CN106419916B

CN106419916B - Human body electrophysiological parameter measuring device and method

Info

Publication number: CN106419916B
Application number: CN201611052232.7A
Authority: CN
Inventors: 贾林壮; 张捷; 赵振华; 孙培龙; 史熠
Original assignee: Shanghai Zhongjia Hengtai Medical Science & Technology Co ltd
Current assignee: Shanghai Zhongjia Hengtai Medical Science & Technology Co ltd
Priority date: 2016-11-25
Filing date: 2016-11-25
Publication date: 2023-08-01
Anticipated expiration: 2036-11-25
Also published as: CN106419916A

Abstract

The invention relates to a human electrophysiological parameter measuring device, which comprises four metal electrode plates and a main controller, wherein the main controller comprises an MCU control core (1), a USB interface (2), a power conversion circuit (3) and a four-way electrode measurement and control loop (4), the power conversion circuit (3) is respectively connected with the USB interface (2), the MCU control core (1) and the electrode measurement and control loop (4) and is used for converting a 5V power supply provided by the USB interface (2) into stable voltages with different magnitudes, the electrode measurement and control loop (4) is correspondingly connected with the metal electrode plates one by one and is respectively connected with the MCU control core (1) and is used for receiving the control of the MCU control core (1), connecting the metal electrode plates to set voltages or connecting resistances and then grounding, and sending voltage signals of the metal electrode plates to the MCU control core (1), and the MCU control core (1) is connected with the USB interface (2). Compared with the prior art, the invention has the advantages of comprehensiveness, accurate measurement result and the like.

Description

Human body electrophysiological parameter measuring device and method

Technical Field

The present invention relates to a device for measuring human body parameters, and more particularly, to a device and method for measuring human body electrophysiological parameters.

Background

Analysis and parameter determination of human electrophysiological models can provide important information for evaluation of health conditions and even disease diagnosis. The human body electrophysiological model is a non-uniform resistor and capacitor distributed parameter model, at present, human body electrophysiological parameters are almost all measured by externally adding different forms of electric signals to measure human body resistance or impedance, but the measurement method lacks research and analysis of the human body electrophysiological model, has great blindness, and the resistance or impedance measurement result is affected by human body capacitance and is not accurate enough. There are also extremely individual measurement of the capacitance of a human body, which is simply a measurement of the change in capacitance to ground caused by a human body touching a metal area on a circuit board, and is not a measurement of the actual capacitance of the human body. In a word, the measurement of the parameters of the electrophysiological model of the human body in the prior art is not comprehensive enough, so that the equivalent capacitance of the human body is ignored, and the measurement result is inaccurate due to the fact that the influence of the capacitance is ignored due to lack of knowledge of the electrophysiological model in the measurement of the resistance.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a high-accuracy human electrophysiological parameter measuring device and a high-accuracy human electrophysiological parameter measuring method.

The aim of the invention can be achieved by the following technical scheme:

the utility model provides a human electrophysiology parameter measuring device, includes four metal electrode boards and main control unit, main control unit include MCU control core, USB interface, power conversion circuit and four way electrode observe and control the return circuit, power conversion circuit respectively with USB interface, MCU control core and electrode observe and control the return circuit and be connected, electrode observe and control the return circuit and be connected with metal electrode board one-to-one to be connected with MCU control core respectively, MCU control core and USB interface connection, power conversion circuit convert the 5V power that the USB interface provided into the stable voltage of equidimension, electrode observe and control the return circuit and accept MCU control core control, make the metal electrode board connect the ground after settlement voltage or connecting resistance to with the voltage signal of metal electrode board and send MCU control core, MCU control core calculate human electrophysiology parameter and send to the USB interface. The set voltage is a safe direct-current voltage, and the value of the set voltage can be arbitrarily selected between 2 and 4V.

The electrode measurement and control loop comprises an ADC signal conditioning branch, a DAC driver branch, a digital potentiometer branch, a high-resistance branch and a grounding branch, wherein the ADC signal conditioning branch is used for connecting a metal electrode plate with an MCU control core, the DAC driver branch, the digital potentiometer branch, the high-resistance branch and the grounding branch are respectively connected to the metal electrode plate through a multi-way switch, and the metal electrode plate is respectively connected with a set voltage, the metal electrode plate is grounded in a variable resistance mode, the high-resistance mode and the direct ground mode.

The resistance value of the high-resistance branch is larger than 10MΩ.

The ADC signal conditioning branch circuit comprises a signal conditioning chip and an ADC chip, the signal conditioning chip is respectively connected with the metal electrode plate and the input end of the ADC chip, and the output end of the ADC chip is connected with the MCU control core.

The DAC driver branch circuit comprises a DAC chip and a driver, wherein the driver is respectively connected with the output end of the DAC chip and the multi-way switch, and the input end of the DAC chip is connected with the MCU control core.

A method for measuring human body electrophysiological parameters by using the device comprises the steps of equivalent human body electrophysiological model into five resistance-capacitance units, corresponding to limbs and trunk respectively, wherein each resistance-capacitance unit comprises a resistor R _s Resistance R _p And a capacitor C, wherein the resistor R _p In parallel with capacitor C and then with resistor R _s When in series connection and measurement, each metal electrode plate is in one-to-one contact with the left hand, the right hand, the left foot and the right foot, and parameter measurement is carried out on the four-limb resistance-capacitance units by adopting the same principle, wherein the measurement process of the left upper limb resistance-capacitance unit comprises the following steps: the MCU control core enables the left hand electrode to be connected with a set safe direct-current voltage through the electrode measurement and control loop, the counter electrode of the left hand electrode, namely the right hand electrode, is grounded in variable resistance, the near end passive electrode of the left hand electrode, namely the left foot electrode, is grounded in high resistance, the far end passive electrode of the left hand electrode, namely the right foot electrode, is grounded in high resistance, so that an electric network is formed between a human body and the measuring device, then the MCU control core continuously samples voltages on the four metal electrode plates simultaneously to obtain voltage signal waveforms, and parameters of the left upper limb resistance-capacitance unit are calculated according to the voltage signal waveform data and the grounding resistance value of each metal electrode plate.

Said resistor R _s The calculation formula is as follows:

wherein u is _A Is anode voltage waveform, namely the voltage waveform of the metal electrode plate connected with the resistance-capacitance unit to be tested, (0) represents the 1 st sampling point of the waveform, u _P1 Is the voltage waveform of the near-end passive electrode, u _C Is a cathode voltage waveform, namely a dual electrode voltage waveform, R _C Is the ground resistance of the cathode,

said resistor R _p The calculation formula is as follows:

where (N) represents the last sample point of the waveform,

the calculation formula of the capacitor C is as follows:

wherein i is _CX For the current waveform on the capacitor C, (n) represents the n+1th sampling point of the waveform, T _S For sampling interval, u _CX Is the voltage waveform across the capacitor C.

The voltage waveform u on the capacitor C _CX The calculation formula is as follows:

the current waveform i on the capacitor C _CX The calculation formula is as follows:

the waveform sampling time is 10 s-30 s.

Compared with the prior art, the invention has the following advantages:

(1) The device uses the USB interface to supply power and transmit data outwards, and a power supply conversion circuit is arranged in the device and is used for supplying power to the electrode measurement and control loop and the MCU control core, so that the device has a simple structure and does not need to use other power supplies; the voltage provided by the USB is safe and reliable.

(2) The MCU control core and the four electrode measurement and control loops are used for realizing independent control and measurement of the four metal electrode plates, so that the measurement of the electrophysiological parameters of the human body is more comprehensive.

(3) The electrode measurement and control loop comprises five branches, wherein four branches are connected with the MCU control core through a multi-path selection switch, so that the metal electrode plate has four different circuit connection states and is used for different functions in four times of resistance-capacitance unit parameter measurement; the other branch is kept on, so that the MCU control core continuously obtains the voltage of the electrode plate.

(4) The digital potentiometer branch circuit enables the metal electrode plate to be grounded in a variable resistance mode, and aims to adjust the voltage applied to a human body in each measurement process, so that the voltage is kept at a relatively fixed value, namely, the parameter measurement of each resistance-capacitance unit is kept under the same condition, and the reliability of the overall measurement result is improved.

(5) The method for measuring the human body electrophysiological parameters is based on researching and analyzing the human body electrophysiological model under the ultra-low direct current voltage, and not only measures the human body resistance, but also measures the equivalent capacitance in the model, so that the measurement of the human body electrophysiological parameters is more comprehensive; the model eliminates the influence of the equivalent capacitance of the human body on the measurement of the resistance of the human body, so that the measurement of the electrophysiological parameters of the human body is more accurate.

(6) In each measuring process, the sampling time of the voltage waveform lasts for 10 s-30 s, the duration of the capacitance effect is considered, and the time waste is reduced.

Drawings

FIG. 1 is a schematic diagram of a human body electrophysiological model and a connection relationship between the model and a metal electrode plate in the embodiment;

FIG. 2 is a schematic diagram showing the structure of the measuring apparatus according to the present embodiment;

FIG. 3 is a schematic diagram of a main controller according to the present embodiment;

reference numerals:

1 is an MCU control core; 2 is a USB interface; 3 is a power supply conversion circuit; 4 is an electrode measurement and control loop; 41 is an ADC signal conditioning branch; 42 is the DAC driver leg; 43 is a digital potentiometer arm; 44 is a high resistance branch; 45 is a ground branch; 46 is a multiple-way switch; 51. 52, 53, 54 are metal electrode plates, respectively.

Detailed Description

The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.

Example 1

In the embodiment, the equivalent resistance and the equivalent capacitance in the human body electrophysiological model under the ultra-low safe direct current voltage are measured through the limbs. When the four limbs are measured, the human body electrophysiological model is equivalent to five resistance-capacitance units shown in figure 1, wherein R _s1 And R is _s2 Is equivalent to series resistance R _p The equivalent parallel resistance is equal to the equivalent capacitance. Four resistance-capacitance units corresponding to four limbs are correspondingly connected with the metal electrode plates 51, 52, 53 and 54.

The human body electrophysiological parameter measurement device of the present embodiment is composed of four metal electrode plates 51, 52, 53, 54 and a main controller. As shown in fig. 3, the metal electrode plate is connected into an electrode measurement and control loop 4 in the main controller through a wire.

As shown in fig. 2, the main controller is composed of a USB interface 2, a power conversion circuit 3, four electrode measurement and control loops 4, and an MCU control core 1, as shown in fig. 2. The MCU control core 1 in the main controller is connected with the USB interface 2.

Four metal electrode plates 4, two of which are hand electrodes, wherein the hand centers of the two hands of the detected object face the electrode plates and are horizontally placed on the surfaces of the electrodes and are in close contact with each other during detection; the other two are foot electrode plates, and the tested object stands on the electrode plates with bare feet. To prevent corrosion by repeated exposure to perspiration during long-term testing, the electrode plates are typically made of stainless steel materials.

The power conversion circuit 3 converts the 5V power provided by the USB interface 2 into a stable voltage required by other parts of the main controller, such as 3.3V required by the MCU control core 1, 5V and ±9v required by the electrode measurement and control loop 4, and the like.

The four electrode measurement and control loops 4 have the same structure, and take one of them as an example, the internal composition and the connection relation with the MCU control core 1 are shown in fig. 3. The electrode measurement and control loop 4 mainly comprises an ADC signal conditioning branch 41, a DAC driver branch 42, a digital potentiometer branch 43, a high-resistance branch 44, a grounding branch 45 and a multi-way switch 46, and has the functions of realizing electrode state switching through a multi-way selector and measuring electrode voltage signals. The multiplexing switch causes the electrodes to have 4 selectable connections: DAC and driver, digital potentiometer, high resistance ground, direct ground, corresponding to four states of the electrodes: voltage output state, variable resistance grounding state, high resistance grounding state and direct grounding state. The voltage measuring function of the electrode measuring and controlling loop 4 is always in an active state no matter which state the electrode is in.

The MCU control core 1 is the control core of the main controller, and controls and realizes the whole measuring process. Taking the measurement process of the left hand electrode as an example, during measurement, the main controller controls the left hand electrode to be in a voltage output state through the electrode measurement and control loop 4, outputs a safe direct current voltage (for example, 3.0V) and adds the safe direct current voltage to the left hand of a human body through the left hand electrode, and the left hand electrode is called an anode at the moment. The right hand is used as a dual electrode called a cathode and is controlled to be in a variable resistance grounding state; the left foot electrode is called a proximal passive electrode, the right foot electrode is called a distal passive electrode, and the left foot electrode and the right foot electrode are controlled to be in a high-resistance grounding state (usually 10M omega-20M omega).

The purpose of placing the cathode in a varistor grounded state is to adjust the voltage applied to the human body during each measurement so that it maintains a relatively fixed value.

At this time, the human body and the external resistor form an electrical network, and the MCU control core 1 continuously collects voltage signal waveforms on the four electrodes at the same time. The current signal waveform of each electrode can be obtained from the voltage signal waveform data and the ground resistance value of the electrode.

Because of the capacitance effect, the current of each electrode gradually decreases and relatively stabilizes at a level, which lasts for about 10-30 seconds for most people, so that 30 seconds of data are continuously collected when any one electrode is electrified, and then the following three electrophysiological parameters are analyzed according to the circuit law: r is R _s 、R _p C, wherein R is _s ＝R _s1 +R _s2 。

The test process is specifically as follows:

1. cathode varistor adjustment:

after the anode output voltage was outputted for 30 seconds, the resistance value of the cathode digital potentiometer was adjusted so that the voltage applied between the left and right hands of the human body was about 2V, and then the resistance value was fixed. After the completion, the main controller sets all the 4 electrodes in a direct grounding state for more than 10 seconds, so that the human body equivalent capacitance is completely discharged.

2. Equivalent parameter determination

The dc voltage was again outputted at the anode for 30 seconds, and the voltage waveforms of the 4 electrodes were simultaneously collected. Then sequentially calculating parameters R of the anode corresponding limb (corresponding to the left hand in the step) equivalent resistance-capacitance unit according to the following steps (1) - (5) _s 、R _p C. The calculation formula of the electrophysiological parameters of the limbs corresponding to the cathodes can be deduced according to the derivation methods of formulas (1) to (5), and the electrophysiological parameters of the limbs corresponding to the passive electrodes cannot be calculated in this step.

After the measurement of the left hand is finished, the main controller places all the 4 electrodes in a direct grounding state for more than 10 seconds, so that the equivalent capacitance of the human body is completely discharged, then the measurement of the right hand, the left foot and the right foot is started according to the same method, and finally all equivalent parameter values in the model can be obtained through calculation respectively.

The four-limb measurement sequence has no influence on the result, the electrophysiological parameter corresponding to the anode in the left-hand measurement result is close to the electrophysiological parameter corresponding to the cathode in the right-hand measurement result, and the same situation can occur in the left-hand and right-hand measurement results.

Finally, the main controller calculates the R through the USB interface 2 _s 、R _p And C and other electrophysiological parameters are transmitted to the outside for processing, the whole measurement process needs to test the left hand, the right hand, the left foot and the right foot of the human body in sequence, and the electrophysiological parameters of different parts in the equivalent model are calculated by processing the data respectively.

The calculation method will be described by taking the anode as an example. At the moment of the initial voltage application, the capacitor is in an uncharged state, so there are:

wherein u is _A Is of anode voltage waveform, namely metal electricity connected with the resistance-capacitance unit to be testedPolar plate voltage waveform, (0) represents 1 st sampling point of waveform, u _P1 Is the voltage waveform of the near-end passive electrode, u _C Is a cathode voltage waveform, namely a dual electrode voltage waveform, R _C Is the ground resistance of the cathode,

at the end of the 30 second data, the capacitor is substantially full, when:

where (N) represents the last sample point of the waveform.

R is obtained by the formulas (1) and (2) _S 、R _P 。

Finally, to calculate the equivalent capacitance C, the voltage waveform u on the equivalent capacitance is calculated first _CX And current waveform i _CX ：

Where (n) represents the n+1th sampling point of the waveform. ,

from basic relations on equivalent capacitanceA calculation of the capacitance in the case of discrete sampling can be obtained:

wherein T is _S Is the sampling interval.

In practical application, the human body electrophysiological model can be simplified into a resistance-capacitance unit from five resistance-capacitance units, the measuring process is simplified into a step from four steps, and the calculation method of the three parameters is identical to the formulas (1) - (5).

Example 2

The utility model provides a human electrophysiology parameter survey device, still includes the host computer, USB interface 2 is connected with the host computer, therefore USB interface 2 both is the interface that the host computer provided the power for the main control unit, also is the data communication channel of main control unit and host computer, consequently whole device need not to dispose other external power source again, convenient to use.

The remainder was the same as in example 1.

Claims

1. The utility model provides a human electrophysiology parameter measurement device, its characterized in that includes four metal electrode plates and main control unit, main control unit include MCU control core (1), USB interface (2), power conversion circuit (3) and four way electrode observe and control return circuit (4), power conversion circuit (3) be connected with USB interface (2), MCU control core (1) and electrode observe and control return circuit (4) respectively, electrode observe and control return circuit (4) and metal electrode plates one-to-one to be connected with MCU control core (1) respectively, MCU control core (1) be connected with USB interface (2), power conversion circuit (3) convert the 5V power that USB interface (2) provided into the stable voltage of equidimension, electrode observe and control return circuit (4) accept MCU control core (1) control, make metal electrode plates connect the voltage of settlement or connect the voltage signal ground after the resistance to send MCU control core (1), MCU control core (1) calculate human physiology parameter and send to USB interface (2);

the electrode measurement and control loop (4) comprises an ADC signal conditioning branch circuit (41), a DAC driver branch circuit (42), a digital potentiometer branch circuit (43), a high-resistance branch circuit (44) and a grounding branch circuit (45), wherein the ADC signal conditioning branch circuit (41) is used for connecting a metal electrode plate with the MCU control core (1), and the DAC driver branch circuit (42), the digital potentiometer branch circuit (43), the high-resistance branch circuit (44) and the grounding branch circuit (45) are respectively connected to the metal electrode plate through a multi-way switch (46) so as to respectively enable the metal electrode plate to be connected with a set voltage, be grounded in a variable resistance mode, be grounded in a high resistance mode and be directly grounded.

2. The device according to claim 1, wherein the high-resistance branch (44) has a resistance greater than 10mΩ.

3. The human electrophysiological parameter measurement device according to claim 1, wherein the ADC signal conditioning branch (41) comprises a signal conditioning chip (411) and an ADC chip (412), the signal conditioning chip (411) is connected to the metal electrode plate and the input end of the ADC chip (412), and the output end of the ADC chip (412) is connected to the MCU control core (1).

4. The device for measuring the electrophysiological parameters of the human body according to claim 1, wherein the DAC driver branch (42) comprises a DAC chip (421) and a driver (422), the driver (422) is respectively connected with the output end of the DAC chip (421) and the multi-way switch (46), and the input end of the DAC chip (421) is connected with the MCU control core (1).

5. A method for measuring human body electrophysiological parameters by using the device as claimed in any one of claims 1-4, wherein the method is characterized in that the human body electrophysiological model is equivalent to five resistance-capacitance units, corresponding to limbs and trunk respectively, each resistance-capacitance unit comprises a resistor R _s Resistance R _p And a capacitor C, wherein the resistor R _p In parallel with capacitor C and then with resistor R _s When in series connection and measurement, each metal electrode plate is in one-to-one contact with the left hand, the right hand, the left foot and the right foot, and parameter measurement is carried out on the four-limb resistance-capacitance units by adopting the same principle, wherein the measurement process of the left upper limb resistance-capacitance unit comprises the following steps: the MCU control core (1) connects the left hand electrode with the set safe direct current voltage through the electrode measurement and control loop (4), the counter electrode of the left hand electrode, namely the right hand electrode varistor is grounded, the near end passive electrode of the left hand electrode, namely the left foot electrode, is grounded, the far end passive electrode of the left hand electrode, namely the right foot electrode, is grounded, so that the human body and the measuring device form an electrical network, then the MCU control core (1) continuously samples the voltages on the four metal electrode plates at the same time to obtain voltage signal waveforms,and calculating the parameters of the left upper limb resistance-capacitance unit according to the voltage signal waveform data and the grounding resistance value of each metal electrode plate.

6. The method of claim 5, wherein the resistor R _s The calculation formula is as follows:

said resistor R _p The calculation formula is as follows:

where (N) represents the last sample point of the waveform,

the calculation formula of the capacitor C is as follows:

7. The method of claim 6, wherein the voltage waveform u across the capacitor C _CX The calculation formula is as follows:

8. the method of claim 5, wherein the waveform sampling time is between 10s and 30s.