can be configured using, for example, a logic circuit, a memory, a microprocessor, or the like. Moreover, each means which comprises the biometric information measuring device 1 can be comprised as a biometric information measuring method provided with the process corresponded to each. Furthermore, it can also be configured as a biological information measurement program having a function corresponding to each means.
Moreover, this biological information measuring device may be configured as a biological impedance measuring device, or various biological information measuring devices (for example, measuring devices for lean body mass, obesity, muscle mass, etc.) that use measurement of biological impedance. It may be configured as part.

(Measurement method using biological information measuring device)
Below, the measurement method of the bioelectrical impedance in the biometric information measuring device 1 is demonstrated by making into an example the case where the left thigh (back side) of the human body is the first region and the right thigh (back side) is the second region. To do.
FIG. 2 is a diagram schematically showing the electrode arrangement and the measured impedance component in the above case when viewed from the back side of the human body 8. The configuration of the electrode 3 is the same as in FIG. 1, and the electrodes a and b are arranged on the left thigh 82 and the electrodes c and d are arranged on the right thigh 83. Here, the impedance of the human body (conduction path 81) between the electrodes bc, between the electrodes ab, and between the electrodes cd is expressed as Z (Zbc), Zab, and Zcd, respectively. Further, when each electrode is in contact with the human body via an insulator 95 made of cloth or the like, a capacitive reactance is generated between each electrode and the human body. Capacitive reactances generated between the electrodes a, b, c and d and the human body are represented as Xa, Xb, Xc and Xd, respectively.

  Conventionally, a four-electrode method for measuring impedance using four electrodes is known. In the four-electrode method, an alternating current is supplied between the electrodes ad shown in FIG. 2, and a voltage is measured between the electrodes bc. However, in that case, since the impedance to be measured is (Z + Xb + Xc), the impedance (Z) of the human body 8 cannot be correctly measured under the condition that the capacitive reactance cannot be ignored. The measurement by the biological information measuring device 1 aims to accurately measure the impedance (Z) of the human body 8 even when the capacitive reactance is large.

For this reason, the biological information measuring apparatus 1 supplies an alternating current between two electrodes selected from the electrodes a to d and measures a voltage (voltage drop) between the electrodes (two-electrode method). FIG. 3 is an equivalent electric circuit diagram when the electrodes b and c are selected as one set. The same applies when other electrodes are selected as one set. In FIG. 3, the impedance (Z) of the human body 8 between the electrodes bc is represented by the electrostatic capacitance Cm of the cell membrane, the resistance Ri of the intracellular fluid, and the resistance Ro of the extracellular fluid. In addition, capacitive reactances Xb and Xc are generated between the electrodes b and c and the human body 8 due to the cloth or the like. Then, the impedance measured from the current A applied from the AC current source 51 and the voltage V detected via the shunt resistor Rs sufficiently larger than the contact impedance is (Z + Xb + Xc).
The impedance (Zad) when the electrodes a and d are selected as one set is the impedance (Zab) of the human body 8 between the electrodes bc and the impedance (Zab) of the conduction path 81 between the electrodes ab and between the electrodes cd. And Zcd) are added, and capacitive reactances Xa and Xd between the electrodes a and d and the human body 8 are generated, so that (Z + Zab + Zcd + Xa + Xd) is obtained (see FIG. 2).

The biological information measuring apparatus 1 performs, for example, the following four types of impedance measurement.
As shown in FIG. 4, the impedance (Z1) between the electrodes ad is measured.
Z1 = (Z + Zab + Zcd + Xa + Xd)
As shown in FIG. 5, the impedance (Z2) between the electrodes bc is measured.
Z2 = (Z + Xb + Xc)
As shown in FIG. 6, the impedance (Z3) between the electrodes ab is measured.
Z3 = (Zab + Xa + Xb)
As shown in FIG. 7, the impedance (Z4) between the electrodes cd is measured.
Z4 = (Zcd + Xc + Xd)

The biological information measuring apparatus 1 performs the following calculation using each impedance (Z1 to Z4) measured as described above.
(Z1 + Z2)-(Z3 + Z4)
If the measured impedances (Z1 to Z4) are applied to this equation, the capacitive reactance component (Xa, Xb, Xc, Xd) and the impedance (Zab) of the conduction path 81 between the electrodes ab and between the electrodes cd. , Zcd) is erased and 2Z is obtained. That is, a value twice the impedance (Z) of only the human body 8 between the electrodes bc can be obtained.
Instead of the impedance measurement between the electrodes ad and between the electrodes bc (Z1 and Z2), the impedance between the electrodes ac is measured and the measured value is set as Z1, the impedance between the electrodes bd is measured and the measured value is set as Z2. Then,
Z1 = (Z + Zab + Xa + Xc)
Z2 = (Z + Zcd + Xb + Xd)
It becomes. Again,
(Z1 + Z2)-(Z3 + Z4) = 2Z
Therefore, as described above, the impedance (Z) value of only the human body 8 between the electrodes bc can be obtained.
There is no particular limitation on the number of times and the period for measuring such impedance.

FIG. 8 shows an example in which the biological information measuring device 1 is applied to a vehicle seat. Four electrodes a to d (311, 312, 321, 322) are provided on the seating surface 91 of the seat 9 so as to correspond to the left thigh 82 and the right thigh 83 of the seated person 8. A test example using this biological information measuring apparatus 1 will be described.
The electrodes a to d were metal foils each having a size of 50 × 100 mm, and a gap of 20 mm was provided between the electrodes a and b and between the electrodes c and d. Then, in a state where a seated occupant (adult male) 8 is seated, the impedances (Z1 to Z4) are measured by an alternating current of 50 kHz and 0.4 mA.

  The measurement results were as follows: Z1 = 7278Ω, Z2 = 7335Ω, Z3 = 7231Ω, Z4 = 7219Ω, and Z = (1/2) {Z1 + Z2− (Z3 + Z4)} = 80Ω. On the other hand, when an electrode of the same size was directly attached to the skin of the seated person 8 at the position of the electrodes b and c, and the impedance between the two electrodes was measured with the same alternating current as described above, it was 75Ω. When the impedance of the human body is obtained by the biological information measuring apparatus 1 in the state where the clothes are interposed, the same value is obtained when the impedance of the human body is measured by directly applying electrodes to the skin. It was confirmed that bioimpedance can be measured correctly.

Furthermore, with the electrodes attached to the left and right thighs of the seated person as described above, bioimpedance was measured every minute for about 120 minutes. At the same time, as shown in FIG. 9, electrodes were also attached to two places (under the knee and above the heel) of the lower leg of one leg, and the bioimpedance was measured. The lower leg was also measured with the same alternating current as the measurement between the left and right thighs. The measurement results are shown in FIG.
As shown in FIG. 10, in the thigh, the impedance value increased with time. On the other hand, in the lower leg, the impedance decreased with time. This is thought to be due to the fact that moisture moves below the foot and the impedance of the thigh where moisture has decreased increases, while edema occurs in the lower leg and impedance decreases.

  Based on the above results, this biometric information measurement method measures bioimpedance at an appropriate period from the initial state, and determines the local moisture content change by detecting its value, direction of change, inclination, etc. You can see that you can. Changes in the amount of water in the human body due to edema etc. can be associated with the subjective fatigue of the seated person, so using the measurement results of this biological information measurement method, alert the seated person, It is possible to issue a warning.

  It should be noted that the above description is for illustrative purposes only and is not to be construed as limiting the invention. Although the invention has been described with reference to exemplary embodiments, it is to be understood that the language used in the description and illustration of the invention is illustrative and exemplary rather than restrictive. As detailed herein, modifications may be made in the embodiments within the scope of the appended claims without departing from the scope or spirit of the invention. Although specific structures, materials, and embodiments have been referred to in the detailed description of the invention herein, it is not intended to limit the invention to the disclosure herein, but rather, the invention is claimed. It shall cover all functionally equivalent structures, methods and uses within the scope.

  DESCRIPTION OF SYMBOLS 1; Biological information measuring device, 21; 1st area | region, 22; 2nd area | region, 3; Electrode, 311; Electrode a, 312; Electrode b, 321; Electrode c, 322; Electrode d, 4; Measuring means 51; AC current source 52; Current measuring section 53; Voltage measuring section 6; Arithmetic means 7; Judging means 8; Human body 81; Conduction path 9; Seat 91;

Claims (12)

Four electrodes in contact with the human body directly or through an insulator in the first region and the second region set at positions separated along a conduction path through which a current flows in the human body, respectively, And two electrodes arranged in the direction of the conduction path, and two electrodes arranged in the direction of the conduction path in the second region,
A selection means for selecting one set of electrodes from a combination of the four electrodes;
Measuring means for supplying an alternating current between a pair of electrodes selected by the selecting means and measuring impedance between the electrodes;
Impedances (Z1 and Z2) measured for two combinations of electrodes in the first region and electrodes in the second region, impedances (Z3) measured between the electrodes in the first region, and the first Calculating means for calculating the impedance (Z) of the human body by canceling the capacitive reactance component between the human body and each electrode by calculating the impedance (Z4) measured between the electrodes of the two regions;
A biological information measuring device comprising: Impedances (Z1 and Z2) measured for two sets of combinations of the first region electrode and the second region electrode are obtained by comparing one electrode of the first region and one electrode of the second region. Impedance (Z1) measured between the other electrode of the first region and the other electrode of the second region (Z2),
The computing means calculates the impedance (Z) of the human body,
Z = (1/2) {Z1 + Z2- (Z3 + Z4)}
The biological information measuring device according to claim 1, which is calculated by:   Impedances (Z1 and Z2) measured for two sets of combinations of the electrodes in the first region and the electrodes in the second region are impedances (Z1) between electrodes far from each other along the conduction path of the human body, The biological information measuring device according to claim 1, wherein the biological information measuring device is an impedance (Z2) between electrodes close to each other along a conduction path of the human body.   Impedances (Z1 and Z2) measured for two sets of combinations of the first region electrode and the second region electrode are located far from the second region along the conduction path of the human body. Impedance (Z1) between the electrode in the first region and the electrode in the second region located close to the first region, and the position close to the second region along the conduction path of the human body The living body information measuring device according to claim 1 or 2 which is impedance (Z2) between the electrode of said 1st field and said electrode of said 2nd field in a position far from said 1st field.   5. The electrode of the first region is provided at a position corresponding to one of the thighs, and each electrode of the second region is provided at a position corresponding to the other thighs on a seating surface on which a person is seated. The biological information measuring device according to any one of the above.   The living body according to claim 1, further comprising a determination unit that periodically calculates the impedance (Z) of the human body by the calculation unit and determines a change in the moisture content of the human body based on a change in the value. Information measuring device. Four electrodes in contact with the human body directly or through an insulator in the first region and the second region set at positions separated along a conduction path through which a current flows in the human body, respectively, A biological information measurement method using two electrodes arranged in the direction of the conduction path and two electrodes arranged in the direction of the conduction path in the second region,
A selection step of selecting a set of electrodes from the combination of the four electrodes;
A measuring step of supplying an alternating current between the set of electrodes selected by the selection step and measuring an impedance between the set of electrodes;
Impedances (Z1 and Z2) measured for two combinations of electrodes in the first region and electrodes in the second region, impedances (Z3) measured between the electrodes in the first region, and the first A calculation step of calculating the impedance (Z) of the human body by canceling the capacitive reactance component between the human body and each electrode by calculating the impedance (Z4) measured between the electrodes of the two regions;
A biological information measuring method comprising: Impedances (Z1 and Z2) measured for two sets of combinations of the first region electrode and the second region electrode are obtained by comparing one electrode of the first region and one electrode of the second region. Impedance (Z1) measured between the other electrode of the first region and the other electrode of the second region (Z2),
In the calculation step, the impedance (Z) of the human body is
Z = (1/2) {Z1 + Z2- (Z3 + Z4)}
The biological information measuring method according to claim 7, which is calculated by:   Impedances (Z1 and Z2) measured for two sets of combinations of the electrodes in the first region and the electrodes in the second region are impedances (Z1) between electrodes far from each other along the conduction path of the human body, The biological information measuring method according to claim 7 or 8, which is an impedance (Z2) between electrodes close to each other along a conduction path of the human body.   Impedances (Z1 and Z2) measured for two sets of combinations of the first region electrode and the second region electrode are located far from the second region along the conduction path of the human body. Impedance (Z1) between the electrode in the first region and the electrode in the second region located close to the first region, and the position close to the second region along the conduction path of the human body The biological information measuring method according to claim 7 or 8, which is an impedance (Z2) between an electrode in the first area and an electrode in the second area located far from the first area.   The biological information according to any one of claims 7 to 10, wherein, on a seating surface on which a person is seated, the first region is a position corresponding to one thigh and the second region is a position corresponding to the other thigh. Measurement method.   The living body according to claim 7, further comprising a determination step of periodically calculating the impedance (Z) of the human body through the calculation step and determining a change in the moisture content of the human body based on a change in the value. Information measurement method.

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