A piezoelectric-driven microfluidic droplet controllable generation device and method

Abstract

This invention discloses a piezoelectric-driven microfluidic droplet controllable generation device and method. The device includes: a fixed support module, a piezoelectric driving module, a chip clamping mechanism, a microfluidic chip module, a support stage, a fluid delivery system, a control module, and a displacement adjustment module. This invention achieves on-demand droplet generation through precise control of pulse signals. Combined with automated control logic, it significantly improves the stability and experimental efficiency of droplet generation. The microfluidic chip module adopts a standardized appearance design with uniform size, shape, and interface specifications. It adapts to different experimental needs only through differentiated internal microchannels, enabling rapid chip replacement, reducing operational complexity, and further optimizing the experimental process.

Description

Technical Field

[0001] This invention belongs to the field of microfluidics technology, specifically relating to a microfluidic droplet controllable generation device and method based on piezoelectric drive. Background Technology

[0002] Printed electronics demands extremely high printing quality and resolution. Precise microfluidic droplet generation is crucial for ensuring device performance, but existing technologies have several shortcomings and require optimization. Current microfluidic droplet generation methods suitable for printed electronics are mainly divided into passive and active types. Passive methods (such as T-channel methods, flow focusing methods, and coaxial flow methods) rely on fluid shear force and interfacial tension, requiring no external energy input. However, they suffer from poor droplet size uniformity, low generation frequency, and high processing precision requirements, failing to meet the high-resolution demands of printed electronics. Active methods, while offering greater controllability, involve complex and expensive equipment, making them unsuitable for actual printed electronics production scenarios. Most existing droplet generation devices rely on high-precision injection pumps, lacking flexibility and limited to laboratory and fixed equipment environments. A few devices relying on gravity flow are limited in form, efficiency, and success rate, failing to meet the precision printing requirements of printed electronics.

[0003] Therefore, to address the above shortcomings, there is a need to provide a microfluidic chip droplet generation device that can achieve precise and controllable droplet generation, simplify the structure and reduce costs, while also possessing good operational convenience, thus improving operational ease of use and scenario adaptability. Summary of the Invention

[0004] To address the issues of poor droplet size uniformity and low generation frequency in existing microfluidic droplet generation devices, passive generation methods suffer from poor droplet size uniformity, while active generation methods are prone to...

[0005] To address the issues of material loss and the complexity and expense of equipment, and to resolve the shortcomings of existing devices—such as reliance on fixed precision laboratory equipment leading to insufficient flexibility, and the limited range of single-form, low-efficiency, and low-success-rate devices without fixed equipment, as well as insufficient positioning accuracy of chips and drive modules and poor ease of operation—this paper proposes a piezoelectric-driven microfluidic droplet controllable generation device. This device aims to achieve precise, stable, and controllable generation of microfluidic droplets, optimize the device's structural adaptability and ease of operation, improve the positioning accuracy of chips and piezoelectric drive modules, reduce the device's dependence on fixed experimental conditions, and adapt to the droplet generation experimental technology requirements of microfluidic inkjet printing in printed electronics.

[0006] The technical solution adopted in this invention is as follows:

[0007] The present invention provides a microfluidic droplet controllable generating device based on piezoelectric drive, comprising: a fixed support module (1), a piezoelectric drive module (2), a chip clamping mechanism (3), a microfluidic chip module (6), a support platform (7), a fluid delivery system, a control module (13), and a displacement adjustment module;

[0008] The fixed support module (1) is equipped with the displacement adjustment module; the displacement adjustment module is used to adjust the position of the piezoelectric drive module (2) in the XY plane and the position of the microfluidic chip module (6) held by the chip clamping mechanism (3) along the Z direction, so that the signal output area of ​​the piezoelectric drive module (2) is aligned with the fluid output port of the microfluidic chip module (6);

[0009] The fluid delivery system is connected to two fluid input ports of the microfluidic chip module (6) respectively, and is used to deliver two immiscible liquids to the microfluidic chip module (6). The two liquids are mixed through the microchannel of the microfluidic chip module (6). Under the pulse pressure of the piezoelectric drive module (2), combined with fluid shear force and interfacial tension, the mixed liquid forms monodisperse droplets in the microchannel.

[0010] The support platform (7) is located below the microfluidic chip module (6) and is used to receive the monodisperse droplets dripping from the fluid output port of the microfluidic chip module (6).

[0011] The control module (13) is connected to the piezoelectric drive module (2) and the displacement adjustment module, and is used to control the piezoelectric drive module (2) and the displacement adjustment module.

[0012] Furthermore, the displacement adjustment module includes an X-axis displacement adjustment module, a Y-axis displacement adjustment module, and a Z-axis displacement adjustment module;

[0013] The Z-direction displacement adjustment module is located on the rear side of the fixed support module (1), and the microfluidic chip module (6) is clamped and fixed by the chip clamping mechanism (3) on the inner side of the Z-direction displacement adjustment module. Under the drive of the Z-direction displacement adjustment module, the position of the microfluidic chip module (6) along the Z direction is adjusted. The Y-direction displacement adjustment module is symmetrically arranged on the left and right sides of the fixed support module (1) along the Y direction. The X-direction displacement adjustment module is arranged on the top of the Y-direction displacement adjustment modules on both sides along the X direction. Under the drive of the Y-direction displacement adjustment module, the X-direction displacement adjustment module is moved along the Y direction. The piezoelectric drive module (2) is arranged on the top of the X-direction displacement adjustment module, and the piezoelectric drive module (2) is moved along the X direction.

[0014] Furthermore, the X-axis displacement adjustment module adopts an X-axis linear motor fine-tuning platform (8); the Y-axis displacement adjustment module includes a Y-axis fine-tuning platform (10) and a Y-axis linear motor (11); the Y-axis linear motor (11) drives the Y-axis fine-tuning platform (10) to move along the Y direction; the Z-axis displacement adjustment module includes a Z-axis fine-tuning platform (4) and a Z-axis linear motor (5); the Z-axis linear motor (5) drives the Z-axis fine-tuning platform (4) to move along the Z direction; wherein, the Y-axis fine-tuning platform (10) and the Z-axis fine-tuning platform (4) both adopt a structure of precision lead screw module, guide rail and connecting fastener (12); and are fixed to the fixed support module (1) through the connecting fastener (12).

[0015] Furthermore, the piezoelectric drive module (2) includes a signal generator, a drive signal adapter module, a piezoelectric stack, and an actuator clamp (14); the piezoelectric stack is clamped and fixed by the actuator clamp (14); the drive waveform output by the signal generator is applied to the piezoelectric stack after passing through the drive signal adapter module; the piezoelectric stack is composed of multiple piezoelectric sheets stacked together, and converts the electrical signal into precise mechanical displacement through the inverse piezoelectric effect, which acts on the fluid to generate droplets.

[0016] Furthermore, the actuator clamp (14) adopts a symmetrical semi-circular clamping arm structure to disperse the clamping shear force on the piezoelectric stack and avoid damage to the surface of the piezoelectric stack; the actuator clamp (14) includes an actuator fixing base (14-1) and a pre-tightening adjustment clamp (14-2).

[0017] The actuator mounting base (14-1) is fixed to the X-direction displacement adjustment module through a standard mounting hole, and a first semi-circular groove is provided in the middle along the Y direction;

[0018] The pre-tightening adjustment clamp (14-2) is fixed above the actuator fixing base (14-1) by pre-tightening adjustment bolts, and a second semi-circular groove symmetrical to the first semi-circular groove is provided.

[0019] The first semi-circular groove and the second semi-circular groove together form a clamping surface for accommodating and holding the piezoelectric stack.

[0020] Furthermore, the chip clamping mechanism (3) includes elastic grippers (3-1), profile base (3-2), fixed end plate (3-3), butterfly knob (3-4), bidirectional adjusting screw (3-5), and internal hexagon (3-6).

[0021] The fixed end plates (3-3) are symmetrically fixed on the left and right sides of the profile base (3-2); the bidirectional adjusting screw (3-5) passes through the left and right sides of the profile base (3-2), and the butterfly knobs (3-4) are fixed at both ends; the bidirectional adjusting screw (3-5) is controlled to rotate by the butterfly knobs (3-4) on both sides; the elastic claws (3-1) are symmetrically installed on the left and right sides of the bidirectional adjusting screw (3-5), and under the action of the bidirectional adjusting screw (3-5), the two... The elastic grippers (3-1) on both sides move in opposite directions; the microfluidic chip module (6) is disposed between the elastic grippers (3-1) on both sides; wherein, each elastic gripper (3-1) on one side has a groove on the side facing the microfluidic chip module (6) to ensure that the microfluidic chip module (6) is clamped firmly and without causing squeezing damage; each elastic gripper (3-1) on one side is provided with an internal hexagon (3-6) for adjusting the size of the elastic gripper (3-1).

[0022] Furthermore, the microfluidic chip module (6) includes a microfluidic chip substrate, inside which there are T-shaped microchannels, including a vertical microchannel and a horizontal microchannel that intersects with the middle of the vertical microchannel; the upper and lower ends of the vertical microchannel are a continuous phase inlet (6-1) and an outlet (6-3), respectively; one end of the horizontal microchannel is a dispersed phase inlet (6-4), and the other end intersects with the vertical microchannel, which is called the flow path intersection point (6-2).

[0023] The present invention also provides a method for a piezoelectrically driven microfluidic droplet controllable generation device, comprising the following steps:

[0024] Step S1: With the programmable control unit as the core, the drive voltage, drive frequency, continuous phase fluid flow rate and dispersed phase fluid flow rate of the piezoelectric stack of the piezoelectric drive module are set in collaboration between the host computer and the control module (13).

[0025] Step S2: Under the action of the displacement adjustment module, adjust the Z-axis height of the microfluidic chip module (6) and adjust the X-axis and Y-axis positions of the piezoelectric drive module (2) so that the signal output area of ​​the piezoelectric drive module (2) is aligned with the liquid outlet (6-3) area of ​​the microfluidic chip module (6);

[0026] Step S3: Start the signal generator and fluid delivery system of the piezoelectric drive module;

[0027] The fluid delivery system independently controls the flow rates of the continuous phase fluid and the dispersed phase fluid, delivering the two immiscible fluids to the microchannel of the microfluidic chip module (6) at a set constant flow rate. The flow rate of the dispersed phase fluid is controlled at 0.1–5 μL / min, the flow rate of the continuous phase fluid is controlled at 1–20 μL / min, and the flow rate ratio of the two phase fluids is maintained in the range of 1:5 to 1:10.

[0028] The signal generator outputs a rectangular wave drive signal with a specified drive voltage amplitude, drive frequency, and duty cycle as pulse excitation; wherein, the drive voltage amplitude is set to 0–100V, the drive frequency is adjustable in the range of 1Hz–5kHz, and the duty cycle is set to 30%–70%;

[0029] After receiving the rectangular wave drive signal, the piezoelectric stack efficiently converts electrical energy into periodic mechanical displacement based on the inverse piezoelectric effect. This generates high-frequency, low-amplitude mechanical vibrations in the local area of ​​the microfluidic chip module (6), which are further converted into pulsed pressure fields acting on the fluid. This enables active control of the fluid interface and provides a key power source for the precise droplet drop. The two-phase fluids undergo shear focusing and droplet generation, shearing and necking fracture to form independent droplets, which finally drip from the outlet (6-3) of the microfluidic chip module (6).

[0030] Furthermore, the droplet generation process is as follows:

[0031] A1, Introduction of two-phase fluid:

[0032] Continuous phase fluid: Injected from the continuous phase inlet (6-1), flows vertically downward along the microchannel, and flows perpendicularly to the flow path intersection point (6-2).

[0033] Dispersed phase fluid: Injected horizontally into the dispersed phase inlet (6-4) of the microchannel, flowing horizontally towards the flow path junction (6-2).

[0034] A2, Shear Focusing and Liquid Filament Generation:

[0035] At the flow path intersection (6-2), the two-phase fluids interact and generate a liquid filament through shear focusing; specifically, the horizontally flowing dispersed phase fluid is squeezed and constrained by the vertically flowing continuous phase fluid to form an extremely fine liquid filament, a process called fluid shear focusing.

[0036] A3, shearing and necking fracture, generating microdroplets:

[0037] As the flow path converges at (6-2), the continuous phase fluid continues to flow toward the bottom outlet (6-3). The viscous shear force of the continuous phase fluid acts on the liquid filament, causing the liquid filament to neck. When the viscous shear force exceeds the balance between the interfacial tension and viscous resistance of the dispersed phase fluid, the liquid filament will be broken, forming independent microdroplets.

[0038] A4, the generated microdroplets are carried by the continuous phase fluid and continue to flow vertically downwards along the microchannel. At the same time, the microfluidic chip (6) is vibrated regularly by the vibration of the piezoelectric drive module. The outlet (6-3) is hydrophobically treated and finally the monodisperse microdroplets flow out from the outlet (6-3) at the bottom.

[0039] The beneficial effects of this invention are as follows:

[0040] This invention achieves on-demand droplet generation by precisely controlling pulse signals, and combined with automated control logic, significantly improves the stability of droplet generation and experimental efficiency. The microfluidic chip module adopts a standardized appearance design with uniform size, shape and interface specifications. It adapts to different experimental needs only through differentiated internal microchannels, enabling rapid chip replacement, reducing operational complexity and further optimizing the experimental process. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 An overall diagram of the piezoelectrically driven microfluidic droplet controllable generator provided by the present invention;

[0043] Figure 2 A perspective view of the fixed support module provided by the present invention;

[0044] Figure 3 An assembly drawing of the actuator fixture and piezoelectric stack provided by the present invention;

[0045] Figure 4 A perspective view of the actuator fixture provided by the present invention;

[0046] Figure 5 An assembly diagram of the piezoelectric stack provided by the present invention in an actuator mounting base;

[0047] Figure 6 A perspective view of the piezoelectric stack provided by the present invention;

[0048] Figure 7This is an assembly diagram of the microfluidic chip module and chip clamping mechanism provided by the present invention;

[0049] Figure 8 A cross-sectional view of the microfluidic chip module provided by the present invention;

[0050] Figure 9 A perspective view of the support platform provided by the present invention;

[0051] Figure 10 This is a microscopic image of the generated microdroplets.

[0052] In the diagram: 1. Fixed support module; 2. Piezoelectric drive module; 3. Chip clamping mechanism; 4. Z-axis fine-tuning platform; 5. Z-axis linear motor; 6. Microfluidic chip module; 7. Support platform; 8. X-axis linear motor fine-tuning platform; 9. Bolt; 10. Y-axis fine-tuning platform; 11. Y-axis linear motor; 12. Connecting fastener; 13. Control module; 14. Actuator clamp; 15. Acrylic plate exhaust port; 3-1. Elastic gripper; 3-2. Profile base; 3-3. Fixed end plate; 3-4. Butterfly knob; 3-5. Bidirectional adjusting screw; 3-6. Hex socket; 6-1. Continuous phase inlet; 6-2. Flow path junction; 6-3. Outlet; 6-4. Dispersed phase inlet; 7-1. Standard mounting hole; 7-2. Mounting ear plate; 7-3. Anti-slip pad; 7-4. Support platform surface; 14-1. Actuator fixed base; 14-2. Pre-tightening adjusting clamp. Detailed Implementation

[0053] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the invention.

[0054] To address the problems of poor controllability, insufficient compatibility, dependence on fixed equipment, and high cost in existing microfluidic chip droplet generation devices, this invention provides a controllable microfluidic droplet generation device based on piezoelectric actuation, such as... Figure 1 As shown, it includes: a fixed support module 1, a piezoelectric drive module 2, a chip clamping mechanism 3, a microfluidic chip module 6, a support platform 7, a fluid delivery system, a control module 13, and a displacement adjustment module;

[0055] The fixed support module 1 is equipped with a displacement adjustment module; the displacement adjustment module is used to adjust the position of the piezoelectric drive module 2 in the XY plane and the position of the microfluidic chip module 6 held by the chip clamping mechanism 3 along the Z direction, so that the signal output area of ​​the piezoelectric drive module 2 is aligned with the fluid output port of the microfluidic chip module 6.

[0056] The fluid delivery system is connected to two fluid input ports of the microfluidic chip module 6, and is used to deliver two immiscible liquids to the microfluidic chip module 6. The two liquids are mixed through the microchannel of the microfluidic chip module 6. Under the pulse pressure of the piezoelectric drive module 2, combined with the fluid shear force and interfacial tension, the mixed liquid forms monodisperse droplets in the microchannel.

[0057] The support platform 7 is located below the microfluidic chip module 6 and is used to receive monodisperse droplets falling from the fluid output port of the microfluidic chip module 6.

[0058] The control module 13 is connected to the piezoelectric drive module 2 and the displacement adjustment module, and is used to control the piezoelectric drive module 2 and the displacement adjustment module.

[0059] The following is a detailed introduction to each major component:

[0060] (a) Fixed support module 1

[0061] See Figure 2 The fixed support module 1 provides a stable foundation for the device, and integrates a displacement adjustment module, a piezoelectric drive module 2, and a fluid transport module, etc. Figure 2 As shown, the fixed support module 1 can use an aluminum alloy base, such as a 4040 aluminum alloy frame. The aluminum alloy base is made of aluminum profiles and is stably spliced ​​by angle brackets, bolts, nuts and washers. T-nuts are used. A vertical aluminum frame is added in the middle to enhance the stability of the Z-axis screw module. It has the advantages of being lightweight, high-strength and corrosion-resistant.

[0062] (ii) Supporting platform 7

[0063] See Figure 9 The support platform 7, with a frame structure and built-in connecting wires, standard parts, and other auxiliary components, is installed below the rear side of the fixed support module 1. Its symmetrical mechanical design ensures a flat and stable support surface. Mounting lugs and standard mounting holes are provided on both sides, allowing it to be fixed to the aluminum alloy base with bolts 9. It is used to store the generated droplets, ensuring experimental integrity. Specifically, the support platform 7 includes: a support platform surface 7-4, mounting lugs 7-2, and anti-slip pads 7-3. The support platform surface 7-4 is flat and stable, and its symmetrical mechanical design ensures stability after placing the vessel. The mounting lugs 7-2 have standard mounting holes 7-1 and are fixed to the aluminum alloy frame with bolts to prevent platform displacement during the experiment. The anti-slip pads 7-3 are attached to the support platform surface 7-4 to prevent the vessel from sliding and provide reliable support for droplet collection.

[0064] (III) Displacement Adjustment Module

[0065] The displacement adjustment module includes an X-axis displacement adjustment module, a Y-axis displacement adjustment module, and a Z-axis displacement adjustment module. The adjustment accuracy of the displacement adjustment module reaches 10 micrometers, and precise contact between the piezoelectric drive module 2 and the microfluidic chip module 6 is achieved through program control. The Z-axis displacement adjustment module is located on the rear side of the fixed support module 1, and the microfluidic chip module 6, which is clamped and fixed by the chip clamping mechanism 3, is located inside the Z-axis displacement adjustment module. Under the drive of the Z-axis displacement adjustment module, the position of the microfluidic chip module 6 along the Z-axis is adjusted. The Y-axis displacement adjustment modules are symmetrically arranged on the left and right sides of the fixed support module 1 along the Y-axis. The X-axis displacement adjustment modules are located above the Y-axis displacement adjustment modules on both sides. Under the drive of the Y-axis displacement adjustment modules, the X-axis displacement adjustment modules are moved along the Y-axis. The piezoelectric drive module 2 is located above the X-axis displacement adjustment modules, driving the piezoelectric drive module 2 to move along the X-axis.

[0066] Furthermore, the X-axis displacement adjustment module adopts an X-axis linear motor fine-tuning platform 8; the Y-axis displacement adjustment module includes a Y-axis fine-tuning platform 10 and a Y-axis linear motor 11; the Y-axis linear motor 11 drives the Y-axis fine-tuning platform 10 to move along the Y-axis; the Z-axis displacement adjustment module includes a Z-axis fine-tuning platform 4 and a Z-axis linear motor 5; the Z-axis linear motor 5 drives the Z-axis fine-tuning platform 4 to move along the Z-axis; wherein, both the Y-axis fine-tuning platform 10 and the Z-axis fine-tuning platform 4 adopt a structure of precision lead screw module, guide rail and connecting fastener 12; through the connecting fastener 12, it is fixed to the fixed support module 1 to ensure stable position after power-on and no displacement deviation during operation; the precision lead screw module is linked with the linear motor, and the adjustment accuracy can reach 10 micrometers, realizing the precise alignment of the piezoelectric drive module 2 and the microfluidic chip module 6. The guide rail ensures the smoothness of platform movement, and the connecting fastener adopts a 3D printed custom structure to adapt to the assembly requirements of the motor and the frame, and the structural stability is improved by fixing with multi-directional screws.

[0067] (iv) Piezoelectric drive module 2

[0068] See Figures 2-6In one specific implementation, the piezoelectric drive module 2 includes a signal generator, a drive signal adapter module, a piezoelectric stack, and an actuator clamp 14. The piezoelectric stack is clamped and fixed by the actuator clamp 14. The drive waveform output by the signal generator is applied to the piezoelectric stack after passing through the drive signal adapter module. The piezoelectric stack, as the core actuator, has the advantages of both stroke and impact force, and is easily separated and installed from the microfluidic chip module 6. It is composed of multiple piezoelectric sheets stacked together, and converts electrical signals into precise mechanical displacement through the inverse piezoelectric effect, acting on the fluid to generate droplets. The signal generator uses a RIGOLD G852Pro generator, which supports multiple waveform outputs. It works in conjunction with the control module 13 to adjust voltage and frequency parameters. After experimental optimization, a rectangular wave was selected as the drive waveform. The input voltage is 6V and the frequency is 1Hz, which can effectively reduce the generation of satellite droplets and improve the stability of droplet generation.

[0069] Furthermore, the actuator clamp 14 adopts a symmetrical semi-circular clamping arm structure, consisting of two symmetrical semi-circular clamping arms, which disperses the clamping shear force on the piezoelectric stack and avoids damage to the surface of the piezoelectric stack. The actuator clamp 14 includes an actuator fixing base 14-1 and a pre-tightening adjustment clamping plate 14-2. The actuator fixing base 14-1 is fixed to the X-direction displacement adjustment module by bolts through standard mounting holes, and a first semi-circular groove is provided in the middle along the Y direction. The pre-tightening adjustment clamping plate 14-2 is fixed above the actuator fixing base 14-1 by pre-tightening adjustment bolts, and a second semi-circular groove symmetrical to the first semi-circular groove is provided. The first semi-circular groove and the second semi-circular groove enclose and form a clamping surface for accommodating and clamping the piezoelectric stack.

[0070] Therefore, the actuator clamp 14 has the advantages of precise positioning, compact structure and convenient operation, and the outward extension design provides space for droplet droplets to fall, which is suitable for experimental needs.

[0071] (v) Chip clamping mechanism 3

[0072] See Figure 7 As one specific implementation, the chip clamping mechanism 3 includes an elastic gripper 3-1, a profile base 3-2, a fixed end plate 3-3, a butterfly knob 3-4, a bidirectional adjusting screw 3-5, and an internal hexagon 3-6; the profile base 3-2 is rigidly connected to the Z-axis displacement adjustment module, and vibration interference is avoided through mechanical structure optimization, ensuring the relative positional accuracy of the microfluidic chip module 6 and the piezoelectric stack.

[0073] The fixed end plates 3-3 are symmetrically fixed on the left and right sides of the profile base 3-2; the bidirectional adjusting screw 3-5 passes through the left and right sides of the profile base 3-2, and each end of the screw is fixed with a butterfly knob 3-4; the bidirectional adjusting screw 3-5 is rotated by the butterfly knobs 3-4 on both sides; elastic grippers 3-1 are symmetrically installed on the left and right sides of the bidirectional adjusting screw 3-5, and the elastic grippers 3-1 on both sides move in opposite directions under the action of the bidirectional adjusting screw 3-5; a microfluidic chip module 6 is set between the elastic grippers 3-1 on both sides; wherein, each elastic gripper 3-1 has a groove on the side facing the microfluidic chip module 6 to ensure that the microfluidic chip module 6 is firmly clamped and does not cause squeezing damage; the gripper surface adopts an anti-slip design to improve experimental stability; each elastic gripper 3-1 is provided with an internal hexagon 3-6 for adjusting the size of the elastic gripper 3-1.

[0074] Therefore, by precisely adjusting the opening and closing degree and clamping force of the elastic gripper 3-1 through the bidirectional adjusting screw 3-5, it can adapt to different sizes of microfluidic chip modules 6, mainly with a length of about 64mm and a width of about 40mm. This can not only securely fix the microfluidic chip module 6, but also avoid damage caused by excessive clamping. In addition, the elastic gripper 3-1 is designed to facilitate chip installation and replacement.

[0075] (vi) Microfluidic chip module 6

[0076] See Figure 8 The microfluidic chip module 6 includes a microfluidic chip substrate. Inside the microfluidic chip substrate, there are T-shaped microchannels, including a vertical microchannel and a horizontal microchannel that intersects with the middle of the vertical microchannel. The upper and lower ends of the vertical microchannel are a continuous phase inlet 6-1 and an outlet 6-3, respectively. One end of the horizontal microchannel is a dispersed phase inlet 6-4, and the other end intersects with the vertical microchannel, which is called the flow path intersection point 6-2.

[0077] As a specific structure, the microfluidic chip module 6 is made of PDMS or glass, with a length of about 64mm, a width of about 40mm, and a thickness of about 7.2mm. The microchannel depth is 100μm, and the overall microchannel length is 58cm and the width is 26cm, providing a core channel for droplet generation. The inlet of the fluid delivery system is adapted to the inlet of the chip, and the dual-channel injection pump is connected to the microfluidic chip module 6 through a hose to ensure stable fluid delivery.

[0078] The microfluidic chip module 6 adopts a standardized design in appearance, size, and shape. Only the internal microchannel structure can be adjusted according to experimental needs. It can be quickly replaced in conjunction with the chip clamping mechanism 3, thereby improving experimental efficiency.

[0079] (vii) Fluid transport system

[0080] The fluid delivery system includes a dual-channel syringe pump, a corrosion-resistant hose, and a Luer connector. The dual-channel syringe pump is a high-precision fluid delivery device that uses a stepper motor to drive a ball screw mechanism to achieve precise delivery at the nanoliter to milliliter level with stable flow and no pulsation. The corrosion-resistant hose connects the syringe pump to the inlet of the microfluidic chip module 6 and is suitable for experimental fluids such as droplets of oil and aqueous solutions. The Luer connector ensures a tight seal to prevent fluid leakage and is standardized to fit the inlet of the microfluidic chip module 6 for easy and quick replacement. Therefore, the dual-channel syringe pump, which uses a mechanical device to push the syringe piston, achieves precise delivery at the nanoliter to milliliter level. It has the advantages of stable flow, low pulsation, and good repeatability. Compared with peristaltic pumps and diaphragm pumps, it is more suitable for the microfluidic droplet generation requirements and is responsible for injecting two immiscible liquids into the microfluidic chip module 6.

[0081] (viii) Control Module 13 and Observation Components

[0082] In this invention, under the control of the control module 13 and the observation component, the piezoelectric drive module 2 works in concert with the fluid delivery system. Under the command of the control module 13, the piezoelectric drive module 2 outputs precise mechanical displacement, which, in conjunction with the fluid delivery system, enables the output end of the microfluidic chip module 6 to generate the target droplet.

[0083] The control module 13 may include a touch screen and a computer port to control the displacement adjustment module to reach a designated position, and the observation component is photographed by an external high-speed camera to observe the state of droplet formation.

[0084] The control module 13 has a built-in program that can receive adjustment commands and calculate the three-dimensional displacements of X, Y, and Z. It can send precise control signals from a computer user terminal or a touch screen to the piezoelectric drive module 2 and the displacement adjustment module. The observation components include an external fluorescence microscope and camera, which are used to check the microchannel status, adjust the position of the microfluidic chip module 6, and record the droplet generation process, so as to facilitate real-time monitoring and optimization of experimental parameters.

[0085] In this invention, non-standard parts, such as fixture bases and connectors, are manufactured using 3D printing. SolidWorks 3D models are converted to STL format and imported into the printing system, then sliced ​​and printed, reducing processing costs and time. Standard parts, such as bolts, angle brackets, syringes, and hoses, are procured for easy assembly and maintenance.

[0086] In the piezoelectric-driven microfluidic droplet controllable generation method provided by the present invention, the droplet generation process is as follows: the driving voltage, frequency and flow parameters are set by the control module 13, the signal generator generates a corresponding rectangular wave signal, and the piezoelectric stack converts the electrical signal into mechanical displacement; the fluid delivery system accurately delivers two immiscible liquids to the two microchannels of the microfluidic chip module 6; under the pulse pressure of the piezoelectric stack, combined with the fluid shear force and interfacial tension, the liquid forms monodisperse droplets in the microchannels and finally drips onto the support stage 7. The entire process is observed and recorded in real time by a fluorescence microscope and a camera.

[0087] This invention provides a method for a piezoelectrically driven microfluidic droplet controllable generation device, comprising the following steps:

[0088] Step S1: Using the programmable control unit as the core, the host computer and control module 13 work together to set key process parameters such as the driving voltage, driving frequency, continuous phase fluid flow rate and dispersed phase fluid flow rate of the piezoelectric stack of the piezoelectric drive module.

[0089] Step S2: Under the action of the displacement adjustment module, adjust the Z-axis height of the microfluidic chip module 6 and adjust the X and Y-axis positions of the piezoelectric drive module 2 so that the signal output area of ​​the piezoelectric drive module 2 is aligned with the liquid outlet 6-3 area of ​​the microfluidic chip module 6.

[0090] Step S3: Start the signal generator and fluid delivery system of the piezoelectric drive module;

[0091] The fluid delivery system independently controls the flow rates of the continuous phase fluid and the dispersed phase fluid, delivering the two immiscible fluids to the microchannels of the microfluidic chip module 6 at a set constant flow rate. The flow rate of the dispersed phase fluid is controlled at 0.1–5 μL / min, and the flow rate of the continuous phase fluid is controlled at 1–20 μL / min. The flow rate ratio of the two phase fluids is maintained in the range of 1:5 to 1:10 to ensure that the droplet necking and breakup process is stable and controllable.

[0092] The signal generator receives control commands from the host computer and the control module 13, and outputs a rectangular wave drive signal with a specified drive voltage amplitude, drive frequency and duty cycle as pulse excitation. This parameterized control method can realize high-precision adjustment of the drive signal, laying the foundation for dynamic control of the droplet generation process.

[0093] As a preferred approach, the driving voltage amplitude is set to 0–100V, the driving frequency is adjustable in the range of 1Hz–5kHz, and the duty cycle is set to 30%–70%, thereby obtaining stable pulse excitation.

[0094] After receiving the rectangular wave drive signal, the piezoelectric stack efficiently converts electrical energy into periodic mechanical displacement based on the inverse piezoelectric effect. This generates high-frequency, low-amplitude mechanical vibrations in the local area of ​​the microchannel in the microfluidic chip module 6, which are further converted into a pulsed pressure field acting on the fluid. This enables active control of the fluid interface and provides a key power source for precise droplet drop. Compared with the traditional constant pressure drive method, this pulsed pressure has the characteristics of strong controllability, fast response speed, and high disturbance accuracy, enabling active control of the fluid interface and providing a key power source for precise droplet drop.

[0095] The two-phase fluid undergoes shear focusing and droplet generation, shearing and necking fracture to form independent droplets, which finally drip from the outlet 6-3 of the microfluidic chip module 6.

[0096] The droplet generation process is as follows:

[0097] A1, Introduction of two-phase fluid:

[0098] Continuous phase (oil phase) fluid: Injected from the continuous phase inlet 6-1, flows vertically downwards along the microchannel, and flows perpendicularly towards the flow path intersection point 6-2;

[0099] Dispersed phase (aqueous phase) fluid: Injected horizontally into the dispersed phase inlet 6-4 of the microchannel, and flows horizontally towards the flow path intersection point 6-2;

[0100] A2, Shear Focusing and Liquid Filament Generation:

[0101] At the flow path intersection point 6-2, the two-phase fluids interact and generate a liquid filament through shear focusing; specifically, the horizontally flowing dispersed phase fluid is squeezed and constrained by the vertically flowing continuous phase fluid to form an extremely fine liquid filament, a process called fluid shear focusing.

[0102] By pre-focusing the dispersed phase fluid with the continuous phase fluid, a stable two-phase interface and initial fluid morphology are formed, providing a stable flow field basis for the subsequent droplet shearing process. The flow stability at this stage directly affects the uniformity of droplet generation.

[0103] A3, shearing and necking fracture, generating microdroplets:

[0104] As the flow path converges at point 6-2, the continuous phase fluid continues to flow toward the bottom outlet 6-3. The viscous shear force (horizontal component + vertical component) of the continuous phase fluid acts on the liquid filament, causing the liquid filament to neck. When the viscous shear force exceeds the balance between the interfacial tension and viscous resistance of the dispersed phase fluid, the liquid filament will be broken, forming independent microdroplets.

[0105] A4, the generated microdroplets are entrained by the continuous phase fluid and continue to flow vertically downwards along the microchannel. Simultaneously, the piezoelectric drive module vibrates the microfluidic chip 6, generating regular vibrations. Hydrophobic treatment is applied at the outlet 6-3, ultimately resulting in monodisperse microdroplets with a diameter of 50–300 μm flowing out from the bottom outlet 6-3. For example... Figure 10 The image shown is an image of the generated microdroplets under a microscope.

[0106] Therefore, closed-loop feedback control of the injection pump ensures flow accuracy. The generated microdroplets flow along the microchannel with the continuous phase fluid. Simultaneously, piezoelectric ceramic vibrations act on the microfluidic chip to generate regular vibrations. Furthermore, the outlet extension (outlet 6-3) is treated with hydrophobicity to address issues such as tailing, adhesion, coalescence, and interfacial instability at the outlet after droplet formation, ensuring stable outflow of monodisperse droplets without affecting the flow field in the upstream shear zone. Finally, the droplets flow from the chip outlet and drip into a storage container on the container placement platform, completing droplet collection and storage. The entire droplet formation process is observed and recorded in real time using a fluorescence microscope and a high-speed imaging system, dynamically capturing the entire process of droplet nucleation, shearing, breakage, and flow. This provides intuitive experimental evidence for analyzing the droplet formation mechanism, size distribution, and stability under different process parameters.

[0107] As an example:

[0108] During implementation, the piezoelectric-driven microfluidic droplet controllable generator provided in this embodiment is placed on a horizontal experimental platform. First, the device is started through the computer user terminal to check whether the displacement adjustment module, including the X-axis displacement adjustment module, Y-axis displacement adjustment module and Z-axis displacement adjustment module, as well as the piezoelectric drive module 2 and the fluid delivery system are operating normally.

[0109] The chip clamping mechanism 3 is pushed out by the displacement adjustment module, and the microfluidic chip module 6 with a channel depth of 100μm and a total channel length of 58cm is placed into the elastic gripper 3-1. The bidirectional adjustment screw 3-5 is adjusted to complete the fixation.

[0110] Subsequently, the user terminal issues a command to reset the platform; the liquid droplets are loaded with oil and colored paste aqueous solution respectively through a dual-channel syringe pump, and connected to the inlet of the microfluidic chip module 6 through a hose to ensure no blockage or leakage; the driving parameters of rectangular wave, 6V voltage, 1Hz frequency and syringe pump flow rate are set through the control module 13, the piezoelectric stack is connected to the signal generator, the piezoelectric drive module 2 and the fluid delivery system are started, the signal generator emits a rectangular wave, and the piezoelectric stack generates mechanical vibration that acts on the fluid in the microfluidic chip module 6. The user terminal issues commands to the X / Y / Z axes to reach different positions to receive the droplets, forming monodisperse droplets that fall vertically into the container on the support stage 7. The droplet generation status can be monitored in real time through a microscope and a high-speed camera.

[0111] After the experiment is completed, the platform is reset via the user terminal, the injection pump and piezoelectric drive module 2 are turned off, the chip clamping mechanism 3 is pushed out via the X / Y / Z displacement adjustment module, the microfluidic chip module 6 is taken out, the channel is rinsed with methanol solution and water in sequence and then stored properly; if the experimental scheme needs to be changed, only the standardized chip with the corresponding internal microchannel needs to be replaced and the above operation is repeated.

[0112] As can be seen, the piezoelectric-driven microfluidic droplet controllable generator provided in this embodiment achieves stability and controllability of droplet generation through piezoelectric drive and intelligent user-end precision control platform technology. When the flow rate is stable, the uniformity of droplet size is significantly improved and droplet waste is reduced. The standardized microfluidic chip module 6 design and quick-change structure greatly shorten the experimental preparation time. The device is controlled by both a user-end visualization window and a touch screen, making the system more stable, highly intelligent, and with good droplet generation accuracy. The device has a compact structure, is easy to operate, and has good reagent compatibility. It can be widely used in microfluidic experiments in fields such as microfluidic inkjet printing. It also has advantages such as low reagent consumption and environmental friendliness, balancing scientific research efficiency and economy.

[0113] The present invention provides a piezoelectrically driven microfluidic droplet controllable generation device and method, which has the following advantages:

[0114] This invention achieves on-demand droplet generation by precisely controlling pulse signals, and combined with automated control logic, significantly improves the stability of droplet generation and experimental efficiency. The microfluidic chip module adopts a standardized appearance design with uniform size, shape and interface specifications. It adapts to different experimental needs only through differentiated internal microchannels, enabling rapid chip replacement, reducing operational complexity and further optimizing the experimental process.

[0115] This invention uses piezoelectric drive technology as its core, combining the high precision of active control with the fast response of mechanical drive. With the addition of rectangular wave optimized parameters, the droplet generation exhibits strong stability and high controllability. Furthermore, the piezoelectric drive is reagent and material friendly, making it suitable for experiments in precision fields such as inkjet printing in printed electronics, which is one of the innovative aspects of this invention.

[0116] This invention achieves precise positioning and stable fixation of the microfluidic chip module and the piezoelectric drive module through the collaborative design of an X / Y / Z fine-tuning platform, a symmetrical clamping arm actuator fixture, and a bidirectional screw chip clamping mechanism. Furthermore, the standardized design and convenient clamping structure of the microfluidic chip module facilitates rapid replacement, significantly improving experimental efficiency, which is one of the innovative aspects of this invention.

[0117] This invention uses an aluminum alloy base and 3D-printed non-standard parts, resulting in a compact structure and light weight. It is combined with a dual-channel syringe pump to replace the traditional high-precision syringe pump, which reduces equipment costs and eliminates dependence on fixed laboratory instruments. It also has good adaptability to experimental environments, which is one of the innovations of this invention.

[0118] This invention integrates microfluidic chips, piezoelectric drive, precise displacement adjustment, and direct user-end control functions. It features a high degree of process automation and intelligence, simple operation, and precise control of droplet volume through parameter adjustment. It also consumes less reagent, aligns with the trend of green technology development, and has both scientific value and social benefits, which is one of the innovative points of this invention.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A microfluidic droplet controllable generation device based on piezoelectric actuation, characterized in that, include: Fixed support module (1), piezoelectric drive module (2), chip clamping mechanism (3), microfluidic chip module (6), carrier platform (7), fluid delivery system, control module (13) and displacement adjustment module; The fixed support module (1) is equipped with the displacement adjustment module; the displacement adjustment module is used to adjust the position of the piezoelectric drive module (2) in the XY plane and the position of the microfluidic chip module (6) held by the chip clamping mechanism (3) along the Z direction, so that the signal output area of ​​the piezoelectric drive module (2) is aligned with the fluid output port of the microfluidic chip module (6); The fluid delivery system is connected to two fluid input ports of the microfluidic chip module (6) respectively, and is used to deliver two immiscible liquids to the microfluidic chip module (6). The two liquids are mixed through the microchannel of the microfluidic chip module (6). Under the pulse pressure of the piezoelectric drive module (2), combined with fluid shear force and interfacial tension, the mixed liquid forms monodisperse droplets in the microchannel. The support platform (7) is located below the microfluidic chip module (6) and is used to receive the monodisperse droplets dripping from the fluid output port of the microfluidic chip module (6). The control module (13) is connected to the piezoelectric drive module (2) and the displacement adjustment module, and is used to control the piezoelectric drive module (2) and the displacement adjustment module.

2. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 1, characterized in that, The displacement adjustment module includes an X-axis displacement adjustment module, a Y-axis displacement adjustment module, and a Z-axis displacement adjustment module; The Z-direction displacement adjustment module is located on the rear side of the fixed support module (1), and the microfluidic chip module (6) is clamped and fixed by the chip clamping mechanism (3) on the inner side of the Z-direction displacement adjustment module. Under the drive of the Z-direction displacement adjustment module, the position of the microfluidic chip module (6) along the Z direction is adjusted. The Y-direction displacement adjustment module is symmetrically arranged on the left and right sides of the fixed support module (1) along the Y direction. The X-direction displacement adjustment module is arranged on the top of the Y-direction displacement adjustment modules on both sides along the X direction. Under the drive of the Y-direction displacement adjustment module, the X-direction displacement adjustment module is moved along the Y direction. The piezoelectric drive module (2) is arranged on the top of the X-direction displacement adjustment module, and the piezoelectric drive module (2) is moved along the X direction.

3. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 2, characterized in that, The X-axis displacement adjustment module adopts an X-axis linear motor fine-tuning platform (8); the Y-axis displacement adjustment module includes a Y-axis fine-tuning platform (10) and a Y-axis linear motor (11); the Y-axis linear motor (11) drives the Y-axis fine-tuning platform (10) to move along the Y direction; the Z-axis displacement adjustment module includes a Z-axis fine-tuning platform (4) and a Z-axis linear motor (5); the Z-axis linear motor (5) drives the Z-axis fine-tuning platform (4) to move along the Z direction; wherein, the Y-axis fine-tuning platform (10) and the Z-axis fine-tuning platform (4) both adopt a structure of precision lead screw module, guide rail and connecting fastener (12); and are fixed to the fixed support module (1) through the connecting fastener (12).

4. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 2, characterized in that, The piezoelectric drive module (2) includes a signal generator, a drive signal adapter module, a piezoelectric stack, and an actuator clamp (14); the piezoelectric stack is clamped and fixed by the actuator clamp (14); the drive waveform output by the signal generator is applied to the piezoelectric stack after passing through the drive signal adapter module; the piezoelectric stack is composed of multiple piezoelectric sheets stacked together, and converts the electrical signal into precise mechanical displacement through the inverse piezoelectric effect, which is applied to the fluid to generate droplets.

5. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 4, characterized in that, The actuator clamp (14) adopts a symmetrical semi-circular clamp arm structure to disperse the clamping shear force on the piezoelectric stack and avoid damage to the surface of the piezoelectric stack; the actuator clamp (14) includes an actuator fixing base (14-1) and a pre-tightening adjustment clamp (14-2). The actuator mounting base (14-1) is fixed to the X-direction displacement adjustment module through a standard mounting hole, and a first semi-circular groove is provided in the middle along the Y direction; The pre-tightening adjustment clamp (14-2) is fixed above the actuator fixing base (14-1) by pre-tightening adjustment bolts, and a second semi-circular groove symmetrical to the first semi-circular groove is provided. The first semi-circular groove and the second semi-circular groove together form a clamping surface for accommodating and holding the piezoelectric stack.

6. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 1, characterized in that, The chip clamping mechanism (3) includes an elastic gripper (3-1), a profile base (3-2), a fixed end plate (3-3), a butterfly knob (3-4), a bidirectional adjusting screw (3-5), and an internal hexagonal screw (3-6). The fixed end plates (3-3) are symmetrically fixed on the left and right sides of the profile base (3-2); the bidirectional adjusting screw (3-5) passes through the left and right sides of the profile base (3-2), and the butterfly knobs (3-4) are fixed at both ends; the bidirectional adjusting screw (3-5) is controlled to rotate by the butterfly knobs (3-4) on both sides; the elastic claws (3-1) are symmetrically installed on the left and right sides of the bidirectional adjusting screw (3-5), and under the action of the bidirectional adjusting screw (3-5), the two... The elastic grippers (3-1) on both sides move in opposite directions; the microfluidic chip module (6) is disposed between the elastic grippers (3-1) on both sides; wherein, each elastic gripper (3-1) on one side has a groove on the side facing the microfluidic chip module (6) to ensure that the microfluidic chip module (6) is clamped firmly and without causing squeezing damage; each elastic gripper (3-1) on one side is provided with an internal hexagon (3-6) for adjusting the size of the elastic gripper (3-1).

7. The microfluidic droplet controllable generation device based on piezoelectric drive according to claim 1, characterized in that, The microfluidic chip module (6) includes a microfluidic chip substrate. Inside the microfluidic chip substrate, there are microchannels arranged in a T-shape, including a vertical microchannel and a horizontal microchannel that intersects with the middle of the vertical microchannel. The upper and lower ends of the vertical microchannel are a continuous phase inlet (6-1) and an outlet (6-3), respectively. One end of the horizontal microchannel is a dispersed phase inlet (6-4), and the other end intersects with the vertical microchannel, which is called the flow path intersection point (6-2).

8. A method for a piezoelectrically driven microfluidic droplet controllable generation device according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: With the programmable control unit as the core, the drive voltage, drive frequency, continuous phase fluid flow rate and dispersed phase fluid flow rate of the piezoelectric stack of the piezoelectric drive module are set in collaboration between the host computer and the control module (13). Step S2: Under the action of the displacement adjustment module, adjust the Z-axis height of the microfluidic chip module (6) and adjust the X-axis and Y-axis positions of the piezoelectric drive module (2) so that the signal output area of ​​the piezoelectric drive module (2) is aligned with the liquid outlet (6-3) area of ​​the microfluidic chip module (6); Step S3: Start the signal generator and fluid delivery system of the piezoelectric drive module; The fluid delivery system independently controls the flow rates of the continuous phase fluid and the dispersed phase fluid, delivering the two immiscible fluids to the microchannel of the microfluidic chip module (6) at a set constant flow rate. The flow rate of the dispersed phase fluid is controlled at 0.1–5 μL / min, the flow rate of the continuous phase fluid is controlled at 1–20 μL / min, and the flow rate ratio of the two phase fluids is maintained in the range of 1:5 to 1:

10. The signal generator outputs a rectangular wave drive signal with a specified drive voltage amplitude, drive frequency, and duty cycle as pulse excitation; wherein, the drive voltage amplitude is set to 0–100V, the drive frequency is adjustable in the range of 1Hz–5kHz, and the duty cycle is set to 30%–70%; After receiving the rectangular wave drive signal, the piezoelectric stack efficiently converts electrical energy into periodic mechanical displacement based on the inverse piezoelectric effect. This generates high-frequency, low-amplitude mechanical vibrations in the local area of ​​the microfluidic chip module (6), which are further converted into pulsed pressure fields acting on the fluid. This enables active control of the fluid interface and provides a key power source for the precise droplet drop. The two-phase fluids undergo shear focusing and droplet generation, shearing and necking fracture to form independent droplets, which finally drip from the outlet (6-3) of the microfluidic chip module (6).

9. The method for a piezoelectrically driven microfluidic droplet controllable generation device according to claim 8, characterized in that, The droplet generation process is as follows: A1, Introduction of two-phase fluid: Continuous phase fluid: Injected from the continuous phase inlet (6-1), flows vertically downward along the microchannel, and flows perpendicularly to the flow path intersection point (6-2). Dispersed phase fluid: Injected horizontally into the dispersed phase inlet (6-4) of the microchannel, flowing horizontally towards the flow path junction (6-2). A2, Shear Focusing and Liquid Filament Generation: At the flow path intersection (6-2), the two-phase fluids interact and generate a liquid filament through shear focusing; specifically, the horizontally flowing dispersed phase fluid is squeezed and constrained by the vertically flowing continuous phase fluid to form an extremely fine liquid filament, a process called fluid shear focusing. A3, shearing and necking fracture, generating microdroplets: As the flow path converges at (6-2), the continuous phase fluid continues to flow toward the bottom outlet (6-3). The viscous shear force of the continuous phase fluid acts on the liquid filament, causing the liquid filament to neck. When the viscous shear force exceeds the balance between the interfacial tension and viscous resistance of the dispersed phase fluid, the liquid filament will be broken, forming independent microdroplets. A4, the generated microdroplets are carried by the continuous phase fluid and continue to flow vertically downwards along the microchannel. At the same time, the microfluidic chip module (6) is vibrated regularly by the vibration of the piezoelectric drive module. The outlet (6-3) is hydrophobically treated and finally the monodisperse microdroplets flow out from the outlet (6-3) at the bottom.

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