CN111946897A - A thin film deformation microfluidic device - Google Patents

Abstract

The invention discloses a thin film deformation microfluidic device, comprising an upper clamp and a lower clamp, a film deformation unit is installed between the upper clamp and the lower clamp, and the film deformation unit is composed of a fluid control layer, a film deformation layer, a fluid flow resistance layer and a The fluid outlet layer is stacked, the fluid control layer is provided with a first fluid channel and a central fluid extrusion chamber, the film deformation layer is provided with a second fluid channel, and the fluid flow resistance layer is provided with a third fluid channel and a central flow resistance The adjustment chamber, the fluid outlet layer is provided with a fluid outlet channel, the first fluid channel is connected to the third fluid channel through the second fluid channel, the upper fixture is provided with a fluid sampling interface and a fluid sampling channel, and the center of the bottom of the lower fixture is provided with There is a fluid outlet. The device can self-regulate the flow rate through film deformation, realize unstable fluid input, stable flow rate output, precise device structure, and can meet different precise sample output requirements, with low cost, simple operation, and easy integration and miniaturization.

Description

A thin film deformation microfluidic device

technical field

The present invention relates to a microfluidic device, more particularly, to a thin film deformation microfluidic device.

Background technique

Microvalves are very important in microfluidic applications. Many microfluidic valves with different structures and functions have been developed and applied to on-chip devices. According to the working principle of microvalves, microvalves can be divided into two types: active and passive. kind. Active valves usually use external actuators, which can precisely control liquids. Therefore, in the large-scale integration of microfluidic devices, active valves have a high degree of compatibility, but external actuators also increase the complexity of the valve control system and are not suitable for True miniaturization of complex systems. While passive valves can effectively control flow in microfluidic systems, which do not require complex actuators, passive valves can be used in low-cost and portable microfluidic applications. Passive valves include capillary passive valves and membrane deformation valves. Since the capillary force depends on the cohesion of liquid molecules and the adhesion between the liquid and the microchannel, the liquid flow rate can be adjusted by adjusting the surface hydrophobicity of the microfluidic structure, However, the flow rate due to capillary force is relatively low and can only be applied for a limited time. In addition, capillary force is usually unstable, which also limits its application in biochemical analysis; while the membrane deformation valve mainly works by changing the microchannel flow resistance to adjust the flow. A membrane valve usually consists of two channels, including a flow channel and a control channel, separated by an elastic membrane. When the liquid enters the flow channel and the control channel at the same time, the control channel exerts pressure to deform the membrane, thereby changing the flow resistance of the flow channel to adjust the flow rate, but it still has the problem of poor reusability of the micro valve and large flow fluctuation. question.

SUMMARY OF THE INVENTION

Purpose of the invention: The purpose of the present invention is to provide a thin-film deformation microfluidic device capable of realizing unstable fluid input, stable flow rate output, and flow self-regulation.

Technical scheme: The thin film deformation microfluidic device described in the present invention includes an upper clamp and a lower clamp, and a film deformation unit is installed between the upper clamp and the lower clamp, and the film deformation unit is composed of a fluid control layer, a film deformation layer, a fluid flow The resistance layer and the fluid outlet layer are stacked, the fluid control layer is provided with a first fluid channel and a central fluid extrusion chamber, the film deformation layer is provided with a second fluid channel, and the fluid flow resistance layer is provided with a third fluid channel and The central flow resistance adjustment chamber, the fluid outlet layer is provided with a fluid outlet channel, the first fluid channel passes through the second fluid channel to the third fluid channel, the upper fixture is provided with a fluid sampling interface and a fluid sampling channel, and the lower fixture is provided with There is a fluid outlet in the center of the bottom.

The thickness of the film deformation layer is 10-50 μm, the thickness of the fluid control layer is 200±50 μm, and the thickness of the fluid flow resistance layer is 125±25 μm; a fluid with a height of 200-500 μm is arranged between the upper clamp and the top layer of the film deformation unit The extrusion chamber; the first fluid channel, the second fluid channel and the third fluid channel are arranged in an annular array, the third fluid channel leads to the central flow resistance adjustment chamber, and the central flow resistance adjustment chamber is 0.5-1.7 in diameter mm, a cylindrical cavity with a height of 25-200 μm, and the diameter of the fluid outlet channel is 0.1-1 mm. After the liquid is injected, under the extrusion of the film deformation layer, the volume between the outlet and the outlet decreases, thereby increasing the overall device flow resistance. , the fluid outlet channel is smaller than the central flow resistance adjustment chamber, which cooperates with the central flow resistance adjustment chamber and the film deformation layer to form a negative feedback system for the change of flow resistance; Fast installation and fast fluid injection; an annular blocking block is set on the upper fixture, and the annular blocking block and the annular sealing block set on the lower fixture fix and seal the fluid control layer; the fluid control layer and the fluid flow resistance layer are silica gel or any A material that can bond with PDMS or PEGDA, the film deformation layer is PDMS or PEGDA, the fluid outlet layer material is silica gel or any film material that can bond with silica gel, fluid control layer, film deformation layer, fluid flow resistance The layer and the fluid outlet layer are bonded into a whole by a plasma cleaning method, and the surfaces of the fluid control layer, the thin film deformation layer, the fluid flow resistance layer and the fluid outlet layer are exposed to the oxygen plasma by a plasma cleaning machine, and their surfaces are CH ₃ and _CH2 functional groups are depleted while enriching their surfaces with silanol Si-OH groups, and when the two bonding surfaces contact each other, the silanol groups on the opposite surfaces undergo a condensation reaction, forming between these surfaces Permanent bonding; the fluid control layer, film deformation layer, fluid flow resistance layer and fluid outlet layer are processed by laser to obtain the required structure; the upper and lower fixtures are engineering plastics, photosensitive resins, rubber materials, metal materials, and ceramic materials through 3D The printed material is able to withstand the clamping force required for film clamping.

Working principle: The fluid is input into the device through a syringe, and the fluid enters the fluid extrusion chamber between the upper fixture and the film deformation layer through the fluid injection interface and the fluid injection channel. At this time, there is pressure on the upper surface of the film deformation unit, which is named as P _t ; when the fluid enters the central flow resistance adjustment chamber through the second fluid channel of the membrane deformation unit, it can be known from Bernoulli’s equation that the pressure P _d under the membrane deformation layer of the membrane deformation unit is smaller than P _t , because the membrane deformation The pressure difference between the upper and lower layers of the film causes the film deformation layer to sag downward; because the volume of the central flow resistance adjustment chamber below the film deformation layer decreases, its flow resistance increases correspondingly, resulting in a decrease in the flow velocity there, and the film deformation layer The lower pressure P _d increases, forming a negative feedback system between the fluid pressure and the flow resistance of the device, and this system will cause the flow rate to be controlled within a very small fluctuation range, thus achieving a stable flow output.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. It can dynamically change the overall flow resistance of the device through the deformation of the film, carry out self-regulation of the flow, and realize the input of unstable fluid and the output of stable flow rate; 2. The use of laser The processing, bonding process and 3D printing method make the obtained device structure accurate and can meet different precise sample output requirements; 3. Low cost, simple operation, easy integration and miniaturization.

Description of drawings

Fig. 1 is the perspective view of the present invention;

Fig. 2 is the half-section structure schematic diagram of the present invention;

Fig. 3 is a schematic diagram of the structure of the upper clamp;

Fig. 4 is a schematic diagram of the structure of the film deformation unit;

Fig. 5 is the structural representation of lower clamp;

Fig. 6 is the distribution diagram of fluid entity;

Figure 7 is the flow field simulation result;

Figure 8 is a diagram showing the relationship between flow field simulation flow output and pressure input.

Detailed ways

Example 1

As shown in FIG. 1 and FIG. 2 , the thin film deformation microfluidic device includes an upper clamp 9 and a lower clamp 10, and a film deformation unit 5 is installed between the upper clamp 9 and the lower clamp 10. As shown in FIG. 4, the film deforms Unit 5 is formed by stacking a fluid control layer 11 with a thickness of 200 μm, a thin film deformation layer 12 with a thickness of 30 μm, a fluid flow resistance layer 13 with a thickness of 150 μm, and a fluid outlet layer 14 with a thickness of 150 μm. 8 first fluid channels 15 arranged in an annular array and a central fluid extrusion chamber, 8 second fluid channels 16 arranged in an annular array are arranged on the film deformation layer 12, and 8 annular arrays are arranged on the fluid flow resistance layer 13. The third fluid channel 17 arranged in an array leads to the central flow resistance adjustment chamber 7, the fluid outlet layer 14 is provided with a fluid outlet channel 18, and the central flow resistance adjustment chamber 7 is a cylindrical hollow with a diameter of 1.5mm. The cavity, the height is 120 μm, the diameter of the fluid outlet channel 18 is 0.5 mm, the first fluid channel 15 is connected to the third fluid channel 17 through the second fluid channel 16, as shown in FIG. 3, the upper fixture 9 is provided with a fluid sampling interface 1 and fluid injection channel 2, the inner diameter of the fluid injection interface 1 is 1.2mm, which is similar to the outer diameter of a 20mL syringe, the fluid injection interface 1 is an interference fit with the syringe, the bottom center of the lower fixture 10 is provided with a fluid outlet 8, and the upper fixture 9 A fluid extrusion chamber 3 with a height of 300 μm is arranged between it and the top layer of the film deformation unit 5. As shown in FIG. 3 and FIG. The set annular sealing block 6 fixes and seals the fluid control layer 11. As shown in FIG. 6, the fluid is injected into the fluid sampling interface 1 through a syringe, and the fluid enters the upper fixture 9 through the fluid sampling interface 1 and the fluid sampling channel 2. The fluid between the film deformation layer 12 squeezes the chamber 3, and part of the liquid passes through the eight second fluid channels 16 and the third fluid channel 17 in the annular array and enters the central flow resistance adjustment chamber 7 under the film deformation layer 12, Part of the fluid is in contact with the film deformation layer 12. At this time, there is pressure on the upper surface of the film deformation unit 12, which is named P _t ; when the fluid enters the central flow resistance adjustment chamber through the second fluid channel 16 of the film deformation unit 12, it is Bernoulli equation shows that the pressure P _d under the film deformation layer 12 of the film deformation unit 5 is smaller than P _t at this time. Due to the pressure difference between the upper and lower layers of the film deformation layer 12 , the film deformation layer 12 is dented downward; The volume of the cavity of the central flow resistance adjustment chamber 7 decreases, and its flow resistance increases correspondingly at the same time, resulting in a decrease in the flow velocity there, and an increase in the pressure P _d under the film deformation layer 12, forming a gap between the fluid pressure and the flow resistance of the device. Negative feedback system, and this system will cause the flow rate to be controlled in a very small fluctuation range, thus achieving a stable output of the flow. The flow field simulation results are shown in Figure 7. The fluid squeezes the pressure of the chamber 3 and the flow resistance adjustment chamber 7. The difference will result in the downward depression of the film deformation layer 12; the flow rate self-regulating process. As shown in Figure 8, the relationship between the flow output Q and the pressure input P under this size is obtained through comsol simulation. It can be seen from the figure that when the input pressure is between 300-500Pa ^, the flow rate is stable at 2.22±0.04×10- ⁶ m ² /s; the dimensional design parameters of the flow regulating microvalve are qualitatively described by the following formula:

Among them, R is the overall flow resistance of the micro-valve, d _control is the cylinder diameter of the central flow resistance adjustment chamber 7; h is the height of the central flow resistance adjustment chamber 7; t is the thickness of the thin film deformation layer 12; d _out is the fluid outlet channel 18 diameter; the input pressure range of this embodiment is 300-500Pa.

Example 2

The difference between this embodiment and Embodiment 1 is that the diameter of the cylinder of the central flow resistance adjusting chamber 7 is 300 μm and the height is 50 μm, the thickness of the film deformation layer 12 is 20 μm, the diameter of the fluid outlet channel 18 is 100 μm, and the input pressure range is 100kPa±20kPa, its flow output is 6.6629×10 ^-8 m ² /s.

Claims (9)

1. The film deformation microfluidic device is characterized by comprising an upper clamp (9) and a lower clamp (10), wherein a film deformation unit (5) is installed between the upper clamp (9) and the lower clamp (10), the film deformation unit (5) is formed by stacking a fluid control layer (11), a film deformation layer (12), a fluid flow resistance layer (13) and a fluid outlet layer (14), a first fluid channel (15) and a central fluid extrusion chamber are arranged on the fluid control layer (11), a second fluid channel (16) is arranged on the film deformation layer (12), the fluid flow resistance layer (13) is provided with a third fluid channel (17) and a central fluid resistance regulation chamber (7), a fluid outlet channel (18) is arranged on the fluid outlet layer (14), the first fluid channel (15) is communicated to the third fluid channel (17) through the second fluid channel (16), the upper clamp (9) is provided with a fluid sample inlet interface (1) and a fluid sample inlet channel (2), and the center of the bottom of the lower clamp (10) is provided with a fluid outlet (8).

2. The thin film deforming microfluidic device of claim 1, wherein the thin film deforming layer (12) has a thickness of 10 to 50 μm, the fluid control layer (11) has a thickness of 200 ± 50 μm, and the fluid flow resistance layer (13) and the fluid outlet layer (14) have a thickness of 125 ± 25 μm.

3. A thin film deforming microfluidic device according to claim 1 or 2, characterized in that a fluid squeezing chamber (3) with a height of 200-500 μm is provided between the upper clamp (9) and the top layer of the thin film deforming unit (5).

4. The thin film deforming microfluidic device of claim 1, wherein the first fluid channel (15), the second fluid channel (16) and the third fluid channel (17) are arranged in an annular array, the third fluid channel (17) leads to a central flow resistance adjusting chamber (7), the central flow resistance adjusting chamber (7) is a cylindrical cavity with a diameter of 0.5-1.7 mm and a height of 25-200 μm, and the fluid outlet channel (18) has a diameter of 0.1-1 mm.

5. The thin film deforming microfluidic device according to claim 1, wherein an annular blocking block (4) is disposed on the upper fixture (9), and the fluid control layer (11) is fixed and sealed by the annular blocking block (4) and an annular sealing block (6) disposed on the lower fixture (10).

6. The thin film deforming microfluidic device of claim 1, wherein the fluid sample inlet interface (1) is an interference fit with a syringe interface.

7. The thin film deformation microfluidic device according to claim 1, wherein the fluid control layer (11) and the fluid flow resistance layer (13) are silicone or any material capable of bonding with PDMS or PEGDA, the thin film deformation layer (12) is PDMS or PEGDA, the fluid outlet layer (14) is silicone or any material capable of bonding with silicone, and the fluid control layer (11), the thin film deformation layer (12), the fluid flow resistance layer (13) and the fluid outlet layer (14) are bonded into a whole by a plasma cleaning method.

8. Thin-film deforming microfluidic device according to claim 1 or 7, characterized in that the fluid control layer (11), the thin-film deforming layer (12), the fluid flow resistance layer (13) and the fluid outlet layer (14) are laser machined to the desired configuration.

9. The thin film deforming microfluidic device according to claim 1, wherein the upper and lower clamps (9, 10) are made of engineering plastics, photosensitive resins, rubber materials, metal materials, and ceramic materials by 3D printing.

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