CN1232728C - Valve less thin film driving micro pump - Google Patents

Abstract

The present invention discloses a valve less thin film driving micro pump. The micro pump is in a structure with a single film and double cavities. The double cavities are completely isolated by a driving film composed of a basement membrane and a function film. Each pump cavity is connected with a water inlet hole via a corresponding conical diffusion tube and is connected with a water outlet hole via a corresponding conical converging tube. The present invention adopts the structure with the single film and double cavities and utilizes signals to control the variation of the volume of the two cavities, which causes the variation of the volume of the two cavities to obtain complementation at real time and causes the output flow to be stable. The present invention has the characteristics of simple structure, simple preparing process, quick response, wide driving frequency, high controllability, low energy consumption, long service life, etc. In addition, the valve less thin film driving micro pump can adopt the material and technology for manufacturing in which fine processing is compatible with micro mechanical technology, has the characteristics of small volume, low cost, easy integration with other micro detection elements and micro control elements, etc., is suitable for mass production, and has a remarkable application prospect.

Description

Valveless membrane driven micropump

technical field

The invention relates to a film-driven micropump, which belongs to microfluidic transmission and control, micromechanical

technology field.

Background technique

The microfluidic control system can accurately detect and control the flow rate of microliters per minute, and has important application prospects in micro-delivery of drugs, micro-injection of fuel, cell separation, cooling of integrated electronic components, and microchemical analysis. As an important microfluidic actuator, the micropump is an important symbol of the development level of the microfluidic system. At present, the membrane-driven micropump is widely used, and its flow control is realized by changing the volume of the pump cavity caused by the reciprocating motion of the driving membrane. The driving principles of the driving membrane include piezoelectric, electrostatic, electromagnetic, thermopneumatic, bimetallic effect and shape memory effect driving. Among all kinds of drivers using the above driving methods, piezoelectric drivers have attracted much attention due to their fast response, high bearing capacity, low energy consumption and low price. Membrane-driven micropumps can be divided into valved micropumps and valveless micropumps according to whether they have a movable valve or not. Valved micropumps are often based on mechanical drive, with simple principles, mature manufacturing processes, and easy control, and are the mainstream of current applications; valveless micropumps use the new characteristics of fluids in micro-scale, novel principles, and are more suitable for miniaturization. Greater prospects for development. Regardless of whether there is a movable valve or not, the membrane-driven micropumps currently used generally adopt a single-membrane single-chamber structure, and the volume change of the single chamber is controlled by a periodic signal. It is assumed that the volume of the cavity increases in the first half cycle, and the micropump is in the suction state; otherwise, the volume of the pump cavity decreases in the second half cycle, and the micropump is in the pumping state. In a working cycle, the microfluidic output only exists in the second half cycle, and the pumping and suction cannot be performed at the same time. Therefore, there are periodic fluctuations and flow instability, which greatly limits the popularization and application of membrane-driven micropumps.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a valveless film-driven micropump, which is a single-membrane double-chamber structure, which can effectively solve the problems of periodic fluctuations and flow instability , so that the output flow is continuous and stable.

In order to achieve the above object, the technical solution adopted by the present invention is: the upper pump body is provided with an upper pump chamber, a tapered diffuser pipe, a tapered shrink pipe, a left water hole and a right water hole, and the upper pump chamber passes through the diffuser pipe. It is connected to the water hole on the left side, and connected to the water hole on the right side through the shrink tube. There is a lower pump body under the upper pump body, and the corresponding lower pump chamber, tapered diffuser tube, tapered shrink tube and Corresponding to the left water hole and the right water hole, the lower pump chamber is connected to the left water hole through the diffusion tube, and connected to the right water hole through the shrinkage tube. The upper and lower pump chambers are driven membranes composed of basement membrane and functional membrane. In isolation, the taper angles of the two diffusers and the two constrictors are equal.

The advantages of the present invention are:

1. Since the present invention adopts a single-membrane double-cavity structure, the volume changes of the two cavities are controlled by signals, so that the volume changes of the two cavities are complemented in real time, the output flow is continuous and stable, and it has simple structure and process, fast response, Wide drive frequency, strong controllability, low energy consumption, long life and so on.

2. The present invention can be manufactured using materials and processes compatible with micromachining and micromechanical technology, and has the characteristics of small size, low cost, easy integration with other micro-detection and micro-control components, etc., and is suitable for mass production.

Description of drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention.

Fig. 2 is a sectional view of A-A in Fig. 1 .

FIG. 3 is an axial view of the embodiment of FIG. 1 .

Fig. 4 is a schematic structural diagram of another embodiment of the present invention.

FIG. 5 is a schematic structural diagram of the driving membrane in FIG. 4 .

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 3, an upper pump chamber 4, a conical diffuser tube 3, a conical shrink tube 7, a left water hole 2 and a right water hole 8 are opened on the upper pump body 1. A layer of functional film 6 is placed on the surface of the base film 5 of the upper pump body 1 to form a driving film. The functional film can be a piezoelectric film or a magnetoelectric film. The upper pump chamber 4 is connected with the water hole 2 through the diffuser tube 3 and connected with the water hole 8 through the shrink tube 7 . There is a lower pump body 13 below the upper pump body 1, and a corresponding lower pump chamber 11, a tapered diffuser tube 12, a tapered shrink tube 10, and corresponding water holes 2 and water holes 8 are opened on the lower pump body 13. The pump chamber 11 is connected with the water hole 2 through the diffuser tube 12 and connected with the water hole 8 through the shrink tube 10 . The upper and lower pump chambers 4, 11 are separated by the above-mentioned driving membrane. The taper angles of the two diffuser tubes 3, 12 and the two shrink tubes 7, 10 are equal. A cover 9 is arranged on the top of the upper pump body 1, on which corresponding left water holes 2 and right water holes 8 are formed.

When the taper angle a of the conical diffuser tubes 3 and 12 and the conical contraction tubes 7 and 12 is between 5° and 12°, the output capacity of the pump is relatively large.

When working, the driving membrane will undergo a nearly parabolic deformation under the excitation of the alternating electric signal, so that the volume of the pump chamber will alternately change in increase and decrease. Now take the water hole 2 as the water inlet and the water hole 8 as the water end. When the volume of the upper pump chamber 4 is reduced by ΔV, the output flow rate of the expansion tube 3 of the upper pump cavity is Q ₁ , and the output flow rate of the contraction tube 7 is Q ₂ . The tube and shrink tube are tapered in the direction of fluid flow. According to the flow characteristics of the fluid in the shrink tube and expand tube, Q ₂ >Q ₁ , that is, the upper pump chamber 4 is in the pumping state; at the same time, the volume of the lower pump chamber 11 increases accordingly ΔV, set the input flow rate of the expansion tube 12 _of the lower pump _chamber as Q ₃ , and the input flow rate of the contraction tube 10 as Q ₄ . state. At the end of the water inlet hole 2, the expansion tube 3 of the upper pump chamber actually acts as a fluid contraction, and the expansion tube 12 of the lower pump chamber acts as a fluid expansion effect, Q ₃ >Q ₁ , the whole pump is in the suction state at the end of the water inlet hole 2. At the outlet hole 8, the upper pump cavity constriction tube 7 actually acts as a fluid expansion, and the lower pump cavity constriction tube 10 acts as a fluid contraction, Q ₂ >Q ₄ , the whole pump is in the pumping state at the water outlet 8 end. Due to the corresponding arrangement of the upper and lower pump chambers 4 and 11, when the volume of the upper pump chamber 4 increases, it can be known from the above analysis process that the whole pump is still in the suction state at the end of the water inlet hole 2, and is in the pumping state at the end of the water outlet hole 8 . Therefore, in one working cycle, the micropump realizes continuous suction and pumping of fluid. The flow rate of the micropump is controlled by the amplitude and frequency of the alternating electric signal. At the same time, the invention uses a photosensitive polyimide film with stable chemical performance and good insulation performance as the electrical isolation layer, which improves the reliability and lifespan of the micropump.

The main technical indicators of the present invention can be achieved: the overall size is 8mm×8mm×1.5mm (length×width×height), the cavity size is 5mm×0.3mm (diameter×height), and the piezoelectric film size is 3mm×3mm×40μm ; The flow rate is continuously adjustable from 0.5-100μL/min; the maximum pump pressure is 2.6Kpa.

The specific technical process of the present invention is described in conjunction with Fig. 1. The micropump can be composed of three layers of silicon (glass) structures through a silicon (glass)-silicon (glass) bonding process, which are respectively an upper pump body, a lower pump body and a cover. First, a thick film preparation process is used to directly deposit a piezoelectric film of about 40 μm on the lower surface of the Si base of the upper pump body, and the deep reactive ion etching technology is used to etch the upper pump cavity and the water inlet hole on the back of the piezoelectric film. , Outlet hole, shrinkage tube, expansion tube. When etching the upper pump cavity, etch until the thickness of the Si film is about 100 μm. The manufacturing process of the lower pump body is the same as that of the upper pump body except for the preparation of the non-piezoelectric film. The production of the cover is relatively simple, only need to etch the corresponding water inlet and outlet holes. The three-layer structure is bonded together by silicon (glass)-silicon (glass) direct bonding process to form the whole pump. The whole processing process is very simple and suitable for mass production.

The structure of the present invention can also be shown in Fig. 4, Fig. 5, be made up of upper pump body 16, lower pump body 13 and driving membrane, and driving membrane is made of base film 15 and functional membrane 14, is fixed on upper pump body 16 and lower Between the pump body 13.

Obviously, the present invention is not only applicable to piezoelectric micropumps, but also can be applied to other film-driven micropumps, such as SMA film-driven micropumps, magnetic film-driven micropumps, bimetal heat-driven micropumps, hot gas-driven micropumps, etc.

Claims (3)

1. A valveless film-driven micropump, characterized in that: an upper pump chamber (4), a tapered diffuser tube (3), a tapered shrink tube (7), and a left pump body (1) are provided. The side water hole (2) and the right water hole (8), the upper pump chamber (4) is connected to the left water hole (2) through the diffuser tube (3), and the right water hole (8) through the shrink tube (7) ), there is a lower pump body (13) under the upper pump body (1), and a corresponding lower pump chamber (11), tapered diffuser tube (12), and tapered shrink tube are opened on the lower pump body (13). (10) and the corresponding left water hole (2), right water hole (8), the lower pump chamber (11) is connected to the left water hole (2) through the diffusion tube (12), and the shrink tube (10) Connected with the water hole (8) on the right side, the upper and lower pump chambers (4), (11) are separated by the driving membrane composed of the basement membrane (5) and the functional membrane (6), and the two diffusion tubes (3), (12 ) and the taper angles of the two shrink tubes (7), (10) are equal. 2. The valveless film-driven micropump according to claim 1, characterized in that: a cover (9) is placed on the upper pump body (1), and a corresponding left water hole (2) is opened on it. ) and the right water hole (8). 3. The valveless film-driven micropump according to claim 1 or 2, characterized in that: tapered diffuser tubes (3), (12), the taper angles of tapered shrink tubes (7), (10) a is 5° to 12°.

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