阅读说明：本技术 一种可用空气作载气的微型气相色谱柱及其制作方法 (Miniature gas chromatographic column capable of using air as carrier gas and its making method ) 是由 王海容 石路嘉 王久洪 吴欣雨 韩宝庆 王大祚 陈家洛 于 2021-06-11 设计创作，主要内容包括：本发明公开了一种可用空气作载气的微型气相色谱柱及其制作方法,包括在硅片上光刻剥离形成铝掩膜层；通过刻蚀形成带有微立柱阵列的色谱柱微流道；酸溶液浸泡硅片,去除掩膜并与硼硅玻璃键合；在硅片背面溅射钛与铂作为测温电阻、加热丝与电极；溅射金作为电极引脚；毛细管连接微型气相色谱柱两端口；在色谱柱微流道内构筑介孔二氧化硅微球,静态涂覆方式涂覆离子液体固定相。色谱柱内介孔结构极大增加了固定相的涂覆面积,在有限色谱柱长度内提高分离能力,对氧气有很好的耐受性,保证微色谱柱在高温有氧环境下的高可靠性、高稳定性和高柱效,能够直接运用空气作载气,为VOCs检测系统提供一种优良的微色谱柱。(The invention discloses a micro gas chromatographic column using air as carrier gas and a manufacturing method thereof, comprising the steps of photoetching and stripping on a silicon wafer to form an aluminum mask layer; forming a chromatographic column micro-channel with a micro-column array by etching; soaking the silicon wafer in an acid solution, removing the mask and bonding the silicon wafer with borosilicate glass; sputtering titanium and platinum on the back of the silicon wafer to be used as a temperature measuring resistor, a heating wire and an electrode; sputtering gold as an electrode pin; the capillary tube is connected with two ports of the micro gas chromatographic column; mesoporous silica microspheres are constructed in a micro-channel of a chromatographic column, and an ionic liquid stationary phase is coated in a static coating mode. The mesoporous structure in the chromatographic column greatly increases the coating area of the stationary phase, improves the separation capacity in the limited length of the chromatographic column, has good tolerance to oxygen, ensures high reliability, high stability and high column efficiency of the micro-chromatographic column in a high-temperature aerobic environment, can directly use air as carrier gas, and provides an excellent micro-chromatographic column for a VOCs detection system.)

1. A method for manufacturing a micro gas chromatographic column using air as carrier gas is characterized by comprising the following steps:

photoetching a silicon wafer, and stripping to form an aluminum mask layer; forming a chromatographic column micro-channel with a micro-column array by a deep reactive ion etching method;

soaking a silicon wafer for etching a micro-channel of the chromatographic column by using an acid mixed solution, removing a mask and bonding the mask with borosilicate glass;

sputtering titanium and platinum on the back of the silicon wafer as a temperature measuring resistor and a heating wire by using an alignment method, a magnetron sputtering method and an ultrasonic stripping method; sputtering gold as an electrode pin;

scribing, namely connecting the capillary tube to two ports of the micro gas chromatographic column by gluing;

constructing mesoporous silica microspheres in a chromatographic column micro-channel to form a fixed phase supporting layer;

and coating an ionic liquid stationary phase in a static coating mode to finish the manufacture of the micro gas chromatographic column.

2. The method of claim 1, wherein the micro-channels are formed by deep reactive ion etching, and the micro-column arrays are regularly arranged in the micro-channels, and the cross-section of the columns is circular or square.

3. The method of claim 1, wherein the volume ratio of concentrated sulfuric acid: water: a 60 ℃ mixed solution of nitric acid 16:4:1 and concentrated sulfuric acid in volume ratio: and soaking the silicon chip after cleaning and etching the micro-channel of the chromatographic column by using the mixed solution of hydrogen peroxide and hydrogen peroxide in a ratio of 3: 1.

4. The method of claim 1, wherein the bonding voltage is 800V, the temperature is 360 ℃, and the pressure is 153 kPa.

5. The method of claim 1, wherein the step of constructing mesoporous silica microspheres in the microchannel of the chromatography column comprises:

61) according to the mass ratio (1.5-2.0): (1500-;

62) then according to the volume ratio (1-9): (1-4) dropwise adding strong ammonia water and template agent ethyl acetate into the template agent aqueous solution;

63) increasing the rotating speed, dropwise adding a silicon oxide precursor ethyl orthosilicate into the mixed solution, adjusting the rotating speed to an initial value, and adding ultra-pure water;

64) centrifuging the suspension after stirring at constant temperature, taking out the solid part for multiple times of cleaning, drying in an oven, treating the solid product in a muffle furnace, and removing the template agent to obtain the ordered mesoporous silica microspheres;

65) the mesoporous silica microspheres are prepared into an ethanol solution and are coated on the inner wall of a chromatographic column micro-channel in a static coating mode under a constant temperature environment.

6. The method as claimed in claim 5, wherein the rotation speed is increased to 800-1000 r-min^-1And 0.75ml of silicon oxide precursor ethyl orthosilicate is dripped into the mixed solution, the rotating speed is adjusted to the initial value, and 50-60ml of water is added.

7. The method for manufacturing the micro gas chromatographic column capable of using the air as the carrier gas according to claim 5, wherein the mixed solution of dilute hydrochloric acid, ammonia water, hydrogen peroxide and deionized water is used for respectively carrying out acidification and roughening treatment on the inner wall, and the mass concentration of the hydrogen peroxide and the strong ammonia water is not more than 2%; under the constant temperature environment of 75 ℃, mesoporous silica microsphere ethanol solution prepared to be 0.8-2mg/ml is used as coating liquid, and mesoporous silica microspheres are coated on the inner wall of a chromatographic column micro-channel in a static coating mode.

8. The method for manufacturing a micro gas chromatography column using air as a carrier gas in accordance with claim 1, wherein the step of coating the ionic liquid stationary phase by a static coating method comprises the following steps:

71) before coating, the inner wall is inertized by methylene dichloride solution of octamethylcyclotetrasiloxane at the temperature of 200-350 ℃;

72) preparing a stationary phase solution, and preparing the stationary phase solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

73) and introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours in sequence for drying and aging, thereby completing the manufacture of the high-resolution and high-reliability micro gas chromatographic column.

9. The method of claim 8, wherein the stationary phase solution is a dichloromethane solution with a concentration of trihexyl (tetradecyl) phosphinobis (trifluoromethylsulfonyl) amine or methyltri-n-octylammonium (bistrifluoromethylsulfonyl) imide of 8-16 mg/ml.

10. A micro gas chromatography column capable of using air as a carrier gas, prepared based on the method of any one of claims 1 to 9, comprising a silicon wafer, borosilicate glass, a titanium conductive material layer, a platinum conductive material layer and a gold electrode pin; the borosilicate glass is bonded on the upper layer of the silicon chip, the silicon dioxide layer is positioned on the back surface of the silicon chip, and the titanium conductive material layer, the platinum conductive material layer and the gold electrode pin are sequentially arranged below the silicon dioxide layer;

a chromatographic column micro-channel distributed in a snake shape is etched in a silicon chip, a micro-column array is arranged in the chromatographic column micro-channel, and mesoporous silica microspheres and an inner wall ionic liquid stationary phase are distributed in the micro-column array.

Technical Field

The invention relates to the technical field of chromatographic analysis and the field of micro-electromechanical systems, in particular to a high-resolution and high-reliability micro gas chromatographic column which can use air as carrier gas and a manufacturing method thereof.

Background

Gas chromatography is a highly efficient method for separating and detecting mixtures. The chromatographic column used by the traditional gas chromatography technology is a packed column or a fused silica capillary column, and the column is long, large in volume and long in separation time, so that the chromatographic system has the problems of large volume, slow analysis and high power consumption, and is difficult to apply to analysis of field tests such as respiratory diagnosis, environmental detection and the like.

Miniaturization of the gas chromatograph can reduce power consumption and improve portability, making it suitable for field testing applications. The micro-channel with a specific structure is processed on the silicon chip by adopting the MEMS technology, the chromatographic column with a large-diameter winding ring is changed into a planar structure, and the planar structure is integrated with a micro-heater to replace a traditional column oven, so that the volume and the power consumption of the chromatograph are greatly reduced. However, the existing micro chromatographic column has small column length and low column capacity, and is generally difficult to obtain the high separation capacity of the traditional fused quartz capillary tube with the length of dozens of meters; the chromatographic column stationary phase material works according to the principle of similar phase and intermiscibility, and when the polarity difference of components to be separated is large, the traditional single-polarity stationary phase cannot meet the separation requirement; in addition, most gas chromatography stationary phase materials including two main stationary phases of polyethylene glycol and polysiloxane have poor tolerance to oxygen and moisture, and oxygen, moisture and other impurities in carrier gas can cause oxidation and loss of the stationary phase and change of the thickness of the stationary phase film. Therefore, the conventional gas chromatograph must be equipped with a high-purity grade gas cylinder such as nitrogen/hydrogen/helium gas to provide carrier gas to ensure stable column efficiency, which greatly limits the miniaturization of the chromatograph.

Therefore, in the field detection application occasion with complicated gas components, the invention of a high-stability and high-performance micro chromatographic column is urgently needed to solve the problems of insufficient separation performance, poor stability, high-purity carrier gas requirement and the like of the existing micro chromatographic technology, and lays a solid foundation for the field application Volatile Organic Compounds (VOCs) detector which has fast integrated response, ultra-low limit, high precision and easy portability in the future.

Disclosure of Invention

Aiming at the problems of insufficient separation performance, poor stability, high-purity carrier gas requirement and the like of the existing micro-chromatography technology, the invention aims to provide a micro-chromatography column which takes air as the carrier gas (no carrier gas cylinder is required to be carried additionally), has high stability and high column efficiency, a fixed phase support body on the inner surface of the chromatography column provides a rough surface, the mesoporous structure of the micro-chromatography column greatly increases the coating area of the fixed phase, and the separation capacity is improved in the limited length of the chromatography column. The chromatographic column of the ionic liquid stationary phase has good tolerance to oxygen, can ensure the high reliability of the micro-chromatographic column in a high-temperature aerobic environment, and provides a key part of the micro-chromatographic column for a VOCs detection system which has fast response, ultra-low limit, high precision and easy portability.

The invention is realized by the following technical scheme.

A method for manufacturing a micro gas chromatographic column using air as carrier gas comprises the following steps:

photoetching a silicon wafer, and stripping to form an aluminum mask layer; forming a chromatographic column micro-channel with a micro-column array by a deep reactive ion etching method;

soaking a silicon wafer for etching a micro-channel of the chromatographic column by using an acid mixed solution, removing a mask and bonding the mask with borosilicate glass;

sputtering titanium and platinum on the back of the silicon wafer as a temperature measuring resistor, a heating wire and an electrode by an alignment method, a magnetron sputtering method and an ultrasonic stripping method; sputtering gold as an electrode pin;

scribing, namely connecting the adhesive capillary tube to two ports of the micro gas chromatographic column;

constructing mesoporous silica microspheres in a chromatographic column micro-channel to form a fixed phase supporting layer;

and coating an ionic liquid stationary phase in a static coating mode to finish the manufacture of the micro gas chromatographic column.

With respect to the above technical solutions, the present invention has a further preferable solution:

preferably, a chromatographic column micro-channel is formed by a deep reactive ion etching method, a micro-column array is regularly distributed in the chromatographic column micro-channel, and the cross section of each column is circular.

Preferably, concentrated sulfuric acid with the volume ratio of 60 ℃ is respectively used: water: the volume ratio of the mixed solution of nitric acid 16:4:1 to concentrated sulfuric acid: and soaking the silicon chip after cleaning and etching the micro-channel of the chromatographic column by using the mixed solution of hydrogen peroxide and hydrogen peroxide in a ratio of 3: 1.

Preferably, the bonding voltage is 800V, the temperature is 360 ℃ and the pressure is 153 kPa.

Preferably, the construction of the mesoporous silica microspheres in the micro-channel of the chromatographic column comprises:

61) according to the mass ratio (1.5-2.0): (1500-;

62) then according to the volume ratio (1-9): (1-4) dropwise adding strong ammonia water and template agent ethyl acetate into the template agent aqueous solution;

63) increasing the rotating speed, dropwise adding a silicon oxide precursor ethyl orthosilicate into the mixed solution, adjusting the rotating speed to the initial value, and adding water;

64) centrifuging the suspension after stirring at constant temperature, taking out the solid part for multiple times of cleaning, drying in an oven, treating the solid product in a muffle furnace, and removing the template agent to obtain the ordered mesoporous silica microspheres;

65) the mesoporous silica microspheres are prepared into an ethanol solution and are coated on the inner wall of a chromatographic column micro-channel in a static coating mode under a constant temperature environment.

Preferably, the rotating speed is increased to 800-^-1And 0.75ml of silicon oxide precursor ethyl orthosilicate is dripped into the mixed solution, the rotating speed is adjusted to the initial value, and 50-60ml of water is added.

Preferably, the inner wall is respectively acidified and roughened by using a mixed solution of dilute hydrochloric acid, ammonia water, hydrogen peroxide and deionized water, and the mass concentration of the hydrogen peroxide and the concentrated ammonia water is not more than 2%; coating the ethanol solution of the mesoporous silica microspheres prepared to be 0.8-2mg/ml on the inner wall of the micro-channel of the chromatographic column in a constant temperature environment of 75 ℃.

Preferably, the ionic liquid stationary phase is coated in a static coating mode, and the method comprises the following steps:

71) before coating, the inner wall is inertized by methylene dichloride solution of octamethylcyclotetrasiloxane at the temperature of 200-350 ℃;

72) preparing a coating solution, and preparing the coating solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

73) and introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours in sequence for drying and aging, thereby completing the manufacture of the high-resolution and high-reliability micro gas chromatographic column.

Preferably, the stationary phase solution is a dichloromethane solution with a concentration of trihexyl (tetradecyl) phosphinobis (trifluoromethylsulfonyl) amide or methyltri-n-octylammonium (bistrifluoromethylsulfonyl) imide of 8-16 mg/ml.

The invention further provides the micro gas chromatographic column which is prepared by the method and can use air as carrier gas, comprising a silicon chip, borosilicate glass, a titanium conductive material layer, a platinum conductive material layer and a gold electrode pin; the borosilicate glass is bonded on the upper layer of the silicon chip, the silicon dioxide layer is positioned on the back surface of the silicon chip, and the titanium conductive material layer, the platinum conductive material layer and the gold electrode pin are sequentially arranged below the silicon dioxide layer.

A chromatographic column micro-channel distributed in a snake shape is etched in a silicon chip, a micro-column array is arranged in the chromatographic column micro-channel, and mesoporous silica microspheres and an inner wall ionic liquid stationary phase are distributed in the micro-column array.

Due to the adoption of the technical scheme, the invention has the following beneficial effects:

1) super large ratio tableArea of mesoporous silica microspheres (greater than 1000 m)²The/g) is attached to a micro chromatographic column to form a rough surface as a fixed phase support body, the surface area of the inner wall of the column is increased through a mesoporous structure, the opportunity of action of gas and a fixed phase is improved, and the difference of different gas separation coefficients is amplified.

2) Compared with the most commonly used polyethylene glycol and polysiloxane stationary phases, the ionic liquid stationary phase has higher high temperature resistance and better thermal stability, can keep stable in a high-temperature environment with both moisture and oxygen, and can also stably work for a long time in a high-temperature environment with air as carrier gas.

3) When VOCs components with large polarity difference are separated, compared with a traditional single-polarity stationary phase, the amphoteric ionic liquid stationary phase has a better separation effect.

The ionic liquid micro chromatographic column taking the mesoporous silica microspheres as the stationary phase support has the advantages of small volume, low power consumption, easy integration, high resolution, capability of taking air as carrier gas and the like.

The column array is arranged in the micro chromatographic column to form a semi-filling structure, and a layer of mesoporous silica microspheres is added on the inner wall of the chromatographic column in a static coating mode to serve as a supporting layer of a stationary phase, so that the roughness of the inner wall is increased on the one hand by the microsphere layer, and the ionic liquid stationary phase is convenient to attach; on the other hand, the mesoporous silica microsphere layer has a high specific surface area, and the coating surface area can be increased by coating the stationary phase on the mesoporous silica microsphere layer, so that the gas and the stationary phase have more action opportunities in the separation process.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention:

FIGS. 1(a) -1 (g) show schematic diagrams of the preparative steps of the micro-chromatography column according to the invention;

FIG. 2 is a schematic diagram of a micro-chromatographic column using mesoporous silica microspheres to modify the inner surface of the column and ionic liquid as the stationary phase in example 1 of the present invention;

FIGS. 3(a) and 3(b) are SEM images of a cross section (a) and a plan view (b) of a flow channel surface-coated mesoporous silica microsphere comprising regularly arranged microcolumns prepared in the present invention;

FIGS. 4(a) -4 (d) are scanning electron micrographs and transmission electron micrographs of mesoporous silica microspheres employed in the present invention;

fig. 5(a) and 5(b) show that in example 1 of the present invention, the inner surface of the column is modified with mesoporous silica microspheres, and the micro-chromatographic column using ionic liquid as a stationary phase is separated from the micro-chromatographic column using the most commonly used polydimethylsiloxane as a stationary phase. Chromatographic peak: a. benzene, b, toluene, c, o-xylene (containing isomer impurities), d, 1,3, 5-trimethylbenzene.

FIGS. 6(a) and 6(b) show the results of example 2, in which dry air (29% O) was used₂+71％N₂) After flowing through a micro gas chromatographic column for a certain time at the temperature of 140 ℃, the inner surfaces of a 1m polydimethylsiloxane fixed phase micro gas chromatographic column (a) and a 1m mesoporous silica microsphere modified column, and a micro gas chromatographic column (b) taking ionic liquid as a fixed phase separates peak patterns of pentane, undecane, dodecane, tridecane and tetradecane.

FIG. 7 shows that in example 3, the inner surface of the column is modified with mesoporous silica microspheres at 3m, and the nonpolar n-alkane compound is separated by a micro gas chromatography column using ionic liquid as a stationary phase. Chromatographic peak: a. pentane, b, hexane, c, heptane, d, octane, e, nonane, f, decane, g, undecane, h, dodecane, i, tridecane, j, tetradecane.

Fig. 8 shows that in example 3, the inner surface of the column is modified with mesoporous silica microspheres, and a 3m micro gas chromatography column using ionic liquid as a stationary phase is used for separating strong polar alcohol compounds. Chromatographic peak: a. methanol, b, ethanol, c, propanol, d, butanol, e, pentanol, f, hexanol, g, heptanol, h, octanol.

Wherein: 1. a silicon wafer; 2. a chromatographic column microchannel; 21. a micro-pillar array; 3. a silicon dioxide layer; 4. photoresist; 5. an aluminum mask layer; 6. borosilicate glass; 7. a layer of titanium conductive material; 8. a platinum conductive material layer; 9. a gold electrode pin; 10. mesoporous silica microspheres; 11. an ionic liquid stationary phase.

Detailed Description

The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions of the present invention are provided to explain the present invention without limiting the invention thereto.

As shown in fig. 1(a) - (g) and fig. 2, the high-resolution, high-reliability micro gas chromatography column using air as carrier gas according to the embodiment of the present invention comprises: mesoporous silica microspheres 10 and an inner wall ionic liquid stationary phase 11.

The silicon chip 1 is etched with a chromatographic column micro-channel 2 distributed in a snake shape, the upper layer of the silicon chip 1 is bonded with borosilicate glass 6, the back of the silicon chip 1 is provided with a silicon dioxide layer 3, a titanium conductive material layer 7, a platinum conductive material layer 8 and a gold electrode pin 9 are sequentially arranged below the silicon dioxide layer 3, and the titanium layer can prevent a platinum heating and temperature measuring material layer from falling off from the silicon dioxide layer and enhance the platinum adhesive force. Wherein, a micro-column array 21 is arranged in the chromatographic column micro-channel 2, and mesoporous silica microspheres 10 and an inner wall ionic liquid stationary phase 11 are arranged in the micro-column array 21.

The following is a method for preparing a high-resolution, high-reliability micro gas chromatography column using air as a carrier gas according to the present invention, as shown in FIGS. 1(a) to (g), comprising the steps of:

step 1), performing photoetching on an N-type double-sided polished single-sided oxidized silicon wafer 1 with the thickness of 4 inches, 500 and 800nm as shown in FIG. 1 (a); an aluminum mask layer 5 with a thickness of 150-200nm is formed by electron beam evaporation and lift-off, as shown in FIG. 1 (b).

And 2) forming a chromatographic column micro-channel 2 by a deep reactive ion etching method by using aluminum as a mask, as shown in fig. 1 (c). The size of the micro-channel of the chromatographic column is as follows: the total length ranges from 1 to 3 m; the width is 200 um; depth 100-; the micro-column arrays are regularly arranged in the micro-flow channel of the chromatographic column, the cross section of each column is circular or square, the diameter (side length) of each column is 30 micrometers, the distance on the flow velocity section is 25-30 micrometers, and the distance from the wall surface in the direction perpendicular to the flow velocity direction is 30 micrometers.

And 3) respectively using concentrated sulfuric acid with the mass ratio of 60 ℃: water: the mass ratio of the mixed solution of nitric acid 16:4:1 to concentrated sulfuric acid: soaking the silicon chip after cleaning and etching the chromatographic column micro-channel 2 in the mixed solution of 3:1 hydrogen peroxide, and carrying out anodic bonding on the silicon chip and borosilicate glass 6 under the conditions of bonding voltage of 800V, temperature of 360 ℃ and pressure of 153kPa, as shown in fig. 1 (d).

Step 4): on the back of the silicon chip, namely the silicon dioxide surface, a titanium conductive material layer 7 with the thickness range of 20nm-50nm and a platinum conductive material layer 8 with the thickness range of 200-250nm are respectively formed as a heating wire and a temperature measuring resistor by means of alignment, magnetron sputtering and ultrasonic stripping.

Gold is then sputtered to a thickness of 100nm-200nm as electrode leads 9 for future integration with other components of the micro chromatograph, as shown in fig. 1 (e).

Step 5): scribing; two ports of the micro gas chromatographic column are respectively connected with a fused quartz capillary tube with the length of 0.1m by a high-temperature resistant industrial glue in a gluing mode.

Step 6): mesoporous silica microspheres 10 are constructed in a micro flow channel of a chromatographic column to form a stationary phase supporting layer, as shown in fig. 1 (f).

The step 6 specifically comprises the following steps:

the method for synthesizing the mesoporous silica microspheres with high specific surface area by adopting a gel sol method comprises the following steps:

6-1) the rotating speed of the magnetic stirrer is 600-^-1Then 150mg-200mg of template cetyl trimethyl ammonium bromide is dissolved in 160ml of deionized water;

6-2) then dripping 1-9ml of strong ammonia water and 1-4ml of template agent ethyl acetate into the solution of the template agent;

6-3) increasing the rotating speed to 800-^-1Dropwise adding 0.75ml of silicon oxide precursor ethyl orthosilicate into the mixed solution, adjusting the rotating speed to the initial value, and then adding 50-60ml of water;

6-4) centrifuging the suspension after stirring at a constant temperature of 24h, taking out a solid part, cleaning the solid part with ethanol for multiple times, drying the solid part in an oven at a temperature of more than 80 ℃ for more than 12h, treating the solid product in a muffle furnace at a high temperature environment at a temperature of more than 500 ℃ for more than 5h, and removing a template agent to obtain the ordered mesoporous silica microspheres, wherein scanning electron micrographs of the mesoporous silica microspheres prepared under the parameters are shown in detail in fig. 4(a) and 4(b), and transmission electron micrographs are shown in fig. 4(c) and 4 (d);

6-5) preparing the mesoporous silica microspheres into 0.8-2mg/ml ethanol solution, and coating the ethanol solution on the inner wall of the micro-channel of the chromatographic column in a static coating manner at the constant temperature of 75 ℃.

Before coating, the inner wall is respectively acidified and roughened by using a mixed solution of dilute hydrochloric acid, ammonia water, hydrogen peroxide and deionized water. In the mixed solution of ammonia water, hydrogen peroxide and deionized water, attention is paid to control the concentration of the hydrogen peroxide and the concentrated ammonia water not to exceed 2 percent, otherwise, the micro chromatographic column is excessively corroded.

Step 7): the static coating mode is to coat the ionic liquid stationary phase 11, as shown in fig. 1(g), and specifically includes the following steps:

7-1) before coating, carrying out inerting treatment on the inner wall by using a dichloromethane solution of octamethylcyclotetrasiloxane at a high temperature of 200-350 ℃; and (3) coating an ionic liquid stationary phase in a static coating mode, carrying out inerting treatment on the inner wall by using octamethylcyclotetrasiloxane before coating, removing metal impurity ions and abundant silanol groups on the inner wall and the surface of the mesoporous silica microsphere, and avoiding tailing in separation. Finally, drying and aging by high-temperature nitrogen;

7-2) preparing 8-16mg/ml dichloromethane solution of trihexyl (tetradecyl) phosphine bis (trifluoromethylsulfonyl) amide (or methyltri-n-octylammonium (bistrifluoromethylsulfonyl) imide) and preparing the dichloromethane solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

7-3) sequentially introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours for drying and aging. Thus, the manufacture of the micro gas chromatographic column with high separation degree and high reliability is completed.

The following specific examples are given to further illustrate the invention.

Example 1

Step 1), photoetching is carried out on an N-type double-sided polished single-sided oxidized silicon wafer 1 with the thickness of 4 inches and the thickness of 500nm, and an aluminum mask layer 5 with the thickness of 160nm is formed through electron beam evaporation and stripping.

And 2) forming a chromatographic column micro-channel 2 by using aluminum as a mask through a deep reactive ion etching method. The size of the micro-channel of the chromatographic column is as follows: the total length is 3 m; the width is 200 um; the depth is 250 um; the micro-column array is regularly arranged in the micro-channel of the chromatographic column, the cross section of each column is circular, the diameter of each column is 30um, the distance between the columns on the flow velocity section is 26um, and the distance between the columns and the wall surface is 29um in the direction perpendicular to the flow velocity.

And 3) respectively using concentrated sulfuric acid with the mass ratio of 60 ℃: water: the mass ratio of the mixed solution of nitric acid 16:4:1 to concentrated sulfuric acid: soaking the silicon chip after cleaning and etching the chromatographic column micro-channel 2 in a mixed solution of 3:1 hydrogen peroxide, and carrying out anodic bonding on the silicon chip and borosilicate glass 6 under the conditions that the bonding voltage is 800V, the temperature is 360 ℃, and the pressure is 153 kPa.

Step 4): on the back of the silicon chip, namely the silicon dioxide surface, a 50nm titanium conductive material layer 7 and a 200nm platinum conductive material layer 8 are respectively formed as a heating wire and a temperature measuring resistor by means of alignment, magnetron sputtering and ultrasonic stripping.

200nm of gold is then sputtered as electrode pin 9 for future integration with other components of the micro chromatograph.

Step 5): scribing: two ports of the micro gas chromatographic column are respectively connected with a fused quartz capillary tube with the length of 0.1m by a high-temperature resistant industrial glue in a gluing mode.

Step 6): mesoporous silica microspheres 10 are constructed in a micro-channel of a chromatographic column to form a fixed phase supporting layer.

The step 6 specifically comprises the following steps:

the method for synthesizing the mesoporous silica microspheres with high specific surface area by adopting a gel sol method comprises the following steps:

6-1) rotating speed of a magnetic stirrer at 700r min^-1150mg of template cetyl trimethyl ammonium bromide is dissolved in 150ml of deionized water;

6-2) then 5ml of strong ammonia water and 1.5ml of template agent ethyl acetate are taken and added into the solution of the template agent;

6-3) increasing the rotating speed to 800 r.min during continuous stirring^-1And 0.75ml of silicon oxide precursor ethyl orthosilicate is dripped into the mixed solution, and thenThe rotating speed is adjusted back to the initial value, and 56ml of water is added;

6-4) centrifuging the suspension after stirring at a constant temperature for 24 hours, taking out a solid part, cleaning the solid part with ethanol for multiple times, drying the solid part in an oven at a temperature of more than 80 ℃ for more than 12 hours, treating the solid product in a muffle furnace at a high temperature environment at a temperature of more than 500 ℃ for more than 5 hours, and removing the template agent to obtain the ordered mesoporous silica microspheres;

6-5) preparing the mesoporous silica microspheres into 0.8mg/ml ethanol solution, and coating the ethanol solution on the inner wall of the micro-channel of the chromatographic column in a static coating manner at the constant temperature of 75 ℃.

Step 7): the static coating mode for coating the ionic liquid stationary phase 11 specifically comprises the following steps:

7-1) before coating, carrying out inerting treatment on the inner wall by using a dichloromethane solution of octamethylcyclotetrasiloxane at a high temperature of 250 ℃;

7-2) preparing 8mg/ml dichloromethane solution of trihexyl (tetradecyl) phosphine bis (trifluoromethylsulfonyl) amide, and preparing the dichloromethane solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

7-3) sequentially introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours for drying and aging. Thus, the manufacture of the micro gas chromatographic column with high separation degree and high reliability is completed.

In this example 1, the separation result of the prepared micro-column for the para-benzene series is shown in fig. 5(a), the separation result of the para-benzene series of the micro-column with the same structure and using the traditional polydimethylsiloxane as the stationary phase is shown in fig. 5(b), and the chromatographic peaks: a. benzene, b, toluene, c, o-xylene (containing partial isomer impurities), d, 1,3, 5-trimethylbenzene.

The invention forms a semi-filling structure by arranging a micro-column array 21 in a chromatographic column micro-channel 2, and adds a layer of mesoporous silica microspheres 10 as a supporting layer of a stationary phase on the inner wall of the chromatographic column by a static coating mode, and figures 3(a) and 3(b) show a cross section view 3(a) and a top view 3(b) of the micro-channel surface coated mesoporous silica microspheres containing regularly arranged micro-columns prepared in the invention, and a white film is a layer of silica microspheres on the surface. On one hand, the microsphere layer increases the roughness of the inner wall, so that the ionic liquid stationary phase 11 can be conveniently attached; on the other hand, the mesoporous silica microsphere layer has a high specific surface area, and the coating surface area can be increased by coating the stationary phase on the mesoporous silica microsphere layer, so that the gas and the stationary phase have more action opportunities in the separation process.

In this embodiment 1, the high-resolution and high-reliability micro gas chromatography column using air as carrier gas has a high column efficiency, and the mixture resolution, the thermal stability of the ionic liquid stationary phase and the oxidation resistance of the column are all improved. Compare with the same structure, use traditional polydimethylsiloxane as the miniature gas chromatographic column of stationary phase, under the same separation condition, when the miniature chromatographic column of this embodiment separates the benzene series mixture of weak polarity, the resolution has showing the promotion, if: the separation degree between benzene and toluene is improved from 1.66 to 2.41, the separation degree between toluene and o-xylene is improved from 2.31 to 2.35, and the separation degree between the isomers capable of separating o-xylene and the separation degree between o-xylene toluene and trimethylbenzene is improved from 3.99 to 4.67; the theoretical plate height of each material was reduced by about 10%. In terms of thermal stability, when the working temperature is increased from 50 ℃ to 140 ℃, the baseline drift of the micro gas chromatographic column which has the same structure and takes the traditional polydimethylsiloxane as the stationary phase is about 10mv due to temperature programming, while the micro chromatographic column of the embodiment only has 4 mv. In the aspect of oxidation resistance, after dry air (29% O2+ 71% N2) flows through the chromatographic column at 135 ℃ for 6 hours, the base line of the micro gas chromatographic column which has the same structure and takes the traditional polydimethylsiloxane as the stationary phase obviously drifts and seriously influences the appearance of peaks, but the base line of the micro gas chromatographic column of the invention is still stable, and the relative standard deviation of the retention time of each component is less than 2%.

Example 2

Step 1), photoetching is carried out on an N-type double-sided polished single-sided oxidized silicon wafer 1 with the thickness of 4 inches and the thickness of 600nm, and an aluminum mask layer 5 with the thickness of 150nm is formed through electron beam evaporation and stripping.

And 2) forming a chromatographic column micro-channel 2 by using aluminum as a mask through a deep reactive ion etching method. The size of the micro-channel of the chromatographic column is as follows: the total length is 1 m; the width is 200 um; the depth is 100 um; the micro-column array is regularly arranged in the micro-channel of the chromatographic column, the cross section of each column is square, the side length is 30um, the distance on the flow velocity section is 25um, and the distance from the wall surface in the direction perpendicular to the flow velocity is 30 um.

And 3) respectively using concentrated sulfuric acid with the mass ratio of 60 ℃: water: the mass ratio of the mixed solution of nitric acid 16:4:1 to concentrated sulfuric acid: soaking the silicon chip after cleaning and etching the chromatographic column micro-channel 2 in the mixed solution of 3:1 hydrogen peroxide, and carrying out anodic bonding on the silicon chip and borosilicate glass 6 under the conditions that the bonding voltage is 800V, the temperature is 380 ℃ and the pressure is 160 kPa.

Step 4): on the back of the silicon chip, namely the silicon dioxide surface, a titanium conductive material layer 7 with the thickness of 30nm and a platinum conductive material layer 8 with the thickness of 250nm are respectively formed as a heating wire and a temperature measuring resistor by means of alignment, magnetron sputtering and ultrasonic stripping.

Gold is then sputtered to a thickness of 150nm as electrode pins 9 for future integration with other components of the micro chromatograph.

Step 5): scribing: two ports of the micro gas chromatographic column are respectively connected with a fused quartz capillary tube with the length of 0.1m by a high-temperature resistant industrial glue in a gluing mode.

Step 6): mesoporous silica microspheres 10 are constructed in a micro-channel of a chromatographic column to form a fixed phase supporting layer.

The step 6 specifically comprises the following steps:

the method for synthesizing the mesoporous silica microspheres with high specific surface area by adopting a gel sol method comprises the following steps:

6-1) rotating speed of the magnetic stirrer is 600-min^-1Next, 180mg of the template cetyl trimethylammonium bromide was dissolved in 160ml of deionized water;

6-2) then dripping 1ml of strong ammonia water and 1ml of template agent ethyl acetate into the solution of the template agent;

6-3) increasing the rotating speed to 900 r.min during continuous stirring^-10.75ml of silicon oxide precursor ethyl orthosilicate is dripped into the mixed solution, the rotating speed is adjusted to the initial value, and 50ml of water is added;

6-4) centrifuging the suspension after stirring at a constant temperature for 24 hours, taking out a solid part, cleaning the solid part with ethanol for multiple times, drying the solid part in an oven at a temperature of more than 80 ℃ for more than 12 hours, treating the solid product in a muffle furnace at a high temperature environment at a temperature of more than 500 ℃ for more than 5 hours, and removing the template agent to obtain the ordered mesoporous silica microspheres;

6-5) preparing the mesoporous silica microspheres into 2mg/ml ethanol solution, and coating the ethanol solution on the inner wall of the micro-channel of the chromatographic column in a static coating manner at the constant temperature of 75 ℃.

Step 7): the static coating mode for coating the ionic liquid stationary phase 11 specifically comprises the following steps:

7-1) before coating, carrying out inerting treatment on the inner wall by using a dichloromethane solution of octamethylcyclotetrasiloxane at the high temperature of 350 ℃;

7-2) preparing a dichloromethane solution of 16mg/ml methyltri-n-octylammonium bis (bistrifluoromethylsulfonyl) imide, and preparing the dichloromethane solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

7-3) sequentially introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours for drying and aging. Thus, the manufacture of the micro gas chromatographic column with high separation degree and high reliability is completed.

FIGS. 6(a) and 6(b) show the separation of peaks of pentane, undecane, dodecane, tridecane, tetradecane, according to the time axis, for a mixture of alkanes from 1m of a 1m polydimethylsiloxane stationary phase micro gas chromatography column of FIG. 6(a) and 1m of an ionic liquid stationary phase micro gas chromatography column of FIG. 6(b) after a certain time of flow through the columns with dry air (29% O2+ 71% N2) at 140 ℃ in example 2.

In this embodiment 2, the high-resolution and high-reliability micro gas chromatography column using air as carrier gas has a higher column efficiency, and the mixture resolution, thermal stability and oxidation resistance of the ionic liquid stationary phase of the micro gas chromatography column are improved compared with those of the micro gas chromatography column having the same structure and using the conventional polydimethylsiloxane as the stationary phase. Compare with the same structure, use traditional polydimethylsiloxane as the miniature gas chromatographic column of stationary phase, under the same separation condition, when the miniature chromatographic column of this embodiment separates the benzene series mixture of weak polarity, the resolution has showing the promotion, if: the separation degree between benzene and toluene is improved from 1.13 to 1.46, the separation degree between toluene and o-xylene is improved from 1.34 to 1.98, and the separation degree between o-xylene, toluene and trimethylbenzene is improved from 2.18 to 3.29. In terms of thermal stability, when the working temperature is increased from 40 ℃ to 120 ℃, the baseline drift of the micro gas chromatographic column which has the same structure and takes the traditional polydimethylsiloxane as the stationary phase is about 9.3mv due to temperature programming, while the micro gas chromatographic column of the embodiment only has 3.7 mv. In terms of oxidation resistance, after flowing through the column with dry air (29% O2+ 71% N2) at 140 ℃ for 42h, and using a mixture of pentane, undecane, dodecane, tridecane and tetradecane as the reagent to be separated, the baseline of the micro-gas chromatography column of the same structure and using the traditional polydimethylsiloxane as the stationary phase drifts significantly and loses the separation ability completely, while the baseline of the micro-gas chromatography column of the embodiment is still stable, and the relative standard deviation of the retention time of each component is less than 4%.

Example 3

Step 1), photoetching is carried out on an N-type double-sided polished single-sided oxidized silicon wafer 1 with the thickness of 4 inches and the thickness of 800nm, and an aluminum mask layer 5 with the thickness of 170nm is formed through electron beam evaporation and stripping.

And 2) forming a chromatographic column micro-channel 2 by using aluminum as a mask through a deep reactive ion etching method. The size of the micro-channel of the chromatographic column is as follows: the total length is 3 m; the width is 200 um; the depth is 300 um; the micro-column array is regularly arranged in the micro-channel of the chromatographic column, the cross section of each column is circular, the diameter of each column is 30um, the distance between every two columns on the flow rate section is 25um, and the distance between every two columns and the wall surface is 30um in the vertical flow rate direction.

And 3) respectively using concentrated sulfuric acid with the mass ratio of 60 ℃: water: the mass ratio of the mixed solution of nitric acid 16:4:1 to concentrated sulfuric acid: soaking the silicon chip after cleaning and etching the chromatographic column micro-channel 2 in the mixed solution of 3:1 hydrogen peroxide, and carrying out anodic bonding on the silicon chip and borosilicate glass 6 under the conditions that the bonding voltage is 800V, the temperature is 350 ℃, and the pressure is 150 kPa.

Step 4): on the back of the silicon chip, namely the silicon dioxide surface, a titanium conductive material layer 7 with the thickness of 20nm and a platinum conductive material layer 8 with the thickness of 220nm are respectively formed as a heating wire and a temperature measuring resistor by means of alignment, magnetron sputtering and ultrasonic stripping.

100nm of gold is then sputtered as electrode pin 9 for future integration with other components of the micro chromatograph.

Step 5): scribing: two ports of the micro gas chromatographic column are respectively connected with a fused quartz capillary tube with the length of 0.1m by a high-temperature resistant industrial glue in a gluing mode.

Step 6): mesoporous silica microspheres 10 are constructed in a micro-channel of a chromatographic column to form a fixed phase supporting layer.

The step 6 specifically comprises the following steps:

the method for synthesizing the mesoporous silica microspheres with high specific surface area by adopting a gel sol method comprises the following steps:

6-1) rotating speed of the magnetic stirrer at 800 r.min^-1150mg of template cetyl trimethyl ammonium bromide is dissolved in 155ml of deionized water;

6-2) then dripping 9ml of strong ammonia water and 4ml of template agent ethyl acetate into the solution of the template agent;

6-3) increasing the rotation speed to 1000 r.min during continuous stirring^-10.75ml of silicon oxide precursor ethyl orthosilicate is dripped into the mixed solution, the rotating speed is adjusted to the initial value, and 60ml of water is added;

6-4) centrifuging the suspension after stirring at a constant temperature for 24 hours, taking out a solid part, cleaning the solid part with ethanol for multiple times, drying the solid part in an oven at a temperature of more than 80 ℃ for more than 12 hours, treating the solid product in a muffle furnace at a high temperature environment at a temperature of more than 500 ℃ for more than 5 hours, and removing the template agent to obtain the ordered mesoporous silica microspheres;

6-5) preparing the mesoporous silica microspheres into 1mg/ml ethanol solution, and coating the ethanol solution on the inner wall of the micro-channel of the chromatographic column in a static coating manner at the constant temperature of 75 ℃.

Step 7): the static coating mode for coating the ionic liquid stationary phase 11 specifically comprises the following steps:

7-1) before coating, carrying out inerting treatment on the inner wall by using a dichloromethane solution of octamethylcyclotetrasiloxane at a high temperature of 200 ℃;

7-2) preparing 12mg/ml dichloromethane solution of trihexyl (tetradecyl) phosphine bis (trifluoromethylsulfonyl) amide, and preparing the dichloromethane solution on a stationary phase supporting layer in a static coating mode at the constant temperature of 40 ℃;

7-3) sequentially introducing high-temperature nitrogen gas at 100 ℃ for 1 hour and nitrogen gas at 200 ℃ for 2 hours for drying and aging. Thus, the manufacture of the micro gas chromatographic column with high separation degree and high reliability is completed.

In example 3, the separation result of the prepared micro-chromatographic column on the nonpolar n-alkane compound is shown in fig. 7, and the chromatographic peaks: a. pentane, b, hexane, c, heptane, d, octane, e, nonane, f, decane, g, undecane, h, dodecane, i, tridecane and j, tetradecane. In example 3, the separation result of the prepared micro-chromatographic column on the strongly polar alcohol compound is shown in fig. 8, and the chromatographic peaks: a. methanol, b, ethanol, c, propanol, d, butanol, e, pentanol, f, hexanol, g, heptanol, h, octanol.

In this embodiment 3, the high-resolution and high-reliability micro gas chromatography column using air as carrier gas has a high column efficiency, and the mixture resolution, the thermal stability of the ionic liquid stationary phase and the oxidation resistance of the column are improved to a certain extent. In this embodiment 3, the high-resolution and high-reliability micro gas chromatography column using air as carrier gas has a higher column efficiency, and the mixture resolution, thermal stability and oxidation resistance of the ionic liquid stationary phase of the micro gas chromatography column are improved compared with those of the micro gas chromatography column having the same structure and using the conventional polydimethylsiloxane as the stationary phase. Compare with the same structure, use traditional polydimethylsiloxane as the miniature gas chromatography column of stationary phase, under the same separation condition, when the miniature chromatographic column of this embodiment separates strong polar alcohols mixture, the resolution has showing the promotion, if: the separation degree of methanol and ethanol is improved from 0 to 0.86, the separation degree of ethanol and propanol is improved from 1.51 to 2.88, and the separation degree of propanol and butanol is improved from 3.60 to 5.10. In terms of thermal stability, when the working temperature is increased from 45 ℃ to 100 ℃, the baseline drift of the micro gas chromatographic column which has the same structure and takes the traditional polydimethylsiloxane as the stationary phase is about 8.1mv due to temperature programming, while the micro gas chromatographic column of the embodiment only has 2.9 mv. In terms of oxidation resistance, after dry air (29% O2+ 71% N2) flows through the chromatographic column at 120 ℃ for 36 hours, the baseline of the micro gas chromatographic column with the same structure and the traditional polydimethylsiloxane as the stationary phase obviously drifts seriously and completely loses the separation capability, but the baseline of the micro gas chromatographic column in the embodiment is still stable, and the relative deviation of the separation degree is less than 3%.

As mentioned above, the high-resolution and high-reliability micro gas chromatographic column which can use air as carrier gas has higher column efficiency, and uses mesoporous silica microspheres as a stationary phase support and ionic liquid as a stationary phase. The stationary phase support is attached to the micro chromatographic column to form a rough surface as the stationary phase support, and the surface area of the inner wall of the column is increased through the mesoporous structure, so that the separation degree of the mixture is further improved. The ionic liquid stationary phase has better thermal stability and oxidation resistance, and can stably work for a long time under the high-temperature environment that air is used as carrier gas.

The invention has practical progress on the existing basis of the micro gas chromatographic column, and the high-separation-degree and high-reliability micro gas chromatographic column which can use air as carrier gas and is prepared by the method has higher column efficiency and mixture separation degree than the existing micro gas chromatographic column with the same structure and the most common traditional polysiloxane fixed phase under most conditions. The thermal stability of the invention is better, the baseline drift value is reduced by at least 50% compared with the existing polysiloxane fixed phase, and the oxidation resistance is also better, under the high-temperature oxygen-containing carrier gas environment, the service life is greatly improved, under the 140 ℃ oxygen-containing carrier gas environment, the most common polydimethylsiloxane fixed phase is degraded and failed after about 12 hours, while the ionic liquid fixed phase can still keep a stable baseline after 42 hours, and the relative deviation of the retention time of each substance is not more than 4%. Therefore, the present invention has the potential to further integrate a more portable, air-borne, field application detector.

The technical solutions, advantages and the like of the present invention are described in detail with reference to the above embodiments, and it should be noted that the above embodiments are only examples of the present disclosure and are not intended to limit the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.