Structure of miniature flexible piezoelectric thick film generator and power generation device

Abstract

The utility model belongs to the field of miniature piezoelectric generators, and relates to a structure of a miniature flexible piezoelectric thick film generator and a power generation device, the piezoelectric thick film generator is formed by superposing three layers of sheet structures, the lower layer is a rectangular flexible conductive substrate, one side of the flexible conductive substrate extends outwards to form a long-strip-shaped cantilever beam structure, and the other side of the flexible conductive substrate extends outwards to form a long-strip-shaped cantilever beam structure. The middle layer is a PZT piezoelectric thick film, the upper layer is an upper electrode, the upper layer, the middle layer and the lower layer are the same in shape, and the areas are sequentially decreased from bottom to top in proportion. According to the utility model, the PZT is directly printed on the flexible conductive substrate through a co-firing connection method and an electric jet printing technology, so that the absorption deformation of the adhesive layer is effectively avoided, the charge transfer is promoted to be more direct, and the problem of device failure caused by the increase and change of the adhesive layer is avoided. According to the utility model, the electric jet printing technology is utilized, the minimum size of the manufactured generator is 50 [mu] m-2cm, and the generator can adapt to environmental changes, can be normally used in various complex environments, and is low in manufacturing cost and wide in application.

Description

Technical Field

[0001] The utility model belongs to the field of micro piezoelectric generators. Background Art

[0002] Piezoelectric generators use the piezoelectric effect to convert mechanical energy into electrical energy. They do not require an external power supply and have the characteristics of high energy density, simple structure, and strong environmental adaptability. However, due to the problem of low power generation, piezoelectric generators are difficult to meet the energy requirements of micro devices such as wireless sensors and radio frequency identification systems. Piezoelectric bulk materials are mainly hard and brittle, with small deformation; thin films are highly flexible, but their piezoelectric coefficient is low, resulting in low power generation. To address this problem, a 10μm thick film is proposed, which takes into account both piezoelectricity and large deformation, and a method for manufacturing a piezoelectric constant flexible deformation generator is proposed.

[0003] Although continuous piezoelectric film layers have excellent functions, piezoelectric microstructures or arrays with discrete features can effectively alleviate the clamping effect and heat diffusion of rigid substrates, and can effectively increase deformation and stress release, thereby improving the functionality and reliability of piezoelectric devices. For example, MEMS piezoelectric deformable mirrors, piezoelectric micromotors, ultrasonic scanning transducers and other devices all require such piezoelectric microstructures. However, existing microstructure manufacturing methods still have some challenges, including complex microstructure preparation process, damage introduced during the preparation process, and limited manufacturing accuracy.

[0004] Many researchers have studied various techniques for depositing piezoelectric thick films and have shown considerable capabilities. For example, methods such as tape casting and screen printing are usually suitable for preparing continuous film layers, and the single-layer film layer is above 20 to 30 μm, with low resolution. The fabrication of piezoelectric thick film microstructures usually involves photolithography and etching processes to make sacrificial layers or mask layers, or patterning piezoelectric thick film microstructures by laser processing, micromachining, wet etching, or dry etching. For dry etching, the reaction of etching gases will form extremely difficult-to-remove compounds on the surface of the piezoelectric thick film, which will hinder the smooth progress of etching and affect the vertical accuracy of the sidewalls. In addition, this etching method not only etches the film layer, but also etches the electrodes and substrate, causing damage to other components. In addition, there will be many high-energy ions during the dry etching process, which will also destroy the crystal structure formed inside the perovskite structure during the bombardment process, resulting in surface atomic displacement and vacancies. Utility Model Content

[0005] In order to solve the problems of the prior art, the utility model provides a structure and a power generation device of a piezoelectric thick film generator that takes into account high voltage electrical constant, large flexibility and deformation. The piezoelectric material is made to have a thickness of less than ten microns, so that it not only takes into account the advantages of high voltage electrical properties of bulk materials, but also has the advantages of large flexibility and deformation of thin films, which effectively improves the power generation. The higher resolution of electrospray printing can realize the printing and manufacturing of thick film elements of arbitrary shapes, and print and prepare piezoelectric thick films of less than 10μm on flexible substrates, taking into account flexibility and high energy density, forming a flexible generator, reducing the volume and making it lighter. A certain flexibility is used to achieve its larger flexible deformation, thereby generating greater energy and timely release of vibration stress, ensuring high power generation and reliability of the power generation device, and its deformation ability is stronger and its flexibility is not easily destroyed. The generator can adapt to environmental changes and can work normally in various complex environments.

[0006] The technical solution adopted by the utility model is:

[0007] The piezoelectric thick film generator of the utility model is composed of a three-layer structure, wherein the lower layer is a rectangular flexible conductive substrate 1, one side of the flexible conductive substrate 1 extends outward to form a cantilever beam structure, the middle layer is a PZT piezoelectric thick film 2, and the upper layer is an upper electrode 3. The upper, middle and lower three-layer structures have the same shape and their areas decrease in proportion from bottom to top. Since the PZT material contains the same elements as those in the flexible conductive substrate 1, after the PZT material is jet-printed on the flexible conductive substrate 1, the same elements between the two-layer structures are covalently bonded to form an integrated structure.

[0008] Its manufacturing method is that a high-voltage power supply 25 is connected to a spray needle 30 through a wire ⅹⅲ-26, a micro-energy injector 34 is connected to an injection tube 31, a PZT material is contained in the injection tube 31, the injection tube 31 is connected to the spray needle 30, and the PZT material forms a Taylor cone 29 under the action of the high-voltage power supply 25 and then forms a fine jet 28, wherein the PZT piezoelectric thick film 2 is sprayed, the jet base 27 is grounded, one end of the upper computer 33 chassis is connected to the jet base 27 through a wire ⅹⅴ-36, and the other end of the upper computer 33 chassis is connected to a micro camera 32 through a wire ⅹⅳ-35.

[0009] After the piezoelectric thick film generator is placed in the muffle furnace 37 for co-firing, the muffle furnace 37 is equipped with a temperature setting key 38 and a display panel 39. After co-firing, the piezoelectric thick film generator is placed on the polarization table 40, and the polarization table 40 is equipped with a polarization table knob 41. The wire ⅹⅵ-42 connects the upper electrode with the positive pole of the polarization power supply 44, and the wire ⅹⅶ-43 connects the flexible conductive substrate 1 with the negative pole of the polarization power supply 44.

[0010] This piezoelectric thick film generator is fixed on the pillar 5, and the wind blade 8 is suspended on the lower end of the tail of the cantilever beam extending from one side of the flexible conductive substrate 1 through the flexible connecting rod 7. The pillar 5 is fixed on the base 4, and the conductive silver paste ⅰ-6-1 is dripped on the upper electrode 3. One end of the wire ⅲ-11 is connected to the diode ⅰ-19, and the other end of the diode ⅰ-19 is connected to the wire ⅴ-13 to the point H. The middle end of the wire ⅴ-13 is connected to the wire ⅵ-14 at the point D, and the other end of the wire ⅵ-14 is connected to the capacitor ⅰ-21. The capacitor ⅲ-11 is connected to the diode ⅰ-19 at the point H. -21 has a lower end connected to the wire ⅶ-15 to the capacitor ⅱ-22, the middle end of the wire ⅶ-15 is connected to the wire ⅷ-16 from point E to point B, the lower end of the capacitor ⅱ-22 is connected to the wire ⅸ-17 to the point F of the wire ⅹ-18, one end of the wire ⅹ-18 is connected to the diode ⅱ-20, and the other end is connected to point I, the other end of the diode ⅱ-20 is connected to the wire ⅳ-12 through point G to point C; the right end of the conversion circuit module II is provided with a connecting wire ⅹⅰ-23 and a wire ⅹⅱ-24 connected to the energy storage module III.

[0011] The output voltage of the high voltage power supply 25 is 2 kV.

[0012] The flow rate of the injection tube 31 is 0.12 ml / h.

[0013] The inner diameter of the needle 30 is 100 μm.

[0014] The heating temperature of the muffle furnace 37 is 875°C.

[0015] The capacitance of capacitor ⅰ-21 and capacitor ⅱ-22 are both 100nF.

[0016] The capacity of energy storage module III is 20mAh.

[0017] Beneficial effects of the utility model: the utility model utilizes the electrojet printing method to achieve an accuracy of less than 1 micron, thus avoiding the problem of low resolution caused by traditional casting method and silk screen printing method.

[0018] The utility model prepares the piezoelectric material into a film with a thickness of less than 10 μm, thereby avoiding the problem that the large flexible deformation and the high piezoelectric constant of the traditional material cannot be taken into account at the same time, effectively improving the charge output and the power generation.

[0019] The utility model adopts a co-firing connection method and utilizes electrospray printing technology to directly print PZT on a flexible conductive substrate, effectively avoiding the adhesive layer from absorbing deformation, promoting more direct charge transfer, and avoiding the problem of device failure caused by the increase in the adhesive layer.

[0020] The utility model utilizes the electric jet printing technology to manufacture a generator with a minimum size of 50 μm to 2 cm. The utility model can adapt to environmental changes and can be used normally in various complex environments. The manufacturing cost is low and the application is wide.

[0021] The utility model prepares the cantilever beam of the piezoelectric thick film generator into a trapezoidal structure that is narrow in the front and wide in the back, which effectively increases the flexible deformation and reduces the fracture problem caused by the vibration of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the micro flexible piezoelectric thick film generator of the utility model.

[0023] Figure 2 This is a schematic diagram of the power generation process of the micro flexible piezoelectric thick film generator device of the utility model.

[0024] Figure 3 This is a schematic diagram of the integrated co-firing of the micro flexible piezoelectric thick film generator of the utility model.

[0025] Figure 4 This is a polarization schematic diagram of the micro flexible piezoelectric thick film generator of the utility model.

[0026] Figure 5 This is a schematic diagram of the electrospray printing of the micro flexible piezoelectric generator of the utility model.

[0027] Figure 6 This is a schematic diagram of the voltage output curve of the micro flexible piezoelectric generator of the utility model.

[0028] In the figure: Ⅰ. Generator module, Ⅱ. Conversion circuit module, Ⅲ. Energy storage module, 1. Flexible conductive substrate, 2. PZT piezoelectric thick film, 3. Upper electrode, 4. Base, 5. Pillar, 6-1. Conductive silver paste ⅰ, 6-2. Conductive silver paste ⅱ, 7. Flexible connecting rod, 8. Wind blade, 9. Wire ⅰ, 10. Wire ⅱ, 11. Wire ⅲ, 12. Wire ⅳ, 13. Wire ⅴ, 14. Wire ⅵ, 15. Wire ⅶ, 16. Wire ⅷ, 17. Wire ⅸ, 18. Wire ⅹ, 19. Diode ⅰ, 20. Diode ⅱ, 21 .Capacitor ⅰ, 22. Capacitor ⅱ, 23. Wire ⅹⅰ, 24. Wire ⅹⅱ, 25. High-voltage power supply, 26. Wire ⅹⅲ, 27. Jet base, 28. Fine jet, 29. Taylor cone, 30. Spray needle, 31. Injection tube, 32. Miniature camera, 33. Host computer, 34. Micro-energy injector, 35. Wire ⅹⅳ, 36. Wire ⅹⅴ, 37. Muffle furnace, 38. Temperature setting key, 39. Display panel, 40. Polarization table, 41. Polarization table knob, 42. Wire ⅹⅵ, 43. Wire ⅹⅶ, 44. Polarization power supply. DETAILED DESCRIPTION

[0029] The utility model is further described in conjunction with the technical scheme and the accompanying drawings.

[0030] The micro-energy injector 34 is connected to the injection tube 31, which contains PZT material. The injection tube 31 is connected to the spray needle 30, and the high-voltage power supply 25 is connected to the spray needle 30 through the wire ⅹⅲ-26. The jet base 27 is grounded and movable. A stable voltage of 2kV is generated between the spray needle 30 and the jet base 27. The PZT material forms a stable Taylor cone 29 under the action of external voltage and gravity, and then forms a stable fine jet 28. One end of the host computer 33 is connected to the jet base 27, which can control the movement of the jet base 27, and the other end is connected to the micro camera 32 for observing the formed PZT piezoelectric thick film 2. The printed functional microstructure is placed in a structure with a bottom layer of a flexible conductive substrate 1, a middle layer of a PZT piezoelectric thick film 2, and an upper layer of an upper electrode 3 to form a piezoelectric thick film generator structure. The piezoelectric thick film generator structure is placed in a muffle furnace 37 for co-firing. After annealing, a polarization treatment is performed using a polarization power supply 44 to obtain a piezoelectric thick film generator. The base 4 is fixed on a support 5, and the piezoelectric thick film generator is installed on the support 5. The wind blade 8 is suspended on the bottom of the end of the cantilever beam extending from one side of the flexible conductive substrate 1 through a flexible connecting rod 7. The low-power alternating current is introduced into the conversion circuit module II through the wire i-9 and the wire ii-10. The conversion circuit module II converts the low-power alternating current into high-power direct current. The high-power direct current is introduced into the energy storage module III for storage using the wire xi-23 and the wire xii-24.

[0031] The specific implementation steps of the embodiment are as follows:

[0032] 1) Printing functional microstructures

[0033] A high voltage of 2kV is applied between the nozzle needle 30 and the jet base 27. Under the action of the gravity field and the electric field, the PZT material in the injection tube 31 flows out of the nozzle needle 30 to form a stable Taylor cone 29, and then forms a stable fine jet 28. The printing substrate is placed on the jet base 27. One end of the host computer 33 controls and drives the jet base 27 to move. The other end of the host computer 33 is connected to a micro camera 32 to observe and record the printing situation. The above content is Figure 3 It is reflected in.

[0034] 2) Integrated co-firing

[0035] like Figure 4 As shown, the printed PZT piezoelectric thick film 2 is stacked with the flexible conductive substrate 1 and the upper electrode 3, and co-fired in a muffle furnace 37. The co-firing temperature is adjusted to 875°C, and then annealed after its surface crystallization is observed to perform polarization treatment on the piezoelectric thick film generator.

[0036] 3) Functional microstructure polarization

[0037] like Figure 5As shown, the co-fired piezoelectric thick film generator is placed on a polarization table 40, and the upper electrode 3 is connected to the positive electrode of the polarization power supply 44 by using a wire ⅹⅵ-42, and the flexible conductive substrate 1 is connected to the negative electrode of the polarization power supply 44 by using a wire ⅹⅶ-43, and a polarization operation is performed. After the polarization, the grain electric domain arrangement of the piezoelectric thick film generator tends to be orderly, and it shows polarity to the outside.

[0038] 4) Power generation module and power generation device

[0039] like Figure 1 As shown, this piezoelectric thick film generator is composed of three layers of sheet structures, the lower layer is a rectangular flexible conductive substrate 1, one side of the flexible conductive substrate 1 extends outward to form a long cantilever beam structure, the middle layer is a PZT piezoelectric thick film 2, and the upper layer is an upper electrode 3. The upper, middle and lower three layers have the same shape and their areas decrease in proportion from bottom to top. Figure 2 It is shown in the figure that the lower layer is a rectangular flexible conductive substrate 1, a cantilever extends from one side of the flexible conductive substrate 1, a flexible connecting rod 7 is hung at the lower end of the cantilever, and a wind blade 8 is hung on the flexible connecting rod 7. The middle layer structure of the piezoelectric thick film generator is a PZT piezoelectric thick film 2 with the same shape as the flexible conductive substrate 1 and a smaller size than each side of the flexible conductive substrate 1. The flexible conductive substrate 1 and the PZT piezoelectric thick film 2 are connected in a glue-free manner. The glue-free connection makes the charge transfer controllable and the power generation large. The PZT piezoelectric thick film 2 is made into a thickness of 10μm, so that it has both high voltage electrical properties and high flexibility. The upper structure is an upper electrode 3, and conductive silver paste ⅰ-6-1 is dropped on the upper electrode 3. Conductive silver paste ⅱ-6-2 is dropped on the flexible conductive substrate 1. The conductive silver paste ⅰ-6-1 and the conductive silver paste ⅱ-6-2 play the role of conducting and fixing the wires. The conductive silver paste ⅰ-6-1 on the upper electrode 3 leads to a wire ⅰ-9 connected to the A end of the conversion circuit module, and the conductive silver paste ⅱ-6-2 on the flexible conductive substrate 1 leads to a wire ⅱ-10 connected to the B end of the conversion circuit module.

[0040] The unidirectional conduction of the diode and the charging and discharging characteristics of the capacitor are used to achieve charge accumulation and high voltage output. ac When the upper end is positive and the lower end is negative, the current flows from point A through wire ⅲ-11 and passes through point C. A part of the current flows through wire ⅳ-12 and passes through point G to diode ⅱ-20. Because the diode has unidirectional conductivity, the current cannot pass through diode ⅱ-20. Another part of the current flows into diode ⅰ-19. After the current comes out, it flows into wire ⅴ-13 and passes through point D to wire ⅵ-14. Therefore, capacitor ⅰ-21 gives V ac When charged, the PZT piezoelectric thick film 2 will bend upward.

[0041] When V acWhen the upper end is negative and the lower end is positive, the current flows from point B through wire ⅷ-16 and then through point E. A part of the current flows through wire ⅶ-15 into wire ⅵ-14 and then through point D to diode ⅰ-19. Because the diode has unidirectional conductivity, the current cannot pass through diode ⅰ-19. Another part of the current flows into diode ⅰ-19, and then flows into wire ⅸ-17 through point F to wire ⅹ-18 and then into diode ⅱ-20. Therefore, capacitor ⅱ-22 gives V ac When charged, the PZT piezoelectric thick film 2 will bend downward. Since the capacitor i-21 and the capacitor ii-22 are connected in series, the output voltage between point H and point I is the sum of the voltages across the two capacitors.

[0042] The high-power direct current converted by the micro-energy conversion circuit module II is transmitted to the energy storage module III through the conductor ⅹⅰ-23 and the conductor ⅹⅱ-24. The energy storage module III with a capacity of 20 mAh stores the high-power direct current.

[0043] 5) Voltage output process

[0044] Use a precision multimeter to directly measure the open circuit voltage generated by the PZT piezoelectric thick film 2 generator. Figure 6 As can be seen from the dotted curve in the figure, the open circuit output voltage V 0 It undergoes periodic changes as it deforms. The voltage fluctuates from -2V to 2V. The magnitude of the positive voltage is twice that of the negative voltage. However, this AC voltage cannot be directly used as a power source for electrical loads in practical applications.

[0045] from Figure 6 It can be seen from the solid curve in that after the conversion circuit, the output voltage undergoes a conversion from AC voltage to DC voltage. It should be noted that due to the initial instability of the piezoelectric excitation source, the output voltage will not quickly reach 2V in the first few cycles. 0 On the contrary, as the number of bending deformations accumulates, the output voltage gradually increases. After several cycles, the output voltage stabilizes at 4V, V 0 The voltage peak reaches 2V, achieving an output voltage twice the original voltage.

Claims

1. A structure of a micro flexible piezoelectric thick film generator, characterized in that: The piezoelectric thick film generator is composed of three stacked sheet structures, wherein the lower layer is a rectangular flexible conductive substrate (1), one side of the flexible conductive substrate (1) extends outward to form a long cantilever beam structure, the middle layer is a PZT piezoelectric thick film (2), and the upper layer is an upper electrode (3), wherein the upper, middle and lower three-layer structures have the same shape and their areas decrease in proportion from bottom to top.

2. A power generation device using the structure of a micro flexible piezoelectric thick film generator according to claim 1, characterized in that: A base (4) is provided on which a generator support (5) is fixed, and the piezoelectric thick film generator is fixed on the support (5); the flexible conductive substrate (1) and the upper electrode (3) are respectively dripped with conductive silver paste i (6-1) and conductive silver paste ii (6-2); a flexible connecting rod (7) is provided, the upper end of the flexible connecting rod (7) is connected to the conductive silver paste ii (6-2) below the tail end of the flexible conductive substrate (1) and the lower end is connected to the wind blade (8); one end of the wire i (9) is connected to the conductive silver paste i (6-1) on the upper electrode (3) and the other end is connected to the A end of the conversion circuit module II; one end of the wire ii (10) is connected to the conductive silver paste ii (6-2) below the tail end of the flexible conductive substrate (1) and the other end is connected to the B end of the conversion circuit module II; one end of the wire i (9) is connected to the conductive silver paste ii (6-2) below the tail end of the flexible conductive substrate (1) and the other end is connected to the B end of the conversion circuit module II. One end of the connecting wire iii (11) is connected to the diode i (19), the other end of the diode i (19) is connected to the wire v (13) to the point H, the middle end of the wire v (13) is connected to the wire vi (14) at the point D, the other end of the wire vi (14) is connected to the capacitor i (21), the lower end of the capacitor i (21) is connected to the wire vi (15) to the capacitor ii (22), the middle end of the wire vi (15) is connected to the wire ⅷ ( 16) to point B, the lower end of capacitor ii (22) is connected to wire ix (17) to point F of wire x (18), one end of wire x (18) is connected to diode ii (20), and the other end is connected to point I, the other end of diode ii (20) is connected to wire iv (12) through point G to point C; the right end of conversion circuit module II is provided with connecting wire xi (23) and wire xi (24) connected to energy storage module III.

3. The power generation device using a micro flexible piezoelectric thick film generator structure according to claim 2 is characterized in that: The capacitance of the capacitor i (21) and the capacitor ii (22) are both 100nF.

4. The power generation device using a micro flexible piezoelectric thick film generator structure according to claim 2 is characterized in that: The capacity of the energy storage module III is 20 mAh.

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