Lamb wave acoustic devices, sensors, microparticle manipulation devices and methods of manipulation

Abstract

The application discloses a Lamb wave acoustic device, a sensor, a micro-particle manipulation device and a manipulation method. The Lamb wave acoustic device comprises an ultrasonic excitation assembly and an ultrasonic transduction assembly. The ultrasonic transduction assembly comprises an excitation piece and a first excitation electrode group. The excitation piece is provided with opposite first excitation areas and second excitation areas. The first excitation electrode group comprises a first electrode and a second electrode. At least the first electrode is an array electrode. The array electrode comprises a plurality of strip electrodes arranged at intervals along a first direction. The first electrode and the second electrode are electrically connected with the ultrasonic excitation assembly. The ultrasonic transduction assembly has a first resonance frequency and / or a second resonance frequency. When the frequency of an excitation electric signal is equal to the first resonance frequency, the excitation piece generates a Lamb wave field. When the frequency of the excitation electric signal is equal to the second resonance frequency, the excitation piece generates a periodic resonance wave field. The Lamb wave acoustic device can easily generate a Lamb wave field or a periodic resonance wave field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of acoustic devices, in particular to a Lamb wave acoustic device, a sensor, a particle manipulation device and a manipulation method. BACKGROUND

[0002] When sound waves propagate in a plate-like medium, the wave pattern is called a plate (Lamb) wave. Lamb waves can propagate in a plate with a thickness comparable to the wavelength of the sound wave, forming an acoustic field throughout the thickness of the plate. During the propagation of Lamb waves, on the two surfaces of the solid, the particles vibrate along an elliptical trajectory, the same as Rayleigh waves; in the interior of the plate, the particle vibration is different due to the wave pattern, when the wave pattern is symmetric, the trajectory of the particle vibration is the same as the longitudinal wave; when the wave pattern is asymmetric, it is similar to the transverse wave. Plate waves can propagate in a plate with free boundaries, and there are plate waves on the upper and lower surfaces and the interior of the plate.

[0003] Among them, the zero-order asymmetric (A0) mode Lamb wave mode acoustic field is localized on the surface of the plate, attenuates along the vertical direction of the plate surface, is a high-gradient localized mode acoustic field, and this acoustic field can enhance the interaction between the wave and the matter, and improve the sensing, particle manipulation and other capabilities. However, A0 mode Lamb waves are generally difficult to excite. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a Lamb wave acoustic device, which can easily excite a Lamb wave field or a periodic resonance wave field.

[0005] The present application also proposes a sensor comprising a Lamb wave acoustic device.

[0006] The present application also proposes a particle manipulation device comprising a Lamb wave acoustic device.

[0007] The present application also proposes a particle manipulation method.

[0008] The Lamb wave acoustic device according to the first aspect of the present application comprises:

[0009] An ultrasonic excitation assembly for emitting an excitation electrical signal;

[0010] An ultrasonic transducer assembly includes an exciter and a first excitation electrode group. The exciter has a first excitation region and a second excitation region respectively disposed on both sides. The first excitation electrode group includes a first electrode disposed in the first excitation region and a second electrode disposed in the second excitation region. At least the first electrode is an array electrode, which includes a plurality of strip electrodes spaced apart along a first direction. The first electrode and the second electrode are electrically connected to the ultrasonic excitation assembly to convert the excitation electrical signal into a mechanical vibration signal.

[0011] Wherein, the ultrasonic transducer has a first resonant frequency, and when the frequency of the excitation electrical signal is equal to the first resonant frequency, the exciter generates a Lamb wave field; and / or, the ultrasonic transducer has a second resonant frequency, and when the frequency of the excitation electrical signal is equal to the second resonant frequency, the exciter generates the periodic resonant wave field.

[0012] The Lamb wave acoustic device according to embodiments of the present invention has at least the following beneficial effects:

[0013] This Lamb wave acoustic device integrates an artificial structure and an ultrasonic transducer to excite Lamb wave fields or periodic resonant wave fields. Furthermore, its simple structure, small size, and compatibility with other components make it suitable for various microfluidic sensors or particle manipulation devices. For example, when applied to sensors, the Lamb wave acoustic device is particularly sensitive to liquid mixtures with significant changes in density and sound velocity, making it applicable to various microfluidic sensing scenarios. When applied to particle manipulation devices, by exciting two different sound fields, it enables various forms of particle manipulation, such as trapping, suspending, and translating, improving particle manipulation accuracy, reducing energy consumption, and making the device more compact and miniaturized. Moreover, this particle manipulation device has relatively low frequency requirements for the excitation electrical signal, making the excitation of manipulation modes easier.

[0014] According to some embodiments of the present invention, the excitation element is configured as a piezoelectric plate made of piezoelectric material, and the first excitation region and the second excitation region are disposed on opposite side plates of the piezoelectric plate.

[0015] According to some embodiments of the present invention, the exciter includes a main body and a piezoelectric film covering both sides of the main body, wherein the first excitation region and the second excitation region are disposed on the side of the piezoelectric film away from the main body, and wherein the main body is made of a non-piezoelectric material.

[0016] According to some embodiments of the present invention, the first electrode is the array electrode, the second electrode is a full-coverage electrode that completely covers the second excitation region, and the ultrasonic transducer has a first resonant frequency that enables the exciter to generate the Lamb wave field and a second resonant frequency that enables the exciter to generate the periodic resonant wave field.

[0017] According to some embodiments of the present invention, both the first electrode and the second electrode are array electrodes, and the strip electrodes of the first electrode and the strip electrodes of the second electrode are alternately arranged, and the ultrasonic transducer has a first resonant frequency that enables the exciter to generate a Lamb wave field.

[0018] According to some embodiments of the present invention, both the first electrode and the second electrode are array electrodes, and the strip electrodes of the first electrode and the strip electrodes of the second electrode are disposed opposite to each other, and the ultrasonic transducer has a second resonant frequency that enables the exciter to generate a periodic resonant wave field.

[0019] According to some embodiments of the present invention, the spacing T between adjacent strip electrodes has the following relationship with the thickness H of the excitation element: H / T≤0.35.

[0020] According to a second aspect of the present invention, a sensor includes a Lamb wave acoustic device as described in any of the foregoing embodiments, the sensor being used to detect changes in the physical parameters of a sample to be tested.

[0021] In some embodiments, the first resonant frequency decreases in response to an increase in the density of the sample under test; and / or, the second resonant frequency increases in response to an increase in the sound velocity in the sample under test.

[0022] The particle manipulation method according to a third aspect of the present invention includes a Lamb wave acoustic device as described in any of the above embodiments.

[0023] In some embodiments, when the frequency of the excitation electrical signal is equal to the first resonant frequency, the exciter is excited to generate a Lamb wave field to drive the particle toward the surface of the exciter; and / or, when the frequency of the excitation electrical signal is equal to the second resonant frequency, the exciter is excited to generate a periodic resonant wave field to drive the particle to suspend on the surface of the exciter.

[0024] In some embodiments, the plate surface of the excitation element is further provided with a third excitation region spaced apart from the first excitation region and a fourth excitation region spaced apart from the second excitation region. The third excitation region and the fourth excitation region are arranged opposite to each other. The ultrasonic transducer assembly includes a second excitation electrode group, which includes a third electrode disposed in the third excitation region and a fourth electrode disposed in the fourth excitation region. The third electrode and the fourth electrode are respectively electrically connected to the ultrasonic excitation assembly to convert the excitation electrical signal into a mechanical vibration signal.

[0025] The third electrode is the same as the first electrode, and the fourth electrode is the same as the second electrode, so as to generate a standing wave field between the first excitation electrode group and the second excitation electrode group, and control the translation of the particle by changing the phase of the excitation electrical signal.

[0026] In some embodiments, the Lamb wave acoustic device further includes a container for storing an acoustic propagation medium containing the particles, the container being disposed in contact with the ultrasonic transducer assembly;

[0027] The Lamb wave acoustic device further includes a driving mechanism connected to the ultrasonic transducer assembly or the container. The driving mechanism is used to drive the ultrasonic transducer assembly and the container to move relative to each other, so as to adjust the position of the particles in the container.

[0028] The particle manipulation method according to a fourth aspect of the present invention includes the following steps:

[0029] S100. Simulation is performed using computer software to obtain optimized electrode parameter information and excitation element parameter information;

[0030] S200. Fabricate the excitation component based on the excitation component parameter information;

[0031] S300. Electrodes are coated on both sides of the excitation element according to the electrode parameter information to form an ultrasonic transducer assembly.

[0032] S400. The first resonance frequency and / or the second resonance frequency of the ultrasonic transducer are obtained by conducting a normalized resonance experiment on the ultrasonic transducer.

[0033] S500, the frequency of the excitation electrical signal of the ultrasonic excitation component is adjusted to the first resonant frequency to excite the ultrasonic transducer component to generate a Lamb wave field, so that the driving particles move toward the plate surface of the excitation element; or, the frequency of the excitation electrical signal of the ultrasonic excitation component is adjusted to the second resonant frequency to excite the ultrasonic transducer component to generate a periodic resonant wave field, so as to drive the particles to suspend on the plate surface of the excitation element.

[0034] According to some embodiments of the present invention, two identically spaced electrodes are coated on each side plate of the excitation element, and the step S500 is further comprising the following steps:

[0035] S600. Adjust the phase of the excitation electrical signal to control the translation of the particles.

[0036] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0038] Figure 1 This is a schematic diagram of the structure of the Lamb wave acoustic device according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram showing a strip electrode disposed in the first region of the excitation element according to an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of one embodiment of the present invention;

[0041] Figure 4 for Figure 3 Spectrum diagram and sound pressure field distribution diagram of the implementation method;

[0042] Figure 5 The acoustic pressure field distribution diagram and acoustic radiation force distribution diagram of the Lamb wave field and periodic resonant wave field are shown in the embodiments of the present invention.

[0043] Figure 6 This is a diagram showing the arrangement of particles in the Lamb wave field according to an embodiment of the present invention;

[0044] Figure 7 This is a diagram showing the arrangement of particles in a periodic resonant wave field according to an embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of another embodiment of the present invention;

[0046] Figure 9 for Figure 8 Spectrum diagram and sound pressure field distribution diagram of the implementation method;

[0047] Figure 10 This is a schematic diagram of another embodiment of the present invention;

[0048] Figure 11 for Figure 10Spectrum diagram and sound pressure field distribution diagram of the implementation method;

[0049] Figure 12 This is a schematic diagram of another embodiment of the excitation element in this invention;

[0050] Figure 13 This is a dispersion curve of the excitation element when the electrode spacing is 0.45 mm in an embodiment of the present invention;

[0051] Figure 14 This is a schematic diagram showing that a strip electrode is provided in the first excitation region and the third excitation region of the excitation element according to an embodiment of the present invention;

[0052] Figure 15 This is a schematic diagram illustrating the adjustment of phase to manipulate particle movement according to an embodiment of the present invention;

[0053] Figure 16 This is a schematic diagram of the Lamb wave acoustic device applied to a particle manipulation device according to an embodiment of the present invention;

[0054] Figure 17 This is a schematic diagram of the Lamb wave acoustic device applied to a sensor according to an embodiment of the present invention;

[0055] Figure 18 These are schematic diagrams of two sets of comparative tests of the sensor according to an embodiment of the present invention;

[0056] Figure 19 This is a schematic diagram illustrating the variation of the resonant frequency with the thickness of the excitation element and the electrode spacing in an embodiment of the present invention.

[0057] Figure 20 This is a flowchart of a particle manipulation method according to an embodiment of the present invention.

[0058] Figure label:

[0059] Ultrasonic excitation component 100;

[0060] Ultrasonic transducer 200; exciter 210; first excitation region 211; third excitation region 212; piezoelectric plate 213; main body 214; piezoelectric film 215; first electrode 220; second electrode 230; third electrode 240;

[0061] Container 300. Detailed Implementation

[0062] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0063] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0064] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0065] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0066] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Existing acoustic manipulation technologies mainly use surface waves or bulk waves to manipulate particles. Surface wave-based manipulation offers high precision, but the operating frequency of the manipulation device is relatively high, often requiring a sound wave frequency greater than 20MHz. This places high demands on the ultrasonic transducer, resulting in higher equipment manufacturing costs and greater energy consumption during operation. Bulk wave-based manipulation devices can control particles over a wider frequency range, but they require the use of artificial structures such as phonon crystals and metasurfaces to modulate the sound field. These additional artificial structures not only make the overall Lamb wave acoustic device larger but also increase the difficulty of debugging it, making the Lamb wave acoustic device complex and unstable.

[0068] like Figure 1As shown, an embodiment of the first aspect of this application proposes a Lamb wave acoustic device. By integrating an artificial structure and an ultrasonic transducer, it is possible to excite a Lamb wave field or a periodic resonant wave field. Furthermore, this acoustic device has a simple structure, small size, and is compatible with other components, making it applicable to various microfluidic sensors or particle manipulation devices. For example, when the Lamb wave acoustic device of the first aspect of this application is applied to a sensor of the second aspect of this application, it is particularly sensitive to liquid mixtures with significant changes in density and sound velocity, and can be used in various microfluidic sensing scenarios. When the Lamb wave acoustic device of the first aspect of this application is applied to a particle manipulation device of the third aspect of this application, by exciting two different sound fields, it is possible to achieve various forms of manipulation such as particle capture and arrangement, suspension arrangement, and translation, improving the accuracy of particle manipulation, reducing the energy consumption of particle manipulation, and making the particle manipulation device more compact and miniaturized. Moreover, this particle manipulation device has relatively low requirements for the frequency of the excitation electrical signal, making the excitation of manipulation modes easier.

[0069] Specifically, the Lamb wave acoustic device includes an ultrasonic excitation component 100 and an ultrasonic transducer component 200. The ultrasonic excitation component 100 includes a signal generator, a power amplifier, and an electronic control component. The signal generator generates an electrical signal, the power amplifier amplifies the electrical signal, and the electronic control component adjusts the parameters of the signal generator, power amplifier, etc., so that the ultrasonic excitation component 100 emits the required excitation electrical signal. The ultrasonic transducer component 200 converts the excitation electrical signal into a mechanical vibration signal.

[0070] like Figure 1 , Figure 2 and Figure 3 As shown, the ultrasonic transducer assembly includes an excitation element 210, and first excitation regions 211 (e.g., on both sides of the excitation element 210) are respectively provided on the two side plates. Figure 2 The first excitation region 211 and the second excitation region (not shown in the figure) are arranged opposite to each other. It can be understood that the first excitation region 211 and the second excitation region can cover the entire area of ​​the plate surface of the excitation element 210. When an electric field is applied to the first excitation region 211 and the second excitation region, the charge distribution inside the material changes, thereby causing mechanical motion.

[0071] The ultrasonic transducer assembly 200 further includes a first excitation electrode group, which includes a first electrode 220 and a second electrode 230. The first electrode 220 is disposed in a first excitation region 211, and the second electrode 230 is disposed in a second excitation region. At least the first electrode 220 is an array electrode, and the second electrode 230 can be an array electrode (e.g.,...). Figure 8 and Figure 10As shown), it can also be a full-surface electrode (such as...). Figure 3 (As shown). It needs to be explained that, as... Figure 2 and Figure 3 As shown, the array electrode consists of multiple strip electrodes, which are spaced apart along a first direction. In contrast, the full-coverage electrode is a single, complete electrode that can completely cover the second excitation region.

[0072] Array electrodes and full-coverage electrodes can be printed onto the corresponding excitation areas using a screen printing process. For example... Figure 2 As shown, each strip electrode extends along a second direction and is arranged sequentially along a first direction, with adjacent strip electrodes spaced apart. One end of each strip electrode is connected to a series electrode extending along the first direction to supply power to each strip electrode, thereby forming a structure resembling... Figure 2 The toothed structure is shown. A full-area electrode is laid out within the second excitation region. The first excitation electrode group is electrically connected to the ultrasonic excitation assembly 100. This is understandable, as... Figure 1 In the embodiment shown, the first excitation region 211 is located on the side away from the ultrasonic excitation component 100, and the second excitation region is located on the side close to the ultrasonic excitation component 100. One output port of the ultrasonic excitation component 100 is electrically connected to the strip electrode in the first excitation region 211, and the other output port is electrically connected to the full-coverage electrode in the second excitation region, thereby forming an electric field inside the excitation element 210 to convert the excitation electrical signal into a mechanical vibration signal.

[0073] Depending on the electrode arrangement in the first excitation region 211 and the second excitation region, when the ultrasonic transducer 200 is placed in a resonator for testing, its resonance spectrum exhibits the following three conditions: (Reference) Figure 4 The diagram on the left shows that the first type of resonance spectrum has two resonance peaks. The first resonance peak corresponds to the first resonance frequency. When the frequency of the excitation signal is equal to the first resonance frequency, the exciter 210 generates a Lamb wave field. The second resonance peak corresponds to the second resonance frequency. When the frequency of the excitation signal is equal to the second resonance frequency, the exciter 210 generates a periodic resonance wave field. (Reference) Figure 11 The diagram on the left shows that the second type of resonance spectrum contains only one resonance peak, which corresponds to the first resonance frequency. When the frequency of the excitation signal is equal to the first resonance frequency, the exciter 210 generates a Lamb wave field. (Reference) Figure 9 As shown in the diagram on the left, there is only one resonance peak in the third type of resonance spectrum. This resonance peak corresponds to the second resonance frequency. When the frequency of the excitation signal is equal to the second resonance frequency, the exciter 210 generates a periodic resonance wave field.

[0074] In addition, such as Figure 3 , Figure 8 andFigure 10 As shown, the excitation element 210 can be a piezoelectric plate 213 made of piezoelectric material. The piezoelectric plate 213 is made of PZT (lead cobalt titanate piezoelectric ceramic), Zn3N2, or other piezoelectric materials. The first excitation region 211 and the second excitation region are disposed on opposite side surfaces of the piezoelectric plate 213. Alternatively, as... Figure 12 In the three embodiments, the excitation element 210 includes a main body 214 and a piezoelectric film 215 covering both sides of the main body 214. The first excitation region and the second excitation region are disposed on the side of the piezoelectric film 215 away from the main body 214. The main body 214 is made of non-piezoelectric materials such as silicon and glass, and the piezoelectric film 215 is made of materials such as ZnO and AlN.

[0075] When the Lamb wave acoustic device of the first aspect embodiment of this application is applied to the particle manipulation device of the third aspect embodiment of this application, the frequency of the excitation electrical signal is adjusted to a suitable value by the electronic control component of the particle manipulation device. When the frequency of the excitation electrical signal is equal to the first resonant frequency, the exciter 210 generates a Lamb wave field to drive the particles to move toward the plate surface of the exciter 210; or, when the frequency of the excitation electrical signal is equal to the second resonant frequency, the exciter 210 generates a periodic resonant wave field to drive the particles to suspend on the plate surface of the exciter 210. It can be understood that, under the action of acoustic radiation force, the particles are also arranged in an array spaced apart along the first direction, and the particles converge at the antinodes or nodes of the sound field, forming a particle stream extending along the second direction.

[0076] It is understood that the aforementioned "at least the first electrode 220 is an array electrode, and the second electrode 230 can be an array electrode or a fully-covered electrode" includes the following two implementation methods:

[0077] In the first implementation: the first electrode 220 is an array electrode, and the second electrode 230 is a fully-covered electrode. For example... Figure 3 As shown, when the ultrasonic transducer 200 is placed in a resonator, a resonance spectrum with two significant resonance peaks can be obtained. (Refer to...) Figure 4 The diagram on the left side of the middle panel needs explanation. The first resonance peak corresponds to the A0Lamb mode. In this mode, a Lamb wave field is formed within the ultrasonic transducer 200. The Lamb wave field is a periodic standing wave field parallel to the plate surface and a local gradient field perpendicular to the plate surface, with no leakage in the vertical direction. The second resonance peak corresponds to the Wood's anomaly mode. In this mode, the ultrasonic transducer 200 forms a periodic resonant wave field, which is also a periodic standing wave field parallel to the plate surface and a gradient field perpendicular to the plate surface. However, it leaks in the vertical direction, and the gradient is very low, making it a weak gradient field. The frequencies corresponding to the two resonance peaks are named the first resonant frequency and the second resonant frequency, respectively, in ascending order of frequency.

[0078] It should be noted that Lamb waves are a type of plate wave, characterized by strong anti-interference capabilities and relatively low excitation frequencies, while periodic resonance waves are a type of volume wave. It is important to further outline the differences and characteristics of surface waves, volume waves, and plate waves to clarify the characteristics of Lamb wave fields and periodic resonance wave fields. When sound waves propagate in a medium, those with energy concentrated at the free surface layer of the medium or near the interface between two media are called surface waves. There are many types of these waves, such as Rayleigh waves on solid surfaces and Stonley waves near the interface between two solids. Surface waves propagate only on the surface of semi-infinite media and decay exponentially with increasing depth. Surface waves generally exist at the interface between solids and air. If the solid interface is connected to water, the surface wave transforms into a leaky surface wave upon entering the water, propagating in the form of a volume wave.

[0079] Volume waves are waves that propagate in an infinitely homogeneous medium. There are two types of volume waves: longitudinal waves (also called compression / reduction waves, irrotational waves, tension / compression waves, or P-waves) and transverse waves (also called shear waves, or S-waves). They propagate at their own velocities without waveform coupling. Longitudinal waves can propagate in gaseous, liquid, and solid media. When transverse waves propagate in a medium, the direction of vibration of the medium particles is perpendicular to the direction of wave propagation. Transverse waves can only propagate in media with shear elasticity; therefore, they only exist in highly viscous liquids and solids.

[0080] When sound waves propagate in a plate-like medium, their wave type is called a plate wave. There are various types of plate waves, the main one being the Lamb wave. The propagation medium for Lamb waves is a plate with a finite width and a thickness that is very small compared to the wavelength. During the propagation of a plate wave, particles vibrate along elliptical trajectories on both surfaces of the solid, similar to Rayleigh waves. Lamb waves have symmetrical and asymmetrical wave types. Inside the plate, the vibration of particles varies depending on the wave type. When the wave type is symmetrical, the trajectory of particle vibration is the same as that of a longitudinal wave; when the wave type is asymmetrical, it is similar to that of a transverse wave. Plate waves can propagate in plates with free interfaces; plate waves exist on the upper and lower surfaces and inside the plate.

[0081] Traditional acoustic tweezers are mainly divided into two categories based on the propagation mode of sound waves: bulk acoustic tweezers and surface acoustic wave (SAW) acoustic tweezers. Surface acoustic wave tweezers primarily consist of a piezoelectric crystal and interdigitated metal electrodes covering the crystal surface. When an alternating current signal is applied to the electrodes, the piezoelectric crystal vibrates, generating sound waves that propagate on the surface. Existing SAW acoustic tweezers rely on chips that manipulate surface waves, using two pairs of interdigitated electrodes to form a standing surface wave between them. A slender main channel is placed between the electrodes, positioned perpendicular to the direction of surface wave propagation. This method offers high precision and ease of observation, but requires high-frequency ultrasonic transducers. Bulk acoustic tweezers generally utilize the vibrational sound field generated by piezoelectric materials or speakers in the air to manipulate bulk waves produced in water or air. Bulk waves typically need to be modulated into other forms of sound fields to achieve particle manipulation. For example, adding reflective surfaces or a pair of bulk transducers to form a standing wave, or using acoustic artificial structures to modulate the sound field to form a focused or vortex sound field for particle manipulation.

[0082] When the frequency of the excitation electrical signal of the ultrasonic excitation component 100 of this application is the first resonant frequency, it excites an A0 mode plate wave. Its sound field is attenuated perpendicular to the plate surface, so it is a local gradient sound field. Similar to surface waves, it can enhance the interaction between waves and matter. However, the excitation frequency of the plate wave is much lower than that of the surface wave, and it can be obtained by excitation by the low-frequency exciter 210.

[0083] Next, more specific data will be used to verify the feasibility of applying the Lamb wave acoustic device of this application to a particle manipulation device. It is understood that these specific parameters can be adaptively adjusted according to factors such as the material of the exciter 210, the size of the microspheres, and should not be construed as meaning that the Lamb wave acoustic device of this application is only applicable to the following specific parameters. It should be noted that the particles can be polystyrene microspheres (hereinafter referred to as PS microspheres), silicone spheres, or particles of other materials, with a particle size range of 4 μm to 100 μm.

[0084] The electrode width W = 0.685 mm, the distance between the central axes of adjacent electrodes T = 1.4 mm, and the thickness H of the excitation element 210 = 0.45 mm are selected. According to... Figure 4 The resonance spectrum shown on the left indicates that the ultrasonic transducer 200 of this embodiment has a first resonance frequency f1 = 0.998 MHz and a second resonance frequency f2 = 1.072 MHz. This application further investigates the sound pressure field distribution of the ultrasonic transducer 200 at the two resonance frequencies. Figure 5 As shown in (a), when the frequency of the excitation electrical signal is equal to the first resonant frequency, the ultrasonic transducer 200 forms a periodic standing wave field parallel to the plate surface. This periodic standing wave field is a gradient field perpendicular to the plate surface, and is a local gradient field, further demonstrating its leak-free characteristics; Figure 5(b) shows that when the frequency of the excitation electrical signal is equal to the second resonant frequency, the ultrasonic transducer 200 forms a periodic standing wave field parallel to the plate surface and a gradient field perpendicular to the plate surface. However, leakage occurs in the vertical direction, the gradient is very low, and it is a weak gradient field.

[0085] To reveal the resonance modes at the first resonant frequency, in such... Figure 13 The paper presents the dispersion curves of the exciter 210 with a spacing of T = 0.45 mm between the central axes of adjacent electrodes. Due to Bragg scattering, the leak-free A0 Lamb mode is separated by a band gap at k = 0. When k = 0, the resonance peak f1 = 0.998 MHz at T = 0.45 mm is consistent with the A0 mode on the dispersion curve, thus demonstrating the feasibility of exciting the Lamb wave field at the first resonance frequency.

[0086] To further obtain the force characteristics of the particles around the exciter 210, this application studied the spatial distribution of acoustic radiation force experienced by the particles near the exciter 210 when the frequencies of the excitation electrical signals were 0.998MHz (first resonant frequency) and 1.072MHz (second resonant frequency), respectively. Figure 5 As shown in (c), when the frequency of the excitation electrical signal is 0.998 MHz, the PS microspheres are subjected to an acoustic stabilizing force parallel to the plate surface and an acoustic trapping force perpendicular to the plate surface, which is expected to achieve the trapping and alignment of the microparticles, that is, to make the microparticles move towards the plate surface; Figure 5 As shown in (d), when the frequency of the excitation signal is 1.072 MHz, the PS microspheres are subjected to an acoustic stabilizing force parallel to the plate surface, which is expected to achieve the suspension and alignment of the microspheres, that is, the movement of the microspheres in a direction parallel to the plate surface. It should be explained that the arrows in the figure indicate the direction of the acoustic radiation force on the microspheres, and the gray level indicates the magnitude of the acoustic radiation force on the microspheres.

[0087] Furthermore, this application utilizes the exciter 210 to conduct experiments on capturing and suspending arranged particles. From Figure 6 (a) It can be seen that when no electrical signal is initially applied to the ultrasonic transducer 200, the PS microspheres are randomly arranged on the surface of the exciter 210; as shown in the image. Figure 6 As shown in (b), when the exciter 210 is loaded with a frequency of 0.998 MHz, the PS microspheres are periodically trapped on the surface of the exciter 210; when the exciter 210 is loaded with a frequency of 1.072 MHz, as... Figure 7 As shown, PS microspheres can be periodically suspended in an aqueous solution, wherein... Figure 7 (b) is Figure 7 (a) Side view.

[0088] The second implementation: The first electrode 220 is an array electrode, and the second electrode 230 is also an array electrode. This implementation specifically includes the following two cases: such as... Figure 8 As shown, the strip electrodes of the first electrode 220 and the second electrode 230 are arranged opposite to each other; that is, along the projection from the first electrode 220 to the second electrode 230, the projection area of ​​the strip electrode of the first electrode 220 overlaps with the projection area of ​​the strip electrode of the second electrode 230. Alternatively, as... Figure 10 As shown, the strip electrodes of the first electrode 220 and the second electrode 230 are arranged alternately, that is, the strip electrodes of the first electrode 220 and the spaced regions of the second electrode 230 are arranged opposite each other, and the strip electrodes of the second electrode 230 and the spaced regions of the first electrode 220 are arranged opposite each other.

[0089] Specifically, when the strip electrodes of the first electrode 220 and the second electrode 230 are positioned opposite each other, the ultrasonic transducer 200 is placed in a resonator to obtain a resonance spectrum as shown below. Figure 9 As shown in the left figure, there is only a second resonance peak in the low frequency range, which corresponds to the Wood's anomaly mode. That is, under this electrode distribution mode, when the loading frequency of the ultrasonic transducer 200 is the second resonance frequency, the ultrasonic transducer 200 can generate a Wood's periodic resonance wave field for driving the microparticles to suspend on the plate surface of the exciter 210.

[0090] When the strip electrodes of the first electrode 220 and the second electrode 230 are alternately arranged, the ultrasonic transducer 200 is placed in a resonator to obtain a resonance spectrum as shown below. Figure 11 As shown in the left figure, only the first resonance peak exists in the low-frequency range, corresponding to the leakage-free A0Lamb mode. That is, under this electrode distribution mode, when the loading frequency of the ultrasonic transducer 200 is the first resonance frequency, the ultrasonic transducer 200 can generate a Lamb wave field that traps particles on the plate surface of the exciter 210.

[0091] In other embodiments, such as Figure 14As shown, in addition to the first excitation region 211 and the second excitation region, the exciter 210 also has a third excitation region 212 and a fourth excitation region. The third excitation region 212 and the first excitation region 211 are spaced apart on the same plate of the exciter 210, while the fourth excitation region (not shown) and the second excitation region are spaced apart on another plate of the exciter 210. Furthermore, the third excitation region 212 and the fourth excitation region are arranged opposite to each other. The ultrasonic transducer assembly 200 also includes a second excitation electrode group, which includes a third electrode 240 and a fourth electrode. The third electrode 240 is disposed within the third excitation region 212, and the fourth electrode is disposed within the fourth excitation region. The third electrode 240 and the fourth electrode are electrically connected to the ultrasonic excitation assembly 100 to convert the input excitation electrical signal into a mechanical vibration signal output.

[0092] It should be noted that the third electrode 240 is consistent with the first electrode 220, and the fourth electrode is the same as the second electrode 230. For example, when both the first electrode and the second electrode 230 are array electrodes, and the first electrode 220 and the second electrode 230 are arranged opposite each other, the third electrode 240 and the fourth electrode are also array electrodes and are arranged opposite each other. This results in the formation of identical sound fields on both sides of the excitation element 210, and the two sound fields converge at the intermediate interval to form a standing wave field. That is, the excitation element 210 between the first excitation electrode group and the second excitation electrode group generates a standing wave field. It can be understood that Lamb wave fields can be formed on both sides of the excitation element 210, and the two Lamb wave fields superimpose to form a standing wave Lamb wave field. Alternatively, the two sides of the excitation element 210 can also be periodic resonant wave fields, and the two periodic resonant wave fields superimpose to form a standing wave periodic resonant wave field.

[0093] like Figure 14 The diagram shows the electrode arrangement on one side of the excitation element 210. Both excitation areas on the same plate are equipped with strip electrodes. It should be noted that, to facilitate power supply to each strip electrode, the two series electrodes extend in opposite directions. The different extension directions of the series electrodes do not affect the consistency of the first electrode 220 and the third electrode 240, or the consistency of the second electrode 230 and the fourth electrode.

[0094] In such Figure 14 In the illustrated embodiment, a full-area electrode is disposed on the other side of the plate. At the resonant frequency, a pair of non-leakage mode waves inherently present in the excitation element 210 are excited and propagate. This pair of waves forms a highly localized standing wave Lamb field between the pair of array electrodes. It is understood that particles often reside at the antinodes or nodes of the standing wave field. By adjusting the phase of the excitation electrical signal, a quantitative translation of the antinode or node position can be achieved, thereby driving the directional movement of the particles. Figure 15As shown, particles captured and arranged at antinodes or nodes by acoustic radiation force undergo translation.

[0095] In some embodiments, the spacing T between adjacent strip electrodes has the following relationship with the thickness H of the exciter 210: H / T≤0.35, so as to obtain a better sound field excitation effect.

[0096] In some embodiments, such as Figure 16 As shown, the particle manipulation device also includes a container 300 for storing an acoustic propagation medium containing particles, and the container 300 is in contact with the ultrasonic transducer assembly. The container 300 can be made of PDMS (polydimethylsiloxane) or glass. In other embodiments, the container 300 can also be an elongated prism, consisting of a top base, a bottom base, and four side walls made of PDMS, and its height can be set as needed.

[0097] Furthermore, the particle manipulation device also includes a drive mechanism for connecting to either the ultrasonic transducer 200 or the container 300, and for driving the ultrasonic transducer 200 and the container 300 to move relative to each other. Since the particles are manipulated by the sound field in the ultrasonic transducer 200, they remain stationary relative to the ultrasonic transducer 200 but move relative to the container 300, thereby adjusting the position of the particles in the container 300.

[0098] When the Lamb wave acoustic device of the first aspect of this application is applied to the sensor of the second aspect of this application, the sensor is placed in a liquid sample, and the changes in the density and / or sound velocity of the liquid sample can be sensed according to the changes in the first resonant frequency and / or the second resonant frequency of the acoustic device.

[0099] Specifically, such as Figure 17 As shown, to study the liquid sensing characteristics of the sensor, it was placed in two different liquid samples, and their resonant frequencies were monitored. In the first group of liquid samples, the density increased linearly while the sound velocity remained constant. The second group of liquid samples exhibited the opposite acoustic properties: the sound velocity increased linearly while the density remained constant. Figure 18 (a) and Figure 18 As shown in (b), the two resonant frequencies of the sensor as a function of density and as a function of sound velocity are illustrated. In the first group of liquid samples, the first resonant frequency decreases significantly with increasing density, while the second resonant frequency remains relatively stable. In the second group of liquid samples, the second resonant frequency increases significantly with increasing sound velocity, while the first resonant frequency remains relatively stable. This demonstrates that the sensor is particularly sensitive to liquid mixtures with significant changes in density and sound velocity, and also proves the feasibility of applying Lamb wave acoustic devices to sensors.

[0100] Depending on the arrangement and configuration of the electrodes on the Lamb wave acoustic device, the Lamb wave acoustic device has three resonant frequencies. When the first electrode 220 is an array electrode and the second electrode 230 is a full-coverage electrode, the ultrasonic transducer 200 has a first resonant frequency and a second resonant frequency. When both the first electrode 220 and the second electrode 230 are array electrodes, and the strip electrodes of the first electrode 220 and the second electrode 230 are arranged opposite each other, the ultrasonic transducer 200 has a second resonant frequency. When both the first electrode 220 and the second electrode 230 are array electrodes, and the strip electrodes of the first electrode 220 and the second electrode 230 are arranged alternately, the ultrasonic transducer 200 has a first resonant frequency.

[0101] Based on the three types of Lamb wave acoustic devices mentioned above, they can be applied to different monitoring scenarios. For example, when it is necessary to monitor changes in density and sound velocity, a Lamb wave acoustic device with a first resonant frequency and a second resonant frequency can be used; when it is necessary to monitor only changes in density, a Lamb wave acoustic device with a first resonant frequency can be used; and when it is necessary to monitor only changes in sound velocity, a Lamb wave acoustic device with a second resonant frequency can be used.

[0102] In summary, Lamb wave acoustic devices can be well applied in the sensor field. The first and second resonant frequencies of the ultrasonic transducer 200 are highly sensitive to the density and sound velocity of the liquid outside the exciter 210. Therefore, this sensor can be used to monitor acoustic parameters such as density and sound velocity, thereby reflecting changes in component concentration or sound velocity in the liquid mixture. Furthermore, this sensor is compatible with other microfluidic components. These advantages allow for integration with chip devices, enabling its use in various microfluidic sensing applications.

[0103] The fourth aspect of this application also provides a particle manipulation method that can be applied to the particle manipulation device described in the third aspect of the application, such as... Figure 20 As shown, it includes the following steps:

[0104] S100. Simulation is performed using computer software to obtain optimized electrode parameter information and excitation element parameter information;

[0105] Numerical simulations are performed using finite element method software, such as COMSOL. In the simulation calculations, plane wave radiation boundary conditions were used around the perimeter to reduce the influence of reflected waves on the calculations. The computational model employed pressure acoustics, solid mechanics, and electrostatics modules, while the research model used a frequency domain module. Periodic boundary conditions were used on the left and right boundaries to simulate the periodic structure of the model; plane wave radiation boundary conditions were used on the top and bottom boundaries to simulate open space; the upper surface electrode was selected as a terminal electrode, and the lower surface electrode was selected as a ground electrode; the PS microsphere was located on the upper surface of the low-frequency exciter 210.

[0106] To study the resonant acoustic field characteristics of low-frequency piezoelectric plates, the normalized resonance spectra of ultrasonic transducer components 200 with three different thicknesses H and three different electrode spacings T were theoretically calculated. The thickness and periodicity correlations were discussed, such as... Figure 19 (a) and Figure 19 As shown in (b). The results show that the first resonant frequency f1 increases with the increase of the thickness H of the low-frequency exciter 210, which indicates that the first resonant frequency f1 is generated by the leakage-free A0Lamb mode of the plate; the second resonant frequency f2 is independent of the thickness of the low-frequency exciter 210, but decreases with the increase of the period T of the low-frequency exciter 210, which indicates that the second resonant frequency f2 is generated by periodic resonance.

[0107] The electrode width T, electrode spacing T, and excitation element thickness H are continuously optimized using the controlled variable method.

[0108] S200. Fabricate excitation component 210 according to the excitation component parameter information;

[0109] The activator 210 was procured and polished to a preset thickness H.

[0110] S300. Electrodes are coated on both sides of the excitation element 210 according to the electrode parameter information to form an ultrasonic transducer assembly 200.

[0111] Electrodes were printed on the surface of the low-frequency exciter 210 using screen printing technology, and the samples required for the experiment were obtained after drying.

[0112] S400. By conducting a normalized resonance experiment on the ultrasonic transducer 200, the first resonance frequency f1 and / or the second resonance frequency f2 of the ultrasonic transducer 200 are obtained.

[0113] When the first electrode 220 is an array electrode and the second electrode 230 is a full-coverage electrode, the resonance spectrum of the ultrasonic transducer 200 has two resonance peaks, corresponding to the first resonance frequency f1 and the second resonance frequency f2, respectively. When both the first electrode 220 and the second electrode 230 are array electrodes and are arranged alternately, the resonance spectrum of the ultrasonic transducer 200 has one resonance peak, corresponding to the first resonance frequency f1. When both the first electrode 220 and the second electrode 230 are array electrodes and are aligned, the resonance spectrum of the ultrasonic transducer 200 has one resonance peak, corresponding to the second resonance frequency f2.

[0114] S500: Adjust the frequency of the excitation electrical signal of the ultrasonic excitation component 100 to the first resonant frequency to excite the ultrasonic transducer component 200 to generate a Lamb wave field so that the particles are captured on the plate surface of the excitation element 210; or, adjust the frequency of the excitation electrical signal of the ultrasonic excitation component 100 to the second resonant frequency to excite the ultrasonic transducer component 200 to generate a periodic resonant wave field so as to drive the particles to suspend on the plate surface of the excitation element 210.

[0115] When the frequency of the excitation electrical signal is the first resonant frequency, the ultrasonic transducer 200 excites an A0 Lamb wave field. Particles located in the Lamb wave field are subjected to acoustic radiation forces pointing towards the exciter 210, thereby moving closer to the exciter 210 and eventually adhering to the wall of the container 300. It is understood that the ultrasonic transducer 200 in this mode can be applied to scenarios such as ultrasonic cleaning and targeted blasting of microbubbles. When the frequency of the excitation electrical signal is the second resonant frequency, the ultrasonic transducer 200 excites a periodic resonant wave field. Particles located in the periodic resonant wave field are subjected to acoustic radiation forces parallel to the plate surface of the exciter 210, thereby aligning parallel to the exciter 210, which can be applied to scenarios of targeted drug delivery.

[0116] Furthermore, when each side plate of the excitation element 210 is coated with two electrodes arranged at the same interval, that is, when the excitation element 210 in the first aspect embodiment is provided with a first electrode 220, a second electrode 230, a third electrode 240 and a fourth electrode, the following steps are included after step S500:

[0117] S600: Adjust the phase of the excitation electrical signal to control the translation of particles.

[0118] Understandably, a standing wave field is formed by superimposing two Lamb wave fields or periodic resonant wave fields, thereby enabling the manipulation of particle positions by adjusting the phase. This further increases the flexibility of the particle manipulation device of this application.

[0119] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

Claims

1. A Lamb wave acoustic device, characterized in that, include: An ultrasonic excitation component, wherein the ultrasonic excitation component is used to emit an excitation electrical signal; An ultrasonic transducer assembly includes an exciter and a first excitation electrode group. The exciter has a first excitation region and a second excitation region respectively disposed on both sides. The first excitation electrode group includes a first electrode disposed in the first excitation region and a second electrode disposed in the second excitation region. At least the first electrode is an array electrode, which includes a plurality of strip electrodes spaced apart along a first direction. The first electrode and the second electrode are electrically connected to the ultrasonic excitation assembly to convert the excitation electrical signal into a mechanical vibration signal. Wherein, the ultrasonic transducer has a first resonant frequency, and when the frequency of the excitation electrical signal is equal to the first resonant frequency, the exciter generates a Lamb wave field, which is a local gradient field perpendicular to the plate surface; and / or, the ultrasonic transducer has a second resonant frequency, and when the frequency of the excitation electrical signal is equal to the second resonant frequency, the exciter generates a periodic resonant wave field, which is a periodic standing wave field parallel to the plate surface.

2. The Lamb wave acoustic device according to claim 1, characterized in that, The excitation element is configured as a piezoelectric plate made of piezoelectric material, and the first excitation region and the second excitation region are disposed on opposite side plates of the piezoelectric plate.

3. The Lamb wave acoustic device according to claim 1, characterized in that, The excitation element includes a main body and a piezoelectric film covering both sides of the main body. The first excitation region and the second excitation region are disposed on the side of the piezoelectric film away from the main body. The main body is made of a non-piezoelectric material.

4. The Lamb wave acoustic device according to claim 1, characterized in that, The first electrode is the array electrode, the second electrode is a full-coverage electrode that completely covers the second excitation region, and the ultrasonic transducer has a first resonant frequency that enables the exciter to generate the Lamb wave field and a second resonant frequency that enables the exciter to generate the periodic resonant wave field.

5. The Lamb wave acoustic device according to claim 1, characterized in that, Both the first electrode and the second electrode are array electrodes, and the strip electrodes of the first electrode and the strip electrodes of the second electrode are staggered. The ultrasonic transducer has a first resonant frequency that enables the exciter to generate a Lamb wave field.

6. The Lamb wave acoustic device according to claim 1, characterized in that, Both the first electrode and the second electrode are array electrodes, and the strip electrodes of the first electrode and the strip electrodes of the second electrode are arranged opposite to each other. The ultrasonic transducer has a second resonant frequency that enables the exciter to generate a periodic resonant wave field.

7. The Lamb wave acoustic device according to claim 1, characterized in that, The distance T between adjacent strip electrodes has the following relationship with the thickness H of the excitation element: H / T≤0.

35.

8. A sensor, characterized in that, Includes the Lamb wave acoustic device as described in any one of claims 1 to 7, wherein the sensor is used to detect changes in the physical parameters of the sample under test.

9. The sensor according to claim 8, characterized in that, In response to an increase in the density of the sample under test, the first resonant frequency decreases; and / or, in response to an increase in the sound velocity in the sample under test, the second resonant frequency increases.

10. A particle manipulation device, characterized in that, Including the Lamb wave acoustic device as described in any one of claims 1 to 7, the particle manipulation device is used to manipulate particle movement.

11. The particle manipulation device according to claim 10, characterized in that, When the frequency of the excitation electrical signal is equal to the first resonant frequency, the exciter is excited to generate a Lamb wave field to drive the particle to move toward the surface of the exciter; and / or, when the frequency of the excitation electrical signal is equal to the second resonant frequency, the exciter is excited to generate a periodic resonant wave field to drive the particle to suspend on the surface of the exciter.

12. The particle manipulation device according to claim 10, characterized in that, The plate surface of the excitation element is further provided with a third excitation region spaced apart from the first excitation region and a fourth excitation region spaced apart from the second excitation region. The third excitation region and the fourth excitation region are arranged opposite to each other. The ultrasonic transducer assembly includes a second excitation electrode group, which includes a third electrode disposed in the third excitation region and a fourth electrode disposed in the fourth excitation region. The third electrode and the fourth electrode are respectively electrically connected to the ultrasonic excitation assembly to convert the excitation electrical signal into a mechanical vibration signal. The third electrode is the same as the first electrode, and the fourth electrode is the same as the second electrode, so as to generate a standing wave field between the first excitation electrode group and the second excitation electrode group, and control the translation of the particle by changing the phase of the excitation electrical signal.

13. The particle manipulation device according to claim 10, characterized in that, The particle manipulation device also includes a container for storing an acoustic propagation medium containing the particles, and the container is disposed in contact with the ultrasonic transducer assembly. The particle manipulation device further includes a drive mechanism connected to the ultrasonic transducer or the container. The drive mechanism is used to drive the ultrasonic transducer and the container to move relative to each other, so as to adjust the position of the particles in the container.

14. A particle manipulation method, applied to the particle manipulation device according to any one of claims 10 to 13, characterized in that, It includes the following steps: S100. Simulation is performed using computer software to obtain optimized electrode parameter information and excitation element parameter information; S200. Fabricate the excitation component based on the excitation component parameter information; S300. Electrodes are coated on both sides of the excitation element according to the electrode parameter information to form an ultrasonic transducer assembly. S400. The first resonance frequency and / or the second resonance frequency of the ultrasonic transducer are obtained by conducting a normalized resonance experiment on the ultrasonic transducer. S500, the frequency of the excitation electrical signal of the ultrasonic excitation component is adjusted to the first resonant frequency to excite the ultrasonic transducer component to generate a Lamb wave field, so that the driving particles move toward the plate surface of the excitation element; or, the frequency of the excitation electrical signal of the ultrasonic excitation component is adjusted to the second resonant frequency to excite the ultrasonic transducer component to generate a periodic resonant wave field, so as to drive the particles to suspend on the plate surface of the excitation element.

15. The particle manipulation method according to claim 14, characterized in that, The excitation element has two identical, spaced electrodes coated on each side plate. Following step S500, the following steps are also included: S600. Adjust the phase of the excitation electrical signal to control the translation of the particles.

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