Piezoelectric ceramic micro-pump with composite driving structure

Abstract

The utility model discloses a piezoelectric ceramic micro -flow pump of composite drive structure, including T type fixed frame, composite ceramic actuating structure, pump cavity, water inlet check valve and water outlet check valve, T type fixed frame includes horizontal section and longitudinal section, horizontal section and longitudinal section inside intercommunication, pump cavity sets up in horizontal section, composite ceramic actuating structure sets up at both sides of longitudinal section, makes pump cavity, fixed frame and both sides composite ceramic actuating structure form a closed space together, water inlet check valve and water outlet check valve and pump cavity intercommunication, set up respectively at both sides of the bottom of pump cavity, through using composite ceramic actuating structure, make its driving force improve, can through the control composite ceramic actuating structure's actuating frequency to accurate control two check valve's liquid flow in use, has solved the existing piezoelectric drive and adopts cantilever beam structure, and there is the problem of insufficient driving force, big flow fluctuation.

Description

Technical Field

[0001] This utility model relates to the field of microfluidic pump technology, and in particular to a piezoelectric ceramic microfluidic pump with a composite drive structure. Background Technology

[0002] Commercially available electronic syringe pumps employ a mechanical structure, using a piston-driven mechanism to deliver liquids. Different operating states of the pump are determined by detecting the resistance of the plunger. However, due to piston resistance, this method is not very sensitive and applies significant cumulative pressure to the fluid path. This can lead to the infusion of large volumes of fluid in a short period during the instant a blockage is cleared, posing a certain safety hazard.

[0003] Therefore, to address the safety hazards of mechanical structures, piezoelectric ceramic micropumps with composite drive structures have become an important component of microfluidic technology. Their advantages, such as simple structure, thin and light size, low-frequency operation, and low power consumption, make them promising for applications in medicine, biology, chemistry, agriculture, beauty, and sanitary ware. As a core component of microfluidic systems, the design of micropumps is crucial.

[0004] However, most current piezoelectric drive solutions use cantilever beam structures, which suffer from insufficient driving force and large flow fluctuations. Summary of the Invention

[0005] Existing microfluidic pumps suffer from insufficient driving force and large flow fluctuations.

[0006] To address the aforementioned issues, a piezoelectric ceramic microfluidic pump with a composite drive structure is proposed. By using a composite ceramic actuation structure, the driving force is improved. The mechanical deformation is converted into a change in pump cavity volume by utilizing the pre-bent diaphragm component in the composite ceramic actuation structure. During use, the liquid flow rate of the two one-way valves can be precisely controlled by controlling the actuation frequency of the composite ceramic actuation structure. This solves the problems of insufficient driving force and large flow fluctuations in existing piezoelectric drives that mostly use cantilever beam structures.

[0007] A piezoelectric ceramic microfluidic pump with a composite drive structure includes:

[0008] T-shaped mounting bracket;

[0009] Composite ceramic actuation structure;

[0010] Pump chamber;

[0011] Inlet check valve and outlet check valve;

[0012] The T-shaped fixing frame includes a horizontal part and a vertical part;

[0013] The transverse portion is internally connected to the longitudinal portion;

[0014] The pump chamber is disposed within the transverse portion;

[0015] The composite ceramic actuation structure is disposed on both sides of the longitudinal section, so that the pump chamber, the fixing frame and the composite ceramic actuation structure on both sides together form a closed space;

[0016] The inlet check valve and the outlet check valve are connected to the pump chamber and are respectively located on both sides of the bottom of the pump chamber.

[0017] In a first possible embodiment of the piezoelectric ceramic microfluidic pump with the composite drive structure described in this utility model, the pump chamber includes:

[0018] Pump chamber membrane;

[0019] The pump chamber diaphragm is disposed on the side of the pump chamber facing the enclosed space.

[0020] In conjunction with the first possible embodiment of this utility model, and in the second possible embodiment, the composite ceramic actuation structure includes:

[0021] Piezoelectric ceramic stacked structure;

[0022] Pre-bent film assembly;

[0023] The pre-bent film assembly is mounted on the T-shaped fixing frame to form the sealed space;

[0024] The piezoelectric ceramic stack structure is disposed on the outside of the pre-bent film assembly, and the center point of the pre-bent film assembly is bonded to the center point of the piezoelectric ceramic stack structure.

[0025] In conjunction with the second possible embodiment of this utility model, and in the third possible embodiment, the piezoelectric ceramic stack structure includes:

[0026] Multi-layered curved ceramic sheet;

[0027] Insulating layer;

[0028] The insulating layer is disposed between the arc-shaped ceramic sheets for insulation.

[0029] In conjunction with the second possible embodiment of this utility model, and in the fourth possible embodiment, the pre-bent film assembly includes:

[0030] Pre-bent metal sheet;

[0031] Sealed film;

[0032] The sealing film is disposed on the inside of the pre-bent metal.

[0033] In conjunction with the third and fifth possible embodiments of this utility model, the number of arc-shaped ceramic sheets is three, and the insulating layer is made of epoxy resin material.

[0034] In conjunction with the fourth possible implementation of this utility model, and in the sixth possible implementation, the sealing film is made of polyimide material.

[0035] In conjunction with the fifth and seventh possible embodiments of this utility model, the thickness of the arc-shaped ceramic sheet is within 0.1-0.5 mm.

[0036] In conjunction with the sixth and eighth possible embodiments of this utility model, the thickness of the pre-bent metal sheet is within 70-100 μm, and the thickness of the sealing film is within 10-30 μm.

[0037] In conjunction with the sixth and ninth possible embodiments of this utility model, the radius of curvature of the pre-bent film assembly is within 10-20 mm.

[0038] The piezoelectric ceramic microfluidic pump with a composite drive structure described in this utility model improves its driving force by using a composite ceramic actuation structure. By utilizing the pre-bent diaphragm component in the composite ceramic actuation structure, mechanical deformation is converted into changes in pump cavity volume. In use, the liquid flow rate of the two one-way valves can be precisely controlled by controlling the actuation frequency of the composite ceramic actuation structure. This solves the problems of insufficient driving force and large flow fluctuations in existing piezoelectric drives that mostly use cantilever beam structures. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a structural diagram of the piezoelectric ceramic microfluidic pump with a composite drive structure in this utility model;

[0041] Figure 2 This is a cross-sectional view of the piezoelectric ceramic microfluidic pump with a composite drive structure in this utility model;

[0042] Figure 3 This is a diagram of the piezoelectric ceramic stacked structure in the piezoelectric ceramic microfluidic pump with composite drive structure in this utility model;

[0043] The parts referred to by the numbers in the attached figure are as follows: 110 - transverse part, 120 - longitudinal part, 200 - composite ceramic actuation structure, 210 - pre-bent diaphragm assembly, 220 - piezoelectric ceramic stacked structure, 300 - inlet check valve, 400 - outlet check valve, 500 - pump chamber, 510 - pump chamber diaphragm. Detailed Implementation

[0044] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of this utility model.

[0045] Existing microfluidic pumps suffer from insufficient driving force and large flow fluctuations.

[0046] To address the above problems, a piezoelectric ceramic microfluidic pump with a composite drive structure is proposed.

[0047] A piezoelectric ceramic microfluidic pump with a composite drive structure includes a T-shaped mounting bracket, a composite ceramic actuation structure 200, a pump chamber 500, an inlet check valve 300, and an outlet check valve 400. The T-shaped mounting bracket includes a transverse portion 110 and a longitudinal portion 120; the transverse portion 110 and the longitudinal portion 120 are internally connected; the pump chamber 500 is disposed within the transverse portion 110; the composite ceramic actuation structure 200 is disposed on both sides of the longitudinal portion 120, so that the pump chamber 500, the mounting bracket, and the composite ceramic actuation structures 200 on both sides together form a sealed space; the inlet check valve 300 and the outlet check valve 400 are connected to the pump chamber 500 and are respectively disposed on both sides of the bottom of the pump chamber 500.

[0048] In this embodiment, the driving force is improved by using a composite ceramic actuation structure 200. The mechanical deformation is converted into a volume change of the pump chamber 500 by utilizing the pre-bent thin film component 210 in the composite ceramic actuation structure 200. In use, the liquid flow rate of the two one-way valves can be precisely controlled by controlling the actuation frequency of the composite ceramic actuation structure 200. This solves the problem that existing piezoelectric drives mostly use cantilever beam structures, which have insufficient driving force and large flow fluctuations. The performance simulation of the microfluidic pump in this application is shown in Appendix Table 2.

[0049] In a preferred embodiment, the pump chamber 500 includes a pump chamber diaphragm 510; the pump chamber diaphragm 510 is disposed on the side of the pump chamber 500 facing the enclosed space.

[0050] In this embodiment, a piezoelectric deformation driving method is employed. An alternating voltage is applied to cause periodic deformation (5-100 μm displacement) in the composite ceramic actuation structure 200, thereby changing the volume of the pump chamber 500. The mechanical deformation is converted into deformation of the pump chamber membrane 510 through a pre-bent membrane structure, thus causing a change in the volume of the pump chamber 500 (volume change rate > 15%). One-way valve control: A umbrella-shaped valve is used to achieve unidirectional fluid delivery (opening / closing response time < 1 ms).

[0051] In this embodiment, the composite ceramic actuation structure 200 achieves efficient energy conversion through mechanical coupling. The one-way valve uses an umbrella-shaped valve to achieve unidirectional liquid transport.

[0052] In a preferred embodiment, the composite ceramic actuation structure 200 includes a piezoelectric ceramic stack structure 220 and a pre-bent thin film assembly 210; the pre-bent thin film assembly 210 is disposed on a T-shaped fixing frame to form a sealed space; the piezoelectric ceramic stack structure 220 is disposed outside the pre-bent thin film assembly 210, and the center point of the pre-bent thin film assembly 210 is bonded to the center point of the piezoelectric ceramic stack structure 220.

[0053] In a preferred embodiment, the piezoelectric ceramic stack structure 220 includes multiple layers of arc-shaped ceramic sheets and an insulating layer; the insulating layer is disposed between the arc-shaped ceramic sheets for insulation.

[0054] In a preferred embodiment, the pre-bent film assembly 210 includes a pre-bent metal sheet and a sealing film; the sealing film is disposed inside the pre-bent metal sheet.

[0055] In a preferred embodiment, the number of arc-shaped ceramic sheets is three, and the insulating layer is made of epoxy resin material.

[0056] In a preferred embodiment, the sealing film is made of polyimide.

[0057] In a preferred embodiment, the thickness of the arc-shaped ceramic sheet is within 0.1-0.5 mm.

[0058] In a preferred embodiment, the thickness of the pre-bent metal sheet is within 70-100 μm, and the thickness of the sealing film is within 10-30 μm.

[0059] In a preferred embodiment, the radius of curvature of the pre-bent film assembly 210 is within 10-20 mm.

[0060] In this embodiment, the design parameters are shown in Appendix Table 1, and the material selection for the arc-shaped ceramic sheet is: PZT-5H (high voltage coefficient d). 33 =650×10 -12m / V); Stacking method: 3 layers of piezoelectric ceramic sheets (single layer thickness 0.2mm) are alternately stacked with epoxy resin, the electrodes adopt an interdigitated layout (to reduce internal resistance), polarization direction: polarized along the thickness direction (Z axis), and the response electric field direction is consistent with the polarization direction.

[0061] The pre-bent metal sheet of the pre-bent film assembly 210 is located on the outer layer and is made of 316L stainless steel with a thickness of 50μm; the sealing film is located on the inner layer and is made of polyimide with a thickness of 20μm. The initial curvature is a spherical pre-bent with a radius of R = 15mm (achieved through thermoforming process).

[0062] Boundary constraints of the pre-bent thin film assembly 210: It is fixed to the T-shaped bracket of the pump body by laser welding on all four sides, and the center point is connected to the center of the composite ceramic actuation structure 200.

[0063] The umbrella-shaped one-way valve features a parabolic surface curvature (radius of curvature R = 2D, where D is the flow channel diameter) and a support rib layout of three spiral radial reinforcing ribs (80μm wide, 30μm high) to enhance anti-reverse rotation capability. Dynamic counterweighting is achieved by adding platinum microspheres (100μm diameter, 0.5mg mass) to the valve edge to reduce high-frequency vibration noise.

[0064] In this embodiment, the microfluidic pump is based on a motion actuator with a multi-layer composite pressure point ceramic structure. The vibration driven by the piezoelectric ceramic is transmitted to the pump chamber diaphragm 510. The pump chamber diaphragm 510 is displaced by the driving force of the piezoelectric ceramic, causing the pump chamber diaphragm 510 to be pressed down. Through the one-way valves set near the inlet and outlet, the medicine liquid siphoned in and stored in the diaphragm medicine pool is pushed towards the outlet. The deformation of the multi-layer piezoelectric ceramic can realize the reset function, and the pump diaphragm opens, so as to continue to draw water into the inlet. This process is repeated to achieve the purpose of continuous infusion of medicine liquid.

[0065] The microfluidic pump workflow in this embodiment is as follows:

[0066] Drive phase: Apply positive voltage → the arc-shaped piezoelectric ceramic sheet contracts → the pump chamber diaphragm 510 bulges upward → the pump chamber 500 volume increases → the inlet valve opens to draw in fluid;

[0067] Discharge stage: Voltage removed → Arc-shaped piezoelectric ceramic sheet reset → Pump chamber diaphragm 510 pressed down → Pump chamber 500 volume decreases → Outlet valve opens to discharge fluid;

[0068] Frequency control: Precise flow control is achieved by adjusting the drive voltage frequency (10-1000Hz).

[0069] In practice, Phase 1: Voltage application (driving phase)

[0070] A +150V pulse voltage is applied to the piezoelectric stack, generating longitudinal strain (ΔL = 48μm).

[0071] The stacking elongates upwards, pushing the center point of the pre-bent film to produce a secondary deformation amplification (the radius of curvature of the film decreases to R' = 10 mm);

[0072] The pump chamber expands by ΔV = 18 μL in 500 cubic meters (35% improvement over traditional flat sheet films).

[0073] Phase 2: Voltage Release (Reset Phase)

[0074] When the voltage returns to zero, the piezoelectric stack contracts and resets, and the pre-bent film quickly recovers its initial curvature by relying on its elastic potential energy.

[0075] The pump chamber is compressed to a volume of 500, generating a double-acting thrust (piezoelectric contraction force + film rebound force).

[0076] Appendix 1

[0077]

[0078] Appendix 2

[0079] index Traditional single-layer piezoelectric drive Composite drive structure Increase Single trip flow 0.8μL / stroke 1.1 μL / stroke +37.5％ Energy conversion efficiency 42％ 68％ +61.9％ Maximum back pressure capability 3.2 kPa 5.6 kPa +75％ Lifespan (number of cycles) <![CDATA[1×10 7 Next <![CDATA[3×10 7 Next +200％

[0080] Formula and analysis for calculating the amplitude of multilayer piezoelectric ceramic stacks

[0081] 1. Derivation of basic formulas

[0082] The displacement (amplitude) of a multilayer piezoelectric stack is mainly determined by the inverse piezoelectric effect and mechanical coupling, and its basic theoretical formula is as follows:

[0083]

[0084] Parameter description:

[0085] ΔL: Total displacement (m)

[0086] n: number of piezoelectric ceramic layers, d33: piezoelectric constant (m / V), E: electric field strength (V / m), V: driving voltage (V), t single layer: thickness of a single piezoelectric ceramic layer (m).

[0087] Example calculation:

[0088] If n = 3, d33 = 650 × 10⁻¹² m / V, V = 150 V, t_single_layer = 0.2 × 10⁻³ m.

[0089] ΔL=10×650×10-12×1500.2×10-3=10×650×10-12×7.5×105=48.75μmΔL=10×650×10-12×0.2×10-3150=10×650×10-12×7.5×105=48.75μm

[0090] (Note: This result represents the free displacement under ideal no-load conditions)

[0091] 2. Actual operating condition correction model

[0092] In practical applications, piezoelectric stacks are affected by the load stiffness kload and their own stiffness kpzt, so a displacement attenuation factor needs to be introduced:

[0093]

[0094] Key parameter calculation:

[0095] Piezoelectric stacking stiffness:

[0096] Kpzt is affected by A: the cross-sectional area of ​​the single-layer piezoelectric ceramic (m²) 2 Yeff: The effect of equivalent Young's modulus (PZT-5H is approximately 60 GPa) on load stiffness (such as pre-bent membranes).

[0097]

[0098] Efilm: elastic modulus of film (e.g., 193 GPa for stainless steel 316L), tfilm: film thickness (m), R: radius of curvature of film (m), ν: Poisson's ratio (0.3 for stainless steel).

[0099] 3 Dynamic Response Model

[0100] Under high-frequency drive, the influence of the electromechanical coupling resonant frequency on the amplitude must be considered:

[0101]

[0102] meff: Equivalent kinematic mass (piezoelectric stack mass + thin film equivalent mass)

[0103] Amplitude changes with frequency:

[0104]

[0105] ζζ: Damping ratio (usually taken as 0.01 to 0.1)

[0106] 4. Design and optimize parameter table

[0107]

[0108]

[0109] This invention discloses a piezoelectric ceramic microfluidic pump with a composite drive structure. By using a composite ceramic actuation structure 200, the driving force is improved. The mechanical deformation is converted into a volume change in the pump chamber 500 by utilizing the pre-bent diaphragm component 210 in the composite ceramic actuation structure 200. In use, the liquid flow rate of the two one-way valves can be precisely controlled by controlling the actuation frequency of the composite ceramic actuation structure 200. This solves the problems of insufficient driving force and large flow fluctuations in existing piezoelectric drives that mostly use cantilever beam structures.

[0110] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A piezoelectric ceramic micro-pump of a compound driving structure, characterized in that, include: T-shaped mounting bracket; Composite ceramic actuation structure; Pump chamber; Inlet check valve and outlet check valve; The T-shaped fixing frame includes a horizontal part and a vertical part; The transverse portion is internally connected to the longitudinal portion; The pump chamber is disposed within the transverse portion; The composite ceramic actuation structure is disposed on both sides of the longitudinal section, so that the pump chamber, the fixing frame and the composite ceramic actuation structure on both sides together form a closed space; The inlet check valve and the outlet check valve are connected to the pump chamber and are respectively located on both sides of the bottom of the pump chamber.

2. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 1, characterized in that, The reinforcing rib is annular in shape, and the pump chamber includes: Pump chamber membrane; The pump chamber diaphragm is disposed on the side of the pump chamber facing the enclosed space.

3. The piezoelectric ceramic micro-pump of composite driving structure according to claim 2, characterized in that, The composite ceramic actuation structure includes: Piezoelectric ceramic stacked structure; Pre-bent film assembly; The pre-bent film assembly is mounted on the T-shaped fixing frame to form the sealed space; The piezoelectric ceramic stack structure is disposed on the outside of the pre-bent film assembly, and the center point of the pre-bent film assembly is bonded to the center point of the piezoelectric ceramic stack structure.

4. The piezoelectric ceramic micro-pump of composite driving structure according to claim 3, characterized in that, The piezoelectric ceramic stack structure includes: Multi-layered curved ceramic sheet; Insulating layer; The insulating layer is disposed between the arc-shaped ceramic sheets for insulation.

5. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 3, characterized in that, The pre-bent film assembly includes: Pre-bent metal sheet; Sealed film; The sealing film is disposed on the inside of the pre-bent metal.

6. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 4, characterized in that, The number of arc-shaped ceramic sheets is 3 layers, and the insulating layer is made of epoxy resin material.

7. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 5, characterized in that, The sealed film is made of polyimide.

8. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 6, characterized in that, The thickness of the arc-shaped ceramic sheet is within 0.1-0.5 mm.

9. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 7, characterized in that, The thickness of the pre-bent metal sheet is within 70-100 μm, and the thickness of the sealing film is within 10-30 μm.

10. The piezoelectric ceramic micro-pump of the composite driving structure according to claim 7, characterized in that, The radius of curvature of the pre-bent film assembly is within 10-20 mm.

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