Micro chip type pre-concentration device based on MEMS technology

Abstract

The invention discloses a miniaturized chip type pre-concentration device based on an MEMS (Micro Electro Mechanical System) technology. The device comprises a chip type concentration module, a mass flow meter, a six-way switching valve and a vacuum pump, a first connecting port of the six-way switching valve is communicated with a carrier gas source, a third connecting port and a sixth connecting port of the six-way switching valve are respectively communicated with two ends of the chip type concentration module, and a fifth connecting port of the six-way switching valve is communicated with an inlet of the mass flow meter; a second connecting port of the six-way switching valve is communicated with an analytical instrument, and a fourth connecting port of the six-way switching valve is communicated with a sample gas outlet pipeline; and an outlet of the mass flow meter is connected with the vacuum pump. According to the invention, a micro electro mechanical system technology is introduced, and the chip type concentration module obtained by preparing an integrated chip type trapping and desorption structure through a silicon-based etching process replaces a traditional tubular trapping and desorption structure, so that the volume of a sample introduction system is reduced, the thermal capacity is reduced, and the thermal response speed is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of detection analysis technology, and particularly relates to a miniaturized chip type pre-concentration device based on MEMS technology. BACKGROUND

[0002] The pre-concentration instrument is a core equipment for improving the detection sensitivity of trace gases in the field of detection analysis. Its working principle is as follows: under low temperature conditions, a specific adsorption material is used to capture trace gases, and then the gases are focused and sent into an analysis instrument (such as a gas chromatograph or a gas mass spectrometer) for detection through rapid heating desorption. This reduces the detection limit of the analysis instrument and improves the measurement accuracy. At present, the traditional pre-concentration technology usually adopts a tubular capture cold trap structure, which has the following disadvantages:

[0003] Volume and heat capacity problems: the volume of the traditional tubular capture cold trap structure is usually (1-5) mL, and the heat capacity is large, which leads to a slow response of heat transfer and makes it difficult to quickly reach the target temperature. During the sampling process after capture, the sample cannot be quickly desorbed, and diffusion is easy to occur, which directly reduces the measurement accuracy of the analysis instrument.

[0004] Spectrum broadening and power consumption problems: the dead volume of the tubular structure is usually large, which easily leads to a too wide peak of the sample spectrum, affecting the separation effect; at the same time, a large volume structure requires higher power consumption, which limits the portability and energy efficiency of the equipment.

[0005] Refrigeration temperature limitation: the existing semiconductor refrigeration technology uses semiconductor refrigeration sheets, and the internal temperature limit of the tube type can only reach-40℃ to-50℃, which is difficult to meet the high-efficiency capture demand of low-boiling-point trace components, and the concentration efficiency is limited.

[0006] Therefore, there is an urgent need for a miniaturized chip type pre-concentration device based on MEMS technology. SUMMARY

[0007] In view of the above problems, the present application is proposed to provide a miniaturized chip type pre-concentration device based on MEMS technology which overcomes the above problems or at least partially solves the above problems.

[0008] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0009] The embodiment of the present application provides a miniaturized chip type pre-concentration device based on MEMS technology, which comprises a chip type concentration module, a mass flow meter, a six-way switching valve and a vacuum pump; the six-way switching valve comprises six connection ports, wherein the first connection port of the six-way switching valve is connected with a carrier gas source, the third connection port and the sixth connection port of the six-way switching valve are respectively connected with two ends of the chip type concentration module, the fifth connection port of the six-way switching valve is connected with the inlet of the mass flow meter, the second connection port of the six-way switching valve is connected with an analytical instrument, and the fourth connection port of the six-way switching valve is connected with a sample gas outlet pipeline; the outlet of the mass flow meter is connected with the vacuum pump.

[0010] In some embodiments of the present application, the miniaturized chip type pre-concentration device based on MEMS technology further comprises a cabinet integrated with a control system and a power supply module, the chip type concentration module, the mass flow meter, the six-way switching valve and the vacuum pump are arranged in the cabinet, the chip type concentration module, the mass flow meter, the six-way switching valve and the vacuum pump are electrically connected with the control system, and the chip type concentration module, the mass flow meter, the six-way switching valve, the vacuum pump and the control system are electrically connected with the power supply module.

[0011] In some embodiments of the present application, the chip type concentration module comprises a micro etching chip, a filling layer, a temperature control unit and a temperature measuring unit; the micro etching chip is provided with the filling layer, the temperature control unit is embedded on the micro etching chip or arranged on the upper surface or the lower surface of the micro etching chip, and the temperature measuring unit is packaged in the inner groove of the micro etching chip.

[0012] In some embodiments of the present application, the filling layer is composed of an adsorbent material and a metal grid network.

[0013] In some embodiments of the present application, the micro etching chip comprises a base, an inner cavity and a cover plate, the base is made of silicon, the base is bonded and sealed with the cover plate, and the sealed inner cavity is formed.

[0014] In some embodiments of the present application, the micro etching chip further comprises a microfluidic dam and a micro column array, the inner cavity is provided with the micro column array, the micro column array is covered with the filling layer, and the outer side of the micro column array is provided with the microfluidic dam.

[0015] In some embodiments of the present application, the cover plate is provided with a filler injection port communicated with the inner cavity in the region corresponding to the micro column array.

[0016] In some embodiments of the present application, the outer side region of the cover plate corresponding to the microfluidic dam is respectively provided with an air inlet and an air outlet which are in communication with the inner cavity.

[0017] In some embodiments of the present application, the air inlet and the air outlet are respectively provided with airflow transmission lines, and the airflow transmission lines are capillary air tubes.

[0018] In some embodiments of the present application, the inner cavity of the micro-etching chip is provided with a plurality of accommodating grooves outside the inner cavity, and the temperature measuring unit is arranged in the accommodating grooves.

[0019] The technical scheme provided in the embodiments of the present application has at least the following technical effects or advantages:

[0020] The miniaturized chip type pre-concentration device based on the MEMS technology has the chip type concentration module for the concentration structure, the chip type structure solves the problem of large dead volume of the pipe type trapping and desorption, reduces the influence of the sample components vertically diffused after thermal analysis, improves the sample amount accuracy, especially for low boiling point components, reduces the sample component peak spread rate by more than 10% through reducing the dead volume and rapid thermal desorption, realizes effective switching of the gas circuit through the six-way switching valve, further reduces the space occupation compared with the complex pipeline, and introduces the micro-electro-mechanical system (MEMS) technology, so that the chip type concentration module is obtained through the silicon-based etching process to replace the traditional pipe type trapping and desorption structure, realizes the volume reduction of the sample system, and reduces the heat capacity to 1 / 40 of the traditional pipe type, and significantly improves the thermal response speed.

[0021] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0023] Figure 1 A schematic diagram of the principle structure of a miniaturized chip type pre-concentration device based on the MEMS technology is provided in the embodiments of the present application.

[0024] Figure 2 A structural schematic diagram of the chip type concentration module is provided.

[0025] Figure 3 is a top view of a micro-etching chip;

[0026] Figure 4 is an axonometric view of a micro-etching chip;

[0027] Figure 5 is a schematic view of the connection of a six-way switching valve in the adsorption trapping stage;

[0028] Figure 6 is a schematic view of the connection of a six-way switching valve in the desorption sampling stage;

[0029] Figure 7 is a temperature change curve in the continuous three-time test of the chip-type concentration module;

[0030] Figures 8-14 are component calibration curves of hydrogen sulfide, carbonyl sulfide, ethyl mercaptan, dimethyl sulfide, carbon disulfide, thiophene, and dimethyl disulfide, respectively;

[0031] Figure 15 is a typical chromatogram of 10 mL of a 10 nmol / mol sulfur compound gas standard material concentrated on a gas chromatograph;

[0032] Figure 16 is a typical chromatogram of 800 mL of a 10 nmol / mol sulfur compound gas standard material concentrated on a gas chromatograph.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 1, first connection port; 2, second connection port; 3, third connection port; 4, fourth connection port; 5, fifth connection port; 6, sixth connection port;

[0035] 10, chip-type concentration module; 11, micro-etching chip; 12, filling layer; 13, temperature control unit; 14, temperature measurement unit; 111, base; 112, inner cavity; 113, microfluidic dam; 114, microcolumn array; 115, accommodation groove; 150, cover plate; 151, filler injection port; 152, gas inlet; 153, gas outlet;

[0036] 20, mass flow meter;

[0037] 30, six-way switching valve;

[0038] 40, vacuum pump;

[0039] 50, carrier gas source;

[0040] 60, analysis instrument. DETAILED DESCRIPTION

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0042] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0043] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0044] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0045] Figure 1 A schematic diagram of the principle structure of a miniaturized chip-type pre-concentration device based on MEMS technology is provided for an embodiment of the present invention, as shown below. Figure 1 As shown, the miniaturized chip-based pre-concentration device based on MEMS technology includes: a chip-based concentration module 10, a mass flow meter 20, a six-way switching valve 30, and a vacuum pump 40. The six-way switching valve 30 includes six connection ports. The first connection port 1 of the six-way switching valve 30 is connected to a carrier gas source 50. The third connection port 3 and the sixth connection port 6 of the six-way switching valve 30 are respectively connected to the two ends of the chip-based concentration module 10. The fifth connection port 5 of the six-way switching valve 30 is connected to the inlet of the mass flow meter 20. The second connection port 2 of the six-way switching valve 30 is connected to an analytical instrument 60. The fourth connection port 4 of the six-way switching valve 30 is connected to a sample gas outlet pipeline. The outlet of the mass flow meter 20 is connected to the vacuum pump 40.

[0046] In the embodiment of the present application, the chip-type concentration module 10 is used to trap and inject target components; the six-way switching valve 30 is used to switch the gas path state (concentration / injection / cleaning) by changing the connection path, to realize the switching of the passage of sample gas, carrier gas and the analysis instrument 60; the mass flow meter 20 (MFC) is used to accurately control the flow of sample gas and carrier gas (range 1-100 mL / min); the vacuum pump 40 is used to provide a negative pressure environment to assist the introduction of sample gas into the chip-type concentration module 10; the carrier gas source 50 is used to provide carrier gas, which is the gas of the mobile phase, and the main function is to transport sample gas; the analysis instrument 60, for example, a gas chromatograph, is used for data analysis of gas.

[0047] In other embodiments of the present application, the miniaturized chip-type pre-concentration device based on MEMS technology can further include a case integrated with a control system (including a PID controller) and a power supply module, the chip-type concentration module 10, the mass flow meter 20, the six-way switching valve 30 and the vacuum pump 40 are all arranged in the case, the chip-type concentration module 10, the mass flow meter 20, the six-way switching valve 30 and the vacuum pump 40 are all electrically connected with the control system, the chip-type concentration module 10, the mass flow meter 20, the six-way switching valve 30, the vacuum pump 40 and the control system are all electrically connected with the power supply module, the control system is a conventional control module, which is used to provide accurate control and linkage for the connected active devices, the power supply module is used to provide power support for the connected active devices, and the case provides physical support and protection for the components installed therein.

[0048] In combination with Figures 2-4 as shown, Figure 2 the structural schematic diagram of the chip-type concentration module 10, Figure 3 the top view of the micro-etching chip 11, Figure 4It is an axonometric view of the micro-etching chip 11. The chip-type concentration module 10 comprises a micro-etching chip 11, a filling layer 12, a temperature control unit 13 and a temperature measuring unit 14. The filling layer 12 is arranged in the micro-etching chip 11. The temperature control unit 13 is embedded in the micro-etching chip 11, or arranged on the upper or lower surface of the micro-etching chip 11. The temperature measuring unit 14 is encapsulated in the micro-etching chip 11. The temperature control unit 13 is used to adjust the temperature of the micro-etching chip 11, including heating and refrigeration. The temperature control unit 13 is realized by a heating unit when heating. The heating unit is a micro-patterning metal film (silver, chromium / nickel or titanium / platinum) embedded in the micro-etching chip 11, or arranged on the upper or lower surface of the micro-etching chip 11. The PID controller of the control system is used to realize rapid heating. The target temperature is, for example, 80-150℃. The temperature control unit 13 is realized by a refrigeration unit when refrigerating. The refrigeration unit is a multi-stage semiconductor refrigeration sheet stack structure (2-3 stages) embedded in the micro-etching chip 11, or arranged on the upper or lower surface of the micro-etching chip 11. The control system is used to realize deep refrigeration. The temperature measuring unit 14 is used to monitor the temperature of the micro-etching chip 11 in real time, and feedback to the PID controller of the control system to realize closed-loop control.

[0049] The filling layer 12 is composed of, for example, adsorbent material and metal grid network. The adsorbent material is used to selectively capture target components. The material can be selected according to the application requirements (such as activated carbon, molecular sieve, polymer, etc.). The metal grid network is used to avoid the loss of filling material.

[0050] The micro-etching chip 11 comprises a base 111, an inner cavity 112, a microfluidic dam 113, a micro-column array 114 and a cover plate 150; the base 111 is made of silicon, the base 111 is bonded and sealed with the cover plate 150, and the inner cavity 112 is formed, the inner cavity 112 is patterned on the silicon base 111 by MEMS silicon-based etching process, and mass production is realized; the size of a single chip unit of the micro-etching chip 11 is 24.90mm*8.30mm, and the volume of the inner cavity 112 is 49μL (only 1 / 20-1 / 100 of the volume of a traditional cold trap); the micro-column array 114 is arranged in the inner cavity 112, and the filling layer 12 is arranged on the micro-column array 114; the outer side of the micro-column array 114 is provided with the microfluidic dam 113, the microfluidic dam 113 is formed by etching a column, which can prevent the filling layer 12 from being blown out by airflow and block particles from entering the cavity, thereby ensuring the stability of the filling material; the cover plate 150 is provided with a filling material injection port 151 corresponding to the region of the micro-column array 114 and communicating with the inner cavity 112, so as to provide an injection position for the filling layer 12; the outer side region of the cover plate 150 corresponding to the microfluidic dam 113 is respectively provided with an air inlet 152 and an air outlet 153 which communicate with the inner cavity 112, external sample gas is introduced into the inner cavity 112 through the air inlet 152 and enters the micro-column array 114, and then is discharged from the inner cavity 112 through the air outlet 153; the air inlet 152 and the air outlet 153 are respectively provided with airflow transmission lines, and the airflow transmission lines adopt, but are not limited to, capillary air pipes (such as inert metal pipes or air quartz capillary chromatographic columns) to transmit airflow.

[0051] In the embodiment of the present application, the adsorbent material of the filling layer 12 can be sucked into the inner cavity 112 from the injection port by forming negative pressure in the air inlet 152 or the air outlet 153 of the inner cavity 112 through the vacuum pump 40; or the adsorbent monomer solution is injected and coated in the inner cavity 112 by in-situ synthesis, and then polymerization or reaction is carried out under certain conditions, such as ultraviolet polymerization, to form a three-dimensional porous structure.

[0052] The inner cavity 112 of the micro-etching chip 11 is provided with a plurality of accommodation grooves 115, and the temperature measuring unit 14 is arranged in the accommodation grooves 115 to measure and obtain temperature data in the inner cavity 112.

[0053] In the embodiment of the present application, the chip-type concentration module 10 is used in combination with the analysis instrument 60, and the working process comprises five stages of flow setting, cleaning and pre-saturation, adsorption capture, desorption sampling and repeated operation.

[0054] During the process setup stage, this embodiment of the invention connects the second connection port 2 of the six-way switching valve 30 to the analytical instrument 60, and electrically connects the control system to the analytical instrument 60 via a communication interface to ensure unobstructed gas path and stable signal; the control system sets basic parameters such as process (i.e., pre-concentration method), injection sequence (1 to 999 times), and injection cycle (1 to 999 min).

[0055] The cleaning and pre-saturation stages include cleaning the gas path and pre-saturation. During the cleaning operation, in this embodiment, high-purity gas (such as nitrogen or zero-grade air) is introduced through the sample gas inlet via the fourth connection port 4 of the six-way switching valve 30. Based on the set number of cleaning cycles (1 to 999 times), residual sample gas from the previous cycle is removed from the system. During the pre-saturation operation, the sample gas to be tested is introduced through the fourth connection port 4 of the six-way switching valve 30. Based on the set number of pre-saturation cycles (1 to 999 times), the gas path system is pre-saturated to avoid adsorption deviations during subsequent concentration processes.

[0056] During the adsorption and capture stage, see [reference needed]. Figure 5 As shown, Figure 5 The diagram shows the connection of the six-way switching valve 30 during the adsorption and capture stage. When the six-way switching valve 30 is switched to the concentration state, the internal pipelines of the first connection port 1 and the second connection port 2 of the six-way switching valve 30 are connected, the internal pipelines of the fifth connection port 5 and the sixth connection port 6 are connected, and the internal pipelines of the third connection port 3 and the fourth connection port 4 are connected. The cooling unit is started, and the temperature is lowered to the target temperature (-20 to -60℃) and maintained for a set time (0.1 to 99 min). The sample gas enters the inner cavity 112 of the micro-etched chip 11 under the control of the mass flow meter 20 (10 to 100 mL / min). The target component is adsorbed and captured by the filler, and the unadsorbed gas is discharged by the vacuum pump 40.

[0057] During the desorption and injection stage, refer to Figure 6 As shown, Figure 6 The diagram shows the connection of the six-way switching valve 30 during the desorption and sample introduction stage. After adsorption and collection are completed, the six-way switching valve 30 switches to the sample introduction state. At this time, the internal pipelines of the first connection port 1 and the sixth connection port 6 of the six-way switching valve 30 are connected, the internal pipelines of the fourth connection port 4 and the fifth connection port 5 are connected, and the internal pipelines of the second connection port 2 and the third connection port 3 are connected. The heating unit is started, and the temperature is raised to the target temperature (80-150℃) and held for 0-1 min to allow the captured target components to be rapidly desorbed. The carrier gas sends the desorbed sample gas to the analyzer 60 through the gas flow transmission line (temperature 60-150℃), triggering the analyzer 60 to start analysis.

[0058] After the end of the desorption sampling phase, the system is automatically reset to the ready state, and the above concentration-sampling process is repeated according to the set program, realizing sequential operation, reducing waiting time and reducing human error.

[0059] The working performance of the present application is tested in combination with examples, and the analytical instrument 60 is taken as an example of a gas chromatograph, which is used to analyze trace sulfides in hydrogen energy sample gas by using the chip-type concentration module 10 in combination with the analytical instrument 60; wherein the chromatographic analysis conditions are, for example: chromatographic column DB-Sulfur (60m x 320μm x 4.2μm), flow rate 2mL / min; injection port 200℃; column oven conditions 40℃ for 4min, 15℃ / min to 200℃ for 8min; split ratio 4:1; SCD interface temperature 150℃, burner temperature 850℃, hydrogen 80mL / min, nitrogen 40mL / min, oxygen 10mL / min, ozone 25mL / min. Performance indicator 1 is the refrigeration and heating rate test of the chip-type concentration module 10, which is shown in FIG. 6, which is the temperature change curve in the continuous three tests of the chip-type concentration module 10. Figure 7

[0060] A multi-point standard curve is established, and 1mmol / mol sulfide-containing gas standard substance (components: hydrogen sulfide, carbonyl sulfide, methyl mercaptan, ethyl mercaptan, carbon disulfide, thiophene, dimethyl disulfide mixed gas standard substance) is diluted by a dynamic diluter to 10.0nmol / mol of sulfide-containing gas standard substance. Based on the chip-type concentration module 10, different volumes (such as 10mL, 50mL, 100mL, etc.) of diluted standard gas are quantitatively adsorbed and captured, and are desorbed and sampled into a gas chromatography-sulfur chemiluminescence detector (GC-SCD) system for analysis. By correlating the gradient volume sampling with the response value, a multi-point calibration curve of the sulfide components is established; setting the concentration of 200mL as the standard sampling amount of the chip-type concentration module 10, the sampling amounts of 1000mL, 800mL, 400mL, 200mL, 100mL, 80mL, 50mL, 20mL, and 10mL are set in the control system program, which can obtain 9 calibration samples with contents equivalent to 100nmol / mol, 80.0nmol / mol, 40.0nmol / mol, 20.0nmol / mol, 10.0nmol / mol, 8.00nmol / mol, 5.00nmol / mol, 2.00nmol / mol, and 1.00nmol / mol of sulfides.

[0061] ​Performance index 2 assesses the performance consistency of the chip-type concentration module 10 through the repeatability of measurement results. Essentially, it infers the output stability of the instrument's core module by analyzing the "dispersion of results." The experiment requires focusing on key concentration parameters, controlling uniform conditions, and quantifying repeatability through RSD to comprehensively reflect the instrument's performance consistency level: better repeatability (smaller RSD) indicates superior performance consistency. A 1 mmol / mol sulfide-containing gaseous standard was diluted to 10.0 nmol / mol, then concentrated to 10 mL (equivalent to 1 nmol / mol). This concentration was repeated seven times, and the consistency of the concentration effect was measured. See Table 1 below for the measurement results of seven consecutive concentration injections of the 1 nmol / mol sulfide-containing gaseous standard.

[0062] Table 1. Repeatability of 7 consecutive concentrated injections of 1 nmol / mol sulfide-containing gaseous standard material

[0063]

[0064] Performance index 3 involves dynamically diluted sulfide-containing gaseous standard substances used in the experiment, with nine concentration gradients (1.00 nmol / mol to 100 nmol / mol). These standards are enriched by the chip-type concentration module 10 and then imported into the analytical instrument 60. Calibration curves for each component (such as hydrogen sulfide, carbonyl sulfide, ethanethiol, etc.) are established, and the linear correlation coefficient (R0) of the calibration curves is used as the criterion. 2 This serves as a basis for evaluating the performance of the concentrator.

[0065] See Figures 8-14 The figures shown are the component calibration curves for hydrogen sulfide, carbonyl sulfide, ethanethiol, dimethyl sulfide, carbon disulfide, thiophene, and dimethyl disulfide, respectively. Figures 8-14 Based on the calibration curve results, the R values ​​of the calibration curves for each component are... 2 All values ​​are greater than 0.999, indicating that the chip-type concentration module 10 can accurately quantify trace gas components within the set concentration range, with good linearity, which can meet the requirements for quantitative accuracy in high-sensitivity detection.

[0066] See Figures 15-16 As shown, Figure 15 Typical peak chromatograms of 10 nmol / mol sulfur-containing gaseous standard material concentrated in 10 mL and analyzed by gas chromatograph (equivalent to the detection result of the lowest concentration point in the calibration curve at 10 nmol / mol). Figure 16 The typical peak chromatogram of a 10 nmol / mol sulfur-containing gaseous standard concentrated to 1000 mL on a gas chromatograph (equivalent to the detection result of the highest concentration point in the calibration curve at 100 nmol / mol) is shown. Figures 15-16 In response to the work being done Figures 6-12The calibration curve data is obtained from the chromatographic analysis spectrum of the concentrated minimum and maximum concentration sulfur compound gas standard material prepared from the chromatographic workstation software; Figure 15 The characteristic peaks of each target sulfide (hydrogen sulfide, carbonyl sulfide, ethyl mercaptan, etc.) are clearly presented, and the peak shape is symmetrical and the baseline is smooth, indicating that even at very low concentrations, the chip type concentration module 10 can effectively capture the target component and desorb the sample, meeting the sensitivity requirements of trace detection. Figure 16 Mainly used to verify the linear response and stability of the chip type concentration module 10 in the high concentration range: the peak area of each component in the spectrum should be proportional to the concentration (consistent with the trend of the calibration curve), and there is no obvious peak shape distortion (such as tailing, flat peak), indicating that the adsorbent filled in the chip does not reach adsorption saturation at high concentration, and the concentration efficiency remains stable.

[0067] The miniaturized chip type pre-concentration device based on MEMS technology described in the embodiments of the present application has the following advantages compared to the prior art:

[0068] 1. The micro-electromechanical system (MEMS) technology is introduced, which can realize miniaturization, lightweight, high reliability and high integration of the device. The chip type concentration module 10 obtained by preparing an integrated chip type trapping and desorption sampling structure through a silicon-based etching process replaces the traditional pipe type trapping and desorption structure, realizes the reduction of the volume of the sampling system (<50uL), and reduces the heat capacity to 1 / 40 of the traditional pipe type, which significantly improves the heat response speed.

[0069] 2. The concentration structure uses a chip type concentration module 10. The chip type structure solves the problem of large dead volume in the pipe type trapping and desorption, reduces the influence of longitudinal diffusion of sample components after thermal desorption, improves the accuracy of sample size, and especially for low boiling point components, reduces the peak width by fast thermal desorption, and reduces the peak width by more than 10%.

[0070] 3. The chip type structure further reduces the overall structure size, and can realize miniaturization and integration with the machine box, which provides effective support for portable detection.

[0071] 4. The temperature control unit 13 adopts a multi-stage semiconductor refrigeration plate stacking structure, which can reduce the refrigeration temperature to-60℃ under the condition that the input power is less than or equal to 150W, and improve the trapping efficiency of trace components.

[0072] In the specification provided herein, a large number of specific details are described. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some examples, well-known methods, structures and techniques are not shown in detail in order not to obscure the understanding of the present specification.

[0073] Similarly, it is to be understood that the embodiments of the application can include hardwired and / or program modules and that the various embodiments of the application can be implemented by computer, electrical or hybrid circuits intended for use stand-alone, or can be implemented by a combination of these forms. In this case, at least one software program can be loaded into memory and, once it is executed by processor(s), it can cause the processing system to perform one or more of the methods described herein. Similarly, it is to be understood that, for brevity and clarity, the above description has focused on the various aspects of the application, and that the various features of the application have sometimes been grouped together in a single embodiment, figure, or description of related features. Other embodiments of the application will be readily apparent to those skilled in the art from this disclosure. The present application is intended to embrace all available variations and modifications of the application disclosed herein and to incorporate all such variations and modifications by reference herein. It is intended that the description and examples be considered exemplary only, with the true scope of the application being indicated only by the appended claims. Various modifications and alterations to this application can be made by those skilled in the art within the scope and spirit of the disclosure, which is not to be construed as limiting the scope of the application. All such modifications and alterations have been contemplated in advance by this disclosure. Each feature disclosed in this specification, and / or the claims, can be provided independently of all other features. The use of "including", "comprising" "attaching", "coupling" "connecting" "adapting", "mounting", "fastening", "securing" or variations thereof, in the detailed description, examples, and / or claims, is intended to encompass the addition of one or more features to, recitation of one or more features of claim elements or use of one or more features with the exclusion of some features.

Claims

1. A miniaturized chip-based preconcentration device based on MEMS technology, characterized in that, The microchip-based pre-concentration device based on MEMS technology comprises a chip-based concentration module, a mass flow meter, a six-port switching valve and a vacuum pump; the six-port switching valve comprises six connection ports, wherein the first connection port of the six-port switching valve is connected to a carrier gas source, the third connection port and the sixth connection port of the six-port switching valve are respectively connected to two ends of the chip-based concentration module, the fifth connection port of the six-port switching valve is connected to the inlet of the mass flow meter, the second connection port of the six-port switching valve is connected to an analytical instrument, and the fourth connection port of the six-port switching valve is connected to a sample gas outlet pipeline; the outlet of the mass flow meter is connected to the vacuum pump.

2. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 1, characterized in that: The microchip-based pre-concentration device based on MEMS technology further comprises a cabinet integrated with a control system and a power supply module, and the chip-based concentration module, the mass flow meter, the six-port switching valve and the vacuum pump are arranged in the cabinet; the chip-based concentration module, the mass flow meter, the six-port switching valve and the vacuum pump are electrically connected to the control system, and the chip-based concentration module, the mass flow meter, the six-port switching valve, the vacuum pump and the control system are electrically connected to the power supply module.

3. The miniaturized chip-based preconcentration device based on MEMS technology of claim 1, wherein: The chip-based concentration module comprises a micro-etching chip, a filling layer, a temperature control unit and a temperature measurement unit; the micro-etching chip is provided with the filling layer, the temperature control unit is embedded on the micro-etching chip or arranged on the upper surface or the lower surface of the micro-etching chip, and the temperature measurement unit is packaged in the micro-etching chip.

4. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 3, characterized in that: The filling layer is composed of an adsorbent material and a metal grid network.

5. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 3, characterized in that: The micro-etching chip comprises a base, an inner cavity and a cover plate; the base is made of silicon, and the base and the cover plate are bonded and sealed to form the sealed inner cavity.

6. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 5, characterized in that: The micro-etching chip further comprises a microfluidic dam and a microcolumn array; the inner cavity is provided with the microcolumn array, and the microcolumn array is covered with the filling layer; the outer side of the microcolumn array is provided with the microfluidic dam.

7. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 6, characterized in that: The cover plate is provided with a filler injection port communicating with the inner cavity at a region corresponding to the microcolumn array.

8. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 6, characterized in that: The cover plate is provided with an air inlet and an air outlet respectively communicating with the inner cavity at regions corresponding to the outer side of the microfluidic dam.

9. The miniaturized chip-based preconcentration device based on MEMS technology according to claim 8, characterized in that: The air inlet and the air outlet are respectively provided with airflow transmission lines, and the airflow transmission lines are capillary air tubes.

10. The miniaturized chip-based preconcentration device based on MEMS technology of claim 5, wherein: The inner cavity of the micro-etching chip is provided with a plurality of accommodation grooves, and the temperature measurement unit is arranged in the accommodation grooves.

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