Precision Measurement Device and Method for Liquid Flow Velocity Based on Multichannel SERF Atomic Magnetometer

Abstract

This invention discloses a precision liquid flow velocity measurement device and method based on a multi-channel SERF atomic magnetometer, comprising: a laser generating module, a beam collimating module, a linear polarizer, a circular polarizer, a Powell prism, a cylindrical mirror, an atomic gas cell, a detector array, and a liquid flow channel disposed above the atomic gas cell and containing magnetic particles within the liquid flow channel. This multi-channel atomic magnetometer can detect positional changes of magnetic particles in the liquid, thereby achieving precise measurement of liquid flow velocity. The SERF atomic magnetometer has high sensitivity and can effectively detect weak magnetic field changes, which is beneficial for detecting slow changes in liquid flow velocity.

Description

Technical Field

[0001] This invention relates to the field of precision measurement of liquid flow velocity, and specifically to a device and method for precision measurement of liquid flow velocity based on a multi-channel spin-free exchange (SERF) atomic magnetometer. Background Technology

[0002] An atomic magnetometer is a highly sensitive quantum precision instrument for measuring magnetic fields. High-sensitivity magnetic field measurements have wide applications in fields such as biomedicine, geophysics, and space technology.

[0003] Recent research on biocompatible magnetic particles offers the potential for labeling in flexible, weakly magnetic applications, enabling the detection, capture, separation, and manipulation of biomolecules and cells within magnetic fields. The primary role of these magnetic particles is to be encapsulated in suitable biocompatible materials and introduced into biological systems as biosensors. After biolabeling, these magnetic particles can be manipulated by external magnetic fields for the delivery of therapeutic drugs, genes, and radionuclides, as well as for magnetic resonance imaging. Traditional techniques for detecting magnetic nanoparticles include superconducting quantum interference devices (SQUIDs); however, SQUIDs require liquid helium cooling to achieve superconductivity and are therefore expensive.

[0004] Spin exchange relaxation-free (SERF) atomic magnetometers are highly sensitive magnetic sensors operating in the spin-free interactive relaxation states of alkali metals. Due to their advantages such as ultra-high spatial resolution, ease of miniaturization, and ability to operate at room temperature, they have seen rapid development in recent years. SERF atomic magnetometers have achieved sensitivity levels reaching fT / Hz. 1 / 2 Its scale is suitable for research fields such as magnetocardiography, magnetoencephalography, and biocompatible magnetic particles.

[0005] Recently, atomic magnetometers have demonstrated excellent performance in the quantitative measurement of magnetic particles, such as the Mx atomic magnetometer for measuring magnetic particle diameter and the SERF magnetometer for measuring the concentration of magnetic nanoparticle dispersions. However, reports on the use of atomic magnetometers to measure the motion of magnetic particles are relatively few. Models for the transport of drugs labeled with magnetic nanoparticles via blood or other means are similar to models of magnetic particle motion. Research on measuring the flow of magnetic nanoparticles in liquids using SERF magnetometers could lay the foundation for addressing these issues.

[0006] Currently, most liquid flow rate measurements are performed using mechanical sensitive components. This method is often affected by factors such as liquid concentration and ambient temperature, limiting measurement accuracy. Furthermore, mechanical components are unsuitable for measurement in some biological and chemical fields. Flow meters based on atomic spin measurement, however, directly measure the magnetic field excited by target particles, and the measurement results are unaffected by numerous external factors. Summary of the Invention

[0007] To address the problems of existing technologies, this invention provides a precision liquid flow velocity measurement device and method based on a multi-channel SERF atomic magnetometer. This multi-channel atomic magnetometer can detect the positional changes of magnetic particles in a liquid, thereby achieving the purpose of precisely measuring liquid flow velocity.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A precision liquid flow velocity measurement device based on a multi-channel SERF atomic magnetometer, the atomic magnetometer device comprising: a laser generating module, a beam collimating module, a linear polarizer, a circular polarizer, a Powell prism, a cylindrical mirror, an atomic gas cell, a detector array, and a liquid flow channel disposed above the atomic gas cell and magnetic particles disposed within the liquid flow channel.

[0010] The laser generation module is used to generate initial linearly polarized light at 795nm.

[0011] The beam collimation module is used to adjust the shape of the beam spot to produce a non-divergent collimated beam spot.

[0012] The angle between the linear polarizer and the circular polarizer is fixed to achieve stable circularly polarized laser light.

[0013] Powell prisms are used to shape circular light spots into uniformly distributed linear light spots.

[0014] Cylindrical mirrors are used to reshape diffused linear light spots into non-divergent, uniform linear light spots, and within a certain range, they can be regarded as parallel light sources.

[0015] The atomic gas chamber is rectangular in shape and is located in the detection optical path to realize the interaction between atoms and light.

[0016] The photodetector array includes multiple photodetectors arranged in an array to receive probe light passing through the atomic gas cell, and then convert the optical signal into an electrical signal.

[0017] The flow channel is located directly above the atomic gas chamber.

[0018] The magnetic particles are ferromagnetic, easily magnetized particles. Before testing, they are polarized by a permanent magnet and embedded in foam spheres. The role of the foam spheres is to carry the particles along the flow.

[0019] As the magnetic particles pass above the atomic gas chambers, the magnetic field rapidly decreases with increasing distance due to the constantly changing distance, causing the magnetic field sensed by the atomic gas chambers to change accordingly. The magnetic particles are wrapped in foam spheres, which rotate randomly within the flow channel, causing the magnetic field sensed by the atomic gas chambers themselves to change constantly, resulting in an oscillating waveform. When a magnetic particle passes directly above a segment of the gas chamber, the signal strength measured by the magnetometer in that corresponding channel is the strongest; when the particle is far from the gas chamber, its influence on the magnetometer is negligible. Therefore, as the particle passes through the gas chamber, the magnetic field sensed by the magnetometer first increases and then decreases. Considering each independent channel, the change in the magnetic field sensed by the magnetometer resembles an envelope. By comparing the time intervals of the signal envelope peaks of different photodetectors, and combining this with the relative positions of the atomic gas chambers in each channel, the velocity of the magnetic particles can be calculated, thus yielding the flow velocity of the liquid.

[0020] A method for precise measurement of liquid flow velocity based on a multi-channel SERF atomic magnetometer, employing a precise liquid flow velocity measurement device based on a multi-channel SERF atomic magnetometer, includes the following steps:

[0021] 1) Fit the raw electrical signal data collected by each photodetector to obtain the data waveform diagram of each photodetector at different times;

[0022] 2) Normalize the data waveforms of each photodetector at different times, and use bandpass filtering to obtain the image envelope map. The image envelope map includes the image envelope of each photodetector. Use peak finding algorithm to find the time corresponding to the peak value of the image envelope of each photodetector. After multiple measurements, obtain the average time of each photodetector.

[0023] 3) Calculate the flow velocity of the liquid in the liquid channel by averaging the time of each photodetector.

[0024] In step 3), the flow velocity of the liquid in the liquid channel is calculated by averaging the time of each photodetector, specifically including:

[0025] The average times for each photodetector are T1, T2, ..., T n (where T1 < T2 < ... < T) n If the number of photodetectors is n and the spacing between them is X, then the flow velocity V can be predicted and calculated using the following expression:

[0026] V=[X / (T2-T1)+X / (T3-T2)+…+X / (T n -T n-1 )] / (n-1).

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The SERF atomic magnetometer has high sensitivity and can effectively detect extremely weak magnetic field changes, which is beneficial for detecting slow changes in liquid flow rate.

[0029] 2. A multi-channel photodetector array enables real-time monitoring of the position and velocity of magnetic particles. A single photodetector can detect the polarization intensity of the light signal in both perpendicular directions, which is highly efficient. The detection in both directions can be mutually calibrated, further improving the sensitivity of liquid flow velocity measurement and obtaining more comprehensive flow velocity change data.

[0030] 3. The detector and the target are completely non-contact during measurement, making it ideal for research fields such as blood flow velocity in clinical medicine and biology. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the optical path design for the invention device.

[0032] Figure 2 This is a schematic diagram of a precision liquid flow velocity measuring device.

[0033] Figure 3 The image shows the original signal (solid line) and the envelope fitting result (dashed line) measured in the x-direction of a certain channel in the invention example. Detailed Implementation

[0034] This invention presents an example of a four-channel array-type SERF atomic magnetometer, which can be used to measure the velocity of magnetic particles in a flow channel. This invention provides a new research method for measuring drug transport and metabolism in blood.

[0035] Referring to the attached diagram, Figure 1 This is a schematic diagram of the optical path of the present invention. After the laser is emitted, it passes through the beam collimation module 2 to obtain a parallel collimated light source. Then, the laser polarization is purified by a linear polarizer 3, and then high-purity circularly polarized light is obtained by a circular polarizer 4. After passing through the Powell prism 5, the circularly polarized light can form a rectangular stripe-shaped light spot with uniform intensity distribution. The light spot scans the long side cross-section of the rectangular atomic gas cell 7, and after transmission, it is received by an independent 1×4 array photodetector 8. Since the optical path length inside the atomic gas cell is very small, the signal interference caused by the thermal motion of the atoms can be ignored. The signal received by the photodetector can be approximated as the magnetic field signal detected by the independent gas cell.

[0036] Figure 2 The main functional modules of the present invention are shown, including a laser generating module 1, a beam collimation module 2, a linear polarizer 3, a circular polarizer 4, a Powell prism 5, a cylindrical mirror 6, an atomic gas cell 7, a detector array 8, a liquid flow channel 9, and magnetic particles 10.

[0037] In operation, the flow channel for which the flow velocity needs to be measured is fixed directly above the atomic gas chamber. Magnetic particles, encased in foam spheres and driven by a peristaltic pump, are placed inside the flow channel and reciprocate within it. Once the atomic magnetometers in each channel are functioning normally, an oscillating magnetic field envelope can be observed in each channel's atomic gas chamber as the magnetic particles pass through the flow channel. (See [link to documentation]). Figure 3 (d) Solid line portion. For example... Figure 3 As shown in (a), each photodetector receives a portion of the laser light passing through the atomic gas cell. The detector measures the magnetic signal sensed by the portion of the light source passing through the atomic gas cell. When particles flow over the atomic gas cell, the magnetic field signals sensed by different parts of the cell are asynchronous; see [reference needed]. Figure 3 (c) Due to the different positions of the atomic gas cells, the sensed envelopes in different channels differ in time. A comparison of the peak times of the signal envelopes from different photodetectors is shown below. Figure 3 (a) By obtaining the time interval and the coordinates of the particle at a certain moment, and combining the placement interval of the multi-channel photodetector, the velocity of the magnetic particle can be obtained, and then the flow velocity of the liquid can be obtained.

[0038] Figure 3 (b) and (d) show the data acquisition and analysis results of this invention; the data acquired from each channel is normalized, and the image envelope is obtained using bandpass filtering, as shown below. Figure 3 (b) As shown by the solid line; the peak time corresponding to the peak value of the image envelope of each photodetector is obtained by using the peak finding algorithm. After multiple measurements, the average time of each photodetector is obtained. Taking a certain measurement period as an example, the peak values ​​of the four channels correspond to the times T1, T2, T3, and T4 respectively (where T1 < T2 < T3 < T4). The placement interval between the photodetectors is X. Then the flow velocity V can be predicted and calculated by the following expression:

[0039] V=[X / (T2-T1)+X / (T3-T2)+X / (T4-T3)] / 3

[0040] Changing the peristaltic pump speed, which is directly proportional to the liquid flow rate, yields the fitting results of the flow rate and speed data measured in this example, as shown in [reference needed]. Figure 3 (b) The results show that the present invention can achieve non-contact liquid flow rate measurement.

Claims

1. A method for precise measurement of liquid flow velocity based on a multi-channel SERF atomic magnetometer, comprising the aforementioned precise liquid flow velocity measurement device based on a multi-channel SERF atomic magnetometer, including: The laser generating module, beam collimating module, linear polarizer, circular polarizer, Powell prism, cylindrical mirror, atomic gas cell, and detector array are arranged sequentially along the optical path. The cylindrical mirror is used to shape the linear light spot into a non-divergent, uniform linear light spot; The precise liquid flow rate measurement method includes the following steps: 1) Fit the raw electrical signal data collected by each photodetector to obtain the data waveform diagram of each photodetector at different times; 2) Normalize the data waveforms of each photodetector at different times, and use bandpass filtering to obtain the image envelope. The image envelope includes the image envelope of each photodetector. Use peak finding algorithm to find the time corresponding to the peak value of the image envelope of each photodetector. After multiple measurements, obtain the average time of each photodetector. 3) Calculate the flow velocity of the liquid in the liquid channel by averaging the time of each photodetector; In step 3), the flow velocity of the liquid in the liquid channel is calculated by averaging the time of each photodetector, specifically including: The average times for each photodetector are T1, T2, and T2, respectively. ,T n Where T1 < T2 < <T n If the number of photodetectors is n and the spacing between them is X, then the flow velocity V can be predicted and calculated using the following expression: V=[X / (T2-T1)+X / (T3-T2)+ +X / (T n -T n-1 )] / (n-1); Above the atomic gas chamber is a liquid flow channel and magnetic particles disposed within the liquid flow channel; the magnetic particles are encased in foam spheres and driven by a peristaltic pump to reciprocate within the flow channel; The linear polarizer and the circular polarizer have a fixed angle, which is used to output circularly polarized laser with stable polarization state. The Powell prism is used to shape a circular light spot into a uniformly distributed linear light spot; The detector array includes multiple photodetectors arranged in an array to receive probe light passing through the atomic gas cell and convert the probe light signal into an electrical signal.

2. The method for precise measurement of liquid flow velocity based on a multi-channel SERF atomic magnetometer according to claim 1, characterized in that, The laser generating module produces initial linearly polarized light.

3. The method for precise measurement of liquid flow velocity based on a multi-channel SERF atomic magnetometer according to claim 1, characterized in that, The beam collimation module is used to adjust the shape of the light spot to produce a non-divergent collimated light spot.

4. The method for precise measurement of liquid flow velocity based on a multi-channel SERF atomic magnetometer according to claim 1, characterized in that, The atomic gas chamber is rectangular in shape.

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