CN110448374B - Isolated human body impedance detection circuit and detection method - Google Patents
Isolated human body impedance detection circuit and detection method Download PDFInfo
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Abstract
The invention discloses an isolated human body impedance detection circuit and a detection method, wherein the circuit comprises a pulse generator, a data processing unit, a data display unit, one or more treatment electrodes and a channel or two impedance acquisition units, wherein the output end of the pulse generator is connected with the input end of the treatment electrode; and respectively preprocessing the voltage trigger signal and the current trigger signal, and then sending the preprocessed voltage trigger signal and the preprocessed current trigger signal into a data processing unit for calculation. The invention can detect the impedance of the human body, ensure the electroporation effect, play a role in monitoring the ablation effect in real time, and reduce the volume and the weight of a circuit of the detection equipment.
Description
Technical Field
The invention belongs to the technical field of human body impedance measurement, and particularly relates to an isolated human body impedance detection circuit and a detection method.
Background
The tumor ablation treatment technology is characterized in that under the guidance of images, energy such as radio frequency, microwaves, freezing, laser, an electric field and the like is extremely accurately punctured into a tumor target area, accurate minimally invasive ablation is implemented, and tumors are inactivated in situ, so that the method is a brand-new accurate minimally invasive operation. Thermal ablation destroys tumor cells by heating or freezing the tissue. The physical ablation technology widely applied in clinic at present comprises argon helium knife cryoablation, radio frequency, microwave, laser thermal ablation and the like. Although these ablative techniques have definite efficacy and outstanding advantages, they have the major disadvantage of indiscriminate tissue destruction, i.e., complete destruction of normal tissue organs such as blood vessels, nerves, bile ducts, pancreatic ducts, etc., except for tumor tissue, within the ablation zone. This disadvantage is the main cause of complications after ablation, such as massive hemorrhage after ablation, biliary tract system injury, intestinal perforation, and nerve dysfunction, which are common in clinic. This nonselective tissue destruction of thermal ablation greatly increases the risk of clinical application of this technique and severely limits its scope of clinical application. In addition, because the blood flow can take away heat, the thermal ablation effect is seriously affected by blood perfusion, and the thermal ablation is caused by tissue necrosis and is not easy to be discharged out of the body.
The nanometer knife ablation technology is to transmit a high-voltage electric field to tumor cells in the form of micropulses, change the transmembrane potential of the cells, cause nanoscale pores on lipid bilayer cell membranes, increase the permeability of the cell membranes, cause irreversible electroporation of tumor cells in a target area, and finally lead to death of the tumors. The nanometer knife ablates living cells, the cell matrix and the structure around the cells which are reserved in theory have little influence on the tissues such as blood vessels, bile ducts, nerves and the like in a treatment area, and are generally only restorable injuries, and the structures and functions of the nanometer knife are still kept intact. And because the nanometer knife is not thermally ablated, the nanometer knife is not influenced by blood flow, and complete cell death can be generated around blood vessels.
The nano-knife ablation process, if the applied electric field exceeds a certain threshold, will cause permanent disruption of cell membrane structure and cellular homeostasis, causing immune responses, leading to apoptosis. According to different tumors, the pulse electric field intensity is 1.5kV/cm, the pulse width is 20-1000 mu s, the pulse amplitude determines the volume of single ablation, the larger the volume of single ablation, the maximum output current can reach 50A, the pulse amplitude is 3kV, and the pulse power can reach 150kW; the pulse amplitude is 4.5kV, and the pulse power reaches 225kW. In the treatment process, when irreversible electroporation occurs to tissues, the impedance of biological tissues continuously changes along with the treatment process, the impedance of a human body needs to be calculated, the electroporation effect is ensured, and the ablation effect is monitored in real time. Currently, unipolar square wave pulses are mostly adopted clinically, the electric field intensity of the used pulses is 1.5kV/cm, the pulse width is 100 mu s, and the pulse amplitude is 3kV square waves. Since the impedance of biological tissue is continuously changed along with the treatment process, the impedance between the treatment electrodes can be reduced to 60 omega, and the direct measurement of the impedance of the human body has lower safety, that is, if a short circuit fault occurs, the energy is totally released to the patient, which has disastrous effects
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the isolated human body impedance detection circuit and the detection method, and the detection circuit can detect human body impedance, ensure electroporation effect, play a role in monitoring ablation in real time, improve electrical safety of an irreversible electroporation device circuit and reduce volume and weight of the electroporation device circuit by adopting an isolated AD conversion technology. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
According to an aspect of the present invention, there is provided an isolated human body impedance detection circuit, including a pulse generator, a data processing unit, a data display unit, one or more therapeutic electrodes, and one or more impedance acquisition units for acquiring human body impedance, wherein output ends of the pulse generator are respectively connected with input ends of the one or more therapeutic electrodes, acquisition input ends of the impedance acquisition units are respectively connected with output ends of the therapeutic electrodes, acquisition output ends of the impedance acquisition units are connected with input ends of the data processing unit, output ends of the data processing unit are connected with the data display unit, the therapeutic electrodes are used as detection points, and acquisition input ends of the impedance acquisition units acquire voltages and currents of therapeutic pulse signals of the detection points.
Preferably, each impedance acquisition unit comprises at least one voltage acquisition unit and one current acquisition unit, the treatment electrode comprises a voltage detection electrode and a current detection electrode, the output end of the pulse generator is respectively connected with the input end of the voltage detection electrode and the input end of the current detection electrode, the voltage acquisition unit comprises a voltage low-pass filter circuit, a voltage peak value holding circuit, a voltage signal attenuation circuit and a voltage isolation type A/D converter, the output end of the voltage detection electrode is connected with the input end of the voltage peak value holding circuit through the voltage low-pass filter circuit, and the output end of the voltage peak value holding circuit is connected with the first detection input end of the data processing unit through the voltage signal attenuation circuit and the voltage isolation type A/D converter; the current acquisition unit comprises a current low-pass filter circuit, a current peak value holding circuit, a current signal attenuation circuit and a current isolation type A/D converter, wherein the output end of the current detection electrode is connected with the input end of the current peak value holding circuit through the current low-pass filter circuit, and the output end of the current peak value holding circuit is connected with the second detection input end of the data processing unit through the current signal attenuation circuit and the current isolation type A/D converter.
Preferably, the voltage low-pass filter circuit includes a resistor R1 and a capacitor C1, the voltage peak hold circuit includes a first operational amplifier U1, a rectifying diode S1 and a capacitor C2, the voltage signal attenuation circuit includes a resistor R2, a resistor R3 and a second operational amplifier U2, one end of the resistor R1 is connected to the output end of the voltage detection electrode, the other end of the resistor R1 is connected to one end of the capacitor C1 and the positive input end of the first operational amplifier U1, the output end of the first operational amplifier U1 is connected to the anode of the rectifying diode S1, the negative electrode of the rectifying diode S1 is connected to one end of the capacitor C2, one end of the resistor R2 and the negative input end of the first operational amplifier U1, the other end of the resistor R2 is connected to one end of the resistor R3 and the positive input end of the second operational amplifier U2, the output end of the second operational amplifier U2 is connected to the negative input end of the second operational amplifier U2 and the negative input end of the voltage isolation type a/D converter, and the other end of the voltage isolation type a/D converter is connected to the other end of the capacitor C1, and the other end of the voltage acquisition unit is connected to the ground.
Preferably, the isolated a/D converter uses AMC1303MX converter chips.
Preferably, the voltage pulse amplitude output by the detection electrode is 5V-3000V.
Preferably, the plurality of detection electrodes are spirally or circularly arranged and fixed on a substrate, each detection electrode is 8mm-12mm, each electrode is spirally distributed on a human body or circularly surrounds the human body, when the impedance of deep tissues of the human body is detected, the detection electrodes are not used independently, the detection electrodes are used for detecting, secondary damage to the human body is avoided, the volume and the weight of a detection device circuit are reduced, each electrode is respectively contacted with the human body to form a detection point, and therefore the resolution precision of impedance detection is improved, and the sum of the impedance between detection points corresponding to the human body by each resistor is detected.
The invention also provides a detection method of the isolated human body impedance, which comprises the following steps:
Step S1, a treatment electrode is used as a detection point, at least one voltage acquisition unit and one current acquisition unit are used for acquiring a voltage trigger signal and a current trigger signal of the detection point, the treatment electrode comprises a voltage detection electrode and a current detection electrode, the voltage detection electrode and the current detection electrode are contacted with the detection point of a human body, then trigger signal sources are applied to the voltage detection electrode and the current detection electrode, and the voltage detection electrode and the current detection electrode respectively obtain the voltage trigger signal and the current trigger signal;
Step S2, the voltage trigger signal and the current trigger signal are respectively transmitted into an isolated A/D converter after signal attenuation, low-pass filtering, peak-voltage value maintaining and signal re-attenuation to obtain a voltage digital signal and a current digital signal;
And step S3, the voltage digital signal and the current digital signal are sent into a data processing unit, and are calculated through a preset resistance = voltage/current calculation model, so that the measured human body impedance value is calculated and displayed on a data display unit.
The above scheme is further preferable, the detection method further comprises the steps of applying a preset trigger signal source to one or more voltage detection electrodes and current detection electrodes through detection points of the one or more voltage detection electrodes and the current detection electrodes, continuously measuring in a preset time to obtain sampling point values of a plurality of voltage trigger signals and current trigger signals, calculating and averaging the sampling point values with a preset resistance=voltage/current calculation model, and calculating to obtain the measured impedance value of the human body.
In summary, the invention adopts the technical proposal and has the beneficial effects that:
(1) The detection circuit can detect the impedance of a human body, ensures the electroporation effect, can realize real-time monitoring and ablation effect, adopts an isolated AD conversion technology, improves the electrical safety of the irreversible electroporation equipment circuit, and reduces the volume and the weight of the electroporation equipment circuit.
(2) The peak value holding circuit can hold the pulse peak value of 100 mu s pulse width of each channel to 300 mu s pulse width, and the peak value after pulse shaping is held for a period of time by the peak value holding circuit as the input of the subsequent signal attenuation circuit. The invention adopts isolated human body impedance detection, not only observes electroporation effect, but also has isolation function.
Drawings
In order to more clearly illustrate the examples of the invention or the technical solutions in the prior art, the drawings required in the description of the embodiments or the prior art will be briefly described below, it being evident that the drawings in the description below are only some examples of the invention and that other drawings may be obtained from these drawings without any inventive effort for a person skilled in the art.
FIG. 1 is a schematic block diagram of an isolated body impedance detection circuit of the present invention;
FIG. 2 is a schematic circuit diagram of an isolated body impedance detection circuit of the present invention;
Fig. 3 is a detection flow chart of an isolated human body impedance detection method of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made more clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
According to one aspect of the present invention, in conjunction with fig. 1, the present invention provides an isolated human body impedance detection circuit, which includes a pulse generator, a data processing unit, a data display unit, one or more treatment electrodes, and one or more impedance acquisition units for acquiring human body impedance, wherein output ends of the pulse generator are respectively connected with input ends of one or more treatment electrodes, acquisition input ends of the impedance acquisition units are respectively connected with output ends of the treatment electrodes, acquisition output ends of the impedance acquisition units are connected with input ends of the data processing unit, output ends of the data processing unit are connected with the data display unit, the treatment electrodes are used as detection points, and acquisition input ends of the impedance acquisition units acquire voltages and currents of treatment pulse signals of the detection points. In the invention, each impedance acquisition unit at least comprises a voltage acquisition unit and a current acquisition unit, the treatment electrode comprises a voltage detection electrode and a current detection electrode, the output end of the pulse generator is respectively connected with the input end of the voltage detection electrode and the input end of the current detection electrode, the voltage acquisition unit comprises a voltage low-pass filter circuit, a voltage peak value holding circuit, a voltage signal attenuation circuit and a voltage isolation type A/D converter, the output end of the voltage detection electrode is connected with the input end of the voltage peak value holding circuit through the voltage low-pass filter circuit, and the output end of the voltage peak value holding circuit is connected with the first detection input end of the data processing unit through the voltage signal attenuation circuit and the voltage isolation type A/D converter; the current acquisition unit comprises a current low-pass filter circuit, a current peak value holding circuit, a current signal attenuation circuit and a current isolation type A/D converter, wherein the output end of the current detection electrode is connected with the input end of the current peak value holding circuit through the current low-pass filter circuit, and the output end of the current peak value holding circuit is connected with the second detection input end of the data processing unit through the current signal attenuation circuit and the current isolation type A/D converter.
In the present invention, as shown in fig. 1 and 2, the voltage low-pass filter circuit includes a resistor R1 and a capacitor C1, the voltage peak hold circuit includes a first operational amplifier U1, a rectifier diode S1 and a capacitor C2, the voltage signal attenuation circuit includes a resistor R2, a resistor R3 and a second operational amplifier U2, one end of the resistor R1 is connected to the output end of the voltage detection electrode, the other end of the resistor R1 is connected to one end of the capacitor C1 and the positive input end of the first operational amplifier U1, the output end of the first operational amplifier U1 is connected to the anode of the rectifier diode S1, the cathode of the rectifier diode S1 is connected to one end of the capacitor C2, one end of the resistor R2 and the negative input end of the first operational amplifier U1, the other end of the resistor R2 is connected to one end of the resistor R3 and the input end of the second operational amplifier U2, the positive output end of the second operational amplifier U2 is connected to the voltage-converting unit a/D of the second operational amplifier U2, and the other end of the voltage-converting unit is connected to the other end of the capacitor C4 and the other end of the capacitor C2 is connected to the input end of the data-collecting unit. In the invention, as shown in fig. 2, the circuit structure principle of a low-pass filter circuit, a peak current holding circuit, a current signal attenuation circuit and a current isolation type a/D converter in the current collecting unit is the same as the circuit principle of a low-pass filter circuit, a peak voltage holding circuit and a voltage signal attenuation circuit in the voltage collecting unit, the low-pass filter circuit comprises a resistor R11 and a capacitor C11, the peak current holding circuit comprises a second operational amplifier U11, a rectifier diode S11 and a capacitor C12, the current signal attenuation circuit comprises a resistor R12, a resistor R13 and a third operational amplifier U12, one end of the resistor R11 is connected with the output end of the current detection electrode, the other end of the resistor R11 is connected with one end of the capacitor C11 and the positive input end of the second operational amplifier U11 respectively, the negative electrode of the rectifier diode S11 is connected with one end of the capacitor C12 respectively, one end of the resistor R12 and one end of the second operational amplifier U12 are connected with the other end of the negative electrode of the second operational amplifier U12 respectively, the other end of the resistor U13 is connected with the other end of the third operational amplifier U13 and the other end of the capacitor U12 respectively, the other end of the third operational amplifier U is connected with the other end of the input end of the capacitor U13 and the output end of the third operational amplifier U13 respectively, the other end of the third operational amplifier is connected with the input end of the capacitor U13 and the other end of the output end of the third operational amplifier is connected with the output end of the capacitor is connected with the output end of the capacitor.
The working principle of the voltage acquisition unit is further described below, the voltage pulse amplitude output by the voltage detection electrode is 5V-3000V, the voltage peak value holding circuit is composed of a first operational amplifier U1, a rectifier diode S1 and a capacitor C2, and the pulse wave output by the detection electrode is filtered through a low-pass filter composed of a resistor R1 and the capacitor C1 to eliminate noise interference; the resistor R2 and the resistor R3 form a voltage attenuator, the input voltage is attenuated to be within the range of 250mv, so that the voltage isolation type A/D converter U3 is prevented from exceeding the range, the isolation type A/D converter U3 is borne by an AMC1303MX chip, the chip realizes two functions, namely, the isolation function for human impedance detection and the AD data conversion. The output of the voltage attenuator is sent to AINN ports of the voltage isolation type A/D converter U3 after passing through an operation follower formed by a second operational amplifier, and is connected in parallel by a capacitor C3 and a capacitor C4 to filter the nominal voltage provided by the 5V AVDD port of the analog power supply; the output end of the isolated A/D converter U3 is an isolated digital end, the modulated digital signal is output by a DOUT port and is connected in parallel by a capacitor C5 and a capacitor C6, the power supply provided by the digital power supply 5V DVDD digital port is filtered, in the invention, the digital signal output by the DOUT of the output end DOUT of AMC1303MX is used as a data input signal of a data processing unit, a 32-bit floating point type microprocessor U3 is used as a core processor for processing and analyzing the acquired signal, the processed result is displayed in a data display unit, the microprocessor U3 adopts a TMS320F2837X processor chip for calculation, an isolated human body impedance detection circuit adopts an AMC1303 chip, and the chip is an isolated input and output of a high-precision modulator. If the switch has a short circuit fault, the output end is isolated from the input end, and energy can be blocked from being released to a patient, so that the safety of the patient is protected, the AMC1303MX chip is applied to perform AD data conversion, and most importantly, the isolation function of human body impedance detection is performed, and the safety of a human body is ensured. AMC1303MX is a high-precision delta-sigma (ΔΣ) modulator, where the output and input circuits are isolated by a capacitive double isolation gate with high magnetic field immunity. The isolation gate was certified to provide enhanced isolation up to 7000V peak, according to DINV DE V0884-10 (semiconductor device-magnetic capacitive coupler standard for safety isolation), UL1577 (rating for device dielectric withstand voltage, voltage breakdown rating) and CSA standard (CANADIAN STANDARDS Association). When used in conjunction with an isolated power supply, the isolated modulator prevents noise current on the common mode high voltage line from entering the local system ground, thereby interfering with or damaging the low voltage circuitry and preventing damage to the lower voltage devices. Meanwhile, the isolation modulator AMC1303MX is optimized for direct connection to shunt resistors or other low voltage level signal sources, while having excellent dc and ac performance. By decimating the bit stream using an appropriate digital filter, a 16 bit resolution of 85dB (13.8 ENOB) dynamic range can be achieved at 78kSPS data rate. On the high side, the modulator is powered by a 5V (AVDD) nominal voltage, while the isolated digital interface is powered by a 3.3V or 5V power supply (DVDD) nominal voltage. When the impedance detection is started, the signal detected by the detection electrode is square wave pulse, and the pulse width determines the output pulse width on the electrode. The peak value holding circuit holds the pulse peak value of the pulse width of about 100 mu s of each channel to the pulse width of 300 mu s, and the peak value after pulse shaping is held for a period of time by the peak value holding circuit as the input of the subsequent signal attenuation circuit. After the high-frequency signal is subjected to signal attenuation through the signal attenuation module, the high-frequency signal is used as the input of the isolated A/D converter, the AMC1303MX chip can not only perform AD data conversion, but also perform isolation on human impedance detection, and the human impedance is calculated according to resistance=voltage/current. The invention adopts isolated human body impedance detection, not only can observe electroporation effect, but also has isolation effect.
In the present invention, in combination with fig. 1, 2 and 3, there is also provided a method for detecting isolated human body impedance, including the steps of:
Step S1, taking a treatment electrode as a detection point, collecting voltage trigger signals and current trigger signals (voltage and current of a treatment pulse signal) of the detection point at least through a voltage collecting unit and a current collecting unit, wherein the treatment electrode comprises a voltage detecting electrode and a current detecting electrode, the voltage detecting electrode and the current detecting electrode are contacted with the detection point of a human body, and then trigger signal sources are applied to the voltage detecting electrode and the current detecting electrode, so that the voltage detecting electrode and the current detecting electrode respectively obtain the voltage trigger signals and the current trigger signals; in the invention, trigger signal sources can be applied to the voltage detection electrodes and the current detection electrodes through one or more detection points where the voltage detection electrodes and the current detection electrodes contact a human body, so that the voltage detection electrodes and the current detection electrodes respectively obtain voltage trigger signals and current trigger signals; the voltage detection electrodes and the current detection electrodes are spirally or circularly arranged and fixed on a substrate, each detection electrode is 8-12 mm, each electrode is used as a detection point, repeated measurement is carried out through the detection points, and trigger signals of 128 or 256 sampling points are collected each time; continuously measuring the same detection point for 10s, so that the measured impedance value of the human body is more accurate;
step S2, the voltage trigger signal and the current trigger signal are respectively subjected to signal attenuation, low-pass filtering, peak value holding and signal re-attenuation and then are sent into an isolated A/D converter to obtain a voltage digital signal and a current digital signal, as shown in figure 3; the applied trigger signal source is a nanometer knife pulse generator, the nanometer knife pulse generator generates electric pulses, the pulse waveform, amplitude, repetition frequency, pulse width and pulse times directly influence the treatment effect, and therefore the voltage trigger signal and the current trigger signal can be fed into signal isolation and A/D conversion after being attenuated again so as to acquire voltage data output and current data output; since during the nano-knife ablation process, if the applied electric field exceeds a certain threshold, the cell membrane structure and intracellular homeostasis are permanently destroyed, and immune response is caused, thereby causing apoptosis. Therefore, irreversible electroporation (IRE) is generated on a phospholipid or a phospholipid protein membrane of a mammal by an electric pulse technology, the typical value of a mammal cell is up to 2.5kV/cm, the pulse electric field intensity output by a nanometer knife pulse generator is high enough to ensure the electroporation effect, when the mammal cell is subjected to irreversible electroporation, the nanometer knife pulse generator adopts square wave output waveforms, the constant voltage applied to a detection electrode (a treatment electrode 1 and a treatment electrode 2) is in a range of 500V-5000V, the repetition frequency is in a range of 1-2Hz, the pulse width is usually in a range of 1 mu s to hundreds mu s, and the pulse number is in a range of 1-199, so that when the nanometer knife ablation is carried out on a human body by a detection electrode, the impedance detection is carried out on the human body, the voltage data and the current data during the ablation are obtained, so that the electroporation effect is ensured, and the real-time monitoring of the ablation effect can be achieved;
And step S3, the voltage digital signal and the current digital signal are sent into a data processing unit, and are calculated through a preset resistance = voltage/current calculation model, so that the measured human body impedance value is calculated and displayed on a data display unit.
According to the invention, a preset trigger signal source is applied to one or more detection points of the voltage detection electrode and the current detection electrode, which are in contact with a human body, through the detection point of the human body, wherein the detection point of the voltage detection electrode and the current detection electrode is in contact with the human body, the preset trigger signal source is applied to the one or more detection points of the voltage detection electrode and the current detection electrode, continuous measurement is carried out within preset time, sampling point values of a plurality of voltage trigger signals and current trigger signals are obtained, the sampling point values are calculated and averaged with a preset resistance = voltage/current calculation model, the measured human body impedance value is calculated and obtained, the voltage detection electrode and the current detection electrode are spirally or circularly arranged and fixed on a substrate, each detection electrode is 8mm-12mm, the same detection point is continuously measured for 10s, multiple sampling is carried out within the measurement time, 128 or 256 sampling points are obtained, and the calculation and the average value is calculated and obtained through the resistance = voltage/current calculation model, so that the measured human body impedance value is more accurate.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (7)
1. A detection method of isolated human body impedance is characterized in that: the human body impedance detection is carried out by using an isolated human body impedance detection circuit, the human body impedance of the detection circuit comprises a pulse generator, a data processing unit, a data display unit, one or more treatment electrodes, and one or more than two channels and impedance acquisition units for acquiring human body impedance, the output end of the pulse generator is respectively connected with the input ends of one or more treatment electrodes, the acquisition input ends of the impedance acquisition units are respectively connected with the output ends of the treatment electrodes, the acquisition output ends of the impedance acquisition units are connected with the input ends of the data processing unit, and the output ends of the data processing unit are connected with the data display unit;
Each impedance acquisition unit at least comprises a voltage acquisition unit and a current acquisition unit, the treatment electrode comprises a voltage detection electrode and a current detection electrode, the output end of the pulse generator is respectively connected with the input end of the voltage detection electrode and the input end of the current detection electrode, the voltage acquisition unit comprises a voltage low-pass filter circuit, a voltage peak value holding circuit, a voltage signal attenuation circuit and a voltage isolation type A/D converter, the output end of the voltage detection electrode is connected with the input end of the voltage peak value holding circuit through the voltage low-pass filter circuit, and the output end of the voltage peak value holding circuit is connected with the first detection input end of the data processing unit through the voltage signal attenuation circuit and the voltage isolation type A/D converter; the current acquisition unit comprises a current low-pass filter circuit, a current peak value holding circuit, a current signal attenuation circuit and a current isolation type A/D converter, wherein the output end of the current detection electrode is connected with the input end of the current peak value holding circuit through the current low-pass filter circuit, and the output end of the current peak value holding circuit is connected with the second detection input end of the data processing unit through the current signal attenuation circuit and the current isolation type A/D converter;
the detection method comprises the following steps:
Step S1, a treatment electrode is used as a detection point, at least one voltage acquisition unit and one current acquisition unit are used for acquiring a voltage trigger signal and a current trigger signal of the detection point, the treatment electrode comprises a voltage detection electrode and a current detection electrode, the voltage detection electrode and the current detection electrode are contacted with the detection point of a human body, then trigger signal sources are applied to the voltage detection electrode and the current detection electrode, and the voltage detection electrode and the current detection electrode respectively obtain the voltage trigger signal and the current trigger signal;
Step S2, the voltage trigger signal and the current trigger signal are respectively transmitted into an isolated A/D converter after signal attenuation, low-pass filtering, peak-voltage value maintaining and signal re-attenuation to obtain a voltage digital signal and a current digital signal;
And step S3, the voltage digital signal and the current digital signal are sent into a data processing unit, and are calculated through a preset resistance = voltage/current calculation model, so that the measured human body impedance value is calculated and displayed on a data display unit.
2. The method for detecting isolated body impedance of claim 1, wherein: the voltage low-pass filter circuit comprises a resistor R1 and a capacitor C1, the voltage peak value holding circuit comprises a first operational amplifier U1, a rectifier diode S1 and a capacitor C2, the voltage signal attenuation circuit comprises a resistor R2, a resistor R3 and a second operational amplifier U2, one end of the resistor R1 is connected with the output end of the voltage detection electrode, the other end of the resistor R1 is respectively connected with one end of the capacitor C1 and the positive input end of the first operational amplifier U1, the output end of the first operational amplifier U1 is connected with the anode of the rectifier diode S1, the cathode of the rectifier diode S1 is respectively connected with one end of the capacitor C2, one end of the resistor R2 and the negative input end of the first operational amplifier U1, the other end of the resistor R2 is respectively connected with one end of the resistor R3 and the positive input end of the second operational amplifier U2, the output end of the second operational amplifier U2 is respectively connected with the negative input end of the second operational amplifier U2 and the positive input end of the voltage isolation type A/D converter, the output end of the voltage isolation type A/D converter is respectively connected with the other end of the capacitor C1 and the other end of the capacitor C2 is respectively connected with the other end of the capacitor C1.
3. The method for detecting isolated human body impedance according to claim 1 or 2, wherein: the isolated A/D converter adopts an AMC1303MX converter chip.
4. The method for detecting isolated human body impedance according to claim 1 or 2, wherein: the voltage pulse amplitude output by the voltage detection electrode is 5V-3000V.
5. The method for detecting isolated body impedance of claim 1, wherein: the voltage detection electrodes are spirally or circularly arranged and fixed on one substrate, each detection electrode is 8-12 mm, and the current detection electrodes are spirally or circularly arranged and fixed on one substrate.
6. The method according to claim 1 or 2, further comprising applying a predetermined trigger signal source to the one or more voltage detection electrodes and the current detection electrode through a detection point at which the one or more voltage detection electrodes and the current detection electrode contact the human body contacts the human body;
Continuously measuring in a preset time to obtain sampling point values of a plurality of voltage trigger signals and current trigger signals, calculating and averaging the sampling point values and a preset resistance = voltage/current calculation model, and calculating to obtain the measured human body impedance value .
7. The method according to claim 6, wherein a predetermined trigger signal source is applied to one or more voltage detection electrodes and current detection electrodes, and when continuous measurement is performed for a predetermined time, a trigger signal of 128 or 256 sampling points is collected each time, and continuous measurement is performed for 10s for the same detection point.
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| CN112039178B (en) * | 2020-08-31 | 2022-05-13 | 赛诺微医疗科技（浙江）有限公司 | Control method and device for irreversible electroporation ablation device |
| CN113143242A (en) * | 2021-04-12 | 2021-07-23 | 浙江大学 | Circuit system for measuring human body spinal bone reactance |
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