Subcutaneous fluid change monitoring device and impedance value measurement method

Abstract

The application belongs to the field of medical equipment, and particularly relates to a subcutaneous effusion change monitoring device and an impedance value measurement method. The device comprises a control unit, an electrode patch detachably connected with the control unit, a sheet-shaped carrier and an electrode sheet. An electrode point for mounting the electrode sheet is arranged on the upper surface of the sheet-shaped carrier, and a sticking layer is arranged on the lower surface of the sheet-shaped carrier. The electrode sheet comprises a measurement electrode pair and at least two pairs of parallel arranged excitation electrode pairs. All the excitation electrode pairs are used for applying excitation signals to form a cage-shaped field region containing a bundle of equipotential lines. The connecting line of the measurement electrode pair is perpendicular to the bundle of equipotential lines and is located at the central position of the cage-shaped field region, and is used for measuring a first voltage difference of the cage-shaped field region. The control unit is configured to provide power to the excitation electrode pairs, control the measurement electrode pair to measure the first voltage difference to obtain the impedance value of the cage-shaped field region, and determine the subcutaneous effusion change monitoring result according to the change of the impedance value. The application realizes the effect of non-invasive and accurate monitoring of the subcutaneous effusion change.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical devices, and particularly relates to a subcutaneous effusion change monitoring device and an impedance value measurement method. BACKGROUND

[0002] Subcutaneous effusion is easy to cause subcutaneous tumors, local swelling, and higher than normal tissue, which can harm the health of the body. The common causes of subcutaneous effusion are: first, subcutaneous hematoma after contusion, including chronic effusion formed by liquefaction of post-traumatic hematoma, and second, postoperative wound. Effusion can be blood, pus, or relatively clear tissue exudate.

[0003] Traditional subcutaneous effusion change monitoring relies on clinical observation by doctors, imaging examination, and laboratory detection. However, these methods usually require professional equipment and manual analysis, making it difficult to conduct real-time, portable, and continuous monitoring. With the continuous development of technologies such as the Internet of Things, sensor technology, big data, and artificial intelligence, subcutaneous effusion change monitoring technology is also constantly improving. In recent years, many subcutaneous effusion change monitoring devices have been developed.

[0004] Among them, the subcutaneous effusion change monitoring device is mainly a subcutaneous bleeding monitoring device. Subcutaneous bleeding refers to the phenomenon of blood seeping into the surrounding tissue due to the rupture of small blood vessels under the skin. This condition can be caused by trauma, surgery, anticoagulant therapy, blood clotting dysfunction, etc.

[0005] Patent document CN 112437631 A discloses a directional and regional bioimpedance bleeding detection technology. The system of the technology includes: a guide, which can be used to insert a catheter into a blood vessel of a patient, the guide including a hollow sheath to receive the catheter when the catheter is inserted into the blood vessel; a first plurality of electrodes disposed on the sheath; and a measurement device coupled to the electrodes, the measurement device configured to: detect bleeding in the patient at a first region along the sheath by determining an impedance between a first pair of electrodes of the first plurality of electrodes; and detect bleeding in the patient at a second region along the sheath by determining an impedance between a second pair of electrodes of the first plurality of electrodes. However, this application requires inserting a catheter with electrodes into human tissue, which is an invasive solution. The mechanical sensor can only be inserted into the body through surgical cooperation with magnetic resonance imaging, which poses a risk of damage to the human body and is likely to cause psychological burden to the patient. At the same time, this invasive solution can only be used for patients lying in bed, affecting the normal life of the patient and cannot be worn for daily monitoring. Moreover, the host device and the electrode sensor need to be connected through wires, which may introduce the conduction impedance of the wires themselves and external interference (such as power frequency), and the host device needs to be suspended on the patient's body during use, which is an unreasonable product design.

[0006] In view of this, it is necessary to develop a subcutaneous fluid change monitoring device capable of non-invasive measurement, having an integrated design, small device size, and good monitoring accuracy. SUMMARY

[0007] The purpose of the present application is to provide a subcutaneous fluid change monitoring device and an impedance value measurement method to solve the problems of monitoring risk, data interference, unreasonable monitoring device structure, and inability to wear for daily monitoring in the prior art.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] According to a first aspect of the present application, a subcutaneous fluid change monitoring device is provided, comprising:

[0010] a control unit;

[0011] an electrode patch, detachably connected with the control unit, the electrode patch comprising a sheet-shaped carrier and an electrode sheet, the upper surface of the sheet-shaped carrier being provided with electrode points for mounting the electrode sheet, and the lower surface of the sheet-shaped carrier being provided with a fitting layer for fitting a target object;

[0012] wherein the electrode sheet comprises a measurement electrode pair (22) and at least two pairs of excitation electrode pairs (23) arranged in parallel, the at least two pairs of excitation electrode pairs (23) being used to apply an excitation signal of a predetermined frequency to form a cage-shaped field region containing a bundle of equipotential lines, the center line of the measurement electrode pair (22) being perpendicular to the bundle of equipotential lines and located at the central position of the cage-shaped field region, for measuring a first voltage difference of the cage-shaped field region;

[0013] the control unit is configured to: provide power to the excitation electrode pairs (23) to form the cage-shaped field region in the monitoring area of the target object; control the measurement electrode pair (22) to measure the first voltage difference to obtain the impedance value of the monitoring area, and determine the subcutaneous fluid change monitoring result according to the change of the impedance value.

[0014] In some embodiments, the ratio of the first spacing of each excitation electrode pair to the second spacing of the measurement electrode pair satisfies a predetermined multiple range,

[0015] the cage-shaped field region is divided into a first half and a second half by the perpendicular bisector of the straight line corresponding to the first spacing, the positive terminal of the measurement electrode pair and the positive terminals of all the excitation electrode pairs are distributed in the first half, and the negative terminal of the measurement electrode pair and the negative terminals of all the excitation electrode pairs are distributed in the second half.

[0016] In some embodiments, the control unit further comprises a calibration unit, which is configured to:

[0017] Collect the impedance value and standardize it, perform data filtering on the standardized impedance value based on a preset filtering function, and take the processing result as the calibrated impedance value;

[0018] Extract target condition features based on the calibrated impedance value, and input the target condition features into a pre-trained model to obtain a subcutaneous fluid change probability, and determine whether the subcutaneous fluid change probability reaches a preset probability;

[0019] In response to the subcutaneous fluid change probability reaching the preset probability, monitor the decline rate of the calibrated impedance value, and determine the subcutaneous fluid change monitoring result of the to-be-monitored area according to the decline rate;

[0020] The target condition features include width features, area features, depth features, kurtosis features, distribution map features, and complexity features.

[0021] In some embodiments, a second electrode patch identical in structure to the electrode patch and having a cage-shaped field range identical to or different from that of the electrode patch is further included, and the second electrode patch can replace the electrode patch and be detachably connected to the control unit.

[0022] In some embodiments, the control unit further includes a microprocessor configured to:

[0023] convert the current flowing through the measurement electrode pair into a second voltage difference,

[0024] Collect the first voltage difference and the second voltage difference, and perform discrete Fourier transform processing on the collected data to obtain target voltage values and target current values;

[0025] Determine voltage amplitude and current amplitude based on the target voltage values and the target current values;

[0026] Obtain the impedance value based on the voltage amplitude and the current amplitude.

[0027] In some embodiments,

[0028] The control unit (1) further includes an alarm state indicator light (3) and a buzzer (4) communicatively connected to the calibration unit, respectively, the alarm state indicator light (3) is used to trigger light consistent with the alarm indication level according to the alarm indication of the calibration unit, and the buzzer (4) is used to trigger sound effects consistent with the alarm indication level according to the alarm indication of the calibration unit;

[0029] The calibration unit is further configured to:

[0030] Determine whether the decline rate reaches a first threshold value;

[0031] If the falling rate reaches a first threshold value, a first-level alarm indication is triggered, and a current calibrated impedance value is taken as a reference impedance value, and the percentage change of the calibrated impedance value compared with the reference impedance value is continuously monitored;

[0032] If the percentage change reaches a first preset percentage, a second-level alarm indication is triggered, and if the percentage change reaches a second preset percentage lower than the first preset percentage, a third-level alarm indication is triggered.

[0033] In some embodiments, the control unit further comprises a three-axis acceleration sensor, which is in communication connection with the calibration unit, for measuring the pitch angle information of the target object and sending it to the calibration unit, so that the calibration unit calibrates the impedance value according to the pitch angle.

[0034] In some embodiments, the sheet-shaped carrier comprises a flexible and breathable material with a thickness ranging from 1 to 5 mm.

[0035] In some embodiments, the at least two pairs of excitation electrode pairs (23) comprise a first excitation electrode pair and a second excitation electrode pair, which are installed in parallel on the upper surface of the sheet-shaped carrier (2), the measurement electrode pair (22) is installed at a position equally spaced from the first excitation electrode pair and the second excitation electrode pair on the upper surface of the sheet-shaped carrier (2), and the midpoint of the connection line of the measurement electrode pair (22), the midpoint of the connection line of the first excitation electrode pair, and the midpoint of the connection line of the second excitation electrode pair are located on the same straight line.

[0036] Another aspect of the embodiments of the present application also provides an impedance value measurement method, comprising:

[0037] Applying an excitation signal of a preset frequency to the target object through at least two pairs of excitation electrode pairs to form a cage-shaped field domain containing a bundle of equipotential lines in the region to be monitored of the target object;

[0038] Measuring a first voltage difference through a measurement electrode pair located at the central position of the cage-shaped field domain and having a center connection line perpendicular to the bundle of equipotential lines;

[0039] Determining the impedance value of the region to be monitored according to the first voltage difference.

[0040] By using the above technical solutions, the present application has at least the following beneficial effects:

[0041] The subcutaneous fluid change monitoring device provided by the application is optimized for medical instrument products using impedance measurement. The excitation electrode pairs and the measurement electrode pairs are arranged in a specific manner on the electrode patch, so that after the device is started, the excitation signal applied by the device forms a cage-shaped field and forces the current to flow through the target object to be detected. The problem of excessive measurement range, low sensitivity and inaccurate measurement caused by the diffusion of the current to the surrounding tissue is avoided. The measurement electrode pairs are arranged according to the position of the cage-shaped field to ensure that the measurement range is accurate and the signal sensitivity is optimal. The device can only respond to the impedance change caused by the subcutaneous fluid change of the detection area, avoid the interference of the surrounding tissue, and obtain accurate subcutaneous fluid change monitoring results, thereby ensuring the accuracy and reliability of the detection of the subcutaneous fluid change on the skin surface. The device provides a high-reliability hardware foundation for non-invasive subcutaneous fluid change monitoring. The device can be attached to the skin to realize all-weather real-time monitoring of the subcutaneous fluid change, and timely provide a reference for doctors and patients. The device is especially suitable for postoperative monitoring or early subcutaneous fluid change warning in emergency scenes. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed by the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 The structural layout of the subcutaneous fluid change monitoring device provided by an embodiment of the application is shown in the figure.

[0044] Figure 2 The schematic diagram of the two pairs of excitation electrode pairs forming a cage-shaped field provided by an embodiment of the application is shown in the figure.

[0045] Figure 3 The schematic diagram of the arc-shaped excitation electrode pairs forming a cage-shaped field provided by an embodiment of the application is shown in the figure.

[0046] Figure 4 The schematic diagram of the control unit circuit design provided by an embodiment of the application is shown in the figure.

[0047] Figure 5 The schematic diagram of the impedance value-time change for subcutaneous fluid change determination under different conditions provided by an embodiment of the application is shown in the figure.

[0048] Figure 6 The schematic diagram of the distribution design of the excitation electrode pairs and the measurement electrode pairs in the sheet-shaped carrier provided by an embodiment of the application is shown in the figure.

[0049] Figure 7 The schematic diagram of the impedance value measurement method provided by an embodiment of the application is shown in the figure.

[0050] List of reference signs

[0051] 1 control unit; 2 electrode patch; 21 sheet carrier; 22 measuring electrode pair; 23 excitation electrode pair; 221 positive terminal of measuring electrode pair; 222 negative terminal of measuring electrode pair; 231 positive terminal of excitation electrode pair; 232 negative terminal of excitation electrode pair; 24 electrode patch electric connection line; 3 alarm state indicator light; 4 buzzer; 5 three-axis acceleration sensor; 6 lithium battery; 7 battery pull-out sheet; 8 state indicator light; 9 reset button, 10 pot sheet calibration key; 11 PCBA circuit board; 12 control unit and sheet carrier connection line; 13 lithium battery positive electrode; 14 lithium battery negative electrode. DETAILED DESCRIPTION

[0052] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application are further described in detail below with reference to the drawings. In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0053] It should be noted that the structures, proportions, sizes and the like shown in the drawings of the specification are only used to cooperate with the content described in the specification, so as to be understood and read by those skilled in the art, and do not have technical substantive significance, and any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the present application, should fall within the scope of the technical content disclosed by the present application.

[0054] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. The terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. The term "or" is generally used in the sense of including "and / or", unless the context clearly indicates otherwise.

[0055] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. The terms "bottom," "top," "lower part," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0056] The present invention will be further described in detail below with reference to the accompanying drawings.

[0057] The subcutaneous fluid accumulation described in this application refers to the presence of bloody, purulent, or relatively clear tissue exudate in the subcutaneous tissue. The main characteristic of subcutaneous fluid accumulation is a corresponding change in the impedance value of the subcutaneous tissue.

[0058] This invention provides a device for monitoring changes in subcutaneous fluid accumulation. For example... Figure 1 As shown, the subcutaneous fluid change monitoring device includes a control unit 1 and electrode patches 2.

[0059] Electrode patch 2 is detachably connected to control unit 1. Electrode patch 2 includes a sheet-like carrier 21 and electrode sheets. The upper surface of the sheet-like carrier 21 is provided with electrode points for mounting the electrode sheets, and the lower surface of the sheet-like carrier 21 is provided with an adhesion layer for adhering to a target object. The electrode sheets include measuring electrode pairs 22 and at least two pairs of excitation electrode pairs 23.

[0060] In one embodiment, the electrode patch 2 is a disposable electrode patch that is detachably connected to the control unit 1. Using disposable electrode patches 2 eliminates the need for reuse between different patients, ensuring hygiene, safety, convenience, efficiency, and improved patient comfort. The electrode patch 2 and control unit 1 are integrated into a single unit connected by a flexible flat cable. The overall thickness and size of the device are small. Compared to the separate design of the main unit and electrode sensors in existing technologies, this design offers advantages in terms of lightness and thinness, improving user comfort, avoiding monitoring errors caused by introduced wires, and enhancing the overall device's anti-interference capability.

[0061] In the illustrated embodiment, as Figure 1As shown, the structural layout of the subcutaneous fluid change monitoring device is illustrated. The control unit 1 internally uses a printed circuit board assembly hard board or FPC (Flexible Printed Circuit) as a carrier, and installs the microcontroller circuit, lithium battery power supply circuit, buzzer circuit and other hardware circuits on the circuit board as the control board of the control unit 1. The electrode patch 2 can use a sheet carrier 21 to realize the portable monitoring effect of being pasted to the human skin by cooperating with the metal conductive rivet, solid gel and electrode sheet. The sheet carrier 21 can be a flexible and breathable material such as non-woven fabric or textile fabric with double-sided adhesive tape with a thickness range of 1-5mm, which has the advantages of breathable, lightweight and non-irritating, and can reduce the foreign body sensation caused by long-term pasting on the skin. The solid gel is not easy to deform, hard and has good moisture-proof and stain-proof performance, which is arranged on the lower surface of the sheet carrier 21 for pasting the skin of the target object, can maintain stable contact between the skin and the electrode, and reduce signal interference caused by body movement. The metal conductive rivet is arranged on the lower surface of the sheet carrier 21, used for connecting the electrode sheet and the conductive adhesive layer, realizing the transmission of electrical signals between the biological tissue in the detection area and the electrode sheet. Through the close combination of the metal conductive rivet and the sheet carrier 21, the stable conductivity is ensured, and it has good corrosion resistance and is suitable for long-term signal acquisition.

[0062] At least two pairs of excitation electrode pairs 23 in the electrode sheet are arranged in parallel. Among them, parallel arrangement refers to that the connecting line L1 of the positive electrode in each excitation electrode pair is arranged in parallel with the connecting line L2 of the negative electrode in each excitation electrode pair. The at least two pairs of excitation electrode pairs 23 arranged in parallel form a cage-shaped field domain containing a bundle of equipotential lines after applying an excitation signal of a predetermined frequency.

[0063] In the detection of the position of the subcutaneous fluid change, one implementation based on is to arrange the electrode patch in the monitoring area, and the monitoring area is an area containing a potential change amount of subcutaneous fluid. In the related art, only a single excitation electrode pair is used to inject an excitation signal, and when the current flows from F+ to F-, the path naturally spreads to form a wider electric field distribution. The impedance value reflected by the voltage difference measured by the measurement electrode pair located in the spread electric field will contain all the biological tissues through which the current flows, that is, the biological tissues in the detection area and the surrounding biological tissues. The dispersion of the current path leads to an excessively large measurement area, and the signal of the detection area is "diluted" by the impedance of the surrounding biological tissues, resulting in that the calculated impedance value is the parallel result of the biological tissues in the detection area and the surrounding biological tissues, so it is difficult to focus on the impedance change of the subcutaneous fluid change point.

[0064] In this invention, the electrode pads employ at least two pairs of excitation electrodes and one pair of measurement electrodes. All electrode pads need to be arranged in a specific array pattern. The ultimate goal is to enable at least two pairs of excitation electrodes 23 to form a cage-like field containing equipotential wire bundles, thereby enabling the device to accurately monitor changes in subcutaneous fluid accumulation in the area to be detected on the skin surface and trigger an alarm.

[0065] Specifically, with Figure 2 For example, when the electrode sheet contains two symmetrically arranged pairs of excitation electrodes, the two pairs of excitation electrodes simultaneously apply excitation signals of a preset frequency, forming a cage-like field in the detection area through superimposed electric fields. The range of this cage-like field is determined by the distance between the positive and negative ends of the excitation electrode pairs and the relative positions of the two pairs of excitation electrodes. Within the cage-like field, the transverse (referring to the direction perpendicular to the excitation electrode pairs) current components cancel each other out, while the longitudinal current components are superimposed and enhanced. The electric field distribution is uniform, and the potential lines are dense and parallel, forming an equipotential line bundle perpendicular to the excitation electrode pairs. The formation of the cage-like field forces the current to be confined within the detection area and forms a closed loop flowing longitudinally, avoiding current diffusion and excessive attenuation of deep electrical signals. Figure 2 The dashed lines shown represent equipotential lines, the black arrows represent electric field lines, and the black dots represent the virtual centers of the cage-like field. Based on the above principles, using... Figure 3 The arc-shaped excitation electrode pairs or two or more excitation electrode pairs shown can also form a similar cage-shaped field.

[0066] The line connecting the measuring electrode pair 22 is perpendicular to the equipotential line bundle and located at the center of the cage-like field, used to measure the first voltage difference in the cage-like field. The control unit is configured to: supply power to the excitation electrode pair 23 to form a cage-like field in the area to be monitored of the target object, control the measuring electrode pair 22 to measure the first voltage difference to obtain the impedance value of the area to be monitored, and determine the monitoring result of subcutaneous effusion change based on the change in impedance value.

[0067] The measurement electrode pair 22 is arranged at the central position of the cage-shaped field, and the line connecting the measurement electrode pair is perpendicular to the equipotential line bundle, which can maximize the capture of the electrical signal, has high measurement sensitivity and signal resolution. Because the subcutaneous fluid change tissue is rich in electrolytes (such as blood), the resistivity is significantly lower than that of the surrounding biological tissue, which is equivalent to a minimum equivalent resistance. When the amount of subcutaneous fluid change in the region to be detected changes, the cage-shaped field is constrained by the electric field, so that the current preferentially flows through the minimum resistance path (i.e. the subcutaneous fluid change tissue). In the equivalent circuit model, at this time the minimum equivalent resistance corresponding to the subcutaneous fluid change point becomes the dominant branch in the parallel circuit, and at this time the change of the voltage difference measured by the measurement electrode reflects the impedance change of the subcutaneous fluid change point, greatly reducing the interference of the surrounding biological tissue, thereby accurately determining the subcutaneous fluid change of the region to be detected. Through the design of the cage-shaped field formed by the excitation electrode pair, the problems of large measurement range and insufficient sensitivity in the related art are solved, which can focus on the impedance change of the subcutaneous fluid, and significantly improve the accuracy and reliability of the subcutaneous fluid change monitoring.

[0068] The subcutaneous fluid change monitoring device provided by the present application arranges the excitation electrode pair and the measurement electrode pair on the electrode patch in a specific manner, so that after the device is started, the excitation signal applied by the device forms a cage-shaped field to force the current to flow through the target object to be detected. The region avoids the problem that the current spreads to the surrounding tissue, resulting in a large measurement range, low sensitivity, and inaccurate measurement. The measurement electrode pair is arranged according to the position of the cage-shaped field to ensure that the measurement range is accurate and the signal sensitivity is optimal, can only respond to the impedance change caused by the subcutaneous fluid change in the region to be detected, avoids the interference of the surrounding tissue, and thus obtains accurate subcutaneous fluid change monitoring results, guarantees the accuracy and reliability of detecting the subcutaneous fluid change on the skin surface, provides a high-reliability hardware foundation for non-invasive subcutaneous fluid change monitoring, and realizes all-weather real-time monitoring of the subcutaneous fluid change by attaching the device to the skin, thereby providing a reference for doctors and patients in time, especially for postoperative monitoring or early subcutaneous fluid change warning in emergency scenes.

[0069] Further, the present application can also be optimized for medical instrument products using impedance measurement: integrated design of electrode patch and control unit to reduce the size of the device. The electrode patch can be designed to be ultra-thin so that the device can be worn on the skin like a plaster patch for a long time.

[0070] In some embodiments, the ratio of the first spacing of each excitation electrode pair 23 to the second spacing of the measurement electrode pair 22 satisfies a preset multiple range, the cage-shaped field is divided into a first half and a second half by the perpendicular bisector of the straight line corresponding to the first spacing, the positive end 221 of the measurement electrode pair and the positive end 231 of all excitation electrode pairs are distributed in the first half, and the negative end 222 of the measurement electrode pair and the negative end 232 of all excitation electrode pairs are distributed in the second half.

[0071] In the illustrated embodiment, as Figure 1 and Figure 6 As shown, each excitation electrode pair 23 includes a positive terminal 231 for applying an excitation signal F+ and a negative terminal 232 for applying an excitation signal F-. A first spacing is the distance between the positive terminal 231 and the negative terminal 232 of the excitation electrode pair 23, and a second spacing is the distance between the positive terminal 221 and the negative terminal 222 of the measurement electrode pair 22. The positive terminals 231 of all excitation electrode pairs 23 are located in the same half of the cage-like field and are interconnected by an electrical connection line 24, while the negative terminals 232 of all excitation electrode pairs 23 are located in the other half of the cage-like field and are interconnected by another electrical connection line 24.

[0072] In the embodiment shown, in terms of bioelectrical impedance detection, such as subcutaneous bleeding monitoring, due to the weak signal of impedance change transmitted to the skin surface in deep tissue, deep bleeding monitoring is more difficult and is easily covered by noise. Therefore, reasonable electrode sheet arrangement is particularly important for achieving high-precision non-invasive monitoring of subcutaneous bleeding on the skin surface. Deviation of the electrode sheet position can lead to inaccurate monitoring area, so a larger measurement range is required, but sufficient sensitivity needs to be maintained to avoid excessive measurement range leading to low sensitivity. In addition, bleeding detection requires comparison of impedance values before and after bleeding, and the current change before and after actual bleeding is not obvious and has large error, so signal resolution needs to be improved. The present application adopts a four-electrode method and designs a reasonable electrode sheet arrangement, which can effectively solve the problems of insufficient sensitivity, range and resolution in skin surface monitoring. The four-electrode method is F+, F-, S+ and S-. The excitation electrode pair 23 is the outer electrode, which applies a preset frequency excitation signal sine wave after starting the device each time. The preset frequency can be 50 kHz. The measurement electrode pair 22 is the inner electrode, which collects the voltage difference between the two points to reflect the impedance change of the area to be detected. When the first distance of the excitation electrode pair is too far, the voltage difference change obtained by the measurement electrode pair is small. In order to improve the signal resolution, the first distance should be appropriately reduced. Through design and verification, when the ratio of the first distance to the second distance meets the preset multiple range, the electric field strength of the area to be detected can be effectively enhanced, and the signal resolution can be improved. When the distance between the positive terminal 221 and the negative terminal 222 of the measurement electrode pair 22, i.e. the second distance, is smaller, the electric field gradient is steeper, and the local impedance change is more sensitive, but the measurement range is limited and only covers a shallow or small monitoring area. In order to improve the accuracy of the bleeding monitoring area, the second distance should be appropriately increased. Through design and verification, when the second distance meets the distance range shown in Table 1, the monitoring area can be ensured to be accurate and the sensitivity can be maintained. The current change before and after actual bleeding is very small, and the voltage difference change of the measurement electrode pair 22 is large, so in order to improve the signal quality, the voltage difference change can be monitored instead of the impedance change. The first distance range of the excitation electrode pair 23 and the second distance range of the measurement electrode pair 22 are shown in Table 1. As shown in Table 1, in some preferred embodiments, the first distance range is 4-20 cm, the second distance range is 2-14 cm, and the preset multiple range is [1.4, 2].

[0073] Table 1

[0074]

[0075] The subcutaneous effusion change monitoring device provided by the present application arranges each electrode sheet in a specific array manner, which can realize high sensitivity, wide range coverage and high resolution of deep subcutaneous effusion change monitoring on the skin surface, and significantly improve the reliability of the monitoring result.

[0076] In some embodiments, the control unit 1 further includes a microprocessor configured to: convert the current flowing through the measuring electrode pair 22 into a second voltage difference; acquire the first voltage difference and the second voltage difference; perform discrete Fourier transform processing on the acquired data to obtain a target voltage value and a target current value; determine the voltage amplitude and current amplitude based on the target voltage value and the target current value; and obtain the impedance value based on the voltage amplitude and the current amplitude.

[0077] In the illustrated embodiment, as Figure 4 As shown, after the device is powered on, an AC excitation signal of known frequency and amplitude can be applied to the unknown impedance through the excitation electrode. The current flowing through the potential subcutaneous effusion change point and the voltage difference (i.e., the first voltage value) at the potential subcutaneous effusion change point are measured through the measuring electrode. The microprocessor includes a TIA (trans-impedance amplifier), an ADC (digital-to-analog converter), and a digital filter. The TIA converts the current at the potential subcutaneous effusion change point into a voltage that can be measured by the ADC, i.e., the second voltage difference. The ADC samples the first and second voltage differences to obtain discrete time series data, and performs a Discrete Fourier Transform (DFT) on each discrete time series data. The DFT is performed based on the time series data corresponding to the first voltage difference to calculate the target voltage value, and the DFT is performed based on the time series data corresponding to the second voltage difference to calculate the target current value. Because the DFT can decompose data into sine and cosine components of different frequencies, the resulting target voltage and current values ​​are complex numbers containing both real and imaginary parts. These values ​​describe the amplitude and phase of the measured signal. Therefore, the voltage and current amplitudes can be obtained by extracting the real and imaginary parts from the target voltage and current values. Based on these amplitudes, the voltage and current at the potential subcutaneous effusion change point can be calculated. Combining the voltage and current at the potential subcutaneous effusion change point with the following formula, the impedance value can be calculated:

[0078]

[0079] in, It is the impedance value. It is the voltage at the potential subcutaneous fluid change point. It is the current at potential subcutaneous fluid change points. This is the value of the high-speed TIA gain resistor, in Ω.

[0080] In the illustrated embodiment, vascular injury causes interstitial fluid (such as blood) to flow into the interstitial space, increasing local conductivity and consequently decreasing impedance. The digital filter continuously calculates the trend of impedance changes to monitor subcutaneous fluid accumulation and promptly trigger appropriate alarm levels.

[0081] The subcutaneous fluid change monitoring device provided by this invention is based on the characteristic that the impedance value changes with the amount of subcutaneous fluid. It performs non-invasive monitoring of subcutaneous fluid changes on the skin epidermis. It can be used to monitor subcutaneous fluid changes in internal organs and deep tissue injuries. It can provide real-time monitoring data around the clock, providing reference for doctors and users.

[0082] Taking subcutaneous hemorrhage monitoring as an example, such as Figure 5 As shown, when using impedance changes to monitor subcutaneous bleeding, multiple criteria are needed to distinguish between bleeding and non-bleeding to improve the accuracy of monitoring data and reduce false alarms. These criteria include the following four points:

[0083] (1) Impedance drop rate. For example... Figure 5 As shown in Figure A, by calculating the slope of the impedance value change over time, slow bleeding, acute bleeding, and interference can be distinguished. Only when the impedance drop rate slope is within a certain range, such as 3-40% / min, is it likely the bleeding condition to be monitored, i.e., slow bleeding. If the impedance value changes too rapidly, it is either acute bleeding, which can be manually determined, or interference. If the impedance value changes too slowly, it may be due to changes in electrode contact impedance or baseline drift caused by temperature, and is not actual bleeding.

[0084] (2) Impedance change amplitude and rate of change. For example... Figure 5 As shown in Figure B, impedance fluctuations caused by body movement, contact impedance changes, etc., are eliminated by calculating the ratio and absolute value of impedance before and after bleeding. A ratio and absolute value of impedance before and after bleeding within a certain range, such as 2-10%, is likely indicative of the bleeding condition to be monitored. An excessively low impedance change may indicate interference from body movement or contact impedance changes.

[0085] (3) Duration of impedance change. For example... Figure 5 As shown in Figure C, by setting a time threshold for the duration of bleeding, short-term interference can be eliminated, and long-term impedance drift can be prevented from being misjudged as bleeding. Only when the duration of impedance change is within a certain range, such as 20 seconds to 30 minutes, can it be considered a bleeding situation to be monitored. If the duration of impedance change is too short, it may be due to interference such as body movement, and if the duration of impedance change is too long, it may not be human bleeding.

[0086] (4) Complexity of the impedance drop curve. For example... Figure 5 As shown in Figure D, the kurtosis and sample entropy of the impedance drop curve are calculated to determine whether it conforms to a typical bleeding pattern. In actual clinical practice, the bleeding rate is affected by internal blood pressure, external pressure, and increased hematoma pressure after bleeding. Only when the complexity of blood pressure changes within a certain range, such as a kurtosis of 2-30 and a sample size of 0.2-0.8, can it be considered a bleeding situation that needs to be monitored.

[0087] For the above determination conditions, four types of features are used to predict bleeding and non-bleeding, including impedance drop slope, impedance drop area, impedance drop depth, and impedance drop complexity. Combined with machine learning algorithms, a pre-training model is constructed. Machine learning algorithms include but are not limited to support vector machine SVM, adboost, etc. The model modelV is obtained by training.

[0088] The preparation process of the pre-training model is described as follows:

[0089] Step 1, data collection. Collect bioimpedance data under different conditions, such as animal experiments, simulation tooling and clinical simulation data, etc. The data is sliced into impedance data segments of subcutaneous fluid changes and non-subcutaneous fluid changes for a preset time length, such as 3 minutes;

[0090] Step 2, data standardization. Two time windows are used for data standardization processing to eliminate individual differences. The data standardization processing formula is X2=W1*X / (W2*X), where X is the initial impedance data segment, X2 is the standardized impedance data segment, and W1 and W2 are window functions;

[0091] Step 3, data filtering. The impedance data segment obtained in step 2 is filtered by a preset filter function composed of a relaxation factor and a filtering threshold to eliminate impedance fluctuations caused by non-subcutaneous fluid changes. The preset filter function is X3=X2 / [1+k*exp(x2+C)], where X3 is the filtered impedance data segment, i.e. the processing result, k is the relaxation factor, and C is the filtering threshold, which is determined according to the impedance drop rate during the slowest subcutaneous fluid change;

[0092] Step 4, feature extraction. In a fixed time window (such as 3 minutes), six types of conditional features as shown in Table 2 are extracted;

[0093] Step 5, machine learning modeling. The conditional features extracted in step 4 are used as model inputs, and SVM, Adaboost, etc. are used to train the model for subcutaneous fluid change determination to obtain the final subcutaneous fluid change discrimination model ModelV, i.e. the pre-training model.

[0094] Table 2

[0095]

[0096] After obtaining the pre-trained model, the impedance values monitored in real time by the control unit 1 are used to determine the subcutaneous fluid change. Due to the different body compositions and skin contact impedances of different human bodies, the calculated impedance values need to be calibrated, i.e., the standardization and data filtering processes in the above-mentioned second to third steps. The target condition features of the real-time impedance values are extracted through the above-mentioned fourth step. The target condition features are input into the pre-trained model to obtain the subcutaneous fluid change probability. When the subcutaneous fluid change probability reaches a preset probability (such as 95%), the real-time subcutaneous fluid change determination result is subcutaneous fluid change, and otherwise, it is non-subcutaneous fluid change.

[0097] The subcutaneous fluid change monitoring device provided by the present application can determine the subcutaneous fluid change and non-subcutaneous fluid change by analyzing the impedance values through the calibration unit, and can solve the problem of high false alarm rate of traditional single threshold method by combining multi-dimensional feature extraction and machine learning classification algorithm. The device can dynamically capture the spatiotemporal characteristics of impedance changes, distinguish real subcutaneous fluid changes from interference events, and improve the accuracy and reliability of the device monitoring.

[0098] In the illustrated embodiment, the control unit 1 further includes an alarm state indicator light 3 and a buzzer 4 communicatively connected with the calibration unit. The alarm state indicator light 3 is used to trigger light consistent with the alarm indication level according to the alarm indication of the calibration unit, and the buzzer 4 is used to trigger sound effects consistent with the alarm indication level according to the alarm indication of the calibration unit. The calibration unit is further configured to determine whether the falling rate reaches a first threshold value; if the falling rate reaches the first threshold value, trigger a first-level alarm indication, and take the current calibrated impedance value as a reference impedance value, and continue to monitor the change percentage of the calibrated impedance value compared with the reference impedance value; if the change percentage reaches a first preset percentage, trigger a second-level alarm indication, and if the change percentage reaches a second preset percentage lower than the first preset percentage, trigger a third-level alarm indication.

[0099] In the embodiment shown, after the device is powered on, the control unit 1 performs a series of self-tests to ensure normal function. Then the microprocessor is started to monitor the subcutaneous fluid changes, which uses a digital filter to collect, convert and calculate the changes in bioimpedance values, and calibrates the calculation results through the calibration unit. If the real-time subcutaneous fluid change determination result of the calibration unit is subcutaneous fluid change, the rate of impedance value decrease is continuously monitored, and it is determined whether the rate of impedance value decrease reaches a specified slope threshold, i.e. the first threshold, such as 3% / min. The first threshold satisfies the range of 3~40% / min, and can be set according to actual application. When the rate of impedance value decrease reaches the first threshold, the calibration unit will trigger a first alarm indication, and save the impedance value at this time as a reference for measuring the subcutaneous fluid change process, i.e. the reference impedance value. If the subcutaneous fluid change continues to develop, the impedance value continues to decrease, and decreases by more than a first preset percentage, such as 85%, relative to the reference impedance value, a second alarm indication will be triggered. Further, if the subcutaneous fluid change continues to develop, and decreases by more than a second preset percentage, such as 70%, relative to the reference impedance value, a third alarm indication will be triggered.

[0100] In the embodiment shown, the alarm status indicator light 3 can be a 3-level LED indicator light. As shown, the alarm status indicator light 3 and the buzzer 4 are respectively in communication connection with the microprocessor, according to the first alarm indication of the microprocessor, a first audible and visual alarm is triggered, according to the second alarm indication of the microprocessor, a second audible and visual alarm which is more intense than the first audible and visual alarm is triggered, and according to the third alarm indication of the microprocessor, a third audible and visual alarm with the highest intensity is triggered. Figure 2

[0101] The subcutaneous fluid change monitoring device provided by the application uses real-time data analysis and combines graded alarms to achieve rapid alarm for different severity of subcutaneous fluid changes.

[0102] In some embodiments, a second electrode patch is also included. In one implementation, the structure of the second electrode patch is the same as that of the electrode patch 2 and the range of the cage-shaped field formed is also the same. The second electrode patch can replace the electrode patch 2 and be detachably connected with the control unit 1. In another implementation, the structure of the second electrode patch is the same as that of the electrode patch 2, but the range of the cage-shaped field formed can be different.

[0103] ​In the embodiment shown, the electrode patch 2 is arranged as a detachable module, and the user can freely replace the electrode patch with different electrode spacing according to the monitoring requirements (such as the detection depth and the size of the area to be detected). By replacing the electrode patch 2 to adjust the first spacing of the excitation electrode pair 23 and the second spacing of the measurement electrode pair 22, the electric field distribution and signal quality in different monitoring scenarios can be optimized. The subcutaneous fluid change monitoring device in this embodiment solves the problem that the traditional fixed electrode subcutaneous fluid change monitoring device cannot be adjusted to adapt to diversified detection scenarios once it is produced.

[0104] In some embodiments, the control unit 1 further comprises a three-axis acceleration sensor 5, which is in communication connection with the calibration unit, for measuring the pitch angle information of the target object and sending it to the calibration unit, so that the calibration unit calibrates the impedance value according to the pitch angle.

[0105] In the embodiment shown, different postures of the human body can cause different electrode pressures, affecting impedance measurement. By adding a three-axis acceleration sensor 5 in the control unit 1, the wearer's body movement can be sensed in real time, and the impedance value can be calibrated by the calibration unit to improve the accuracy of determining the subcutaneous fluid change, and more accurate results of subcutaneous fluid change monitoring can be given. The three-axis acceleration sensor 5 measures the pitch angle of the wearer in combination with a specific algorithm such as an activity amount calculation algorithm to calibrate the impedance value, thereby reducing false triggering of the device caused by body movement.

[0106] The subcutaneous fluid change monitoring device provided by the present application can effectively improve the reliability of subcutaneous fluid change monitoring through the acceleration sensor 5, help to distinguish between real subcutaneous fluid changes and body movement interference, achieve more accurate medical monitoring, and improve early monitoring and early warning capabilities.

[0107] In some embodiments, the sheet-shaped carrier 21 comprises a flexible and breathable material with a thickness ranging from 1 to 5 mm.

[0108] In some embodiments, as shown in Figure 6 At least two pairs of excitation electrode pairs 23 include a first excitation electrode pair and a second excitation electrode pair, which are installed in parallel on the upper surface of the sheet-shaped carrier 21. The measurement electrode pair 22 is installed at a position equally spaced from the first excitation electrode pair and the second excitation electrode pair on the upper surface of the sheet-shaped carrier 21, and the midpoint of the connection line of the measurement electrode pair 22, the midpoint of the connection line of the first excitation electrode pair, and the midpoint of the connection line of the second excitation electrode pair are located on the same straight line.

[0109] In some embodiments, the control unit 1 further comprises a lithium battery 6 and a battery pull tab 7 connected to each other. The lithium battery 6 is used to provide power, and the battery pull tab 7 is used to control the on-off of the power supply.

[0110] The subcutaneous effusion change monitoring device provided by the application provides long-time stable power supply support, so that the device can operate independently without external power supply connection, improves portability, can conveniently control the power switch, reduces battery consumption, is ready at any time, and improves use flexibility.

[0111] In some embodiments, the control unit 1 further comprises a state indication lamp 8, a reset button 9 and a potentiometer calibration button 10. The state indication lamp 8 is used to indicate the running state of the device, and the running state includes a normal running state, a standby state and an abnormal state. The reset button 9 is used to restore the device in the abnormal state to the initial state. The potentiometer calibration button 10 is triggered by external force to trigger a calibration program to calibrate the impedance value.

[0112] In the illustrated embodiment, the state indication lamp 8 enables the wearer or medical staff to quickly understand the device condition, avoiding misjudgment caused by device failure or abnormal operation. The normal running state is a state in which the excitation electrode pair can apply an alternating excitation electrode and the measurement electrode pair can measure an electrical signal. The standby state is a low-power state when the device is powered on and does not perform any measurement or operation. The abnormal state is a state in which the alternating excitation signal cannot be output or the output signal is unstable, or the response electrical signal generated by the excitation signal cannot be accurately measured, or the alarm is triggered by mistake. The reset button 9 manually restores the device to the initial state when the device is abnormal, ensuring that the device can quickly return to normal operation and ensuring device stability and maintainability. The initial state is a state in which the device is powered on and no alternating excitation electrode is applied and no electrical signal is collected. The calibration program includes the aforementioned calibration operation or common calibration algorithm, ensuring the consistency of subcutaneous effusion change monitoring in different individuals and different environments, and reducing false positives and false negatives.

[0113] The subcutaneous effusion change monitoring device provided by the application is optimized for medical instrument products using impedance measurement, achieving non-invasive and all-weather real-time monitoring of subcutaneous effusion changes, and providing accurate and reliable references for doctors and patients in a timely manner.

[0114] Based on the same inventive concept, according to another aspect of the application, as Figure 7 indicated, the embodiments of the application also provide an impedance value measurement method, specifically including the following steps:

[0115] Step S100, applying an excitation signal of a predetermined frequency to a target object through at least two pairs of excitation electrodes 23 to form a cage-shaped field domain containing a beam of equipotential lines in a region to be monitored of the target object;

[0116] Step S200, measuring a first voltage difference through a measurement electrode pair 22 located at the central position of the cage-shaped field domain and having a center line perpendicular to the beam of equipotential lines;

[0117] In step S300, the impedance value of the region to be monitored is determined according to the first voltage difference.

[0118] The impedance value measurement method of the present application, by arranging the excitation electrode pair and the measurement electrode pair in a specific manner, makes the excitation signal applied by the excitation electrode pair form a cage-shaped field in the detection region of the target object, so that the current only flows through the detection region, avoiding the problem of overlarge measurement range, low sensitivity and inaccurate measurement caused by the diffusion of current to the surrounding tissue. The measurement electrode pair is arranged according to the position where the cage-shaped field is formed to ensure that the measurement range is accurate and the signal sensitivity is optimal, and the voltage difference measured by the measurement electrode pair can accurately reflect the impedance change caused by the change of subcutaneous hydrops in the detection region, avoiding the interference of the surrounding tissue to calculate the accurate impedance value, providing a highly reliable solution for non-invasive subcutaneous hydrops monitoring. The technology can be used in the detection of subcutaneous hydrops on the skin surface, and timely provides a reference for doctors and patients.

[0119] The above is the exemplary embodiment disclosed by the present application, and the sequence of the above-mentioned embodiments disclosed by the present application is only for description, not representing the advantages and disadvantages of the embodiments. However, it should be noted that the above discussion of any embodiment is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples, and various changes and modifications can be made without departing from the scope defined by the claims. In addition, although the elements disclosed in the embodiments of the present application can be described or claimed in singular form, they can also be understood as plural unless explicitly limited to singular.

[0120] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples; under the idea of the embodiments of the present application, the technical features of the above embodiments or different embodiments can also be combined, and there are many other changes of different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principles of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A subcutaneous fluid accumulation change monitoring device, characterized by, The application relates to a subcutaneous effusion change monitoring device, which comprises the following components: a control unit (1); an electrode patch (2) detachably connected with the control unit (1), wherein the electrode patch (2) comprises a sheet-shaped carrier (21) and an electrode sheet, the upper surface of the sheet-shaped carrier (21) is provided with electrode points for mounting the electrode sheet, and the lower surface of the sheet-shaped carrier (21) is provided with a sticking layer for sticking to a target object; wherein the electrode sheet comprises a measuring electrode pair (22) and at least two pairs of parallelly arranged excitation electrode pairs (23), the at least two pairs of excitation electrode pairs (23) are used for applying excitation signals of a preset frequency to form a cage-shaped field region containing a bundle of equipotential lines, the connecting line of the measuring electrode pair (22) is perpendicular to the bundle of equipotential lines and is located at the central position of the cage-shaped field region, and is used for measuring a first voltage difference of the cage-shaped field region; the control unit is configured to: provide power to the excitation electrode pairs (23) to form the cage-shaped field region in a to-be-monitored area of the target object; control the measuring electrode pair (22) to measure the first voltage difference to obtain an impedance value of the to-be-monitored area, and determine a subcutaneous effusion change monitoring result according to the change of the impedance value.

2. The subcutaneous fluid collection change monitoring device of claim 1, wherein, The ratio of the first spacing of each excitation electrode pair to the second spacing of the measuring electrode pair satisfies a preset multiple range, the cage-shaped field region is divided into a first half and a second half by the perpendicular bisector of the straight line corresponding to the first spacing, the positive terminal (221) of the measuring electrode pair and the positive terminals (231) of all the excitation electrode pairs are distributed in the first half, and the negative terminal (222) of the measuring electrode pair and the negative terminals (232) of all the excitation electrode pairs are distributed in the second half.

3. The subcutaneous fluid collection change monitoring device of claim 1, wherein, The control unit (1) further comprises a calibration unit, and the calibration unit is configured to: collect the impedance value and perform standardization processing thereon, perform data filtering processing on the standardized impedance value based on a preset filtering function, and take the processing result as a calibrated impedance value; extract a target condition feature based on the calibrated impedance value, input the target condition feature into a pre-trained model, obtain a probability of subcutaneous effusion change, and judge whether the probability of subcutaneous effusion change reaches a preset probability; in response to the probability of subcutaneous effusion change reaching the preset probability, monitor the descending rate of the calibrated impedance value, and determine a subcutaneous effusion change monitoring result of the to-be-monitored area according to the descending rate; wherein the target condition feature comprises a width feature, an area feature, a depth feature, a kurtosis feature, a distribution graph feature and a complexity feature.

4. The subcutaneous fluid collection change monitoring device of claim 1, wherein, The application further comprises a second electrode patch which is identical in structure to the electrode patch (2) and has a cage-shaped field region range identical to or different from that of the electrode patch (2), and the second electrode patch can be detachably connected with the control unit (1) to replace the electrode patch (2).

5. The subcutaneous fluid collection change monitoring device of claim 1, wherein, The control unit (1) further comprises a microprocessor, and the microprocessor is configured to: convert the current flowing through the measuring electrode pair (22) into a second voltage difference, collect the first voltage difference and the second voltage difference, and perform discrete Fourier transform processing on the collected data to obtain a target voltage value and a target current value; determining a voltage amplitude and a current amplitude based on the target voltage value and the target current value; obtaining the impedance value based on the voltage amplitude and the current amplitude.

6. The subcutaneous fluid collection change monitoring device of claim 3, wherein, The control unit (1) further comprises an alarm state indicator light (3) and a buzzer (4) in communication connection with the calibration unit respectively, the alarm state indicator light (3) is used to trigger the light consistent with the alarm indication level according to the alarm indication of the calibration unit, and the buzzer (4) is used to trigger the sound effect consistent with the alarm indication level according to the alarm indication of the calibration unit; The calibration unit is further configured to: determine whether the falling rate reaches a first threshold value; if the falling rate reaches the first threshold value, trigger a first-level alarm indication, and take the current calibrated impedance value as a reference impedance value, and continue to monitor the change percentage of the calibrated impedance value compared with the reference impedance value; if the change percentage reaches a first preset percentage, trigger a second-level alarm indication, and if the change percentage reaches a second preset percentage lower than the first preset percentage, trigger a third-level alarm indication.

7. The subcutaneous fluid collection change monitoring device of claim 3, wherein, The control unit (1) further comprises a three-axis acceleration sensor (5) in communication connection with the calibration unit, which is used to measure the pitch angle information of the target object and send it to the calibration unit, so that the calibration unit calibrates the impedance value according to the pitch angle.

8. The subcutaneous fluid collection change monitoring device of claim 1, wherein, The sheet-shaped carrier (21) comprises a flexible and breathable material with a thickness ranging from 1 to 5 mm.

9. The subcutaneous fluid collection change monitoring apparatus of claim 1, wherein, The at least two pairs of excitation electrode pairs (23) comprise a first excitation electrode pair and a second excitation electrode pair, which are installed in parallel on the upper surface of the sheet-shaped carrier (21), and the measurement electrode pair (22) is installed at a position equally spaced from the first excitation electrode pair and the second excitation electrode pair on the upper surface of the sheet-shaped carrier (21), and the midpoint of the connection line of the measurement electrode pair (22), the midpoint of the connection line of the first excitation electrode pair and the midpoint of the connection line of the second excitation electrode pair are located on the same straight line.

10. An impedance value measurement method characterized by, It comprises: applying a preset frequency excitation signal to the target object through at least two pairs of excitation electrode pairs (23) to form a cage-shaped field containing a bundle of equipotential lines in the target object's to-be-monitored region; measuring a first voltage difference through a measurement electrode pair (22) located at the central position of the cage-shaped field and with the center connection line perpendicular to the bundle of equipotential lines; determining the impedance value of the to-be-monitored region according to the first voltage difference.

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