A fish biological impedance detection device based on multi-frequency four-electrode

Abstract

The utility model discloses a kind of fish biological impedance detection devices based on multi-frequency four electrodes, belong to aquatic product detection technical field.The device integrated detection block, handle and display block, inside is equipped with central processing unit and electronic system module.Through the four-electrode contact system of detection block bottom to fish body and detect voltage signal, combine the multi-frequency signal generation, noise filtering and impedance value conversion function of electronic system module, realize high-precision biological impedance measurement.Central processing unit passes through intelligent algorithm analysis impedance data, real-time output fish freshness value, fat content and freeze-thaw state etc. Index, result is visualized by display unit and presents.This device integrates portable design, multi-frequency four-electrode anti-interference technology and cloud data matching capability, suitable for aquatic processing and circulation link on-site rapid detection.

Description

Technical Field

[0001] This utility model relates to the field of aquatic product testing technology, specifically to a fish bioimpedance detection device based on a multi-frequency four-electrode system. Background Technology

[0002] The freshness, fat content, and freeze-thaw state of aquatic products are key indicators determining their quality, food safety, and economic value. Traditional testing methods, such as sensory evaluation, are highly subjective and difficult to quantify; microbiological testing is time-consuming (usually requiring more than 48 hours), failing to meet the need for rapid on-site assessment; while chemical analysis methods are highly accurate, they are complex to operate and require specialized instruments, reagents, and sample pretreatment, also making on-site real-time testing difficult. For fat content, conventional methods (Soxhlet extraction) damage the sample and are time-consuming; the determination of freeze-thaw state often relies on sensory evaluation or simple temperature measurements, which have limited accuracy and cannot identify microscopic changes.

[0003] In recent years, bioimpedance technology has shown promise in the field of food quality assessment due to its rapid, non-destructive, and objectively measurable characteristics. This technology applies a weak alternating current to biological tissues and measures their impedance (including impedance amplitude and phase angle) to reflect physiological information such as internal tissue structure, water distribution, and cell membrane integrity. Fish mortality and putrefaction are accompanied by significant bioelectrochemical changes, such as gradual cell rupture leading to intracellular fluid outflow and accumulation of adenosine triphosphate (ATP) degradation products (directly related to freshness K-value); the dielectric properties of adipose tissue differ from those of muscle tissue; and freeze-thaw cycles cause cell membrane rupture, fluid loss, and ice crystal formation, altering conductivity. Theoretically, analyzing the multi-frequency impedance response of fish tissues can reveal their freshness (e.g., K-value), fat percentage, and whether they have undergone freeze-thaw cycles.

[0004] The publicly disclosed technology CN221308181U is an impedance detection conduit capable of impedance detection; however, its application in fish bioimpedance analysis has room for improvement. Existing bioimpedance analysis techniques face several key bottlenecks when applied to rapid on-site testing of aquatic products, especially fish: contact resistance, electrode polarization effects, and background noise in aquatic trading environments (humid, saline) severely impact the accuracy and repeatability of single-frequency or two-electrode measurements. Information dimensions are insufficient; single-frequency impedance information cannot fully reflect the complex dielectric relaxation characteristics of tissues, and cannot effectively distinguish and simultaneously assess multiple key indicators (freshness, fat content, freeze-thaw state). Equipment portability is poor; existing BIA equipment used in laboratories or research is often bulky and complex to operate, requiring professional personnel and relying on external power supplies and computing devices for data processing. This makes it difficult to integrate and adapt to on-site application scenarios such as aquatic markets, fishing vessels, and processing workshops where single-handed operation and rapid results are required.

[0005] Therefore, there is an urgent practical need and significant technical challenge in developing a portable handheld testing device that integrates multi-frequency excitation, anti-interference four-electrode measurement, intelligent algorithm analysis, and a fish species database to achieve rapid, accurate, and non-destructive on-site testing of key indicators such as freshness, fat content, and freeze-thaw status of aquatic products. This invention aims to overcome the shortcomings of the existing technology and provide such an innovative solution. Utility Model Content

[0006] This invention aims to provide a portable handheld detection device that uses multi-frequency four-electrode bioimpedance technology to achieve rapid and accurate on-site measurement of key indicators such as fish freshness, fat content, and freeze-thaw status.

[0007] A fish bioimpedance testing device based on a multi-frequency four-electrode system includes a housing, which mainly consists of a probe block, a handle, and a display block. An electrode contact system is embedded in the bottom of the probe block, and a display unit is located on the surface of the display block. A circuit board is housed inside the housing, on which a central processing unit (CPU) and an electronic system module are mounted. This device integrates electrode detection, data processing, and result display. The operator can hold the handle with one hand and bring the electrode contact system at the bottom of the probe block into contact with the fish to test its freshness using bioimpedance measurement. The CPU and electronic system module process the data and display the results on the display unit. The CPU is pre-installed with intelligent analysis algorithms and is responsible for controlling the entire measurement process, processing the impedance data transmitted by the electronic system module, and running a built-in or connected cloud-based fish database for data matching and analysis. Ultimately, it calculates key indicators such as the fish's freshness (K-value), fat content, and freeze-thaw status.

[0008] A fish bioimpedance detection device based on multi-frequency four electrodes, comprising an electronic system module, including:

[0009] A multi-frequency AC signal generator for generating current signals with a frequency of at least 2kHz;

[0010] Voltage saturation detection circuit is used to prevent measurement signal distortion;

[0011] The noise filtering module uses a differential amplifier circuit and a rectifier circuit to eliminate contact noise.

[0012] The electronic system module addresses the issues of multi-frequency signal generation, signal distortion suppression, and noise interference. The multi-frequency AC signal generator supports impedance characteristic analysis of fish tissue at different frequencies, increasing data dimensionality; the voltage saturation detection circuit prevents signal overload distortion caused by poor electrode contact, ensuring measurement accuracy; and the differential amplifier and rectifier circuits filter out conducted noise from the aquatic environment, improving the signal-to-noise ratio.

[0013] A fish bioimpedance detection device based on multi-frequency four electrodes, the electrode contact system comprising:

[0014] At least two current electrodes are connected to a multi-frequency AC signal generator to apply microampere-level AC current to the fish.

[0015] The same number of voltage electrodes as the current electrodes are used to connect to the noise filtering module to detect changes in the fish's impedance.

[0016] This device employs a four-electrode separation method (i.e., separation of current-driven and voltage-detection electrodes) to effectively avoid the influence of contact impedance on measurement results. The voltage electrode is connected to a noise filtering module for highly sensitive detection of the voltage signal generated by changes in bioimpedance in the fish. The current electrode applies a multi-frequency alternating current to the fish, while the voltage electrode is dedicated to detecting the voltage drop on the fish surface and is physically isolated from the current loop. The voltage electrode does not carry current; it only measures the potential difference, thus avoiding the influence of electrode-tissue contact impedance. After amplifying the voltage electrode signal, it is converted to DC by a rectifier circuit, and then the impedance value is calculated by the central processing unit.

[0017] A fish bioimpedance detection device based on a multi-frequency four-electrode configuration is disclosed. The current and voltage electrodes are detachable, and their surfaces are covered with a corrosion-resistant conductive coating. The detachable design facilitates replacement and maintenance, while the corrosion-resistant conductive coating ensures stability and measurement accuracy during long-term use in humid and saline environments.

[0018] A fish bioimpedance detection device based on a multi-frequency four-electrode circuit includes an electronic system module that further comprises an impedance conversion unit. This unit consists of an AD5933 impedance conversion chip and peripheral filtering circuitry. The input port is connected to the voltage electrodes to convert the raw signal detected by the voltage electrodes into a bioimpedance value. Directly converting the analog voltage signal into a digital impedance value simplifies the data processing chain. The dedicated AD5933 chip and filtering circuitry enable high-precision impedance magnitude / phase angle calculation, reducing the computational burden on the central processing unit. Hardware-level signal processing mitigates the risk of software algorithm errors and improves response speed.

[0019] A fish bioimpedance detection device based on a multi-frequency four-electrode circuit features a Type-C communication interface on its display panel for connecting to external devices. The Type-C interface expands the device's data exchange and power supply options, supports exporting detection results to computers / mobile phones, is compatible with remote analysis, and supports fast charging and reverse power supply.

[0020] A fish bioimpedance detection device based on a multi-frequency four-electrode system has a battery compartment on the back of the casing, which houses a battery. The battery powers the entire device.

[0021] A fish bioimpedance detection device based on a multi-frequency four-electrode circuit features an interactive button array on its handle surface, including a fish species selection button, a start measurement button, a power switch, and a menu navigation button. Users can select the fish species to be tested from a built-in database of various economically important fish species using the fish species selection button, ensuring the accuracy of the analysis model. The start measurement button triggers the measurement command, the power switch controls the device's on / off state, and the menu navigation button is used to access settings, historical data, or other function menus.

[0022] A fish bioimpedance detection device based on a multi-frequency four-electrode design features a handle with anti-slip texture. This enhances hand stability, adapts to slippery environments, prevents the device from slipping due to fish mucus or water stains, and ensures operational safety.

[0023] A fish bioimpedance detection device based on a multi-frequency four-electrode system is disclosed, with a display screen for real-time display of detection results. The display screen provides real-time visual presentation, intuitively displaying quantitative information such as freshness grade, fat percentage, and frozen storage label.

[0024] The advantages of this invention are as follows: By integrating multi-frequency four-electrode bioimpedance technology, an intelligent anti-interference electronic system, and a dedicated algorithm into a portable handheld device, it significantly improves the accuracy, convenience, and efficiency of on-site fish quality testing. The separate four-electrode design effectively eliminates the influence of contact impedance, while the combination of multi-frequency signal excitation and hardware-level noise filtering technology ensures high accuracy and stability in complex environments. A pre-set fish species database and intelligent algorithms enable one-stop rapid analysis of key indicators. The integrated, single-handed ergonomic design and intuitive LCD display make it ideal for immediate, non-destructive on-site testing in aquatic product markets, fishing boats, or laboratories. Attached Figure Description

[0025] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall device of this utility model;

[0027] Figure 2 This is a schematic diagram of the rear of the overall assembly of this utility model;

[0028] Figure 3 This is a flowchart of the measurement and testing process of this utility model;

[0029] Figure 4 The graph shows the change of fish body impedance under 2kHz and 100kHz currents with storage time according to this invention.

[0030] Figure 5 This is a line graph showing the fitting of K and C values ​​for the large yellow croaker of this invention.

[0031] Figure 6 This is a schematic diagram of the detector block in Embodiment 2 of this utility model;

[0032] Figure 7 The graph shows the relationship between impedance and fat content of large yellow croaker before freezing, under a 100kHz current condition.

[0033] Figure 8 This is a graph showing the relationship between impedance and fat content in frozen large yellow croaker under a 100kHz current condition.

[0034] Figure 9 This invention provides test data on the bioimpedance values ​​of multiple sets of unfrozen and frozen-thawed fish under a 2kHz current condition.

[0035] Figure 10 This is a schematic diagram of the needle-type, ball-type, and sheet-type electrode structures in Embodiment 2 of this utility model.

[0036] Figure descriptions: 1-Housing, 11-Detector block, 12-Handle, 13-Display block, 3-Shell, 4-Electrode contact system, 5-Display unit, 2-Central processing unit, 4a-Snap-in part, 41-Current electrode, 42-Voltage electrode, 13a-Type-C communication interface, 71-Fish species selection key, 72-Start measurement key, 73-Power switch, 74-Menu navigation key, 11a-Magnetic platform, 11b-Card slot. Detailed Implementation

[0037] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0038] The concepts involved in this application will first be described with reference to the accompanying drawings. It should be noted that the following descriptions of various concepts are only for the purpose of making the content of this application easier to understand and do not constitute a limitation on the scope of protection of this application; furthermore, the embodiments and features in the embodiments of this application can be combined with each other unless otherwise specified. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] Example 1:

[0040] See attached document Figure 1-3As shown, the operator presses the power switch 73 on the handle 12 to start the device, and the LCD display 5 shows the initial interface. "Large Yellow Croaker" is selected from the built-in database using the fish selection key 71. The electrode contact system 4 at the bottom of the probe block 11 is placed firmly against the lateral muscle of the fish (avoiding areas with damaged scales). The current electrode 41 injects a multi-frequency microcurrent (2kHz / 100kHz) into the fish, while the voltage electrode 42 simultaneously captures the impedance signal. The multi-frequency AC signal generator generates a 2kHz or 100kHz current. The voltage saturation detection circuit can dynamically adjust the current intensity to prevent signal distortion (e.g., interference from surface moisture). The noise filtering module eliminates contact point noise through differential amplification, and the original signal is converted into a digital impedance value by the AD5933 impedance conversion chip. The central processing unit compares the large yellow croaker impedance model in the cloud database and outputs the freshness K-value, fat content, and frozen storage label.

[0041] Regarding the algorithm for the freshness K-value, bioimpedance technology measures changes in electrical impedance by applying a small alternating current to the fish. Biological tissues (such as fish bodies) consist of cell membranes, intracellular fluid, and extracellular fluid, exhibiting both electrical and capacitive properties. After a fish dies, cell membranes gradually break down, and ATP (adenosine triphosphate) degrades, leading to changes in impedance. The K-value is used as an indicator of freshness, reflecting the degree of ATP degradation (K-value = (hypoxanthine + hypoxanthine nucleoside) / total ATP × 100%). See Appendix. Figure 4 As shown, in the early stage of cell storage (when the cell membrane is intact), the impedance at 2 kHz (Z value) is high, while in the later stage (when the membrane breaks down), the impedance drops sharply, and the impedance at 100 kHz remains stable. This phenomenon reflects an increase in the K value (decreased freshness) because ATP degradation accelerates cell damage.

[0042] The device defines the C value. , Figure 5 The negative correlation between the C value (Y-axis) and K value (X-axis) of large yellow croaker is shown. When the C value increases, the K value decreases, indicating that the C value can accurately map the degree of ATP degradation by changing impedance. The C value is calculated in real time using an AI algorithm through a cloud database (which stores fish species models; in this example, large yellow croaker is used as an example) and the freshness K value is inferred from it.

[0043] Regarding the principle of fat content detection, adipose tissue has poor electrical conductivity, and its content is strongly positively correlated with impedance. Under high-frequency current (generally greater than 50kHz), the current passes through fat cells, and based on fat prediction models, the fat content can be directly reflected. (See attached diagram.) Figure 7 and attached Figure 8 As shown, taking a high-frequency current of 100kHz as an example, the impedance value is measured by passing a high-frequency current through the circuit, the fish species and temperature parameters are input, and the fat content is obtained by calling the fitting curve of the fat prediction model.

[0044] Regarding the detection principle of freeze-thaw marking, the impedance value (Z-value) reflects the integrity of the cell membrane. The cell membranes of fresh fish are relatively intact, composed of a phospholipid bilayer, which has insulating and charge storage capabilities, thus exhibiting a high impedance value. Conversely, the cell membranes of thawed fish are damaged, resulting in a significantly lower impedance value. Low-frequency currents (2kHz) cannot penetrate intact cell membranes but can penetrate damaged cell membranes, thus being used to determine whether fish have undergone frozen storage. (Refer to...) Figure 9 As shown, the impedance values ​​of unfrozen and thawed fish at a 2kHz current differ greatly, and the measured impedance value can be used to detect whether the fish has been thawed.

[0045] Example 2:

[0046] See attached document Figure 10 As shown, optionally, a combination of a current electrode and a voltage electrode with a probe block is provided. The bottom of the probe block is provided with a magnetic platform 11a and a slot 11b. The top engaging portions of the current electrode 41 and the voltage electrode 42 extend into the slot 11b and are connected to the internal circuit. The top surfaces of the current electrode 41 and the voltage electrode 42 are coated with a magnetic material, which can be attracted to the magnetic platform 11a for easy disassembly. The current electrode 41 and the voltage electrode 42 are available in different lengths, and the bottom shapes are needle-type, ball-type, and plate-type, to suit fish of different shapes. For fish with extremely uneven surfaces, a needle-type electrode can be selected to adapt to different heights and fix the measurement point; for fish with a surface curvature close to a flat surface, a plate-type electrode can be selected to increase the contact area and improve the measurement accuracy; for fish with a relatively smooth surface curvature, a ball-type electrode can be selected to fit the curvature for easy fixation and measurement.

[0047] It should be noted that the terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit the scope of this application. As shown in this specification, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may include the plural. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element.

[0048] It should also be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "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 this application 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 a limitation on this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," "linked," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0049] The embodiments and / or implementation methods described above are merely preferred embodiments and / or implementation methods for implementing the present utility model, and are not intended to limit the implementation methods of the present utility model in any way. Any person skilled in the art can make some modifications or alterations to other equivalent embodiments without departing from the scope of the technical means disclosed in the present utility model, but these should still be regarded as the same technology or embodiment as the present utility model.

[0050] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of this application.

Claims

1. A fish bioimpedance detection device based on a multi-frequency four-electrode circuit, characterized in that, The device includes a housing (1), which is mainly composed of a probe block (11), a handle (12), and a display block (13). The probe block (11) is equipped with an electrode contact system (4) at its bottom, and the display block (13) is equipped with a display unit (5) on its surface. The housing (1) is equipped with a circuit board inside, and a central processing unit (2) and an electronic system module are fixed on the circuit board.

2. The fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The electronic system module includes: A multi-frequency AC signal generator for generating current signals with a frequency of at least 2kHz; Voltage saturation detection circuit is used to prevent measurement signal distortion; The noise filtering module uses a differential amplifier circuit and a rectifier circuit to eliminate contact noise.

3. The fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 2, characterized in that, The electrode contact system (4) includes: At least two current electrodes (41) are connected to a multi-frequency AC signal generator to apply microampere-level AC current to the fish body; The same number of voltage electrodes (42) as the current electrodes (41) are used to connect the noise filtering module to detect the fish body impedance change signal.

4. The fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 3, characterized in that, The current electrode (41) and voltage electrode (42) are detachable structures, and the surfaces of the current electrode (41) and voltage electrode (42) are covered with an anti-corrosion conductive coating.

5. A fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 3, characterized in that, The electronic system module also includes an impedance conversion unit, which consists of an AD5933 impedance conversion chip and an external filter circuit. The input port is connected to the voltage electrode (42). The impedance conversion unit is used to convert the original signal detected by the voltage electrode (42) into a bioimpedance value.

6. The fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The surface of the display block (13) is provided with a Type-C communication interface (13a) for connecting external devices.

7. A fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The back of the housing (1) is provided with a battery compartment, and the surface is provided with a compartment shell (3), which contains a battery.

8. A fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The handle (12) is provided with an interactive button group, including a fish species selection button (71), a start measurement button (72), a power switch (73), and a menu navigation button (74).

9. A fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The handle (12) has anti-slip texture on its surface.

10. A fish bioimpedance detection device based on a multi-frequency four-electrode according to claim 1, characterized in that, The display unit (5) is an LCD screen used to display the detection results in real time.

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