An eight-channel electrochemical impedance spectroscopy compression acquisition and embedded reconstruction system and method

Abstract

The application discloses an eight-channel electrochemical impedance spectrum compression acquisition and embedded reconstruction system and method, and belongs to the fields of electrochemical detection, impedance spectrum measurement, embedded instruments, multi-channel sensing and data reconstruction. The system comprises a master control unit, a plurality of electrochemical impedance acquisition front ends, an electrode interface unit, a communication interface unit, a channel control unit, a storage unit, a spectrum reconstruction unit, a mode configuration unit, a communication output unit and a power management unit. The master control unit controls each electrochemical impedance acquisition front end to acquire complex impedance data of each channel according to a sparse frequency table, and executes a spectrum reconstruction algorithm at an embedded end to reconstruct impedance data at sparse frequency points into electrochemical impedance spectra at a complete frequency table. The application can reduce the number of frequency points of multi-channel electrochemical impedance spectrum acquisition, reduce acquisition time and data transmission volume, and improve the real-time performance, embedded applicability and functional expansion capability of a portable multi-channel electrochemical detection system.

Description

Technical Field

[0001] This invention relates to the fields of electrochemical detection, impedance spectroscopy measurement, embedded instruments, multi-channel sensing and data reconstruction, and in particular to an eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system and method. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) is a commonly used electrochemical detection method. This method involves applying small-amplitude AC excitations to an electrochemical system at different frequencies and acquiring the current or voltage response to obtain the complex impedance information of the measured system at different frequency points. EIS can reflect electrolyte resistance, electrode interfaces, charge transfer, double-layer capacitance, diffusion processes, and sensor interface states, and is therefore widely used in electrochemical sensing, materials analysis, biological detection, corrosion monitoring, and portable detection devices.

[0003] Current electrochemical impedance spectroscopy (EIS) detection typically requires point-by-point scanning across a complete frequency table. For example, to obtain complete Nyquist and Bode curves, a large number of frequency points need to be acquired across high, mid, and low frequency ranges. When the detection system is single-channel, the time and data volume of a complete frequency scan are still acceptable; however, when the system is expanded to eight or more channels, performing a complete frequency scan on each channel leads to a significant increase in acquisition time, data volume, and storage and communication burden on the main control unit, which is detrimental to the realization of portable, multi-channel, and real-time electrochemical impedance spectroscopy detection systems.

[0004] Existing multi-channel electrochemical detection systems typically focus on increasing the number of channels or improving the measurement accuracy of a single channel. However, they lack effective solutions to problems such as long scan times, high frequency redundancy, heavy embedded processing burden, and strong dependence on host computers in multi-channel electrochemical impedance spectroscopy measurements. Although some systems can achieve multi-channel impedance data acquisition, they still require uploading the raw data to a host computer for offline analysis and cannot directly output impedance spectrum results with a complete frequency table on the embedded device.

[0005] Furthermore, simply reducing the number of frequency points results in a loss of impedance spectrum information, affecting the integrity of the Nyquist curve, Bode amplitude curve, and phase curve. Although ordinary interpolation methods can recover the curve shape from a small number of frequency points, they are insufficient to compensate for systematic deviations caused by hardware system errors, channel differences, and changes in the electrochemical system.

[0006] On the other hand, in practical electrochemical sensor testing, in addition to electrochemical impedance spectroscopy (EIS), methods such as cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry, and open-circuit potential are also commonly used for electrode activation, sensor state assessment, system pretreatment, target concentration detection, and auxiliary characterization. If a multi-channel electrochemical impedance spectroscopy system can only execute a single EIS mode, it is difficult to meet the multi-mode detection requirements of a complete sensor testing process. Therefore, there is an urgent need for a portable multi-channel electrochemical detection system that uses multi-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction as its core, while also being compatible with other electrochemical acquisition methods. Summary of the Invention

[0007] Objective of this invention: The objective of this invention is to provide an eight-channel electrochemical impedance spectroscopy (EIS) compressed acquisition and embedded reconstruction system and method to address the problems of long complete frequency scan time, large data volume, low acquisition efficiency after channel expansion, strong dependence on host computer, and incomplete impedance spectrum information after sparse sampling in existing multi-channel EIS detection. Simultaneously, this invention, through a mode configuration unit, is compatible with other electrochemical acquisition methods, enabling the system to be used for electrode activation before and after impedance detection, sensor status checks, auxiliary characterization, and multimodal electrochemical analysis.

[0008] Technical solution: An eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system, comprising: The main control unit is used to generate control commands for electrochemical impedance spectroscopy measurement, configure impedance acquisition parameters, schedule multiple electrochemical impedance acquisition channels, read complex impedance data, and perform embedded spectrum reconstruction. Multiple electrochemical impedance acquisition front-ends, each corresponding to multiple electrochemical detection channels, are used to complete electrochemical impedance measurements at different excitation frequencies and output complex impedance data at the corresponding frequency points. Electrode interface unit, used to connect the working electrode, reference electrode, counter electrode and / or sensing electrode of each electrochemical detection channel; A communication interface unit is used to realize data communication between the main control unit and the multiple electrochemical impedance acquisition front-ends; The channel control unit is used to provide chip select signals, interrupt detection signals, and reset control signals to each electrochemical impedance acquisition front end; The storage unit is used to store the complete frequency table, sparse frequency table, channel calibration parameters, spectrum reconstruction parameters, and electrochemical acquisition mode parameters. The spectrum reconstruction unit is used to reconstruct the electrochemical impedance spectrum of the complete frequency table based on the complex impedance data at sparse frequency points. A mode configuration unit is used to configure the electrochemical impedance spectroscopy acquisition mode and at least one auxiliary electrochemical acquisition mode. a communication output unit, configured to output measurement data at sparse frequency points, the reconstructed impedance spectrum under the complete frequency table and / or auxiliary electrochemical acquisition data to an external device; wherein the main control unit controls each electrochemical impedance acquisition front end to acquire complex impedance data of the corresponding channel according to the sparse frequency table, and reconstructs the complex impedance data into the electrochemical impedance spectrum under the complete frequency table based on an embedded spectrum reconstruction algorithm.

[0009] Further, the number of the plurality of electrochemical impedance acquisition front ends is at least eight, and each electrochemical impedance acquisition front end corresponds to one electrochemical detection channel; alternatively, the system is formed by cascading a plurality of eight-channel acquisition modules to form an electrochemical detection system with sixteen channels, thirty-two channels or more channels; The electrochemical impedance acquisition front end includes one or more of an AC excitation generation module, a response signal acquisition module, an analog-to-digital conversion module, an impedance calculation module, and a digital communication interface module, and is configured to complete electrochemical impedance spectrum measurement and output complex impedance data; in one embodiment, the electrochemical impedance acquisition front end is an AD5941 analog front-end chip, or an equivalent electrochemical analog front-end chip capable of completing AC excitation generation, response acquisition, impedance calculation and digital communication; Each electrochemical impedance acquisition front end is respectively provided with an independent chip select signal, an interrupt signal and a reset signal, the main control unit selects a target acquisition front end according to the chip select signal, reads the impedance measurement result of the corresponding channel according to the interrupt signal, and performs independent reset on the corresponding channel according to the reset signal; The communication interface unit includes a plurality of digital communication interfaces, and the digital communication interfaces are configured to implement parameter configuration and data reading between the main control unit and the electrochemical impedance acquisition front ends; in one embodiment, the digital communication interfaces include a plurality of SPI communication buses, each SPI communication bus is connected to one or more electrochemical impedance acquisition front ends, and different electrochemical impedance acquisition front ends on the same SPI communication bus are selected through independent chip select signals; The communication output unit includes USB, UART, Bluetooth, WiFi or a combination thereof, and is configured to output sparse impedance data, reconstructed impedance data, impedance amplitude, phase, Nyquist curve data, Bode curve data and auxiliary electrochemical acquisition data of each channel.

[0010] Further, the sparse frequency table includes a plurality of frequency points distributed in a high frequency band, a middle frequency band and a low frequency band, and the number of frequency points of the complete frequency table is greater than the number of frequency points of the sparse frequency table; the sparse frequency table includes M frequency points, and the complete frequency table includes N frequency points, where M<N; in one embodiment, M=18 and N=68.

[0011] Furthermore, the complex impedance data includes a real part and an imaginary part of the complex impedance. The spectrum reconstruction unit reconstructs the real part and the imaginary part of the complex impedance, respectively, and further calculates the impedance amplitude and phase. The spectrum reconstruction unit includes a conformal interpolation module and a residual correction module. The conformal interpolation module is used to generate an initial impedance spectrum under a complete frequency table based on the complex impedance data at sparse frequency points. The residual correction module is used to compensate for systematic errors in the initial impedance spectrum. The conformal interpolation module performs piecewise cubic Hermite conformal interpolation on the real part and the imaginary part of the complex impedance under logarithmic frequency coordinates to obtain the initial complex impedance spectrum under a complete frequency table. The residual correction module compensates for the systematic deviation between the initial impedance spectrum and the measured impedance spectrum of the complete frequency table based on a regularized linear residual model, a ridge regression residual model, or an equivalent residual correction model.

[0012] Furthermore, the storage unit is also used to store the calibration parameters of each channel, and the main control unit corrects the gain error, bias error, phase error or residual compensation parameters of different channels according to the calibration parameters; the mode configuration unit is configured to support one or more auxiliary electrochemical acquisition modes among cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry and open circuit potential. When the system is in the electrochemical impedance spectroscopy compression acquisition mode, the main control unit acquires complex impedance data according to the sparse frequency table and performs embedded spectrum reconstruction; when the system is in the auxiliary electrochemical acquisition mode, the main control unit acquires current, voltage or potential data according to the potential waveform, sampling rate, bias potential, scan range, pulse parameters or sampling timing of the corresponding mode. The auxiliary electrochemical acquisition mode is used for electrode activation, sensor status inspection, electrochemical system pretreatment, auxiliary characterization before and after impedance detection, target concentration detection, or multimodal electrochemical analysis.

[0013] This invention also provides an eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction method, applied to the above-mentioned system, including: (1) Establish a complete frequency table and a sparse frequency table, wherein the number of frequency points in the sparse frequency table is less than the number of frequency points in the complete frequency table; (2) Initialize the main control unit, communication interface unit and multiple electrochemical impedance acquisition front-ends; (3) The main control unit selects the current electrochemical detection channel and sets the electrochemical impedance measurement frequency in sequence according to the sparse frequency table; (4) Obtain the complex impedance data of the current channel at sparse frequency points; (5) Determine whether the sparse frequency points of the current channel have been collected. If not, continue to collect the next sparse frequency point; if completed, switch to the next channel. (6) Determine whether multiple channels have completed sparse frequency point acquisition. If not, continue scheduling the channels that have not completed the acquisition. If they have completed the acquisition, proceed to embedded spectrum reconstruction. (7) Perform frequency alignment, outlier detection and data preprocessing on the complex impedance data at sparse frequency points of each channel; (8) Based on the conformal interpolation method, generate the initial impedance spectrum under the complete frequency table based on the complex impedance data at sparse frequency points; (9) The initial impedance spectrum is compensated based on the residual correction model to obtain the reconstructed impedance spectrum under the complete frequency table; (10) Output the reconstructed complex impedance spectrum, impedance amplitude, phase, Nyquist curve data and Bode curve data of each channel.

[0014] Furthermore, in step (8), the conformal interpolation method interpolates the real part and the imaginary part of the complex impedance in the logarithmic frequency coordinates, respectively. In step (9), the residual correction model outputs the residual of the real part and the residual of the imaginary part of the complex impedance in the complete frequency table, and the residual is superimposed on the initial impedance spectrum to obtain the reconstructed impedance spectrum.

[0015] Furthermore, the method also includes an auxiliary electrochemical acquisition step: the main control unit switches between the electrochemical impedance spectroscopy compression acquisition mode and the cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry, or open circuit potential acquisition mode according to external instructions or preset detection procedures. In the auxiliary electrochemical acquisition mode, the main control unit acquires one or more configuration parameters from the electrochemical impedance acquisition front end, including the generated potential waveform, sampling rate, bias potential, scanning potential range, pulse amplitude, pulse width, or sampling timing, and acquires the corresponding current, voltage, or potential data.

[0016] The present invention also provides an electronic device, including a processor and a memory, wherein the memory stores a program that, when executed by the processor, implements the above-described method.

[0017] The present invention also provides a non-volatile computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the above-described method.

[0018] Beneficial effects: 1. This invention uses a sparse frequency table to perform electrochemical impedance spectroscopy measurements, collecting only some key frequency points from the complete frequency table, which can significantly reduce the number of frequency scan points and acquisition time of multi-channel EIS.

[0019] 2. This invention deploys the spectrum reconstruction algorithm in the main control unit, which can reconstruct the impedance spectrum of the complete frequency table from the sparse frequency point complex impedance data on the embedded end, reducing the dependence on offline calculation by the host computer.

[0020] 3. The present invention adopts a spectrum reconstruction method that combines conformal interpolation and residual correction, which can maintain the basic shape of the impedance spectrum curve and compensate for systematic deviations caused by differences in the acquisition front end, channels and electrochemical system.

[0021] 4. This invention uses multiple electrochemical impedance acquisition front-ends to form an eight-channel detection system, and achieves channel-level control through independent chip select, interrupt and reset signals, which is beneficial to improving the stability and maintainability of the multi-channel system.

[0022] 5. This invention can output complex impedance, impedance amplitude, phase, Nyquist curve and Bode curve data with complete frequency table, and is suitable for applications such as portable multi-channel electrochemical detection, biosensing, sweat detection and sensor array testing.

[0023] 6. This invention, through its mode configuration unit, is compatible with auxiliary electrochemical acquisition modes such as cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry, and open circuit potential. It can complete sensor preprocessing, status checking, impedance detection, and other electrochemical characterization within the same hardware system, thereby improving the system's functional expandability.

[0024] 7. The system architecture of this invention can serve as a basic acquisition module, and can be cascaded with multiple eight-channel modules to expand to more channels, providing a foundation for subsequent electrochemical impedance detection systems with thirty-two or more channels. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system of the present invention.

[0026] Figure 2 This is a schematic diagram of the connection structure between the main control unit and eight electrochemical impedance acquisition front-ends of the present invention.

[0027] Figure 3 This is a schematic diagram of the measurement link for a single electrochemical impedance detection channel of the present invention.

[0028] Figure 4 This is a schematic diagram illustrating the relationship between the complete frequency table and the sparse frequency table of this invention.

[0029] Figure 5 This is a flowchart of the multi-channel electrochemical impedance spectroscopy compressed acquisition method of the present invention.

[0030] Figure 6 This is a flowchart of the embedded spectrum reconstruction algorithm of the present invention.

[0031] Figure 7This is a schematic diagram of the spectral reconstruction structure combining conformal interpolation and residual correction of the present invention.

[0032] Figure 8 This is a schematic diagram of the embedded local reconstruction and data output process of the present invention.

[0033] In the picture: 1. Main control unit; 2. Electrochemical impedance acquisition front end; 21. First acquisition front end; 22. Second acquisition front end; 23. Third acquisition front end; 24. Fourth acquisition front end; 25. Fifth acquisition front end; 26. Sixth acquisition front end; 27. Seventh acquisition front end; 28. Eighth acquisition front end; 3. Communication interface unit; 31. SPI 32. Communication bus; 33. Chip select control line; 34. Interrupt detection line; 35. Reset control line; 4. Electrode interface unit; 46. First channel electrode interface; 47. Second channel electrode interface; 48. Third channel electrode interface; 49. Fourth channel electrode interface; 40. Fifth channel electrode interface; 41. Sixth channel electrode interface; 42. Seventh channel electrode interface; 43. Eighth channel electrode interface; 5. Storage unit; 51. Complete frequency table; 52. Sparse frequency table; 53. Reconstruction parameters; 54. Channel calibration parameters; 55. Electrochemical acquisition mode parameters; 6. Spectrum reconstruction unit; 61. Conformal interpolation module; 62. Residual correction module; 63. Impedance spectrum output module; 7. Communication output unit; 8. Power management unit; 9. Electrochemical system under test; 10. Mode configuration unit. Detailed Implementation

[0034] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1: Eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system See Figure 1 This invention provides an eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system. The system includes a main control unit 1, an electrochemical impedance acquisition front-end 2, a communication interface unit 3, an electrode interface unit 4, a storage unit 5, a spectrum reconstruction unit 6, a communication output unit 7, a power management unit 8, a test electrochemical system 9, and a mode configuration unit 10.

[0036] The main control unit 1 is used to complete system initialization, impedance measurement parameter configuration, frequency table calling, channel scheduling, data buffering, spectrum reconstruction, mode switching, and result output. The main control unit 1 can be a microcontroller, digital signal processor, field-programmable gate array (FPGA), system-on-a-chip (SoC), or a combination thereof. The main control unit 1 is configured with multiple communication interfaces, multiple general-purpose input / output interfaces, storage resources, and computing resources to complete multi-channel electrochemical impedance acquisition front-end scheduling, complex impedance data buffering, embedded spectrum reconstruction, and data output. In one specific embodiment, the main control unit 1 uses an STM32H7 series microcontroller; further, the main control unit 1 can use an STM32H743 series microcontroller. The above specific models are only for illustrative purposes and do not constitute a limitation on the scope of protection of this invention. Any microcontroller, digital signal processor, FPGA, SoC, or combination thereof capable of completing multi-channel electrochemical impedance acquisition front-end scheduling, complex impedance data buffering, embedded spectrum reconstruction, and data output can be used as the main control unit 1 of this invention.

[0037] The electrochemical impedance acquisition front-end 2 is used to generate AC excitation signals, acquire the response of the system under test, perform analog-to-digital conversion, calculate impedance, or output complex impedance data. The electrochemical impedance acquisition front-end 2 may include one or more of the following: an AC excitation generation module, a response signal acquisition module, an analog-to-digital conversion module, an impedance calculation module, and a digital communication interface module. Each electrochemical impedance acquisition front-end 2 corresponds to an independent electrochemical detection channel. In one specific embodiment, the electrochemical impedance acquisition front-end 2 uses the AD5941 analog front-end chip, which can perform the AC excitation, response acquisition, and impedance calculation required for electrochemical impedance measurement. The chip model mentioned above is only for illustrative purposes and does not constitute a limitation on the scope of protection of this invention. Any integrated or discrete electrochemical analog front-end capable of generating AC excitation, acquiring response signals, calculating impedance, outputting complex impedance data, and digital communication can be used as the electrochemical impedance acquisition front-end 2 of this invention.

[0038] Electrode interface unit 4 is used to connect to the electrochemical system 9 to be tested. Electrode interface unit 4 may include a working electrode, a reference electrode, a counter electrode, and / or a sensing electrode interface, and can be used for three-electrode electrochemical impedance detection, two-electrode impedance detection, or four-wire impedance detection.

[0039] Storage unit 5 stores a complete frequency table 51, a sparse frequency table 52, reconstruction parameters 53, channel calibration parameters 54, and electrochemical acquisition mode parameters 55. The complete frequency table 51 represents the set of complete impedance spectrum frequency points for which the output needs to be reconstructed, while the sparse frequency table 52 represents the set of key frequency points acquired in the actual acquisition. Reconstruction parameters 53 include conformal interpolation parameters, residual correction model parameters, normalization parameters, or combinations thereof. Channel calibration parameters 54 are used to compensate for differences in gain, bias, phase, or system residuals between different channels. Electrochemical acquisition mode parameters 55 store the potential waveforms, sampling rates, bias potentials, scan ranges, pulse amplitudes, pulse widths, and sampling timing parameters corresponding to modes such as cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry, and open-circuit potential.

[0040] The spectrum reconstruction unit 6 is used to reconstruct the complex impedance data at sparse frequency points into a complex impedance spectrum with a complete frequency table. The spectrum reconstruction unit 6 can be implemented by the main control unit 1 executing an embedded program, or it can be implemented by an independent digital processing module.

[0041] The mode configuration unit 10 is used to configure the system's operating mode. When the system is in the electrochemical impedance spectroscopy compression acquisition mode, the main control unit 1 controls each electrochemical impedance acquisition front-end 2 to acquire complex impedance data according to the sparse frequency table 52, and calls the spectrum reconstruction unit 6 to generate the impedance spectrum under the complete frequency table 51. When the system is in the auxiliary electrochemical acquisition mode, the main control unit 1 configures the corresponding potential waveform, sampling sequence, and sampling rate according to the electrochemical acquisition mode parameters 55, and acquires current, voltage, or potential data.

[0042] The communication output unit 7 is used to output measurement results to external devices. The communication output unit 7 may include USB, UART, Bluetooth, WiFi, or a combination thereof. Output data may include sparse frequency point complex impedance data, reconstructed complex impedance data from a complete frequency table, impedance amplitude, phase, Nyquist curve data, Bode curve data, and auxiliary electrochemical acquisition data.

[0043] The power management unit 8 provides power to the main control unit 1, the electrochemical impedance acquisition front-end 2, and the analog measurement link. The power management unit 8 may include a digital power supply, an analog power supply, a low-noise regulated power supply, a reference voltage source, a filter network, and a ground isolation structure to reduce the interference of digital communication on analog impedance measurement.

[0044] Example 2: Connection structure between the main control unit and eight data acquisition front-ends See Figure 2In one embodiment, the system includes at least eight electrochemical impedance spectroscopy (EIS) acquisition front-ends. For ease of explanation, this embodiment uses eight EIS acquisition front-ends as an example, referred to as the first acquisition front-end 21, the second acquisition front-end 22, the third acquisition front-end 23, the fourth acquisition front-end 24, the fifth acquisition front-end 25, the sixth acquisition front-end 26, the seventh acquisition front-end 27, and the eighth acquisition front-end 28. The eight EIS acquisition front-ends can constitute a basic acquisition module, and multiple basic acquisition modules can be further cascaded to form a sixteen-channel, thirty-two-channel, or more-channel electrochemical detection system.

[0045] The main control unit 1 is connected to eight acquisition front-ends via the communication interface unit 3. The communication interface unit 3 includes multiple SPI communication buses 31. Each SPI communication bus 31 can connect to one or more acquisition front-ends. In one implementation, the main control unit 1 sets four SPI communication buses, each SPI communication bus connecting two acquisition front-ends: SPI1 connects to the first acquisition front-end 21 and the second acquisition front-end 22, SPI2 connects to the third acquisition front-end 23 and the fourth acquisition front-end 24, SPI3 connects to the fifth acquisition front-end 25 and the sixth acquisition front-end 26, and SPI4 connects to the seventh acquisition front-end 27 and the eighth acquisition front-end 28.

[0046] Each acquisition front-end is connected to the main control unit 1 via chip select control line 32, interrupt detection line 33, and reset control line 34. The main control unit 1 selects the target acquisition front-end via chip select control line 32, determines whether the acquisition front-end has completed the impedance measurement at the current frequency point via interrupt detection line 33, and independently resets the corresponding acquisition front-end via reset control line 34.

[0047] The above connection method allows multiple acquisition front-ends to share communication bus resources while maintaining independent channel-level control. Even if a channel malfunctions, it can be reset via an independent reset signal without affecting the normal acquisition of other channels.

[0048] Example 3: Single-channel electrochemical impedance spectroscopy link See Figure 3 A single electrochemical impedance spectroscopy (EIS) detection channel includes a main control unit 1, an electrochemical impedance acquisition front end 2, an electrode interface unit 4, and the electrochemical system to be tested 9.

[0049] During the measurement process, the main control unit 1 sends the measurement parameters for the current frequency point to the electrochemical impedance spectroscopy (EIS) acquisition front-end 2 according to the sparse frequency table 52. The EIS acquisition front-end 2 generates an AC excitation signal at this frequency point and applies it to the electrochemical system 9 under test through the electrode interface unit 4. The electrochemical system 9 under test generates a current or voltage response, and the EIS acquisition front-end 2 acquires, conditions, and calculates the response signal to obtain the complex impedance data at this frequency point.

[0050] Complex impedance data can be expressed as: Z(f) = Z_real(f) + jZ_imag(f) Where Z_real(f) represents the real part of the impedance at frequency f, and Z_imag(f) represents the imaginary part of the impedance at frequency f. After reading the complex impedance data, the main control unit 1 buffers it in the data buffer of the corresponding channel.

[0051] For a three-electrode detection system, electrode interface unit 4 may include a working electrode, a reference electrode, and a counter electrode; for a four-wire impedance detection system, electrode interface unit 4 may include an excitation terminal, a detection terminal, and a sensing terminal. These different electrode connection methods do not affect the implementation of the sparse frequency acquisition and embedded spectrum reconstruction method of this invention.

[0052] Example 4: Complete Frequency Tables and Sparse Frequency Tables See Figure 4 This invention establishes a complete frequency table 51 and a sparse frequency table 52. The complete frequency table 51 includes N frequency points, representing the desired complete impedance spectrum frequency set. The sparse frequency table 52 includes M frequency points, representing the actual frequency set used for performing electrochemical impedance measurements, where M... <N。

[0053] The frequency points in sparse frequency table 52 are distributed across the high, mid, and low frequency bands of the full frequency range, serving to preserve the main morphological information of the impedance spectrum in different frequency regions. These frequency points are preferably distributed on a logarithmic frequency coordinate system to accommodate the characteristic that electrochemical impedance spectra typically exhibit a logarithmic distribution along the frequency axis.

[0054] In one specific embodiment, the complete frequency table 51 includes 68 frequency points, and the sparse frequency table 52 includes 18 frequency points. In this case, the actual number of frequency points acquired is 18 / 68 of the complete number of frequency points, approximately 26.47%. Compared to a complete frequency scan, sparse frequency acquisition can reduce the number of frequency points by approximately 73.53%. The aforementioned 18 and 68 frequency points are merely one embodiment, and the present invention does not limit the specific number of sparse and complete frequency points.

[0055] Example 5: Multichannel electrochemical impedance spectroscopy compressed acquisition method See Figure 5 The multi-channel electrochemical impedance spectroscopy compression acquisition method of the present invention includes the following steps: S101, establish a complete frequency table 51 and a sparse frequency table 52. The complete frequency table 51 includes N frequency points, and the sparse frequency table 52 includes M frequency points, where M... <N。

[0056] S102 initializes the main control unit 1, communication interface unit 3, electrochemical impedance acquisition front-end 2, storage unit 5, mode configuration unit 10, and communication output unit 7. Initialization includes SPI communication parameters, channel chip select status, interrupt triggering mode, reset status, impedance measurement parameters, electrochemical mode parameters, and data buffer.

[0057] S103, the main control unit 1 selects the current detection channel CHi and selects the corresponding electrochemical impedance acquisition front-end 2.

[0058] S104, the main control unit 1 sets the impedance measurement parameters of the current frequency point in sequence according to the sparse frequency table 52, so that the corresponding acquisition front end performs electrochemical impedance measurement at the frequency point.

[0059] S105, the main control unit 1 reads the complex impedance data at the current frequency point, the complex impedance data includes the real part of the complex impedance and the imaginary part of the complex impedance.

[0060] S106, determine whether all M sparse frequency points of the current channel have been collected. If not, return to step S104 to continue collecting the next sparse frequency point; if completed, proceed to step S107.

[0061] S107, determine whether sparse frequency point acquisition has been completed for all channels. If not, switch to the next channel and return to step S103; if completed, proceed to step S108.

[0062] S108, the main control unit 1 calls the spectrum reconstruction unit 6 to perform spectrum reconstruction of the complex impedance data at sparse frequency points of each channel under the complete frequency table.

[0063] S109 outputs the reconstructed complex impedance spectrum, impedance amplitude, phase, Nyquist curve data, and Bode curve data for each channel with complete frequency tables.

[0064] The above multi-channel acquisition process can be executed in a sequential polling manner, or it can be grouped or quasi-parallel scheduled according to the communication resources of the main control unit 1, multiple SPI communication buses 31 and the interrupt status of the acquisition front end.

[0065] Example 6: Embedded Spectrum Reconstruction Algorithm S201, Input the complex impedance data Z_CS at sparse frequency points. Z_CS includes the real part Zreal_CS and the imaginary part Zimag_CS of the complex impedance at each sparse frequency point.

[0066] S202, frequency alignment and outlier detection are performed on the input data. Frequency alignment is used to ensure that the sparse frequency points of the input are consistent with the sparse frequency table 52 in the storage unit 5; outlier detection is used to detect missing points, abrupt changes, or out-of-range data.

[0067] S203 separates the complex impedance data into real and imaginary sequences, which are then fed into the subsequent reconstruction process.

[0068] S204 converts the frequency coordinates to logarithmic frequency coordinates. Since electrochemical impedance spectroscopy typically exhibits good smoothness on the logarithmic frequency axis, interpolation in logarithmic frequency coordinates helps maintain the continuity of the spectral shape.

[0069] S205, using the conformal interpolation method, the real and imaginary parts of the complex impedance at sparse frequency points are interpolated to obtain the initial complex impedance spectrum Z_interp under the complete frequency table 51.

[0070] S206 invokes the residual correction model to calculate the residual compensation ΔZ under the complete frequency table based on the complex impedance data at sparse frequency points, the initial complex impedance spectrum, or a combination thereof. The residual compensation includes the real residual ΔZreal and the imaginary residual ΔZimag.

[0071] S207, the residual compensation is superimposed onto the initial complex impedance spectrum to obtain the reconstructed complex impedance spectrum: Z_recon = Z_interp + ΔZ S208, calculate the impedance amplitude and phase based on the reconstructed complex impedance spectrum. The impedance amplitude can be calculated from the real and imaginary parts of the complex impedance, and the phase can be calculated from the arctangent relationship between the imaginary and real parts.

[0072] S209 outputs the complex impedance spectrum, impedance amplitude, phase, Nyquist curve data, and Bode curve data under the complete frequency table 51.

[0073] The spectrum reconstruction algorithm can be deployed in the main control unit 1 through a C language program, or it can be implemented through other embedded programs, firmware modules or digital signal processing units.

[0074] Example 7: Reconstructed Structure Combining Conformal Interpolation and Residual Correction See Figure 7 The spectrum reconstruction unit 6 of the present invention includes a conformal interpolation module 61, a residual correction module 62, and an impedance spectrum output module 63.

[0075] The conformal interpolation module 61 is used to recover the initial impedance spectrum under the complete frequency table based on the complex impedance data at sparse frequency points. Preferably, the conformal interpolation module 61 performs piecewise cubic Hermite conformal interpolation on the real and imaginary parts of the complex impedance in logarithmic frequency coordinates. This method can reduce the overshoot phenomenon that may occur in higher-order interpolation and maintain the continuity and local shape of the impedance spectrum curve.

[0076] The residual correction module 62 is used to compensate for systematic deviations between the conformal interpolation results and the true complete frequency table impedance spectrum. In one embodiment, the residual correction module 62 employs a regularized linear residual model or a ridge regression residual model. This model takes complex impedance data at sparse frequency points, the initial impedance spectrum obtained by conformal interpolation, or a combination thereof as input, and outputs the residual compensation amount for the complete frequency table. The residual compensation amount is added to the initial impedance spectrum to obtain the reconstructed impedance spectrum.

[0077] The impedance spectrum output module 63 is used to generate complex impedance, impedance amplitude, phase, Nyquist curve data and Bode curve data in a complete frequency table based on the reconstructed complex impedance spectrum.

[0078] The reconstruction structure combining conformal interpolation and residual correction described above can balance spectral stability and error compensation capabilities. Conformal interpolation is used to restore the basic impedance spectrum shape between sparse frequency points, while residual correction is used to compensate for systematic deviations caused by changes in the acquisition front end, channel differences, frequency response, and electrochemical system.

[0079] Example 8: Embedded Local Reconfiguration and Data Output See Figure 8 This invention deploys the spectrum reconstruction algorithm in the main control unit 1 to achieve embedded local reconstruction.

[0080] In one implementation, eight electrochemical impedance acquisition front-ends 2 acquire complex impedance data at only M frequency points according to the sparse frequency table 52. The main control unit 1 stores the sparse complex impedance data of each channel in the data buffer and calls the complete frequency table 51, sparse frequency table 52, reconstruction parameters 53, and channel calibration parameters 54 in the storage unit 5. Subsequently, the main control unit 1 sequentially calls the conformal interpolation module 61 and the residual correction module 62 to generate the reconstructed impedance spectrum under the complete frequency table 51.

[0081] After reconstruction, the main control unit 1 can store the impedance spectrum results under the complete frequency table locally, or upload them to a PC, mobile terminal, host computer software, or cloud system via the communication output unit 7. The uploaded content can include the original data of sparse frequency points, the reconstructed data under the complete frequency table, impedance amplitude, phase, Nyquist curve data, Bode curve data, channel number, acquisition time, and calibration status.

[0082] When the system is in auxiliary electrochemical acquisition mode, the main control unit 1 can output cyclic voltammetry curve data, timing ampere current data, differential pulse voltammetry peak data, square wave voltammetry response data, linear scan voltammetry data, or open circuit potential change data through the communication output unit 7.

[0083] By employing the above method, the present invention eliminates the need to upload all original impedance data to a host computer for offline reconstruction, thereby reducing data transmission volume and improving the real-time performance and independent operation capability of portable multi-channel electrochemical detection equipment.

[0084] Example 9: Channel Calibration and Error Compensation Since there may be differences in devices, analog links, interface parasitic parameters and electrode connections among multiple electrochemical impedance acquisition front-ends 2, the present invention further sets channel calibration parameters 54.

[0085] The channel calibration parameter 54 can be obtained through standard impedance, standard RC network, standard electrochemical system, or blank electrolyte testing. The channel calibration parameter 54 may include impedance amplitude calibration coefficient, phase calibration coefficient, complex impedance real part bias, complex impedance imaginary part bias, channel gain correction parameter, or residual model channel parameter.

[0086] During the reconstruction process, the main control unit 1 can first perform channel calibration on the complex impedance data at sparse frequency points, and then perform conformal interpolation and residual correction; alternatively, it can introduce channel calibration parameter 54 during the residual correction stage to give different channels independent residual compensation parameters. In this way, the systematic differences between multiple channels can be reduced, and the consistency and stability of the eight-channel impedance measurement results can be improved.

[0087] In the assisted electrochemical acquisition mode, the channel calibration parameter 54 can also be used to correct the differences in current gain, voltage bias, baseline drift and electrode initial state of different channels, thereby improving the consistency of cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry and open circuit potential acquisition results.

[0088] Example 10: Compatibility with Multiple Electrochemical Acquisition Modes In addition to being used for electrochemical impedance spectroscopy measurement, the electrochemical impedance acquisition front-end 2 of the present invention can also be configured by the main control unit 1 with excitation waveform, sampling rate, bias potential, scan potential range, pulse amplitude, pulse width and measurement timing to realize one or more auxiliary electrochemical acquisition modes among cyclic voltammetry, chronoampere, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry and open circuit potential.

[0089] In one implementation, the main control unit 1 sends configuration parameters for different modes to the electrochemical impedance acquisition front-end 2 via the communication interface unit 3. When the system is in the electrochemical impedance spectroscopy compression acquisition mode, the main control unit 1 acquires complex impedance data according to the sparse frequency table 52 and performs embedded spectrum reconstruction; when the system is in the cyclic voltammetry mode, the main control unit 1 configures the scan start potential, end potential, scan rate, and sampling rate, and acquires the current-potential curve; when the system is in the timed ampere mode, the main control unit 1 configures the constant bias potential and sampling time, and acquires the current-time curve; when the system is in the differential pulse voltammetry or square wave voltammetry mode, the main control unit 1 configures the pulse amplitude, pulse width, step potential, and sampling window, and acquires the corresponding pulse response data; when the system is in the linear scan voltammetry mode, the main control unit 1 configures the linear scan range and scan rate, and acquires the current response; when the system is in the open circuit potential mode, the main control unit 1 acquires data on the change of electrode potential over time without applying external polarization.

[0090] The aforementioned auxiliary electrochemical acquisition modes can be used for electrode activation, sensor status checks, electrochemical system pretreatment, auxiliary characterization before and after impedance detection, target concentration detection, and multimodal electrochemical analysis. This multimodal compatibility function does not change the core technical solution of this invention, which is based on sparse frequency electrochemical impedance acquisition and embedded complete impedance spectrum reconstruction.

[0091] Example 11: System Expansion

[0092] The eight-channel system described in this invention can serve as a basic acquisition module. Multiple eight-channel acquisition modules can be connected to the next-level main control module via UART, SPI, USB, CAN, RS485, or other communication methods, thereby expanding into a sixteen-channel, thirty-two-channel, or more-channel electrochemical detection system.

[0093] In the extended system, each eight-channel acquisition module can independently complete sparse frequency point acquisition and local spectrum reconstruction, while the upper-level main control module is only responsible for module scheduling, data aggregation, time synchronization, and result uploading. This structure can reduce the data processing pressure of centralized main control and is conducive to building high-channel-count, portable, or distributed electrochemical impedance spectroscopy systems.

[0094] Meanwhile, each eight-channel acquisition module can also select to execute either the electrochemical impedance spectroscopy compressed acquisition mode or the auxiliary electrochemical acquisition mode according to application requirements, thereby enabling the extended system to simultaneously possess multi-channel impedance spectroscopy detection capability and multi-mode electrochemical acquisition capability.

[0095] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system, characterized in that, include: The main control unit is used to generate control commands for electrochemical impedance spectroscopy measurement, configure impedance acquisition parameters, schedule multiple electrochemical impedance acquisition channels, read complex impedance data, and perform embedded spectrum reconstruction. Multiple electrochemical impedance acquisition front-ends, each corresponding to multiple electrochemical detection channels, are used to complete electrochemical impedance measurements at different excitation frequencies and output complex impedance data at the corresponding frequency points. Electrode interface unit, used to connect the working electrode, reference electrode, counter electrode and / or sensing electrode of each electrochemical detection channel; A communication interface unit is used to realize data communication between the main control unit and the multiple electrochemical impedance acquisition front-ends; The channel control unit is used to provide chip select signals, interrupt detection signals, and reset control signals to each electrochemical impedance acquisition front end; The storage unit is used to store the complete frequency table, sparse frequency table, channel calibration parameters, spectrum reconstruction parameters, and electrochemical acquisition mode parameters. The spectrum reconstruction unit is used to reconstruct the electrochemical impedance spectrum of the complete frequency table based on the complex impedance data at sparse frequency points. A mode configuration unit is used to configure the electrochemical impedance spectroscopy acquisition mode and at least one auxiliary electrochemical acquisition mode. The communication output unit is used to output measurement data at sparse frequency points, reconstructed impedance spectra at complete frequency tables, and / or auxiliary electrochemical acquisition data to external devices. The main control unit controls each electrochemical impedance acquisition front end to acquire complex impedance data of the corresponding channel according to the sparse frequency table, and reconstructs the complex impedance data into an electrochemical impedance spectrum under the complete frequency table based on the embedded spectrum reconstruction algorithm.

2. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system according to claim 1, characterized in that, The number of the plurality of electrochemical impedance acquisition front-ends is at least eight, and each electrochemical impedance acquisition front-end corresponds to one electrochemical detection channel; or, the system is formed by cascading multiple eight-channel acquisition modules to form a sixteen-channel, thirty-two-channel or more-channel electrochemical detection system. The electrochemical impedance acquisition front end includes one or more of the following: an AC excitation generation module, a response signal acquisition module, an analog-to-digital conversion module, an impedance calculation module, and a digital communication interface module, used to complete electrochemical impedance spectroscopy measurement and output complex impedance data; in one embodiment, the electrochemical impedance acquisition front end is an AD5941 analog front end chip, or an equivalent electrochemical analog front end chip capable of completing AC excitation generation, response acquisition, impedance calculation, and digital communication; Each electrochemical impedance acquisition front end has an independent chip select signal, interrupt signal, and reset signal. The main control unit selects the target acquisition front end according to the chip select signal, reads the impedance measurement results of the corresponding channel according to the interrupt signal, and independently resets the corresponding channel according to the reset signal. The communication interface unit comprises a plurality of digital communication interfaces, where the digital communication interfaces are configured to implement parameter configuration and data reading between the main control unit and the electrochemical impedance acquisition front ends. In one embodiment, the digital communication interfaces comprise a plurality of SPI communication buses, each SPI communication bus is connected to one or more electrochemical impedance acquisition front ends, and different electrochemical impedance acquisition front ends on the same SPI communication bus are selected through independent chip select signals; The communication output unit comprises USB, UART, Bluetooth, WiFi or a combination thereof, and is configured to output sparse impedance data, reconstructed impedance data, impedance amplitude, phase, Nyquist curve data, Bode curve data and auxiliary electrochemical acquisition data of each channel.

3. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system according to claim 1, characterized in that, The sparse frequency table comprises a plurality of frequency points distributed in a high frequency band, a middle frequency band and a low frequency band, and the number of frequency points in the complete frequency table is greater than the number of frequency points in the sparse frequency table; the sparse frequency table comprises M frequency points, the complete frequency table comprises N frequency points, where M<N; in one embodiment, M=18 and N=68.

4. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system according to claim 1, characterized in that, The complex impedance data comprises a real part of complex impedance and an imaginary part of complex impedance, and the spectrum reconstruction unit reconstructs the real part of complex impedance and the imaginary part of complex impedance respectively, and further calculates the impedance amplitude and phase; the spectrum reconstruction unit comprises a shape-preserving interpolation module and a residual correction module, the shape-preserving interpolation module is configured to generate an initial impedance spectrum under the complete frequency table according to the complex impedance data at the sparse frequency points, and the residual correction module is configured to perform systematic error compensation on the initial impedance spectrum; the shape-preserving interpolation module performs piecewise cubic Hermite shape-preserving interpolation on the real part of complex impedance and the imaginary part of complex impedance respectively under the logarithmic frequency coordinate, to obtain an initial complex impedance spectrum under the complete frequency table; the residual correction module compensates for the systematic deviation between the initial impedance spectrum and the measured impedance spectrum of the complete frequency table based on a regularized linear residual model, a ridge regression residual model or an equivalent residual correction model thereof.

5. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction system according to claim 1, characterized in that, The storage unit is further configured to store calibration parameters of each channel, and the main control unit corrects gain errors, offset errors, phase errors or residual compensation parameters of different channels according to the calibration parameters; the mode configuration unit is configured to support one or more auxiliary electrochemical acquisition modes of cyclic voltammetry, chronoamperometry, differential pulse voltammetry, square wave voltammetry, linear sweep voltammetry and open circuit potential; When the system is in the electrochemical impedance spectrum compressed acquisition mode, the main control unit acquires complex impedance data according to the sparse frequency table and executes embedded spectrum reconstruction; When the system is in the auxiliary electrochemical acquisition mode, the main control unit acquires current, voltage or potential data according to the potential waveform, sampling rate, bias potential, scanning range, pulse parameters or sampling timing of the corresponding mode; The auxiliary electrochemical acquisition mode is used for electrode activation, sensor state inspection, electrochemical system pretreatment, auxiliary characterization before and after impedance detection, target concentration detection or multimodal electrochemical analysis.

6. An eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction method, applied to the system described in any one of claims 1 to 5, characterized in that, comprising: (1) Establish a complete frequency table and a sparse frequency table, wherein the number of frequency points in the sparse frequency table is less than the number of frequency points in the complete frequency table; (2) Initialize the main control unit, communication interface unit and multiple electrochemical impedance acquisition front-ends; (3) The main control unit selects the current electrochemical detection channel and sets the electrochemical impedance measurement frequency in sequence according to the sparse frequency table; (4) Obtain the complex impedance data of the current channel at sparse frequency points; (5) Determine whether the sparse frequency points of the current channel have been collected. If not, continue to collect the next sparse frequency point. If completed, switch to the next channel; (6) Determine whether multiple channels have completed sparse frequency point acquisition. If not, continue scheduling the channels that have not completed the acquisition. If completed, proceed to embedded spectrum reconstruction; (7) Perform frequency alignment, outlier detection and data preprocessing on the complex impedance data at sparse frequency points of each channel; (8) Based on the conformal interpolation method, generate the initial impedance spectrum under the complete frequency table based on the complex impedance data at sparse frequency points; (9) The initial impedance spectrum is compensated based on the residual correction model to obtain the reconstructed impedance spectrum under the complete frequency table; (10) Output the reconstructed complex impedance spectrum, impedance amplitude, phase, Nyquist curve data and Bode curve data of each channel.

7. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction method according to claim 6, characterized in that, In step (8), the conformal interpolation method interpolates the real part and the imaginary part of the complex impedance in logarithmic frequency coordinates. In step (9), the residual correction model outputs the real part residual and the imaginary part residual of the complex impedance in the complete frequency table, and the residual is superimposed on the initial impedance spectrum to obtain the reconstructed impedance spectrum.

8. The eight-channel electrochemical impedance spectroscopy compressed acquisition and embedded reconstruction method according to claim 6, characterized in that, The method also includes an auxiliary electrochemical acquisition step: the main control unit switches between the electrochemical impedance spectroscopy compression acquisition mode and the cyclic voltammetry, chronoampere, differential pulse voltammetry, square wave voltammetry, linear scan voltammetry or open circuit potential acquisition mode according to external instructions or preset detection procedures. In the auxiliary electrochemical acquisition mode, the main control unit acquires one or more configuration parameters from the electrochemical impedance acquisition front end, including the generated potential waveform, sampling rate, bias potential, scanning potential range, pulse amplitude, pulse width, or sampling timing, and acquires the corresponding current, voltage, or potential data.

9. An electronic device, characterized in that, It includes a processor and a memory, wherein the memory stores a program that, when executed by the processor, implements the method of any one of claims 6 to 8.

10. A non-volatile computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by a processor, it implements the method described in any one of claims 6 to 8.

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