Method for manufacturing a piezoelectric thin film with functional microstructure based on pzt and pu

Abstract

This invention provides a method for preparing a piezoelectric thin film with functional microstructures based on PZT and PU, which saves significant costs, simplifies the process, and is easy to operate. The invention includes the following steps: Step 1: Particle modification; Step 2: Microstructure fabrication, including the following steps: adding PZT powder to a THF organic solvent, followed by ultrasonic dispersion to prevent particle agglomeration; adding PU after ultrasonication, stirring, evaporating, and allowing to stand; laying the above solution on a photolithographic silicon mold, drying it in an oven, and finally demolding with alcohol to obtain a piezoelectric thin film with a functional microstructure array.

Description

Technical Field

[0001] This invention relates to a method for preparing a functional microstructured piezoelectric thin film based on PZT and PU. Background Technology

[0002] Piezoelectric composites, as a novel type of composite material, combine piezoelectric particles as additives with polymer materials as the matrix. While single piezoelectric ceramics possess high electromechanical coupling coefficients and piezoelectric properties, they are relatively brittle. Pure polymer materials, on the other hand, are easy to process and have good flexibility, but their piezoelectric and dielectric properties are relatively low. By combining piezoelectric particles with polymer materials, the material can retain its excellent initial piezoelectric properties and electromechanical coupling coefficients while also possessing good mechanical properties, ease of processing, and low cost. It is currently being applied in fields such as medical and health monitoring, ultrasound, and energy recovery.

[0003] Traditional piezoelectric composite materials are typically film structures, resulting in low sensitivity and resolution when used as sensors or energy harvesters. In contrast, piezoelectric thin films with functional microstructures offer the advantage of higher sensitivity and resolution, enabling responses to minute signals (such as those generated by breathing or walking) and a higher signal-to-noise ratio. Currently, micron-scale processes with independent functional microstructures are relatively rare, and microstructures in composite materials are even scarcer. Furthermore, these structures are generally achieved through techniques such as photolithography and 3D printing, leading to high costs and complex manufacturing processes. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings in the prior art and to provide a method for preparing a functional microstructure piezoelectric thin film based on PZT and PU with a reasonable structural design, which saves a lot of costs, simplifies the process, and is easy to operate.

[0005] The technical solution adopted by this invention to solve the above problems is: a method for preparing a functional microstructured piezoelectric thin film based on PZT and PU, characterized by comprising the following steps:

[0006] Step 1: Particle modification, including the following steps:

[0007] (1) Weigh a certain amount of PZT powder and dry it at a drying temperature of 110-130℃; the PZT particle size in the powder is 3μm-500nm;

[0008] (2) Add the dried PZT powder to a mixed solution of silane coupling agent and acetone;

[0009] (3) Use ultrasonic dispersion to disperse the mixed solution to fully disperse and modify the particles; the ultrasonic dispersion time is 10-15 min and the ultrasonic dispersion power is 100W-120W;

[0010] (4) Stir the ultrasonically dispersed mixture on a magnetic stirrer at a temperature of 40-60℃, a speed of 750-850 r / min, and a stirring time of more than 1 hour;

[0011] (5) After stirring, let the reaction stand for 0.8-1.2h, then filter out the PZT particles, and then dry them at a temperature of 55-65℃ for 11-13h until they are dry.

[0012] (6) Wash the PZT particles with anhydrous ethanol and deionized water to remove excess unreacted coupling agent and acetone; dry them again at 110-130℃ and set aside for later use.

[0013] Step 2: Fabricate the microstructure, including the following steps:

[0014] (1) Weigh the modified PZT powder and add it to THF organic solvent to prepare a mixed solution; the mass fraction of PZT in the mixed solution is 60% to 80%;

[0015] (2) Disperse the mixed solution evenly by ultrasound. The ultrasound dispersion time is 10-15 min and the ultrasound dispersion power is 100W-120W to obtain PZT suspension.

[0016] (3) Weigh a certain mass of PU and add it to the PZT suspension. The mass ratio of PU to THF is 1:(9-11). Stir the mixture thoroughly on a magnetic stirrer at a speed of 800-1200 r / min for 48-72 h to obtain a mixed solution of PZT and PU. In the mixed solution of PZT and PU, the mass of PZT / mass of PZT+PU is 60-80%.

[0017] (4) After the obtained PZT and PU mixed solution is evaporated to the mass ratio of PU:THF = 1:8, it is allowed to stand for 48 to 72 hours to remove bubbles and produce a certain viscosity. Then, the bubbles in the solution are removed by vacuuming to obtain the mixed solution.

[0018] (5) Place the silicon wafer mold in a petri dish, clean and dry it with alcohol at a temperature of 35-45℃ for 15-20 minutes; spray a layer of Teflon on the silicon wafer mold.

[0019] (6) Slowly pour the PZT and PU mixed solution into the tilted culture dish until the solution completely covers the silicon wafer mold. Shake and shake the culture dish repeatedly to allow the solution to enter the silicon wafer mold. Place the culture dish at a certain tilt angle and let it stand for a certain period of time. The tilt angle is 10-20° and the standing time is 0.8-1.2h.

[0020] An ultrasonic transducer was used to assist the entry of a PZT and PU mixed solution into a silicon wafer mold.

[0021] (7) Place the silicon wafer mold and culture dish back into the vacuum chamber and evacuate; the filling process is completed within 10 minutes; after taking it out, place the silicon wafer mold horizontally for 11-13 hours;

[0022] (8) Dry at different temperatures for different times: first dry at 35-45℃ for 24-48 hours, then dry at 55-65℃ for 7-8 days;

[0023] (9) Pour alcohol into the dried petri dish to release the mold; this completes the preparation of the functional microstructure piezoelectric film based on PZT and PU composite materials;

[0024] (10) The piezoelectric thin film with functional microstructure is deposited on a gold electrode in a particle sputtering instrument and polarized in silicone oil at 70-90℃ for 1.8-2.2h at 17-22kv / mm using a high voltage power supply; the piezoelectric thin film with functional microstructure has piezoelectric properties after polarization.

[0025] In step one (1) of the present invention, the drying temperature is 120°C.

[0026] In step one (4) of the present invention, the stirring temperature is 50℃, the stirring speed is 800r / min, and the stirring time is 2h.

[0027] In step one (5) of this invention, the drying temperature is 60°C and the drying time is 12h.

[0028] In step two (3) of this invention, PU:THF = 1:10.

[0029] In step two (6) of this invention, shake 3 to 5 times, each time for 5 to 8 minutes.

[0030] In step two (8) of the present invention, the product is first dried at 40°C for 24-48 hours, and then dried at 60°C for 7-8 days.

[0031] The microstructured monomer pillars on the functional microstructured piezoelectric thin film described in this invention are square pillars.

[0032] The microstructure monolithic column of the present invention has a length, width and height of 80×80×140μm, 30×30×140μm or 3×3×10μm.

[0033] The silicon wafer mold described in this invention is processed using photolithography.

[0034] Compared with the prior art, the present invention has the following advantages and effects:

[0035] 1. This invention uses PZT piezoelectric particles as additives and PU polymer material as the matrix to fabricate functional microstructure piezoelectric films. The PZT particles are uniformly distributed, have good interfacial bonding, and possess excellent mechanical properties, thus giving the functional microstructure piezoelectric films excellent piezoelectric properties. Most importantly, existing microstructure fabrication methods rely on pure polymer materials, requiring costly and complex processes such as photolithography or 3D printing. This invention, however, utilizes composite materials to fabricate micron-scale functional structures, which is extremely rare, and the use of piezoelectric particles and polymer materials to fabricate functional microstructures is unprecedented. Furthermore, it significantly reduces costs, simplifies the process, and is easy to operate.

[0036] 2. This invention uses photolithography silicon wafer molds to fabricate piezoelectric thin films with functional microstructures, which can respond to low-frequency and minute vibrations, thus having high sensitivity and resolution. It can be applied to medical wearable devices, health monitoring sensors, and energy recovery devices powered by non-microelectronic devices.

[0037] 3. Through this invention, the minimum length, width and height of the microstructure monolith can be made into a composite material columnar structure of 3×3×10μm, which is much smaller than the existing technology. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the piezoelectric thin film prepared according to an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the microstructured monolith prepared according to an embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of the back structure when using interdigitated electrodes for electrode plating according to an embodiment of the present invention.

[0041] Figure 4 This is a front structural diagram of an embodiment of the present invention when using interdigitated electrodes for electrode plating.

[0042] Figure 5 This is a front view of the structure when electrodes are plated on the upper and lower surfaces according to an embodiment of the present invention.

[0043] Figure 6 This is a schematic diagram of the back structure when electrodes are plated on the upper and lower surfaces in an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0045] The embodiments of the present invention include the following steps:

[0046] Step 1: Particle modification, including the following steps:

[0047] (1) Weigh a certain amount of PZT powder and dry it at a drying temperature of 110-130℃. The PZT particle size in the powder is 3μm-500nm. In this embodiment, the drying temperature is 120℃. PZT is lead zirconate titanate piezoelectric ceramic.

[0048] (2) Add the dried PZT powder to a mixed solution of silane coupling agent and acetone (model KBM-503);

[0049] (3) Use ultrasonic dispersion to disperse the mixed solution to fully disperse and modify the particles; the ultrasonic dispersion time is 10-15 min and the ultrasonic dispersion power is 100W-120W;

[0050] (4) The ultrasonically dispersed mixture is stirred on a magnetic stirrer at a temperature of 40-60℃, a speed of 750-850 r / min, and a stirring time of more than 1 hour. In this embodiment, the stirring temperature is 50℃, the stirring speed is 800 r / min, and the stirring time is 2 hours.

[0051] (5) After stirring, let the reaction stand for 0.8-1.2 hours. In this example, the reaction stands for 1 hour. Then filter out the PZT particles and dry them. The drying temperature is 55-65℃ and the drying time is 11-13 hours until they are dry. In this example, the drying temperature is 60℃ and the drying time is 12 hours.

[0052] (6) Wash the PZT particles twice with anhydrous ethanol and deionized water to completely remove excess unreacted coupling agent and acetone; dry them again at 110-130℃ and wait for use.

[0053] Step 2: Fabricate the microstructure, including the following steps:

[0054] (1) Weigh the modified PZT powder and add it to THF (tetrahydrofuran) organic solvent to prepare a mixed solution;

[0055] (2) Disperse the mixed solution evenly with ultrasound. The ultrasound dispersion time is 10-15 min and the ultrasound dispersion power is 100W-120W to obtain PZT suspension.

[0056] (3) Weigh a certain amount of PU (polyurethane) and add it to the PZT suspension. The mass ratio of PU to THF is 1: (9-11). In this embodiment, PU to THF is 1:10.

[0057] The mass ratio of PU to THF is 1:8, which is actually the optimal microstructure molding ratio, and also the final required ratio. However, during the preparation stage, in order to accelerate the dissolution of PU or to reduce solvent loss during ultrasonic dispersion, more solvent is added, up to a ratio of 1:9 to 1:11. After a certain period of time, the excess solvent (THF has a boiling point of 66℃ and is highly volatile) is evaporated until the optimal ratio of 1:8 is achieved before proceeding to step (4).

[0058] The mixture was thoroughly stirred on a magnetic stirrer at a speed of 800-1200 r / min for 48-72 h to obtain a PZT and PU mixed solution. In the PZT and PU mixed solution, the mass ratio of PZT to PZT+PU was 60-80%, and the mass ratio of PU to THF was 1:8.

[0059] The 60-80% concentration is chosen because below 60%, the piezoelectric properties are poor and the output electrical signal is small (generally negligible, but noticeable above 60%). Adding above 80% is problematic because PZT is a ceramic powder; increasing the mass fraction drastically increases the elastic modulus of the piezoelectric film, leading to increased stiffness and hardness. This can cause the film to crack or even break with slight bending. Theoretically, too many particles and insufficient solute between them result in a porous material, leading to poor bonding between particles and the matrix, directly impacting material properties.

[0060] A PU:THF mass ratio of 1:8 provides the optimal viscosity for microstructure molding. A ratio lower than this results in a solution that is too viscous to enter the mold, preventing microstructure formation. Conversely, a ratio higher than this results in a solution that is too dilute, causing PZT particles to sink and leading to uneven distribution of piezoelectric particles within the piezoelectric film. The 1:8 ratio provides the perfect viscosity to support the particles, preventing sinking, while also ensuring smooth flow of the solution into the mold.

[0061] (4) After evaporating the obtained PZT and PU mixed solution to a PU:THF mass ratio of 1:8, let it stand for 48-72 hours to remove bubbles, and then remove the bubbles in the solution by vacuuming for 10 minutes to obtain a mixed solution with suitable viscosity. At 25℃, a 1:8 ratio generally corresponds to a kinematic viscosity of 47-50 mm² / s.

[0062] (5) Place the photolithographically etched silicon wafer mold in a petri dish, and clean and dry it with alcohol. The drying temperature is 35-45℃ and the drying time is 15-20 min. In this embodiment, the drying temperature is 40℃. Spray a layer of Teflon on the silicon wafer mold to facilitate the demolding of the microstructure film.

[0063] (6) Slowly pour the PZT and PU mixed solution into the tilted culture dish until the solution completely covers the silicon wafer mold. Shake the culture dish repeatedly for a certain period of time, 3 to 5 times, 5 to 8 minutes each time, so that the solution enters the silicon wafer mold. Place the culture dish at a certain angle and let it stand for a certain period of time. The tilt angle is 10 to 20° and the standing time is 0.8 to 1.2 hours. In this embodiment, the standing time is 1 hour.

[0064] (6) With the assistance of an ultrasonic transducer, apply a pressure of 1000J, 70-130kPa for 10min to help the PZT and PU mixed solution enter the silicon wafer mold.

[0065] (7) Place the silicon wafer mold and culture dish back into the vacuum chamber and evacuate the vacuum chamber. The silicon wafer mold has different sizes of pits: 80×80×140μm, 30×30×140μm, and 3×3×10μm. This diameter can be called a capillary. There will be a capillary effect, which will allow the solution to flow actively into the mold. Therefore, the solution can be penetrated into the silicon wafer mold cavity through the capillary filling process assisted by vacuum. Secondly, the air in the pits of the mold is extracted by vacuuming, and the solution will slowly flow into the mold. Otherwise, the solution and the air inside will form a pressure difference balance, which will prevent the solution from entering. On the other hand, the air bubbles in the solution are extracted. The combined effect of air pressure and capillary force assists the filling process to be completed within 10 minutes. After taking it out, place the silicon wafer mold horizontally for 11-13 hours. In this embodiment, the placement time is 12 hours.

[0066] (8) Drying at different temperatures for different times: first, dry at 35-45℃ for 24-48 hours to allow for slow molding, and then dry at 55-65℃ for 7-8 days to fully remove the unvolatile solvent; in this embodiment, first dry at 40℃ for 24-48 hours, and then dry at 60℃ for 7-8 days.

[0067] (9) After drying, alcohol was poured into the petri dish to release the mold, resulting in a piezoelectric film with functional microstructures. This completes the preparation of the piezoelectric film with functional microstructures based on PZT and PU composite materials. The microstructure monomer pillars on the piezoelectric film with functional microstructures are square prisms, with three dimensions: 80×80×140μm, 30×30×140μm, and 3×3×10μm.

[0068] (10) The functional microstructure piezoelectric thin film is deposited with gold electrodes in an ion sputtering apparatus using two methods: interdigitated electrodes and electrodes deposited on both the upper and lower surfaces. The film is then polarized at 17-22 kV / mm in silicone oil at 70-90°C for 1.8-2.2 hours. After polarization, the functional microstructure piezoelectric thin film acquires piezoelectric properties. Generally, an electric field greater than 22 kV / mm will cause electrical breakdown, leading to sample damage. The performance increases from 17-22 kV / mm, and is generally best approached to 22. In this embodiment, the film is polarized at 22 kV / mm in silicone oil at 80°C for 2 hours.

[0069] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components, etc. The above description is merely illustrative of the structure of the present invention. All equivalent or simple variations made based on the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, all of which should fall within the protection scope of this invention.

Claims

1. A method for preparing a functional microstructured piezoelectric thin film based on PZT and PU, characterized in that: Includes the following steps: Step 1: Particle modification, including the following steps: (1) Weigh a certain amount of PZT powder and dry it at a drying temperature of 110-130℃; the PZT particle size in the powder is 3μm-500nm; (2) Add the dried PZT powder to a mixed solution of silane coupling agent and acetone; (3) Use ultrasonic dispersion to disperse the mixed solution to fully disperse and modify the particles; the ultrasonic dispersion time is 10-15 min and the ultrasonic dispersion power is 100W-120W; (4) Stir the ultrasonically dispersed mixture on a magnetic stirrer at a temperature of 40-60℃, a speed of 750-850 r / min, and a stirring time of more than 1 hour; (5) After stirring, let the reaction stand for 0.8-1.2h, then filter out the PZT particles, and then dry them at a temperature of 55-65℃ for 11-13h until they are dry. (6) Wash the PZT particles with anhydrous ethanol and deionized water respectively to remove excess unreacted coupling agent and acetone; dry them again at 110-130℃ and wait for use. Step 2: Fabricate the microstructure, including the following steps: (1) Weigh the modified PZT powder and add it to THF organic solvent to prepare a mixed solution; the mass fraction of PZT in the mixed solution is 60% to 80%; (2) Disperse the mixed solution evenly by ultrasound. The ultrasound dispersion time is 10-15 min and the ultrasound dispersion power is 100W-120W to obtain PZT suspension. (3) Weigh a certain mass of PU and add it to the PZT suspension. The mass ratio of PU to THF is 1:(9-11). Stir the mixture thoroughly on a magnetic stirrer at a speed of 800-1200 r / min for 48-72 h to obtain a mixed solution of PZT and PU. In the mixed solution of PZT and PU, the mass of PZT / mass of PZT+PU is 60-80%. (4) After the obtained PZT and PU mixed solution is evaporated to the mass ratio of PU:THF = 1:8, it is allowed to stand for 48 to 72 hours to remove bubbles and produce a certain viscosity. Then, the bubbles in the solution are removed by vacuuming to obtain the mixed solution. (5) Place the silicon wafer mold in a petri dish, clean and dry it with alcohol at a temperature of 35-45℃ for 15-20 minutes; spray a layer of Teflon on the silicon wafer mold. (6) Slowly pour the PZT and PU mixed solution into the tilted culture dish until the solution completely covers the silicon wafer mold. Shake and shake the culture dish repeatedly to allow the solution to enter the silicon wafer mold. Place the culture dish at a certain tilt angle and let it stand for a certain period of time. The tilt angle is 10-20° and the standing time is 0.8-1.2h. An ultrasonic transducer was used to assist the entry of a PZT and PU mixed solution into a silicon wafer mold. (7) Place the silicon wafer mold and culture dish back into the vacuum chamber and evacuate; the filling process is completed within 10 minutes; after taking it out, place the silicon wafer mold horizontally for 11-13 hours; (8) Dry at different temperatures for different times: first dry at 35-45℃ for 24-48 hours, then dry at 55-65℃ for 7-8 days; (9) Pour alcohol into the dried petri dish to release the mold; this completes the preparation of the functional microstructure piezoelectric film based on PZT and PU composite materials; (10) The piezoelectric thin film with functional microstructure is deposited on a gold electrode in a particle sputtering instrument and polarized in silicone oil at 70-90℃ for 1.8-2.2h at 17-22kv / mm using a high voltage power supply; the piezoelectric thin film with functional microstructure has piezoelectric properties after polarization.

2. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step one (1), the drying temperature is 120℃.

3. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step one (4), the stirring temperature is 50℃, the stirring speed is 800r / min, and the stirring time is 2h.

4. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step one (5), the drying temperature is 60℃ and the drying time is 12h.

5. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step two (3), PU:THF = 1:

10.

6. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step two (6), shake 3 to 5 times, each time for 5 to 8 minutes.

7. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: In step two (8), the product is first dried at 40°C for 24-48 hours, and then dried at 60°C for 7-8 days.

8. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: The microstructure monomer pillars on the piezoelectric thin film with functional microstructures are square pillars.

9. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 8, characterized in that: The microstructure monoliths have length, width, and height of 80×80×140μm, 30×30×140μm, or 3×3×10μm.

10. The method for preparing a functional microstructured piezoelectric thin film based on PZT and PU according to claim 1, characterized in that: The silicon wafer mold is processed using photolithography.

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