Microfluidic sampling device and system
Through the combination of MEMS microfluidic chips and pressure control components, the problems of large size and integration of traditional gas chromatography injection devices have been solved, a miniaturized, low-cost and efficient injection device has been realized, and the separation efficiency and detection sensitivity of gas chromatography have been improved.
Patent Information
- Application Number
- CN202511021855.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-10-17
AI Technical Summary
Traditional gas chromatography injection devices have problems such as large size, dead volume interference, sample loss, flow path residue, poor high temperature adaptability, and difficulty in integration, which affect separation efficiency and detection sensitivity.
It uses MEMS microfluidic chips and pressure control components to achieve flow path switching by adjusting the air pressure difference, integrates a quantitative loop, reduces mechanical parts, uses corrosion-resistant materials, and integrates temperature-controlled thin film resistors, making it suitable for mass production.
It realizes a miniaturized injection valve, improves switching efficiency, reduces sample loss, reduces mechanical wear, and reduces costs. It is suitable for integration into portable GC equipment and improves separation efficiency and detection sensitivity.
Smart Images
Figure CN120801587A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of gas chromatography injection systems, and in particular to a microfluidic injection device. BACKGROUND
[0002] Gas chromatography (GC) is an analytical technique based on the difference in distribution between the stationary phase and the mobile phase (carrier gas) to realize separation. Its core process includes sample gasification, column separation and detector quantification, and the accuracy of the injection link directly affects the separation efficiency and detection sensitivity. The gas chromatography injection valve, as the core component of the chromatographic analysis system, its technical evolution has always been around the three core needs of quantitative accuracy, automation adaptability and complex sample compatibility. Traditional gas chromatography relies on mechanical injection devices such as six-way valves and syringes, but there are limitations such as large volume, dead volume interference, sample loss, flow path residue, poor high temperature adaptability, and difficulty in integration. SUMMARY
[0003] The present disclosure provides a microfluidic injection device and system to solve the technical problems recognized by the inventors. The injection device can be used for flow switching, and in a gas chromatography system, it can be applied as an injection valve.
[0004] The present disclosure provides a microfluidic injection device, comprising a MEMS microfluidic chip and a pressure control assembly; the MEMS microfluidic chip comprises: at least one injection channel, an outlet channel, and at least one evacuation channel; at least a first pneumatic control channel respectively communicating with the injection channel and the outlet channel, and a second pneumatic control channel communicating with the outlet channel at one end; wherein the injection channel and the outlet channel can be integrated with at least one dosing loop, and the dosing loop and the first pneumatic control channel are in parallel; the other end of the second pneumatic control channel is connected with a detection unit; The pressure control assembly is configured to: in response to different modes, by adjusting the gas pressure difference between the first pneumatic control channel, the second pneumatic control channel, and the injection channel and / or the outlet channel, to control the different flow directions of the sample through the dosing loop.
[0005] Preferably, the MEMS microfluidic chip further comprises a first gas flow inlet, a second gas flow inlet, a third gas flow inlet, a first gas flow outlet, a second gas flow outlet, an injection port, a first evacuation channel, and a second evacuation channel; Wherein, one end of the injection channel is connected to the first air flow inlet, and the other end is connected to the input end of the quantitative loop; one end of the first exhaust channel is connected to the injection channel, and the other end is connected to the first air flow outlet; one end of the second exhaust channel is connected to the second air flow outlet, and the other end is connected to the output end of the quantitative loop; one end of the first gas control channel is connected to the second air flow inlet, and the other end is respectively connected to the injection channel and the second exhaust channel; one end of the second gas control channel is connected to the third air flow inlet, and the other end is connected to the injection port, and the injection port is connected to the detection unit; One end of the pressure control component can be connected to an external carrier gas input pipeline, and the other end is connected to the second air flow inlet and the third air flow inlet respectively.
[0006] Preferably, the pressure control component includes a first pressure controller and a second pressure controller, the input ends of the first pressure controller and the second pressure controller can be connected to external carrier gas input pipelines respectively, the output end of the first pressure controller is connected to the second air flow inlet, and the output end of the second pressure controller is connected to the third air flow inlet.
[0007] Preferably, the injection channel is divided into a first section and a second section at the connection point of the first gas control channel; In the first mode, the pressure control component controls the pressure of the first gas control channel to be lower than the pressure of the first section, so that the sample collected in the first section enters the quantitative loop through the second section.
[0008] Preferably, the sample outlet channel is divided into a third section and a fourth section at the connection point with the second gas control channel, and the fourth section is connected to the second exhaust channel; In the first mode, the pressure in the second gas control channel is controlled to be greater than that in the third section. At this time, the sample in the third section passes through the fourth section and is discharged through the second exhaust channel.
[0009] Preferably, the second gas control channel is divided into a fifth section and a sixth section at the connection with the sample outlet channel, and the sixth section is connected to the sample inlet; In the second mode, the pressure control component controls the pressure of the first air control channel to be greater than the pressure of the first section, and the pressure of the second air control channel to be less than the pressure of the third section; So that the gas in the first section flows in the reverse direction into the first exhaust channel; the auxiliary gas in the fifth section passes through the fourth section and the second section and purges the sample in the quantitative loop into the third section, and then the sample passes through the sixth section from the injection port to the detection unit.
[0010] Preferably, in the second mode, the pressure of the second air control channel is adjusted to a first value; After the pressure of the second pneumatic control channel is maintained at the first value for a first time length, the pressure of the second pneumatic control channel is switched from the first value to a second value; The first value is greater than the pressure of the third section, and the second value is less than the pressure of the third section, and after the pressure of the second pneumatic control channel is switched to the second value, the sample in the quantitative ring is switched to be discharged from the second evacuation channel.
[0011] Preferably, an S-shaped sample storage channel is arranged in the quantitative ring; and / or The volume of the sample storage channel ranges from 1 nL to 100 nL.
[0012] Preferably, a thin film resistor for temperature control is arranged on the surface of the MEMS microfluidic chip. The sample inlet channel, the first evacuation channel, the second evacuation channel, the first pneumatic control channel and the second pneumatic control channel are made of corrosion-resistant materials.
[0013] The present application provides a microfluidic sampling system, which comprises the above-mentioned microfluidic sampling device and a standard gas bottle and a carrier gas bottle.
[0014] The beneficial effects of the present disclosure mainly include: 1. The present application can improve the switching efficiency by regulating the air pressure through the pressure control assembly to realize the rapid switching of the air path.
[0015] 2. The size of the valve body of the present application is reduced from centimeter level to micron level, which can be integrated with other chromatography chips, reduce the connection between elements, and be integrated into a portable GC device.
[0016] 3. The quantitative ring can be integrated in the MEMS microfluidic chip of the present application, and the volume of the quantitative ring can be as low as nanoliter level, thereby saving precious samples (such as biological fluids and trace pollutants).
[0017] 4. The air flow channel of the MEMS microfluidic chip of the present application is mostly made of corrosion-resistant materials such as silicon and glass, which can reduce the adsorption and corrosion of the sample. 5. The chip structure of the present application has no moving parts (such as microvalves driven by thermal expansion or electrostatic force), which reduces the risk of mechanical wear and tear and reduces 90% of the assembly steps. 6. The thin film resistor on the surface of the chip is prepared by microfabrication technology, which is used for temperature control and can greatly reduce power consumption. 7. The microfabrication technology (photolithography, etching) of the present application is suitable for mass production, and the unit cost is significantly lower than that of traditional mechanical valve bodies, thereby reducing material consumption (such as the amount of precious metals).
[0018] It is to be understood that both the foregoing general description and the following detailed description are merely intended to illustrate and explain the subject disclosure. The accompanying drawings are included to provide a further understanding of the subject disclosure and are incorporated in and constitute a part of the specification. Meanwhile, the specification and drawings are used to explain the principles of the subject disclosure. BRIEF DESCRIPTION OF DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the specific embodiments of the present disclosure or the prior art, the drawings required to be used in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art without creative labor.
[0020] Figure 1 Structure schematic diagram of microfluidic sampling device of the embodiment of the present disclosure; Figure 2 Gas flow schematic diagram of system sampling process of the embodiment of the present disclosure; Figure 3 Gas flow schematic diagram of system sampling process of the embodiment of the present disclosure; Figure: 100-MEMS microfluidic chip; 101-first air inlet; 102-second air inlet; 103-third air inlet; 104-first air outlet; 105-second air outlet; 106-sampling port; 107-sampling channel; 107a-first section; 107b-second section; 108-first emptying channel; 109-second emptying channel; 110-first gas control channel; 111-second gas control channel; 111a-fifth section; 111b-sixth section; 112-carrier gas input pipeline; 113-sampling channel; 113a-third section; 113b-fourth section; 200-quantitative ring; 201-sample storage channel; 301-first pressure controller; 302-second pressure controller; 400-standard gas bottle; 500-carrier gas bottle. DETAILED DESCRIPTION
[0021] The technical solutions of the present disclosure will be described below in conjunction with the drawings, obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments.
[0022] Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present disclosure.
[0023] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this disclosure and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0024] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on the specific circumstances.
[0025] Example like Figure 1 As shown, this embodiment provides a microfluidic sampling device, including a MEMS microfluidic chip 100 and a pressure control component; the MEMS microfluidic chip 100 includes: At least one sample inlet channel 107, a sample outlet channel 113 and at least one exhaust channel; A first gas control channel 110 connected to at least the sample inlet channel 107 and the sample outlet channel 113, and a second gas control channel 111 connected to the sample outlet channel 113 at one end; Among them, at least a certain amount of ring 200 can be integrated between the sample inlet channel 107 and the sample outlet channel 113, and the quantitative ring 200 and the first gas control channel 110 are connected in parallel; the other end of the second gas control channel 111 is connected to the detection unit; The pressure control component is configured to: in response to different modes, control the sample to form different flow directions through the quantitative ring 200 by adjusting the pressure difference between the first gas control channel 110, the second gas control channel 111, and the injection channel 107 and / or the sample outlet channel 113.
[0026] Specifically, the MEMS microfluidic chip 100 further includes a first air flow inlet 101, a second air flow inlet 102, a third air flow inlet 103, a first air flow outlet 104, a second air flow outlet 105, an injection port 106, a first exhaust channel 108, and a second exhaust channel 109; The sample injection channel 107 is connected at one end with the first gas flow inlet 101 and at the other end with the input end of the dosing ring 200. The first emptying channel 108 is connected at one end with the sample injection channel 107 and at the other end with the first gas flow outlet 104. The second emptying channel 109 is connected at one end with the second gas flow outlet 105 and at the other end with the output end of the dosing ring 200. The first gas control channel 110 is connected at one end with the second gas flow inlet 102 and at the other end with the sample injection channel 107 and the second emptying channel 109, respectively. The second gas control channel 111 is connected at one end with the third gas flow inlet 103 and at the other end with the sample injection port 106, which is in communication with the detection unit. The pressure control assembly is connected at one end with the carrier gas input pipeline 112 and at the other end with the second gas flow inlet 102 and the third gas flow inlet 103, respectively.
[0027] Specifically, the pressure control assembly comprises a first pressure controller 301 and a second pressure controller 302. The input ends of the first pressure controller 301 and the second pressure controller 302 are respectively connected with the carrier gas input pipeline 112. The output end of the first pressure controller 301 is connected with the second gas flow inlet 102, and the output end of the second pressure controller 302 is connected with the third gas flow inlet 103.
[0028] Specifically, the sample injection channel 107 is divided into a first section 107a and a second section 107b at the connection of the first gas control channel 110. In the first mode, the pressure control assembly controls the pressure of the first gas control channel 110 to be less than the pressure of the first section 107a, so that the sample collected in the first section 107a enters the dosing ring 200 through the second section 107b.
[0029] Specifically, the sample outlet channel 113 is divided into a third section 113a and a fourth section 113b at the connection of the second gas control channel 111. The fourth section 113b is in communication with the second emptying channel 109. In the first mode, the pressure in the second gas control channel 111 is controlled to be greater than the pressure in the third section 113a. At this time, the sample in the third section 113a is discharged through the fourth section 113b and the second emptying channel 109.
[0030] Specifically, the second gas control channel 111 is divided into a fifth section 111a and a sixth section 111b at the connection with the sample outlet channel 113. The sixth section 111b is connected with the sample injection port 106. In the second mode, the pressure control assembly controls the pressure of the first gas control channel 110 to be greater than the pressure of the first section 107a, and the pressure of the second gas control channel 111 to be greater than the pressure of the third section 113a. so that the gas in the first section 107a flows reversely into the first evacuation channel 108; after the auxiliary gas in the fifth section 111a flows into the third section 113a through the fourth section 113b, the second section 107b and purges the sample in the dosing ring 200, the sample flows from the sample inlet 106 to the detection unit through the sixth section 111b.
[0031] Specifically, in the second mode, the pressure of the second gas control channel 111 is regulated to a first value; After the pressure of the second gas control channel 111 is maintained at the first value for a preset first time length, the pressure of the second gas control channel 111 is switched from the first value to a second value; wherein the first value is greater than the pressure of the third section 113a, and the second value is less than the pressure of the third section 113a, and after the pressure of the second gas control channel 111 is switched to the second value, the sample in the dosing ring 200 is switched to be discharged from the second evacuation channel 109.
[0032] In the embodiment, the sample inlet device includes a first mode and a second mode, wherein the first mode is a sampling mode, and the second mode is a sample inlet mode: Sampling mode: as shown in Figure 2 the solid line in the figure is the flow direction of the marker gas, and the dotted line is the flow direction of the carrier gas, the first pressure controller 301 is adjusted so that the pressure of the first gas control channel 110 is less than the pressure of the first section 107a in the sample inlet channel 107, and the second pressure controller 302 is adjusted so that the pressure of the fifth section 111a in the second gas control channel 111 is greater than the pressure of the third section 113a in the sample outlet channel 113; then the marker gas is input through the marker gas bottle 400, the marker gas in the marker gas bottle 400 enters the sample inlet channel 107 through the first gas flow inlet 101, part of which enters the dosing ring 200 through the sample inlet channel 107, and part of which is evacuated through the first evacuation channel 108; the sample passing through the dosing ring 200 flows to the second evacuation channel 109, and then is discharged from the second gas flow outlet 105 for evacuation.
[0033] Sample inlet process: as shown in Figure 3As shown, the solid line in the figure is the direction of the standard gas flow, and the dashed line is the direction of the carrier gas flow. The sampling process lasts for a period of time, so that the standard gas in the quantitative ring 200 is filled, the first pressure controller 301 is adjusted, the pressure of the first gas control channel 110 is greater than the pressure of the first section 107a in the sample channel 107, the second pressure controller 302 is adjusted, the pressure of the second gas control channel 111 is greater than the pressure of the third section 113a, at this time, the gas in the first section 107a of the sample channel 107 flows reversely into the first evacuation channel 108 for evacuation, the gas in the second gas control channel 111 passes through the fifth section 111a, the fourth section 113b, the first gas control channel 110, enters the quantitative ring 200 from the second section 107b of the sample channel 107, and sweeps the standard gas in the quantitative ring 200 out, enters the third section 113a of the sample outlet channel 113, and due to the relatively large pressure of the fifth section 111a of the second gas control channel 111, the gas passing through the third section 113a enters the chromatographic column and the detector from the second gas control channel 111 through the sixth section 111b from the sample inlet 106, and after a certain period of time, the sampling process is completed.
[0034] Further, in the second mode, the pressure of the second gas control channel 111 is adjusted to a first value; After the pressure of the second gas control channel 111 is maintained at the first value for a preset first time length, the pressure of the second gas control channel 111 is switched from the first value to a second value; Wherein, the first value is greater than the pressure of the third section 113a, and the second value is less than the pressure of the third section 113a, when the pressure of the second gas control channel 111 is switched to the second value, the sample in the quantitative ring 200 is switched to be discharged from the second evacuation channel 109.
[0035] In this embodiment, by presetting a first time length, the pressure value is automatically switched to achieve the purpose of automatic control.
[0036] Further, the quantitative ring 200 is provided with an "S" shaped sample storage channel 201. The "S" shaped sample storage channel 201 is arranged in the quantitative ring 200, which can increase the storage amount of gas under the condition of small volume.
[0037] Further, the volume of the sample storage channel 201 can be processed to the order of nL. In this embodiment, the volume of the sample storage channel 201 is 1-100 nL, which can be produced according to the demand, and the storage range of the quantitative ring 200 is as low as nanoliter level, which saves precious samples (such as biological fluids, trace pollutants), and avoids waste.
[0038] Further, the surface of the MEMS microfluidic chip 100 is provided with a thin film resistance for temperature control. The thin film resistance is prepared on the surface of the chip by microprocessing technology, which is used for temperature control and can greatly reduce power consumption.
[0039] Further, the sample injection channel 107, the first emptying channel 108, the second emptying channel 109, the first gas control channel 110 and the second gas control channel 111 are made of corrosion-resistant materials. In the embodiment, the corrosion-resistant materials can be silicon, glass, etc., which can reduce the adsorption and corrosion of the sample.
[0040] A microfluidic sample injection system, comprising the microfluidic sample injection device and a standard gas bottle 400 and a carrier gas bottle 500, the standard gas bottle 400 being connected to the first gas flow inlet 101, and the carrier gas bottle being connected to the carrier gas input pipeline 112.
[0041] The working principle of the system is as follows: in the system, the microfluidic sample injection system comprises a microfluidic sample injection device, a standard gas bottle 400 and a carrier gas bottle 500; the working process includes a first mode and a second mode, wherein the first mode is a sampling mode, and the second mode is a sample injection mode. Sampling mode: as shown in Figure 2 The solid line in the figure is the flow direction of the standard gas, and the dashed line is the flow direction of the carrier gas. The first pressure controller 301 is adjusted so that the pressure in the first gas control channel 110 is less than the pressure in the first section 107a of the sample injection channel 107. The second pressure controller 302 is adjusted so that the pressure in the fifth section 111a of the second gas control channel 111 is greater than the pressure in the third section 113a of the sample outlet channel 113. The sixth section 111b has a flow rate, which can flow into the carrier gas of the chromatographic column. Then, the standard gas is input through the standard gas bottle 400. The standard gas in the standard gas bottle 400 enters the sample injection channel 107 through the first gas flow inlet 101. Part of the standard gas enters the quantitative ring 200 through the sample injection channel 107, and part of the standard gas is emptied through the first emptying channel 108. The sample passing through the quantitative ring 200 flows to the second emptying channel 109, and then is discharged from the second gas flow outlet 105 for emptying.
[0042] Sample injection process: as shown in Figure 3As shown, the solid line in the figure is the direction of the standard gas flow, and the dotted line is the direction of the carrier gas flow. After the sampling process lasts for a period of time, the first pressure controller 301 is adjusted so that the pressure of the first gas control channel 110 is greater than the pressure of the first section 107a in the sampling channel 107; the second pressure controller 302 is adjusted so that the pressure of the second gas control channel 111 is greater than the pressure of the third section 113a; at this time, the gas in the first section 107a of the sampling channel 107 flows reversely into the first evacuation channel 108 for evacuation; the gas in the second gas control channel 111 passes through the fifth section 111a, the fourth section 113b, the first gas control channel 110, and then enters the second section 107b of the sampling channel 107 to blow out the standard gas in the loop 200, and enters the third section 113a of the outlet channel 113; at this time, the carrier gas in the sixth section 113b also flows to the fourth section 113a; due to the relatively large pressure of the fifth section 111a of the second gas control channel 111, the gas passing through the third section 113a enters the sampling port 106 from the sixth section 111b of the second gas control channel 111, enters the chromatographic column and the detector, and completes the sampling process after a certain period of time.
[0043] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present disclosure, and not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present disclosure.
Claims
1. A microfluidic sampling device, characterized in that: It includes a MEMS microfluidic chip and a pressure control component; the MEMS microfluidic chip includes: At least one sample inlet channel, a sample outlet channel and at least one emptying channel; a first gas control channel connected at least to the sample inlet channel and the sample outlet channel, and a second gas control channel connected at one end to the sample outlet channel; Among them, at least a certain amount of loop can be integrated between the sample inlet channel and the sample outlet channel, and the quantitative loop and the first gas control channel are connected in parallel; the other end of the second gas control channel is connected to the detection unit; The pressure control component is configured to: in response to different modes, control the sample to form different flow directions through the quantitative loop by adjusting the pressure difference between the first gas control channel, the second gas control channel, and the injection channel and / or the sample output channel.
2. A microfluidic sampling device according to claim 1, characterized in that: The MEMS microfluidic chip further includes a first air flow inlet, a second air flow inlet, a third air flow inlet, a first air flow outlet, a second air flow outlet, an injection port, a first exhaust channel, and a second exhaust channel; Wherein, one end of the injection channel is connected to the first air flow inlet, and the other end is connected to the input end of the quantitative loop; one end of the first exhaust channel is connected to the injection channel, and the other end is connected to the first air flow outlet; one end of the second exhaust channel is connected to the second air flow outlet, and the other end is connected to the output end of the quantitative loop; one end of the first gas control channel is connected to the second air flow inlet, and the other end is respectively connected to the injection channel and the second exhaust channel; one end of the second gas control channel is connected to the third air flow inlet, and the other end is connected to the injection port, and the injection port is connected to the detection unit; One end of the pressure control component can be connected to an external carrier gas input pipeline, and the other end is connected to the second air flow inlet and the third air flow inlet respectively.
3. A microfluidic sampling device according to claim 2, characterized in that: The pressure control component includes a first pressure controller and a second pressure controller, the input ends of the first pressure controller and the second pressure controller can be connected to external carrier gas input pipelines respectively, the output end of the first pressure controller is connected to the second air flow inlet, and the output end of the second pressure controller is connected to the third air flow inlet.
4. A microfluidic sampling device according to claim 2, characterized in that: The injection channel is divided into a first section and a second section at the connection point of the first gas control channel; In the first mode, the pressure control component controls the pressure of the first gas control channel to be lower than the pressure of the first section, so that the sample collected in the first section enters the quantitative loop through the second section.
5. A microfluidic sampling device according to claim 4, characterized in that: The sample outlet channel is divided into a third section and a fourth section at the connection with the second gas control channel, and the fourth section is connected to the second exhaust channel; In the first mode, the pressure in the second gas control channel is controlled to be greater than that in the third section. At this time, the sample in the third section passes through the fourth section and is discharged through the second exhaust channel.
6. A microfluidic sampling device according to claim 5, characterized in that: The second gas control channel is divided into a fifth section and a sixth section at the connection with the sample outlet channel, and the sixth section is connected to the sample inlet; In the second mode, the pressure control component controls the pressure of the first air control channel to be greater than the pressure of the first section, and the pressure of the second air control channel to be less than the pressure of the third section; so that the gas in the first section flows in the reverse direction into the first exhaust channel; The auxiliary gas of the fifth section passes through the fourth section and the second section and purges the sample in the quantitative loop into the third section. The sample then passes through the sixth section from the injection port to the detection unit.
7. A microfluidic sampling device according to claim 6, characterized in that: In the second mode, the pressure of the second air control channel is adjusted to a first value; After the pressure of the second air control channel maintains the first value for a preset first time period, controlling the pressure of the second air control channel to switch from the first value to a second value; The first value is greater than the pressure of the third section, and the second value is less than the pressure of the third section. When the pressure of the second gas control channel is switched to the second value, the sample in the quantitative loop is switched to be discharged from the second exhaust channel.
8. The microfluidic sampling device according to any one of claims 1 to 7, characterized in that: An S-shaped sample storage channel is provided in the quantitative ring; and / or The volume range of the sample storage channel is 1-100nL.
9. The microfluidic sampling device according to claim 8, characterized in that: The surface of the MEMS microfluidic chip is provided with a thin film resistor for temperature control; The injection channel, the first exhaust channel, the second exhaust channel, the first gas control channel and the second gas control channel are made of corrosion-resistant materials.
10. A microfluidic injection system, characterized in that: A microfluidic sampling device comprising any one of claims 1 to 9; And a standard gas bottle and a carrier gas bottle, wherein the standard gas bottle is connected to the first air flow inlet, and the carrier gas bottle is connected to the carrier gas input pipeline.