Portable bioelectrical impedance imaging system and method based on ad5940

Abstract

The portable bioelectric impedance imaging system and method based on AD5940 generates an alternating excitation signal by a signal conditioning and acquisition device, and under the unified control of a control and communication device, the measured object is injected after being selected by an electrode interface device; the measured object forms a current distribution field under the excitation, and generates a boundary response signal between the remaining electrodes; the response signal is returned to the signal conditioning and acquisition device through the electrode interface device, and after analog conditioning, analog-digital conversion and frequency domain operation, boundary electrical measurement data is obtained; the control and communication device sends the boundary electrical measurement data to an external terminal for processing and obtains an image. Based on the above overall structure, the multi-electrode time division multiplexing measurement device is designed uniformly at the system level, while ensuring the integration and portability of the device, the boundary excitation, the acquisition link and the imaging processing link are integrated and cooperated, so that the portable bioelectric impedance imaging system based on AD5940 has the advantages of smaller size and convenient carrying application.

Description

Technical Field

[0001] This application relates to the field of bioelectrical impedance measurement and electrical impedance imaging technology, specifically to a portable bioelectrical impedance imaging system and method based on AD5940. Background Technology

[0002] Electrical Impedance Tomography (EIT) is an imaging method based on the inversion of electric field distribution. Its basic principle is to arrange multiple electrodes on the surface of the target being measured, inject a weak alternating current into the electrodes, measure the corresponding boundary voltage response, and solve the conductivity distribution inside the target area by combining a mathematical model.

[0003] Currently, electrical impedance tomography (EIT) technology is widely used in biomedical testing, lung ventilation monitoring, and tissue condition assessment. However, traditional EIT systems use discrete components and multi-module structures, resulting in bulky equipment that is difficult to meet the needs of portable applications. Moreover, in multi-electrode measurements, electrode connections and data acquisition links are complex and susceptible to noise and inter-electrode interference, leading to poor measurement accuracy and stability.

[0004] Therefore, in the context of the development trend of wearable monitoring and portable medical devices, highly integrated, small-sized electrical impedance tomography devices suitable for portable scenarios are the shortcomings and bottlenecks of existing technologies. Summary of the Invention

[0005] In view of this, to address the problem of large size and inconvenience of carrying electrical impedance imaging, a portable bioelectrical impedance imaging system and method based on AD5940 is provided.

[0006] According to one aspect of the embodiments of this application, a portable bioelectrical impedance imaging system based on AD5940 is disclosed, including an electrode interface device, a signal conditioning and acquisition device, a control and communication device, and a power supply device, wherein: An electrode interface device for connecting to the object being measured; used to connect multiple measuring electrodes. The signal conditioning and acquisition device is electrically connected to the electrode interface device; it is used to output an AC voltage signal and convert it into a stable AC excitation signal through the signal conditioning circuit, and then send it to the electrode interface device, and receive the electrical response signal returned by the electrode interface device to obtain the boundary electrical measurement data of the object under test. The control and communication device is electrically connected to the electrode interface device and the signal conditioning and acquisition device, respectively; it is used to control electrode switching and acquisition timing, and output boundary electrical measurement data. The power supply unit is electrically connected to the electrode interface unit, the signal conditioning and acquisition unit, and the control and communication unit, respectively, to provide operating power to each unit; The AC voltage signal is converted into a stable AC excitation signal by the signal conditioning and acquisition device and then output to the electrode interface device and injected into the object under test. The obtained electrical response signal is returned by the electrode interface device to the signal conditioning and acquisition device for sampling and processing. The control and communication device controls the electrode switching and data acquisition and sends the boundary electrical measurement data to the external terminal for use in electrical impedance imaging.

[0007] According to one aspect of the embodiments of this application, a portable bioelectrical impedance imaging method based on AD5940 includes: The connection relationship of multiple electrodes is switched by an electrode interface device, so that one set of electrodes forms an excitation electrode pair and another set of electrodes forms a measurement electrode pair. The excitation signal is output by the signal conditioning and acquisition device and injected into the object under test through the electrode interface device; The boundary response signal of the object under test is obtained by measuring the electrode pair. The signal conditioning and acquisition device samples the boundary response signal and extracts its frequency domain features to obtain the boundary electrical measurement data at the target frequency. The electrode connection relationship is switched sequentially according to the preset combination of excitation and measurement, and the excitation and measurement process is repeated to obtain boundary electrical measurement data corresponding to multiple combinations of excitation and measurement. The boundary electrical measurement data is preprocessed and then input into the imaging processing module to obtain the conductivity distribution image of the target area.

[0008] The system and method of this embodiment first generate an AC excitation signal from the signal conditioning and acquisition device. Under the unified control of the control and communication device, the signal is injected into the object under test after being selected by the electrode interface device. Subsequently, the object under test forms a current distribution field under the excitation, generating boundary response signals between the remaining electrodes. This response signal is then returned to the signal conditioning and acquisition device through the electrode interface device. After analog conditioning, analog-to-digital conversion, and frequency domain calculation, boundary electrical measurement data at the target frequency is obtained. Afterward, the control and communication device sends the boundary electrical measurement data to an external terminal, where the data is preprocessed and the image is reconstructed to obtain an image of the conductivity distribution within the target area. Based on the above overall structural design, this invention unifies the design of the AD5940 analog front-end and the multi-electrode time-division multiplexing measurement device at the device level. This ensures both device integration and portability while integrating the boundary excitation, acquisition link, and imaging processing link. The resulting portable bioelectrical impedance imaging system based on the AD5940 has the advantages of smaller size and convenient portability.

[0009] Furthermore, through the collaborative design of highly stable front-end hardware acquisition and back-end joint reconstruction methods, the system's products can not only obtain reliable data, but also output conductivity distribution images with better boundary clarity and lower artifacts, thus forming a complete imaging closed loop.

[0010] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0011] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0012] The above and other objectives, features and advantages of this application will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0013] Figure 1 This is a schematic diagram of an electrical impedance imaging system provided according to an embodiment of this application.

[0014] Figure 2 It is based on Figure 1 A logic block diagram of the electrical impedance imaging system is shown in the corresponding embodiment.

[0015] Figure 3 It is based on Figure 1 A schematic diagram of the electrode interface device shown in the corresponding embodiment.

[0016] Figure 4 It is based on Figure 1 The corresponding embodiment shows the architecture diagram of the signal conditioning and acquisition device.

[0017] Figure 5 This is a diagram illustrating the internal structure of the AD5940 analog front end according to one embodiment.

[0018] Figure 6 It is based on Figure 1 The architecture diagram of the control and communication device shown in the corresponding embodiment.

[0019] Figure 7 It is based on Figure 1 A schematic diagram of the power supply device is shown in the corresponding embodiment.

[0020] Figure 8 This is a flowchart of a portable bioelectrical impedance imaging method based on AD5940. Detailed Implementation

[0021] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided to make the description of this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0022] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details are provided in the following description to give a full understanding of exemplary embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced with one or more of the specific details omitted, or other methods, components, steps, etc., can be employed. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0023] Combined with appendix Figures 1-2 , Figure 1 This is a diagram of the electrical impedance imaging system architecture. Figure 2 This is a logic block diagram of an electrical impedance imaging system. The portable bioelectrical impedance imaging system based on the AD5940 includes an electrode interface device, a signal conditioning and acquisition device, a control and communication device, and a power supply device, wherein: An electrode interface device connects to the object under test and is used to connect multiple measuring electrodes. Specifically, the electrode interface device connects multiple measuring electrodes and establishes reconfigurable connections between the electrodes and the excitation and measurement paths under the action of control signals. Then, it is attached to the surface of the object under test, such as the skin of the human body.

[0024] The signal conditioning and acquisition device is electrically connected to the electrode interface device. It outputs an AC voltage signal, which is then converted into a stable AC excitation signal by a signal conditioning circuit and transmitted to the electrode interface device. It also receives the electrical response signal returned by the electrode interface device to acquire the boundary electrical measurement data of the object under test. Specifically, the signal conditioning and acquisition device outputs the excitation signal and receives the boundary response signal through the electrode interface device. It then conditions, samples, and extracts frequency domain features from the response signal to form the boundary electrical measurement data.

[0025] Control and communication device; the control and communication device is connected to the electrode interface device and the signal conditioning and acquisition device respectively, and is used to control electrode switching and acquisition timing, and output boundary electrical measurement data.

[0026] Power supply unit; The power supply unit is electrically connected to the electrode interface unit, the signal conditioning and acquisition unit and the control and communication unit respectively, and is used to provide working power to each unit.

[0027] The AC voltage signal is output as an AC excitation signal by the signal conditioning and acquisition device and then injected into the object under test by the electrode interface device. The obtained response signal is returned by the electrode interface device to the signal conditioning and acquisition device for sampling and processing. The control and communication device controls the electrode switching and data acquisition and sends the boundary electrical measurement data to the external terminal for use in electrical impedance imaging.

[0028] Based on the aforementioned portable bioelectrical impedance imaging system, this design integrates the electrode interface device, signal conditioning and acquisition device, control and communication device, and power supply into a single structure. Power is supplied by the power supply. The signal conditioning and acquisition device outputs excitation signals and receives response feedback through the electrode interface device. The control and communication device then controls electrode switching and acquisition timing, outputting boundary electrical measurement data to support impedance imaging. This allows the previously dispersed measurement, control, communication, and power supply functions to form a closed loop within the same system framework. This facilitates system integration and a compact layout of the devices, reduces reliance on external functional modules, and ultimately reduces the size of the bioelectrical impedance imaging system. A smaller bioelectrical impedance imaging system is more portable and easier to use.

[0029] In one embodiment, combined with the appendix Figure 3 , Figure 3 This is a schematic diagram of an electrode interface device, which includes an electrode array and a multiplexing module. The electrode array includes multiple electrodes arranged at the boundary of the object under test; one end of the multiplexing module is connected to the multiple electrodes, and the other end is connected to a signal conditioning and acquisition device. The control and communication device is connected to the multiplexing module to control some of the electrodes to form an excitation injection path, another part of the electrodes to form a measurement path, and the remaining electrodes to be in an open or high-resistance state.

[0030] Specifically, multiple electrodes are evenly distributed in a ring along the boundary of the object being measured, ensuring that the current injection path and boundary voltage acquisition path cover the circumferential area of ​​the target region. In applications involving human detection, the electrodes are preferably deployed using a flexible attachment method to enhance adaptability to curved or deformable surfaces of the human body. Furthermore, a conductive dielectric layer can be placed between the electrodes and the measured surface to improve electrode contact, reduce the impact of contact impedance variations on measurement results, and thus improve the consistency and stability of boundary voltage acquisition. This structural design is particularly suitable for human posture recognition, tissue condition sensing, and other biomedical detection scenarios.

[0031] One end of the multiplexing module is connected to multiple electrodes, and the other end is connected to the excitation output and response input terminals of the signal conditioning and acquisition system. The main controller (such as an MCU) in the control and communication device is electrically connected to the multiplexing module to control the conduction state of each channel. Through this device, at any given measurement moment, one set of electrodes can form an excitation electrode pair, another set can form a measurement electrode pair, and the remaining electrodes can be in an open or high-impedance isolated state. This establishes a measurement topology of "current excitation path, current measurement path, and isolation of the remaining electrodes" at the hardware level, which helps suppress parasitic current paths and inter-electrode coupling interference, improving the accuracy of excitation injection and response acquisition.

[0032] The multi-channel selection module employs a parallel mapping structure composed of multiple analog switches. Specifically, ports with the same number in the multiple analog switches are connected to the same electrode node, enabling each electrode to form a unified mapping relationship with both the excitation and measurement paths. With this structural design, each electrode only needs to have one set of lines led out to dynamically switch between its excitation and measurement roles. This simplifies the originally complex multi-channel wiring relationship to a finite number of electrode leads, effectively simplifying wiring, reducing hardware complexity, and minimizing differences between channels. This design significantly reduces the number of connections while maintaining full functionality, contributing to a more compact overall structure and making it more suitable for portable devices.

[0033] Furthermore, the electrode leads are designed with equal lengths to ensure that each channel maintains as consistent an electrical characteristic as possible during transmission. This reduces phase deviation, amplitude error, and inconsistencies in parasitic parameters caused by differences in transmission path length, further improving system measurement consistency. In other words, this scheme achieves multi-electrode gating with a clearer structural relationship, lower wiring complexity, and more consistent electrical characteristics. Therefore, compared to traditional loosely connected multi-channel schemes, this scheme is highly integrated, can be smaller in size, and results in a more portable bioelectrical impedance imaging system.

[0034] In one embodiment, combined with the appendix Figures 4-5 , Figure 4 This is an architecture diagram of the signal conditioning and acquisition device. Figure 5 This is a diagram of the internal structure of the AD5940 analog front-end. The signal conditioning and acquisition device includes the AD594 analog front-end and the signal conditioning circuit connected to it; the AD5940 analog front-end outputs an AC voltage signal, which is connected to the electrode interface device via the signal conditioning circuit. This is used to convert the AC voltage signal into an AC excitation signal, which is then injected into the object under test through the electrode interface device.

[0035] In this embodiment, by employing the AD5940 (a high-precision, low-power analog front-end product from Analog Devices (ADI), which integrates the functions traditionally performed separately by waveform generators, DACs (digital-to-analog converters), analog sampling circuits, ADCs (analog-to-digital converters), and some digital frequency domain processing modules into a single chip, the number of discrete components in the system is reduced, signal links are shortened, system integration is improved, and the product of this system is more suitable for portability and low power consumption.

[0036] Furthermore, the AD5940's internal waveform generation unit generates an AC excitation signal, which is then converted into an AC analog voltage signal by the on-chip DAC and output. Simultaneously, the response signal from the object under test is conditioned and input into the AD5940, where its internal sampling and frequency domain operation module processes it to obtain the amplitude and phase information at the target frequency. In other words, the AD5940 in this solution serves as both the excitation source and the acquisition and feature extraction mechanism, thus forming an integrated measurement structure with the front end as its core.

[0037] In addition, a signal conditioning circuit is located between the AD5940 excitation output terminal and the electrode interface system to convert the AC voltage signal output by the AD5940 into a stable AC excitation signal suitable for bioelectrical impedance measurement, and inject it into the test object through the electrode interface system.

[0038] Specifically, the signal conditioning circuit includes a DC blocking unit, a current limiting unit, a Howland current source unit, and a low-pass filter unit connected in sequence. First, the AC voltage signal output by the AD5940 is blocked by the DC blocking unit to remove the DC component, thereby reducing electrode polarization effects and DC bias influence. Then, the current limiting unit constrains the amplitude of the injected current to meet the safety current requirements of bioelectric measurement scenarios. After that, the signal enters the enhanced Howland current source circuit, which converts the AC voltage signal into a constant AC excitation signal. Then, the low-pass filter unit suppresses high-frequency noise and transient spike interference introduced by switching, so that the injected signal maintains good sinusoidal characteristics. Finally, the signal is selected by the electrode interface system to the target excitation electrode pair, injecting the AC excitation signal into the object under test.

[0039] Therefore, this solution connects the AD5940 chip output to the electrode and uses a closed-loop link consisting of a DC blocking unit, a current limiting unit, a Howland current source unit, and a low-pass filter unit to perform step-by-step engineered processing of the excitation signal, thereby improving the stability and safety of the injected signal. If the excitation source does not possess constant AC characteristics, or if the excitation contains significant DC offset, high-frequency spikes, and amplitude instability, the reliability of the boundary response data will be directly reduced, thus affecting the imaging quality. Therefore, this engineered closed-loop link design ensures the reliability of the injected signal.

[0040] In one embodiment, a response acquisition and conditioning circuit is disposed between the electrode interface system and the AD5940 acquisition input terminal to condition the boundary response signal returned by the object under test so that it meets the requirements of subsequent sampling and feature extraction.

[0041] Specifically, the response acquisition and conditioning circuit includes a DC blocking unit, a high-pass filter unit, and a gain conditioning unit. The boundary response signal output from the measurement electrode pair is passed through the DC blocking unit to remove the DC bias component; subsequently, the high-pass filter unit filters out low-frequency drift, electrode contact polarization voltage, and slowly varying environmental interference; the gain conditioning unit conditions the signal amplitude to match the sampling input range of the AD5940; the conditioned signal is then input to the AD5940, which performs analog-to-digital conversion and frequency domain feature extraction to obtain amplitude and phase information at the target frequency.

[0042] This scheme suppresses high-frequency noise and switching transients on the excitation side, and emphasizes the suppression of low-frequency drift and polarization interference on the response side, thus forming a novel equivalent measurement structure. This structure can maintain signal stability at the excitation end and highlight the effective impedance response near the target frequency band at the acquisition end, thereby achieving selective enhancement of impedance information in the target frequency band and improving the measurement stability and accuracy of the entire bioelectrical impedance imaging system.

[0043] In one embodiment, combined with the appendix Figure 6 , Figure 6 This is an architecture diagram of the control and communication device. The control and communication device includes a main controller and a communication module; the main controller is connected to the multiplexing module and the AD5940 analog front end, respectively, and is used to control the electrode switching sequence, set sampling parameters, manage the stabilization waiting time, and trigger sampling.

[0044] Specifically, the main controller (MCU, such as the STMicroelectronics STM32F4 32-bit ARM MCU in this solution) outputs control signals to the multiplexing module according to the preset excitation and measurement combination rules, so that different electrodes are connected to the excitation path or measurement path in sequence. At the same time, the main controller configures the operating parameters of the AD5940 and triggers its sampling after the electrode switching stabilizes to ensure that the boundary electrical measurement data matches the current electrode connection state.

[0045] Furthermore, the main controller executes a phased switching sequential control strategy, such as disconnection, delay, and connection. Specifically, during each electrode switch, the currently conducting electrode path is first disconnected; then a stable waiting time is set to allow the current field distribution and measurement signal to reach a steady state; then a new excitation electrode pair and / or measurement electrode pair is connected, and the AD5940 sampling is triggered after the waiting time ends.

[0046] Compared to traditional analog switching processes, conventional methods are prone to transient interference and charge injection effects. If sampling occurs immediately after switching, transient errors can easily be introduced into the boundary electrical data. However, the timing control strategy of this scheme, by introducing a waiting time coordinated with the sampling window, can significantly reduce such errors and improve measurement repeatability and system stability.

[0047] Additionally, the communication module is connected to the main controller and is used to send boundary electrical measurement data to an external terminal. In other embodiments, the communication module includes a wired communication unit and a wireless communication unit. The wired communication unit connects to the main controller via a USB-to-serial port to achieve stable wired data interaction with a PC; the wireless communication unit connects to the main controller via a Bluetooth serial port module to achieve wireless transmission with a host computer or mobile terminal, eliminating the limitations of wired communication and effectively improving the overall portability of the device.

[0048] The control and communication device in this solution is designed as the "timing scheduling and data organization hub" of the entire system. On the one hand, it controls electrode switching and front-end sampling to ensure that the measurement link operates under the correct timing; on the other hand, it organizes the measurement results and outputs them to external terminals, thereby ensuring the coordination and consistency of the "gating-sampling-transmission" process at the system level.

[0049] In one embodiment, combined with the appendix Figure 7 , Figure 7 This is a diagram of the power supply unit's architecture. The power supply unit provides operating power to various devices. Specifically, it includes a dual-input power supply unit, an isolated power supply unit, a linear voltage regulator unit, and a bipolar power supply unit. Among them: The dual-input power supply unit connects to both a USB power interface and an external power interface, allowing power from different sources to be fed into the system power bus. In portable scenarios, it can be powered by an external Type-C battery or power bank. In other environments (such as experimental environments), it can also connect to and power a host computer via USB or other interfaces. This dual-input design adapts to different working environments, such as the direct connection requirements in experimental environments, while also supporting independent power supply operation, thus ensuring flexibility in different scenarios.

[0050] The isolated power supply unit connects the system power bus to the signal conditioning and acquisition device, providing electrical isolation between the internal circuitry and the external power supply. The isolated power supply is converted to a stable low-voltage output by a linear regulator and further divided into analog and digital power supplies to reduce the impact of digital switch noise on the analog acquisition link. Furthermore, the bipolar power supply unit connects to the multiplexing module to provide positive and negative power to modules such as analog switches. The use of bipolar power supply improves the conduction performance and switching speed of the analog switches, thereby enhancing signal integrity and switching stability during multi-electrode switching.

[0051] The stability of the system product is directly related to the power supply structure, in addition to the influence of the sampling chip and analog link itself. If the ground loop interference in the power supply path is strong, or if the digital and analog parts share a noisy power supply, the high-precision measurement capability of the front end will be difficult to fully utilize. Therefore, the novel structure of the power supply device in this solution, consisting of a dual-input power supply unit, an isolated power supply unit, a linear voltage regulator unit, and a bipolar power supply unit, enables the power supply device to provide stable support for the entire system, which is also an important foundation for realizing portable high-reliability imaging.

[0052] In one embodiment, the solution is combined with Figure 8 , Figure 8 This is a flowchart of a portable bioelectrical impedance imaging method based on the AD5940. Specifically, the portable bioelectrical impedance imaging method based on the AD5940 includes: Step 1: Switch the connection relationship of multiple electrodes through the electrode interface device, so that one set of electrodes forms an excitation electrode pair and the other set of electrodes forms a measurement electrode pair; Step 2: The excitation signal is output by the signal conditioning and acquisition device and injected into the object under test through the electrode interface device; Step 3: Obtain the boundary response signal of the object under test through the measuring electrode pair. The signal conditioning and acquisition device samples the boundary response signal and extracts its frequency domain features to obtain the boundary electrical measurement data at the target frequency. Step 4: Switch the electrode connection relationship sequentially according to the preset combination of excitation and measurement, and repeat the excitation and measurement process to obtain boundary electrical measurement data corresponding to multiple combinations of excitation and measurement; Step 5: Preprocess the boundary electrical measurement data, input the preprocessed boundary electrical measurement data into the imaging processing module, and obtain the conductivity distribution image of the target area.

[0053] The specific steps of this imaging method are as follows: First, one set of electrodes from multiple electrodes forms an excitation electrode pair, and another set forms a measurement electrode pair. Second, the signal conditioning and acquisition device outputs an excitation signal, which is injected into the object under test through the electrode interface device. The boundary response signal is sampled and frequency domain features are extracted to obtain boundary electrical measurement data at the target frequency. This excitation and measurement process is repeated to obtain boundary electrical measurement data corresponding to multiple combinations of excitation and measurement. Then, the boundary electrical measurement data is denoised, normalized, and outlier processed to form input data suitable for reconstruction. Finally, the processed boundary electrical measurement data is input into the imaging processing module to obtain the conductivity distribution image of the target area.

[0054] In a preferred embodiment, step 5 includes: Step 51: Input the preprocessed boundary electrical measurement data, electrode distribution information, excitation and measurement mode information, and finite element model parameters into the imaging processing module, and obtain the initial conductivity distribution image by solving the physical model; Step 52: Input the initial conductivity distribution image into the deep network for residual correction, and fuse the residual correction result with the initial conductivity distribution image to output the conductivity distribution image of the target region.

[0055] Specifically, the preprocessed boundary electrical measurement data, along with electrode distribution information, excitation and measurement mode information, and finite element model parameters, are input into the imaging processing module. An initial conductivity distribution image is obtained based on the physical model. The physical model solution uses a finite element model to establish the mapping relationship between the boundary voltage and the internal conductivity distribution, and employs the Wexler gradient direction over-relaxation algorithm for iterative solving to obtain an initial conductivity distribution image that satisfies physical constraints. This method strategy allows for obtaining physically consistent initial values, thus providing a reliable foundation for subsequent depth correction.

[0056] In the depth correction stage, the deep network can use U-Net or R2U-Net networks, which are used to learn the residual between the initial conductivity distribution image and the true conductivity distribution, and output the residual correction result. This result is then superimposed and fused with the initial image to improve boundary sharpness and suppress artifacts.

[0057] By adopting the method of "physical model initial value and deep network residual correction", the initial image has already retained the overall structural information and target location information determined by the physical model. The deep network only needs to make targeted corrections to local details, boundary blurring and artifacts that are difficult for the physical model to express accurately. Therefore, it can improve the imaging quality while maintaining physical consistency and enhance the stability and generalization ability of the method.

[0058] Based on this, the portable bioelectrical impedance imaging method based on AD5940, through the collaborative design of highly stable acquisition at the front end and joint reconstruction at the back end, enables the system to not only obtain reliable data, but also to further output conductivity distribution images with good boundary clarity and low artifacts, thus forming a complete imaging closed loop.

[0059] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, terminal device, or network device, etc.) to execute the methods according to the embodiments of this application.

[0060] In an exemplary embodiment of this application, a computer program medium is also provided, on which computer-readable instructions are stored, which, when executed by a computer's processor, cause the computer to perform the methods described in the above method embodiments.

[0061] According to one embodiment of this application, a program product for implementing the methods in the above-described method embodiments is also provided. This product may employ a portable compact disc read-only memory (CD-ROM) and include program code, and may run on a terminal device, such as a personal computer. However, the program product of this invention is not limited thereto. In this document, a readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, apparatus, or device.

[0062] The program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0063] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0064] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0065] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0066] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0067] Furthermore, although the steps of the method in this application are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0068] Through the above description of the embodiments, those skilled in the art will readily understand that the exemplary embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as a CD-ROM, USB flash drive, external hard drive, etc.) or on a network, including several instructions to cause a computing device (such as a personal computer, server, mobile terminal, or network device, etc.) to execute the methods according to the embodiments of this application.

[0069] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the appended claims.

Claims

1. A portable bioelectrical impedance imaging system based on AD5940, characterized in that, It includes an electrode interface device, a signal conditioning and acquisition device, a control and communication device, and a power supply device, wherein: The electrode interface device is connected to the object being measured and is used to connect multiple measuring electrodes. The signal conditioning and acquisition device is electrically connected to the electrode interface device; it is used to output an AC voltage signal and convert it into a stable AC excitation signal through the signal conditioning circuit and then send it to the electrode interface device, and receive the electrical response signal returned by the electrode interface device to obtain the boundary electrical measurement data of the object under test. The control and communication device is connected to the electrode interface device and the signal conditioning and acquisition device respectively; it is used to control electrode switching and acquisition timing, and output the boundary electrical measurement data. The power supply device is electrically connected to the electrode interface device, the signal conditioning and acquisition device and the control and communication device respectively, and is used to provide working power to each device; The AC voltage signal is converted into a stable AC excitation signal by the signal conditioning and acquisition device and then transmitted to the electrode interface device and injected into the object under test. The obtained electrical response signal is returned by the electrode interface device to the signal conditioning and acquisition device for sampling and processing. The control and communication device controls the electrode switching and data acquisition and sends the boundary electrical measurement data to an external terminal for use in electrical impedance imaging.

2. The system according to claim 1, characterized in that, The electrode interface device includes an electrode array and a multi-channel selection module; The electrode array includes multiple electrodes arranged on the boundary of the object under test; one end of the multiple selection module is connected to the multiple electrodes, and the other end is connected to the signal conditioning and acquisition device; The control and communication device is connected to the multiplexing module and is used to control some of the electrodes to form an excitation path, another part of the electrodes to form a measurement path, and the remaining electrodes to be in an open or high-resistance state.

3. The system according to claim 2, characterized in that, The multi-channel selection module consists of multiple analog switches arranged in a parallel mapping structure. The same electrode is connected to the excitation path and the measurement path respectively, and the excitation switching and measurement switching are achieved through the same set of electrode leads. This effectively simplifies wiring, reduces hardware complexity, and minimizes differences between channels.

4. The system according to claim 2, characterized in that, The signal conditioning and acquisition device includes an AD594 analog front-end and a signal conditioning circuit connected thereto. The AD5940 analog front end outputs an AC voltage signal. The signal conditioning circuit is connected to the electrode interface device and is used to convert the AC voltage signal into an AC excitation signal through the signal conditioning circuit. The AC excitation signal is injected into the object under test through the electrode interface device.

5. The system according to claim 4, characterized in that, The signal conditioning circuit includes a DC blocking unit, a current limiting unit, a Howland current source unit, and a low-pass filter unit connected in sequence. The DC blocking unit is used to remove the DC component, the current limiting unit is used to limit the injected current, the Howland current source unit is used to convert the AC voltage signal into a constant AC excitation signal, and the low-pass filter unit is used to suppress high-frequency noise and switching transient interference.

6. The system according to claim 4 or 5, characterized in that, The signal conditioning and acquisition device also includes a response acquisition and conditioning circuit connected to the electrode interface device and the AD5940 analog front end; The response acquisition and conditioning circuit is used to receive the boundary response signal output by the electrode interface device and input the conditioned response signal into the AD5940 analog front end; the AD5940 analog front end performs analog-to-digital conversion and frequency domain feature extraction on the response signal to obtain amplitude and phase information at the target frequency.

7. The system according to claim 6, characterized in that... The response acquisition and conditioning circuit includes a DC blocking unit, a high-pass filter unit, and a gain conditioning unit connected in sequence. The DC blocking unit is used to remove DC bias, the high-pass filter unit is used to suppress low-frequency drift and polarization interference, and the gain conditioning unit is used to adjust the amplitude of the response signal before inputting it into the AD5940 analog front end.

8. The system according to claim 4, characterized in that, The control and communication device includes a main controller and a communication module; The main controller is connected to the multiplexing module and the AD5940 analog front end, respectively, and is used to control the electrode switching sequence, set sampling parameters, manage the stabilization waiting time and trigger sampling. The communication module is connected to the main controller and is used to send the boundary electrical measurement data to an external terminal.

9. A portable bioelectrical impedance imaging method based on AD5940, characterized in that, include: The connection relationship of multiple electrodes is switched by an electrode interface device, so that one set of electrodes forms an excitation electrode pair and another set of electrodes forms a measurement electrode pair. The excitation signal is output by the signal conditioning and acquisition device and injected into the object under test through the electrode interface device; The boundary response signal of the object under test is acquired through the measuring electrodes. The signal conditioning and acquisition device samples the boundary response signal and extracts its frequency domain features to obtain boundary electrical measurement data at the target frequency. The electrode connection relationship is switched sequentially according to the preset combination of excitation and measurement, and the excitation and measurement process is repeated to obtain boundary electrical measurement data corresponding to multiple combinations of excitation and measurement. The boundary electrical measurement data is preprocessed, and the preprocessed boundary electrical measurement data is input into the imaging processing module to obtain the conductivity distribution image of the target area.

10. The system according to claim 9, characterized in that, The step of inputting the preprocessed boundary electrical measurement data into the imaging processing module to obtain an image of the conductivity distribution of the target region includes: The preprocessed boundary electrical measurement data, along with electrode distribution information, excitation and measurement mode information, and finite element model parameters, are input into the imaging processing module, and the initial conductivity distribution image is obtained by solving the physical model. The initial conductivity distribution image is then input into a deep network for residual correction, and the residual correction result is fused with the initial conductivity distribution image to output the conductivity distribution image of the target region.

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