High-precision force-electric coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect

Abstract

The invention discloses a high-precision force-electric coupling resonant tuning fork sensor based on a piezoelectric or inverse piezoelectric effect. The high-precision force-electric coupling resonant tuning fork sensor comprises a tuning fork main body formed by a piezoelectric material, the tuning fork main body comprises a tuning fork base and more than two tuning fork arms arranged on the tuning fork base; at least one exciting electrode and at least one sensing electrode are embedded in each tuning fork arm; all the exciting electrodes are jointly connected to an exciting electrode connecting point through wires respectively; all the sensing electrodes are jointly connected to a sensing electrode connection point through wires respectively; the exciting electrode connecting point and the sensing electrode connecting point are respectively arranged on the tuning fork base so as to be electrically connected with an external wire; and metal coating electrodes with adjustable electrode potentials are arranged on the peripheral surfaces, corresponding to the tuning fork arms, of the tuning fork main body. The method has the characteristics of high robustness, high quality factor, high sensitivity and the like, is suitable for working condition measurement in a severe environment, and is expected to be applied to the fields of petrifaction, food, gas sensing, medicine, scientific research and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of electromechanical coupling sensor equipment, and in particular to a high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect. Background Art

[0002] Traditional liquid density measurement methods such as density bottle method, liquid specific gravity balance method, glass float, etc. generally require manual operation and calculation, which are inefficient and not suitable for continuous online measurement; at the same time, traditional viscosity measurement methods include capillary method, rotation method, falling ball method, etc. These methods are complex in structure and difficult to achieve online measurement; modern measurement methods use the relationship between physical quantities such as liquid medium density, viscosity and pressure, sound waves, rays or vibration frequency to achieve indirect measurement, and convert related physical quantities into electrical signals to achieve online measurement. It is the main measurement technology developed and applied in modern industrial sites. Compared with the existing or traditional oil condition sensor principle, the tuning fork sensor device can easily realize small integration and simultaneously measure four parameters such as viscosity, density, dielectric constant and temperature in various high and low temperature harsh environments. Due to its high stability, high precision and low power consumption, lithium niobate tuning fork has become an important basic component for online frequency measurement. At the same time, because lithium niobate material has better temperature stability and higher mechanical strength, it can work in harsh environmental conditions; and lithium niobate tuning forks have lower phase noise levels, which is very important for some applications that require high frequency stability and accuracy, such as: in-situ online measurement of the physical and chemical properties of electrolytes; however, most of the existing tuning forks are limited to use in conductive solutions (such as lithium ion electrolytes) due to their exposed electrodes. Summary of the invention

[0003] The purpose of the present invention is to provide a high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect to solve the problem that the electrodes of a traditional two-electrode quartz tuning fork are exposed and short circuits are prone to occur when operating in a conductive medium.

[0004] The technical solution adopted by the present invention is: A high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect, comprising a tuning fork body formed of piezoelectric material; the tuning fork body comprises a tuning fork base and two or more tuning fork arms arranged on the tuning fork base; at least one excitation electrode and at least one sensing electrode are embedded inside each tuning fork arm; all the excitation electrodes are connected to the excitation electrode connection point through wires; all the sensing electrodes are connected to the sensing electrode connection point through wires; the excitation electrode connection point and the sensing electrode connection point are respectively arranged on the tuning fork base so as to be electrically connected to external wires; a metal-plated electrode with adjustable electrode potential is arranged on the outer peripheral surface of the tuning fork body corresponding to the tuning fork arm.

[0005] Furthermore, the two tuning fork arms and the tuning fork base are integrally formed.

[0006] Furthermore, the tuning fork body presents a U-shaped structure.

[0007] Furthermore, the tuning fork body is made of lithium niobate (LiNbO3) piezoelectric material; the excitation electrode and the sensing electrode are embedded in the interior of the piezoelectric material LiNbO3 tuning fork, and the metal-plated electrode coated on the outer surface of the tuning fork can be grounded or a polarization voltage (potential is adjustable) can be applied according to the working mode.

[0008] Furthermore, the sensing electrode and the excitation electrode are formed of any metal electrode material (Au / Pt / Cu / Al, etc.), and the metal-plated electrode is an inert metal that is resistant to oxidation; or a coating that has an adsorption effect on the gas / liquid medium environment.

[0009] Furthermore, there is no limit to the embedding processing technology of the sensing electrode and the excitation electrode, and the geometric structure can be adjusted to an embedding structure arranged parallel to the vibration direction of the tuning fork or arranged perpendicular to the vibration direction according to actual detection requirements.

[0010] Furthermore, the cross sections of the sensing electrode and the exciting electrode are rectangular.

[0011] Furthermore, the excitation method and detection method include but are not limited to: 1. Applying voltage excitation between the excitation electrode and the outer metal-coated electrode to detect the inverse piezoelectric response electrical signal between the sensing electrode and the outer metal-coated electrode; 2. Directly applying an excitation signal between the excitation electrode and the sensing electrode to test the impedance response, and the outer metal-coated electrode is grounded to shield the stray electric field.

[0012] Furthermore, the resonance frequency of the tuning fork is tuned by the dimensions of the tuning fork length, the geometry of the swing arm, and the thickness of the vibrating swing arm.

[0013] Furthermore, the tuning fork can be used to simultaneously measure the viscosity and density of a gas / liquid, or the increase in effective mass on the tuning fork surface caused by the composition of the solution during an electrochemical process.

[0014] Furthermore, the potential of the metal-plated electrode wrapped around the outside of the tuning fork is controllable and can be used for electrode-electrolyte interface viscosity and density detection in electrochemical environments, including but not limited to: corrosion, catalysis, gas sensors, supercapacitors, lithium batteries and new aqueous zinc-ion batteries.

[0015] The present invention adopts the above technical solution. Compared with the traditional two-electrode lithium niobate tuning fork, the present invention innovatively adds a third end electrode as the working electrode of the electrochemical system, embeds the excitation electrode and the sensing electrode of the tuning fork inside the piezoelectric material lithium niobate tuning fork, and wraps a layer of inert metal plating on the outside to improve its measurement sensitivity in the liquid, ensure the chemical stability of the exposed electrode, and prevent corrosion and short circuit of the electrode. The working electrode can participate in the electrochemical system to monitor the physical and chemical process of the surface interface between the working electrode and the electrolyte, and realize the in-situ coordinated measurement of the rheological properties of the liquid medium in various complex electrochemical environments. It has great significance and application prospects for the early warning of electrochemical failures such as fire and flatulence of the battery system, and the mechanism analysis of the capacity decay of lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments; Figure 1 It is a schematic structural diagram of a high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect of the present invention; Figure 2 A top view of a high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to the present invention; Figure 3 It is a cross-sectional schematic diagram of the tuning fork body corresponding to the tuning fork arm portion of the present invention; Figure 4 It is a schematic diagram of an embodiment of the present invention applied to device measurement of an integrated small liquid pool; Figure 5 It is a schematic diagram of the resonance spectrum of an implementation example of resonance peak measurement and viscosity density fitting in diethyl carbonate organic solvent.

[0017] Figure markings: 1-metal-plated electrode, 2-excitation electrode, 3-sensing electrode, 4-tuning fork body, 5-rubber ring, 6-PVC electrical insulating tape, 71-excitation electrode connection point, 72-sensing electrode connection point, 8-glass protective cover, 9-RBG pin 3pin pin, 10-wire connected to the sensing electrode, 11-wire connected to the metal-plated electrode, 12-wire connected to the excitation electrode, 13-pin pre-insulated terminal. Implementation

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0019] like Figures 1 to 5As shown in one, the present invention discloses a high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect, which includes a tuning fork body 4 formed of piezoelectric material; the tuning fork body 4 includes a tuning fork base and two or more tuning fork arms arranged on the tuning fork base; each tuning fork arm is embedded with at least one excitation electrode 2 and at least one sensing electrode 3; all the excitation electrodes 2 are respectively connected to the excitation electrode connection point 71 through wires; all the sensing electrodes 3 are respectively connected to the sensing electrode connection point 72 through wires; the excitation electrode connection point 71 and the sensing electrode connection point 72 are respectively arranged on the tuning fork base so as to be electrically connected to the external wire; the outer peripheral surface of the tuning fork body 4 corresponding to the tuning fork arm is provided with a metal-plated electrode 1 with adjustable electrode potential.

[0020] Furthermore, the two tuning fork arms and the tuning fork base are integrally formed.

[0021] Furthermore, the tuning fork body 4 presents a U-shaped structure.

[0022] Furthermore, the tuning fork body 4 is made of lithium niobate (LiNbO3) piezoelectric material; the excitation electrode 2 and the sensing electrode 3 are embedded in the interior of the piezoelectric material LiNbO3 tuning fork, and the metal-plated electrode coated on the outer surface of the tuning fork can be grounded or a polarization voltage (potential adjustable) can be applied according to the working mode.

[0023] Furthermore, the sensing electrode 3 and the excitation electrode 2 are formed of any metal electrode material (Au / Pt / Cu / Al, etc.), and the metal-plated electrode is an inert metal electrode that is resistant to oxidation; or a coating that has an adsorption effect on the gas / liquid medium environment.

[0024] Furthermore, the embedding processing technology of the sensing electrode 3 and the excitation electrode 2 is not limited, and the geometric structure can be adjusted to an embedding structure arranged parallel to the vibration direction of the tuning fork or arranged perpendicular to the vibration direction according to actual detection requirements.

[0025] Furthermore, if Figure 3 As shown, the cross-sections of the sensing electrode 3 and the excitation electrode 2 are rectangular.

[0026] Furthermore, the excitation method and detection method include but are not limited to: 1. Applying voltage excitation between the excitation electrode 2 and the outer metal-coated electrode to detect the inverse piezoelectric response electrical signal between the sensing electrode 3 and the outer metal-coated electrode; 2. Directly applying an excitation signal between the excitation electrode 2 and the sensing electrode 3 to test the impedance response, and the outer metal-coated electrode is grounded to shield the stray electric field.

[0027] Furthermore, the resonance frequency of the tuning fork is tuned by the dimensions of the tuning fork length, the geometry of the swing arm, and the thickness of the vibrating swing arm.

[0028] Furthermore, the tuning fork can be used to simultaneously measure the viscosity and density of a gas / liquid, or the increase in effective mass on the tuning fork surface caused by the composition of the solution during an electrochemical process.

[0029] Furthermore, the potential of the outer metal-plated electrode of the tuning fork is controllable and can be used for electrode-electrolyte interface viscosity and density detection in electrochemical environments, including but not limited to: corrosion, catalysis, gas sensors, supercapacitors, lithium batteries and new aqueous zinc-ion batteries.

[0030] like Figure 4 As shown, the viscosity and density measurement of diethyl carbonate is taken as an example. The parameters obtained by calibration are used to perform real-time nonlinear fitting of the sweep frequency curve, so that the viscosity and density of the liquid to be measured can be measured in real time. The wire 10 of the sensing electrode 3, the wire 11 connected to the inert metal electrode 1, and the wire 12 connected to the excitation electrode 2 are insulated and bundled by PVC electrical insulation tape 6, and the rubber ring 5 sets the bundled PVC electrical insulation tape 6 on the outer wall of the glass protective cover 8; there are more than two rubber rings 5, so as to better fix the corresponding wires to the outer wall of the glass protective cover 8. First, use a pipette to inject deionized water into the glass protective cover 8 to clean the tuning fork sensor to ensure that the tuning fork sensor is clean and avoid internal dirt that changes the resonance period; use a known resistance resistor to perform impedance calibration, and scan the resonance peak of the tuning fork sensor in the air within the calibration frequency range to obtain the spectrum in the air; finally, connect the wire 12 connected to the excitation electrode 2 and the wire 10 of the sensing electrode 3 to the corresponding pins of the RBG pin 9 (3pin pin). The wire 11 connected to the inert metal electrode 1 is connected to the pin-type pre-insulated terminal 13; the RBG pin 9 and the pin-type pre-insulated terminal 13 are respectively connected to the corresponding positions on the evaluation board, and diethyl carbonate is injected into the glass protective cover 8 with a pipette gun to perform resonance peak scanning to obtain the following Figure 5 Resonance spectrum shown; The present invention adopts the above technical solution, and the main body is made of LiNbO3 piezoelectric material. Compared with traditional quartz tuning forks, it has better temperature stability and higher mechanical strength, so that it can work under harsh environmental conditions. The present invention has a low phase noise level and is suitable for application scenarios with high requirements for frequency stability and accuracy. The present invention adopts a three-electrode structure to embed the sensing electrode and the excitation electrode inside the LiNbO3 tuning fork to protect them from the influence of the liquid environment, and can realize online detection of viscosity and density in a conductive solution environment. The overall external exposed surface of the tuning fork with a three-electrode structure of the present invention is coated with an inert metal electrode, and its potential is adjustable. It can be used as a working electrode in an electrochemical system to realize the coordinated detection of mass transfer and charge transfer on the surface of the working electrode in the electrochemical system.

[0031] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

Claims

1. A high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect, characterized in that: The invention comprises a tuning fork body formed of piezoelectric material; the tuning fork body comprises a tuning fork base and two or more tuning fork arms arranged on the tuning fork base; at least one excitation electrode and at least one sensing electrode are embedded inside each tuning fork arm; all the excitation electrodes are connected to the excitation electrode connection point through wires; all the sensing electrodes are connected to the sensing electrode connection point through wires; the excitation electrode connection point and the sensing electrode connection point are respectively arranged on the tuning fork base so as to be electrically connected to the external wires; and a metal-plated electrode with adjustable electrode potential is arranged on the outer peripheral surface of the tuning fork body corresponding to the tuning fork arm.

2. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The two tuning fork arms and the tuning fork base are formed in one piece.

3. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The tuning fork body has a U-shaped structure.

4. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The tuning fork body is made of piezoelectric material of lithium niobate; the excitation electrode and the sensing electrode are embedded in the tuning fork of piezoelectric material lithium niobate.

5. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The sensing electrode and the excitation electrode are formed of any metal electrode material, and the metal-plated electrode is an inert metal that is resistant to oxidation; or a coating that has an adsorption effect on the gas / liquid medium environment.

6. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The sensing electrode and the exciting electrode are adjusted to an embedded structure arranged parallel to the vibration direction of the tuning fork or perpendicular to the vibration direction according to actual detection requirements.

7. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The excitation method and detection method include:

1. Applying voltage excitation between the excitation electrode and the outer metal-plated electrode to detect the inverse piezoelectric response electrical signal between the sensing electrode and the outer metal-plated electrode; 2. Applying an excitation signal directly between the excitation electrode and the sensing electrode to test the impedance response, and the outer metal-plated electrode is grounded to shield the stray electric field.

8. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: The resonant frequency of the tuning fork is tuned by the dimensions of the tuning fork length, the geometry of the swing arm, and the thickness of the vibrating swing arm.

9. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 1, characterized in that: Tuning forks are suitable for simultaneous measurement of viscosity and density of gases / liquids, or for the increase in effective mass on the fork surface caused by solution composition in electrochemical processes.

10. The high-precision electromechanical coupling resonant tuning fork sensor based on piezoelectric or inverse piezoelectric effect according to claim 9, characterized in that: The metal-plated electrode with adjustable electrode potential is suitable for electrode-electrolyte interface viscosity and density detection in electrochemical environments, including corrosion, catalysis, gas sensors, supercapacitors, lithium batteries and new aqueous zinc-ion batteries.

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