CN106362811B - A kind of micro-fluidic chip measuring pressure change in the deformable channel of wall surface - Google Patents

Abstract

The invention discloses a microfluidic control chip for measuring the pressure change in a deformable channel on the wall. The invention indicates the pressure difference on both sides by comparing the displacement and direction of the liquid interface of two channels at the interface. Since the deformable lower wall microchannel needs to add a groove structure on the lower wall of the main channel where the droplets are generated, and limited by the manufacturing accuracy, the width of the groove structure is greater than the width of the main channel of the microchannel structure, so as to form a Complete thin-wall structure, so the upstream of the droplet generation channel and the pressure contrast channel should be designed separately to avoid mutual interference, the droplet generation channel and the pressure contrast channel are 90° broken lines. Since the pressure signal will gradually attenuate during the transmission process, the pressure contrast interface should not be too far away from the place where the droplets meet and generate. The invention uses the displacement direction and size of the interface to indicate the pressure change of the droplet generating channel, the operation method is simple and intuitive, and the experimental effect is stable and reliable.

Description

A microfluidic chip for measuring pressure changes in a channel with deformable walls

technical field

The invention relates to a droplet generation structure based on deformable walls. By improving the side wall structure downstream of droplet generation, adding a comparison channel parallel to the flow direction and a pressure comparison interface, a method for measuring the pressure change in the deformable wall channel is formed. comparative structure.

Background technique

In recent years, microfluidic technology with micro-droplet technology as the core has developed rapidly. The existence of micro-droplets has brought some outstanding advantages, such as small size, large specific surface area, fast speed, high flux, uniform size, closed system, etc. , these advantages make micro-droplet technology has been widely used in physics, chemistry, biology and multidisciplinary fields.

In microdroplet technology, the generation and movement of droplets/bubbles will generate additional pressure, which has a great impact on the pressure and velocity distribution inside the channel, increasing the functionality and complexity of the system. At present, in experiments and engineering, the extra pressure generated by droplets/bubbles is often used to meet different needs. For example, the pressure can be used as a logic signal to control logic gates or logic switches; pressure changes caused by multiple emulsification are also used in oil extraction. Playing a very important role, it is possible to simulate the subterranean porous environment with the help of microdroplet technology and measure this pressure at the laboratory level. In addition, the increased nonlinearity of the two-phase interface in the presence of droplets/bubbles can be used to perturb the laminar flow regime of the system at low Reynolds numbers and enhance the mixing efficiency of the continuous phase. The realization of these functions requires understanding the specific effects of different sizes of droplets/bubbles on system pressure changes under various flow conditions.

There are many methods to measure the pressure at the microscale. The most direct one is to embed miniaturized sensors into microchannels to obtain pressure change data at the measurement point. However, due to the large size of the sensor, it is not compatible with the system. The structure is relatively complex, and the measurement position is limited so that it can only measure the pressure drop of single-phase flow or the total pressure difference of multiple droplets over a distance. This makes it difficult for this method to be well embedded in many devices. On the other hand, in many cases, we will pay more attention to the pressure change trend of the droplet in different states, and it is not necessary to obtain specific values.

Contents of the invention

The present invention is based on the designed T-shaped micro-droplet generating structure with deformable wall surface, changes the side wall surface at the downstream of the converging generating structure, increases the comparison channel and the pressure comparison interface whose flow direction is parallel to the main channel, and compares the liquid in the two channels at the comparison interface The displacement magnitude and direction of the interface can be used to indicate the pressure difference between the two sides.

In order to achieve the above purpose, the technical solution adopted by the present invention is a microfluidic chip for measuring the pressure change in the deformable channel on the wall. The whole microfluidic chip is composed of a cover sheet 1, a film layer 2 and a substrate 3. It is made of PDMS material; in Fig. 1, there is a microchannel structure 4 inside the cover sheet 1, and an opening side is arranged on the microchannel structure 4; the film layer 2 is a flat plane; the inside of the substrate 3 is provided with a groove structure 5, and The slot structure 5 is also provided with an opening side; the opening side on the microchannel structure 4 and the opening side on the groove structure 5 are in direct contact with the film layer 2, and the cover sheet 1, the film layer 2 and the substrate 3 are sequentially matched up and down to form The overall structure of the microfluidic chip is shown in Figure 1.

As shown in Figure 2, the microchannel structure 4 includes a droplet generating part and a pressure contrast part;

The droplet generation part consists of the discrete phase inlet 8, the undyed continuous phase inlet 7, the outlet 12 and the droplet generation channel 9; the pressure contrast part consists of the dyed continuous phase inlet 6, the pressure contrast channel 10 and the outlet 12;

The outlet 12 of the droplet generation part and the outlet 12 of the pressure comparison part are the same; the upstream of the droplet generation channel 9 is connected to the discrete phase inlet 8 and the undyed continuous phase inlet 7, and the downstream of the droplet generation channel 9 is connected to the outlet 12 Connected; the upstream of the pressure contrast channel 10 is connected to the dyed continuous phase inlet 6, and the downstream of the pressure contrast channel 10 is also communicated with the outlet 12; the droplet generation channel 9 and the pressure comparison channel 10 pass through the pressure comparison interface 11 downstream of the droplet generation Connect; the first alignment groove 13 is arranged on the microchannel structure 4, as shown in Figure 3 is the structure on the substrate 3, the second alignment groove 14 is arranged on the groove structure 5; the first alignment groove 13 and The second alignment groove 14 is corresponding to ensure the bonding connection of the cover sheet 1 , the film layer 2 and the substrate 3 .

Since the deformable lower wall microchannel needs to add a groove structure on the lower wall of the main channel where the droplets are generated, and is limited by the manufacturing accuracy, the width of the groove structure is greater than the width of the main channel of the microchannel structure 4 to form the width direction of the main channel. Therefore, the upstream of the droplet generating channel 9 and the pressure contrast channel 10 should be designed separately to avoid mutual interference. The droplet generating channel 9 and the pressure contrast channel 10 are in the shape of a 90° broken line. On the other hand, since the pressure signal will gradually attenuate during the transmission process, in order to measure the pressure change during the droplet generation process, the pressure comparison interface 11 cannot be too far away from the droplet intersection and generation place.

The invention designs a pressure comparison channel and a pressure comparison interface, uses the displacement direction and size of the interface to indicate the pressure change of the droplet generation channel, the operation method is simple and intuitive, and the experimental effect is stable and reliable.

Description of drawings

Fig. 1 is a schematic diagram of a three-dimensional general outline of a microfluidic chip for measuring pressure changes in a wall-deformable channel of the present invention.

Fig. 2 is a schematic diagram of a microchannel structure in a microfluidic chip for measuring pressure changes in a wall deformable channel according to the present invention.

Fig. 3 is a schematic diagram of a groove structure in a microfluidic chip for measuring pressure changes in a deformable channel of the present invention.

Fig. 4 is a diagram of the interface change of the pressure contrast interface at different moments during the droplet generation process and movement process of a microfluidic chip for measuring the pressure change in the wall deformable channel of the present invention. Among them, (a) is the interface diagram when the pressure on both sides of the pressure comparison interface is balanced, (b) is the interface diagram at a certain moment when the droplet is formed, and (c) is the interface diagram at a certain moment when the droplet is moving.

In the figure: 1. cover sheet, 2. film layer, 3. substrate, 4. microchannel structure, 5. groove structure, 6. dyed continuous phase inlet, 7. undyed continuous phase inlet, 8. discrete Phase inlet, 9, droplet generation channel, 10, pressure contrast channel, 11, pressure contrast interface, 12, outlet, 13, first alignment groove, 14, second alignment groove.

Note:

1. The microchannel structure in Figure 1 is a schematic diagram, and the pressure contrast structure in the experiment is shown in Figure 2;

2. The experimental conditions measured by the interface change diagram provided in Figure 4: the pressure of the undyed oil phase is 56 mbar, the pressure of the dyed oil phase is 35 mbar, and the pressure of the discrete phase is 14-17 mbar.

Detailed ways

The working process and effect of the invention of a microfluidic chip for measuring pressure changes in a deformable wall channel will be described in detail below in conjunction with the structural drawings.

The specific working process of this device is as follows: in the droplet generation part, the discrete phase liquid flows in from the discrete phase inlet 8, and the undyed continuous phase liquid flows in from the undyed continuous phase inlet 7, and the two are in the intersection structure of the droplet generation channel 9 meet, the discrete phase liquid breaks up to form droplets and flows downstream together with the continuous phase, and finally flows out of the chip through the outlet 12. In the pressure contrast part, the dyed continuous phase liquid flows in from the dyed continuous phase inlet 6 and flows to the outlet 12 through the pressure contrast channel 10 . The continuous phase liquid fed from the dyed continuous phase inlet 6 and the undyed continuous phase inlet 7 is the same liquid, the difference is that the dyed liquid flows in the channel of the dyed continuous phase inlet 6, so in the pressure comparison port A well-defined and stable interface can be formed at 11, and the interface will be displaced according to the pressure difference in the channels on both sides.

As shown in Figure 4(a), the pressure on both sides was adjusted before the droplet was generated so that the interface of the pressure comparison interface was in the middle, which was used as a benchmark for subsequent comparison experiments. Figure 4(b) shows the interface change diagram during the droplet formation process, and the interface is displaced downward at this time; Figure 4(c) shows the interface change diagram during the droplet movement, and the interface is displaced upward at this time. Through the comparison, we can clearly observe the corresponding relationship between the droplet flow position and the up-and-down displacement of the contrast interface interface during the generation and movement process.

Claims (2)

1. a kind of micro-fluidic chip measuring pressure change in the deformable channel of wall surface, it is characterised in that：Entire micro-fluidic chip It is made of cover plate (1), film layer (2) and substrate (3), three parts are made of PDMS material；Cover plate (1) is internally provided with microchannel Structure (4), microchannel structure (4) are equipped with open side；Film layer (2) is flat surface；Substrate (3) is internally provided with groove structure (5), it also is provided with open side on groove structure (5)；The open side in open side and groove structure (5) in microchannel structure (4) It is in direct contact cooperation with film layer (2), cover plate (1), film layer (2) and substrate (3) cooperatively form micro-fluidic chip successively up and down Overall structure；

The microchannel structure (4) includes drop formation part and pressure comparison part；

Drop formation part is by discrete phase entrance (8), undyed continuous phase entrance (7), outlet (12) and drop formation channel (9) it forms；Pressure comparison part is made of continuous phase entrance (6), pressure comparison channel (10) and the outlet (12) dyed；

The outlet (12) of drop formation part and the outlet (12) of pressure comparison part are the same mouths；Drop formation channel (9) Upstream be connected with discrete phase entrance (8) and undyed continuous phase entrance (7), the downstream and outlet of drop formation channel (9) (12) it communicates；The upstream in pressure comparison channel (10) is connected with the continuous phase entrance (6) of dyeing, under pressure comparison channel (10) Trip is also communicated with outlet (12)；Drop formation channel (9) and pressure comparison channel (10) pass through pressure in the downstream of drop formation Interface (11) is compared to connect；First alignment slot (13) is arranged in microchannel structure (4), and the second alignment slot (14) is arranged in groove In structure (5)；First alignment slot (13) is corresponding with the second alignment slot (14), to ensure cover plate (1), film layer (2) and base The bonding of piece (3) connects.

2. a kind of micro-fluidic chip measuring pressure change in the deformable channel of wall surface according to claim 1, feature It is：Since groove structure will be added in the main channel lower wall surface of drop formation in deformable lower wall surface microchannel, and it is smart by making Degree is limited, and the width of groove structure is more than the width of microchannel structure (4) main channel, complete in the width direction of main channel to be formed Thin-wall face structure, so the upstream of drop formation channel (9) and pressure comparison channel (10) will separate design to avoid mutual Interference, drop formation channel (9) and pressure comparison channel (10) are 90 ° of fold-line-shapeds；Due to pressure signal meeting in transmittance process Gradually decaying, so in order to measure the pressure change during drop formation, pressure comparison interface (11) is unable to chaotropic drop and crosses It is too far at generation.