Multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system and method

Abstract

The application discloses a kind of multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system and method, it is related to extremely weak magnetic signal detection technical field, improves magnetic relaxation signal measurement accuracy. Including: state acquisition unit, joint determination and timing control unit, data acquisition and processing unit;State acquisition unit is used to obtain the multidimensional state information of magnetization region of magnetic nanoparticle after magnetization excitation is cancelled in real time;Joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of magnetic nanoparticle according to multidimensional state information;Data acquisition and processing unit are used to collect the initial magnetic relaxation signal of magnetic nanoparticle based on magnetic relaxation signal acquisition time, determine the reference background noise of noise measurement channel, determine the measurement background noise of signal measurement channel based on reference background noise, separate out interference-free magnetic relaxation signal in initial magnetic relaxation signal based on measurement background noise.The application is suitable for magnetic relaxation signal measurement scene.

Description

Technical Field

[0001] This invention relates to the field of extremely weak magnetic signal detection technology, and in particular to a magnetic nanoparticle magnetic relaxation signal measurement system and method for multi-state joint determination. Background Technology

[0002] Magnetic nanoparticles can generate a magnetization response under the influence of an external magnetic field. After the external magnetic field is removed, the magnetic moments of the particles undergo reorientation or thermal relaxation over time, thus forming a magnetic response that decays over time, i.e., a magnetic relaxation signal. By measuring the magnetic relaxation signal of magnetic nanoparticles, their macroscopic physical properties can be inverted, thereby serving biomedical and industrial detection.

[0003] Currently, the magnetic relaxation signal of magnetic nanoparticles is typically measured after a fixed time has elapsed following the removal of the magnetization excitation. However, the recovery time of magnetic nanoparticles after the removal of the magnetization excitation is variable. If the fixed time is too short, residual signals may be introduced, while if the fixed time is too long, the early high-amplitude signals of the particles may be lost, resulting in low accuracy in measuring the magnetic relaxation signal of magnetic nanoparticles. Summary of the Invention

[0004] This invention provides a multi-state joint determination magnetic relaxation signal measurement system and method for magnetic nanoparticles, which mainly improves the measurement accuracy of magnetic relaxation signals of magnetic nanoparticles.

[0005] According to a first aspect of the present invention, a magnetic nanoparticle magnetic relaxation signal measurement system with multi-state joint determination is provided, comprising: a state acquisition unit, a joint determination and timing control unit, and a data acquisition and processing unit; The state acquisition unit is used to respond to the magnetization excitation cancellation signal of the magnetic nanoparticle under test after applying magnetization excitation, and to acquire multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time. The multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of background magnetic field and working state data of extremely weak magnetic field measurement device. The joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information. The data acquisition and processing unit is used to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determine the reference background noise of the background magnetic field in the noise measurement channel, determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determine the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separate the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise.

[0006] Optionally, the joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information by performing the following steps: Determine whether the multi-dimensional state information meets the magnetic relaxation signal measurement conditions. Specifically, determine whether the rate of change of current in the magnetization excitation circuit after the magnetization excitation is removed is less than or equal to a preset current threshold, whether the rate of change of amplitude of the background residual magnetic field is less than or equal to a preset magnetic field threshold, and whether the extremely weak magnetic field measuring device has entered the allowable measurement state. If the rate of change of current in the magnetization excitation circuit is less than or equal to the preset current threshold, the rate of change of amplitude of the background residual magnetic field is less than or equal to the preset magnetic field threshold, and the extremely weak magnetic field measuring device has entered the allowable measurement state, then the multi-dimensional state information is determined to meet the magnetic relaxation signal measurement conditions. Otherwise, the multi-dimensional state information is determined not to meet the magnetic relaxation signal measurement conditions. When the multi-dimensional state information satisfies the magnetic relaxation signal measurement conditions, the moment when the magnetic relaxation signal measurement conditions are met is determined as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle under test.

[0007] Optionally, the joint determination and timing control unit is used to determine whether the extremely weak magnetic field measuring device has entered the allowable measurement state by performing the following steps: Determine the recovery status evaluation value of the extremely weak magnetic field measuring device: ,in, The recovery state evaluation value of the extremely weak magnetic field measuring device, , and They are respectively weighting coefficients, The measurement information of the extremely weak magnetic field measuring device at the current time t, The measurement deviation between the measurement information of the extremely weak magnetic field measuring device at the current time t and the baseline information. The noise level of the extremely weak magnetic field measuring device at the current time t, , and This corresponds to the normalized scales of measurement bias, rate of change of measurement information, and noise level. If the recovery status evaluation value is less than or equal to the preset recovery status threshold, then the extremely weak magnetic field measuring device is determined to have entered the allowable measurement state; otherwise, the extremely weak magnetic field measuring device is determined not to have entered the allowable measurement state.

[0008] Optionally, it also includes: a residual field processing unit; The residual field processing unit is used to determine whether the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is greater than a preset time threshold when the multi-dimensional state information does not meet the magnetic relaxation signal measurement conditions. If so, it determines a processing action to reduce the influence of the residual magnetic field in the magnetized region based on the magnetization excitation state data of the magnetized region where the magnetic nanoparticle to be measured is located and the background residual magnetic field state data of the background magnetic field. Based on the processing action, it performs magnetic field regulation processing on the magnetized region. The joint determination and timing control unit is also used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information of the magnetized region where the magnetic nanoparticle under test is located after magnetic field modulation processing.

[0009] Optionally, The joint determination and timing control unit is also used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located at the next time corresponding to the current time when the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is less than or equal to the preset time threshold.

[0010] Optionally, the joint determination and timing control unit is used to determine the moment when the magnetic relaxation signal measurement conditions are met as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle under test by performing the following steps: The historical magnetic response amplitude of the magnetic nanoparticle under test at multiple historical sampling points is obtained, and the predicted magnetic response amplitude of the magnetic nanoparticle under test at the moment when the magnetic relaxation signal measurement conditions are met is determined based on the historical magnetic response amplitude. The measurement noise level is determined based on the measurement information from the extremely weak magnetic measuring device prior to the application of magnetization excitation, and the background noise correction error in the magnetized region is determined. The accuracy verification coefficient is determined based on the predicted magnetic response amplitude, the measured noise level, and the background noise correction error. ,in, To verify the accuracy of the coefficients, The timing for satisfying the magnetic relaxation signal measurement conditions The predicted magnetic response amplitude, The timing for satisfying the magnetic relaxation signal measurement conditions Measurement noise level, The timing for satisfying the magnetic relaxation signal measurement conditions Background noise correction error; The accuracy of the time that meets the magnetic relaxation signal measurement conditions is verified based on the accuracy verification coefficient. The time that meets the magnetic relaxation signal measurement conditions and passes the accuracy verification is determined as the magnetic relaxation signal acquisition time of the magnetic nanoparticle to be measured.

[0011] Optionally, the data acquisition and processing unit is configured to determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel by performing the following steps: After applying and removing the magnetizing field in the measurement area which is in a blank area, the measurement channel signal sequence output by the measurement channel for the blank area and the reference channel signal sequence output by the reference channel for the background magnetic field of the measurement area are acquired synchronously. Using the reference channel signal sequence as the independent variable and the measurement channel signal sequence as the dependent variable, a linear error function is constructed. The scaling factor that minimizes the sum of squared residuals of the linear error function is then calculated, and the scaling factor is used as the background noise coupling coefficient between the signal measurement channel and the noise measurement channel.

[0012] Optionally, it also includes a parameter update unit; The parameter update unit is used to determine the abnormal state category of the magnetization region based on the multi-dimensional state information and the initial magnetic relaxation signal. The abnormal state category includes at least one of magnetization excitation state abnormality, background residual magnetic field state abnormality, extremely weak magnetic measurement device abnormality, and magnetic relaxation signal quality abnormality. Based on the abnormal state category, the unit determines the magnetization excitation condition configuration parameters for the next magnetic relaxation signal measurement cycle and updates the magnetization excitation condition of the magnetic nanoparticles to be measured for the next magnetic relaxation signal measurement cycle based on the magnetization excitation condition configuration parameters.

[0013] Optionally, the data acquisition and processing unit is configured to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time by performing the following steps: The magnetic relaxation signal acquisition window is determined based on the magnetic relaxation signal acquisition time. The rough magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel is acquired based on the magnetic relaxation signal acquisition window. The initial magnetic relaxation signal is then selected from the rough magnetic relaxation signal.

[0014] According to a second aspect of the present invention, a method for measuring magnetic relaxation signals of magnetic nanoparticles based on multi-state joint determination is provided. The method is applied to the aforementioned multi-state joint determination magnetic relaxation signal measurement system for magnetic nanoparticles, and the method includes: The state acquisition unit responds to the magnetization excitation cancellation signal of the magnetic nanoparticle under test after the magnetization excitation is applied, and acquires multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time. The multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of background magnetic field and working state data of extremely weak magnetic measurement device. The joint judgment and timing control unit determines the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information; The data acquisition and processing unit acquires the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determines the reference background noise of the background magnetic field in the noise measurement channel, determines the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determines the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separates the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise.

[0015] According to a third aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for measuring magnetic relaxation signals of magnetic nanoparticles through multi-state joint determination.

[0016] According to a fourth aspect of the present invention, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-mentioned method for measuring magnetic relaxation signals of magnetic nanoparticles with multi-state joint determination.

[0017] The present invention provides a multi-state joint determination magnetic relaxation signal measurement system and method for magnetic nanoparticles. Compared with the current method of measuring the magnetic relaxation signal of magnetic nanoparticles after the magnetization excitation of magnetic nanoparticles is removed and a fixed time is waited, the present invention dynamically determines the acquisition time of the magnetic relaxation signal based on multi-dimensional state information. On the one hand, it avoids the problem of early loss of strong signals of magnetic nanoparticles due to excessive fixed waiting time, significantly improving the temporal resolution and signal-to-noise ratio of signal acquisition. On the other hand, it prevents the introduction of strong interference when the system is not fully stable due to insufficient waiting time, ensuring that the acquisition window is always opened at the optimal state of lowest system noise and purest signal, thereby improving the detection sensitivity and accuracy of weak magnetic relaxation signals. By using the background noise coupling coefficient between the signal measurement channel and the noise measurement channel through the data acquisition and processing unit, the reference background noise is converted into accurate measurement background noise and separated. This can accurately remove residual background noise and environmental interference, extracting high-fidelity interference-free magnetic relaxation signals of the magnetic nanoparticles under test from complex initial signals, further improving the measurement accuracy of magnetic relaxation signals. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This diagram illustrates the structure of a multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system provided in an embodiment of the present invention. Figure 2 This diagram illustrates the spatial arrangement of multiple units in a multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system provided by an embodiment of the present invention. Figure 3 A schematic diagram of another multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system provided by an embodiment of the present invention is shown. Detailed Implementation

[0019] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the present application can be combined with each other.

[0020] Currently, the method of measuring the magnetic relaxation signal of magnetic nanoparticles after removing the magnetization excitation and waiting for a fixed time is problematic. The recovery time of magnetic nanoparticles after the magnetization excitation is removed is fluctuating. If the fixed time is too short, residual signals may be mixed in, while if the fixed time is too long, the early high-amplitude signals of the particles may be lost, resulting in low accuracy of the measurement of the magnetic relaxation signal of magnetic nanoparticles.

[0021] To address the aforementioned problems, embodiments of the present invention provide a multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system, such as... Figure 1 As shown, it includes: a status acquisition unit, a joint decision and timing control unit, and a data acquisition and processing unit; The state acquisition unit is used to respond to the magnetization excitation cancellation signal of the magnetic nanoparticle under test after applying magnetization excitation, and to acquire multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time. The multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of background magnetic field and working state data of extremely weak magnetic field measurement device. The joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information. The data acquisition and processing unit is used to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determine the reference background noise of the background magnetic field in the noise measurement channel, determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determine the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separate the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise.

[0022] This invention addresses the limitations of measuring magnetic relaxation signals from magnetic nanoparticles by proposing a multi-state joint determination system for measuring magnetic relaxation signals from magnetic nanoparticles. This system integrates a state acquisition unit, a joint determination and timing control unit, and a data acquisition and processing unit to achieve accurate measurement of magnetic relaxation signals from magnetic nanoparticles. All units are electrically connected. The multi-state joint determination system also includes a magnetization excitation unit. This unit forms a magnetized field in the region where the magnetic nanoparticle is located. The magnetization excitation unit includes a first magnetization coil and a second magnetization coil positioned on opposite sides of the magnetic nanoparticle. The first and second magnetization coils together form a magnetized region at the location of the magnetic nanoparticle to apply magnetization excitation. It should be noted that the magnetization excitation unit is not limited to the two-coil structure described above; it can also employ Helmholtz coils, dual-plane coils, saddle coils, solenoids, planar coils, gradient coils, or other devices capable of applying a magnetized field to the magnetic nanoparticle. The magnetic nanoparticles to be tested can be carried in sample tubes, sample cells, microfluidic cavities, trays, reaction vessels, or other structures that can maintain the spatial position of the magnetic nanoparticles. After the magnetization excitation unit applies magnetization excitation to the magnetic nanoparticles to be tested for a certain period of time and then removes the magnetization excitation, the start-up state acquisition unit uses a sensor or Rogowski coil to sample the voltage across the excitation coil and the transient current waveform flowing through the coil in real time. Due to the inductive characteristics of the excitation coil, the current will not drop to zero instantaneously, but will exhibit an exponential decay or oscillating decay process. Therefore, the transient current value, current change rate, and equivalent current are used as magnetization excitation state data. At the same time, the background residual magnetic field state data such as the single-axis or multi-axis magnetic field amplitude, magnetic field amplitude change rate, magnetic field amplitude stability, or background estimation error of the background magnetic field in the magnetized region are collected, as well as the working state data of the extremely weak magnetic measurement device, such as the sensor's saturation mark, lock-in state, output deviation relative to the baseline, output change rate, short-time noise, or closed-loop compensation amount are collected. The state acquisition unit sends the acquired multi-dimensional state information to the joint judgment and timing control unit. The joint judgment and timing control unit determines the moment when the multi-dimensional state information simultaneously satisfies the requirement to measure the magnetic relaxation signal, and uses this moment as the magnetic relaxation signal acquisition moment. The joint judgment and timing control unit sends the magnetic relaxation signal acquisition moment to the data acquisition and processing unit. Upon receiving the magnetic relaxation signal acquisition moment, the data acquisition and processing unit initiates dual-channel synchronous data acquisition. Under the same time reference, it acquires the signals from the signal measurement channel and the noise measurement channel, respectively. The signal acquired by the signal measurement channel includes the actual magnetic relaxation signal of the magnetic nanoparticle under test, as well as measurement background noise such as environmental background noise and circuit thermal noise superimposed on it, and is called the initial magnetic relaxation signal. The signal acquired by the noise measurement channel (usually composed of a reference coil located far from the sample area or using reverse winding) mainly includes environmental background magnetic field fluctuations and system common-mode interference, and is called the reference background noise.Due to slight asymmetries in the physical space or circuitry between the two channels, the reference background noise cannot be directly equated to the noise component in the signal measurement channel. Furthermore, during the silent period before magnetization excitation or in the tail region where the magnetic nanoparticle signal has completely decayed, the measurement data of the signal and noise measurement channels can be fitted and analyzed using the least squares or recursive least squares method. Based on the fitting analysis results, the background noise coupling coefficient between the two channels is determined. Then, based on the calculated coupling coefficient and the real-time acquired reference background noise, the actual measurement background noise in the signal measurement channel is reconstructed. For example, the reference background noise captured by the noise measurement channel is multiplied by the coupling coefficient, and a possible DC bias term is added to accurately simulate the measurement background noise superimposed on the signal measurement channel at this moment. Finally, the reconstructed measurement background noise is subtracted from the initial magnetic relaxation signal to obtain the interference-free magnetic relaxation signal of the magnetic nanoparticle under test. After this processing, the weak particle relaxation signal, originally submerged in strong background noise, is clearly extracted, significantly improving the measurement accuracy of the magnetic relaxation signal.

[0023] In this embodiment of the invention, the state acquisition unit may include an excitation-related state acquisition unit for acquiring magnetization excitation state data, such as... Figure 2 The diagram illustrates the arrangement of certain units (magnetization excitation unit, measurement area, magnetization coil, reference magnetic field state acquisition unit, extremely weak magnetic field measurement unit, and residual field processing unit) in a magnetic relaxation signal measurement system. The magnetization excitation unit generates the magnetic field. The state acquisition unit includes a reference magnetic field state acquisition unit for acquiring background residual magnetic field state data and an extremely weak magnetic field measurement unit for acquiring the operating state data of the extremely weak magnetic field measurement device. The data acquired by the excitation-related state acquisition unit, the reference magnetic field state acquisition unit, and the extremely weak magnetic field measurement unit are timestamped. The extremely weak magnetic field measurement unit can be positioned to detect the field-free magnetic response of the magnetic nanoparticles under test. For example, the extremely weak magnetic field measurement unit can be located to one side of the location of the magnetic nanoparticles under test (sample carrier unit), with its sensitive direction consistent with the main direction of the magnetic response, or having a predetermined response relationship with the magnetic response direction. The reference magnetic field state acquisition unit is positioned to reflect the residual magnetic field of the measurement area. Preferably, under the same particle magnetic response conditions, the particle magnetic response component detected by the reference magnetic field state acquisition unit is smaller than that detected by the extremely weak magnetic field measurement unit, so that the reference magnetic field state acquisition unit is mainly used to characterize the background residual magnetic field of the measurement area. When the reference magnetic field state acquisition unit can still detect a portion of the magnetic response, the response relationship between the reference magnetic field state acquisition unit and the magnetic nanoparticle under test and the background magnetic source can be determined by adjusting its spatial position and sensitive direction relative to the magnetic nanoparticle under test, or by employing a calibration method. During data processing, the particle magnetic response components in the reference channel can be corrected based on the response relationship.

[0024] By applying the technical solution of this embodiment, the acquisition time of the magnetic relaxation signal is dynamically determined based on multi-dimensional state information. On the one hand, this avoids the problem of early loss of strong signals from magnetic nanoparticles due to excessively long fixed waiting times, significantly improving the temporal resolution and signal-to-noise ratio of signal acquisition. On the other hand, it prevents the introduction of strong interference when the system is not fully stable due to insufficient waiting time, ensuring that the acquisition window is always opened at the optimal state with the lowest system noise and the purest signal, thereby improving the detection sensitivity and accuracy of weak magnetic relaxation signals. By utilizing the background noise coupling coefficient between the signal measurement channel and the noise measurement channel through the data acquisition and processing unit, the reference background noise is converted into accurate measurement background noise and separated. This accurately removes residual background noise and environmental interference, extracting high-fidelity interference-free magnetic relaxation signals of the magnetic nanoparticles under test from the complex initial signal, further improving the measurement accuracy of the magnetic relaxation signal.

[0025] In an embodiment of the present invention, optionally, the joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information by executing the following steps: determining whether the multi-dimensional state information meets the magnetic relaxation signal measurement conditions, wherein it is determined whether the rate of change of current in the magnetization excitation circuit after the magnetization excitation is removed is less than or equal to a preset current threshold, whether the rate of change of amplitude of the background residual magnetic field is less than or equal to a preset magnetic field threshold, and whether the extremely weak magnetic field measuring device has entered the allowable measurement state. If the rate of change of current in the magnetization excitation circuit is less than or equal to the preset current threshold, the rate of change of amplitude of the background residual magnetic field is less than or equal to the preset magnetic field threshold, and the extremely weak magnetic field measuring device has entered the allowable measurement state, then it is determined that the multi-dimensional state information meets the magnetic relaxation signal measurement conditions; otherwise, it is determined that the multi-dimensional state information does not meet the magnetic relaxation signal measurement conditions. If the multi-dimensional state information meets the magnetic relaxation signal measurement conditions, the time when the magnetic relaxation signal measurement conditions are met is determined as the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test.

[0026] Specifically, the following formula is used to determine whether the multi-dimensional state information meets the measurement conditions for magnetic relaxation signals:

[0027]

[0028] in, For the current moment The loop current of the magnetization excitation circuit, For the current moment The rate of change of current in the magnetization excitation circuit, For preset current threshold, For the current moment The rate of change of the amplitude of the background residual magnetic field To preset the magnetic field threshold, if both the rate of change of current and the rate of change of the amplitude of the background residual magnetic field satisfy the conditions of the above formula, and the extremely weak magnetic field measuring device enters the allowable measurement state, then the multi-dimensional state information is determined to meet the magnetic relaxation signal measurement conditions. If any of the above conditions are not met, then the multi-dimensional state information is determined not to meet the magnetic relaxation signal measurement conditions. Finally, when the multi-dimensional state information meets the magnetic relaxation signal measurement conditions, the earliest time that meets the magnetic relaxation signal measurement conditions is determined as the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test. This embodiment of the invention dynamically determines the acquisition time of the magnetic relaxation signal based on the multi-dimensional state information. On the one hand, it avoids the problem of early loss of strong signals from magnetic nanoparticles due to excessively long fixed waiting time, significantly improving the temporal resolution and signal-to-noise ratio of signal acquisition. On the other hand, it prevents the introduction of strong interference when the system is not fully stable due to insufficient waiting time, ensuring that the opening time of the acquisition window is always at the optimal state of lowest system noise and purest signal, thereby improving the detection sensitivity and accuracy of weak magnetic relaxation signals.

[0029] In an embodiment of the present invention, optionally, the joint determination and timing control unit is used to determine whether the extremely weak magnetic field measuring device has entered a permissible measurement state by performing the following steps: determining the recovery state evaluation value of the extremely weak magnetic field measuring device: ,in, The recovery state evaluation value of the extremely weak magnetic field measuring device, , and They are respectively weighting coefficients, The measurement information of the extremely weak magnetic field measuring device at the current time t, The measurement deviation between the measurement information of the extremely weak magnetic field measuring device at the current time t and the baseline information. The noise level of the extremely weak magnetic field measuring device at the current time t, , and The corresponding normalized scales are measurement deviation, measurement information change rate, and noise level; it is determined whether the recovery state evaluation value is less than or equal to the preset recovery state threshold. If so, the extremely weak magnetic field measuring device is determined to have entered the allowable measurement state; otherwise, the extremely weak magnetic field measuring device is determined not to have entered the allowable measurement state.

[0030] Among them, whether the extremely weak magnetic field measuring device has entered the allowable measurement state refers to whether the device has left the saturated or unstable state and entered the allowable measurement range.

[0031] Specifically, the recovery state evaluation value of the extremely weak magnetic field measuring device is determined based on the measurement information of the extremely weak magnetic field measuring device at the current time t, the measurement deviation between the measurement information and the baseline information, and the noise level. ,like If the extremely weak magnetic field measuring device is in the allowable measurement state, then it is determined that the device has entered the allowable measurement state. If the extremely weak magnetic field measuring device is not in the allowable measurement state, then it is determined that the device has not entered the measurement state. A preset recovery state threshold is set according to actual needs. This embodiment of the invention comprehensively characterizes the dynamic recovery process of an extremely weak magnetic field measuring device after excitation by introducing three key dimensions: measurement deviation, rate of change of measurement information, and noise level. Measurement deviation reflects the degree to which the device deviates from its linear operating region, the rate of change characterizes the speed at which the device tends to stabilize, and the noise level directly reflects the reliability of the device's signal. This multi-dimensional comprehensive consideration can more accurately capture minute nonlinear distortions or transient instabilities within the device, thereby improving the accuracy of determining whether the extremely weak magnetic field measuring device is allowed to enter the measurement state.

[0032] In embodiments of the present invention, optionally, such as Figure 3 As shown, the multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system further includes: a residual field processing unit, which is used to determine whether the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is greater than a preset time threshold when the multi-dimensional state information does not meet the magnetic relaxation signal measurement conditions. If so, it determines a processing action to reduce the influence of the residual magnetic field in the magnetized region based on the magnetization excitation state data of the magnetized region where the magnetic nanoparticle to be measured is located and the background residual magnetic field state data of the background magnetic field. Based on the processing action, it performs magnetic field modulation processing on the magnetized region. The joint determination and timing control unit is also used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle to be measured based on the multi-dimensional state information of the magnetized region where the magnetic nanoparticle to be measured is located after magnetic field modulation processing.

[0033] The preset time threshold is set according to actual needs. Specifically, if the multi-dimensional state information does not meet the measurement conditions for the magnetic relaxation signal, and the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is greater than the preset time threshold, the residual field processing unit determines the specific processing action to reduce the influence of the residual magnetic field in the magnetized region based on the magnetization excitation state data of the magnetized region where the magnetic nanoparticles to be measured are located and the background residual magnetic field state data of the background magnetic field. This unit analyzes the historical waveform of the excitation current and the coil inductance characteristics in the magnetization excitation state data, and combines the residual magnetic field vector fed back by the reference sensor in the background residual magnetic field state data, such as the amplitude, direction and rate of change of the residual magnetic field, as well as the relationship between the coil and the magnetic field, to determine the processing parameters such as the amplitude, polarity and application timing of the compensation current required to offset the current residual field. Based on the processing parameters, the processing action is determined. The determined processing action usually includes driving the compensation coil to generate a magnetic field opposite to the residual magnetic field; applying a controlled reverse current to the magnetization coil; switching the magnetization excitation circuit to a damped discharge, active demagnetization, energy recovery or high-resistance isolation state; or continuing to wait until the background magnetic field enters the calibrable range. The residual field processing unit then executes the aforementioned processing action, performing real-time magnetic field modulation processing on the magnetized region. Through this active compensation mechanism, the decay process of the residual magnetic field within the magnetized region is forcibly accelerated, or the originally non-uniform and unstable background magnetic field is quickly pulled back to near zero field or a working range with good linearity. This modulation processing effectively eliminates long-tail interference caused by the hysteresis effect of the magnetic shielding cylinder or the residual magnetism of environmental ferromagnetic materials, creating a clean electromagnetic environment for subsequent magnetic relaxation signal measurement. Finally, after the magnetic field modulation processing is completed, the joint judgment and timing control unit performs a secondary evaluation of the magnetic relaxation signal acquisition time based on the updated multi-dimensional state information of the magnetized region where the magnetic nanoparticles to be measured are located. Only when the multi-dimensional state information after modulation processing again meets the various index requirements for magnetic relaxation signal measurement will the joint judgment and timing control unit finally determine and output the magnetic relaxation signal acquisition time, triggering the data acquisition and processing unit to start working. This mechanism ensures that even in harsh natural environments or with slow hardware response, the system can still obtain a high-quality measurement window through active modulation, significantly improving the system's adaptability and measurement success rate. In this embodiment of the invention, the residual field processing unit can be an independently set processing coil or a reused magnetization excitation unit. By applying a reverse current, a controlled decay current or other processing current to the magnetization excitation unit, residual magnetic field compensation, rapid demagnetization or loop energy release can be achieved.

[0034] In an embodiment of the present invention, optionally, the joint determination and timing control unit is further configured to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located at the next time corresponding to the current time when the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is less than or equal to the preset time threshold.

[0035] Specifically, if the time interval between the triggering moment of the magnetization excitation cancellation signal and the current moment is less than or equal to a preset time threshold, the system continues to search for the earliest moment when the multi-dimensional state information of the magnetized region where the magnetic nanoparticle to be tested is located simultaneously satisfies the magnetic relaxation signal measurement conditions. This earliest moment is taken as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle to be tested. This embodiment of the invention, by employing a dynamic judgment strategy based on the prediction of the state at the next moment within a preset time threshold, can keenly capture the instant when the physical field has just reached a stable state, rather than passively waiting for a conservative, long fixed safety time. This not only preserves the rapidly decaying high-frequency early components in the magnetic nanoparticle relaxation signal but also shortens the cycle time of a single measurement, improving the overall detection efficiency.

[0036] In an embodiment of the present invention, optionally, the joint determination and timing control unit is configured to determine the moment when the magnetic relaxation signal measurement conditions are met as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle under test by performing the following steps: acquiring the historical magnetic response amplitude of the magnetic nanoparticle under test at multiple historical sampling points, determining the predicted magnetic response amplitude of the magnetic nanoparticle under test at the moment when the magnetic relaxation signal measurement conditions are met based on the historical magnetic response amplitude; determining the measurement noise level based on the measurement information of the extremely weak magnetic measurement device before the magnetization excitation is applied, and determining the background noise correction error of the magnetized region; determining the accuracy verification coefficient based on the predicted magnetic response amplitude, the measurement noise level, and the background noise correction error. ,in, To verify the accuracy of the coefficients, The timing for satisfying the magnetic relaxation signal measurement conditions The predicted magnetic response amplitude, The timing for satisfying the magnetic relaxation signal measurement conditions Measurement noise level, The timing for satisfying the magnetic relaxation signal measurement conditions The background noise correction error; based on the accuracy verification coefficient, the accuracy verification of the time that meets the magnetic relaxation signal measurement conditions is performed, and the time that meets the magnetic relaxation signal measurement conditions and passes the accuracy verification is determined as the magnetic relaxation signal acquisition time of the magnetic nanoparticle to be measured.

[0037] Specifically, the joint determination and timing control unit acquires the historical magnetic response amplitudes of the magnetic nanoparticle under test at multiple historical sampling points. These historical data reflect the attenuation trend of the magnetic relaxation signal of the magnetic nanoparticle in previous excitation cycles or early stages of the current cycle. Based on these historical magnetic response amplitudes, a curve fitting algorithm is used to extrapolate the magnetic response amplitude of the magnetic nanoparticle under test at the moment when the magnetic relaxation signal measurement conditions are about to be met, thereby determining the predicted magnetic response amplitude at that moment. Secondly, the current measurement noise level is determined based on the measurement information of the extremely weak magnetic field measurement device before the application of magnetization excitation. Since the period before the application of excitation usually represents the background noise state of the system, the current electronic noise and environmental noise floor can be quantified as the measurement noise level by analyzing the standard deviation of voltage fluctuation or power spectral density during this period. At the same time, the background magnetic field monitoring data of the magnetized region is combined to determine the background noise correction error, which reflects the uncertainty component remaining after offsetting environmental interference. Subsequently, the joint decision-making and timing control unit uses the aforementioned determined predicted magnetic response amplitude, measurement noise level, and background noise correction error to calculate an accuracy verification coefficient. This accuracy verification coefficient is essentially a dynamic signal-to-noise ratio index specific to a given moment. If the accuracy verification coefficient... ,in, If the minimum signal-to-noise ratio is achieved, the moment that meets the magnetic relaxation signal measurement conditions is deemed to have passed the accuracy verification, and this moment is officially determined as the magnetic relaxation signal acquisition moment for the magnetic nanoparticle under test. Otherwise, the moment that meets the magnetic relaxation signal measurement conditions is deemed to have failed the accuracy verification. If the verification fails, the moment is discarded or the next moment is waited for to re-evaluate the magnetic relaxation signal acquisition moment. This embodiment of the invention, by introducing a ratio verification of the predicted magnetic response amplitude to noise and error, can intelligently avoid low-quality windows that, although the system is stable, have weak signals or excessive background correction residuals, ensuring that acquisition is only performed at the optimal time when the signal characteristics are most significant and noise interference is relatively minimal, thereby improving the measurement accuracy of the magnetic relaxation signal.

[0038] In an embodiment of the present invention, optionally, the data acquisition and processing unit is configured to determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel by performing the following steps: after applying and removing a magnetizing field in a measurement area in a blank area, synchronously acquiring the measurement channel signal sequence output by the measurement channel for the blank area and the reference channel signal sequence output by the reference channel for the background magnetic field of the measurement area; constructing a linear error function with the reference channel signal sequence as the independent variable and the measurement channel signal sequence as the dependent variable, solving for the proportionality coefficient that minimizes the sum of squared residuals of the linear error function, and using the proportionality coefficient as the background noise coupling coefficient between the signal measurement channel and the noise measurement channel.

[0039] Specifically, a blank sample without magnetic nanoparticles, such as pure water or air, or no object at all, is placed in the measurement area. Then, the excitation coil is driven to apply and remove a complete magnetization field excitation to the blank area. During this process, since no magnetic particles generate relaxation signals, the data acquired by the measurement channel consists purely of environmental background magnetic field interference, circuit thermal noise, and coil-induced eddy currents. Simultaneously, two key sequences are acquired: first, the measurement channel signal sequence output by the measurement channel (signal measurement channel) for the blank area, representing the noise component's representation in the signal + noise configuration; second, the reference channel signal sequence output by the reference channel (noise measurement channel) for the background magnetic field of the measurement area at the same moment, representing the pure... The environmental background interference sources are identified. Then, using the reference channel signal sequence as the independent variable and the measurement channel signal sequence as the dependent variable, a linear error function is constructed. This function describes how the noise in the reference channel is linearly mapped to the measurement channel. To find the most accurate mapping relationship, the unit uses a least squares algorithm to solve for it. Specifically, a specific scaling factor is found such that the sum of the squares of the differences (i.e., residuals) between the reference channel signal sequence and the measurement channel signal sequence after multiplying this scaling factor by the reference channel signal sequence is minimized. This scaling factor that minimizes the error is determined as the background noise coupling coefficient between the signal measurement channel and the noise measurement channel. This coefficient reflects the comprehensive differences in geometric position, sensitivity, and circuit gain between the two sensors or coils in real time. This embodiment of the invention, by conducting on-site measurements using a blank area before each measurement, can capture the true transfer function relationship between the two channels at the current moment. This dynamic fitting based on measured data ensures that when subtracting background noise from the noisy signal, the weak magnetic nanoparticle signal can be preserved to the greatest extent, avoiding noise residue or excessive signal attenuation caused by coupling factor mismatch, thereby improving the measurement accuracy of the magnetic relaxation signal.

[0040] In embodiments of the present invention, optionally, such as Figure 3 As shown, the multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system further includes a parameter update unit. The parameter update unit is used to determine the abnormal state category of the magnetization region based on the multi-dimensional state information and the initial magnetic relaxation signal. The abnormal state category includes at least one of magnetization excitation state abnormality, background residual magnetic field state abnormality, extremely weak magnetic measurement device abnormality, and magnetic relaxation signal quality abnormality. Based on the abnormal state category, the unit determines the magnetization excitation condition configuration parameters for the next magnetic relaxation signal measurement cycle and updates the magnetization excitation condition of the magnetic nanoparticles to be measured for the next magnetic relaxation signal measurement cycle based on the magnetization excitation condition configuration parameters.

[0041] Specifically, the parameter update unit receives multi-dimensional state information from the joint judgment and timing control unit and the initial magnetic relaxation signal output by the data acquisition and processing unit. Based on this data, it performs in-depth analysis of the magnetization region to determine the abnormal state category of the magnetization region. For example, if the excitation current waveform is distorted or saturated, it is determined that the magnetization excitation state is abnormal; if the background magnetic field cannot return to zero for a long time after the excitation is removed or there is low-frequency drift, it is determined that the background residual magnetic field state is abnormal; if the sensor output noise floor suddenly increases or the linearity exceeds the standard, it is determined that the extremely weak magnetic field measurement device is abnormal; if the signal-to-noise ratio of the initial magnetic relaxation signal is too low, the amplitude is abnormal, or the attenuation curve does not conform to physical laws, it is determined that the magnetic relaxation signal quality is abnormal. Secondly, after clarifying the abnormal state category, the parameter update unit determines the magnetization excitation condition configuration parameters for the next magnetic relaxation signal measurement cycle. For example, to address abnormal magnetization excitation states, the magnetization excitation parameters for rapid shutdown, damped discharge, active demagnetization, loop switching, or the next measurement cycle can be adjusted. To address abnormal background residual magnetic field states, the direction, amplitude, duration, or triggering conditions of residual field processing can be adjusted. To address abnormalities in the extremely weak magnetic field measurement device, the magnetization excitation intensity, sensor protection mode, operating parameters, or recovery judgment conditions can be adjusted. To address abnormal magnetic relaxation signal quality, the magnetization excitation amplitude or duration, sampling duration, effective detection window parameters, or the number of repeated measurements can be adjusted. When two or more states are simultaneously abnormal, parameter update methods corresponding to each abnormality category can be combined. The updated parameters are used for magnetization excitation, shutdown or discharge, residual field processing, sensor control, and data acquisition in the next measurement cycle. Parameter updates can employ recursive estimation, comparison of historical measurement results, or other methods capable of updating parameters for the next measurement cycle based on the current measurement state. Finally, the parameter update unit updates the magnetization excitation conditions of the magnetic nanoparticles under test in real time according to the magnetization excitation configuration parameters for the next magnetic relaxation signal measurement cycle. The system no longer mechanically repeats the same measurement process, but dynamically adjusts the measurement process for the next cycle based on the measurement results of the previous cycle, ensuring that each measurement is performed in the optimal state within the current system's capabilities. This embodiment of the invention, by introducing a parameter update unit, establishes a real-time self-correcting closed loop that can automatically identify and compensate for various non-ideal factors. This not only reduces the experimental failure rate and retest costs caused by environmental interference, but also ensures that the system can always output stable, reliable, and high-quality magnetic relaxation signals in complex and ever-changing application scenarios. The magnetic relaxation signal refers to the weak magnetic field signal released by magnetic nanoparticles as their magnetic moments gradually recover from an ordered state to a disordered thermal equilibrium state after the external magnetic field is removed.

[0042] In an embodiment of the present invention, optionally, the data acquisition and processing unit is configured to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time by performing the following steps: determining a magnetic relaxation signal acquisition window based on the magnetic relaxation signal acquisition time, acquiring a coarse magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition window, and filtering out the initial magnetic relaxation signal from the coarse magnetic relaxation signal.

[0043] Specifically, the data acquisition and processing unit receives the magnetic relaxation signal acquisition time determined by the joint decision and timing control unit. Based on this time, it extends forward by a specific time span to determine a magnetic relaxation signal acquisition window. This window not only includes the expected signal peak period but also reserves sufficient baseline acquisition time and signal tail decay time to ensure that the complete physical process is captured. Then, within the determined acquisition window time, the data acquisition and processing unit continuously samples the signal measurement channel to obtain the original coarse magnetic relaxation signal. Since the system has just experienced a high-intensity magnetization excitation at this time, The acquired data often contains residual eddy current interference from the excitation coil, transient circuit response, and environmental background noise. The data acquisition and processing unit then uses preset digital filters, such as bandpass filters, to filter out high-frequency electronic noise and power frequency interference from the coarse magnetic relaxation signal, and removes DC offset. Simultaneously, denoising techniques such as moving average or wavelet transform can be used to smooth the signal curve. After a series of screening and processing steps, the pure data sequence that truly reflects the magnetic moment recovery process of the measured magnetic nanoparticles is ultimately retained and determined as the initial magnetic relaxation signal, used for subsequent particle size inversion or concentration calculation. This embodiment of the invention avoids invalid full-time sampling by introducing an acquisition window, saving storage and computing resources. Through a secondary screening process from the coarse signal to the initial signal, the signal is further purified, improving the measurement accuracy of the subsequent magnetic relaxation signal. It should be noted that the magnetic relaxation signal acquisition window can be used to control the data acquisition and processing unit to start effective acquisition after the earliest effective detection time, or it can be used to mark, filter, truncate, or extract corresponding data segments from continuously recorded complete time-series data.

[0044] In this embodiment of the invention, when the system has multiple measurement channels, multiple measurement positions, or a moving scanning mechanism, an experimental system matrix between the measurement area and each magnetic sensor can be established, and the equivalent magnetic moment, concentration distribution, or spatial position of the particles can be estimated based on the magnetic response characteristics within the effective window. Spatial reconstruction can employ magnetic dipole inversion, regularized least squares, sparse reconstruction, Bayesian inversion, nonnegativity constraints, or iterative optimization. Spatial reconstruction is not a necessary module of the basic measurement scheme; it can be omitted when only single-point relaxation parameter measurement is performed.

[0045] In this embodiment of the invention, at least one of the following can be extracted from the interference-free magnetic relaxation signal: peak value, effective detection window initial amplitude, integral area, effective relaxation time, single-exponential or multi-exponential fitting parameters, signal-to-noise ratio, and fitting residual.

[0046] It should be noted that each unit in the above-mentioned multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system can transmit data and information through wireless communication technology.

[0047] In one embodiment, a multi-state joint determination method for measuring magnetic relaxation signals of magnetic nanoparticles is provided. This method is applied to a multi-state joint determination magnetic relaxation signal measurement system for magnetic nanoparticles as described in any of the above embodiments. The method includes: a state acquisition unit responding to a magnetization excitation cancellation signal of the magnetic nanoparticle under test after applying magnetization excitation, acquiring multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time, wherein the multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of the background magnetic field, and operating state data of the extremely weak magnetic field measuring device; and a joint determination and timing control unit based on the... The multi-dimensional state information is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test. The data acquisition and processing unit acquires the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determines the reference background noise of the background magnetic field in the noise measurement channel, determines the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determines the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separates the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise.

[0048] Specifically, at the instant magnetization excitation is applied to the magnetic nanoparticles under test and then removed, the state acquisition unit simultaneously collects multi-dimensional state information of the magnetized region. This information covers three key aspects: first, magnetization excitation state data, reflecting the residual eddy currents and magnetic field decay after the excitation coil current is removed; second, background residual magnetic field state data, used to monitor the fluctuation and residual level of the ambient magnetic field after excitation; and third, the operating state data of the extremely weak magnetic field measurement device, including sensor temperature, bias voltage, and background noise level, to ensure that the measurement hardware is in a stable operating condition. Subsequently, the joint judgment and timing control unit receives the above multi-dimensional state information and dynamically determines the optimal magnetic relaxation signal acquisition time by analyzing whether the data in each dimension reaches a preset stability threshold. For example, the unit only issues an acquisition command when the excitation residual magnetic field decays to a safe range, the ambient background magnetic field tends to stabilize, and the sensor noise is low. Determining this moment avoids invalid or distorted data acquired during periods of system instability. Subsequently, based on a predetermined acquisition time, the data acquisition and processing unit acquires the initial magnetic relaxation signal, which includes the response of the magnetic nanoparticle under test and environmental interference, in the signal measurement channel. Simultaneously, the unit acquires a reference background noise that reflects only environmental interference in a specially configured noise measurement channel. To accurately eliminate interference, the unit uses a pre-calibrated or real-time calculated background noise coupling coefficient, which characterizes the proportional relationship between the noise channel and the signal channel in response to the environmental magnetic field, to convert the reference background noise into the equivalent measurement background noise of the signal measurement channel. Finally, the data acquisition and processing unit performs a signal separation operation, which subtracts the calculated measurement background noise from the initial magnetic relaxation signal or cancels it out using an adaptive filtering algorithm, thereby removing environmental magnetic field interference and system common-mode noise, and ultimately restoring a pure, interference-free magnetic relaxation signal generated only by the magnetic nanoparticle under test. This invention dynamically determines the acquisition time of the magnetic relaxation signal based on multi-dimensional state information. On the one hand, it avoids the problem of early loss of strong signals from magnetic nanoparticles due to excessively long fixed waiting times, significantly improving the temporal resolution and signal-to-noise ratio of signal acquisition. On the other hand, it prevents the introduction of strong interference when the system is not fully stable due to insufficient waiting time, ensuring that the acquisition window is always opened at the optimal state with the lowest system noise and the purest signal, thereby improving the detection sensitivity and accuracy of weak magnetic relaxation signals. By utilizing the background noise coupling coefficient between the signal measurement channel and the noise measurement channel through the data acquisition and processing unit, the reference background noise is converted into accurate measurement background noise and separated. This accurately removes residual background noise and environmental interference, extracting high-fidelity interference-free magnetic relaxation signals of the magnetic nanoparticles under test from the complex initial signal, further improving the measurement accuracy of the magnetic relaxation signal.

[0049] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system, characterized in that, include: Status acquisition unit, joint decision and timing control unit, data acquisition and processing unit; The state acquisition unit is used to respond to the magnetization excitation cancellation signal of the magnetic nanoparticle under test after applying magnetization excitation, and to acquire multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time. The multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of background magnetic field and working state data of extremely weak magnetic field measurement device. The joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information. The data acquisition and processing unit is used to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determine the reference background noise of the background magnetic field in the noise measurement channel, determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determine the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separate the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise; wherein, the data acquisition and processing unit is used to determine the background noise coupling coefficient between the signal measurement channel and the noise measurement channel by performing the following steps: after applying and removing the magnetizing field in the measurement area in the blank area, synchronously acquire the measurement channel signal sequence output by the measurement channel for the blank area and the reference channel signal sequence output by the reference channel for the background magnetic field of the measurement area; construct a linear error function with the reference channel signal sequence as the independent variable and the measurement channel signal sequence as the dependent variable, solve for the proportionality coefficient that minimizes the sum of squared residuals of the linear error function, and use the proportionality coefficient as the background noise coupling coefficient between the signal measurement channel and the noise measurement channel.

2. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 1, characterized in that, The joint determination and timing control unit is used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information by executing the following steps: Determine whether the multi-dimensional state information meets the magnetic relaxation signal measurement conditions. Specifically, determine whether the rate of change of current in the magnetization excitation circuit after the magnetization excitation is removed is less than or equal to a preset current threshold, whether the rate of change of amplitude of the background residual magnetic field is less than or equal to a preset magnetic field threshold, and whether the extremely weak magnetic field measuring device has entered the allowable measurement state. If the rate of change of current in the magnetization excitation circuit is less than or equal to the preset current threshold, the rate of change of amplitude of the background residual magnetic field is less than or equal to the preset magnetic field threshold, and the extremely weak magnetic field measuring device has entered the allowable measurement state, then the multi-dimensional state information is determined to meet the magnetic relaxation signal measurement conditions. Otherwise, the multi-dimensional state information is determined not to meet the magnetic relaxation signal measurement conditions. When the multi-dimensional state information satisfies the magnetic relaxation signal measurement conditions, the moment when the magnetic relaxation signal measurement conditions are met is determined as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle under test.

3. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 2, characterized in that, The joint determination and timing control unit is used to determine whether the extremely weak magnetic field measuring device has entered the allowable measurement state by executing the following steps: Determine the recovery status evaluation value of the extremely weak magnetic field measuring device: ,in, The recovery state evaluation value of the extremely weak magnetic field measuring device, , and They are respectively weighting coefficients, The measurement information of the extremely weak magnetic field measuring device at the current time t, The measurement deviation between the measurement information of the extremely weak magnetic field measuring device at the current time t and the baseline information. The noise level of the extremely weak magnetic field measuring device at the current time t, , and This corresponds to the normalized scales of measurement bias, rate of change of measurement information, and noise level. If the recovery state evaluation value is less than or equal to the preset recovery state threshold, then the extremely weak magnetic field measuring device is determined to have entered the allowable measurement state; otherwise, the extremely weak magnetic field measuring device is determined not to have entered the allowable measurement state.

4. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 2, characterized in that, Also includes: Residual field processing unit; The residual field processing unit is used to determine whether the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is greater than a preset time threshold when the multi-dimensional state information does not meet the magnetic relaxation signal measurement conditions. If so, it determines a processing action to reduce the influence of the residual magnetic field in the magnetized region based on the magnetization excitation state data of the magnetized region where the magnetic nanoparticle to be measured is located and the background residual magnetic field state data of the background magnetic field. Based on the processing action, it performs magnetic field regulation processing on the magnetized region. The joint determination and timing control unit is also used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information of the magnetized region where the magnetic nanoparticle under test is located after magnetic field modulation processing.

5. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 4, characterized in that, The joint determination and timing control unit is also used to determine the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located at the next time corresponding to the current time when the time interval between the triggering time of the magnetization excitation cancellation signal and the current time is less than or equal to the preset time threshold.

6. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 2, characterized in that, The joint determination and timing control unit is used to determine the moment when the magnetic relaxation signal measurement conditions are met as the magnetic relaxation signal acquisition moment of the magnetic nanoparticle under test by executing the following steps: The historical magnetic response amplitude of the magnetic nanoparticle under test at multiple historical sampling points is obtained, and the predicted magnetic response amplitude of the magnetic nanoparticle under test at the moment when the magnetic relaxation signal measurement conditions are met is determined based on the historical magnetic response amplitude. The measurement noise level is determined based on the measurement information from the extremely weak magnetic measuring device prior to the application of magnetization excitation, and the background noise correction error in the magnetized region is determined. The accuracy verification coefficient is determined based on the predicted magnetic response amplitude, the measured noise level, and the background noise correction error. ,in, To verify the accuracy of the coefficients, The timing for satisfying the magnetic relaxation signal measurement conditions The predicted magnetic response amplitude, The timing for satisfying the magnetic relaxation signal measurement conditions Measurement noise level, The timing for satisfying the magnetic relaxation signal measurement conditions Background noise correction error; The accuracy of the time that meets the magnetic relaxation signal measurement conditions is verified based on the accuracy verification coefficient. The time that meets the magnetic relaxation signal measurement conditions and passes the accuracy verification is determined as the magnetic relaxation signal acquisition time of the magnetic nanoparticle to be measured.

7. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 1, characterized in that, It also includes a parameter update unit; The parameter update unit is used to determine the abnormal state category of the magnetized region based on the multi-dimensional state information and the initial magnetic relaxation signal. The abnormal state category includes at least one of magnetization excitation state abnormality, background residual magnetic field state abnormality, extremely weak magnetic measurement device abnormality, and magnetic relaxation signal quality abnormality. Based on the abnormal state category, the unit determines the magnetization excitation condition configuration parameters for the next magnetic relaxation signal measurement cycle and updates the magnetization excitation condition of the magnetic nanoparticles to be measured for the next magnetic relaxation signal measurement cycle based on the magnetization excitation condition configuration parameters.

8. The magnetic nanoparticle magnetic relaxation signal measurement system based on multi-state joint determination according to claim 1, characterized in that, The data acquisition and processing unit is used to acquire the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time by performing the following steps: The magnetic relaxation signal acquisition window is determined based on the magnetic relaxation signal acquisition time. The rough magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel is acquired based on the magnetic relaxation signal acquisition window. The initial magnetic relaxation signal is then selected from the rough magnetic relaxation signal.

9. A method for measuring magnetic relaxation signals of magnetic nanoparticles based on multi-state joint determination, characterized in that, The method is applied to the multi-state joint determination magnetic nanoparticle magnetic relaxation signal measurement system as described in any one of claims 1-8, and the method includes: The state acquisition unit responds to the magnetization excitation cancellation signal of the magnetic nanoparticle under test after the magnetization excitation is applied, and acquires multi-dimensional state information of the magnetization region where the magnetic nanoparticle under test is located in real time. The multi-dimensional state information includes magnetization excitation state data, background residual magnetic field state data of background magnetic field and working state data of extremely weak magnetic measurement device. The joint judgment and timing control unit determines the magnetic relaxation signal acquisition time of the magnetic nanoparticle under test based on the multi-dimensional state information; The data acquisition and processing unit acquires the initial magnetic relaxation signal of the magnetic nanoparticle under test in the signal measurement channel based on the magnetic relaxation signal acquisition time, determines the reference background noise of the background magnetic field in the noise measurement channel, determines the background noise coupling coefficient between the signal measurement channel and the noise measurement channel, determines the measurement background noise of the signal measurement channel based on the background noise coupling coefficient and the reference background noise, and separates the interference-free magnetic relaxation signal of the magnetic nanoparticle under test from the initial magnetic relaxation signal based on the measurement background noise. Specifically, after applying and removing the magnetizing field in the measurement region (which is in a blank area), the data acquisition and processing unit simultaneously acquires the measurement channel signal sequence output by the measurement channel for the blank area and the reference channel signal sequence output by the reference channel for the background magnetic field of the measurement region. Using the reference channel signal sequence as the independent variable and the measurement channel signal sequence as the dependent variable, a linear error function is constructed. The proportionality coefficient that minimizes the sum of squared residuals of the linear error function is then calculated and used as the background noise coupling coefficient between the signal measurement channel and the noise measurement channel.

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