Electrothermal micro-motion platform integrated with piezoelectric feedback and position detection method thereof

Abstract

The invention discloses an electrothermal micro-motion platform integrated with piezoelectric feedback and a position detection method thereof, and belongs to the technical field of micro electro mechanical systems, and the platform comprises a peripheral supporting structure, an electrothermal driving structure, a micro-platform, and a piezoelectric position detection structure used for detecting the position and the motion state of the micro-platform. According to the invention, the piezoelectric position detection structure and the electrothermal micro-motion platform are integrated, so that attitude information of a deflection angle and a deflection direction of the micro-motion structure can be stably obtained in real time and with high precision under the condition that the motion of the micro-motion structure is not influenced, and the complexity of a closed-loop control attitude feedback circuit of a device and a system thereof can be remarkably reduced; the structure and the size of related application products are optimized, and miniaturization and light weight of devices are achieved.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical technology, and in particular to an electrothermal micro-motion platform with integrated piezoelectric feedback and a position detection method thereof. Background Art

[0002] The micro-drive structure using micro-electro-mechanical system (MEMS) has the advantages of small size, high reliability, low power consumption, and easy batch manufacturing. The micro-drive platform composed of it is widely used in many MEMS devices. According to different driving methods, MEMS micro-motion platforms can be divided into four categories: electrostatic, piezoelectric, electromagnetic, and electrothermal. In comparison, the electrothermal drive method only requires a lower input voltage to achieve a larger driving force and displacement. It is often used in MEMS devices such as micromirrors, micro-tweezers, and micro-switches. It has received extensive attention and in-depth research in the fields of spectrometers, biomedicine, and signal processing.

[0003] However, the electrothermal drive method also has some shortcomings: the high operating temperature makes the actuator very easy to oxidize, and the material creep and hysteresis effects are obvious, resulting in a decrease in its stability and linear control ability, reducing the response speed and control accuracy of the system. Although the use of Cu / W material combination with a high Young's modulus and melting point can effectively enhance the mechanical stiffness of the actuator, this material combination is difficult to meet the long-term stability and large deformation output of the actuator. The material combination based on Al and SiO2 has good high-temperature oxidation resistance and a large difference in material temperature expansion coefficient. It can provide good long-term stability and large deformation output. It is a commonly used material combination. However, it has problems such as slow response speed (about 60ms) and low large-range scanning frequency (within 10Hz).

[0004] In order to further improve the response speed and control accuracy of the electrothermal micro-motion platform drive, introducing the actuator position information feedback in the device or system to form a closed-loop control is another solution besides "material combination". However, there are still many pain points in the existing position detection methods: 1) The detection method based on optical reflection and interference is highly dependent on the external optical path, and has high requirements for alignment and assembly at the system level; 2) In the detection method based on electromagnetic coupling, the energy loss caused by eddy current will significantly reduce the Q value of the coil (parameter of inductance quality), resulting in a decrease in detection sensitivity under the same electromagnetic signal excitation, and even a detection blind area; 3) The position detection method based on capacitance has the problem that a high-precision external detection circuit must be used because the capacitance change caused by movement is too small; 4) The piezoresistive position detection method has the problem of incompatibility with the target electrothermal actuator because most of the materials used cannot withstand temperatures above 125°C.

[0005] It can be seen that the existing position detection methods have deficiencies in system integration, detection circuits, material compatibility, etc. How to more effectively detect the position of the electrothermal micro-motion platform is a difficult problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to overcome the technical problems existing in the position detection method of the existing electrothermal micro-motion platform, and to provide an electrothermal micro-motion platform with integrated piezoelectric feedback and a position detection method thereof.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] In a first aspect, an electrothermal micro-motion platform with integrated piezoelectric feedback is provided, comprising a peripheral support structure, an electrothermal drive structure, a micro-platform, and a piezoelectric position detection structure for detecting a position and a motion state of the micro-platform.

[0009] In some embodiments, the piezoelectric position sensing structure is composed of a conductive material and a piezoelectric material.

[0010] Preferably, the piezoelectric position detection structure is formed by sequentially stacking a conductive material, a piezoelectric material, and a conductive material to form a sandwich detection structure.

[0011] Preferably, the piezoelectric position detection structure is a composite layered detection structure formed by multiple alternating stacking of conductive materials and piezoelectric materials.

[0012] Preferably, the piezoelectric material is a composite material composed of one or more of bismuth layered structure piezoelectric ceramics, ANbO3 (alkali metal niobate compound), PZT, ZnO, LiTaO3, AlN, AlScN, GaN, BaTiO3, PVDF, and BSPT.

[0013] In some embodiments, the piezoelectric position detection structure is a surface acoustic wave detection structure or a bulk acoustic wave detection structure.

[0014] Preferably, the surface acoustic wave detection structure is a surface acoustic wave detection structure composed of Rayleigh Wave, Love Wave, Sheared Horizontal Wave, Surface Transverse Wave, or a bulk acoustic wave detection structure composed of bulk acoustic wave.

[0015] In a second aspect, a method for detecting the position of the electrothermal micro-motion platform is provided, the method comprising:

[0016] The piezoelectric position detection structure is used to detect the position and motion state of the micro-platform.

[0017] In some embodiments, the method of detecting the position and motion state of the micro-platform using a piezoelectric position detection structure includes:

[0018] When the electrothermal drive structure is driven by an external electrical signal, electrical energy will be converted into thermal energy, and further converted into mechanical energy to make the electrothermal drive structure move, and drive the micro-platform to deflect, and at the same time cause the strain state of the piezoelectric position detection structure to change. Due to the piezoelectric principle, the strain caused will be converted into electric charge and enriched on the conductive material of the piezoelectric position detection structure. The amount of charge generated is positively correlated with the strain size, and the electrical polarity of the conductive material is related to the direction of the strain. By introducing the charge into the charge amplifier, a voltage or current signal can be obtained, and the relationship between the voltage or current amplitude (or phase, frequency) and the deflection angle of the micro-platform can be further established. The deflection angle of the micro-platform when the corresponding electrothermal drive structure acts can be determined by measuring the corresponding induced voltage or current. Similarly, the various deflection angles of the micro-platform when multiple electrothermal drive structures act alone or simultaneously can also be obtained. Since the size of the micro-platform is known, after obtaining the deflection angles in each direction, the position and state of the micro-platform can be finally analyzed through spatial geometry.

[0019] In some embodiments, the method of detecting the position and motion state of the micro-platform using a piezoelectric position detection structure includes:

[0020] When the electrothermal drive structure is working, it will cause strain in the piezoelectric position detection structure (surface acoustic wave device or bulk acoustic wave device). According to the perturbation theory, the material constant of the substrate of the piezoelectric position detection structure will change, causing the frequency (or phase, amplitude) of the elastic wave to change. By establishing the relationship between the frequency (or phase, amplitude) and the deflection angle and strain size (direction, frequency) of the micro-platform when a single electrothermal drive structure acts, the deflection angle of the micro-platform when the corresponding electrothermal drive structure acts can be determined by measuring the frequency (or phase, amplitude). Similarly, the deflection angles of the micro-platform when multiple electrothermal drive structures act alone or simultaneously can also be obtained. Since the size of the micro-platform is known, after obtaining the deflection angles in each direction, the position and state of the micro-platform can be finally analyzed through spatial geometry.

[0021] It should be further explained that the technical features corresponding to the above options can be combined or replaced with each other to form a new technical solution if there is no conflict.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention integrates the piezoelectric position detection structure with the electrothermal micro-motion platform in an integrated manner. It can not only obtain the micro-platform deflection angle, deflection direction and other posture information in real time, stably and with high precision without affecting the movement of the micro-platform, but also significantly reduce the complexity of the device and its closed-loop control feedback circuit. At the same time, it plays an important role in optimizing the structure and size of related application products, and realizing the miniaturization and lightweight of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of an electrothermal micro-motion platform with integrated piezoelectric feedback according to an embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of an electrothermal micro-motion platform for position detection using a sandwich detection structure according to an embodiment of the present invention;

[0026] Figure 3 It is a schematic structural diagram of an electrothermal micro-motion platform for position detection using a surface acoustic wave detection structure according to an embodiment of the present invention;

[0027] Figure 4 This is a relationship diagram between the driving voltage and temperature of the electrothermal driving structure 2 under the action of an electrical signal shown in an embodiment of the present invention;

[0028] Figure 5 It is a schematic diagram showing the electrothermal drive structure 2 and the micro-platform 4 undergoing mechanical motion under the action of an electrical signal according to an embodiment of the present invention;

[0029] Figure 6 This is a diagram showing the relationship between the displacement generated by the electrothermal drive structure 2 and the stress on the piezoelectric position detection structure when a periodic time-varying electrical signal acts according to an embodiment of the present invention;

[0030] Figure 7 This is a relationship diagram of the stress on the piezoelectric position detection structure 3 and its induced voltage when a periodic time-varying electrical signal acts according to an embodiment of the present invention;

[0031] Figure 8 A diagram showing the relationship between the induced voltage of the piezoelectric position detection structure and the deflection angle of the micro-platform 4 according to an embodiment of the present invention;

[0032] Fig. 9 is a graph showing the relationship between the resonant frequency of the acoustic phenotyping detection structure and the deflection angle of the micro-platform 4 according to an embodiment of the present invention;

[0033] In the figure: 1-peripheral supporting structure; 2-electrothermal driving structure; 3-piezoelectric position detection structure; 4-micro-platform; 3a-conductive material; 3b-piezoelectric material. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various configurations. 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.

[0035] It should be noted that the defects existing in the solutions in the above-mentioned prior art are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed in the embodiments of the present application for the above-mentioned problems below should all be the contributions made by the inventor to the present application in the process of invention and creation, and should not be understood as technical contents known to technical personnel in this field.

[0036] In view of the technical problems pointed out in the background technology, the embodiments provided by the present invention are as follows:

[0037] In an exemplary embodiment, an electrothermal micromotion platform with integrated piezoelectric feedback is provided, referring to Figure 1 , including a peripheral support structure, an electrothermal drive structure, and a micro-platform. The peripheral support structure is also provided with a piezoelectric position detection structure for detecting the position and motion state of the micro-platform. The peripheral support structure 1 is used to provide mechanical support for the entire electrothermal micro-motion platform; the electrothermal drive structure 2 is applied with an electrical drive signal from the outside to convert electrical energy into thermal energy, and further converts it into mechanical energy to drive the micro-platform 4 to complete unidirectional movement, multi-directional tilting movement, and vertical lifting movement; the piezoelectric position detection structure 3 has high strain sensitivity and high electromechanical conversion efficiency, and can convert strain into electrical signals; under the action of the electrothermal drive structure 2, the micro-platform 4 has the ability to move in one direction, tilt in multiple directions, and move in a vertical lifting manner.

[0038] Furthermore, in the electrothermal micro-motion platform designed in the present invention, the specific form of the micro-platform 4 can be a micro-mirror, micro-tweezers, micro-cage or micro-cantilever; for the structural forms of micro-mirror, micro-tweezers and micro-cantilever, the micro-platform 4 is mechanically connected to the peripheral supporting structure 1 through the electrothermal drive structure 2, and the movement state of the micro-platform 4 is driven by the electrothermal drive structure 2; for the structural form of a micro-cage, the micro-platform 4 is integrated with the electrothermal drive structure 2 to form a whole, and has both electrothermal drive and movement functions.

[0039] Furthermore, the sensing method of the piezoelectric position detection structure 3 for strain may be a detection method that directly utilizes the piezoelectric principle, or may be a detection method that indirectly utilizes the piezoelectric principle.

[0040] In some examples, reference Figure 2 The present invention provides an electrothermal micro-motion platform with integrated piezoelectric position feedback, wherein the micro-platform 4 is a structure of a micro-mirror, micro-tweezers, and micro-cantilever beam. The piezoelectric position detection structure 3 is located on the peripheral support structure 1, and directly uses the piezoelectric principle to perform position detection. Specifically, the piezoelectric position detection structure 3 is composed of a conductive material and a piezoelectric material, and its structure can be a sandwich detection structure formed by stacking conductive materials, piezoelectric materials, and conductive materials in sequence, or a composite layered detection structure formed by multiple alternating stacking of conductive materials and piezoelectric materials; at the same time, the piezoelectric position detection structure 3 can be composed of a conductive material and a piezoelectric material, or can be composed of a plurality of different conductive materials and a plurality of different piezoelectric materials to meet different mechanical, electrical, acoustic, and thermal requirements.

[0041] The position detection method is as follows:

[0042] When a single electrothermal drive structure 2 is driven by an external electrical signal, electrical energy will be converted into thermal energy (see Figure 4 ), which is further converted into mechanical energy to move the electrothermal drive structure 2 and drive the micro-platform 4 to deflect (see Figure 5 ), and at the same time, the strain state of the piezoelectric position detection structure 3 changes, see Figure 6 Due to the piezoelectric principle, the strain caused will be converted into electric charge and enriched on the conductive material of the piezoelectric position detection structure 3. The amount of charge generated is positively correlated with the strain size, and the electrical polarity of the conductive material is related to the direction of the strain. For details, see Figure 7 By introducing the charge into the charge amplifier, a voltage or current signal can be obtained, and the relationship between the voltage or current amplitude (or phase, frequency) and the deflection angle of the micro-platform 4 can be further established. Then, the deflection angle of the micro-platform 4 when the corresponding electrothermal drive structure 2 acts can be determined by measuring the corresponding induced voltage or current. Figure 8 Similarly, the various deflection angles of the micro-platform 4 when multiple electrothermal drive structures 2 act alone or simultaneously can also be obtained. Since the size of the micro-platform 4 is known, after obtaining the deflection angles in various directions, the position and state of the micro-platform 4 can be finally analyzed through spatial geometry.

[0043] In some examples, reference Figure 3The present invention provides another electrothermal micro-motion platform with integrated piezoelectric position feedback, which is based on the micro-platform 4 being a micro-mirror, micro-tweezers, and micro-cantilever beam. The platform indirectly uses the piezoelectric principle to detect the position. The piezoelectric position detection structure 3 is a surface acoustic wave detection structure or a bulk acoustic wave detection structure, wherein the surface acoustic wave detection structure is a surface acoustic wave detection structure composed of Rayleigh Wave, Love Wave, Sheared Horizontal Wave, and Surface Transverse Wave, and the bulk acoustic wave detection structure is a bulk acoustic wave detection structure composed of bulk acoustic wave.

[0044] The position detection method is as follows:

[0045] When a single electrothermal drive structure 2 is working, it will cause strain in the piezoelectric position detection structure 3 (sound surface device). According to the perturbation theory, the material constant of the substrate of the piezoelectric position detection structure 3 will change, causing the frequency (or phase, amplitude) of the elastic wave to change. By establishing the relationship between the frequency (or phase, amplitude) and the deflection angle and strain size (direction, frequency) of the micro-platform 4 when the corresponding electrothermal drive structure 2 acts, when the frequency (or phase, amplitude) is measured, the deflection angle of the micro-platform 4 when the electrothermal drive structure 2 acts can be determined. For details, see Fig. 9 Similarly, the various deflection angles of the micro-platform 4 when multiple electrothermal drive structures 2 act alone or simultaneously can also be obtained. Since the size of the micro-platform 4 is known, after obtaining the angles in various directions, the position and state of the micro-platform 4 can be finally analyzed through spatial geometry.

[0046] In some examples, the piezoelectric position detection structure 3 is specifically positioned according to the micro-motion platform design, including but not limited to near the connection between the peripheral support structure 1 and the electrothermal drive structure 2, on the electrothermal drive structure 2, and near the connection between the micro-platform 4 and the electrothermal drive structure 2, for detecting the strain caused by the movement of the electrothermal drive structure 2, and ultimately obtaining the position and status information of the micro-platform 4.

[0047] The above specific implementation methods are detailed descriptions of the present invention. It cannot be determined that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. An electrothermal micro-motion platform with integrated piezoelectric feedback, comprising a peripheral support structure, an electrothermal drive structure, and a micro-platform, characterized in that: The peripheral support structure is also provided with a piezoelectric position detection structure for detecting the position and motion state of the micro-platform.

2. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 1, characterized in that: The piezoelectric position detection structure is composed of a conductive material and a piezoelectric material.

3. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 2, characterized in that: The piezoelectric position detection structure is a three-layer structure formed by sequentially stacking a conductive material, a piezoelectric material, and a conductive material.

4. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 2, characterized in that: The piezoelectric material is a composite material composed of one or more of bismuth layered structure piezoelectric ceramics, ANbO3 (alkali metal niobate compound), PZT, ZnO, LiTaO3, AlN, AlScN, GaN, BaTiO3, PVDF, and BSPT piezoelectric materials.

5. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 2, characterized in that: The piezoelectric position detection structure is a sandwich detection structure composed of conductive materials and piezoelectric materials or a composite layered detection structure formed by multiple alternating stacking.

6. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 1, characterized in that: The piezoelectric position detection structure is a surface acoustic wave detection structure or a bulk acoustic wave detection structure.

7. The electrothermal micro-motion platform with integrated piezoelectric feedback according to claim 6, characterized in that: The surface acoustic wave detection structure is a surface acoustic wave detection structure formed by Rayleigh waves, Love waves, horizontal shear waves, and surface shear waves, or a bulk acoustic wave detection structure formed by bulk acoustic waves.

8. A method for detecting the position of the electrothermal micro-motion platform with integrated piezoelectric feedback as claimed in claim 5, characterized in that: The method of using a piezoelectric position detection structure to detect the position and motion state of the micro-motion structure includes: The piezoelectric position detection structure is strained by the electrothermal driven structural force, and charges are generated according to the piezoelectric principle. The amount of charge is positively correlated with the strain, and the electrical polarity is related to the direction of the strain. The generated charges are enriched on the conductive material, and the charges are introduced into a charge amplifier to be converted into a voltage or current signal. By establishing a relationship between the voltage or current and the stress on the piezoelectric position detection structure, and a relationship between the stress on the piezoelectric position detection structure and the deflection angle of the micro-platform, the position and motion state of the micro-platform can be determined by measuring the voltage or current.

9. A method for detecting the position of the electrothermal micro-motion platform with integrated piezoelectric feedback as claimed in claim 7, characterized in that: The method of using a piezoelectric position detection structure to detect the position and motion state of the micro-platform includes: When the electrothermal driving structure is working, it causes strain in the piezoelectric position detection structure. According to the perturbation theory, the material constant of the substrate of the piezoelectric position detection structure will change, causing the frequency of the elastic wave to change. By establishing the relationship between the frequency of the electrical signal generated by the piezoelectric effect of the piezoelectric position detection structure and the stress on the piezoelectric position detection structure, and the relationship between the stress on the piezoelectric position detection structure and the deflection angle of the micro-platform, the position and motion state of the micro-platform can be determined by measuring the frequency of the electrical signal.

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