CN115753966A - Magnetic bead concentration measuring system and method regulated and controlled by alternating-current magnetic field - Google Patents
Magnetic bead concentration measuring system and method regulated and controlled by alternating-current magnetic field Download PDFInfo
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- CN115753966A CN115753966A CN202211531049.0A CN202211531049A CN115753966A CN 115753966 A CN115753966 A CN 115753966A CN 202211531049 A CN202211531049 A CN 202211531049A CN 115753966 A CN115753966 A CN 115753966A
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Abstract
The invention provides a system and a method for measuring the concentration of magnetic beads regulated and controlled by an alternating-current magnetic field, wherein the measuring method comprises the following steps: loading a solution to be measured on the surface of the quartz crystal oscillator with thickness shear vibration; applying an alternating-current magnetic field to magnetize the magnetic beads suspended in the solution to enable the magnetic beads to generate magnetization spin, and enabling the magnetic beads to generate friction with the solution; the friction force is transmitted to the surface of the quartz crystal through the solution and is subjected to motion synthesis with the vibration of the quartz crystal. The friction force disturbs the quartz crystal in oscillation, so that the motion signal of the magnetic beads is modulated on the oscillation signal of the quartz crystal to generate a synthesized vibration signal, and the magnetization spin motion signal of the magnetic beads can be extracted after the modulation signal is demodulated. And the concentration of the magnetic beads in the solution is detected by analyzing the intensity of the magnetic bead magnetization motion signal after extraction. The method can be used for measuring the concentration of the magnetic bead solution under various solution conditions, and has the characteristics of simplicity, rapidness and wide applicability.
Description
Technical Field
The invention relates to the technical field of detection instruments, in particular to a method and a device for measuring the concentration of magnetic beads regulated and controlled by an alternating-current magnetic field.
Background
Superparamagnetic nano materials are biological nano materials with the most development potential in recent 20 years, and have great application prospects in the biomedical field, such as cell sorting, protein purification, targeted drug delivery, magnetic resonance imaging contrast agents, tumor magnetic hyperthermia and the like, so that the research of the materials is highly regarded by the scientific community. The microscopic and surface structures of the superparamagnetic nano particles are regulated and controlled to adapt to the identification, control and capture of specific biomolecules so as to realize the detection of target biomolecules, and the superparamagnetic nano particles have huge application prospects in the aspects of early diagnosis of diseases and accurate medical treatment. As an information transmitter between the biosensor and the biomolecule, the concentration of the magnetic beads is not only one of the important parameters for characterizing the quantitative evaluation of the magnetic sorting efficiency, but particularly when the magnetic beads are used as magnetic labels, the concentration of the magnetic beads reflects the content of the labeled biomolecule. However, since the particle size of these magnetic beads exhibiting super paramagnetism is mostly in the nanometer or micrometer scale, not only the stray field of the magnetic beads is too small, but also there is mutual interference. Further, the method of realizing the residual magnetism detection of the magnetic beads by using the magnetic sensors such as the coil, the hall element, the giant magneto-impedance (GMI), the giant magneto-impedance (GMR) and the fluxgate, which are reported in the past, cannot realize the magnetic bead detection with high sensitivity and low detection limit. However, the use of sensors with ultra-high sensitivity and ultra-low detection limit, such as superconducting quantum interferometers or atomic magnetometers, greatly limits the convenience of detection, and thus accurate measurement of the concentration of magnetic beads is one of the important research directions in the field of magnetic labeled biomolecule detection.
The thickness-shearing quartz crystal oscillator is extremely sensitive to surface load, is often used as a high-sensitivity physical mass sensor called a Quartz Crystal Microbalance (QCM), and is widely and deeply applied to biochemical detection. The QCM measures the parameters of the load sample such as mass, viscosity, density and the like by utilizing the sensitivity of the thickness shear vibration quartz crystal to mechanical boundary conditions. However, whether the magnetic sensor or QCM is used to measure the magnetic beads in the solution directly, the magnetic beads in the measured solution are suspended or fixed on the adjacent surface of the sensor by non-rigid connection methods such as physical adsorption, chemical reaction or immune coupling, so as to improve the detection sensitivity. Therefore, the detection is very easily influenced by the Brownian motion of the magnetic beads to introduce background noise, and the detection limit of the sensor is difficult to reduce. Therefore, the establishment of a magnetic bead detection method with high sensitivity, strong stability and simple operation has great significance in the fields of biochemical analysis, molecular detection and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a system and a method for measuring the concentration of magnetic beads regulated and controlled by an alternating-current magnetic field.
The invention provides an alternating-current magnetic field regulated and controlled magnetic bead concentration measuring system which comprises a controllable alternating-current magnetic field source, a thickness shearing quartz crystal oscillator, an oscillation excitation source circuit and a signal processing unit, wherein:
a magnetic bead solution is loaded on a surface electrode of the thickness shearing quartz crystal oscillator;
the controllable alternating current magnetic field source provides an alternating current magnetic field applied to the magnetic bead solution; magnetizing the magnetic beads in the magnetic bead solution through an alternating-current magnetic field to enable the magnetic beads to generate magnetization spin motion;
the electrode of the thickness shearing quartz crystal oscillator is connected with the output end of the oscillation excitation source circuit, and the oscillation excitation source circuit excites the thickness shearing quartz crystal oscillator to vibrate and generate a vibration signal;
the thickness shearing quartz crystal oscillator detects magnetization spin motion generated by magnetic beads under the excitation of a magnetic field;
synthesizing vibration modulation signals by vibration of the quartz crystal and magnetic bead magnetization motion;
the signal processing unit analyzes the vibration modulation signal.
Preferably, the controllable alternating-current magnetic field source comprises an alternating-current source and a helmholtz coil, and the helmholtz coil is connected to the alternating-current source to provide an alternating-current magnetic field for the magnetic bead solution.
Preferably, the oscillation excitation source circuit comprises an oscillation excitation source, and an oscillation current source is connected to an electrode of the thickness shearing quartz crystal oscillator.
Preferably, the signal processing unit includes an amplifier module, an a/D converter, and a processor, wherein:
the amplifier module demodulates the vibration modulation signal to obtain a signal reflecting the magnetic bead magnetization motion information in the magnetic bead solution;
and converting the signal of the concentration of the reaction magnetic beads by the A/D converter, and then sending the signal into a processor for analysis to obtain the information of the concentration of the magnetic beads in the magnetic bead solution.
Preferably, the amplifier module comprises a lock-in amplifier or a pre-filter amplifier.
Preferably, the reference signal of the lock-in amplifier is a double frequency signal of the excitation frequency of the magnetic field.
Preferably, the alternating current magnetic field for exciting the magnetic beads to generate magnetization motion is horizontal or vertical to the surface of the thickness shear quartz crystal oscillator carrying the magnetic bead solution.
Preferably, the magnetic field for exciting the magnetic beads in the magnetic bead solution to generate magnetization motion is an alternating current magnetic field with a frequency lower than the oscillation frequency of the thickness-shear quartz crystal oscillator.
The measuring method of the magnetic bead concentration measuring system based on the alternating current magnetic field regulation comprises the following steps:
the method comprises the following initial steps: loading a magnetic bead solution on a surface electrode of the thickness shearing quartz crystal oscillator;
a loading step: the controllable alternating current magnetic field source provides an alternating current magnetic field applied to the magnetic bead solution; magnetizing magnetic beads in the magnetic bead solution through an alternating-current magnetic field to enable the magnetic beads to generate magnetization spin motion;
the oscillation excitation source circuit excites the thickness shear quartz crystal oscillator to vibrate and generate a vibration signal;
a modulation step: the vibration of the quartz crystal and the magnetization motion of the magnetic beads are synthesized into a vibration modulation signal;
and (3) analysis step: the signal processing unit analyzes the vibration modulation signal.
Compared with the prior art, the invention has the following beneficial effects:
1. the method can be used for measuring the concentration of the magnetic bead solution under various solution conditions, and has the characteristics of simplicity, rapidness and wide applicability.
2. The detection of the invention does not need to carry out drying or dewatering operation on the magnetic bead solution and does not need to fix the magnetic beads, thereby greatly simplifying the operation flow required by the magnetic bead detection, and greatly improving the detection speed while realizing high-sensitivity detection.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic diagram of a method and an apparatus for measuring a concentration of magnetic beads regulated by an ac magnetic field according to an embodiment of the present invention.
Fig. 2 is a measurement circuit diagram related to a method and an apparatus for measuring a concentration of magnetic beads regulated by an ac magnetic field according to an embodiment of the present invention.
Fig. 3 is a measurement circuit diagram related to another method and apparatus for measuring a concentration of magnetic beads by ac magnetic field regulation according to an embodiment of the present invention.
Fig. 4 is a frequency spectrum diagram of a detected modulation signal with a particle size of 0.28 μm and a concentration in a range from 100ng/ml to 1mg/ml according to the method and apparatus for measuring a magnetic bead concentration by ac magnetic field regulation and control provided by the embodiment of the present invention.
FIG. 5 is a time domain diagram of the AC magnetic field controlled magnetic bead concentration measurement method and apparatus provided in the embodiment of the present invention after demodulation for a concentration range of 100ng/ml to 1mg/ml, with a particle size of 0.28 μm.
FIG. 6 is a graph of the amplitude of a demodulated signal with a particle size of 0.28 μm and a concentration in a range of 10ng/ml to 10mg/ml using the method and apparatus for measuring the concentration of magnetic beads regulated by an AC magnetic field according to an embodiment of the present invention.
FIG. 7 is a graph showing the relationship between the concentration of a solution having a particle size of 0.28 μm and a concentration of 10-100ng/ml and the amplitude of the demodulated signal obtained by the method and the apparatus for measuring the concentration of magnetic beads controlled by an AC magnetic field according to the embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
As shown in fig. 1 to 7, the present invention provides a system and a method for measuring magnetic bead concentration by ac magnetic field regulation, wherein an external controllable ac magnetic field is used to excite magnetic beads to generate magnetization spin motion, a quartz crystal oscillator is used to detect the motion intensity of the magnetic beads, an ac magnetic field is applied to magnetize the magnetic beads suspended in a solution to generate magnetization spin, and the magnetic beads spin to generate friction with the solution; the friction force is transmitted to the surface of the quartz crystal through the solution and is subjected to motion synthesis with the vibration of the quartz crystal. The friction force disturbs the quartz crystal in oscillation, so that the motion signal of the magnetic beads is modulated on the oscillation signal of the quartz crystal to generate a synthetic vibration signal, and the magnetization spin motion signal of the magnetic beads can be extracted after the synthetic signal is decomposed. And the concentration of the magnetic beads in the solution is detected by analyzing the intensity of the magnetic bead magnetization motion signal after extraction. The amplitude of the modulation signal reflects the concentration of the magnetic beads in the solution loaded by the quartz crystal, because the movement intensity generated by the magnetization of the magnetic beads is influenced by the concentration of the magnetic beads. The method greatly inhibits the detection noise generated by the Brownian motion of the magnetic beads, and further can realize high-sensitivity detection.
The principle of the magnetic bead concentration measuring method regulated and controlled by the alternating-current magnetic field provided by the invention is as follows: because the magnetic beads have superparamagnetism, under an alternating-current excitation magnetic field, the magnetization response intensity of the magnetic beads follows a langevin function. Under the excitation of an alternating magnetic field, brownian relaxation of a magnetic bead can be regarded as simple harmonic motion in a solution, and the magnetic force on an easy magnetization axis of the magnetic bead is as follows:
where H is the applied magnetic field, B is the magnetic flux density of the particles, and v is the volume. When the particles are superparamagnetic, the magnetic flux density is
Wherein mu r The relative permeability of the magnetic beads. Therefore, the magnetic force acting on the superparamagnetic particles is largeIs small as
s is the area of the bead cross section perpendicular to the field, the direction of the magnetic force being parallel to the direction of the applied field. It is clear that the magnitude of the magnetic force is proportional to the square of the magnitude of the applied field. Thus the magnetic force F to which the magnetic beads are subjected m (t) can be expressed as:
wherein A is m Which represents the amplitude of the magnetic beads, which amplitude is positively correlated with the concentration of the magnetic beads in the liquid.
Showing the initial phase of the bead vibration. Due to the presence of even-order nonlinearities in the magnetization response, ω m An even multiple of the frequency of the excitation field. Similarly, according to the principle of inverse piezoelectric effect, the shearing force applied to the quartz crystal when electrically excited can be expressed as:
wherein A is q Which represents the amplitude of the quartz crystal,
showing the initial phase of the bead vibration. Because the magnetic particles contained in the liquid cover the surface of the quartz crystal electrode, the thickness shear oscillation state of the quartz crystal can be changed in the moving process, so that the impedance of the quartz crystal is changed. The resulting motion of the quartz crystal can be expressed as:
F s (t)＝F q (t)+F q (t)·F m (t), (6)
assuming that the initial phases are all 0, the equations (4) and (5) are substituted into (6) to obtain
F s (t)＝(A q +A m ·A q cosω m t)·cosω q t, (7)
Can see F s (t) amplitude of motion according to (A) q + m · q cos m t) change with frequency ω q Further, it can be obtained
The above formula shows the resultant movement F s (t) has a frequency ω in the frequency spectrum q ±ω m In short, the magnetic bead motion under the excitation of the external magnetic field is modulated onto the oscillation of the quartz crystal, so that we can evaluate the magnetic bead motion in the solution by detecting the sidebands in the oscillation signal of the quartz crystal representing the excitation of the magnetic bead.
The system for measuring the concentration of the magnetic beads regulated and controlled by the alternating-current magnetic field comprises a controllable alternating-current magnetic field source for generating magnetic bead magnetization motion, a quartz crystal oscillator for detecting the magnetic bead motion, an oscillating circuit for exciting the quartz crystal to vibrate and a signal processing unit for analyzing vibration signals. In the magnetic bead concentration measuring system regulated by the alternating-current magnetic field, the magnetic beads in the solution are magnetized by the alternating-current magnetic field to generate magnetization spin motion. The magnetization spin motion generated by the magnetic beads and the friction of the solution are transferred to and act on the surface of the quartz crystal contacted with the solution. The following is a more detailed description:
example 1
Fig. 1 is a schematic diagram of a magnetic bead concentration measurement system regulated by an ac magnetic field according to this embodiment. As shown in fig. 1, a method and an apparatus for measuring a concentration of magnetic beads by ac magnetic field regulation comprise a controllable ac magnetic field source 101, a quartz crystal 501, a quartz crystal surface electrode 401, a solution 201 to be measured loaded on the surface of the quartz crystal, an oscillation excitation source circuit 601, and a signal processing unit 301. The surface electrode 401 of the quartz crystal layer is connected to the output terminal of the oscillation excitation source circuit 601 to generate an oscillation signal determined by the characteristics of the quartz crystal oscillator, and the frequency of the oscillation signal is the excitation signal frequency. The thickness shearing quartz crystal oscillator detects the magnetization spin motion generated by the magnetic beads under the excitation of a magnetic field. The electrode surface of the quartz crystal oscillator is contacted with a magnetic bead solution sample; the output of the oscillation excitation source circuit enables the quartz crystal oscillator to generate vibration; magnetic beads are excited by a magnetic field to generate magnetization spin and rub with the solution; the friction force is transferred by taking the solution as a medium and acts on the quartz crystal, and the magnetization motion is modulated into the vibration of the quartz crystal oscillator. And demodulating a vibration modulation signal synthesized by the vibration of the quartz crystal and the magnetization motion of the magnetic beads by using a signal processing unit, and detecting the concentration of the magnetic beads by measuring the intensity of the magnetization motion signal of the magnetic beads. Wherein the magnetic field for exciting the magnetic beads in the solution to be detected to generate magnetization motion is an alternating current magnetic field with the frequency lower than the oscillation frequency of the quartz crystal oscillator. The magnetic field used for exciting the magnetic beads to generate magnetization motion needs to be horizontal or vertical to the surface of the quartz crystal loaded with the magnetic bead solution sample.
Fig. 2 shows the construction of the measuring device in this embodiment, and the controllable ac magnetic field source 101 is composed of an ac current source and a helmholtz coil to provide the ac magnetic field required for measurement. The quartz crystal 501 is placed in the center of the magnetic field and is voltage-excited by the oscillation excitation source circuit 601. The signal processing unit 301 in the embodiment is composed of a lock-in amplifier, an a/D and a processor, wherein the lock-in amplifier demodulates the modulation oscillation signal to obtain the signal of the concentration of the reaction magnetic beads, and the reference signal required for demodulation is the frequency doubling signal of the excitation magnetic field signal after passing through the frequency doubling circuit 801. And finally, the signal of the concentration of the reaction magnetic beads is sent into a processor after A/D conversion to be analyzed to obtain the magnetic bead magnetization motion information in the sample, so that the measurement of the concentration of the magnetic beads is realized.
In this example, the resonance frequency of the quartz wafer used was 5MHz, and the thickness of the quartz was 334 μm. And uniformly loading 80 mu L of the solution of the magnetic beads to be detected on the quartz crystal surface electrode 401 by using a liquid transfer meter, and applying an alternating current magnetic field horizontal to the quartz crystal 501 after the loading of the sample liquid to be detected is finished. The alternating current magnetic field is applied by adopting a controllable alternating current magnetic field source 101, the amplitude of the magnetic field is 150Oe, and the frequency is 70Hz.
Fig. 4 is a frequency spectrum diagram of a modulation signal detected by a method and an apparatus for measuring a concentration of magnetic beads regulated by an ac magnetic field according to an embodiment of the present invention, wherein the modulation signal has a particle size of 0.28 μm and a concentration of 100ng/ml to 1 mg/ml. Wherein the main peak of the signal in the frequency diagram represents the oscillation frequency of the quartz crystal, and the signal is generated by the oscillation excitation source circuit 601. Furthermore, the modulation signal is generated by the controllable alternating magnetic field source 101, and according to the principle described in the summary of the invention, the alternating magnetic field excites the magnetic beads in the solution to generate magnetization spin motion and transmit the magnetization spin motion to the surface of the quartz crystal through solution friction, so that the vibration of the quartz crystal and the friction synthesis of the magnetic beads are caused to generate the modulation signal. The sideband intensity of the modulation signal reflects the intensity of the magnetic bead movement in the solution. Further, as can be seen from fig. 4, the signal intensity demodulated by the lock-in amplifier increases with the increase of the concentration of the magnetic beads in the solution of the magnetic beads to be measured, and it is proved that the intensity of the side-band signal is positively correlated with the concentration of the magnetic beads.
FIG. 5 is a time domain diagram of the AC magnetic field controlled magnetic bead concentration measurement method and apparatus after demodulation with a particle size of 0.28 μm and a concentration in a range of 100ng/ml to 1 mg/ml. In this embodiment, the signal processing unit 301 is a lock-in amplifier, and the signal representing the intensity of the magnetic bead movement can be obtained by demodulating the modulated signal generated by the combination of the magnetic bead movement and the quartz crystal movement by the lock-in amplifier. Further, as can be seen from fig. 3, the signal indicating the intensity of the magnetic bead movement is a sinusoidal signal, and the intensity of the signal is related to the concentration of the magnetic bead in the solution to be measured.
Fig. 6 is a graph of demodulated signal amplitudes of the method and the device for measuring magnetic bead concentration by ac magnetic field regulation provided by the embodiment of the present invention for a concentration range of 10ng/ml to 10mg/ml, with a particle size of 0.28 μm. As can be seen from FIG. 6, the concentration of magnetic beads in the concentration range of 10ng/ml to 10mg/ml is proportional to the amplitude of the demodulated signal. It is stated that the higher the concentration of the magnetic beads in the solution to be measured, the greater the intensity of the magnetization motion of the magnetic beads under the excitation of the alternating-current magnetic field.
FIG. 7 is a diagram showing the relationship between the solution concentration and the demodulated signal amplitude in the range of 10ng/ml to 100ng/ml with the particle size of 0.28 μm and the concentration of the magnetic bead concentration regulated and controlled by the AC magnetic field according to the method and the device for measuring the magnetic bead concentration provided by the embodiment of the present invention. As can be seen from FIG. 7, the measured magnetization motion of the magnetic beads and the concentration of the magnetic beads show an approximately linear relationship in the range of 10ng/ml to 100ng/ml, which indicates that the magnetic bead detection method provided by the present invention has high sensitivity and resolution in the quantitative detection of low-concentration magnetic beads.
Example 2
Fig. 3 shows a construction diagram of another measuring apparatus, and a controllable ac magnetic field source 101 is composed of an ac current source and a helmholtz coil to provide an ac magnetic field required for measurement. The quartz crystal 501 is placed in the center of the magnetic field and is energized with a voltage supplied by an oscillation excitation source circuit 601. The signal processing unit 301 in the embodiment is composed of a pre-filter amplifier, an analog-to-digital (a/D) converter, and a processor, and the pre-filter amplifier can effectively improve the signal-to-noise ratio of the signal collected by the a/D converter to reduce quantization error. The voltage signal between two electrodes of the quartz crystal collected by the A/D converter is sent to the processor, and the collected modulation oscillation signal is digitally demodulated by the processor to obtain the signal of the concentration of the reaction magnetic bead, wherein the reference signal required by demodulation is a frequency doubling signal of the excitation magnetic field signal passing through the frequency doubling circuit 801.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (9)
1. The utility model provides a magnetic bead concentration measurement system of alternating current magnetic field regulation and control which characterized in that, includes controllable alternating current magnetic field source, thickness shear quartz crystal oscillator, vibration excitation source circuit and signal processing unit, wherein:
a magnetic bead solution is loaded on a surface electrode of the thickness shearing quartz crystal oscillator;
the controllable alternating current magnetic field source provides an alternating current magnetic field applied to the magnetic bead solution; magnetizing magnetic beads in the magnetic bead solution through an alternating-current magnetic field to enable the magnetic beads to generate magnetization spin motion;
the electrode of the thickness shearing quartz crystal oscillator is connected with the output end of the oscillation excitation source circuit, and the oscillation excitation source circuit excites the thickness shearing quartz crystal oscillator to vibrate and generate a vibration signal;
detecting magnetization spin motion generated by magnetic beads under the excitation of a magnetic field by a thickness shearing quartz crystal oscillator;
synthesizing vibration modulation signals by vibration of the quartz crystal and magnetic bead magnetization motion;
the signal processing unit analyzes the vibration modulation signal.
2. The system of claim 1, wherein the controllable ac magnetic field source comprises an ac current source and a helmholtz coil, and the helmholtz coil is connected to the ac current source to provide an ac magnetic field for the bead solution.
3. An AC magnetic field regulated bead concentration measurement system according to claim 1, wherein said oscillation excitation source circuit comprises an oscillation excitation source, and an oscillation current source is connected to an electrode of said thickness-shear quartz crystal oscillator.
4. The AC magnetic field regulated magnetic bead concentration measurement system of claim 1, wherein said signal processing unit comprises an amplifier module, an A/D converter, and a processor, wherein:
the amplifier module demodulates the vibration modulation signal to obtain a signal reflecting the magnetization motion information of the magnetic beads in the magnetic bead solution;
and converting the signal of the concentration of the reaction magnetic beads by the A/D converter, and then sending the signal into a processor for analysis to obtain the information of the concentration of the magnetic beads in the magnetic bead solution.
5. An AC magnetic field regulated bead concentration measurement system according to claim 4, wherein said amplifier module comprises a lock-in amplifier or a pre-filter amplifier.
6. The AC magnetic field regulated bead concentration measurement system according to claim 5, wherein the reference signal of said lock-in amplifier is a double frequency signal of the magnetic field excitation frequency.
7. The AC magnetic field controlled magnetic bead concentration measuring system according to claim 1, wherein the AC magnetic field for exciting the magnetic beads to generate magnetization motion is horizontal or vertical to the surface of the thickness-shear quartz crystal oscillator carrying the magnetic bead solution.
8. The system for measuring the concentration of magnetic beads regulated by the alternating-current magnetic field according to claim 1, wherein the magnetic field for exciting the magnetic beads in the magnetic bead solution to generate magnetization motion is an alternating-current magnetic field with a frequency lower than the oscillation frequency of a thickness-shear quartz crystal oscillator.
9. A measuring method of the alternating current magnetic bead concentration measuring system based on any one of claims 1 to 8, characterized by comprising the following steps:
the method comprises the following initial steps: loading a magnetic bead solution on a surface electrode of the thickness shearing quartz crystal oscillator;
a loading step: the controllable alternating current magnetic field source provides an alternating current magnetic field applied to the magnetic bead solution; magnetizing magnetic beads in the magnetic bead solution through an alternating-current magnetic field to enable the magnetic beads to generate magnetization spin motion;
the oscillation excitation source circuit excites the thickness shearing quartz crystal oscillator to vibrate and generate a vibration signal;
a modulation step: synthesizing vibration modulation signals by vibration of the quartz crystal and magnetic bead magnetization motion;
and (3) analysis step: the signal processing unit analyzes the vibration modulation signal.
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