CN105201796A - Piezoelectric peristaltic micropump - Google Patents

Abstract

A piezoelectric peristaltic micropump, comprising a substrate and a piezoelectric actuator, the substrate is provided with a fluid channel, the number of the fluid channels is two, one fluid channel is used as the starting point of the delivery path, and the other fluid channel is used as the end point of the delivery path; The electric actuator is mainly composed of a piezoelectric layer, an upper electrode, a lower electrode and an elastic layer. The lower electrode completely covers the piezoelectric layer. The upper electrode, piezoelectric layer, lower electrode and elastic layer are arranged from top to bottom in sequence. The frame part and the base body are sealed and fixed, the area inside the outer frame part of the elastic layer is the pump cavity part, and the upper electrode, the lower electrode and the piezoelectric layer are located in the pump cavity part area; the upper electrode is composed of a plurality of separated electrode modules, separated The electrode modules are arranged equidistantly along the conveying path. The invention has the advantages of simple structure and bidirectional fluid flow.

Description

A piezoelectric peristaltic micropump

technical field

The invention belongs to the field of micro-electro-mechanical systems, and relates to micro-fluid transmission and control technology, in particular to a micro-peristaltic pump which uses a piezoelectric sheet to drive liquid flow.

technical background

In recent years, MEMS (Micro-Electro-MechanicalSystem) is a micro-device or system that inherits micro-mechanisms, micro-sensors, micro-actuators, signal processing and control circuits, and even interfaces, communications and power supplies. Based on material science, research, design, and manufacture of micro-devices with specific functions. Using micromachining technology to make microfluidic devices, which are used to transport, detect and control microliter flow and fluid devices, it is the basis of microfluidic systems, among which microvalves, micropumps, microchannels and microflow sensors are the most Representative microfluidic devices.

As the fluid-driven part of the micro-flow system, the micropump has important and extensive applications in micro-delivery of drugs, micro-injection of fuel, cell separation, cooling of integrated electronic components, genetic engineering, and microchemical analysis due to its ability to precisely drive and control fluids. Applications.

Chinese patent CN200610111204.8 discloses a self-priming micropump, which consists of three parts: the lower part of the pump body, the upper part of the pump body and the driver, wherein: there is an upper part of the pump body between the driver and the lower part of the pump body; There are pump cavity, valve seat, first tapered diffuser tube, tapered shrink tube, and second tapered diffuser tube on the lower body; between the first tapered diffuser tube and the second tapered diffuser tube on the lower body of the pump There is a valve seat between them, and a tapered shrink tube is inlaid on the valve seat. When this self-priming micropump works, first add a square wave AC signal to the piezoelectric driver, the piezoelectric driver vibrates periodically, the driver makes the pump membrane vibrate, and the constriction port of the conical shrink tube will be blocked and opened periodically , the diffusion port of the tapered diffuser tube is always open, the constricted port of the tapered shrink tube is used as the sample inlet, and the diffuser port of the tapered diffuser tube is used as the sample outlet. Due to the periodic vibration of the pump membrane under the periodic driving force, the volume of the pump cavity changes periodically, thereby realizing the suction and discharge of the working substance. The shortcoming of this self-priming micro-pump is: 1, the lower part of the pump body needs to be provided with a tapered diffuser tube and a tapered shrinkage tube, and the structure and manufacturing process of the lower part of the pump body are complicated. 2. The fluid can only flow from the conical shrinkage tube to the conical diffuser tube, and the two-way flow of the fluid cannot be realized. 3. The conical shrinkage tube and the conical diffuser tube are connected through the pump chamber. When the distance between the inlet and the sample outlet is large, the area covered by the pump chamber must be larger than the area between the inlet and the sample outlet. If the distance is large, the fluid in the pump chamber area away from the inlet is likely to adhere or stay in the pump chamber, resulting in loss of liquid volume.

Contents of the invention

In order to overcome the disadvantages of the prior art that conical pipes need to be provided, the structure and manufacturing process are complicated, and the fluid cannot flow in both directions, the present invention provides a piezoelectric peristaltic micropump with a simple structure and in which the fluid can flow in both directions.

A piezoelectric peristaltic micropump, including a base body and a piezoelectric actuator, and a fluid channel is opened on the base body. end point;

The piezoelectric actuator is mainly composed of piezoelectric layer, upper electrode, lower electrode and elastic layer. The lower electrode completely covers the piezoelectric layer. The upper electrode, piezoelectric layer, lower electrode and elastic layer are arranged from top to bottom in sequence. The elastic layer The outer frame part is sealed and fixed with the base body, and the area inside the outer frame part of the elastic layer is the pump chamber part; the upper electrode is composed of a plurality of separated electrode modules, and the separated electrode modules are arranged equidistantly along the conveying path. The first separated electrode module and The last separated electrode module corresponds to a fluid channel respectively; when the separated electrode module is powered on, a cavity is formed between the powered separated electrode module and the substrate; when the separated electrode module is de-energized, the de-energized separated electrode module is attached to the substrate The cavities formed by the front and back adjacent separation electrode modules are overlapping, and the separation electrode modules are energized sequentially from the starting point to the end point of the conveying path.

The first separate electrode module and the last separate electrode module correspond to a fluid channel respectively, which means that one fluid channel is under the first separate electrode module, and the other fluid channel is under the last separate electrode module. The cavities formed by adjacent separated electrode modules are overlapped from end to end, so that the fluid can be transferred from the cavity of one separated electrode module to the cavity of the next separated electrode module, so as to realize the delivery of fluid from the starting point to the ending point.

The upper electrode and the lower electrode are respectively attached to the piezoelectric layer, and the upper electrode and the lower electrode are directly attached to the piezoelectric layer without adhesive. The upper electrode, the lower electrode and the piezoelectric layer are located in the region of the pump chamber. A current loop is formed between the electrified separated electrode module in the upper electrode and the lower electrode, the piezoelectric layer area covered by the separated electrode module receives voltage, and the piezoelectric layer area covered by the separated electrode module deforms. The lower electrode is bonded and fixed to the elastic layer, so the deformation of the piezoelectric layer drives the deformation of the elastic layer, the elastic layer is far away from the substrate, and a cavity for containing fluid is formed between the elastic layer and the substrate.

The shape and size of the lower electrode and the piezoelectric layer are equal, and the lower electrode is a monolithic electrode. Each separated electrode module of the upper electrode is in the area of the piezoelectric layer, and the area of the elastic layer is larger than that of the lower electrode.

The upper surface of the base body in contact with the elastic layer is a plane, and the frame of the base body and the outer frame of the elastic layer are bonded with epoxy glue or sealed and fixed by means of MEMS bonding technology or the like. The part of the elastic layer that is not fixed to the base can be attached to the upper surface of the base. The elastic layer and the unfixed part of the base form a pump cavity.

The piezoelectric layer area covered by the separated electrode module that is not electrified or in a de-energized state maintains a natural state, and the elastic layer under the piezoelectric layer area that maintains a natural state remains bonded to the substrate.

The outer frame of the elastic layer is sealed and connected to the base, so when the first separated electrode module and the last separated electrode module are energized to form a cavity, the outer frame of the elastic layer is sealed with the base to prevent fluid from leaking out.

The starting point and end point of the delivery path are determined by the flow direction of the fluid, and the electrification sequence of the separated electrode modules is set according to the flow direction. In the initial state, the first separated electrode module corresponding to the starting point is energized, and the piezoelectric layer area covered by the energized separated electrode module is deformed. After the piezoelectric layer area is deformed, the corresponding elastic layer area is separated from the substrate to form a cavity, and the fluid From the fluid channel into the cavity; the area covered by the separation electrode module that is not electrified, and the elastic layer are kept attached to the substrate in a cut-off state. Then, the second separated electrode module is energized, the piezoelectric layer area and the elastic layer area covered by the second separated electrode module deform the volume cavity, and the cavity of the first separated electrode module and the cavity of the second separated electrode module There is overlap end to end, and the fluid flows into the cavity of the second split electrode module. Then, the first separated electrode module is de-energized and reaches the cut-off state, the fluid completely leaves the cavity of the first separated electrode module, and at the same time, the third separated electrode module is powered on, and the piezoelectric layer covered by the third separated electrode module The region and the elastic layer region are deformable cavities, and the fluid is located in the cavities of the second separated electrode module and the third separated electrode module. Then the second split electrode module is de-energized, the fourth is energized, and so on until the penultimate split-electrode module and the last split-electrode module are energized, the rest of the split-electrode modules are de-energized, and the fluid enters the terminal fluid channel. Then, the penultimate separated electrode module and the last separated electrode module are de-energized in turn, and the fluid delivered at one time completely enters the fluid channel at the end point. Then the first separated electrode module at the starting point is energized to start the next fluid delivery, and so on until the fluid delivery is completed.

Further, the central axis of the fluid channel is aligned with the center of its corresponding separated electrode module.

Further, the number of separated electrode modules is at least three, and the number of separated electrode modules is variable. The number of separate electrode modules may be determined according to the distance between two fluid channels. The distance between adjacent separated electrode modules only needs to allow the cavities of adjacent separated electrode modules to overlap.

The advantages of the present invention are:

1. The piezoelectric layer area covered by the un-energized separation electrode module does not deform, and the elastic layer area covered by the un-energized separation electrode module adheres to the substrate. These areas are in a cut-off state, and the fluid can only flow from The flow in the cavity of the separated electrode module can effectively prevent the fluid from flowing backward.

2. Since the elastic layer is set to fit the substrate, the pump body formed by the separated electrode module, the piezoelectric layer, the lower electrode and the elastic layer, when the separated electrode module is de-energized, the elastic layer is bonded to the substrate, and the dead zone of the cavity Almost 0, almost 100% of the fluid entering the cavity is transmitted out, and the transmission efficiency is high.

3. The upper electrode is composed of multiple separated electrode modules, and the area covered by each separated electrode module forms a unit capable of independent deformation. Multiple separated electrode modules, a piezoelectric layer and a lower electrode are equivalent to multiple piezoelectric implementations The unit is integrated into a piezoelectric actuator, the structure is simpler; the installation is more convenient and the cost is lower.

4. The cavity containing the fluid is formed entirely by the deformation of the piezoelectric actuator unit. There is no need to pre-set grooves on the substrate to accommodate the fluid. The contact surface between the substrate and the elastic layer is a plane, and the manufacturing process of the substrate is simple; and the plane of the substrate The cavity in the deformed area is just sealed when it is attached to the elastic layer, and no other sealing measures are required for the cavity.

5. The two fluid channels do not need to add valve bodies, so the two fluid channels can be used as the starting point or the end point of the fluid flow path, and the two-way transmission of the fluid can be realized by controlling the order in which the separated electrode modules are powered on.

Description of drawings

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

FIG. 2 is a top view of FIG. 1 .

Fig. 3 is a schematic diagram of the bonding area between the actuator and the substrate according to the present invention, and the grid area is the bonding area.

Fig. 4 is a working principle diagram of the piezoelectric peristaltic micropump of the present invention.

Fig. 5 is a voltage flow chart of the separated electrodes of the present invention.

Fig. 6 is a working flowchart of the piezoelectric peristaltic micropump of the present invention.

Detailed ways

As shown in Figures 1 and 2, a piezoelectric peristaltic micropump includes a substrate 2 and a piezoelectric actuator. The substrate 2 is provided with fluid channels 41 and 42. The number of fluid channels is two, and one fluid channel is used as a delivery path. The starting point of another fluid channel as the end of the delivery path;

The piezoelectric actuator is mainly composed of a piezoelectric layer 11, an upper electrode 13, a lower electrode 14, and an elastic layer 12. The lower electrode 14 completely covers the piezoelectric layer 11, and the upper electrode 13, piezoelectric layer 11, lower electrode 14, and elastic layer 12 Arranged sequentially from top to bottom, the outer frame portion 32 of the elastic layer 12 is sealed and fixed to the substrate 2, the area inside the outer frame portion 32 of the elastic layer 12 is the pump cavity portion 31, the upper electrode 13, the lower electrode 14 and the piezoelectric layer 11 is located in the region of the pump chamber part 31; the upper electrode 13 is composed of a plurality of separate electrode modules, the separate electrode modules are arranged equidistantly along the conveying path, and the first separate electrode module and the last separate electrode module correspond to a fluid channel 41, 42. When the separated electrode module is energized, a cavity is formed between the energized separated electrode module and the base body 2. When the separated electrode module is de-energized, the de-energized separated electrode module is attached to the base body 2; The cavity formed by the electrode modules overlaps from the beginning to the end, and the separated electrode modules are energized sequentially from the starting point to the end point of the conveying path.

In this embodiment, the piezoelectric layer 11 is a square piezoelectric ceramic sheet with a length of 25 mm, a width of 5 mm, and a thickness of 50 microns. The length and width of the piezoelectric layer 11 should be able to completely cover the pump cavity 31 of the substrate, and the thickness of the piezoelectric layer 11 should be able to drive the deformation of the elastic layer 12, and are not limited to the specific dimensions of this embodiment.

The lower electrode 14 is a monolithic electrode having the same shape as the piezoelectric layer 11 . The upper surface of the piezoelectric layer 11 covers a row of separated electrode modules 13, and the upper electrode 13 and the lower electrode 14 are both silver electrodes with a thickness of 1 micron. In this embodiment, there are four separate electrode modules, respectively 131, 132, 133, and 134, so that the piezoelectric actuator is divided into four execution units. The separated electrode module is a square with a side length of 4 mm. The elastic layer 12 is a stainless steel sheet with a length of 25 mm, a width of 8 mm, and a thickness of 50 microns. The piezoelectric layer 11 and the elastic layer 12 are bonded by epoxy glue, and the glue layer is about 1 micron. Although the glue layer is not shown in the figure, how to bond the glue layer is a common method.

The substrate is a plexiglass sheet with a length of 25 mm, a width of 8 mm, and a thickness of 2 mm. Two fluid channels 41 and 42 run through the substrate with a diameter of 1 mm. Two fluid channels 41 and 42 are respectively located under the separated electrode modules 131 and 134 at both ends. The elastic layer 12 of the piezoelectric actuator is bonded to the base body 2 in the edge region. As shown in FIG. 3 , the edge grid area is the outer frame portion 32 of the elastic layer, and the elastic layer 12 can be bonded to the base 2 with epoxy glue. The middle area is the pump chamber part 31, and the separated electrode module in the non-working state without power is bonded to the substrate, which can effectively prevent fluid backflow.

Figure 4 is a schematic diagram of the working principle of the piezoelectric peristaltic micropump. When the lower electrode is grounded and a voltage is applied to the separated electrode module 131, a local bending deformation occurs at the separated electrode module 131, so that a cavity 311 is formed between the area covered by the separated electrode module 131 and the substrate 2. Due to the negative pressure, the external fluid will is filled into cavity 311 as indicated by the arrow. When the voltage drops to 0, the area covered by the separated electrode module 131 recovers and deforms, and the fluid in the cavity 311 will be squeezed to flow into the cavity formed by the next separated electrode module 132 . As long as voltages are applied to the separated electrode modules in a certain order, the cavities generated by the separated electrode modules can move from one fluid channel to another fluid channel to realize fluid delivery. The structure of the micropump is symmetrical, and the control of the fluid flow direction can be realized by controlling the application sequence of the voltage.

Fig. 5 and Fig. 6 are respectively the voltage flow chart of the separated electrode module and the working flow chart of the micropump according to the present invention. The whole workflow is divided into 4 steps. Step 1: Apply voltage to the separated electrode modules 131 and 134, and the voltage to the separated electrode modules 132 and 133 is 0, as shown in FIG. 5 . At this time, the piezoelectric layer 11 covered by the separated electrode modules 131 and 134 is partially deformed, as shown in FIG. 6 , the dotted line represents the position of the upper surface of the substrate, the solid line represents the offset generated by the actuator, and the arrow represents the fluid flow direction. Fluid flows from the fluid channel 41 into the cavity 311 at the separated electrode module 131 . Step 2: Voltage is applied to the separated electrode modules 131 and 132 , the voltage of the separated electrode modules 133 and 134 is 0, a cavity is also generated at the separated electrode module 132 , and the fluid flows to 132 . At this time, the voltage of the separation electrode module 134 becomes 0, and the volume of the cavity at this place becomes 0. Since the separation electrode module 133 is cut off, the fluid flows out from the fluid channel 42 . Step 3: The voltage of the separated electrode module 131 becomes 0, the separated electrode module 133 applies a voltage, and the separated electrode module 134 maintains a voltage of 0, so the fluid at the separated electrode modules 131 and 132 flows to the separated electrode modules 132 and 133. Step 4: The voltage of the separated electrode module 131 is kept at 0, the voltage drop of the separated electrode module 132 is 0, and the voltage is applied to the separated electrode modules 133 and 134, so the fluid originally at the separated electrode modules 132 and 133 flows to the separated electrode modules 133 and 134. Repeating steps 1 to 4, the fluid will be input from the fluid channel 41 and flow out from the fluid channel 42 continuously. Since the two fluid channels can be used as the starting point or the end point according to the flow path of the fluid, if the voltage application sequence of the separated electrode modules 131 and 134 is reversed, and the voltage applied sequence of the separated electrode modules 132 and 133 is reversed, the fluid will flow from the fluid channel 42 flows to fluid channel 41. The flow rate of the fluid can be determined by the magnitude of the applied voltage and the speed of steps 1 to 4. The greater the voltage, the faster the flow rate, and the faster the speed of steps 1 to 4, the greater the flow rate.

The content described in the embodiments of this specification is only an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments. Equivalent technical means that a person can think of based on the concept of the present invention.

Claims (4)

1. A piezoelectric peristaltic micropump, comprising a base body and a piezoelectric actuator, offers a fluid channel on the base body, and is characterized in that: the quantity of the fluid channel is two, one fluid channel is used as the starting point of the delivery path, and the other fluid channel is used as the starting point of the delivery path. The end of the conveying path; the piezoelectric actuator is mainly composed of a piezoelectric layer, an upper electrode, a lower electrode and an elastic layer, the lower electrode completely covers the piezoelectric layer, and the upper electrode, piezoelectric layer, lower electrode and elastic layer are sequentially from top to bottom Setting, the outer frame of the elastic layer is sealed and fixed with the substrate, and the area inside the outer frame of the elastic layer is the pump chamber; the upper electrode is composed of a plurality of separated electrode modules, the first separated electrode module and the last separated electrode module Each corresponds to a fluid channel; when the separation electrode module is energized, a cavity is formed between the energized separation electrode module and the substrate; when the separation electrode module is de-energized, the de-energized separation electrode module is bonded to the substrate; The cavities formed by the separated electrode modules are overlapping from the beginning to the end, and the separated electrode modules are energized sequentially from the starting point to the ending point of the conveying path. 2. The piezoelectric peristaltic micropump according to claim 1, wherein the separated electrode modules are arranged equidistantly along the conveying path. 3. The piezoelectric peristaltic micropump according to claim 2, wherein the central axis of the fluid channel is aligned with the center of its corresponding separation electrode module. 4. The piezoelectric peristaltic micropump according to any one of claims 1-3, wherein the number of separated electrode modules is at least three.