Piezoelectric ceramic micropump

Abstract

The application discloses a piezoelectric ceramic micro-pump, which comprises a piezoelectric ceramic layer, a top glass layer, a middle silicon layer and a bottom glass layer, wherein the piezoelectric ceramic layer, the top glass layer, the middle silicon layer and the bottom glass layer are sequentially arranged from top to bottom; the piezoelectric ceramic layer adopts a lead zirconate titanate (PZT) film, and a pump cavity diaphragm is driven to produce reciprocating deformation through a reverse piezoelectric effect; the middle silicon layer is integrated with the pump cavity, a liquid inlet valve, a liquid outlet valve and a flow channel, and is formed by monocrystalline silicon integrated deep etching; the top glass layer and the bottom glass layer are both borosilicate glass, and form a gas-tight sealed cavity through anode bonding with the middle silicon layer. The piezoelectric ceramic micro-pump adopts a direct pumping structure, completely cancels a hydraulic coupling intermediate layer, has no hydraulic medium temperature drift and parasitic flow, the driving efficiency is improved to more than 85%, and the dose precision is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic micropump technology, specifically a piezoelectric ceramic micropump. Background Technology

[0002] Current mainstream insulin pumps (using indirect drive methods such as motors and shape memory alloys) suffer from the following limitations: Their complex structure makes miniaturization difficult; indirect drive relies on the precision assembly of multiple components such as motors, lead screws, and springs, resulting in a large and heavy overall size, hindering truly thin and lightweight application; control precision and response speed are limited, as mechanical backlash, friction, and inertia in the transmission links introduce errors, affecting the accuracy and real-time delivery of micro-volume insulin (e.g., 0.05U); reliability and lifespan face challenges, with more moving parts meaning higher wear, failure risk, and more complex maintenance; costs remain high, with the processing, assembly, and reliance on imports of precision mechanical parts driving up manufacturing costs; and energy consumption is relatively high, as mechanical transmission efficiency is lower than the direct electrical-to-mechanical energy conversion of piezoelectric ceramics. These factors collectively constrain the development of insulin pumps towards smaller size, higher precision, longer battery life, and lower cost.

[0003] In current mainstream MEMS micropump technology, a "hydraulic coupling" structure is commonly used to isolate the piezoelectric drive component from direct contact with the liquid. This structure introduces a hydraulic chamber filled with a medium liquid (usually mineral oil or deionized water) between the drive diaphragm and the liquid, and the liquid transmits pressure to drive the flow of the liquid. Suzhou In-Situ Technology's representative products adopt this architecture.

[0004] However, the hydraulic coupling structure has three systemic defects: First, the hydraulic chamber itself introduces a large dead volume, generally in the range of 50μL to 100μL, which makes the proportion of drug solution that can be effectively output with each drive extremely low, resulting in amplified infusion dosage error; Second, there is a difference in the coefficient of thermal expansion between the hydraulic medium and the drug solution. In wearable application scenarios, the alternating changes in body temperature and ambient temperature will cause passive changes in the volume of the hydraulic chamber, generating parasitic flow and interfering with dosage accuracy; Third, it directly blocks the path of monolithic integration of the device and the CMOS sensing circuit, increasing system complexity and cost. Summary of the Invention

[0005] The purpose of this invention is to provide a piezoelectric ceramic micropump to solve the problems in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a piezoelectric ceramic micropump, comprising a piezoelectric ceramic layer, a top glass layer, a middle silicon layer and a bottom glass layer, wherein the piezoelectric ceramic layer, the top glass layer, the middle silicon layer and the bottom glass layer are arranged sequentially from top to bottom;

[0007] The piezoelectric ceramic layer is made of lead zirconate titanate (PZT) thin film, which drives the pump chamber diaphragm to generate reciprocating deformation through the inverse piezoelectric effect.

[0008] The intermediate silicon layer integrates a pump chamber, an inlet valve, an outlet valve, and a flow channel, and is formed by deep etching of monocrystalline silicon.

[0009] Both the top and bottom glass layers are borosilicate glass, which are bonded to the middle silicon layer by anodizing to form an airtight sealed cavity.

[0010] Preferably, the piezoelectric ceramic layer is a composite membrane structure consisting of a central island and a ring-shaped support.

[0011] Preferably, the drug contact surface of the intermediate silicon layer is deposited with a silicon nitride coating, the thickness of which is 100~300nm, and the silicon nitride coating is prepared by LPCVD process.

[0012] Preferably, both the inlet valve and the outlet valve are made of monocrystalline silicon solid-state micro-valve without polymer elastomers, forming redundant protection in conjunction with a passive flow resistance valve; the flow channel is modified with hydrophilicity to make the contact angle <10°.

[0013] Preferably, the pump chamber has a shallow, flattened structure.

[0014] Preferably, the piezoresistive sensing array is natively integrated on the back side of the intermediate silicon layer and co-packaged with the piezoelectric driving unit.

[0015] Preferably, the bottom glass layer has a liquid inlet and a liquid outlet.

[0016] A piezoelectric ceramic micropump is used for high-precision quantitative delivery of insulin, reagents or high-viscosity liquids, and is particularly suitable for patch-type insulin pumps and closed-loop artificial pancreas systems.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. Adopting a direct pumping architecture, the hydraulic coupling intermediate layer is completely eliminated, eliminating hydraulic medium temperature drift and parasitic flow, increasing the driving efficiency to over 85%, and significantly improving dosage accuracy.

[0019] 2. A 100-300nm silicon nitride coating is deposited in the contact area between the piezoelectric ceramic membrane and the drug solution. It has strong chemical inertness and meets the standards for biocompatibility, avoiding drug solution denaturation, adsorption and material corrosion, and meeting medical safety requirements.

[0020] 3. The intermediate silicon layer is formed by deep etching of monocrystalline silicon, integrating the pump chamber, solid micro valve and flow channel. It has no polymer elastomer, making the structure more reliable and the life of the machine longer. The thickness of the whole machine is less than 2.6mm and the weight is only 2g, achieving ultra-thinness.

[0021] 4. The flow channel is modified with hydrophilic properties, and the pump chamber adopts a shallow and flat design with a dead volume of less than 50μL and extremely low liquid residue, which greatly improves the accuracy and stability of micro-infusion.

[0022] 5. It adopts piezoelectric drive with no mechanical rotating and friction parts, with working noise below 30dB, power consumption as low as 10mW, significantly extended battery life, and quieter and more comfortable to wear.

[0023] 6. The intermediate silicon layer can natively integrate a sensor array, is compatible with CMOS circuits, and realizes pump-sensor integrated packaging, providing a hardware foundation for a closed-loop artificial pancreas system. Attached Figure Description

[0024] 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:

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a side view of the present invention;

[0027] Figure 3 This is the present invention. Figure 2 Sectional view of AA;

[0028] Figure 4 This is the front view of the present invention;

[0029] Figure 5 This is the present invention. Figure 4 Sectional view of BB;

[0030] Figure 6 This is a schematic diagram of the structure of the middle silicon layer and the bottom glass layer of the present invention.

[0031] In the diagram: 1. Piezoelectric ceramic layer; 2. Top glass layer; 3. Middle silicon layer; 4. Bottom glass layer. Detailed Implementation

[0032] 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.

[0033] Please see Figure 1-6 In this embodiment of the invention, a piezoelectric ceramic micropump includes a piezoelectric ceramic layer 1, a top glass layer 2, a middle silicon layer 3, and a bottom glass layer 4, wherein the piezoelectric ceramic layer 1, the top glass layer 2, the middle silicon layer 3, and the bottom glass layer 4 are arranged sequentially from top to bottom.

[0034] The piezoelectric ceramic layer 1 is made of lead zirconate titanate (PZT) thin film, which drives the pump chamber diaphragm to generate reciprocating deformation through the inverse piezoelectric effect.

[0035] The intermediate silicon layer 3 integrates a pump chamber, an inlet valve, an outlet valve, and a flow channel, and is formed by deep etching of monocrystalline silicon.

[0036] Both the top glass layer 2 and the bottom glass layer 4 are borosilicate glass, which are bonded to the intermediate silicon layer 3 to form an airtight sealed cavity. The bottom glass layer 4 has a liquid inlet and a liquid outlet.

[0037] The piezoelectric ceramic layer 1 is a composite membrane structure consisting of a central island and a ring support.

[0038] The intermediate silicon layer 3 has a silicon nitride coating (Si3N4) deposited on its liquid contact surface. The thickness of the silicon nitride coating is 100~300nm, and the silicon nitride coating is prepared by LPCVD process.

[0039] Both the inlet and outlet valves are made of monocrystalline silicon solid-state micro-valve, without polymer elastomers, forming redundant protection in conjunction with passive flow resistance valves; the flow channel is modified with hydrophilicity to ensure a contact angle of <10°. The pump chamber has a shallow, flattened structure.

[0040] The piezoresistive sensing array is natively integrated on the back of the intermediate silicon layer 3 and is co-packaged with the piezoelectric drive unit.

[0041] Employing a direct pumping architecture, this device completely eliminates the hydraulic coupling intermediate layer, removing hydraulic medium temperature drift and parasitic flow, thus increasing drive efficiency to over 85% and significantly improving dosage accuracy. A 100-300nm silicon nitride coating is deposited on the piezoelectric ceramic membrane in contact with the drug solution, ensuring strong chemical inertness and biocompatibility, preventing drug denaturation, adsorption, and material corrosion, meeting medical safety requirements. The intermediate silicon layer 3 is formed using monocrystalline silicon through deep etching, integrating the pump chamber, solid-state micro-valve, and flow channel. It eliminates polymer elastomers, resulting in a more reliable structure and longer lifespan. The entire device is less than 2.6mm thick and weighs only 2g, achieving ultra-thin and lightweight design. The flow channel is hydrophilically modified, and the pump chamber features a shallow, flat design with a dead volume of less than 50μL, resulting in extremely low liquid residue and significantly improving the accuracy and stability of micro-infusion. Using piezoelectric drive with no mechanical rotating or friction components, the operating noise is below 30dB, power consumption is as low as 10mW, significantly extending battery life and making it quieter and more comfortable to wear.

[0042] The intermediate silicon layer 3 can natively integrate a sensor array, is compatible with CMOS circuits, and realizes pump-sensor integrated packaging, providing a hardware foundation for a closed-loop artificial pancreas system.

[0043] The piezoelectrically driven diaphragm is in direct contact with the liquid medicine, without any coupling medium such as hydraulic oil or buffer solution. The displacement of the piezoelectric diaphragm is directly and losslessly converted into liquid medicine output, with no temperature drift, no parasitic flow, and no dead volume amplification.

[0044] The top glass layer 2, the middle silicon layer 3, and the bottom glass layer 4 are bonded together to form an atomically airtight seal; the surface in contact with the drug solution is covered with a silicon nitride Si3N4 coating to achieve insulation, corrosion resistance, and high biocompatibility, avoiding drug solution degradation and material corrosion.

[0045] The piezoelectric diaphragm employs a central island and ring-shaped support composite structure, combined with digital drive waveforms and hysteresis compensation algorithms, to achieve sub-micron level stroke control, ensuring precise and stable single-pump volume. Hydrophilic modification of the flow channel and shallow cavity design reduce liquid residue and improve infusion accuracy.

[0046] A piezoelectric ceramic micropump is used for high-precision quantitative delivery of insulin, reagents or high-viscosity liquids, and is particularly suitable for patch-type insulin pumps and closed-loop artificial pancreas systems.

[0047] The working principle of this invention is as follows: A programmable driving voltage is applied to the piezoelectric ceramic layer 1 (PZT thin film), utilizing the inverse piezoelectric effect to cause controllable reciprocating micro-deformation of the piezoelectric film, driving the pump chamber diaphragm to move synchronously up and down, periodically changing the internal volume of the pump chamber. Upward deformation of the piezoelectric film → the pump chamber volume increases, creating a negative pressure inside → the inlet valve opens, the outlet valve closes → the medicine is drawn into the pump chamber from the inlet of the bottom glass layer 4. Downward deformation of the piezoelectric film → the pump chamber volume decreases, the internal pressure increases → the inlet valve closes, the outlet valve opens → the medicine is directionally discharged from the outlet, completing one precise infusion cycle.

[0048] The piezoelectrically driven diaphragm is in direct contact with the liquid medicine, without any coupling medium such as hydraulic oil or buffer solution. The displacement of the piezoelectric diaphragm is directly and losslessly converted into liquid medicine output, with no temperature drift, no parasitic flow, and no dead volume amplification.

[0049] The top glass layer 2, the middle silicon layer 3, and the bottom glass layer 4 are bonded together to form an atomically airtight seal; the surface in contact with the drug solution is covered with a silicon nitride Si3N4 coating to achieve insulation, corrosion resistance, and high biocompatibility, avoiding drug solution degradation and material corrosion.

[0050] The piezoelectric membrane adopts a central island and ring support composite structure, combined with digital drive waveform and hysteresis compensation algorithm, to achieve submicron-level stroke control and ensure accurate and stable single pumping volume; hydrophilic modification of the flow channel and shallow cavity design reduce liquid residue and improve infusion accuracy.

[0051] 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. The device comprises a piezoelectric ceramic layer (1), a top glass layer (2), a middle silicon layer (3), and a bottom glass layer (4), wherein the piezoelectric ceramic layer (1), the top glass layer (2), the middle silicon layer (3), and the bottom glass layer (4) are arranged sequentially from top to bottom; The piezoelectric ceramic layer (1) is made of lead zirconate titanate (PZT) film, which drives the pump chamber diaphragm to generate reciprocating deformation through the inverse piezoelectric effect; The intermediate silicon layer (3) integrates a pump chamber, an inlet valve, an outlet valve, and a flow channel, and is formed by deep etching of monocrystalline silicon. The top glass layer (2) and the bottom glass layer (4) are both borosilicate glass, which are bonded to the middle silicon layer (3) to form an airtight sealed cavity.

2. The piezoelectric ceramic micropump according to claim 1, characterized in that: The piezoelectric ceramic layer (1) is a composite membrane structure consisting of a central island and a ring support.

3. The piezoelectric ceramic micropump according to claim 1, characterized in that: The intermediate silicon layer (3) has a silicon nitride coating deposited on the drug contact surface. The thickness of the silicon nitride coating is 100~300nm and the silicon nitride coating is prepared by LPCVD process.

4. The piezoelectric ceramic micropump according to claim 1, characterized in that: Both the inlet and outlet valves are made of monocrystalline silicon solid-state micro-valve without polymer elastomers, forming redundant protection in conjunction with passive flow resistance valves; the flow channel is modified with hydrophilicity to make the contact angle <10°.

5. The piezoelectric ceramic micropump according to claim 1, characterized in that: The pump chamber has a shallow, flattened structure.

6. The piezoelectric ceramic micropump according to claim 1, characterized in that: The intermediate silicon layer (3) has a natively integrated piezoresistive sensing array on its back side, which is co-packaged with the piezoelectric drive unit.

7. A piezoelectric ceramic micropump according to claim 1, characterized in that: The bottom glass layer (4) has an inlet and an outlet.

8. A piezoelectric ceramic micropump according to any one of claims 1-7 is used for high-precision quantitative delivery of insulin, reagents or high-viscosity liquids, and is particularly suitable for patch-type insulin pumps and closed-loop artificial pancreas systems.

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