Gas chromatography chip structure and preparation method thereof

Abstract

The invention provides a gas chromatography chip structure and a preparation method thereof, which are characterized in that a snake-shaped or spiral micro-channel, a carrier gas channel and a detection cavity which penetrate through a silicon substrate are arranged on the silicon substrate, and a complete flow path with a sandwich structure is formed by bonding an upper cover plate and a lower cover plate for sealing; therefore, three-dimensional integration of the micro-channel, the carrier gas channel and the detection cavity is realized, connecting pipelines of discrete devices are eliminated, dead volume and cold points are reduced, and response time is shortened; a collection electrode and a 3D bias electrode are arranged in the detection cavity, so that the electrode layout is optimized, and the ion collection efficiency is improved; by optimizing the shape and width design of the carrier gas channel and the micro-channel, the gas flow of the micro-channel and the carrier gas channel is matched, the plasma is stabilized, the detection limit is reduced, and rapid separation and detection of gas-phase substances are realized. Therefore, the detection sensitivity and the overall stability are remarkably improved, and efficient gas detection is achieved.

Description

Technical Field

[0001] The invention belongs to the field of micro-electromechanical systems and relates to a gas chromatography chip structure and a preparation method thereof. Background Art

[0002] Gas chromatography is an important technique for separating and detecting complex gas components. A gas chromatography system primarily consists of five components: gas flow, injection, temperature control, separation, and detection, with the chromatographic column and detector at its core. Traditional gas chromatography systems are bulky and power-hungry due to the bulky temperature control component, making them difficult to transport and carry. With the development of MEMS technology, micro-chromatographic columns and micro-detectors have emerged. Miniaturization of these discrete components has been widely researched to reduce size and power consumption. However, these discrete components require additional piping, which creates dead volume and cold spots, impacting chromatographic performance. To address these issues, researchers are integrating the micro-chromatographic column and micro-detector into a monolithic chip. Currently, most monolithic integrated gas chromatography chips use a thermal conductivity detector (TCD), which has low sensitivity and cannot respond to low gas concentrations. Furthermore, research on monolithic integrated gas chromatography chips has focused on the separation and detection of heavy hydrocarbons, with limited research on lighter, more challenging hydrocarbons. Existing studies on monolithic integrated gas chromatography chips combining a miniature helium discharge ionization detector and a miniature gas chromatography column all use a 2D bias electrode structure, i.e., a bias electrode and a collection electrode located on the same substrate. This electrode structure has poor ion collection efficiency, resulting in reduced detector response to light hydrocarbon gases.

[0003] Therefore, it is necessary to develop a new type of integrated gas chromatography chip with high sensitivity and light hydrocarbon detection capability.

[0004] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a gas chromatography chip structure and a preparation method thereof, so as to solve the problem of how to realize a portable, miniaturized, highly sensitive, low-cost and multifunctional detection device.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a gas chromatography chip structure, comprising:

[0007] A silicon substrate having a first surface and a second surface arranged opposite to each other; the silicon substrate including a microchannel, a carrier gas channel, and a detection cavity; the microchannel, the carrier gas channel, and the detection cavity extending through the silicon substrate; the microchannel having a first port and a first outlet arranged opposite to each other, the first outlet of the microchannel communicating with the detection cavity; the carrier gas channel having a second port and a second outlet arranged opposite to each other, the second outlet of the carrier gas channel communicating with the detection cavity;

[0008] an upper cover plate, the upper cover plate having a first surface and a second surface disposed opposite to each other, the second surface of the upper cover plate being in contact with the first surface of the silicon substrate, the second surface of the upper cover plate being provided with a third bias electrode; and the third bias electrode being located correspondingly in the collection cavity;

[0009] A lower cover plate, wherein the lower cover plate has a first surface and a second surface arranged opposite to each other, the first surface of the lower cover plate contacts the second surface of the silicon substrate, and the first surface of the lower cover plate is provided with a collecting electrode, a first bias electrode, and a second bias electrode; the collecting electrode, the first bias electrode, and the second bias electrode are all correspondingly located in the detection cavity.

[0010] Optionally, the microchannel is distributed in a serpentine structure or a spiral structure, and the cross-section of the microchannel includes a rectangle; the length of the microchannel ranges from 1 to 3 m, and the width of the microchannel ranges from 100 to 500 μm; the ratio of the width of the carrier gas channel to the width of the microchannel is 0.1 to 0.14.

[0011] Optionally, the microchannel is distributed in a serpentine structure, the first port and the first outlet of the microchannel are located on both sides of the serpentine structure, and the corners at the ends of the serpentine structure are flush with the first outlet of the microchannel.

[0012] Optionally, the detection cavity further includes an excitation cavity, a collection cavity and a third port; the excitation cavity is provided with an excitation electrode; the collection cavity is connected to the first outlet end of the microchannel to collect the target gas, and the collection cavity is connected to the third port to discharge the exhaust gas.

[0013] Optionally, a vertical projection of the third bias electrode covers the collecting electrode, and the first bias electrode and the second bias electrode are located on both sides of the collecting electrode.

[0014] The present invention also provides a method for preparing a gas chromatography chip structure, comprising the following steps:

[0015] Providing a silicon substrate having a first surface and a second surface opposite to each other, and forming a first mask layer on the first surface of the silicon substrate;

[0016] forming a fourth groove on the first surface of the silicon substrate, forming a first groove, a second groove, and a third groove on the second surface of the silicon substrate, and removing the first mask layer;

[0017] Providing a lower cover plate, and forming a collecting electrode, a first bias electrode, and a second bias electrode on the lower cover plate;

[0018] Bonding the second surface of the silicon substrate to the lower cover plate, the collecting electrode is correspondingly located in the third groove, the first bias electrode is correspondingly located in the first groove, and the second bias electrode is correspondingly located in the second groove;

[0019] The silicon substrate is patterned, and microgrooves, a carrier gas groove, and a detection groove are formed on the silicon substrate; the microgrooves, the carrier gas groove, and the detection groove extend through the silicon substrate to the surface of the lower cover plate; the microgrooves have a first port and a first outlet end that are oppositely disposed, and the first outlet end of the microgrooves is connected to the detection groove; the carrier gas grooves have a second port and a second outlet end that are oppositely disposed; the second outlet end of the carrier gas grooves is connected to the detection cavity; the collecting electrode, the first bias electrode, and the second bias electrode are all located in the detection groove;

[0020] providing an upper cover plate, and forming a third bias electrode on the upper cover plate;

[0021] The first surface of the silicon substrate is bonded to the upper cover plate, and the upper cover plate covers the micro groove, the carrier gas groove and the detection groove to form a sealed micro groove, a carrier gas channel and a detection cavity.

[0022] The present invention also provides another method for preparing a gas chromatography chip structure, comprising the following steps:

[0023] Providing a silicon substrate having a first surface and a second surface opposite to each other, and forming a first mask layer on the first surface of the silicon substrate;

[0024] forming a fourth groove on the first surface of the silicon substrate, forming a first groove, a second groove, and a third groove on the second surface of the silicon substrate, and removing the first mask layer;

[0025] providing an upper cover plate, and forming a third bias electrode on the upper cover plate;

[0026] Bonding the first surface of the silicon substrate to the upper cover plate, wherein the third bias electrode corresponds to the fourth groove;

[0027] The silicon substrate is patterned, and microgrooves, gas carrier grooves, and detection grooves are formed on the silicon substrate; the microgrooves, gas carrier grooves, and detection grooves extend through the silicon substrate to the surface of the upper cover plate; the microgrooves have a first port and a first outlet end that are oppositely disposed, and the first outlet end of the microgrooves is connected to the detection groove; the gas carrier grooves have a second port and a second outlet end that are oppositely disposed; the second outlet end of the gas carrier grooves is connected to the detection cavity; the third bias electrode is located in the detection groove;

[0028] Providing a lower cover plate, forming a collecting electrode, a first bias electrode, and a second bias electrode on the lower cover plate, wherein the collecting electrode, the first bias electrode, and the second bias electrode are all located in the detection groove;

[0029] The second surface of the silicon substrate is bonded to the lower cover plate, and the micro groove, the carrier gas groove and the detection groove are covered by the lower cover plate to form a sealed micro channel, a carrier gas channel and a detection cavity.

[0030] Optionally, a vertical projection of the fourth groove covers the third groove, and the first groove and the second groove are located on both sides of the third groove.

[0031] Optionally, the micro groove, the gas carrier groove and the detection groove are formed by dry etching.

[0032] Optionally, the bonding method of the silicon substrate, the upper cover plate and the lower cover plate includes one of anodic bonding, fusion bonding, eutectic bonding or low-temperature bonding.

[0033] The present invention provides a gas chromatography chip structure and a preparation method thereof. By setting a serpentine or spiral microchannel, a carrier gas channel and a detection cavity that penetrate the silicon substrate on a silicon substrate, and bonding the upper and lower cover plates to seal to form a complete flow path of a sandwich structure, the microchannel, the carrier gas channel and the detection cavity are simultaneously integrated in three dimensions on the silicon substrate, thereby eliminating the connecting pipelines of discrete devices, saving processes, forming a closed analysis path, reducing dead volume and cold spots, and shortening response time; by setting a collecting electrode and a 3D bias electrode in the detection cavity, optimizing the electrode layout, and improving the ion collection efficiency compared with the 2D bias electrode structure; by optimizing the shape and width design of the carrier gas channel and the microchannel to match the gas flow of the microchannel and the carrier gas channel, the plasma is stabilized, the detection limit is reduced, and the rapid separation and detection of light hydrocarbons is achieved. Therefore, the present invention significantly improves the detection sensitivity and overall stability, and realizes efficient gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1It shows a partially tilted top view of the gas chromatography chip of the present invention.

[0035] Figure 2 Shown is a partially enlarged schematic diagram of the gas chromatography chip of the present invention.

[0036] Figure 3 It shows the effect of the change of the width of the carrier gas channel of the gas chromatography chip on the gas flow rate in the present invention.

[0037] Figure 4 Shown is a schematic diagram of the process flow for preparing the gas chromatography chip in Example 2 of the present invention.

[0038] Figure 5 It shows a schematic structural diagram after a silicon substrate is provided and an oxide layer is formed on the surface in the second embodiment of the present invention.

[0039] Figure 6 It shows a schematic structural diagram after the electrode groove is formed in the second embodiment of the present invention.

[0040] Figure 7 It shows a schematic diagram of the structure after the oxide layer is removed in the second embodiment of the present invention.

[0041] Figure 8 It shows a schematic structural diagram after providing a lower cover plate and forming a metal electrode layer in the second embodiment of the present invention.

[0042] Figure 9 It is a schematic structural diagram showing the structure after the collecting electrode, the first bias electrode and the second bias electrode are formed on the lower cover plate in the second embodiment of the present invention.

[0043] Figure 10 It shows a schematic structural diagram of the second embodiment of the present invention after the silicon substrate is bonded to the lower cover.

[0044] Figure 11 It shows a schematic structural diagram after the micro grooves, the gas carrier grooves and the detection grooves are formed in the second embodiment of the present invention.

[0045] Figure 12 It is a schematic structural diagram showing a structure in which an upper cover plate is provided and a third bias electrode is formed in the second embodiment of the present invention.

[0046] Figure 13 It shows a schematic structural diagram of the second embodiment of the present invention after the silicon substrate is bonded to the upper cover plate.

[0047] Figure 14 The figure shows the separation and detection chromatogram of light hydrocarbon components by the gas chromatography chip of the present invention at 90°C.

[0048] Figure 15 Shown is a schematic diagram of the process flow for preparing the gas chromatography chip in Example 3 of the present invention.

[0049] Figure 16 It shows a schematic structural diagram after providing an upper cover plate and forming a third bias electrode in the third embodiment of the present invention.

[0050] Figure 17 It shows a schematic structural diagram of the silicon substrate after being bonded to the upper cover plate in the third embodiment of the present invention.

[0051] Figure 18 It shows a schematic structural diagram after the micro grooves, the gas carrier grooves and the detection grooves are formed in the third embodiment of the present invention.

[0052] Figure 19 It shows a schematic structural diagram after providing a lower cover plate and forming a collecting electrode, a first bias electrode and a second bias electrode in the third embodiment of the present invention.

[0053] Description of Reference Numerals

[0054] 100 Upper cover

[0055] 200 silicon substrate

[0056] 210 first mask layer

[0057] 221 First Groove

[0058] 222 Second groove

[0059] 223 Fourth Groove

[0060] 224 Third Groove

[0061] 300 microchannels

[0062] 310 First Port

[0063] 320 First Exit

[0064] 330 micro grooves

[0065] 400 carrier gas channels

[0066] 410 Second Port

[0067] 420 Second Exit

[0068] 500 detection chamber

[0069] 510 excitation cavity

[0070] 511 Excitation electrode

[0071] 520 Collection Chamber

[0072] 521 first bias electrode

[0073] 522 second bias electrode

[0074] 523 Third bias electrode

[0075] 524 Collection Electrode

[0076] 525 metal electrode layer

[0077] 530 Third Port

[0078] 540 Detection Groove

[0079] 600 lower cover

[0080] 610 second mask layer

[0081] 620 third mask layer DETAILED DESCRIPTION

[0082] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0083] For example, when describing the embodiments of the present invention, cross-sectional views of device structures may be partially enlarged and not to scale for ease of explanation. Furthermore, these schematic views are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual fabrication, the three-dimensional dimensions of length, width, and depth should be included.

[0084] For ease of description, spatially relative terms such as "under," "below," "below," "below," "above," and "on" may be used herein to describe the relationship of one element or feature to other elements or features shown in the drawings. It will be understood that these spatially relative terms are intended to encompass orientations of the device in use or operation in addition to the orientation depicted in the drawings. Additionally, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may be present. As used herein, "between" is inclusive of both endpoints.

[0085] In the context of the present application, a structure described as a first feature being "above" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where an additional feature is formed between the first and second features, such that the first and second features may not be in direct contact.

[0086] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0087] Example 1

[0088] See Figures 1 to 19 This embodiment proposes a gas chromatography chip structure, which will be described below in conjunction with the accompanying drawings.

[0089] See Figure 1 The gas chromatography chip structure includes a silicon substrate 200, an upper cover plate 100 and a lower cover plate 600.

[0090] The silicon substrate 200 has a first surface and a second surface arranged opposite to each other; the silicon substrate 200 includes a microchannel 300, a carrier gas channel 400, and a detection cavity 500; the microchannel 300, the carrier gas channel 400, and the detection cavity 500 pass through the silicon substrate 200; the microchannel 300 has a first port 310 and a first outlet end 320 arranged opposite to each other, and the first outlet end 320 of the microchannel 300 is connected to the detection cavity 500; the carrier gas channel 400 has a second port 410 and a second outlet end 420 arranged opposite to each other, and the second outlet end 420 of the carrier gas channel 400 is connected to the detection cavity 500;

[0091] The upper cover plate 100 has a first surface and a second surface opposite to each other. The second surface of the upper cover plate 100 contacts the first surface of the silicon substrate 200. A third bias electrode 523 is provided on the second surface of the upper cover plate 100. The third bias electrode 523 is located corresponding to the collecting cavity 520.

[0092] The lower cover plate 600 has a first surface and a second surface arranged opposite to each other. The first surface of the lower cover plate 600 contacts the second surface of the silicon substrate 200. The first surface of the lower cover plate 600 is provided with a collecting electrode 524, a first bias electrode 521 and a second bias electrode 522; the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 are all correspondingly located in the detection cavity 500.

[0093] Specifically, the stationary phase on the inner wall of the microchannel 300 is deposited or bonded with a related chromatographic stationary phase material to achieve selective separation of mixed gases; the microchannel 300 has a channel with a high aspect ratio and is a microchannel obtained by dry etching a long path on the silicon substrate 200.

[0094] As an example, the length of the microchannel 300 ranges from 1 to 3 m, and the width of the first outlet end 320 of the microchannel 300 ranges from 100 to 500 μm.

[0095] The length of the microchannel 300 is in the range of 1 to 3 m, such as 1 m, 1.5 m, 2 m, 2.5 m, and 3 m, and any value within this range. The width of the first outlet end 320 of the microchannel 300 is in the range of 100 to 500 μm, such as 100 μm, 200 μm, 300 μm, 400 μm, and 500 μm, and any value within this range. The above structure increases the contact time between the gas and the stationary phase. Of course, the size setting of the microchannel 300 is not limited to this.

[0096] As an example, the microchannels 300 are distributed in a serpentine or spiral shape, and the cross section of the microchannels 300 includes a rectangle.

[0097] For details, see Figure 1 , the microchannel 300 is designed to be a serpentine structure or a spiral structure; by optimizing the corner curvature radius of the serpentine structure, the flow rate loss at the corner is compensated and the uniformity and smoothness are maintained; in the present embodiment, the shape of the microchannel 300 is serpentine, and preferably, all the corners in the microchannel 300 are arc-shaped to reduce gas eddy currents, extend the sample passage path, improve reaction sensitivity, and thus improve gas phase separation efficiency. In other embodiments, the microchannel 300 is spirally distributed, and the eddy currents are reduced by smoothing the corners to improve gas phase separation efficiency. Of course, in some other embodiments, the microchannel 300 can also be extended in any extension manner in the silicon substrate, such as broken line extension, U-shaped extension, spiral extension, etc., which is not overly restricted here.

[0098] As an example, the ratio of the width of the second outlet end 420 of the carrier gas channel 400 to the width of the first outlet end 320 of the microchannel 300 is in a range of 0.1 to 0.14.

[0099] Specifically, the carrier gas channel 400 and the detection cavity 500 constitute the core part of the miniature helium ionization detector. The carrier gas channel 400 is realized by silicon etching processing and is used to transport high-purity helium (>99.999%) as a carrier gas and discharge medium; the second port 410 is used for the input of helium and to maintain the purity of helium. In addition, the second port 410 of the carrier gas channel 400 is provided with a purification module. Therefore, the caliber of the second port 410 is larger than the caliber of the second outlet port 420, which is used to connect the capillary and integrate the purification module to remove helium impurities and stabilize the airflow. The second outlet port 420 is directly connected to the detection cavity 500 and is equipped with a flow detector and a pressure regulating valve to ensure the precise control of the helium flow rate, which facilitates the subsequent detection stability of the detection cavity 500.

[0100] For further information, see Figure 2 It is a partial enlarged schematic diagram of the gas chromatography chip in the detection cavity, wherein the position A1B1 represents the second outlet end 420 of the microchannel, and the position A2B2 represents the first outlet end 320 of the carrier gas channel; Figure 3 The effect of the change in the width relationship between the microchannel and the second outlet end 420 of the carrier gas channel on the corresponding gas flow rate is shown. Therefore, the stability of the gas flow field directly affects the detection sensitivity. By optimizing the ratio of the width of the second outlet end 420 to the width of the first outlet end 320 to perform flow matching, it is ensured that the analyte is fully ionized before entering the collection chamber 520, thereby having a greater impact on the improvement of detection sensitivity. The ratio of the width of the second outlet end 420 to the width of the first outlet end 320 of the microchannel is in the range of 0.1 to 0.14, for example, any value within this range such as 0.1, 0.11, 0.12, 0.13, and 0.14.

[0101] In this embodiment, the gas flow rate of the microchannel 300 ranges from 1 mL / min to 8 mL / min. The specific ratio can be adjusted according to the actual channel size. In addition, in this embodiment, when the width of the first outlet port 320 is set to 400 μm and the length is 2 m, the same column front pressure of 3 KPa is applied to the first port 310 and the second port 410 of the microchannel 300. If the width of the microchannel 300 is set to 48 μm, the flow rates of the gases in the two channels can be at the same order of magnitude. This optimization makes the plasma more stable, the analytes are fully ionized, and the detection sensitivity is improved by 1000 times. Figure 14The chromatogram shown is a separation and detection chromatogram of light hydrocarbon components at 90°C using the gas chromatography chip described in this embodiment. The detection target in this embodiment is the propane content in a mixed gas. Testing shows a detection limit of 32 pg for propane. In other embodiments, the ratio of the width of the second outlet 420 to the outlet width of the microchannel 300 is not limited to this ratio and can be further determined based on the actual dimensions of the microchannel 300 and the carrier gas channel 400.

[0102] As an example, the detection chamber 500 also includes an excitation chamber 510, a collection chamber 520 and a third port 530; the excitation chamber 510 is provided with an excitation electrode; the collection chamber 520 is connected to the first outlet end 320 of the microchannel 300 to collect the target gas, and the collection chamber 520 is connected to the third port 530 to discharge the exhaust gas.

[0103] For details, see Figure 1 The excitation electrode 511 in the discharge chamber is a body excitation electrode, and the diameter of the metal wire of the body excitation electrode ranges from 0.1 mm to 0.2 mm. The excitation voltage is 300 to 600 V, which can effectively excite helium for ionization and form a stable plasma. This excitation voltage range ensures sufficient ionization energy while avoiding excessive energy loss. The lower excitation voltage helps reduce electrochemical corrosion and heat loss of the electrode, thereby extending the service life of the electrode.

[0104] Furthermore, the outlet of the microchannel 300 communicates with the collection chamber 520 of the detection chamber 500, forming a closed analysis path. The analytical gas can enter the collection chamber directly along the microchannel 300, reducing the risk of external contamination, reducing dead volume, and improving detection sensitivity and accuracy. At the same time, exhaust gas can be smoothly discharged to avoid accumulation within the system, thus optimizing the gas flow path and improving detection efficiency and sensitivity.

[0105] As an example, a vertical projection of the third bias electrode 523 covers the collecting electrode 524 , and the first bias electrode 521 and the second bias electrode 522 are located on both sides of the collecting electrode 524 .

[0106] For details, see Figure 1The collecting electrode 524 in the collecting chamber 520 and the first bias electrode 521, the second bias electrode 522 and the third bias electrode 523 all use thin film electrodes, wherein the first bias electrode 521, the second bias electrode 522 and the third bias electrode 523 are designed as 3D bias electrodes surrounding the collecting electrode 524; by setting up a 3D bias electrode, a stable electric potential is provided for the movement of ions, guiding the directional movement of ions, enhancing the electric field strength and optimizing the distribution uniformity, thereby improving the ion collection efficiency and detection sensitivity.

[0107] As an example, the collecting electrode 524, the first bias electrode 521, the second bias electrode 522 and the third bias electrode 523 can adopt a metal thin film structure such as Au, Pt, etc., and its thin layer structure can increase the specific surface area to improve the adsorption and transmission efficiency of ions, and shorten the ion transmission path to speed up the response time.

[0108] Furthermore, before preparing the electrode, the lower cover plate 600 needs to be cleaned and pre-treated to remove surface impurities and contaminants, and then a metal film is deposited through a PVD process to ensure that the thickness and uniformity are controllable.

[0109] As an example, the microchannel 300 is distributed in a serpentine structure, the first port 310 and the second outlet 420 of the microchannel 300 are located on both sides of the serpentine channel, and the corners of the serpentine structure ends are flush with the first outlet 320 of the microchannel 300.

[0110] For details, see Figure 1 The silicon substrate 200 is further provided with a first side (adjacent to the first port 310) and a second side (adjacent to the first outlet end 320) that are arranged opposite to each other. The first port 310 and the carrier gas channel 400 are arranged parallel or perpendicular to each other on the first side. The corners at the ends of the serpentine structure are aligned with the first outlet end 320. By suppressing local losses and secondary flows, the outlet airflow is kept consistent with the main flow direction, thereby optimizing the uniformity of the velocity distribution and avoiding the generation of biased flow.

[0111] As an example, the carrier gas channel 400 is parallel to the serpentine structure of the microchannel 300 .

[0112] Specifically, by arranging the carrier gas channel 400 and the serpentine channel of the microchannel 300 in parallel, the helium flow direction is consistent with the airflow direction in the microchannel 300. This directional flow can reduce turbulent interference and improve the carrier gas transmission efficiency; helium flows directly into the excitation chamber through the carrier gas channel 400, and its flow direction is synchronized with the airflow of the microchannel 300, thereby stabilizing the airflow dynamics environment in the plasma excitation area, suppressing plasma flicker, improving excitation efficiency, and being more suitable for continuous detection of low-concentration samples. Therefore, this design can further improve the test sensitivity by further optimizing the airflow distribution. In other embodiments, the arrangement of the carrier gas channel 400 and the serpentine channel of the microchannel 300 is not limited to this.

[0113] Of course, in some other embodiments, a heater and a temperature sensor are integrated on the back of the silicon substrate 200 to achieve program control and optimize separation efficiency, but this is not limited to this and will not be described in detail here.

[0114] Example 2

[0115] This embodiment provides a method for preparing a monolithic integrated gas chromatography chip. The following will introduce the method for preparing the gas chromatography chip structure in conjunction with the accompanying drawings. Figure 1 The dotted line MNL in FIG is a cross-sectional view of the path. The following is a further introduction to the preparation method of the gas chromatography chip structure, which mainly includes the following steps:

[0116] See Figure 4 and Figure 5 , performing step S2 - 1 , providing a silicon substrate 200 , wherein the silicon substrate 200 has a first surface and a second surface opposite to each other, and forming a first mask layer 210 on the first surface of the silicon substrate 200 .

[0117] Specifically, before depositing the first mask layer 210, the surface of the silicon substrate 200 must be highly cleaned to ensure good adhesion. The first mask layer 210 is formed on the first and second surfaces of the silicon substrate 200. The material of the first mask layer 210 includes silicon oxide, silicon nitride, and the like. The material of the first mask layer 210 is deposited on the first surface of the silicon substrate 200 using a CVD, PVD, or thermal oxidation process. In this embodiment, the mask layer is formed using a thermal oxidation process to form silicon oxide as the first mask layer 210.

[0118] See Figure 4 、 Figure 6 and Figure 7, performing step S2 - 2 to form a fourth groove 223 on the first surface of the silicon substrate 200 , and forming a first groove 221 , a second groove 222 and a third groove 224 on the second surface of the silicon substrate 200 .

[0119] Specifically, photoresist is coated on the first and second surfaces of the silicon substrate 200, and the patterns of the first groove 221 to the fourth groove 223 are transferred to the photoresist through a photolithography process; the first mask layer 210 is patterned using the photoresist as a mask; and the first groove 221, the second groove 222, the third groove 224, and the fourth groove 223 are formed through an etching process. The etching process can be dry etching or wet etching; in this embodiment, refer to Figure 6 , silicon oxide is patterned in a BOE solution using a photoresist as a mask, and then the silicon substrate is wet-etched to form the fourth groove 223 on the first surface of the silicon substrate, and the first groove 221, the second groove 222, and the third groove 224 on the second surface of the silicon substrate. The wet etching solution is a KOH solution, but the preparation method of the first groove 221 to the fourth groove 223 is not limited to this. Of course, in other embodiments, a silicon nitride layer or a combination of silicon oxide and silicon nitride can also be selected as the first mask layer 210, depending on the actual etching conditions; see Figure 7 After etching is completed, the photoresist and the first mask layer 210 are removed.

[0120] As an example, a vertical projection of the fourth groove 223 covers the third groove 224 , and the first groove 221 and the second groove 222 are located on both sides of the third groove 224 .

[0121] For details, see Figure 7 The fourth groove 223 provides space and position for the subsequent placement of the third bias electrode 523; the first groove 221 and the second groove 222 provide space and position for the subsequent placement of the first bias electrode 521 and the second bias electrode 522 respectively; the third groove 224 provides space and position for the subsequent placement of the collecting electrode 524.

[0122] Furthermore, by positioning the first groove 221 to the fourth groove 223, the spatial design of the subsequent 3D bias electrode is achieved, thereby providing a stable electric potential for the direction of ion movement, guiding the direction of ion movement, enhancing the electric field strength, and thus improving ion collection efficiency. In other embodiments, the positional relationship between the first groove 221, the second groove 222, the third groove 224, and the fourth groove 223 is not limited to this.

[0123] See Figure 4 、 Figure 8 and Figure 9 , perform step S2 - 3 , provide a lower cover plate 600 , and form the collecting electrode 524 , the first bias electrode 521 and the second bias electrode 522 on the lower cover plate 600 .

[0124] Specifically, the lower cover plate 600 usually serves as a supporting structure of the device and has good mechanical strength, insulation performance and compatibility with the upper structure; the lower cover plate 600 includes one of a silicon cover plate, a glass cover plate or a ceramic cover plate.

[0125] Furthermore, the collecting electrode 524 is used to capture and collect target ions for subsequent detection or analysis, and is located at the center of the subsequent detection cavity 500 for receiving and accumulating ion signals. The collecting electrode 524 absorbs and captures ions under a certain electric field. When the ions reach the surface of the collecting electrode, a current signal is generated and detected and converted into data. The first bias electrode 521 and the second bias electrode 522 are located on both sides of the collecting electrode 524 and are combined with the subsequent third bias electrode 523 to stabilize the electric field for the subsequent collecting electrode 524 in three-dimensional space to guide ion movement and improve ion collection efficiency. The thickness and spacing of the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 will also affect the performance of the device to a certain extent, which will not be described in detail here. In other embodiments, the positional relationship between the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 is not limited to this.

[0126] As an example, the metal material used for the collecting electrode 524, the first bias electrode 521, and the second bias electrode 522 includes one of Au and Pt. The thin-layer structure of the thin-film electrode increases the specific surface area, improves ion adsorption and transmission efficiency, shortens the transmission path, and improves response time. Of course, the materials used for the collecting electrode 524, the first bias electrode 521, and the second bias electrode 522 are not limited to these.

[0127] Furthermore, the collecting electrode 524, the first bias electrode 521, and the second bias electrode 522 are formed by forming a metal electrode layer 525 on the surface of the lower cover plate 600 using a PVD process, then forming a second mask layer 610 on the surface of the metal electrode layer 525 using a CVD process, and then performing an etching process. The second mask layer 610 protects the electrodes during the subsequent etching of the metal electrode layer 525. In this embodiment, silicon oxide is formed using a PECVD process, and the metal electrode layer 525 is subsequently etched using a dry etching process, thereby forming the collecting electrode 524, the first bias electrode 521, and the second bias electrode 522.

[0128] See Figure 4 and Figure 10 , execute step S2-4, bond the second surface of the silicon substrate to the lower cover 600, the collecting electrode 524 corresponds to the third groove 224, the first bias electrode 521 corresponds to the first groove 221, and the second bias electrode 522 corresponds to the second groove 222.

[0129] Specifically, the second surface of the silicon substrate is bonded to the lower cover plate 600 to form a partial structure. The lower cover plate 600 includes one of a glass cover plate, a ceramic cover plate, and a silicon cover plate. In this embodiment, the lower cover plate 600 is a glass cover plate.

[0130] As an example, the bonding method includes one of anodic bonding, fusion bonding, eutectic bonding or low temperature bonding.

[0131] Specifically, anodic bonding is used with the assistance of an electric field to bond glass to silicon at 300-450°C, which has the advantages of high bonding strength, good sealing and low temperature; melt bonding uses high temperature (800-1100°C) to diffuse and bond surface atoms, with high bonding strength and good thermal stability, but has high surface requirements and high temperature; eutectic bonding uses eutectic metal (such as Au-Si) to melt at around 430°C to form a bond, which has the characteristics of low-temperature bonding, planarization and high conductivity; when selecting a bonding method, it is necessary to comprehensively consider factors such as material compatibility, bonding temperature, bonding strength, process complexity and cost to meet specific application requirements. In this embodiment, the bonding method uses anodic bonding to achieve silicon glass bonding between glass and the lower cover plate 600.

[0132] It is worth noting that during the bonding process between the second surface of the silicon substrate and the lower cover plate 600, the second mask layer 610 above the film layer of the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 remains above the electrodes, thereby further protecting the electrodes during the subsequent etching of the silicon substrate to form grooves.

[0133] See Figure 4 and Figure 10, execute step S2-5, pattern the silicon substrate, and prepare micro grooves 330, carrier gas grooves (unmarked) and detection grooves 540 on the silicon substrate; the micro grooves 330, the carrier gas grooves and the detection grooves 540 penetrate the silicon substrate and extend to the surface of the lower cover plate 600; the micro grooves 330 have a first port 310 and a first outlet end 320 arranged opposite to each other, and the first outlet end 320 of the micro groove 330 is connected to the detection groove 540; the carrier gas groove has a second port 410 and a second outlet end 420 arranged opposite to each other; the second outlet end 420 of the carrier gas groove is connected to the detection groove 540; the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 are all located in the detection groove 540.

[0134] Specifically, the silicon substrate is patterned, and dry etching is used to form the microgrooves 330, the carrier gas grooves, and the detection grooves 540. The collecting electrode 524, the first bias electrode 521, and the second bias electrode 522 are all located in the detection grooves 540. It should be noted that the fourth groove 223 in the figure is not completely etched to form the detection groove 540. Part of the fourth groove 223 is used for the lead and lead pad of the third bias electrode 523, which is not shown in the figure.

[0135] Furthermore, the microgrooves 330, the carrier gas grooves and the detection grooves 540 form a closed communication system after subsequent bonding to the cover plate 100. After the microgrooves 330 are closed, they are used to transmit or guide tiny fluids or gases. The first outlet end 320 of the microgrooves 330 is connected to the detection grooves 540 for guiding the fluids or gases to the detection area. After the carrier gas grooves are closed, they are used to transmit carrier gas, and the second outlet end 420 of the carrier gas grooves is connected to the detection grooves 540 for introducing the carrier gas into the detection area after closing; after the carrier gas grooves are closed, they are used to accommodate detection electrodes (such as the collecting electrode 524, the first bias electrode 521, the second bias electrode 522 and the subsequent third bias electrode 523) and serve as the detection area. The detection grooves 540 are connected to the microgrooves 330 and the carrier gas grooves, and form a complete detection system after closing.

[0136] As an example, the micro grooves 330 are distributed in a serpentine shape or a spiral shape, and the cross section of the micro grooves 330 includes a rectangle.

[0137] Specifically, the collective distribution of the microgrooves 330 adopts a serpentine structure or a spiral layout with a rectangular cross-section to extend the sample passage path and improve the separation efficiency. The corners adopt arc transition to reduce gas eddy currents and maintain flow rate uniformity. In other embodiments, the microgrooves 330 are distributed in a spiral shape. In the microchannel 300 formed by subsequent closure, the smooth corners can further reduce flow resistance, reduce gas eddy currents, improve reaction sensitivity, and thus improve gas phase separation efficiency. Of course, in other examples, the formed microgrooves 330 can also be extended in any extension manner in the silicon substrate, such as broken line extension, U-shaped extension, spiral extension, etc., which are adjusted according to the separation requirements and are not overly restricted here.

[0138] See Figure 4 and Figure 12 , perform step S2 - 6 , provide an upper cover plate 100 , and form the third bias electrode 523 on the upper cover plate 100 .

[0139] Specifically, the upper cover 100 protects the internal structure from the influence of the external environment (such as humidity and dust), and provides mechanical support for the subsequent detection cavity 500 and electrodes; in addition, by providing a spatial position for installing the third bias electrode 523, electrical control of the detection process can be achieved.

[0140] As an example, the metal material used for the third bias electrode 523 includes one of Au and Pt. The third bias electrode 523 employs a thin-layer structure, such as a thin-film electrode, which increases the specific surface area and improves ion adsorption and transmission efficiency. Furthermore, the thin-layer structure reduces the ion transmission path and improves the response time of the detection system. Of course, the material of the third bias electrode 523 is not limited to this.

[0141] Furthermore, the process of forming the third bias electrode 523 is the same as that of forming the first bias electrode 521 , the second bias electrode 522 and the collecting electrode 524 , and will not be repeated here.

[0142] See Figure 4 and Figure 13 , execute step S2-7, bond the first surface of the silicon substrate to the upper cover plate 100, and cover the micro groove 330, the carrier gas groove and the detection groove 540 with the upper cover plate 100 to form a sealed micro channel 300, the carrier gas channel 400, and the detection cavity 500.

[0143] Specifically, the first surface of the silicon substrate is bonded to the upper cover plate 100 to ensure that the micro groove 330, the carrier gas groove and the detection groove 540 are completely covered by the upper cover plate 100, thereby forming a sealed micro channel 300, the carrier gas channel 400 and the detection cavity 500, thereby realizing the functions of fluid transmission, gas transmission and signal detection.

[0144] Furthermore, the third bias electrode 523 is located in the detection cavity 500 and above the collecting electrode 524. Together with the first bias electrode 521 and the second bias electrode 522, they surround the collecting electrode 524 to form a 3D bias electrode, which stabilizes the movement direction of ions, enhances the electric field strength, and improves the ion collection efficiency and detection sensitivity.

[0145] Furthermore, the present invention constructs a sandwich structure of an upper cover plate-silicon substrate-lower cover plate, integrating the detection device and the separation device, that is, the microchannel, the carrier gas channel and the detection cavity are prepared on the same silicon substrate 200, which simplifies the process steps, improves the test efficiency, and optimizes the detection performance.

[0146] As an example, the length of the microchannel 300 ranges from 1 to 3 m, and the width of the first outlet end 320 of the microchannel 300 ranges from 100 to 500 μm.

[0147] Specifically, the microchannel 300 is formed by depositing or bonding relevant chromatographic stationary phase materials on the inner wall of the channel to achieve selective separation of mixed gases; the microchannel 300 has a channel with a high aspect ratio and is a microstructure obtained by etching a long path on the silicon substrate 200 by dry etching. The length of the microchannel 300 is in the range of 1 to 3 m, such as 1 m, 1.5 m, 2 m, 2.5 m and 3 m, etc. Any value within this range. The width of the first outlet end 320 of the microchannel 300 is in the range of 100 to 500 μm, such as 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, etc. Any value within this range. The above structure increases the contact time between the gas and the stationary phase. Of course, the size setting of the microchannel 300 is not limited to this.

[0148] As an example, the ratio of the width of the second outlet end 420 of the carrier gas channel 400 to the width of the first outlet end 320 of the microchannel 300 is in a range of 0.1 to 0.14.

[0149] For further information, see Figure 2 The gas flow field shown is the second outlet port 420 and the first outlet port 320; Figure 3The effect of the change in the width of the second outlet end 420 of the carrier gas channel on the gas flow rate is shown. Therefore, the stability of the gas flow field directly affects the detection sensitivity. By optimizing the ratio of the width of the second outlet end 420 to the width of the first outlet end 320 to perform flow matching, it is ensured that the analyte is fully ionized before entering the collection chamber 520, thereby having a greater impact on the improvement of detection sensitivity. The ratio of the width of the second outlet end 420 to the width of the first outlet end 320 of the microchannel 300 is in the range of 0.1 to 0.14, for example, any value within this range such as 0.1, 0.11, 0.12, 0.13, and 0.14.

[0150] In this embodiment, the gas flow rate of the microchannel 300 ranges from 1 mL / min to 8 mL / min. The specific ratio can be adjusted according to the actual channel size. In addition, in this embodiment, when the width of the first outlet port 320 is set to 400 μm and the length is 2 m, the same column front pressure of 3 KPa is applied to the first port 310 and the second port 410 of the microchannel 300. If the width of the microchannel 300 is set to 48 μm, the flow rates of the gases in the two channels can be at the same order of magnitude. This optimization makes the plasma more stable, the analytes are fully ionized, and the detection sensitivity is improved by 1000 times. Figure 14 The chromatogram shown is a separation and detection chromatogram of light hydrocarbon components at 90°C using the gas chromatography chip described in this embodiment. The detection target in this embodiment is the propane content in a mixed gas. Testing shows a detection limit of 32 pg for propane. In other embodiments, the ratio of the width of the second outlet 420 to the outlet width of the microchannel 300 is not limited to this ratio and can be further determined based on the actual dimensions of the microchannel 300 and the carrier gas channel 400.

[0151] As an example, the detection chamber 500 also includes an excitation chamber 510, a collection chamber 520 and a third port 530; the excitation chamber 510 is provided with an excitation electrode 511; the collection chamber 520 is connected to the first outlet end 320 of the microchannel 300 to collect the target gas, and the collection chamber 520 is connected to the third port 530 to discharge the exhaust gas.

[0152] Specifically, the excitation electrode 511 in the discharge chamber is a body excitation electrode, and the metal wire diameter of the body excitation electrode ranges from 0.1mm to 0.2mm. The excitation voltage is 300-600V, which can effectively excite helium to ionize and form a stable plasma. This excitation voltage range ensures sufficient ionization energy while avoiding excessive energy loss. The lower excitation voltage helps reduce electrochemical corrosion and heat loss of the electrode, thereby extending the service life of the electrode.

[0153] Furthermore, the outlet of the microchannel 300 communicates with the collection chamber 520 of the detection chamber 500, forming a closed analysis path. Analytical gas can enter the collection chamber directly along the microchannel 300, reducing the risk of external contamination, reducing dead volume, and improving detection sensitivity and accuracy.

[0154] As an example, the microchannel 300 is distributed in a serpentine structure, the first port 310 and the second outlet 420 of the microchannel 300 are located on both sides of the serpentine channel, and the corners of the serpentine structure ends are flush with the first outlet 320 of the microchannel 300.

[0155] For details, see Figure 1 The silicon substrate 200 is further provided with a first side (adjacent to the first port 310) and a second side (adjacent to the first outlet end 320) that are arranged opposite to each other. The first port 310 and the carrier gas channel 400 are arranged parallel or perpendicular to each other on the first side. The corners at the ends of the serpentine structure are aligned with the first outlet end 320. By suppressing local losses and secondary flows, the outlet airflow is kept consistent with the main flow direction, thereby optimizing the uniformity of the velocity distribution and avoiding the generation of biased flow.

[0156] As an example, the carrier gas channel 400 is parallel to the serpentine structure of the microchannel 300. Specifically, by arranging the carrier gas channel 400 and the serpentine channel of the microchannel 300 in parallel, the helium flow direction is consistent with the airflow direction in the microchannel 300. This directional flow can reduce turbulent interference and improve the carrier gas transmission efficiency; the helium flows directly into the excitation chamber through the carrier gas channel 400, and its flow direction is synchronized with the airflow of the microchannel 300, thereby stabilizing the airflow dynamics environment in the plasma excitation area, suppressing plasma flicker, improving excitation efficiency, and being more suitable for continuous detection of low-concentration samples. Therefore, this design can further improve the test sensitivity by further optimizing the airflow distribution. In other embodiments, the arrangement of the carrier gas channel 400 and the serpentine channel of the microchannel 300 is not limited to this.

[0157] Example 3

[0158] This embodiment provides another method for preparing the monolithic integrated gas chromatography chip structure. The difference from the second embodiment is that in the second embodiment, the silicon substrate is bonded to the lower cover plate before the upper cover plate is bonded, while in the third embodiment, the silicon substrate is bonded to the upper cover plate first and then the lower cover plate is bonded. The structural diagram of the gas chromatography chip in this embodiment is based on Figure 1 The dotted line MNL in FIG is a cross-sectional view of the path.

[0159] See Figure 15 and Figure 5 , performing step S3 - 1 , providing a silicon substrate 200 , wherein the silicon substrate 200 has a first surface and a second surface opposite to each other, and forming a first mask layer 210 on the first surface of the silicon substrate 200 .

[0160] The formation of the first mask layer 210 is the same as that of the second embodiment, and will not be repeated here.

[0161] See Figure 15 、 Figure 6 and Figure 7 , perform step S3 - 2 to form a fourth groove 223 on the first surface of the silicon substrate 200 , and form a first groove 221 , a second groove 222 , and a third groove 224 on the second surface of the silicon substrate 200 .

[0162] Specifically, the preparation process of the first groove 221 to the fourth groove 223 is the same as that of the second embodiment, and will not be repeated here.

[0163] As an example, a vertical projection of the fourth groove 223 covers the third groove 224 , and the first groove 221 and the second groove 222 are located on both sides of the third groove 224 .

[0164] Specifically, the fourth groove 223 provides space and position for the subsequent placement of the third bias electrode 523; the first groove 221 and the second groove 222 provide space and position for the subsequent placement of the first bias electrode 521 and the second bias electrode 522 respectively; the third groove 224 provides space and position for the subsequent placement of the collecting electrode 524.

[0165] Furthermore, by positioning the first groove 221 to the fourth groove 223, the spatial design of the subsequent 3D bias electrode is achieved, thereby providing a stable electric potential for the ion movement, guiding the ion movement direction, enhancing the electric field strength, and thus improving the ion collection efficiency. In other embodiments, the positional relationship between the first groove 221, the second groove 222, the third groove 224, and the fourth groove 223 is not limited to this.

[0166] See Figure 15 and Figure 16 , perform step S3 - 3 , provide an upper cover plate 100 , and form the third bias electrode 523 on the upper cover plate 100 .

[0167] Specifically, the upper cover 100 protects the internal structure from the influence of the external environment (such as humidity and dust), and provides mechanical support for the subsequent detection cavity 500 and electrodes; in addition, by providing a spatial position for installing the third bias electrode 523, electrical control of the detection process can be achieved.

[0168] As an example, the metal material used for the third bias electrode 523 includes one of Au and Pt. The third bias electrode 523 employs a thin-layer structure, such as a thin-film electrode, which increases the specific surface area and improves ion adsorption and transmission efficiency. Furthermore, the thin-layer structure reduces the ion transmission path and improves the response time of the detection system. Of course, the material of the third bias electrode 523 is not limited to this.

[0169] Furthermore, the third bias electrode 523 is formed by forming a metal electrode layer 525 on the surface of the upper cover plate 100 using a PVD process, then forming a third mask layer 620 on the surface of the metal electrode layer 525 using a CVD process, and then performing an etching process. The third bias electrode 523 protects the electrode during the subsequent etching of the metal electrode layer 525. In this embodiment, silicon oxide is formed using a PECVD process, and the metal electrode layer 525 is subsequently etched using a dry etching process to form the third bias electrode 523.

[0170] See Figure 15 and Figure 17 , executing step S3 - 4 , bonding the first surface of the silicon substrate 200 to the upper cover 100 , and the third bias electrode 523 corresponds to the fourth groove 223 .

[0171] Specifically, the first surface of the silicon substrate 200 is bonded to the upper cover plate 100 to form a partial structure. The upper cover plate 100 includes one of a glass cover plate, a ceramic cover plate, and a silicon cover plate. In this embodiment, the upper cover plate 100 is a glass cover plate.

[0172] As an example, the bonding method includes one of anodic bonding, fusion bonding, eutectic bonding or low temperature bonding.

[0173] Specifically, anodic bonding is used with the assistance of an electric field to bond glass to silicon at 300-450°C, which has the advantages of high bonding strength, good sealing and low temperature; melt bonding uses high temperature (800-1100°C) to diffuse and bond surface atoms, with high bonding strength and good thermal stability, but has high surface requirements and high temperature; eutectic bonding uses eutectic metal (such as Au-Si) to melt at around 430°C to form a bond, which has the characteristics of low-temperature bonding, planarization and high conductivity; when selecting a bonding method, it is necessary to comprehensively consider factors such as material compatibility, bonding temperature, bonding strength, process complexity and cost to meet specific application requirements. In this embodiment, the bonding method uses anodic bonding to achieve silicon glass bonding between glass and the upper cover plate 100.

[0174] It is worth noting that during the bonding process between the first surface of the silicon substrate 200 and the upper cover plate 100, the third mask layer 620 above the film layer of the third bias electrode 523 remains above the film layer of the third bias electrode 523, thereby further protecting the electrode during the subsequent etching process to form the groove.

[0175] See Figure 15 and Figure 18 , execute step S3-5, pattern the silicon substrate 200, and prepare micro grooves 330, carrier gas grooves and detection grooves 540 on the silicon substrate 200; the micro grooves 330, the carrier gas grooves and the detection grooves 540 penetrate the silicon substrate 200 and extend to the surface of the lower cover 600; the micro grooves 330 have a first port 310 and a first outlet end 320 arranged oppositely, and the first outlet end 320 of the micro groove 330 is connected to the detection groove 540; the carrier gas groove has a second port 410 and a second outlet end 420 arranged oppositely; the second outlet end 420 of the carrier gas groove is connected to the detection chamber 500; the collecting electrode 524, the first bias electrode 521 and the second bias electrode 522 are all located in the detection groove 540.

[0176] Specifically, the silicon substrate 200 is patterned, and dry etching is used to form the microgrooves 330, the carrier gas grooves, and the detection grooves 540. The third bias electrode 523 is located in the detection groove 540. It should be noted that the first groove 221, the second groove 222, and the third groove 224 in the figure are not completely etched to form the detection cavity 500. Parts of the first groove 221, the second groove 222, and the third groove 224 are used for the leads and lead pads of the first bias electrode 521, the second bias electrode 522, and the collecting electrode 524, respectively, and are not shown in the figure.

[0177] As an example, the micro grooves 330 are distributed in a serpentine or spiral shape, and the cross section of the micro grooves 330 includes a rectangle. The specific location and size of the micro grooves 330 are the same as those in the second embodiment, and will not be repeated here.

[0178] See Figure 15 and Figure 19 , perform step S3 - 6 , provide an upper cover plate 100 , and form the first bias electrode 521 , the second bias electrode 522 and the collecting electrode 524 on the lower cover plate 600 .

[0179] As an example, the metal material used for the first bias electrode 521, the second bias electrode 522, and the collecting electrode 524 includes one of Au and Pt. The thin-layer structure of thin-film electrodes can increase the specific surface area and improve the adsorption and transmission efficiency of ions. Furthermore, the thin-layer structure can reduce the ion transmission path and improve the response time of the detection system. Of course, the materials used for the first bias electrode 521, the second bias electrode 522, and the collecting electrode 524 are not limited to these.

[0180] Furthermore, the process of forming the first bias electrode 521 , the second bias electrode 522 and the collecting electrode 524 is the same as the preparation method of the third bias electrode 523 , which will not be described in detail here.

[0181] See Figure 15 and Figure 13 , execute step S3-7, bond the second surface of the silicon substrate 200 to the lower cover 600, and cover the micro groove 330, the carrier gas groove and the detection groove 540 with the lower cover 600 to form a sealed micro channel 300, a carrier gas channel 400 and a detection cavity 500.

[0182] Specifically, the first surface of the silicon substrate is bonded to the upper cover plate 100 to ensure that the micro groove 330, the carrier gas groove and the detection groove 540 are completely covered by the upper cover plate 100, thereby forming a sealed micro channel 300, the carrier gas channel 400 and the detection cavity 500, thereby realizing the functions of fluid transmission, gas transmission and signal detection.

[0183] Furthermore, the third bias electrode 523 is located in the detection cavity 500 and above the collecting electrode 524. Together with the first bias electrode 521 and the second bias electrode 522, they surround the collecting electrode 524 to form a 3D bias electrode, which stabilizes the movement direction of ions, enhances the electric field strength, and improves the ion collection efficiency and detection sensitivity.

[0184] Furthermore, the present invention constructs a sandwich structure of an upper cover plate-silicon substrate-lower cover plate, integrating the detection device with the microchannel separation device, that is, the microchannel, the carrier gas channel and the detection cavity are prepared on the same silicon substrate 200, which simplifies the process steps, improves the test efficiency, and optimizes the detection performance.

[0185] As an example, the length of the microchannel 300 ranges from 1 to 3 m, and the width of the first outlet end 320 of the microchannel 300 ranges from 100 to 500 μm.

[0186] As an example, the ratio of the width of the second outlet end 420 of the carrier gas channel 400 to the width of the first outlet end 320 of the microchannel 300 is in a range of 0.1 to 0.14.

[0187] As an example, the detection chamber 500 also includes an excitation chamber, a collection chamber 520 and a third port 530; the excitation chamber 510 is provided with an excitation electrode 511; the collection chamber 520 is connected to the first outlet end 320 of the microchannel 300 to collect the target gas, and the collection chamber 520 is connected to the third port 530 to discharge the exhaust gas.

[0188] As an example, the microchannel 300 is distributed in a serpentine structure, the first port 310 and the second outlet 420 of the microchannel 300 are located on both sides of the serpentine channel, and the corners of the serpentine structure ends are flush with the first outlet 320 of the microchannel 300.

[0189] As an example, the carrier gas channel 400 is parallel to the serpentine structure of the microchannel 300 .

[0190] The structure, position and size design of the microchannel 300 and the detection cavity 500 are the same as those in the second embodiment and will not be described in detail here.

[0191] The present invention constructs a sandwich structure of an upper cover plate, a silicon substrate, and a lower cover plate, and integrates a detection device with a separation device, that is, the microchannel 300, the carrier gas channel 400, and the detection cavity 500 are prepared on the same silicon substrate 200, which simplifies the process steps, improves the test efficiency, and optimizes the detection performance.

[0192] In summary, the present invention provides a gas chromatography chip structure and a preparation method thereof, which realizes the three-dimensional integration of microchannels, carrier gas channels and detection cavities by setting serpentine or spiral microchannels, carrier gas channels and detection cavities that penetrate the silicon substrate on the silicon substrate, and adopts bonding upper and lower cover plates to seal to form a complete flow path of sandwich structure, thereby realizing the three-dimensional integration of microchannels, carrier gas channels and detection cavities, thereby eliminating the connecting pipes of discrete devices, reducing dead volume and cold spots, and shortening response time; by setting collecting electrodes and 3D bias electrodes in the detection cavity, optimizing the electrode layout and improving the ion collection efficiency; by optimizing the shape and width design of the carrier gas channel and the microchannel to match the gas flow of the microchannel and the carrier gas channel, stabilizing the plasma, reducing the detection limit, and realizing the rapid separation and detection of light hydrocarbons. Therefore, the present invention significantly improves the detection sensitivity and overall stability, and realizes efficient gas detection. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0193] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A gas chromatography chip structure, characterized in that: include: A silicon substrate having a first surface and a second surface arranged opposite to each other; the silicon substrate including a microchannel, a carrier gas channel, and a detection cavity; the microchannel, the carrier gas channel, and the detection cavity extending through the silicon substrate; the microchannel having a first port and a first outlet arranged opposite to each other, the first outlet of the microchannel communicating with the detection cavity; the carrier gas channel having a second port and a second outlet arranged opposite to each other, the second outlet of the carrier gas channel communicating with the detection cavity; an upper cover plate, the upper cover plate having a first surface and a second surface disposed opposite to each other, the second surface of the upper cover plate being in contact with the first surface of the silicon substrate, the second surface of the upper cover plate being provided with a third bias electrode; and the third bias electrode being located correspondingly in the detection cavity; A lower cover plate, wherein the lower cover plate has a first surface and a second surface arranged opposite to each other, the first surface of the lower cover plate contacts the second surface of the silicon substrate, and the first surface of the lower cover plate is provided with a collecting electrode, a first bias electrode, and a second bias electrode; the collecting electrode, the first bias electrode, and the second bias electrode are all correspondingly located in the detection cavity.

2. The gas chromatography chip structure according to claim 1, characterized in that: The microchannel is distributed in a serpentine structure or a spiral structure, and the cross section of the microchannel includes a rectangle; the length of the microchannel ranges from 1 to 3 m, and the width of the microchannel ranges from 100 to 500 μm; the ratio of the width of the carrier gas channel to the width of the microchannel is 0.1 to 0.

14.

3. The gas chromatography chip structure according to claim 2, characterized in that: The microchannel is distributed in a serpentine structure, the first port and the first outlet of the microchannel are located on both sides of the serpentine structure, and the corners at the ends of the serpentine structure are flush with the first outlet of the microchannel.

4. The gas chromatography chip structure according to claim 1, characterized in that: The detection cavity also includes an excitation cavity, a collection cavity and a third port; the excitation cavity is provided with an excitation electrode; the collection cavity is connected to the first outlet end of the microchannel to collect target gas, and the collection cavity is connected to the third port to discharge exhaust gas.

5. The gas chromatography chip structure according to claim 1, characterized in that: The vertical projection of the third bias electrode covers the collecting electrode, and the first bias electrode and the second bias electrode are located on both sides of the collecting electrode.

6. A method for preparing a gas chromatography chip structure, characterized in that: The following steps are involved: Providing a silicon substrate having a first surface and a second surface opposite to each other, and forming a first mask layer on the first surface of the silicon substrate; forming a fourth groove on the first surface of the silicon substrate, forming a first groove, a second groove, and a third groove on the second surface of the silicon substrate, and removing the first mask layer; Providing a lower cover plate, forming a collecting electrode, a first bias electrode and a second bias electrode on the lower cover plate; Bonding the second surface of the silicon substrate to the lower cover plate, the collecting electrode is correspondingly located in the third groove, the first bias electrode is correspondingly located in the first groove, and the second bias electrode is correspondingly located in the second groove; Patterning the silicon substrate to prepare micro grooves, gas carrier grooves and detection grooves on the silicon substrate; The micro grooves, the gas carrier grooves and the detection grooves extend through the silicon substrate to the surface of the lower cover plate; The microgroove has a first port and a first outlet end opposite to each other, the first outlet end of the microgroove is connected to the detection groove; the carrier gas groove has a second port and a second outlet end opposite to each other; the second outlet end of the carrier gas groove is connected to the detection cavity; the collecting electrode, the first bias electrode and the second bias electrode are all located in the detection groove; providing an upper cover plate, and forming a third bias electrode on the upper cover plate; The first surface of the silicon substrate is bonded to the upper cover plate, and the upper cover plate covers the micro groove, the carrier gas groove and the detection groove to form a sealed micro groove, a carrier gas channel and a detection cavity.

7. A method for preparing a gas chromatography chip structure, characterized in that: The following steps are involved: Providing a silicon substrate having a first surface and a second surface opposite to each other, and forming a first mask layer on the first surface of the silicon substrate; forming a fourth groove on the first surface of the silicon substrate, forming a first groove, a second groove, and a third groove on the second surface of the silicon substrate, and removing the first mask layer; providing an upper cover plate, and forming a third bias electrode on the upper cover plate; Bonding the first surface of the silicon substrate to the upper cover plate, wherein the third bias electrode corresponds to the fourth groove; Patterning the silicon substrate to prepare micro grooves, gas carrier grooves, and detection grooves on the silicon substrate; The micro grooves, the gas carrier grooves and the detection grooves extend through the silicon substrate to the surface of the upper cover plate; The micro-groove has a first port and a first outlet end opposite to each other, and the first outlet end of the micro-groove is connected to the detection groove; the carrier gas groove has a second port and a second outlet end opposite to each other; the second outlet end of the carrier gas groove is connected to the detection cavity; the third bias electrode is located in the detection groove; Providing a lower cover plate, forming a collecting electrode, a first bias electrode, and a second bias electrode on the lower cover plate, wherein the collecting electrode, the first bias electrode, and the second bias electrode are all located in the detection groove; The second surface of the silicon substrate is bonded to the lower cover plate, and the micro groove, the carrier gas groove and the detection groove are covered by the lower cover plate to form a sealed micro channel, a carrier gas channel and a detection cavity.

8. The method for preparing a gas chromatography chip structure according to claim 6 or 7, characterized in that: A vertical projection of the fourth groove covers the third groove, and the first groove and the second groove are located on both sides of the third groove.

9. The method for preparing a gas chromatography chip structure according to claim 6 or 7, characterized in that: The micro groove, the gas carrier groove and the detection groove are formed by dry etching.

10. The method for preparing a gas chromatography chip structure according to claim 6 or 7, characterized in that: The bonding method of the silicon substrate, the upper cover plate and the lower cover plate includes one of anodic bonding, fusion bonding, eutectic bonding or low temperature bonding.

Images