CN105214546B - A kind of concussion jetting type micro-mixer based on Pulsating Flow - Google Patents

Abstract

An oscillating jet micromixer based on pulsating flow, the micromixer includes a glass cover plate and a lower substrate; the glass cover plate and the lower substrate are connected by high-temperature bonding to form a micromixer. The invention combines the advantages of the passive micro-mixer and the active micro-mixer, can effectively improve the efficiency of the micro-mixer, and solves the defects of single mixing mechanism and high processing difficulty of the existing micro-mixer. The present invention mainly applies a pulsating flow with a sawtooth-shaped flow velocity to a fluid at two symmetrical inlets of the micro-mixer to promote the mixed fluid to oscillate; Increase the perturbation intensity to achieve thorough mixing of fluids at the microscale. The micro-mixer has the advantages of easy processing structure, low cost, high mixing efficiency and the like.

Description

An Oscillating Jet Micromixer Based on Pulsating Flow

technical field

The present invention provides a novel micro-mixer that can be used to improve the mixing efficiency of different reactants. The interior of the mixer has the characteristics of chaotic convection, which can realize the rapid fusion of various fluids at the micro scale. The invention relates to technical fields such as life science and chemical industry, and in particular relates to a micro-mixer.

Background technique

The goal of the miniature full analysis system is to concentrate the sampling, mixing, dilution, sample addition, reaction, separation and detection functions of the entire chemical laboratory on one chip, so as to save reaction reagents to the greatest extent and reduce the risk of the analysis process ( Such as highly toxic or flammable and explosive reagents), improve the analysis efficiency, and also have the advantages of easy miniaturization and automation. Due to the above advantages, the application prospect of this technology is extremely broad.

At the macroscopic scale, most fluids are in a state of turbulent flow, and complete mixing between different fluids can be quickly achieved through turbulent flow. However, at the microscale, the ratio of the surface area to volume of the fluid inside the microfluidic chip increases sharply, and the surface force and viscous force The effect of the dominant force, the effect of the inertial force is rapidly reduced, so that the flow of the fluid inside the microchannel is mainly laminar flow, and it is difficult to mix quickly and efficiently in the microfluidic device. Therefore, relying solely on molecular diffusion cannot meet the needs of modern biological and chemical analysis with fast reaction speed, low drug dosage, rapid analysis and real-time detection. In order to achieve efficient and uniform mixing of reactants under micro-scale conditions, micro-mixers came into being.

According to whether there is external energy to drive the micro-mixer, it can be divided into two categories: one is the active micro-mixer, and the other is the passive micro-mixer. The former mechanism is to achieve the effect of mixing through the relative motion between the liquids generated by the action of the external field. The mechanism of the passive micro-mixer mainly relies on changing the internal structure and shape of the pipeline to increase the mixing area as much as possible to achieve the effect of enhanced mixing. Studies on passive mixers have shown that flow phenomena such as chaotic flow, secondary flow, and vortex structure can effectively increase the contact area between fluids and promote the mixing of liquids. Among them, there are many ways to realize chaotic convection and vortex structure, such as improving channel structure and periodically changing flow.

Contents of the invention

The invention combines the advantages of the passive micro-mixer and the active micro-mixer, can effectively improve the efficiency of the micro-mixer, and solves the defects of single mixing mechanism and high processing difficulty of the existing micro-mixer. The present invention mainly applies a pulsating flow with a sawtooth-shaped flow velocity to a fluid at the inlet of the micro-mixer to promote the mixed fluid to oscillate; and increases the disturbance intensity by means of the secondary mixing chamber, branch structure, and zigzag structure. , to achieve full mixing of fluids at the microscale. The micro-mixer has the advantages of easy processing structure, low cost, high mixing efficiency and the like.

The technical scheme adopted in the present invention is as follows, a oscillating jet micro-mixer based on pulsating flow, the micro-mixer includes a glass cover plate (11), a lower substrate (12), wherein the lower substrate is engraved with a micro-mixer channel; the glass cover The surface of the plate (11) and the lower substrate (12) is connected by high-temperature bonding to form a micro-mixer (13).

The glass cover plate (11) is made of high-transparency material to facilitate the observation of the flow inside the micro-mixer and to play a role of sealing.

The micro-mixer channel in the lower substrate (12) is a variated drop-shaped structure, and the bottom and top of the variated water-drop-shaped structure and the connection between the two are arc-shaped curves, wherein the curvature of the bottom is greater than that of the top curvature. The lower substrate (12) is in the form of multiple inlet channels, in order to realize the mixing of various fluids; the number of inlet channels is greater than or equal to three; the preferred number of inlet channels is three, namely the inlet channel a (1), the inlet channel b ( 2), entrance channel c (3). Wherein, the entrance channel a (1), the entrance channel b (2), and the entrance channel c (3) are evenly and symmetrically distributed. The ends of the above-mentioned inlet passages are connected to the two ends of the outlet passage (10) through the nozzle-like structure (4) to form a mixing chamber structure. The mixing chamber structure is divided into upper, middle and lower parts. The upper part of the mixing chamber structure is the first A mixing chamber (5), with a strip-shaped branch structure (6) in the middle, a second mixing chamber (7) in the lower part and a cylindrical flow blocking structure (8) in the second mixing chamber (7), the second The second mixing chamber (7) is connected with the outlet channel (10), and the outlet channel (10) is provided with a zigzag structure (9).

The inlet channel a(1), inlet channel b(2), and inlet channel c(3) are schematic structures, and the two fluids are mixed on the premise; ) to add a branch structure.

The inlet channel b(2), inlet channel c(3) width and fluid inflow angle depend on fluid mixing requirements.

The height of the first mixing chamber (5) from the jet inlet is 5-10 times the width of the inlet channel.

The number of branches in the middle of the mixing chamber can be increased as required, and the minimum width of the branches is not less than 20 μm to facilitate processing.

The diameter of the cylindrical baffle structure (8) is larger than the width of the outlet passage (10), and it is placed on the center line of the inlet passage to ensure the baffle effect.

The number of zigzag structures (9) in the outlet channel (10) is appropriately increased as required, and theoretically, the greater the number, the better the mixing effect, but the corresponding flow resistance also increases accordingly.

The working process of the present invention is as follows, wherein one kind of fluid flows in through the inlet channel a(1), and another kind of fluid flows in through the inlet channel b(2) and the inlet channel c(3) at different wave speeds. The three streams of fluid are respectively accelerated by the nozzle structure to form regular jets and flow into the first mixing chamber of the micro-mixer; in the first mixing chamber, the three jets meet to form jet oscillations and perform pre-mixing. The oscillating jet enters the middle of the mixing chamber after pre-mixing, and enters the strip-shaped branch structure for intensified mixing. The fluids that have been intensively mixed through each branch flow together in the second mixing chamber, and a cylindrical baffle structure is arranged in the chamber to increase the mixing time and mixing intensity of the branch flows in the chamber. The fluid enters the outlet channel through the second mixing chamber, and the zigzag structure inside the channel helps to form a vortex structure and chaotic convection in the fluid, further strengthening the mixing.

Compared with the prior art, the present invention has the following beneficial effects.

1. Introduce pulsating flow at the inlet channel of this type of mixer, which helps to induce chaotic convection in the channel and promote mixing.

2. In the micro-mixer, the mixing chamber is designed as a drop-shaped structure. Under the premise of pulsating flow, this structure can form jet oscillation and strengthen mixing.

3. In the mixer, the strip branch structure, baffle structure and zigzag structure can effectively increase the unbalanced collision between fluid molecules and improve the mixing efficiency of reactants.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of a glass cover plate of the present invention.

Fig. 2 is a three-dimensional schematic diagram of the flow channel inside the micro-mixer of the present invention.

Fig. 3 is a top view of the micro-mixer of the present invention.

Fig. 4 is a three-dimensional schematic diagram of the assembly of the micro-mixer of the present invention.

Fig. 5 is a flow velocity wave diagram of inlet channel b and inlet channel c of the present invention.

In the figure: 1. Inlet channel a, 2. Inlet channel b, 3. Inlet channel c, 4. Nozzle-like structure, 5. First mixing chamber, 6. Strip branch structure, 7. Second mixing chamber, 8 . Cylindrical flow blocking structure, 9. Zigzag structure, 10. Micro mixer outlet channel, 11. Glass cover plate, 12. Lower substrate, 13. Micro mixer.

Detailed ways

1. Processing requirements

a) The material of this kind of micro-mixer is made of glass material, PDMS and other transparent materials, and the processing method adopts the method of chemical etching. The external conduits at the entrance and exit of the channel can use Teflon plastic hose. Pay attention to the bonding quality between the glass plate and the underlying substrate to ensure the hermeticity of the system.

b) This kind of micro-mixer can realize the mixing of various fluids, and multiple inlet channels can be provided, and only three inlet channels are provided for the convenience of explanation in the text. Therefore, if it is necessary to increase the mixing number of fluid types in actual design, a branch structure can be added at the inlet channel a(1) to meet the requirements of actual working conditions.

c) The width of the inlet channel b(2), the inlet channel c(3) and the inflow angle can be changed according to the mixing requirements.

d) The first mixing chamber needs to maintain an appropriate height, generally the height from the jet inlet is 5 to 10 times the width of the inlet channel.

e) The number of branch structures in the middle of the mixing chamber can be increased as required, and generally the minimum width is not less than 20 μm (facilitating processing).

f) The diameter of the cylindrical baffle structure should be greater than the width of the outlet channel, and it must be placed on the center line of the inlet channel to ensure the effect of turbulence.

g) The number of zigzag structures (9) in the outlet channel (10) can be appropriately increased according to needs. Theoretically, the more the number, the better the mixing effect, but the corresponding flow resistance will also increase accordingly.

2. Requirements for flow input (take the uniform mixing of two fluids as an example)

The following principles must be followed for the flow rate (speed) through the entrance channel a (1), the entrance channel b (2), and the entrance channel b (3):

a) The flow (velocity) in the inlet channel a(1) is kept constant.

b) The inlet channel b(2) and the inlet channel c(3) are pulsating flows respectively, and the inlet velocities of the inlet channel b(2) and the inlet channel c(3) can refer to FIG. 5 . If it needs to be changed, please follow the following principles: the phase difference of the flow velocity of inlet channel b(2) and inlet channel c(3) must be guaranteed to be 180°, and the smaller the pulsation frequency, the better.

Claims (7)

1. A oscillating jet micromixer based on pulsating flow, characterized in that: the micromixer comprises glass cover plate (11), lower substrate (12); the surface of glass cover plate (11) and lower substrate (12) High-temperature bonding is used to form a micro-mixer (13); The glass cover plate (11) is made of a high-transparency material to facilitate the observation of the flow inside the micro-mixer and to play a role in sealing; The micro-mixer channel in the lower substrate (12) is a variated drop-shaped structure, and the bottom and top of the variated water-drop-shaped structure and the connection between the two are arc-shaped curves, wherein the curvature of the bottom is greater than that of the top Curvature; the lower substrate (12) is in the form of multiple inlet channels, in order to realize the mixing of multiple fluids; the number of inlet channels is greater than or equal to three; the number of inlet channels is three, that is, inlet channel a (1), inlet channel b (2), inlet channel c (3); wherein the inlet channel a (1), the inlet channel b (2), and the inlet channel c (3) are evenly and symmetrically distributed; the ends of the above-mentioned inlet channels pass through the nozzle-like structure (4) and The two ends of the outlet channel (10) are connected to form a mixing chamber structure. The mixing chamber structure is divided into upper, middle and lower parts. The upper part of the mixing chamber structure is the first mixing chamber (5), and the middle part is provided with a strip branch structure (6), the bottom is provided with a second mixing chamber (7) and a cylindrical flow blocking structure (8) is provided in the second mixing chamber (7), the second mixing chamber (7) is connected with the outlet channel (10), And a zigzag structure (9) is provided in the outlet channel (10). 2. A kind of oscillating jet micro-mixer based on pulsating flow according to claim 1, characterized in that: the inlet channel a (1), the inlet channel b (2), the inlet channel c (3) in two kinds Fluid mixing is the premise; if it is necessary to increase the mixing number of fluid types, add a branch structure at the inlet channel a(1). 3. A kind of oscillating jet type micro-mixer based on pulsating flow according to claim 1, characterized in that: the width of the inlet passage b (2), the inlet passage c (3) and the inflow angle of the fluid depend on the mixing of the fluid Require. 4. An oscillating jet micro-mixer based on pulsating flow according to claim 1, characterized in that the height of the first mixing chamber (5) from the jet inlet is 5-10 times the width of the inlet channel. 5. An oscillating jet micro-mixer based on pulsating flow according to claim 1, characterized in that: the number of branches in the middle of the mixing chamber can be increased as required, and the minimum width of the branches is not less than 20 μm. 6. A kind of oscillating jet type micro-mixer based on pulsating flow according to claim 1, characterized in that: the diameter of the cylindrical baffle structure (8) is greater than the width of the outlet passage (10), and placed in the inlet passage center line. 7. The oscillating jet micro-mixer based on pulsating flow according to claim 1, characterized in that: the number of zigzag structures (9) in the outlet channel (10) is appropriately increased as needed, and the more the number is theoretically mixed The better the effect, but the corresponding flow resistance will also increase.