Triboelectricity type self-sensing piezoelectric micro valve and flow monitoring method

Abstract

The invention discloses a triboelectric type self-sensing piezoelectric micro valve and a flow monitoring method. Self-sensing flow monitoring can be achieved. The triboelectric self-sensing piezoelectric micro valve comprises a shell, a piezoelectric vibrator and a friction sensing unit, the shell is provided with a liquid inlet and a liquid outlet, the piezoelectric vibrator and the friction sensing unit are arranged in the shell, and the piezoelectric vibrator is arranged at the liquid inlet; the friction sensing unit comprises a first power generation unit and a second power generation unit which are oppositely arranged, the first power generation unit is fixedly connected to the inner wall of the shell, the second power generation unit is fixedly connected to the piezoelectric vibrator, and the piezoelectric vibrator is used for driving the second power generation unit to make contact with or be away from the first power generation unit; the piezoelectric vibrator deforms under the action of the driving voltage to open the liquid inlet, and enables the second power generation unit to be in contact with the first power generation unit to generate a first electric signal; or, the piezoelectric vibrator deforms to close the liquid inlet under the control of the driving voltage, and enables the second power generation unit to be far away from the first power generation unit to generate a second electric signal.

Description

Technical Field

[0001] The present application relates to the technical field of liquid flow monitoring, and in particular to a triboelectric self-sensing piezoelectric microvalve and a flow monitoring method. Background Art

[0002] Liquid flow valves usually control the flow of fluids by mechanical or electronic means. For example, the flow of fluid can be adjusted by changing the opening of the valve, thereby realizing flow monitoring and control. There are various types of valves in terms of driving methods, such as electromagnetic drive, electrostatic drive, thermal drive and other methods. Among them, the electromagnetic drive type is easily disturbed by the external environment and has high power consumption. Although the electrostatic drive type has the characteristics of fast response and low power consumption, its highly nonlinear control characteristics are not conducive to achieving proportional control. The thermal drive type is easily affected by fluid changes and has poor stability. In addition, the valve has a certain sensitivity to the viscosity and temperature of the medium. For media with high viscosity, the accuracy of flow regulation will be greatly affected. Therefore, it is urgent to provide a triboelectric self-sensing piezoelectric microvalve with high precision. Summary of the invention

[0003] The triboelectric self-sensing piezoelectric microvalve and flow monitoring method provided by the present application combine piezoelectric ceramics with triboelectric nanogenerators, and propose a new triboelectric self-sensing piezoelectric microvalve, which can realize self-sensing flow monitoring, and the flow monitoring accuracy can reach the microliter level. In addition, the friction sensing unit is integrated with the piezoelectric vibrator, which improves the space utilization rate and is conducive to the miniaturization and integration of the device.

[0004] On the one hand, an embodiment of the present application provides a friction electric self-sensing piezoelectric microvalve including a shell, a piezoelectric vibrator and a friction sensing unit, wherein the shell has a liquid inlet and a liquid outlet, the piezoelectric vibrator and the friction sensing unit are arranged in the shell, and the piezoelectric vibrator is arranged at the liquid inlet; the friction sensing unit includes a first power generation unit and a second power generation unit arranged opposite to each other, the first power generation unit is fixedly connected to the inner wall of the shell, and the second power generation unit is fixedly connected to the piezoelectric vibrator, and the piezoelectric vibrator is used to drive the second power generation unit to contact or move away from the first power generation unit; the piezoelectric vibrator is deformed under the action of a driving voltage to open the liquid inlet, and makes the second power generation unit contact the first power generation unit to generate a first electrical signal; or, the piezoelectric vibrator is deformed under the control of the driving voltage to close the liquid inlet, and makes the second power generation unit move away from the first power generation unit to generate a second electrical signal.

[0005] In the above embodiment, the friction sensing unit is combined with the piezoelectric vibrator. The piezoelectric vibrator is used as a switch. It can control the liquid flow time by controlling the deformation of the piezoelectric vibrator, and can also drive the friction sensing unit to work through the piezoelectric vibrator. Under the premise of not affecting the normal operation of the piezoelectric vibrator, by monitoring the electrical signal generated by the friction sensing unit, the voltage amplitude change and the number of frequency pulses are obtained, thereby obtaining the actual response time of the piezoelectric vibrator switch, realizing the function of real-time flow monitoring, and improving the accuracy of flow monitoring to the microliter level, thereby improving the accuracy of flow monitoring. In addition, when the piezoelectric vibrator fails, the friction sensing unit will not generate an electrical signal. By monitoring the changes in the electrical signal generated by the friction sensing unit, it is possible to monitor whether the piezoelectric vibrator is abnormal, such as whether it is damaged. It is convenient for users to maintain the equipment in time. The friction electric self-sensing piezoelectric microvalve of the present application has a simple structure and a small size, and can be used in scenes such as drug injection, biomedical mixing and proportioning.

[0006] In one embodiment, the first power generation unit and the second power generation unit are separated by a preset distance, and the preset distance is 1 mm.

[0007] In one embodiment, the first power generation unit includes a stacked nylon film layer and a first electrode layer, and the first electrode layer is located between the shell and the nylon film layer.

[0008] In one embodiment, the second power generation unit includes an FEP film layer, and the EFP film layer is fixedly connected to the surface of the piezoelectric vibrator facing the first power generation unit.

[0009] In one embodiment, the piezoelectric vibrator includes a stacked ceramic layer and a second electrode layer, and the second power generation unit is installed on a side of the ceramic layer away from the second electrode layer.

[0010] In one embodiment, the second power generation unit includes an EFP film layer and an insulating adhesive layer, and the insulating adhesive layer is disposed between the EFP film layer and the piezoelectric vibrator.

[0011] In one embodiment, the orthographic projection of the first power generation unit on the second power generation unit is completely located within the second power generation unit.

[0012] In one embodiment, the shell includes a body and a cover, the cover is snapped with the body to form a receiving cavity, the first power generation unit is mounted on the cover, and the piezoelectric vibrator is mounted on the body.

[0013] In one embodiment, the triboelectric self-sensing piezoelectric microvalve also includes a first sealing ring and a second sealing ring, the main body is provided with a first mounting groove, the first sealing ring is installed in the first mounting groove, the cover is provided with a second mounting groove, the second sealing ring is installed in the second mounting groove, and the first sealing ring and the second sealing ring are coaxially arranged.

[0014] In one embodiment, the triboelectric self-sensing piezoelectric microvalve also includes a flexible gasket, which is fixedly mounted on the side of the piezoelectric vibrator facing the liquid inlet; when the piezoelectric vibrator is deformed to open the liquid inlet, the flexible gasket moves away from the liquid inlet with the piezoelectric vibrator; or, when the piezoelectric vibrator is deformed to close the liquid inlet, the flexible gasket fits against the liquid inlet.

[0015] On the other hand, an embodiment of the present application also provides a flow monitoring method, which is applied to the above-mentioned triboelectric self-sensing piezoelectric microvalve, and the flow monitoring method includes: sending a driving signal to the piezoelectric vibrator to cause the piezoelectric vibrator to deform to open or close the liquid inlet; adjusting the deformation amount of the piezoelectric vibrator by controlling the voltage of the driving signal to control the flow rate v of the liquid; real-time monitoring of the first electrical signal and the second electrical signal generated by the friction sensing unit to obtain the time t1 when the piezoelectric vibrator actually opens the liquid inlet; and obtaining the liquid flow through the triboelectric self-sensing piezoelectric microvalve based on the actual opening time t1 of the liquid inlet and the flow rate v of the liquid.

[0016] In one embodiment, sending a driving signal to the piezoelectric vibrator causes the piezoelectric vibrator to deform to open or close the liquid inlet, including: sending a first square wave signal to the piezoelectric vibrator, and controlling the time t2 for the piezoelectric vibrator to open the liquid inlet by controlling the duty cycle of the first square wave signal.

[0017] In one embodiment, the first electrical signal and the second electrical signal generated by the friction sensing unit are monitored in real time to obtain the time t1 when the piezoelectric vibrator actually opens the liquid inlet, including: converting the first electrical signal and the second electrical signal into a second square wave signal, and obtaining the time t1 when the piezoelectric vibrator actually opens the liquid inlet through the duty cycle of the second square wave signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the structure of a triboelectric self-sensing piezoelectric microvalve provided in one embodiment of the present application;

[0019] Figure 2 An exploded view of a first power generation unit and a cover portion provided for one embodiment of the present application;

[0020] Figure 3 An exploded diagram of a second power generation unit and a piezoelectric vibrator provided in accordance with an embodiment of the present application;

[0021] Figure 4 An exploded diagram of a triboelectric self-sensing piezoelectric microvalve provided for one embodiment of the present application;

[0022] Figure 5 A top view of a body provided for one embodiment of the present application;

[0023] Figure 6 A flow chart of a flow monitoring method provided for one embodiment of the present application.

[0024] Reference numerals:

[0025] 1-shell; 2-piezoelectric vibrator; 3-friction sensor unit; 11-liquid inlet; 12-liquid outlet; 31-first power generation unit; 32-second power generation unit; 311-nylon film layer; 312-first electrode layer; 321-FEP film layer; 322-insulating rubber layer; 21-ceramic layer; 22-second electrode layer; 101-cover; 102-body; 1011-through hole; 4-first sealing ring; 5-second sealing ring; 1021-first mounting groove; 1012-second mounting groove; 13-first chamber; 14-second chamber; 6-flexible gasket; 00-screw. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the accompanying drawings.

[0027] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting of the present application. As used in the specification and appended claims of the present application, the singular expressions "a", "an", "said", "above", "the" and "this" are intended to also include expressions such as "one or more", unless there is a clear contrary indication in the context.

[0028] References to "one embodiment" or "a specific embodiment" in this specification mean that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. The terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0029] In the relevant technology, piezoelectric ceramics are a material that can convert electrical energy and mechanical energy into each other, and have piezoelectric effect and inverse piezoelectric effect. When voltage is applied, it will generate mechanical vibration; conversely, when mechanical pressure is applied, it will generate voltage. Piezoelectric ceramics have the advantages of high sensitivity, high precision, high stability, etc., and are widely used in sensors, drivers, vibrators and other fields.

[0030] A square wave is a periodic waveform at a specific frequency, and its waveform changes suddenly between the positive and negative half cycles of equal amplitude. Square waves have the characteristics of periodicity, high frequency, and high precision, and are widely used in digital circuits, communication systems, control systems, and other fields.

[0031] Combining piezoelectric ceramics with square waves can use square wave signals as driving signals to make the piezoelectric ceramics perform periodic reversal switching actions, thereby achieving more accurate measurement and control. However, in the process of controlling piezoelectric ceramics, although the piezoelectric ceramics can be controlled to perform switching actions by square wave driving signals, the actual deformation time of the piezoelectric ceramics may deviate from the deformation time of the driving signal due to environmental factors such as medium viscosity and temperature, resulting in errors in flow monitoring.

[0032] To solve the above problems, the present application provides a triboelectric self-sensing piezoelectric microvalve and flow monitoring method that monitors flow by combining triboelectricity and piezoelectricity, so as to solve the technical problem of low accuracy in monitoring flow using liquid flow valves.

[0033] Figure 1 A schematic diagram of the structure of a triboelectric self-sensing piezoelectric microvalve provided in one embodiment of the present application. Figure 1As shown, a triboelectric self-sensing piezoelectric microvalve provided in an embodiment of the present application is installed in a fluid pipeline, and the triboelectric self-sensing piezoelectric microvalve includes a housing 1, a piezoelectric vibrator 2 and a friction sensing unit 3. Among them, the housing 1 has a liquid inlet 11 and a liquid outlet 12, and the liquid in the pipeline can enter the housing 1 from the liquid inlet 11 and flow out of the housing 1 from the liquid outlet 12. The piezoelectric vibrator 2 and the friction sensing unit 3 are both arranged in the housing 1. The friction sensing unit 3 includes a first power generation unit 31 and a second power generation unit 32 arranged opposite to each other, the first power generation unit 31 is fixedly connected to the inner wall of the housing 1, and the second power generation unit 32 is fixedly connected to the surface of the piezoelectric vibrator 2 facing the first power generation unit 31. The piezoelectric vibrator 2 is used to drive the second power generation unit 32 to contact or move away from the first power generation unit 31. The piezoelectric vibrator 2 is arranged at the liquid inlet 11, and the piezoelectric vibrator 2 receives an externally applied driving voltage to generate deformation. The deformation includes two actions, one is bending to the side away from the liquid inlet 11, and the other is bending to the side of the liquid inlet 11. When the piezoelectric vibrator 2 bends in a direction away from the liquid inlet 11, a gap is generated between the piezoelectric vibrator 2 and the liquid inlet 11, the liquid inlet 11 is opened, and the liquid in the fluid pipeline can enter the shell 1 and then flow out of the shell 1 from the liquid outlet 12. When the piezoelectric vibrator 2 bends toward the side of the liquid inlet 11, the piezoelectric vibrator 2 contacts the liquid inlet 11, closing the liquid inlet 11. During the deformation process, when the piezoelectric vibrator 2 bends in a direction away from the liquid inlet 11, it can drive the second power generation unit 32 to approach and contact the first power generation unit 31. The gap between the first power generation unit 31 and the second power generation unit 32 gradually decreases until they contact, friction electrification and electrostatic coupling effects occur, and a first electrical signal is generated; when the piezoelectric vibrator 2 bends toward the side of the liquid inlet 11, it drives the second power generation unit 32 away from the first power generation unit 31, and the gap between the first power generation unit 31 and the second power generation unit 32 gradually increases, the potential changes, and a second electrical signal is generated. During the continuous operation, the piezoelectric vibrator 2 will repeatedly open and close the liquid inlet 11, and at the same time, the friction sensor unit 3 outputs an alternating current pulse signal to form a square wave.

[0034] In the above embodiment, the friction sensing unit 3 can be specifically a friction nanogenerator. Based on the friction electrification and electrostatic coupling effects, the friction nanogenerator can convert mechanical energy into electrical signals to realize intelligent sensing. The two power generation units of the friction sensing unit 3 generate electrical signals during the contact and separation process, and the voltage amplitude change and the number of frequency pulses can be obtained through the electrical signals. The friction sensing unit 3 is combined with the piezoelectric vibrator 2, and the piezoelectric vibrator 2 is used as a switch. It can control the flow time of the liquid by controlling the deformation of the piezoelectric vibrator 2, and can also drive the friction sensing unit 3 to work through the piezoelectric vibrator 2. Under the premise of not affecting the normal operation of the piezoelectric vibrator 2, by monitoring the electrical signal generated by the friction sensing unit 3, the voltage amplitude change and the number of frequency pulses are obtained, thereby obtaining the actual response time of the piezoelectric vibrator 2 switch, realizing the function of real-time flow monitoring, and improving the accuracy of flow monitoring to the microliter level, thereby improving the accuracy of flow monitoring.

[0035] In addition, when the piezoelectric vibrator 2 fails, the friction sensing unit 3 will not generate an electrical signal. By monitoring the changes in the electrical signal generated by the friction sensing unit 3, it is possible to monitor whether the piezoelectric vibrator 2 is abnormal, such as whether it is damaged. This is convenient for users to maintain the equipment in a timely manner. The friction electric self-sensing piezoelectric microvalve of the present application has a simple structure and a small size, and can be used in scenarios such as drug injection, biomedical mixing and proportioning.

[0036] The core power generation principle of the friction nanogenerator (TENG) is derived from the friction between the surfaces of objects of different materials, which can be specifically divided into four basic forms: vertical contact separation, horizontal sliding, single electrode, and independent layer. The friction sensing unit 3 of the present application adopts the form of single electrode power generation. The friction nanogenerator is mainly composed of two basic components: friction material and electrode. The friction material is the core part of the friction nanogenerator, usually composed of two materials with different triboelectric properties. When the two materials are in contact with each other, charge separation will occur due to the transfer of electrons. When the two materials are separated, an electric potential difference will be generated, and the charge will be transferred to the external circuit through the electrode to form an electric current. The specific structure and material of the friction sensing unit 3 of the present application are introduced below:

[0037] Figure 2 An exploded view of a first power generation unit and a cover portion provided for one embodiment of the present application, Figure 3 An exploded diagram of a second power generation unit and a piezoelectric vibrator provided in one embodiment of the present application. Figure 2 and Figure 3As shown, in one embodiment, the first power generation unit 31 is a thin structure, including a stacked nylon film layer 311 and a first electrode layer 312, and the first electrode layer 312 is located between the shell 1 and the nylon film layer 311. The first electrode layer 312 can specifically be a copper electrode layer. The second power generation unit 32 is also a thin structure, including an FEP film layer 321. The EFP film layer is fixedly connected to the surface of the piezoelectric vibrator 2 facing the first power generation unit 31. Specifically, when installing the FEP film layer 321, it can be bonded to the piezoelectric vibrator 2 through the insulating adhesive layer 322. The insulating adhesive layer 322 is located between the piezoelectric vibrator 2 and the FEP film layer 321. FEP film (fluoroethylene propylene film) is a material copolymerized by tetrafluoroethylene and hexafluoropropylene.

[0038] The nylon film layer 311 and the FEP film layer 321 are two material layers with different triboelectric properties. A potential difference will be generated during the process of contact and separation. The charge is transferred to the external circuit through the first electrode layer 312 to form an electrical signal. The flow rate is monitored by monitoring the electrical signal.

[0039] In one embodiment, along a direction perpendicular to the piezoelectric vibrator 2 , the orthographic projection of the first electrode layer 312 on the nylon membrane layer 311 completely overlaps with the nylon membrane layer 311 .

[0040] In one embodiment, the first power generation unit 31 and the second power generation unit 32 are separated by a preset distance when not working, and the preset distance can specifically be 1 mm. The spacing between the first power generation unit 31 and the second power generation unit 32 is set to 1 mm, which can effectively reduce the volume of the friction sensing unit 3, thereby reducing the volume of the friction electric self-sensing piezoelectric microvalve, so that it can be applied to some miniature scenes. In addition, the spacing can enable the friction sensing unit 3 to output a stable current to improve the monitoring accuracy. It can also reduce the damage of friction to the film layer when the friction sensing unit 3 is not working, thereby increasing the service life of the nylon film layer 311 and the FEP film layer 321.

[0041] In one embodiment, the piezoelectric vibrator 2 is also a thin structure, which can be deformed and bent under the action of the reverse piezoelectric effect when receiving a voltage signal. It includes a stacked ceramic layer 21 and a second electrode layer 22, and the second power generation unit 32 is installed on the side of the ceramic layer 21 away from the second electrode layer 22, that is, the FEP film is bonded to the surface of the ceramic layer 21. The second electrode layer 22 can be a copper electrode layer.

[0042] The above stacking directions are all perpendicular to the piezoelectric vibrator 2 .

[0043] To prevent the electric charge on the ceramic layer 21 from being transferred to the EFP film layer 321, thereby affecting the electric signal generated by the monitoring friction sensor unit 3. In one embodiment, the second power generation unit 32 further includes an insulating rubber layer 322, which is disposed between the EFP film layer 321 and the ceramic layer 21 of the piezoelectric vibrator 2. The insulating rubber layer 322 can isolate the EFP film layer 321 from the ceramic layer 21, thereby preventing the electric charge on the ceramic layer 21 from being transferred to the EFP film layer, thereby causing monitoring errors.

[0044] In one embodiment, the insulating rubber layer 322 completely covers the ceramic layer 21 in the orthographic projection of the piezoelectric vibrator 2, so the EFP film layer 321 or the nylon film layer 311 cannot contact the ceramic layer 21 at all. This can reduce the influence of the piezoelectric vibrator 2 on the friction sensor unit 3, thereby improving the accuracy of the electrical signal generated by the friction sensor unit 3.

[0045] In one embodiment, the insulating adhesive layer 322 and the EFP film layer 321 have the same shape and area, and are bonded together to facilitate the assembly of the second power generation unit 32. The nylon film layer 311 and the first electrode layer 312 have the same shape and area, and are bonded together to facilitate the assembly of the first power generation unit 31.

[0046] In one embodiment, the orthographic projection of the first power generation unit 31 on the second power generation unit 32 is completely located inside the second power generation unit.

[0047] The cross-section and area of ​​the first power generation unit 31 and the second power generation unit 32 can be arranged in the following situations:

[0048] In one embodiment, the cross-sections and areas of the first power generation unit 31, the second power generation unit 32 and the ceramic layer 21 are exactly the same, and are all circular or square. Along the stacking direction, the orthographic projection of the first power generation unit 31 on the second power generation unit 32 completely overlaps with the second power generation unit 32, and the orthographic projection of the second power generation unit 32 on the ceramic layer 21 completely overlaps with the ceramic layer 21. When specifically assembling, the first power generation unit 31, the second power generation unit 32 and the ceramic layer 21 can be coaxially arranged. The second power generation unit 32 overlaps with the ceramic layer 21, and the first power generation unit 31 and the second power generation unit 32 overlap when in contact.

[0049] In the above embodiment, the first power generation unit 31 and the second power generation unit 32 completely overlap when in contact, which is an ideal state for assembly. However, in the actual assembly process, affected by the assembly process, the first power generation unit 31 and the second power generation unit 32 have a certain assembly error, resulting in the first power generation unit 31 and the second power generation unit 32 not being able to completely overlap when in contact. Therefore, the area of ​​the second power generation unit 32 can also be set to be larger than the area of ​​the first power generation unit 31, so that the second power generation unit 32 isolates the piezoelectric vibrator 2 from the first power generation unit 31, thereby reducing the influence of the piezoelectric vibrator 2 on the friction sensor unit 3.

[0050] In another embodiment, the cross-sectional shape of the first power generation unit 31 and the second power generation unit 32 is the same, the area of ​​the second power generation unit 32 is larger than the area of ​​the first power generation unit 31 , and the orthographic projection of the first power generation unit 31 on the second power generation unit 32 is completely located in the second power generation unit 32 .

[0051] Alternatively, in another embodiment, the cross section of the first power generation unit 31 is circular, the cross section of the second power generation unit 32 is square, the area of ​​the second power generation unit 32 is larger than the area of ​​the first power generation unit 31, and the orthographic projection of the first power generation unit 31 on the second power generation unit 32 is completely located in the second power generation unit 32. The ceramic layer 21 is circular, and the second power generation unit 32 is inscribed in the ceramic layer 21.

[0052] Alternatively, in another embodiment, the cross section of the first power generation unit 31 is square, and the cross section of the second power generation unit 32 is circular. The area of ​​the second power generation unit 32 is larger than that of the first power generation unit 31, and the orthographic projection of the first power generation unit 31 on the second power generation unit 32 is completely located in the second power generation unit 32.

[0053] The above-mentioned area refers to the area of ​​each surface of the first power generation unit 31 and the second power generation unit 32 on the side in contact with each other.

[0054] Figure 4 An exploded diagram of a triboelectric self-sensing piezoelectric microvalve provided in one embodiment of the present application is shown in FIG. Figure 4 As shown, in one embodiment, the housing 1 includes a body 102 and a cover 101, the cover 101 and the body 102 are buckled together to form a receiving cavity, the first power generation unit 31 is installed on the cover 101, and the piezoelectric vibrator 2 is installed on the body 102. The cover 101 and the body 102 are respectively provided with corresponding threaded holes, and the cover 101 and the body 102 can be connected and fixed by screws 00.

[0055] In one embodiment, the cover 101 is provided with a through hole 1011, and the through hole 1011 does not overlap with the first power generation unit 31. The through hole 1011 can be used for the cable connected to the friction sensor unit 3 and the piezoelectric vibrator 2 to pass through.

[0056] In one embodiment, the housing 1 may be a cylinder, a quadrangular prism or a polygonal prism.

[0057] Figure 5 A top view of a body provided for one embodiment of the present application, combined with Figure 1 , Figure 2 , Figure 4 and Figure 5 In one embodiment, the triboelectric self-sensing piezoelectric microvalve further includes a first sealing ring 4 and a second sealing ring 5. A first mounting groove 1021 is provided at the bottom of the body 102, and the first sealing ring 4 is installed in the first mounting groove 1021. The cover 101 is provided with a second mounting groove 1012, and the second mounting groove 1012 is located on the peripheral side of the first power generation unit 31. The second sealing ring 5 is installed in the second mounting groove 1012, and the first sealing ring 4 and the second sealing ring 5 can be coaxially arranged. The piezoelectric vibrator 2 is located between the first sealing ring 4 and the second sealing ring 5. After the cover 101 is buckled with the body 102, the first sealing ring 4 and the second sealing ring 5 can press and fix the piezoelectric vibrator 2. Since the first sealing ring 4 and the second sealing ring 5 are coaxially arranged, the piezoelectric vibrator 2 can be subjected to even force.

[0058] The piezoelectric vibrator 2 divides the shell 1 into a first chamber 13 and a second chamber 14. The first sealing ring 4, the piezoelectric vibrator 2 and the bottom of the body 102 enclose the first chamber 13, and the first chamber 13 is a closed chamber. The liquid inlet 11 and the liquid outlet 12 are both located at the bottom of the shell 1. When the piezoelectric vibrator 2 opens the liquid inlet 11, the liquid enters the first chamber 13 from the liquid inlet 11. When the first chamber 13 is full, the liquid flows out of the first chamber 13 from the liquid outlet 12. The cover 101, the second sealing ring 5 and the piezoelectric vibrator 2 enclose the second chamber 14, which is completely isolated from the first chamber 13, and the liquid will not enter the second chamber 14 to cause a short circuit.

[0059] Please continue to refer to Figure 1 In one embodiment, the triboelectric self-sensing piezoelectric microvalve further includes a flexible gasket 6, which is fixedly mounted on the side of the piezoelectric vibrator 2 facing the liquid inlet 11. When the piezoelectric vibrator 2 is deformed to open the liquid inlet 11, the flexible gasket 6 moves away from the liquid inlet 11 with the piezoelectric vibrator 2. Alternatively, when the piezoelectric vibrator 2 is deformed to close the liquid inlet 11 under the control of the controller, the flexible gasket 6 fits the liquid inlet 11. At this time, the flexible gasket 6 is deformed by the pressure of the liquid inlet 11 and the piezoelectric vibrator 2 to block the liquid inlet 11, thereby improving the sealing performance of the first chamber 13.

[0060] In one embodiment, the above-mentioned triboelectric self-sensing piezoelectric microvalve may also include a controller, a data collector, a data processor and a display panel (not shown in the figure). The controller is used to send a driving signal to the piezoelectric vibrator 2, and the data collector is used to collect the first electrical signal and the second electrical signal emitted by the friction sensing unit 3. The data processor is used to analyze and convert the first electrical signal and the second electrical signal to obtain flow data, and send the flow data to the display panel for display. The above-mentioned controller, data collector, data processor and display panel are all conventional modules, and their specific structures are not repeated in this application.

[0061] Figure 6 A flow chart of a flow monitoring method provided by an embodiment of the present application is as follows: Figure 6 As shown, an embodiment of the present application further provides a flow monitoring method, which is applied to the triboelectric self-sensing piezoelectric microvalve in any of the above embodiments, and the flow monitoring method includes the following steps:

[0062] S1: The controller sends a driving signal to the piezoelectric vibrator 2, causing the piezoelectric vibrator 2 to deform to open or close the liquid inlet 11. The piezoelectric vibrator 2 serves as a switch of the triboelectric self-sensing piezoelectric microvalve, and can control the inflow of liquid.

[0063] Specifically, when the piezoelectric vibrator 2 does not receive a driving signal, it is in a non-working state, and the friction sensing unit 3 does not generate an electrical signal. When the driving signal is input, the piezoelectric vibrator 2 bends and deforms to the side away from the liquid inlet 11, and the flexible gasket 6 moves with the piezoelectric vibrator 2. At this time, the liquid inlet 11 is in an open state, and the liquid begins to flow in. The liquid enters the first chamber 13 from the liquid inlet 11, and flows out from the liquid outlet 12 after filling the first chamber 13. At this time, the gap between the FEP film layer 321 and the nylon film layer 311 becomes smaller until they contact, and friction charging and electrostatic coupling effects occur, generating a first electrical signal, and then the piezoelectric vibrator 2 is in a continuously open state. After the time t2 when the piezoelectric vibrator 2 opens the liquid inlet 11 ends, the piezoelectric vibrator 2 bends to the side of the liquid inlet 11, the flexible gasket 6 blocks the liquid inlet 11, and the liquid stops flowing in. At this time, the liquid inlet 11 is in a closed state. At this time, the gap between the FEP film layer 321 and the nylon film layer 311 becomes larger, the potential changes to generate a second electrical signal, and then the piezoelectric vibrator 2 is in a continuously closed state, completing a cycle. During the continuous operation, the piezoelectric vibrator 2 will cycle through the two actions of opening and closing. When the driving signal stops, the piezoelectric vibrator 2 returns to the non-deformed state when it is not working.

[0064] In step S1 , a driving signal is sent to the piezoelectric vibrator 2 to cause the piezoelectric vibrator 2 to deform to open or close the liquid inlet 11 , including: sending a first square wave signal to the piezoelectric vibrator 2 , and controlling the time t2 for the piezoelectric vibrator 2 to open the liquid inlet 11 by the duty cycle of the first square wave signal.

[0065] A square wave is a non-sinusoidal waveform. A square wave signal is a signal in which the voltage or current switches rapidly between two specific levels in each cycle, usually between a maximum value and a minimum value. The duty cycle of a square wave signal refers to the ratio of the time that the signal is at a high level to the entire cycle time in one cycle. Specifically, the duty cycle refers to the ratio of the time that the high level occupies within one cycle. The duty cycle of a square wave is 50%, which means that in a complete signal cycle, the signal is at a high level half of the time and at a low level the other half of the time. In the present application, the width of the duty cycle in the waveform of the first square wave signal is the opening time t2 of the liquid inlet 11. The opening time t2 of the liquid inlet 11 can be controlled by adjusting the duty cycle of the first square wave signal.

[0066] S2: The deformation of the piezoelectric vibrator 2 is adjusted by controlling the voltage of the driving signal to control the flow rate v of the liquid.

[0067] Specifically, the driving signal can be a voltage signal, and the piezoelectric vibrator 2 can change the deformation according to different voltage signals. For example, increasing the voltage increases the deformation of the piezoelectric vibrator 2, thereby increasing the valve opening, and the corresponding liquid flow rate per unit time will also increase (i.e., the flow rate increases). In other words, the flow rate can be controlled by the driving signal, and the flow rate v under a fixed voltage is a fixed value, and the flow rate is a uniform flow.

[0068] S3: Real-time monitoring of the first electrical signal and the second electrical signal generated by the friction sensor unit 3 to obtain the time t1 when the piezoelectric vibrator 2 actually opens the liquid inlet 11

[0069] Since there is a deviation between the controlled opening time t2 and the actual opening time t1 of the piezoelectric vibrator 2 , a more accurate actual opening time t1 of the piezoelectric vibrator 2 can be obtained by monitoring the electrical signal of the friction sensor unit 3 , thereby improving the flow monitoring accuracy.

[0070] In step S3, the first electrical signal and the second electrical signal generated by the friction sensing unit 3 are monitored in real time to obtain the time t1 when the piezoelectric vibrator 2 actually opens the liquid inlet 11, including: a data collector collects the first electrical signal and the second electrical signal, generates a second square wave signal after processing by a data processor, and obtains the time t1 when the piezoelectric vibrator 2 actually opens the liquid inlet 11 after responding through the second square wave signal.

[0071] S4: The liquid flow Q passing through the triboelectric self-sensing piezoelectric microvalve is obtained according to the actual opening time t1 of the liquid inlet 11 and the liquid flow rate v. Q=t1×v.

[0072] The triboelectric self-sensing piezoelectric microvalve and flow monitoring method of the present application combines piezoelectric ceramics with triboelectric nanogenerators, and proposes a new triboelectric self-sensing piezoelectric microvalve, which can realize self-sensing flow monitoring. The friction sensing unit 3 is integrated with the piezoelectric vibrator 2, which improves the space utilization rate, is conducive to the miniaturization and integration of the device, and the flow monitoring accuracy can reach the microliter level.

[0073] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A triboelectric self-sensing piezoelectric microvalve, characterized in that: It includes a shell, a piezoelectric vibrator and a friction sensor unit, wherein: The shell has a liquid inlet and a liquid outlet, the piezoelectric vibrator and the friction sensor unit are arranged in the shell, and the piezoelectric vibrator is arranged at the liquid inlet; The friction sensing unit comprises a first power generation unit and a second power generation unit which are arranged opposite to each other, wherein the first power generation unit is fixedly connected to the inner wall of the housing, and the second power generation unit is fixedly connected to the piezoelectric vibrator, and the piezoelectric vibrator is used to drive the second power generation unit to contact or move away from the first power generation unit; The piezoelectric vibrator is deformed under the action of the driving voltage to open the liquid inlet, and makes the second power generation unit contact the first power generation unit to generate a first electrical signal; or, the piezoelectric vibrator is deformed under the control of the driving voltage to close the liquid inlet, and makes the second power generation unit move away from the first power generation unit to generate a second electrical signal.

2. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The first power generation unit and the second power generation unit are spaced apart by a preset distance, and the preset distance is 1 mm.

3. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The first power generation unit includes a nylon film layer and a first electrode layer which are stacked, and the first electrode layer is located between the shell and the nylon film layer.

4. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The second power generation unit includes an FEP film layer, and the EFP film layer is fixedly connected to a surface of the piezoelectric vibrator facing the first power generation unit.

5. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The piezoelectric vibrator includes a stacked ceramic layer and a second electrode layer, and the second power generation unit is installed on a side of the ceramic layer away from the second electrode layer.

6. The triboelectric self-sensing piezoelectric microvalve according to claim 5, characterized in that: The second power generation unit includes an EFP film layer and an insulating adhesive layer, and the insulating adhesive layer is arranged between the EFP film layer and the piezoelectric vibrator.

7. The triboelectric self-sensing piezoelectric microvalve according to claim 6, characterized in that: The orthographic projection of the first power generation unit on the second power generation unit is completely located in the second power generation unit.

8. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The shell includes a body and a cover, the cover is buckled with the body to form a receiving cavity, the first power generation unit is installed on the cover, and the piezoelectric vibrator is installed on the body.

9. The triboelectric self-sensing piezoelectric microvalve according to claim 8, characterized in that: The triboelectric self-sensing piezoelectric microvalve also includes a first sealing ring and a second sealing ring. The main body is provided with a first mounting groove, and the first sealing ring is installed in the first mounting groove. The cover is provided with a second mounting groove, and the second sealing ring is installed in the second mounting groove. The first sealing ring and the second sealing ring are coaxially arranged.

10. The triboelectric self-sensing piezoelectric microvalve according to claim 1, characterized in that: The triboelectric self-sensing piezoelectric microvalve further comprises a flexible gasket, which is fixedly mounted on a side of the piezoelectric vibrator facing the liquid inlet; When the piezoelectric vibrator is deformed to open the liquid inlet, the flexible gasket moves away from the liquid inlet along with the piezoelectric vibrator; or, when the piezoelectric vibrator is deformed to close the liquid inlet, the flexible gasket fits against the liquid inlet.

11. A flow monitoring method, applied to the triboelectric self-sensing piezoelectric microvalve according to any one of claims 1 to 10, characterized in that: include: Sending a driving signal to the piezoelectric vibrator to cause the piezoelectric vibrator to deform so as to open or close the liquid inlet; The deformation of the piezoelectric vibrator is adjusted by controlling the voltage of the driving signal to control the flow rate v of the liquid; the first electrical signal and the second electrical signal generated by the friction sensor unit are monitored in real time to obtain the time t1 when the piezoelectric vibrator actually opens the liquid inlet; The liquid flow rate passing through the triboelectric self-sensing piezoelectric microvalve is obtained according to the actual opening time t1 of the liquid inlet and the flow rate v of the liquid.

12. The flow monitoring method according to claim 11, characterized in that: Sending a driving signal to the piezoelectric vibrator causes the piezoelectric vibrator to deform to open or close the liquid inlet, including: sending a first square wave signal to the piezoelectric vibrator, and controlling the time t2 when the piezoelectric vibrator opens the liquid inlet through the duty cycle of the first square wave signal.

13. The flow monitoring method according to claim 11, characterized in that: The first electrical signal and the second electrical signal generated by the friction sensing unit are monitored in real time to obtain the time t1 when the piezoelectric vibrator actually opens the liquid inlet, including: converting the first electrical signal and the second electrical signal into a second square wave signal, and obtaining the time t1 when the piezoelectric vibrator actually opens the liquid inlet through the duty cycle of the second square wave signal.

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