JP2001276008A - Instrument and method for measuring adipocyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instrument for measuring adipocyte, by which the size of the adipocyte as an index for recognizing a health state is calculated by utilizing a biological electric impedance method. SOLUTION: The instrument 100 is provided with a measuring signal generator 72, etc., for generating a measuring signal Ia, an I/V converter 91, etc., for measuring currents flowing when the generated measuring signal Ia is thrown into fat in the abdominal part of a subject, a differential amplifier 81, etc., for measuring a potential difference generated in fat in the abdominal part of the subject and a CPU 3 for calculating a biological electric impedance or an admittance from Vc and Vp measured by the converter 91 and the amplifier 81. The CPU 3 calculates the size of the adipocyte based on the calculated biological electric impedance or the admittance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adipocyte measuring apparatus, and more particularly, to an adipocyte measuring apparatus and an adipocyte measuring method for calculating the size of adipocytes between predetermined parts of a subject by using a bioelectric impedance method. About.

[0002]

2. Description of the Related Art The inventor of the present invention has previously applied for an apparatus using an M-sequence signal as a bioelectrical impedance measuring apparatus (Japanese Patent Laid-Open No. 10-14898). In the invention, by performing a Fourier transform on the four-terminal A / D-converted signal, bioelectric impedance at many frequencies is measured to calculate information on the water content inside and outside the cell. Although not described in the specification, this apparatus outputs an M-sequence signal many times and performs synchronous addition of each signal in order to improve the SN ratio of the signal.

[0003] The prior art will be described below. 2. Description of the Related Art In recent years, research on the electrical characteristics of living organisms has been conducted for the purpose of evaluating the body composition of humans and animals. The electrical characteristics of living organisms vary significantly depending on the type of tissue or organ. For example, in the case of humans, the electrical resistivity of blood is around 150 Ω · cm, whereas the electrical resistivity of bone and fat is 1 to 5 kΩ · cm. The electrical characteristics of the living body are called bioelectric impedance, and are measured by passing a small current between a plurality of electrodes attached to the body surface of the living body. The method of estimating the body water distribution, body fat percentage, and body fat mass of the subject from the bioelectric impedance obtained in this way is called bioelectric impedance method ("Bioelectric impedance method as a method for evaluating body composition", Baumgartner RN, etc., `` Bioelectric impedance and its clinical application '', Medical Electronics and Biotechnology, Hiroshi Kanai, 20 (3) Jun 1982, `` Estimation of body limb water distribution by impedance method and its application '', Medical electronics and biotechnology, Makoto Haeno et al., 23 (6) 1985, "Long-term measurement of urinary bladder volume by impedance method", Ergonomics, Yasuo Kuchimachi, 28 (3) 1992, etc.) .

[0004] Bioelectric impedance is derived from the resistance of a living body to the current carried by ions in the body (resistance) and the reactance associated with various types of polarization processes created by cell membranes, tissue interfaces, or non-ionized tissue. Be composed. Capacitance, which is the reciprocal of reactance, causes a time delay in current rather than voltage, and creates a phase shift (phase shift). This value is the arctangent of the ratio of reactance to resistance (arctangent). It can be determined geometrically as a phase angle.

The bioelectric impedance Z, the resistance R, the reactance X and the electric phase angle φ depend on the frequency. At very low frequencies f _L , the bioelectrical impedance Z at the cell membrane-tissue interface is too high to conduct electricity. Thus, electricity flows only through the extracellular fluid and the measured bioelectrical impedance Z is purely a resistance R.

Next, as the frequency increases, the current penetrates the cell membrane, the reactance X increases, and the phase angle φ increases. The magnitude of the bioelectrical impedance Z is equal to the value of the vector defined by Z ² = R ² + X ² . The frequency at which both the reactance X and the phase angle φ are maximized is called a critical frequency f _C , which is one electrical characteristic value of a living body that is a conductive conductor. Beyond this critical frequency f _C , the cell membrane-tissue interface loses its capacitive capacity, and the reactance X decreases accordingly. At very high frequencies f _H , the bioelectrical impedance Z is again purely equivalent to the resistance R.

FIG. 10 is an electrical equivalent circuit diagram (equivalent circuit model) of the human body. In this figure, Cmk (k is an integer) represents cell membrane capacity, and Rik and Re represent intracellular fluid resistance and extracellular fluid resistance, respectively. Low frequency f
_{In L} , the current mainly flows through the extracellular space, and the impedance Z becomes equal to the extracellular fluid resistance Re. At high frequencies f _H , the current passes completely through the cell membrane, and the cell membrane capacitance Cm is substantially equivalent to being short-circuited. Therefore, the impedance Z at the high frequency f _H is equal to the combined resistance Ri · Re / (Ri +
Re), (1 / Ri = Σ1 / Rik).

According to the method described above, the intracellular fluid resistance R
i and extracellular fluid resistance Re can be obtained, and based on these, the lean body mass of the subject can be estimated, and a change in body water distribution can be estimated based on a change in these resistances Re and Ri. As a bioelectrical impedance measuring device that performs measurement / estimation of each of these parameters by injecting a small sine wave current of a plurality of frequencies arbitrarily selected into a living body and digitally processing the obtained signal, there is a special table. 6-5
The thing described in 06854 is known.

On the other hand, a device for calculating body fat, such as a health management guideline advice device disclosed in Japanese Patent Application Laid-Open No. 11-113871, has been widely used in ordinary households.
This device calculates the weight of tissue excluding body fat and calculates the body fat percentage.

[0010]

The body fat percentage can be said to be a good index from a cosmetic point of view, but is not necessarily a good index from a health point of view. This is because, among body fats, subcutaneous fat has relatively little harm to health, and visceral fat has relatively great harm to health. However, when actually calculating the body fat percentage, since both subcutaneous fat and visceral fat are collectively measured,
It is hard to be a good indicator of health.

On the other hand, fat cells not only store energy but also prevent PAI1 from forming thrombus.
It is known to emit substances called. Since this substance is secreted in large amounts when fat cells are enlarged, it is considered that the size of fat cells can be an important index for evaluating a health condition. An object of the present invention is to provide a fat cell measuring apparatus and a fat cell capable of calculating the size of a fat cell between predetermined portions of a subject in a relatively simple configuration and non-invasively using a bioelectric impedance method. It is to provide a measuring method.

[0012]

A fat cell measuring apparatus according to the present invention comprises a signal generating means for generating a measuring signal, and a current measuring means for measuring a current flowing when the generated measuring signal is applied between predetermined portions of a subject. Means, a voltage measuring means for measuring a potential difference generated between predetermined parts of the subject, and a bioelectric impedance or admittance from the current value measured by the current measuring means and the voltage value measured by the voltage measuring means. Calculating means for calculating the size of the fat cell based on the calculated bioelectrical impedance or admittance.

Further, the calculating means calculates the size of the fat cell based on the impedance or admittance at a specific frequency, thereby calculating the size of the fat cell at a small number or a single frequency. Therefore, the device can be manufactured relatively inexpensively. Further, the calculating means calculates the size of the fat cell based on the frequency at which the absolute value of the imaginary part of the impedance or admittance is the maximum, so that the fat cell is measured regardless of the thickness of the fat to be measured. The size can be calculated.

The calculating means calculates the size of the fat cell based on the average frequency of two real parts of impedance or admittance in which the imaginary part of impedance or admittance is 0. The size of fat cells can be calculated regardless of the thickness of fat to be measured. Further, the calculating means calculates the size of the fat cell based on the impedance or admittance and the thickness of the fat, thereby performing the fat thickness correction of the impedance. The size of fat cells can be calculated in consideration of the influence of the size.

In another aspect, the method for measuring fat cells of the present invention includes a signal generating step of generating a measurement signal, and a current measuring step of measuring a current flowing when the generated measurement signal is applied between predetermined portions of a subject. A voltage measuring step of measuring a potential difference generated between predetermined portions of the subject, and calculating a bioelectric impedance or an admittance from the current value measured by the current measuring step and the voltage value measured by the voltage measuring step. And calculating the size of the fat cell based on the calculated bioelectrical impedance or admittance.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an electrical configuration of the fat cell measuring device according to the embodiment of the present invention. The present fat cell measuring device has a keyboard 1
And a measurement processing unit 2 that sends a probe current Ia as a measurement signal to the body of the subject (see FIG. 2), thereby digitally processing voltage / current information obtained from the subject, and controls each unit of the device, and a measurement processing unit. CPU (Central Processing Unit) 3 for calculating various physical quantities such as bioelectric impedance between predetermined parts of the human body and the size of fat cells based on the processing results of 2, and various physical quantities of the subject's body calculated by the CPU 3 And a variety of data (eg, height, gender, extracellular fluid, intracellular fluid, etc. of the subject)
, A RAM 5 in which a work area of the CPU 3 is set, and a ROM 6 in which a processing program of the CPU 3 is fixedly stored.

The keyboard 1 includes a measurement start switch for the measurer to instruct the start of measurement, input of human body characteristic items such as height, gender and age of the subject, total measurement time T and measurement interval t according to the measurement purpose. It consists of various keys for setting / setting change. Operation data of each key supplied from the keyboard 1 is converted into a key code by a key code generation circuit (not shown) and supplied to the CPU 3.

The measurement processing section 2 includes a PIO (parallel interface) 71, a measurement signal generator 72, a low-pass filter (hereinafter, referred to as LPF) 73, coupling capacitors 74, 80a, 80b, 90, a differential amplifier 81,
/ V converter (current / voltage converter) 91, LPFs 82 and 92 composed of analog anti-aliasing filters, A
/ D converters 83 and 93 and sampling memories (ring buffers) 84 and 94 are provided.

The measurement signal generator 72 has an output resistance of 10 kΩ or more over the entire range of the signal frequency to be generated, and the PIO 71 has a predetermined period t during the entire measurement time T.
Each time a signal generation instruction signal is supplied from the CPU 3 via the CPU 3, the probe current Ia of the longest linear code (maximal linear codes) sequence (M sequence) is repeatedly generated a predetermined number of times.

The LPF 73 generates the probe current I
a (measurement signal) high-frequency noise is removed. The coupling capacitor 74 removes the DC component included in the probe current Ia from the LPF 73 and sends it to the electrode A (see FIG. 2) so that the DC component does not flow through the body of the subject. The probe current Ia is supplied to the electrode A via a terminal Hc and a measurement cable 7 such as a double shielded wire.

The supply period of the signal generation instruction signal coincides with the measurement interval t set by the operator using the keyboard 1. Furthermore, in this example, the probe current (measurement signal)
The number of repetitions of Ia is 1 to 1 per signal generation instruction signal.
256 times. The number of repetitions is also measured by keyboard 1
May be set arbitrarily by using. The number of repetitions increases as the number of repetitions increases. However, although it is a minute current, it may adversely affect the human body when continuously applied to the human body for a long time. Therefore, the number of repetitions is preferably 1 to 256.

Here, the M-sequence signal will be described. The M-sequence signal is a code signal generally used in a spread-spectrum communication system or a spread-spectrum ranging system, and is the longest of the code sequences generated by a shift register or a delay element having a certain length. Say. A binary M-sequence generator that generates an M-sequence signal having a length of (2 ⁿ -1) bits (n is a positive integer) is composed of an n-stage shift register and a logical combination of the n-stage states. And a logic circuit (exclusive logic circuit) that feeds back to the input of the shift register. The output of the M-sequence generator and the state of each stage at a certain sample time (clock time) are functions of the output of the feedback stage at the immediately preceding sample time. In the present embodiment, the shift register uses an eight-stage (n = 8) M-sequence generator, and the frequency of the shift clock of the shift register is set to approximately 20 MHz.

Next, the probe current Ia is
The signal is input to the electrode B after passing between predetermined portions of the subject (see FIG. 2). The probe current Ia is input to the terminal Lc via a measurement cable 8 such as a double shielded wire. The differential amplifier 81 includes coupling capacitors 80a, 80
b, the voltage (potential difference) between the two terminals Hc and Lc
Is detected. The differential amplifier 81 is connected to the probe current Ia.
Is applied between predetermined portions of the subject, a voltage Vp between the predetermined portions of the subject is detected, and the detected voltage Vp is supplied to the LPF 8.
Send to 2. This voltage Vp is a voltage drop due to bioelectric impedance between predetermined parts of the subject.

The LPF 82 removes high frequency noise from the voltage Vp and supplies it to the A / D converter 83. LPF
The cutoff frequency 82 is lower than half the sampling frequency of the A / D converter 83. As a result, aliasing noise that may occur in the A / D conversion processing by the A / D converter 83 is removed.

The A / D converter 83 converts the noise-eliminated voltage Vp into a digital signal at a predetermined sampling cycle every time the digital conversion signal Sd is supplied from the CPU 3, and converts the digitized voltage Vp Is supplied to the sampling memory 84 every sampling period. As described above, the electrode B and the coupling capacitor 90 are connected by the terminal Lc and the measurement cable 8 which is a double shielded wire. The coupling capacitor 90 is connected to the electrode B
The DC component included in the probe current Ia is removed and sent to the I / V converter 91.

The I / V converter 91 converts a current flowing between the electrodes A and B into a voltage. When the probe current Ia is applied between predetermined portions of the subject's body, the I / V converter 91
The probe current Ia flowing between predetermined portions of the subject
c and sends it to the LPF 92. The LPF 92 removes high frequency noise from the input voltage Vc, and
It is supplied to the converter 93. The cutoff frequency of the LPF 92 is lower than half the sampling frequency of the A / D converter 93. As a result, aliasing noise that may occur in the A / D conversion processing by the A / D converter 93 is removed.

The A / D converter 93 converts the noise-free voltage Vc into a digital signal at a predetermined sampling cycle every time the digital conversion signal Sd is supplied from the CPU 3, and converts the digitized voltage Vc Is supplied to the sampling memory 94 every sampling period. CPU3
Controls the operation of the entire fat cell measuring device according to the processing program stored in the ROM 6. The CPU 3 starts the measurement by the measurement processing unit 2 and stops the measurement after sampling the voltages Vp and Vc a predetermined number of times at a predetermined sampling cycle.

The CPU 3 first sets the sampling memory 8
4,94, stored as a function of time
The voltages Vp (f) and Vc (f), which are functions of frequency, are sequentially read out and subjected to Fourier transform processing.
(F is frequency), and then these are averaged.
Bioelectric impedance Z (f) ｛= Vp for each frequency
(F) / Vc (f)} is calculated, and the size of the fat cell is calculated. Next, the outline of the calculation of the size of the fat cell according to the present invention and the relationship between the bioelectric impedance and the size of the fat cell will be described with reference to FIGS.

FIG. 2 is a diagram schematically illustrating a state of use of the fat cell measuring device according to the present embodiment. FIG.
Illustrates a case where the size of abdominal fat cells is calculated by picking the skin of the abdomen as a predetermined part of the subject, and a caliper 9 is used as a means for sandwiching abdominal fat. The main scale 10 and the vernier 11 of the caliper 9 have electrodes A,
B is provided, and the fat in the abdomen is sandwiched between the electrodes A and B from above and below. When sandwiching fat, it is desirable to sandwich so as not to crush.

As described above, the coupling capacitor 7
4 (see FIG. 1) is input to the electrode A by the measuring cable 7 from the terminal Hc. The probe current Ia input to the electrode A flows through the abdomen of the subject sandwiched between the electrodes A and B, and is output from the electrode B. At this time, the probe current Ia flows through fat in the abdomen of the subject.

The probe current Ia from the electrode B is input to the coupling capacitor 90 via the measuring cable 8 via the terminal Lc. Thus, current / voltage conversion is performed by the above-described I / V converter 91. Also, terminal H
The voltage between the electrodes A and B (potential difference) between c and the terminal Lc
And this potential difference is caused by the differential amplifier 81 described above.
Is detected by

FIG. 3 is a diagram for explaining the relationship between the electrodes A and B and fat interposed between the electrodes in the measurement shown in FIG. FIG. 3 shows a state in which abdominal fat is contained in a predetermined shape defined by the surface area S of the electrodes A and B and the electrode interval d. This creates a unique capacitance between the electrodes A and B that is related to the fat of the subject. Adipocytes do not increase in number and grow in size after adulthood. The present fat cell measurement device calculates the bioelectric impedance and calculates the size of the fat cell using the bioelectric impedance, thereby providing an index for evaluating the health condition.

FIG. 4 is a diagram showing an electrical equivalent circuit of fat shown in FIG. The circuit diagram shown in FIG. 4 relates to a whole fat having a predetermined shape sandwiched between the electrodes A and B, and is constituted by an extracellular fluid resistance Re, an intracellular fluid resistance Ri, a cell membrane resistance Rm, and a cell membrane capacitance Cm. Indicates that you can see it.

The cell membrane resistance Rm of fat is generally sufficiently higher than the intracellular fluid resistance Ri. However, the cell membrane is a capacitor through which high-frequency current can pass. When fat enlarges, the number of fats per unit volume decreases, the cell membrane also becomes thin so as to expand the balloon, the cell membrane capacity Cm increases, and the cell membrane resistance Rm decreases.

When the bioelectrical impedance of a predetermined shape is expressed by an equation, Z (ω) = Re (Ri + Rm + j · Ri · Cm · Rm · ω)
/ (Re + Ri + Rm + j (Re + Ri) Rm ・ Cm ・
ω). Here, in the angular frequency ω → 0, the above equation _{Z (ω) → R O ≡Re} (Ri + Rm) / (Re + Ri +
Rm), and at the angular frequency ω → ∞, the above equation becomes Z (ω) → Rinf≡Re · Ri / (Re + Ri).

The critical frequency f _C is expressed as f _C = (Re + Ri + Rm) / (Re + Ri) × (1 /
2π) / (Rm · Cm). Cell membrane resistance Rm is, intracellular fluid resistance Ri, if sufficiently large compared to the extracellular fluid resistance Re, the frequency 0 R _O = Re, at infinite frequency is Rinf = Re · Ri (Re + Ri) critical frequency is f _C = (1 / 2π) / Cm (Re + Ri).

[0037] Thus, the adipocytes enlarged (the cell membrane capacitance Cm becomes larger), the critical frequency f _C is reduced, the fat cells shrink (the cell membrane capacitance Cm becomes smaller), the critical frequency f _C is increased. Here, the cell membrane capacity Cm decreases as the cell membrane increases (the number of fat cells increases) because the cell membranes enter the series, and the cell membrane resistance Rm increases as the cell membrane increases.

As described above, the critical frequency f _C changes according to the number of fat cells. When the number of fat cells increases (when the fat cells shrink), the capacity of fat sandwiched between the electrodes A and B decreases, and the critical frequency f _C increases. on the other hand,
If the number of fat cells decreases (the fat cells become enlarged)
The capacity of fat sandwiched between the electrodes A and B increases, and the critical frequency f _C decreases.

Therefore, the correspondence between the critical frequency f _C and the size of fat cells is stored in the RAM 5 or the like in advance, or an arithmetic algorithm or the like for directly calculating the size of fat cells from the critical frequency f _C is provided in advance. By doing so, the size of fat cells can be obtained.

Specifically, the CPU 3 calculates the bioelectric impedance calculated for each frequency by using the impedance locus D.
(See FIG. 8), the average value of the real parts of the two bioelectrical impedances where the imaginary part is zero is obtained,
A frequency in the average value as the critical frequency f _C, to calculate the size of the fat cells.

FIG. 8 is a diagram for explaining the impedance locus determined by the fat cell measuring device according to the present embodiment. The CPU 3 calculates the bioelectric impedance using the measured current and voltage values, and makes full use of the least squares calculation method for the bioelectric impedance Z (f) for each frequency as shown in FIG. A simple impedance locus D is obtained. From the obtained impedance locus D, the CPU 3 calculates the impedance R at the frequency 0 of the body of the subject.
_O and the impedance R∞ at infinite frequency are obtained,
From this result, intracellular fluid resistance Ri and the extracellular fluid resistance Re in the predetermined portion (abdomen) of the subject, further, calculates the size of fat cells on the basis of the critical frequency f _C.

As described above, it is possible to calculate the bioelectric impedance of fat having a predetermined shape substantially accommodated between the electrodes A and B and obtain the size of fat cells by focusing on the critical frequency f _C. Indicated. Next, FIG.
FIG. 7 shows that the critical frequency f _C does not depend on the thickness d of fat at the time of measurement.

FIGS. 5 to 7 are electrical equivalent circuit diagrams of fat cells. FIG. 6 is a further electrical equivalent circuit diagram of the circuit shown in FIG. 5, and FIG. 7 is a further electrical equivalent circuit diagram of the circuit shown in FIG. The electrical equivalent circuit shown in FIG.
The whole fat cell to be measured as exemplified in FIG. 2 is electrically shown. Specifically, one fat cell is composed of an intracellular fluid resistance ri, an extracellular fluid resistance re, a cell membrane capacity cm and a cell membrane resistance rm, like ordinary cells, and these fat cells are arranged in N rows and M columns. Are arranged. The electrodes A and B shown in FIGS. 2 and 3 are connected to the upper and lower ends of the equivalent circuit diagram shown in FIG.

The electrical equivalent circuit shown in FIG.
As shown in (1), the intracellular fluid resistance ri, extracellular fluid resistance re, cell membrane capacity cm, and cell membrane resistance rm constituting one fat cell can be expressed as a unit. Further, as shown in FIG. 7, the electrical equivalent circuit shown in FIG.
i, extracellular fluid resistance Re, cell membrane capacity Cm, and cell membrane resistance Rm. The circuit diagram shown in FIG. 7 is the same as that shown in FIG.

The intracellular fluid resistance Ri, extracellular fluid resistance Re, cell membrane capacity Cm and cell membrane resistance Rm shown in FIG. 7 are calculated by using the values of the circuit elements shown in FIGS. 5 and 6, Ri = (N / M)
ri, Re = (N / M) re, Rm = (N / M) rm, C
= (M / N) cm.

When calculating the critical frequency f _C , the following is assumed. (1) At the time of measurement (see FIG. 2), when the fat is pinched and sandwiched between the electrodes A and B, the pinch pressure does not substantially change the cell size, and the pinch is pinched depending on the fat cell size. The number of cells in the area changes. (2)
The surface area S and the electrode interval d of the electrodes A and B are known,
It is stored in the RAM 5 or the like in advance. The size of the electrodes A and B is sufficiently larger than the electrode interval (fat thickness) d.
(3) The cells are all the same size. In particular, the assumption (1) indicates that the number of fat cells having a predetermined shape sandwiched between the electrodes A and B to be measured differs for each subject, and the size of the fat cells is also the same.

[0047] In the electrical equivalent circuit shown in FIG. 7, the time constant tau _{is, τ = 1 / 2πf C =} Rm ((Re + Ri) / (Rm + Re + Ri)) Cm = ((N / M) 2 rm (re + ri)) / ((N / M) (rm + re + ri)) × (M / N) cm = rm (re + ri) / (rm + re + ri) (1) From the above, the time constant τ (critical frequency f _C ) is determined by the circuit constant (re, ri, rm, and cm) per fat cell.
And it does not depend on the number of adipocyte sequences (N rows and M columns). That is, the critical frequency f _C does not depend on the electrode interval d at the time of measurement.

Next, the operation of the fat cell measuring device according to the present embodiment will be described. Fat cell measuring device 1 having the above configuration
When 00 is used, first, prior to the measurement, fat in the abdomen of the subject is sandwiched between the electrodes A and B as shown in FIG. Next, the measurer (or the subject himself) uses the keyboard 1 of the fat cell measuring device 100 to input human body characteristic items such as the height, sex, and age of the subject, and performs all measurements from the start of measurement to the end of measurement. The time T and the measurement interval t are set. Data and setting values input from the keyboard 1 are stored in the RAM 5.

Next, when the measurer (or the subject himself) turns on the measurement start switch of the keyboard 1, the CPU 3
Sends a signal generation instruction signal to the measurement signal generator 72 of the measurement processing unit 2 after performing a predetermined initial setting. As a result, the measurement signal generator 72 repeatedly generates the M-sequence probe current Ia a predetermined number of times, and outputs LP as the measurement signal.
F73, the coupling capacitor 74, and the measurement signal Ia are transmitted to the electrode A contacting the upper surface of the abdomen of the subject via the measuring cable 7 which is a double shielded wire. Measurement is started.

When the measurement signal Ia is applied to the subject's body, the differential amplifier 81 of the measurement processing unit 2 outputs
The voltage Vp generated between c and Lc is detected and supplied to the A / D converter 83 via the LPF 82. On the other hand, in the I / V converter 91, the probe current Ia flowing between the electrodes A and B is
Is detected and converted to the voltage Vc, and then supplied to the A / D converter 93 via the LPF 92. At this time, CPU3
From the A / D converters 83 and 93 every sampling period.
Is supplied with a digital conversion signal Sd.

The A / D converter 83 converts the voltage Vp into a digital signal every time the digital conversion signal Sd is supplied, and supplies the digital signal to the sampling memory 84. The sampling memory 84 sequentially stores the digitized voltage Vp. On the other hand, the A / D converter 93 converts the voltage Vc into a digital signal each time the digital converted signal Sd is supplied, and supplies the digital signal to the sampling memory 94. The sampling memory 94 sequentially stores the digitized voltage Vc.

The CPU 3 calculates the probe current (measurement signal) I
When the number of repetitions of “a” reaches a preset number, after performing control to stop the measurement, first, the voltages Vp, which are stored in the sampling memories 84 and 94 and are a function of time, as a function of time.
The voltages Vp (f) and Vc (f), which are functions of frequency, are sequentially read out and subjected to Fourier transform processing.
(F is a frequency), and after averaging, bioelectric impedance Z (f) (= Vp (f) /
Vc (f)) is calculated.

Next, the CPU 3 performs curve fitting based on the obtained bioelectrical impedance Z (f) for each frequency by a calculation method of the least squares method, and generates an impedance locus D as shown in FIG. From the obtained and obtained impedance locus D, the average value of the real parts of the two bioelectric impedances whose imaginary parts are zero is obtained, and the size of the fat cell is calculated from the frequency (critical frequency f _C ) at the average value.

As described above, the CPU 3 stores the data in the RAM 5 or the like.
The previously stored critical frequency f _CAnd the size of fat cells
Calculate fat cell size based on correspondence
Or the critical frequency f_CThe size of fat cells directly from
Based on the calculation algorithm to calculate, the size of fat cells
Ask for it.

Next, the CPU 3 determines whether or not the total measurement time T has elapsed. If it is determined that the total measurement time T has elapsed, the CPU 3 terminates the subsequent measurement processing. After waiting for the corresponding time t to elapse, the same measurement processing is started again. Then, the above process is repeated until the entire measurement time T has elapsed.

As described above, according to the configuration of this example, the probe current Ia disperses in energy of about 1 msec despite including many frequency components.
Since the M-sequence signal whose amplitude of the frequency spectrum is substantially flat over the entire frequency range is used, the living body is not damaged when measuring the state of body fat or the distribution of water in the body. In addition, this makes it possible to remove the influence of respiration and pulse, and to achieve a good S / N ratio measurement over the entire frequency range. Further, the measurement signal can be generated only from the shift register and the plurality of logic circuits, so that the configuration becomes very simple.

Further, the bioelectrical impedance (or admittance) at an infinite frequency can be obtained by using a curve fitting method by the least square method, so that the influence of stray capacitance and external noise can be avoided, and the capacitance component of the cell membrane can be avoided. And the pure extracellular fluid resistance and the intracellular fluid resistance can be determined. The embodiments of the present invention have been described above in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and a design change or the like may be made without departing from the gist of the present invention. There may be.

First, in the above embodiment, in the impedance trajectory D (see FIG. 8), the critical frequency f _C is determined from the average value of the real parts of the two bioelectric impedances where the imaginary part is zero, and The size is calculated. As another form, the size of the fat cell may be calculated based on the frequency at which the absolute value of the imaginary part (capacity) of the impedance is maximized. In this case, for example, the CPU 3
Calculates the frequency of the impedance Z (f) having the largest imaginary part from the impedances in the impedance locus D as the critical frequency f _C , and calculates the size of the fat cell.

In this case, the size of the fat cell may be calculated by focusing on the change in the dielectric constant accompanying the change in the size of the fat cell. For example, the CPU 3 determines, from among the impedances in the impedance locus D, the imaginary part of the impedance Z (f) having the largest imaginary part and the electrodes A and B
Is calculated from the surface area S and the electrode interval d.
This dielectric constant is a parameter peculiar to the subject like the critical frequency f _C , and the correspondence between the dielectric constant and the fat cell is represented by R
The size of the fat cell can be calculated by storing it in the AM5 or the like in advance, or by previously providing an arithmetic algorithm for directly calculating the size of the fat cell from the dielectric constant.

In the above embodiment, the caliper 9 is used.
The fat cell size is calculated by sandwiching the fat in the abdomen (see FIG. 2). When the electrodes A and B are not fixed to the predetermined site to be measured as in this case, the size of the fat cells is corrected by taking the fat thickness (electrode interval) d at the time of measurement into consideration. Is also good. in this case,
A conversion process for bioelectric impedance is required.

Electrodes A, on the upper and lower surfaces of a fat having a thickness d and an area S,
When the bioelectrical impedance is measured by bringing B into contact (see FIG. 2), electricity flows into the fat through moisture slightly present in the fat. Although it is difficult for fat to pass an electric current, it can be slightly passed by changing the frequency.

Since the bioelectric impedance at this time changes depending on the surface area S of the electrodes A and B and the electrode interval (fat thickness) d, if the measured value is impedance, the bioelectric impedance is multiplied by S / d. (D / S times for admittance) and convert to bioelectrical impedance per predetermined shape. For example, if the area S and the thickness d are measured in units of “cm”, the cube “1 cm
^When calculating the size of fat cells specifically from the bioelectric impedance converted in this way, attention should be paid to the following points, and impedance measurement using a single frequency and fat Cell size measurements can be made.

When the fat cells are enlarged, the impedance Z (ω) also decreases on the low frequency side affected by the cell membrane resistance Rm. If the impedance is measured at a frequency that is not so large, it is observed that the impedance decreases due to the enlargement of fat cells. Therefore, CPU3
Calculates the size of fat cells based on the impedance value at a specific frequency. The CPU 3 converts the calculated bioelectric impedance Z (f) into a bioelectric impedance per predetermined shape in consideration of the surface area S of the electrodes A and B, the electrode interval d, and the like.

In this process, the size of the fat cell is calculated from the calculated bioelectrical impedance and the input electrode interval (fat thickness) d based on the measurement and the like. CPU3
Measures the bioelectric impedance of a predetermined shape and divides the bioelectric impedance Z (ω) by the thickness d of fat. Further, the size of the fat cell is calculated by calculating the dielectric constant from the imaginary part of the divided bioelectric impedance. As described above, since the size of fat cells can be calculated using a single or a small number of frequencies, simplification of the apparatus can be realized.

In the above embodiment, the size of the fat cell is calculated by sandwiching the fat with the caliper 9 (see FIG. 2). As another form, the size of fat cells may be calculated while retaining the shape of fat on the body of the subject. This will be described below with reference to FIG.

FIG. 9 is a diagram schematically illustrating another use state of the fat cell measuring device according to the embodiment of the present invention. FIG. 9A shows electrodes A,
FIG. 9B shows a case where B is fixed to a predetermined position of the subject and arranged on a flat plate, and FIG. 9B shows a state of electric lines of force during use based on FIG. 9A.

As shown in FIG. 9B, a plurality of lines of electric force converge from the electrode A to the electrode B, and it can be seen that the probe current Ia flows from the electrode A to the electrode B. According to this measurement, since the measurement can be performed only by bringing the electrode into contact with the fat tissue as it is, an easy-to-use device can be provided. In addition, since the electrodes A and B are fixed to a predetermined portion for measuring the size of the fat cell, the above-described conversion of the impedance is unnecessary.

In the above embodiment, the size of the fat cell is calculated by calculating the impedance. As another form, the size of fat cells may be calculated by calculating admittance and curve-fitting them to an admittance locus (not shown). In the above embodiment, the coupling capacitor 80
a, 80b are connected to the terminals Hc, Lc.
The measurement is performed by the two-terminal method. In another form,
The measurement may be performed based on a so-called four-terminal method. The shift register and the logic circuit constituting the M-sequence generator are not limited to a hardware configuration or a software configuration.

Further, in the above-described embodiment, a case has been described where the height, sex, and age of the subject are input as the human body characteristic items, but items such as race may be added as necessary. The calculated bioelectric parameters of the human body may be output to a printer. Further, a pulse wave sensor or a sensor capable of detecting a respiratory cycle may be attached to a human body, and the measurement timing may be set based on the output signal of each sensor.

[0070]

According to the fat cell measuring apparatus of the present invention, the size of fat cells can be calculated from the bioelectrical impedance, which is useful for the health management of the subject. In addition, measurement at a single frequency or multiple frequencies is possible, and the size of fat cells can be calculated from a critical frequency or the like using a simple algorithm or the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a fat cell measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a state of use of the fat cell measuring device according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between electrodes A and B and fat interposed between the electrodes in the measurement shown in FIG. 2;

4 is a diagram showing an electrical equivalent circuit of fat shown in FIG.

FIG. 5 is an electrical equivalent circuit diagram of a fat cell.

FIG. 6 is a further electrical equivalent circuit diagram of the circuit shown in FIG. 5;

FIG. 7 is a further electrical equivalent circuit diagram of the circuit shown in FIG. 6;

FIG. 8 is a diagram illustrating an impedance locus determined by the fat cell measuring device according to the embodiment of the present invention.

FIG. 9 is a diagram schematically illustrating another usage state of the fat cell measurement device according to the embodiment of the present invention.

FIG. 10 is an electrical equivalent circuit diagram of a human body (equivalent circuit model).
It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Keyboard 2 Measurement processing part 3 CPU (calculation means) 4 Display part 5 RAM 6 ROM 7, 8 Measurement cable 9 Vernier caliper 10 Main scale 11 Vernier 71 PIO 72 Measurement signal generator (part of signal generation means) 73 LPF (Part of signal generating means) 74, 80a, 80b Coupling capacitor 81 Differential amplifier (part of voltage measuring means) 82 LPF (part of voltage measuring means) 83, 93 A / D converter 84, 94 sampling Memory 91 I / V converter (part of current measuring means) 92 LPF (part of current measuring means) 100 Fat cell measuring device Hc, Lc terminal

Claims (6)

[Claims] 1. A signal generating means for generating a measurement signal, a current measuring means for measuring a current flowing when the generated measurement signal is applied between predetermined portions of a subject, and a potential difference generated between predetermined portions of the subject. A voltage measuring means for measuring the current value measured by the current measuring means and a voltage value measured by the voltage measuring means and a calculating means for calculating bioelectric impedance or admittance,
The fat cell measuring device, wherein the calculating means calculates a size of the fat cell based on the calculated bioelectric impedance or admittance. 2. The fat cell measuring device according to claim 1, wherein said calculating means calculates the size of the fat cell based on impedance or admittance at a specific frequency. 3. The fat cell measuring apparatus according to claim 1, wherein said calculating means calculates the size of the fat cell based on a frequency at which the absolute value of the imaginary part of impedance or admittance is maximum. . 4. The method according to claim 1, wherein the calculating means calculates the size of the fat cell based on the average frequency of two real parts of impedance or admittance in which the imaginary part of impedance or admittance is zero. The fat cell measurement device according to claim 1. 5. The fat cell measuring device according to claim 1, wherein the calculating means calculates the size of the fat cell based on impedance or admittance and fat thickness. 6. A signal generation step for generating a measurement signal, a current measurement step for measuring a current flowing when the generated measurement signal is applied between predetermined portions of the subject, and a potential difference generated between the predetermined portions of the subject. A voltage measurement step of measuring the current value measured by the current measurement step and a calculation step of calculating bioelectric impedance or admittance from the voltage value measured by the voltage measurement step, the calculation step, A fat cell measurement method, comprising calculating a size of a fat cell based on the calculated bioelectric impedance or admittance.