Piezoelectric sensing module based on immunoaffinity reaction and application

Abstract

The invention discloses a piezoelectric sensing module based on immunoaffinity reaction and application, and belongs to the technical field of piezoelectric sensors. According to the specific scheme, the piezoelectric sensing module based on the immunoaffinity reaction comprises a piezoelectric sensor, an external magnetic field generation source and a plurality of immunomagnetic beads combined with a target object, a flow channel is formed in the upper surface of the piezoelectric sensor, and the immunomagnetic beads combined with the target object are located in the flow channel; the external magnetic field generation source is located at the bottom of the piezoelectric sensor, and the direction of the magnetic field force acting on the immunomagnetic beads points to the surface of the piezoelectric sensor. The immunomagnetic beads combined with the target object are controlled by an external magnetic field to be in contact with the surface of the piezoelectric sensor, the piezoelectric sensor is used for measuring the total mass of the immunomagnetic beads combined with the target object, and the concentration of the target object is obtained through analysis; after the measurement is completed, the external magnetic field is removed, and the immunomagnetic beads which are contacted with the upper surface of the piezoelectric sensor and are combined with the target object are removed by liquid scouring, so that the reuse of the sensor is realized, and the use cost of the device is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of piezoelectric sensors, and in particular relates to a piezoelectric sensing module based on immunoaffinity reaction and its application. Background Art

[0002] Piezoelectric sensors are devices that convert received acoustic signals into electrical signals through the piezoelectric effect. Piezoelectric sensors can characterize a variety of physical quantities such as temperature, stress, and mass. The principle is that when sound waves pass through the target medium, changes in the medium will affect the sound wave characteristics such as sound velocity and sound intensity. By measuring the changes in acoustic characteristics, the physical quantities that affect sound propagation can be indirectly characterized. With the advancement of micro-nano processing technology and the increasing perfection of piezoelectric material preparation technology, piezoelectric sensors based on piezoelectric resonators have significant advantages in miniaturization and integration, and are widely used in the fields of medical health and biological sciences. Piezoelectric resonators used in the field of sensing are mainly surface acoustic wave resonators and bulk acoustic wave resonators. Surface acoustic wave resonators usually select piezoelectric single crystal substrates such as lithium niobate, lithium tantalate, and bismuth germanate, and use interdigital electrodes to excite sound waves on the surface of the piezoelectric single crystal substrate. Bulk acoustic wave resonators usually select piezoelectric films such as aluminum nitride, and use top and bottom electrodes to excite sound waves in the piezoelectric film.

[0003] Immunoaffinity reaction is the reaction process of specific binding between antigen and antibody. Antigen and antibody with strong affinity can react quickly at low concentrations. This property makes it the basis of many biological experiments and clinical tests. Immunomarkers can bind to the target through immunoaffinity reaction. Immunomarkers can be fixed on the surface of the substrate or on the surface of microbeads. They are free in the liquid with the microbeads. Such microbeads are called immunobeads. Immunobeads with magnetic particles as the core are called immunomagnetic beads, which can be manipulated by external magnetic fields.

[0004] Traditional piezoelectric sensors based on immunoaffinity reactions fix immune markers on the surface of the piezoelectric substrate. The mass loading effect caused by the capture of the target by the immune marker will affect the resonant frequency of the sound wave, and the offset of the resonant frequency is used to characterize the total mass of the target. The disadvantages of the above sensors are that there is a saturation effect in the capture of the target, the sensors are difficult to reuse, the manufacturing and use costs are high, and they cannot be widely promoted in hospitals and clinics. Therefore, a new piezoelectric sensing module with reusable sensors is needed. Summary of the invention

[0005] In order to solve the technical problem that piezoelectric sensors based on immunoaffinity reactions in the prior art are not reusable, the present invention provides a piezoelectric sensing module based on immunoaffinity reactions and applications.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A piezoelectric sensing module based on immunoaffinity reaction comprises a piezoelectric sensor, an external magnetic field generating source and a plurality of immunomagnetic beads binding to a target object, wherein a flow channel is arranged on the upper surface of the piezoelectric sensor, and the plurality of immunomagnetic beads binding to the target object flow into the flow channel along with the liquid; the external magnetic field generating source is located at the bottom of the piezoelectric sensor, and the direction of the magnetic field force acting on the immunomagnetic beads binding to the target object points to the surface of the piezoelectric sensor.

[0008] Furthermore, the piezoelectric sensor includes a surface acoustic wave resonator or a bulk acoustic wave resonator.

[0009] Preferably, the surface acoustic wave resonator comprises interdigital electrodes and a piezoelectric substrate, and the interdigital electrodes are arranged on the surface of the piezoelectric substrate.

[0010] Furthermore, if there are two groups of interdigital electrodes, the projection of the flow channel on the upper surface of the piezoelectric substrate is between the two groups of interdigital electrodes; if there is one group of interdigital electrodes, the projection of the flow channel on the upper surface of the piezoelectric substrate overlaps with the interdigital electrodes.

[0011] Preferably, the BAW resonator comprises a top electrode, a piezoelectric film, a bottom electrode, an acoustic reflection layer and a substrate stacked in sequence from top to bottom, and the flow channel is arranged on the upper surface of the top electrode.

[0012] Furthermore, the piezoelectric film is composed of more than one layer of piezoelectric material, and the piezoelectric material includes any one or more combinations of aluminum nitride, scandium-doped aluminum nitride, lithium niobate, lithium tantalate and lead zirconate titanate.

[0013] Furthermore, the external magnetic field source includes a permanent magnet, an electromagnet or a combination of the two.

[0014] Furthermore, the immunomagnetic beads binding to the target include the target and the immunomagnetic beads, the immune markers on the immunomagnetic beads bind to the target through immune affinity reaction, and the diameter of the circumscribed sphere of the immunomagnetic beads is greater than 10 nm and smaller than the diameter of the circumscribed sphere of the target.

[0015] Furthermore, the thickness of the top electrode is between 10-1000 nm, the thickness of the bottom electrode is between 10-1000 nm, and the thickness of the piezoelectric film is between 100-5000 nm.

[0016] An application of the piezoelectric sensing module based on immunoaffinity reaction comprises the following steps:

[0017] Step 1: The immunomagnetic beads bound to the target object flow into the flow channel above the piezoelectric sensor along with the liquid;

[0018] Step 2: an external magnetic field source applies an external magnetic field to manipulate the immunomagnetic beads that bind to the target object to contact the upper surface of the piezoelectric sensor;

[0019] Step 3: Use a piezoelectric sensor to measure the total mass of the immunomagnetic beads bound to the target, and analyze and obtain the concentration of the target;

[0020] Step 4: Remove the external magnetic field and use the liquid in the flow channel to flush away the immunomagnetic beads bound to the target object on the surface of the piezoelectric sensor.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Compared with traditional piezoelectric sensors based on immune affinity reactions, the present invention does not need to fix immune markers on the surface of the piezoelectric sensor, but only uses immune magnetic beads as immune marker carriers. The immune magnetic beads bound to the target are manipulated by an external magnetic field to make them contact the surface of the piezoelectric sensor, and then the total mass of the immune magnetic beads bound to the target is measured by the piezoelectric sensor to analyze and obtain the concentration of the target. After the measurement is completed, the external magnetic field is removed, and the immune magnetic beads bound to the target on the surface of the piezoelectric sensor are removed by liquid flushing, thereby realizing the reuse of the sensor and reducing the cost of device use.

[0023] The mass of the target increases after combining with the immunomagnetic beads, and the mass loading effect caused when it contacts the surface of the piezoelectric sensor becomes more significant, the offset of the resonant frequency increases, and the sensitivity of the piezoelectric sensor module improves.

[0024] When there are other impurities in the flow channel besides the target object and the immunomagnetic beads, the present invention can simultaneously achieve separation of the target object from the impurities and sensing of the target object quality.

[0025] The external magnetic field generator can flexibly adjust the strength of the external magnetic field, making the piezoelectric sensor module suitable for a variety of application scenarios with different target sizes.

[0026] The piezoelectric sensing module described in the present invention can be integrated with other conventional microfluidic modules, such as an acoustophoresis module and an acoustofluidic mixing module, to form a microfluidic system-on-chip, thereby realizing system integration and miniaturization, reducing the manufacturing cost of the system, and effectively reducing the loss caused by the transfer of the target object between different modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a cross-sectional schematic diagram of the structure of a piezoelectric sensing module based on immunoaffinity reaction, where A is the direction of the magnetic field force;

[0028] Figure 2 Schematic diagrams of the top view (a) and bottom view (b) of a piezoelectric sensing module structure based on a surface acoustic wave resonator including two groups of interdigitated electrodes;

[0029] Figure 3 is a cross-sectional schematic diagram of a piezoelectric sensing module structure based on a surface acoustic wave resonator including a group of interdigitated electrodes;

[0030] Figure 4 is a cross-sectional schematic diagram of the structure of a piezoelectric sensing module based on a bulk acoustic wave resonator;

[0031] In the figure, 1. piezoelectric sensor, 2. external magnetic field source, 3. immunomagnetic beads bound to the target, 4. flow channel, 11. surface acoustic wave resonator, 12. bulk acoustic wave resonator, 111. interdigitated electrodes, 112. piezoelectric substrate, 121. top electrode, 122. piezoelectric film, 123. bottom electrode, 124. acoustic reflection layer, 125. substrate. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Specific implementation method 1

[0034] A piezoelectric sensing module based on immunoaffinity reaction includes a piezoelectric sensor 1, an external magnetic field source 2 and a plurality of immunomagnetic beads 3 for binding to a target object. A flow channel 4 is provided on the upper surface of the piezoelectric sensor 1, and a plurality of immunomagnetic beads 3 for binding to a target object flow into the flow channel 4 along with a liquid. The external magnetic field source 2 is located at the bottom of the piezoelectric sensor 1, and the direction of the magnetic field force acting on the immunomagnetic beads 3 for binding to a target object points to the surface of the piezoelectric sensor 1, so that the immunomagnetic beads 3 for binding to a target object can be manipulated to contact the surface of the piezoelectric sensor 1. The structural schematic diagram is shown in FIG. Figure 1 shown.

[0035] Furthermore, the immunomagnetic beads 3 binding to the target include the target and the immunomagnetic beads, and the immune markers on the immunomagnetic beads bind to the target by immunoaffinity reaction. The diameter of the circumscribed sphere of the immunomagnetic beads is greater than 10 nm and smaller than the diameter of the circumscribed sphere of the target.

[0036] Furthermore, the piezoelectric sensor 1 is a surface acoustic wave resonator 11 .

[0037] Furthermore, the surface acoustic wave resonator 11 includes interdigital electrodes 111 and a piezoelectric substrate 112, wherein the interdigital electrodes 111 are arranged on the surface of the piezoelectric substrate 112. The piezoelectric substrate 112 is a piezoelectric single crystal substrate; the interdigital electrodes 111 are in two groups, and the projection of the flow channel 4 on the upper surface of the piezoelectric substrate 112 is between the two groups of interdigital electrodes 111, such as Figure 2As shown in (a) and (b). When the piezoelectric sensor is working, the electrical signal is input into the left interdigital electrode, and the left interdigital electrode generates a sound wave propagating to the right through the piezoelectric effect. The right interdigital electrode receives the sound wave propagated through the flow channel 4, converts it into an electrical signal and outputs it. By analyzing the admittance curve of the output electrical signal, the total mass of the immunomagnetic beads 3 bound to the target is measured.

[0038] Furthermore, the external magnetic field source 2 includes a permanent magnet, an electromagnet or a combination of the two.

[0039] Furthermore, the material of the interdigitated electrodes 11 includes any one or more of the following conductive elements: gold, aluminum, copper, titanium, palladium, chromium, molybdenum and platinum.

[0040] Furthermore, the thickness of the interdigital electrodes is between 40-3000 nm.

[0041] The workflow includes the following steps:

[0042] Step 1: The immunomagnetic beads 3 bound to the target object flow into the flow channel 4 above the piezoelectric sensor 1 along with the liquid;

[0043] Step 2: The external magnetic field source 2 applies an external magnetic field to manipulate the immunomagnetic beads 3 that bind to the target object to contact the upper surface of the piezoelectric sensor 1;

[0044] Step 3: Use the piezoelectric sensor 1 to measure the total mass of the immunomagnetic beads 3 bound to the target, and analyze and obtain the concentration of the target;

[0045] Step 4: Remove the external magnetic field and use the liquid in the flow channel 4 to flush away the immunomagnetic beads 3 bound to the target object on the upper surface of the piezoelectric sensor 1 .

[0046] After completing step 4, step 1 can be performed, thereby realizing the reuse of the piezoelectric sensor 1.

[0047] The method of removing the external magnetic field includes: moving the external magnetic field source 2 away from the flow channel 4 and the piezoelectric sensor 1; when the external magnetic field source 2 is an electromagnet, turning off the power supply of the electromagnet.

[0048] This specific embodiment shows that the admittance curve is obtained based on the surface acoustic wave resonator parameters, and the expression of the piezoelectric equation for obtaining the admittance curve is:

[0049] T=cS-eE

[0050] D=εE-eS

[0051] Among them, T is the stress matrix, c is the stiffness matrix of the piezoelectric material, S is the strain matrix, e is the piezoelectric stress matrix, E is the electrostatic field intensity, D is the electric displacement, and ε is the dielectric matrix of the piezoelectric material. The resonant frequency and electromechanical coupling coefficient of the surface acoustic wave resonator are adjusted according to the piezoelectric stress matrix e. The piezoelectric stress matrix is:

[0052]

[0053] Among them, e15, e22, e24, e31, and e33 are piezoelectric coefficients of the piezoelectric materials in corresponding directions respectively; based on the above equation, the theoretical admittance curve of the surface acoustic wave resonator is determined by finite element simulation method and the geometric parameters are adjusted; the surface acoustic wave resonator is manufactured, and the actual admittance curve of the surface acoustic wave resonator is obtained by testing, and the geometric dimensions and process parameters are further adjusted according to the actual admittance curve, and finally the geometric dimensions and process parameters of the surface acoustic wave resonator that meets the requirements are determined. Specific implementation method 2

[0055] The difference from the first embodiment is that the number and arrangement of the interdigital electrodes 111 are different. This embodiment includes a group of interdigital electrodes, and the projection of the flow channel 4 on the upper surface of the piezoelectric substrate 112 overlaps with the interdigital electrodes 111. Figure 3 When the piezoelectric sensor is working, the electric signal is input into the interdigital electrodes, and the mass load effect caused by the contact between the immunomagnetic beads 3 bound to the target and the interdigital electrodes 111 will affect the admittance curve of the electric signal. The total mass of the immunomagnetic beads 3 bound to the target can be measured by analyzing the change in the admittance curve. The rest is the same as the first embodiment. Specific implementation method three

[0057] A piezoelectric sensing module based on immunoaffinity reaction includes a piezoelectric sensor 1, an external magnetic field source 2 and a plurality of immunomagnetic beads 3 that bind to a target object. A flow channel 4 is provided on the surface of the piezoelectric sensor 1, and the plurality of immunomagnetic beads 3 that bind to a target object flow into the flow channel 4 along with the liquid. The external magnetic field source 2 is located at the bottom of the piezoelectric sensor 1, and the direction of the magnetic field force acting on the immunomagnetic beads 3 points to the surface of the piezoelectric sensor 1.

[0058] Furthermore, the immunomagnetic beads 3 for binding to the target include the target and the immunomagnetic beads, and the immune markers on the immunomagnetic beads bind to the target by immunoaffinity reaction. The diameter of the circumscribed sphere of the immunomagnetic beads is greater than 10 nm and smaller than the diameter of the circumscribed sphere of the target.

[0059] Furthermore, the piezoelectric sensor 1 is a bulk acoustic wave resonator 12 .

[0060] Furthermore, the BAW resonator 12 includes a top electrode 121, a piezoelectric film 122, a bottom electrode 123, an acoustic reflection layer 124 and a substrate 125 stacked in sequence from top to bottom, and the flow channel 4 is arranged on the upper surface of the top electrode 121. Figure 4 shown.

[0061] Furthermore, the piezoelectric film 122 is composed of one or more layers of piezoelectric material, and the piezoelectric material includes any one or more combinations of aluminum nitride, scandium-doped aluminum nitride, lithium niobate, lithium tantalate, and lead zirconate titanate.

[0062] Furthermore, the external magnetic field source 2 includes a permanent magnet, an electromagnet or a combination of the two.

[0063] Furthermore, the thickness of the top electrode 121 is between 10-1000 nm, the thickness of the bottom electrode 123 is between 10-1000 nm, and the thickness of the piezoelectric film 122 is between 100-5000 nm.

[0064] Furthermore, the top electrode material includes any one or more of the following conductive elements: gold, aluminum, copper, titanium, palladium, chromium, molybdenum and platinum.

[0065] The bottom electrode material includes any one or more of the following conductive elements: gold, aluminum, copper, titanium, palladium, chromium, molybdenum and platinum.

[0066] The acoustic reflection layer is a Bragg reflection layer. The Bragg reflection layer is formed by alternately stacking multiple layers of materials with different acoustic impedances. This design enables the incident sound waves within a specific frequency range to be efficiently reflected, thereby reducing the leakage of sound energy and improving the quality factor of the bulk acoustic wave resonator.

[0067] The substrate material is silicon or silicon carbide.

[0068] The workflow includes the following steps:

[0069] Step 1: The immunomagnetic beads 3 bound to the target object flow into the flow channel 4 above the piezoelectric sensor 1 along with the liquid;

[0070] Step 2: The external magnetic field source 2 applies an external magnetic field to manipulate the immunomagnetic beads 3 that bind to the target object to contact the upper surface of the piezoelectric sensor 1;

[0071] Step 3: Use the piezoelectric sensor 1 to measure the total mass of the immunomagnetic beads 3 bound to the target, and analyze and obtain the concentration of the target;

[0072] Step 4: Remove the external magnetic field and use the liquid in the flow channel 4 to flush away the immunomagnetic beads 3 bound to the target object on the upper surface of the piezoelectric sensor 1 .

[0073] After completing step 4, step 1 can be performed, thereby realizing the reuse of the piezoelectric sensor 1.

[0074] The method of removing the external magnetic field includes: moving the external magnetic field source 2 away from the flow channel 4 and the piezoelectric sensor 1; when the external magnetic field source 2 is an electromagnet, turning off the power supply of the electromagnet.

[0075] When the piezoelectric sensor is working, the electrical signal is input into the top electrode 121 and the bottom electrode 123. The mass loading effect caused by the contact between the immunomagnetic beads 3 bound to the target and the top electrode 121 will affect the admittance curve of the electrical signal. The change in the admittance curve can be analyzed to measure the total mass of the immunomagnetic beads 3 bound to the target.

[0076] This specific embodiment shows that the admittance curve is obtained based on the bulk acoustic wave resonator parameters, and the expression of the piezoelectric equation for obtaining the admittance curve is:

[0077] T=cS-eE

[0078] D=εE-eS

[0079] Among them, T is the stress matrix, c is the stiffness matrix of the piezoelectric material, S is the strain matrix, e is the piezoelectric stress matrix, E is the electrostatic field intensity, D is the electric displacement, and ε is the dielectric matrix of the piezoelectric material. The resonant frequency and electromechanical coupling coefficient of the BAW resonator are adjusted according to the piezoelectric stress matrix e. The piezoelectric stress matrix is:

[0080]

[0081] Among them, e15, e22, e24, e31, and e33 are piezoelectric coefficients in corresponding directions of piezoelectric materials respectively; based on the above equation, the theoretical admittance curve of the BAW resonator is determined by finite element simulation method and the geometric parameters are adjusted; the BAW resonator is manufactured, and the actual admittance curve of the BAW resonator is obtained by testing, and the geometric dimensions and process parameters are further adjusted according to the actual admittance curve, and finally the geometric dimensions and process parameters of the BAW resonator that meet the requirements are determined.

[0082] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A piezoelectric sensing module based on immunoaffinity reaction, characterized in that: The invention comprises a piezoelectric sensor (1), an external magnetic field source (2) and a plurality of immunomagnetic beads (3) for binding to a target object; a flow channel (4) is arranged on the upper surface of the piezoelectric sensor (1); the plurality of immunomagnetic beads (3) for binding to a target object flow into the flow channel (4) along with liquid; the external magnetic field source (2) is located at the bottom of the piezoelectric sensor (1), and the direction of the magnetic field force acting on the immunomagnetic beads (3) for binding to a target object points to the surface of the piezoelectric sensor (1).

2. The piezoelectric sensing module based on immunoaffinity reaction according to claim 1, characterized in that: The piezoelectric sensor (1) comprises a surface acoustic wave resonator (11) or a bulk acoustic wave resonator (12).

3. The piezoelectric sensing module based on immunoaffinity reaction according to claim 2, characterized in that: The surface acoustic wave resonator (11) comprises interdigital electrodes (111) and a piezoelectric substrate (112), wherein the interdigital electrodes (111) are arranged on the surface of the piezoelectric substrate (112).

4. The piezoelectric sensing module based on immunoaffinity reaction according to claim 3, characterized in that: If the interdigital electrodes (111) are in two groups, the projection of the flow channel (4) on the upper surface of the piezoelectric substrate (112) is between the two groups of interdigital electrodes (111); if the interdigital electrodes (111) are in one group, the projection of the flow channel (4) on the upper surface of the piezoelectric substrate (112) overlaps with the interdigital electrodes (111).

5. The piezoelectric sensing module based on immunoaffinity reaction according to claim 2, characterized in that: The bulk acoustic wave resonator (12) comprises a top electrode (121), a piezoelectric film (122), a bottom electrode (123), an acoustic reflection layer (124) and a substrate (125) which are stacked in sequence from top to bottom, and the flow channel (4) is arranged on the upper surface of the top electrode (121).

6. The piezoelectric sensing module based on immunoaffinity reaction according to claim 5, characterized in that: The piezoelectric film (122) is composed of one or more layers of piezoelectric material, and the piezoelectric material includes any one or more combinations of aluminum nitride, scandium-doped aluminum nitride, lithium niobate, lithium tantalate and lead zirconate titanate.

7. The piezoelectric sensing module based on immunoaffinity reaction according to claim 1, characterized in that: The external magnetic field generating source (2) comprises a permanent magnet, an electromagnet or a combination of the two.

8. The piezoelectric sensing module based on immunoaffinity reaction according to claim 1, characterized in that: The immunomagnetic beads (3) for binding to the target include the target and the immunomagnetic beads. The immune markers on the immunomagnetic beads bind to the target through immunoaffinity reaction. The diameter of the circumscribed sphere of the immunomagnetic beads is greater than 10 nm and smaller than the diameter of the circumscribed sphere of the target.

9. The piezoelectric sensing module based on immunoaffinity reaction according to claim 5, characterized in that: The thickness of the top electrode (121) is between 10 and 1000 nm, the thickness of the bottom electrode (123) is between 10 and 1000 nm, and the thickness of the piezoelectric film (122) is between 100 and 5000 nm.

10. An application of a piezoelectric sensing module based on immunoaffinity reaction according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: The immunomagnetic beads (3) bound to the target object flow into the flow channel (4) above the piezoelectric sensor (1) along with the liquid; Step 2: an external magnetic field source (2) applies an external magnetic field to manipulate the immunomagnetic beads (3) binding to the target object to contact the upper surface of the piezoelectric sensor (1); Step 3: Using the piezoelectric sensor (1) to measure the total mass of the immunomagnetic beads (3) bound to the target, and analyzing to obtain the concentration of the target; Step 4: Remove the external magnetic field and use the liquid in the flow channel (4) to flush away the immunomagnetic beads (3) bound to the target object that are in contact with the upper surface of the piezoelectric sensor (1).

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