Piezoelectric ceramic film and method for manufacturing the same

Abstract

This invention discloses a piezoelectric ceramic membrane and its preparation method, comprising a modified lead zirconate titanate-based ceramic and a surface functional coating. The modified lead zirconate titanate-based ceramic serves as the substrate, wherein x = 0.52-0.54, and contains A-site doping elements, B-site doping elements, and sintering aids. The surface functional coating is silicon nitride, with a thickness of 100-300 nm, and is prepared by low-pressure chemical vapor deposition (LPCVD). This invention, through La, Nb, Sr, and Mn multi-component composite doping, significantly reduces the temperature coefficients of the piezoelectric constant d31 and the electromechanical coupling coefficient k31, achieving a displacement drift ≤ ±3% over a wide temperature range of -20℃ to 85℃, ensuring stable micro-infusion accuracy under different environments. The integrated composite membrane structure with a central island and annular support improves displacement linearity while ensuring a large stroke, reducing hysteresis and creep, and meeting the ultra-high precision infusion requirements of 0.05U~0.01U.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic film technology, specifically a piezoelectric ceramic film and its preparation method. Background Technology

[0002] In the field of microfluidic delivery, especially in patch insulin pumps, microfluidic chips, and precision drug delivery systems, piezoelectric ceramic micropumps are gradually replacing traditional mechanical pumps, peristaltic pumps, and electromagnetic pumps due to their advantages such as fast response, small size, low power consumption, and no electromagnetic interference.

[0003] Currently, most commercially available piezoelectric ceramic membranes use the conventional lead zirconate titanate (PZT) system, which has significant drawbacks: 1) Poor temperature stability: the piezoelectric constant and electromechanical coupling coefficient change significantly with ambient temperature, leading to pumping accuracy drift and failing to meet the requirements for 0.05U or even 0.01U level micro-infusion of insulin; 2) Traditional piezoelectric membranes cannot directly contact the drug solution, requiring the addition of a hydraulic coupling layer, increasing dead volume, reducing driving efficiency, and introducing temperature drift and leakage risks; 3) Simple membrane structure design, poor stroke linearity, and significant hysteresis and creep, affecting the accuracy of repeated infusions; 4) Insufficient biocompatibility: direct contact with insulin easily causes drug adsorption and denaturation, making it difficult to meet the safety standards for medical implants and wearable devices. Therefore, we propose a piezoelectric ceramic membrane and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a piezoelectric ceramic film and its preparation method to solve the problems in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a piezoelectric ceramic film, which is composed of modified lead zirconate titanate-based ceramic and a surface functional coating; The modified lead zirconate titanate-based ceramic is The matrix is ​​composed of x = 0.52-0.54 and contains A-site dopant, B-site dopant and sintering aid; The surface functional coating is silicon nitride. The thickness of the surface functional coating is 100-300 nm, and the surface functional coating is prepared by low-pressure chemical vapor deposition (LPCVD).

[0006] Preferably, the modified lead zirconate titanate-based ceramic comprises: : 92.0%-96.0%; 0.3%-1.0%; 0.2%-0.8%; 0.5%-1.5%; 0.1%-0.5%; 0.2%-0.6%; : 0.1%-0.4%.

[0007] Preferably, it includes a central island and a ring-shaped support structure, wherein the thickness of the central island is 10-30 μm and the thickness of the ring-shaped support structure is 5-15 μm; the central island and the ring-shaped support structure are an integrated ceramic structure.

[0008] Preferably, the silicon nitride coating is a low-stress dense coating, and the deposition temperature of the silicon nitride coating is 780-820℃.

[0009] Preferably, the piezoelectric constant d31 of the piezoelectric ceramic film is ≥-180pm / V, and the electromechanical coupling coefficient k31 of the piezoelectric ceramic film is ≥0.35; the displacement drift is ≤±3% in the range of -20℃ to 85℃.

[0010] A method for preparing a piezoelectric ceramic film includes the following steps: S1. Weigh according to the proportions. , , , , , , A uniform slurry was obtained by wet ball milling for 8-12 hours. S2. Dry the slurry, sieve it, and pre-calcine it at 850-950℃ for 2-4 hours to obtain pre-calcined powder; S3. The pre-fired powder is cast into a green film. S4. Sinter the green film at 1150-1250℃ for 2-3 hours until the density is ≥97% to obtain a ceramic substrate film; S5. Polish the ceramic substrate film on both sides, print the electrode and polarize it for 30-60 min at 120-150℃ and 3-5kV / mm electric field. S6. Deposit on the polarized ceramic substrate surface using LPCVD process. A coating is applied to obtain a piezoelectric ceramic film.

[0011] Preferably, in step S3, the thickness of the green film formed by casting is 20-50 μm.

[0012] Preferably, in step S4, the sintering atmosphere is air, and the heating rate is 3-5℃ / min.

[0013] Preferably, the process also includes a structural etching step: using DRIE (Deep Reactive Ion Etching) to process the ceramic substrate film to form a central island and a ring-shaped support structure.

[0014] Compared with the prior art, the beneficial effects of the present invention are: By using La, Nb, Sr, and Mn multi-component composite doping, the temperature coefficients of the piezoelectric constant d31 and the electromechanical coupling coefficient k31 are significantly reduced, and the displacement drift is ≤±3% in a wide temperature range of -20℃ to 85℃, ensuring stable accuracy of micro-infusion under different environments.

[0015] A 100-300nm LPCVD silicon nitride coating is deposited on the surface, which is chemically inert, biocompatibility meets the ISO10993 standard, has extremely low insulin adsorption, can be directly pumped, improves driving efficiency to over 85%, and significantly reduces dead volume.

[0016] The integrated composite membrane structure with a central island and ring support ensures a large stroke while improving displacement linearity, reducing hysteresis and creep, and meeting the ultra-high precision infusion requirements of 0.05U~0.01U.

[0017] It adopts a standardized MEMS-compatible process of tape casting, high-temperature sintering, polarization, DRIE etching and LPCVD deposition, which is suitable for wafer-level mass production and produces products with uniform and reliable performance. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] In the diagram: 1. Central island; 2. Circular support structure. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0021] Please see Figure 1 In this embodiment of the invention, a piezoelectric ceramic film is composed of modified lead zirconate titanate-based ceramic and a surface functional coating. The modified lead zirconate titanate-based ceramic is The matrix is ​​composed of x = 0.52-0.54 and contains A-site dopant, B-site dopant and sintering aid; The surface functional coating is silicon nitride. The thickness of the surface functional coating is 100-300 nm, and the surface functional coating is prepared by low-pressure chemical vapor deposition (LPCVD).

[0022] Preferably, the modified lead zirconate titanate-based ceramic comprises: : 92.0%-96.0%; 0.3%-1.0%; 0.2%-0.8%; 0.5%-1.5%; 0.1%-0.5%; 0.2%-0.6%; : 0.1%-0.4%.

[0023] Preferably, the device includes a central island 1 and an annular support structure 2, wherein the thickness of the central island 1 is 10-30 μm and the thickness of the annular support structure 2 is 5-15 μm; the central island 1 and the annular support structure 2 are an integrated ceramic structure. By modifying the PZT matrix with multi-element doping, the crystal phase composition and domain structure are optimized, improving piezoelectric performance and reducing temperature drift. The central island and annular support composite structure enables the membrane to generate uniform, linear, and repeatable micro-displacements under electric field drive, precisely controlling the pump cavity volume change. The surface LPCVD silicon nitride coating provides excellent biocompatibility and chemical stability, allowing the piezoelectric ceramic membrane to directly contact insulin and other drug solutions, eliminating the need for a hydraulic coupling layer and achieving high-efficiency, low dead volume, and high-precision direct pumping. Under the action of an applied driving voltage, the piezoelectric ceramic membrane undergoes inverse piezoelectric effect to produce controllable deformation, driving the membrane to reciprocate and complete the intake and exhaust of micro-fluids, meeting the ultra-precise, low-noise, long-endurance, and highly reliable infusion requirements of the medical field.

[0024] Preferably, the silicon nitride coating is a low-stress, dense coating, and the deposition temperature of the silicon nitride coating is 780-820℃. A 100-300nm LPCVD silicon nitride coating is deposited on the surface, exhibiting extremely strong chemical inertness, biocompatibility meeting ISO10993 standards, and very low insulin adsorption, enabling direct pumping, increasing driving efficiency to over 85%, and significantly reducing dead volume. Preferably, the piezoelectric constant d31 of the piezoelectric ceramic film is ≥-180pm / V, and the electromechanical coupling coefficient k31 of the piezoelectric ceramic film is ≥0.35; the displacement drift is ≤±3% in the range of -20℃ to 85℃.

[0025] A method for preparing a piezoelectric ceramic film includes the following steps: S1. Weigh according to the proportions. , , , , , , A uniform slurry was obtained by wet ball milling for 8-12 hours. S2. Dry the slurry, sieve it, and pre-calcine it at 850-950℃ for 2-4 hours to obtain pre-calcined powder; S3. The pre-calcined powder is cast into a green film; the thickness of the cast green film is 20-50 μm. S4. Sinter the green film at 1150-1250℃ for 2-3 hours until the density is ≥97% to obtain a ceramic substrate film; the sintering atmosphere is air and the heating rate is 3-5℃ / min. S5. Polish the ceramic substrate film on both sides, print the electrode and polarize it for 30-60 min at 120-150℃ and 3-5kV / mm electric field. S6. Deposit on the polarized ceramic substrate surface using LPCVD process. A coating is applied to obtain a piezoelectric ceramic film.

[0026] Preferably, the process also includes a structural etching step: processing the ceramic substrate film using DRIE deep reactive ion etching to form the central island 1 and the annular support structure 2.

[0027] The working principle of this invention is as follows: By modifying the PZT matrix with multiple dopants, the crystal phase composition and domain structure are optimized, improving piezoelectric performance and reducing temperature drift. A central island and ring-supported composite structure is adopted, enabling the membrane to generate uniform, linear, and repeatable micro-displacements under an electric field, precisely controlling the pump cavity volume change. The surface LPCVD silicon nitride coating provides excellent biocompatibility and chemical stability, allowing the piezoelectric ceramic membrane to directly contact insulin and other medications, eliminating the need for a hydraulic coupling layer and achieving high-efficiency, low dead volume, and high-precision direct pumping. Under the action of an applied driving voltage, the piezoelectric ceramic membrane undergoes the inverse piezoelectric effect, producing controllable deformation, driving the membrane to reciprocate, completing the intake and exhaust of micro-fluids, meeting the ultra-precise, low-noise, long-endurance, and highly reliable infusion requirements of the medical field.

[0028] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A piezoelectric ceramic membrane, characterized in that, It is composed of modified lead zirconate titanate-based ceramic and surface functional coating; The modified lead zirconate titanate-based ceramic is The matrix is ​​composed of x = 0.52-0.54 and contains A-site dopant, B-site dopant and sintering aid; The surface functional coating is silicon nitride. The thickness of the surface functional coating is 100-300 nm, and the surface functional coating is prepared by low-pressure chemical vapor deposition (LPCVD).

2. The piezoelectric ceramic membrane according to claim 1, characterized in that, The modified lead zirconate titanate-based ceramic comprises: : 92.0%-96.0%; 0.3%-1.0%; 0.2%-0.8%; 0.5%-1.5%; 0.1%-0.5%; 0.2%-0.6%; : 0.1%-0.4%.

3. The piezoelectric ceramic membrane according to claim 1, characterized in that, It includes a central island (1) and an annular support structure (2), wherein the thickness of the central island (1) is 10-30 μm and the thickness of the annular support structure (2) is 5-15 μm; the central island (1) and the annular support structure (2) are an integrated ceramic structure.

4. The piezoelectric ceramic membrane according to claim 1, characterized in that, The silicon nitride coating is a low-stress dense coating, and the deposition temperature of the silicon nitride coating is 780-820℃.

5. The piezoelectric ceramic membrane according to claim 1, characterized in that, The piezoelectric ceramic film has a piezoelectric constant d31 ≥ -180pm / V and an electromechanical coupling coefficient k31 ≥ 0.35; the displacement drift is ≤ ±3% in the range of -20℃ to 85℃.

6. A method for preparing a piezoelectric ceramic film according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh according to the proportions. , , , , , , A uniform slurry was obtained by wet ball milling for 8-12 hours. S2. Dry the slurry, sieve it, and pre-calcine it at 850-950℃ for 2-4 hours to obtain pre-calcined powder; S3. The pre-fired powder is cast into a green film. S4. Sinter the green film at 1150-1250℃ for 2-3 hours until the density is ≥97% to obtain a ceramic substrate film; S5. Polish the ceramic substrate film on both sides, print the electrode and polarize it for 30-60 min at 120-150℃ and 3-5kV / mm electric field. S6. Deposit on the polarized ceramic substrate surface using LPCVD process. A coating is applied to obtain a piezoelectric ceramic film.

7. The method for preparing a piezoelectric ceramic film according to claim 6, characterized in that, In step S3, the thickness of the green film formed by casting is 20-50 μm.

8. The method for preparing a piezoelectric ceramic film according to claim 6, characterized in that, In step S4, the sintering atmosphere is air, and the heating rate is 3-5℃ / min.

9. The method for preparing a piezoelectric ceramic film according to claim 6, characterized in that, It also includes a structural etching step: the ceramic substrate film is processed by DRIE deep reactive ion etching to form a central island (1) and a ring support structure (2).

Images