CN212440148U - Transmission type solid phase micro extraction micro flow control device - Google Patents

Abstract

A transmission type solid phase micro-extraction micro-fluidic device comprises a solid phase micro-extraction film, an upper micro-fluidic chip and a lower micro-fluidic chip which are bonded with the solid phase micro-extraction film, wherein the upper micro-fluidic chip and the solid phase micro-extraction film are bonded to form a closed extraction liquid flow channel; the lower micro-fluidic chip is bonded with the solid phase micro-extraction film to form a micro-extraction liquid storage tank; the outlets of the flow channels are positioned at the tips of the upper and lower microfluidic chips to form nozzles; the extraction liquid injected into the extraction liquid flow passage is used for carrying out transmission type solid phase micro-extraction on the sample through a solid phase micro-extraction film, and after the solid phase micro-extraction is carried out, a driving medium is injected into an inlet of the flow passage to drive the extraction liquid containing the target analyte to be discharged from a nozzle. The transmission type solid phase micro-extraction micro-fluidic device can realize solid phase micro-extraction and can be conveniently combined with a mass spectrometer for direct sample injection.

Description

Transmission type solid phase micro extraction micro flow control device

Technical Field

The utility model relates to a solid phase micro-extraction technology, in particular to a transmission type solid phase micro-extraction micro-fluidic device.

Background

In 1990, the concept of solid phase microextraction is firstly clearly proposed by Pawliszyn and the like, and compared with solid phase extraction, the advantages of less solvent consumption and short extraction time are kept; meanwhile, the defects of high blank background, blockage and fixation and the like are overcome. The main body of the solid phase micro-extraction device is a syringe, and the core component is quartz optical fiber coated with organic stationary phase or inorganic adsorbent. During extraction, the needle head is placed in a sample to be detected, quartz fiber is pushed out, and target components in the sample are enriched and extracted; after extraction, the fiber is pulled back to the needle head for storage; during desorption, the gas chromatographic sample inlet is directly inserted for heating desorption, and the gas chromatographic sample inlet is merged into a chromatographic column for separation and then is detected.

Qin, 2009, proposed that a folded copper mesh could be used to protect the solid phase microextraction membrane; meanwhile, the method can also inhibit the growth of microorganisms on the film due to the bactericidal action of copper ions. The method comprises 5 steps: 1. the first is the perforation of the copper mesh. Milling a large hole on the left side of the copper mesh, and milling a small hole on the right side of the copper mesh. Wherein the macropores are used for allowing target analytes to enter the membrane and taking out the membrane after extraction; the small hole can only be passed by a small screwdriver, and the small hole has the function of supporting the thin film and preventing the thin film from falling off during sampling. 2. The second is the folding of the copper mesh. The copper mesh is folded and the edges are welded by welding. Thus, a copper mesh pocket with one end open is completed. 3. And thirdly, putting the film. And (3) putting the solid phase microextraction film into a pocket, wherein the pocket is connected to the sampling rod through a screw. And the fourth step is the taking out of the film. After extraction was complete, the film was pushed out of the large hole with a small screwdriver through the small hole. 5. And fifthly, storing the film. The analyte-rich membrane needs to be protected in a clean tube sealed at both ends, which helps prevent analyte flow and prevents contamination of the analyte.

The prior art has the defects and problems that:

solid phase micro-extraction head:

1. many target analytes and solid coatings of solid phase microextraction heads adsorb strongly, and desorption can only be completed at high temperature. For polar compounds, high temperatures tend to cause degradation.

2. The solid coating capacity of the solid phase micro-extraction head is limited, so the saturation degree is low and the linear calibration range is low. Liquid coatings, however, overcome the disadvantages of solid coatings because liquid coatings are absorptive extractions. Wherein the solid phase microextraction film is often coated with a liquid.

And (3) clamping and extracting the solid-phase microextraction film by using a copper net:

1. the film is exposed and is fragile.

2. The extraction and elution are not together.

3. Interfering components may remain.

The above background disclosure is only for the purpose of assisting understanding of the inventive concepts and technical solutions of the present invention, and does not necessarily belong to the prior art of the present patent application, and should not be used for evaluating the novelty and inventive step of the present application in the case that there is no clear evidence that the above contents are disclosed at the filing date of the present patent application.

SUMMERY OF THE UTILITY MODEL

The main object of the present invention is to overcome at least one of the above technical drawbacks, and to provide a transmission type solid phase micro-extraction micro-fluidic device.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a transmission type solid phase micro-extraction micro-fluidic device comprises a solid phase micro-extraction film, an upper micro-fluidic chip and a lower micro-fluidic chip, wherein the upper surface and the lower surface of the solid phase micro-extraction film are respectively bonded with the upper micro-fluidic chip and the lower micro-fluidic chip; the lower micro-fluidic chip is provided with a liquid storage tank with an opening facing the solid phase micro-extraction film, and the liquid storage tank is formed into a micro-extraction liquid storage tank after the lower micro-fluidic chip is bonded with the solid phase micro-extraction film; the upper and lower microfluidic chips have tips bonded together, and the outlets of the flow channels are located at the tips to form nozzles at the tips.

Further, the solid phase micro-extraction film, the upper micro-fluidic chip and the lower micro-fluidic chip are made of Polydimethylsiloxane (PDMS) materials.

Furthermore, the liquid storage tank is a cavity penetrating through the upper surface and the lower surface of the lower microfluidic chip, and the microfluidic device is turned over during solid-phase microextraction, so that the lower microfluidic chip is positioned above the upper microfluidic chip.

Further, the solid phase micro-extraction film covers the whole area of the flow channel.

Further, the flow channel is an M-shaped flow channel with a winding structure at least in a region corresponding to the liquid storage tank.

Furthermore, the solid phase micro-extraction film is bonded with the upper micro-fluidic chip and the lower micro-fluidic chip through oxygen plasma bonding.

Further, the driving medium is an eluent.

The utility model discloses following beneficial effect has:

the utility model provides a transmission type solid phase micro-extraction micro-fluidic device, which comprises an upper micro-fluidic chip, a lower micro-fluidic chip and a solid phase micro-extraction film bonded between the upper micro-fluidic chip and the lower micro-fluidic chip to form a sandwich structure, wherein the upper micro-fluidic chip is provided with a flow channel, and the flow channel is formed into a closed extraction liquid flow channel after the upper micro-fluidic chip is bonded with the solid phase micro-extraction film; the lower micro-fluidic chip is provided with a liquid storage tank with an opening facing the solid phase micro-extraction film, and the liquid storage tank is formed into a micro-extraction liquid storage tank after the lower micro-fluidic chip is bonded with the solid phase micro-extraction film; and the upper and lower microfluidic chips have tips bonded together, the outlets of the flow channels being located at the tips to form nozzles at the tips; in use, a sample injected into the microextraction reservoir is in direct contact with the solid phase microextraction membrane, an extraction liquid (such as an organic solvent like ethanol) injected into the extraction liquid flow channel performs permeable solid phase microextraction on the sample (such as a complex matrix) through the solid phase microextraction membrane, the sample and the extraction liquid are completely separated, an interference component is remained in the complex matrix, and a target analyte component enters the extraction liquid through the solid phase microextraction membrane; after the solid phase microextraction is carried out, the extract containing the target analyte is driven to be discharged from the nozzle by injecting a driving medium into the inlet of the flow channel. Therefore, the utility model discloses a transmission type solid phase micro-extraction micro-fluidic device not only can realize solid phase micro-extraction, but also can use with the mass spectrograph jointly very conveniently, through right the extract liquid is executed high piezoelectricity and can be formed the electrospray, directly carries out the mass spectrograph and advances the appearance, realizes the material analysis, promptly, realizes simultaneously that the extraction obtains the target analyte that purifies and advances kind these two kinds of functions from complicated matrix sample.

In preferred scheme, the utility model discloses can also obtain further advantage, for example, the runner design is the M type, is showing the area of contact who has increased runner and solid phase micro-extraction film, can increase the extraction volume under the prerequisite that does not increase the thickness of film, improve sensitivity, improve extraction efficiency.

Drawings

Fig. 1 is a schematic exploded view of a transmission-type solid-phase microextraction microfluidic device according to an embodiment of the present invention.

Fig. 2 is a perspective structure diagram of a transmission type solid phase micro-extraction micro-fluidic device according to an embodiment of the present invention.

Fig. 3 is a schematic view of a manufacturing process of a transmission type solid-phase microextraction microfluidic device according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a silicon wafer template for manufacturing an upper microfluidic chip and a lower microfluidic chip according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of an embodiment of the present invention in which a silicon wafer template is used to fabricate an upper microfluidic chip and a lower microfluidic chip.

FIG. 6(a) is a graph showing the results of analysis of a 2ppm malachite green fish blood sample directly injected into a mass spectrometer.

Fig. 6(b) is an analysis result diagram of 2ppm malachite green fish blood sample through the transmission type microextraction micro-fluidic chip provided by the embodiment of the utility model to carry out mass spectrometer sample injection.

Detailed Description

The following describes embodiments of the present invention in detail. It should be emphasized that the following description is merely exemplary in nature and is not intended to limit the scope of the invention or its application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element. In addition, the connection may be for either a fixed or coupled or communicating function.

It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the embodiments of the present invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "a plurality" means two or more unless specifically limited otherwise.

Referring to fig. 1 and 2, an embodiment of the present invention provides a transmission-type solid-phase microextraction microfluidic device, including a solid-phase microextraction film 2, an upper microfluidic chip 1 and a lower microfluidic chip 3, wherein upper and lower surfaces of the solid-phase microextraction film 2 are respectively bonded to the upper microfluidic chip 1 and the lower microfluidic chip 3, a flow channel 4 is disposed on a surface of the upper microfluidic chip 1 facing the solid-phase microextraction film 2, and the flow channel 4 is formed as an airtight extract flow channel after the upper microfluidic chip 1 is bonded to the solid-phase microextraction film 2; a liquid storage tank 7 with an opening facing the solid phase micro-extraction film 2 is arranged on the lower micro-fluidic chip 3, and the liquid storage tank 7 is formed into a micro-extraction liquid storage tank 7 after the lower micro-fluidic chip 3 is bonded with the solid phase micro-extraction film 2; the upper microfluidic chip 1 and the lower microfluidic chip 3 have tips bonded together, and the outlets of the flow channels 4 are located at the tips to form nozzles 5 at the tips.

In use, a sample injected into the micro-extraction reservoir 7 is in direct contact with the solid phase micro-extraction membrane 2, an extraction liquid (e.g. an organic solvent such as ethanol) injected into the extraction liquid flow channel performs a permeable solid phase micro-extraction on the sample (e.g. a complex matrix) through the solid phase micro-extraction membrane 2, the sample and the extraction liquid are completely separated, an interference component is retained in the complex matrix, and a target analyte component enters the extraction liquid through the solid phase micro-extraction membrane 2; after the solid phase microextraction is performed, a driving medium is injected into the injection hole 6 of the flow channel 4, and the extract containing the target analyte is driven to be discharged from the nozzle 5. Further, electrospray may be formed by applying high voltage to the extraction liquid. Therefore, the utility model discloses a transmission type solid phase micro-extraction micro-fluidic device not only can realize solid phase micro-extraction, but also can use with the mass spectrograph jointly very conveniently, directly advances the kind of mass spectrograph through the electrospray, realizes the material analysis. The utility model discloses can realize extracting from complicated matrix sample simultaneously and obtain the target analyte who purifies and spray this two kinds of functions of appearance.

In a preferred embodiment, the solid-phase micro-extraction film 2, the upper micro-fluidic chip 1 and the lower micro-fluidic chip 3 are made of PDMS materials. When the solid phase micro-extraction film 2 is made of PDMS material, the micro-fluidic chip can also be glass or other materials which can be bonded with PDMS. Preferably, the PDMS material is prepared by mixing, by mass, 1: 5 to 1: 20 PDMS base fluid was mixed with curing agent. More preferably, the PDMS material is prepared by mixing, by mass, 1: 10 is mixed with a curing agent.

In a preferred embodiment, the liquid storage tank 7 is a chamber penetrating through the upper and lower surfaces of the lower microfluidic chip 3, and the microfluidic device is turned over during solid-phase microextraction, so that the lower microfluidic chip 3 is positioned above the upper microfluidic chip 1.

In a preferred embodiment, the solid phase microextraction membrane 2 covers the entire area of the flow channel 4. It should be understood that the solid phase micro-extraction film 2 is covered between the flow channel 4 and the micro-extraction reservoir 7 to realize solid phase micro-extraction.

In a preferred embodiment, the flow channel 4 is an M-shaped flow channel 4 having a meandering structure at least in a region corresponding to the reservoir 7. The flow channel 4 is designed to be of an M-shaped structure with a winding structure, so that the contact area between the flow channel 4 and the solid-phase micro-extraction film 2 is remarkably increased, the extraction amount can be increased on the premise of not increasing the thickness of the film, the extraction sensitivity is improved, and the extraction efficiency is improved.

In a preferred embodiment, the solid-phase micro-extraction film 2 is bonded to the upper microfluidic chip 1 and the lower microfluidic chip 3 by oxygen plasma bonding.

In a preferred embodiment, the driving medium is an eluent.

Referring to fig. 1 to 5, there is also provided a method for manufacturing the permeable solid-phase microextraction microfluidic device, comprising the steps of:

respectively manufacturing a solid phase micro-extraction film 2, an upper micro-fluidic chip 1 and a lower micro-fluidic chip 3, wherein a flow channel 4 is formed on one surface of the upper micro-fluidic chip 1 facing the solid phase micro-extraction film 2, and a liquid storage tank 7 with an opening facing the solid phase micro-extraction film 2 is arranged on the lower micro-fluidic chip 3;

bonding the upper-layer micro-fluidic chip 1 with one surface of the solid-phase micro-extraction film 2 to form the flow channel 4 into a closed extraction liquid flow channel; bonding the lower microfluidic chip 3 with the other surface of the solid-phase microextraction film 2 to form a liquid storage tank 7 into a microextraction liquid storage tank 7; wherein the upper microfluidic chip 1 and the lower microfluidic chip 3 have tips bonded together, and the outlet of the flow channel 4 is located at the tips to form a nozzle 5 at the tips.

In a preferred embodiment, the solid-phase micro-extraction film 2, the upper microfluidic chip 1, and the lower microfluidic chip 3 are PDMS, and the mass ratio of the PDMS to the micro-extraction film is 1: 5 to 1: 20, more preferably 1: 10 is mixed with a curing agent.

In a preferred embodiment, the solid-phase micro-extraction film 2 is prepared by a spin coating method using a silicon wafer with a sacrificial layer, and the upper micro-fluidic chip 1 and the lower micro-fluidic chip 3 are prepared by a soft lithography process.

The permeable solid phase microextraction microfluidic device and process for making the same according to embodiments of the present invention are described further below.

As shown in fig. 1 to 3, the transmissive solid-phase microextraction microfluidic device includes a solid-phase microextraction film 2, and upper and lower microfluidic chips 1 and 3, wherein the solid-phase microextraction film 2 is bonded with the upper and lower microfluidic chips 1 and 3 to form a sandwich structure. The solid phase microextraction membrane 2 is internally protected. PDMS is selected as the material of the solid phase micro-extraction film 2 and the micro-fluidic chip. The solid phase micro-extraction film 2 can be prepared by a whirl coating method and a sacrificial layer. The micro-fluidic chip can be processed by soft lithography, and the bonding film and the chip are bonded by oxygen plasma. The flow of manufacturing a solid phase microextraction microfluidic device is shown in figure 3.

The upper and lower layers of micro-fluidic chips 1 and 3 and the PDMS solid phase micro-extraction film 2 are bonded by plasma to form a solid phase micro-extraction micro-fluidic device with a sandwich structure, and can be used with mass spectra to realize the dual purposes of solid phase micro-extraction and sample injection. The upper microfluidic chip 1 and the PDMS solid phase micro-extraction film 2 are bonded to form an M-shaped closed flow channel. The upper microfluidic chip 1 also serves as a microfluidic elution module. The lower microfluidic chip 3 is used as a microfluidic liquid storage module and is bonded with the PDMS micro-extraction film to form a liquid storage tank which can contain a sample. The biological sample is directly injected into the liquid storage tank and directly contacted with the PDMS micro-extraction film for permeation micro-extraction. After solid phase microextraction is carried out, eluent is injected into the flow channel through an eluent injection pipe 8, so that extract liquid containing target analytes is discharged from a nozzle, and high voltage is applied to the extract liquid to form electrospray, so that sample injection into a mass spectrometer is realized.

The PDMS solid phase micro-extraction film is bonded with the microfluidic elution module to form a flow channel for transporting and controlling the extraction liquid, and is bonded with the microfluidic liquid storage module to form a liquid storage tank for storing a complex matrix sample. During extraction, interfering components (inorganic salts, proteins and fats) in the complex matrix cannot penetrate through the PDMS film and enter the extraction liquid, and target components (malachite green, crystal violet, phenolphthalein and the like) can penetrate through the PDMS film and enter the extraction liquid.

Use the utility model discloses carry out sample pretreatment with transmission type solid phase micro-extraction micro-fluidic device to complicated matrix, get rid of interference components such as protein, inorganic salt, fat in the sample, only let target component (for example malachite green and crystal violet of illegal interpolation in the fish flesh of fish blood, phenolphthalein of illegal interpolation in the health products) permeate solid phase micro-extraction film 2 and get into in the extract from sample solution to joint mass spectrograph (or other detecting instrument) carries out quantitative determination to it.

In addition, the utility model discloses with the micro-fluidic device of penetrating formula solid phase micro-extraction can also be used to the realization to the purification of specific target analyte.

The permeable solid phase micro-extraction micro-fluidic device has the following specific using process:

(1) and (3) loading: before sample loading, the permeation micro-extraction micro-fluidic chip is taken out and is preprocessed. And (3) using a pipette to pipette 90 mul of extraction liquid into the extraction flow channel of the microfluidic chip, and cleaning and activating the micro-extraction film. Then, 10 μ l of the extract liquid is added into the microfluidic chip extraction flow channel, and because the volume of the microfluidic chip extraction flow channel is 10 μ l, the extract liquid can be temporarily stored in the flow channel without loss. The microfluidic chip was turned over, 300 μ l of fish blood sample was added, and then placed on a clean petri dish for micro-extraction. Wherein, the extraction time of malachite green is 20min, the extraction time of crystal violet is 40min, and the extraction time of malachite green and crystal violet is 40 min.

(2) And (3) an elution process: after the micro-extraction, the fish blood sample is recovered, a transmission type micro-fluidic chip containing 10 mu l of extraction liquid is placed on a three-dimensional translation table, and the XYZ axes are adjusted to enable an electrospray nozzle of the chip to be aligned with the inlet of the mass spectrum. Eluent (identical in composition to the extract) was injected into the extraction flow channel at a rate of 2. mu.l/min by means of the reservoir of the microfluid drive control system. 4.5KV high-voltage direct current is loaded on the micro-fluidic chip to form electrospray.

(3) And (3) recording: and recording the mass spectrum image by using a computer, so as to be convenient for analysis after the experiment is finished.

Manufacture of solid phase microextraction film

The material of the solid phase microextraction film is preferably PDMS. The method for fabricating the PDMS solid phase microextraction film is described below.

Reagent and apparatus

The reagents used in the fabrication of the microextraction membrane were: SU-8 negative adhesive 2025, acetone, deionized water, PDMS base liquid and curing agent. Acetone and deionized water were both chromatographic grade. The reagent details are shown in Table 1. The equipment used in the manufacturing process is as follows: a glue homogenizing machine, a hot plate, a vacuum drier and a constant temperature oven. The specific information and uses are as follows:

TABLE 1 microextraction film manufacturing Process reagents

The highest temperature of the hot plate can reach 300 ℃, the heating rate can be controlled, the heating is carried out in stages, and the function of taking the lifting piece at regular time is achieved.

The rotating speed adjusting range of the glue homogenizing machine is 300-8000 rpm, the setting range of the glue homogenizing time is 0-200s, the glue homogenizing process can be completed in a segmented mode through different rotating speeds, and the sizes of the trays are 2 inches, 3 inches, 4 inches and 6 inches.

The vacuum drier is used for defoaming PDMS.

Preparation of solid phase micro-extraction film

The preparation method of the PDMS solid phase microextraction film mainly comprises the following steps: preparing liquid, defoaming in vacuum, preparing a sacrificial layer and preparing a PDMS film. The specific process flow is as follows:

(1) preparing liquid: preparing a curing agent of PDMS: the mass ratio of the PDMS base liquid is 1: 5 to 1: 20. the more the content of the solid phase agent is, the higher the crosslinking strength is, the fewer the uncrosslinked oligomer molecules are, and the less the solid phase is separated out during the micro-extraction; but at the same time the more brittle the film will be and will be prone to cracking. Preferably, the curing agent: the proportion of the PDMS base liquid is 1: 10. stirring for 5min with a clean glass rod to mix the PDMS base solution and the curing agent uniformly.

(2) Vacuum defoaming: and (3) placing the uniformly mixed PDMS material into a vacuum drier for defoaming for 15 minutes, and taking out the PDMS when no obvious bubbles exist. In order to prevent dust in the air from entering the PDMS, the mouth of the container containing the PDMS may be sealed with a preservative film.

(3) Preparing a sacrificial layer: negative photoresist (SU-82025) was poured onto a 3 inch silicon wafer and spin-coated with a spin coater at 6000rpm for 30 seconds. The silicon wafer was transferred to a hot plate at 120 ℃ and baked for 6 min. Some of the wafer edge is exposed due to evaporation of water from the photoresist, becoming covered by the photoresist to become a bare silicon surface.

(4) Preparation of PDMS film: pouring PDMS on a silicon wafer with a sacrificial layer, homogenizing the PDMS for 30s by a homogenizer at the rotating speed of 6000rpm, and then baking the PDMS on a hot plate at 120 ℃ for 10min, wherein the central part of the PDMS film is directly bonded with the silicon wafer at the exposed edge part of the silicon wafer through the sacrificial layer. Because the PDMS film is bonded with the silicon chip at the edge part, the whole PDMS film can be kept flat, and the bonding of the PDMS film and the upper microfluidic chip is prevented from being influenced by the self-curling of the PDMS. The silicon wafer was placed in a petri dish and wrapped in tinfoil paper to prevent exposure to SU-82025 negative photoresist.

Micro-extraction chip fabrication

The reagents used in the fabrication of the micro-extraction chip are: the adhesive comprises the following components of SU-8 negative adhesive 2100, SU-8 negative adhesive developing solution, isopropanol, deionized water, PDMS base solution and curing agent. Both isopropanol and deionized water were of chromatographic grade. The reagents are shown in Table 2.

TABLE 2 micro-extraction chip fabrication Process reagents

The equipment used in the manufacturing process comprises a spin coater, a hot plate, a vacuum dryer, a constant temperature oven and a photoetching machine. Wherein the spin coater, the hot plate, the vacuum dryer and the constant temperature oven are as described above, and the photoetching machine can generate ultraviolet light to enable SU-8 negative photoresist to generate a crosslinking reaction.

Silicon wafer template photoetching process

The silicon wafer template 10 for manufacturing the upper and lower microfluidic chips is prepared by adopting a standard photoetching process. The photoetching process mainly comprises the following steps according to the processing sequence: preparing a wafer, spin-coating negative SU-82100 photoresist, soft baking, ultraviolet exposure, baking after exposure, developing, hard baking, and checking.

(1) Preparing a wafer: taking a disposable glove, taking the clean 3-inch silicon wafer out of a storage room by using tweezers, and baking the silicon wafer on a hot plate at the temperature of 120 ℃ for 15 minutes to completely remove water possibly attached on the surface of the silicon wafer, so that the photoresist can be favorably adhered to the surface of the silicon wafer.

(2) Spin coating negative SU-82100 photoresist: the SU-82100 photoresist is selected to ensure that the depth of the flow channel reaches 130um, so that the flow resistance of the whole flow channel is small, and when eluent is injected into the flow channel, the film cannot be broken. Leveling a spin coater before spin coating. The photoresist is homogenized in 2 stages, the rotating speed of the first stage is 500rpm, spin coating is carried out for 20 seconds, and the photoresist is spread on the surface of the silicon wafer. The rotation speed of the second stage is 2500rpm, the spin coating is carried out for 30 seconds, and the thickness of the photoresist is controlled to be about 130 um. In order to ensure that the photoresist is uniformly distributed on the silicon wafer and the viscosity of the SU-2100 photoresist is high, the photoresist is kept stand for 30 minutes.

(3) Soft baking: leveling the hot plate, and setting a hot plate heating mode when the photoresist is static. The first stage, heating at constant speed from 20 deg.C to 95 deg.C at 15 deg.C/min; the second stage, constant temperature stage, keeping 95 deg.C for 12 min; and the third stage, cooling to room temperature with natural air. A stage of uniform heating is designed, so that the photoresist can be effectively prevented from being suddenly heated, and the internal mechanical stress is uneven, so that the photoresist is degummed after exposure. And (3) placing the silicon wafer in the center of the hot plate, and heating according to the set heating mode. The purpose of this step is to slightly remove the water from the photoresist in preparation for exposure.

(4) Ultraviolet exposure: the mask plate 9 is attached to a glass plate, a silicon wafer is placed on a 3-inch disk of a photoetching machine, and the silicon wafer is adsorbed on the glass plate on a photoetching table by a vacuum pump for exposure. The exposure time takes into account three factors, firstly, the ultraviolet light power of the photoetching machine; second, the thickness of the photoresist; third, the area of the flow channel. The exposure time is preferably 20s, and the runner degumming after exposure is avoided on the premise of obtaining a runner with a larger area.

(5) Baking after exposure: the silicon wafer was baked for 15min in the center of a hot plate at 95 ℃. This step provides energy to crosslink the exposed photoresist. And (3) baking the silicon wafer immediately after the silicon wafer is taken off from the photoetching table to ensure complete crosslinking.

(6) And (3) developing: and (4) moving the cooled and baked silicon wafer to a developing solution by using tweezers to develop for 5 min. The silicon wafer can be slightly swung by tweezers to enable the developing solution to wash the flow channel. And taking out the silicon wafer when the micro-channel is developed clearly. Washing the silicon wafer with isopropanol, and if no white floccule appears, proving that the development is complete; and white floc appears, and the silicon wafer is continuously developed. And (4) drying the developed silicon wafer by using nitrogen, and carrying out the next step. The developing time cannot be too long, which can weaken the adhesion between the photoresist and the silicon wafer and may cause debonding.

(7) Hard baking: and (3) placing the silicon wafer on a hot plate at 120 ℃ for baking for 2 hours, and further eliminating the mechanical stress in the photoresist.

(8) Checking: and (3) placing the silicon chip under an optical microscope, selecting a proper multiple to check, and observing whether the flow channel is complete or not and whether the flow channel is deficient or not.

Referring to fig. 3 and 4, the above process obtains a silicon wafer template 11 for fabricating an upper microfluidic chip and a silicon wafer template 12 for fabricating a lower microfluidic chip.

PDMS microfluidic chip manufacturing process

PDMS is a chemically inert transparent material, has a simple processing technology, and can accurately transfer the micro-channel pattern on the template. The preparation of the PDMS microfluidic chip can comprise the following steps: preparing liquid, defoaming in vacuum, pouring a silicon wafer, defoaming in vacuum, heating and baking, stripping and demolding, and cutting and punching, wherein the specific process flow is as follows:

(1) preparing liquid: PDMS consists of a base fluid and a curing agent, which was accurately weighed in the experiment using an electronic balance: the base liquid ratio is 1: 10 PDMS was stirred with a clean glass rod for 5min to mix the base solution and the curing agent.

(2) Vacuum defoaming: and (3) placing the uniformly mixed PDMS into a vacuum drier for defoaming for 15 minutes, and taking out the PDMS when no obvious bubbles exist. In order to prevent dust in the air from entering the PDMS, the mouth of the container containing the PDMS may be sealed with a preservative film.

(3) Casting a silicon wafer: and pouring PDMS on the edge of the silicon chip to enable the PDMS to naturally flow to cover the runner. The thickness is controlled between 4mm and 6 mm. With a thickness of less than 3mm, cracks tend to occur at the perforations due to the force applied to the perforations when the eluent is injected with a steel needle. Above 8mm thickness, the perforation may be difficult because the needle of the perforator is only 1 cm.

(4) Vacuum defoaming: and (3) placing the silicon wafer template poured with the PDMS into a vacuum drier, and defoaming for 20 minutes. When there were no significant air bubbles in the dish, the dish was removed from the vacuum desiccator and the air bubbles on the PDMS surface were blown off with an ear wash.

(5) Heating and baking: the oven was set to 80 ℃ and the dish was placed flat and baked for 30 minutes.

(6) Stripping and demolding: the petri dish was removed and carefully cut with a scalpel along the edge of the silicon wafer template, and must be bottomed out. The PDMS was carefully and slowly peeled off the silicon template, at which point the micro-channel pattern on the template had been transferred to the PDMS.

(7) Cutting and punching: and cutting PDMS along the edge of the chip by using a scalpel to obtain an elution module and a liquid storage module of the microfluidic chip. For the elution module, punch at the injection port with a 0.75mm diameter punch: for the liquid storage module, a scalpel is used for penetrating through the liquid storage tank.

The demolding and punching process is described with reference to fig. 5.

Bonding of microfluidic chip and microextraction film

As the last step of the manufacturing of the permeation type micro-extraction micro-fluidic chip, the method is also the greatest innovation point of the research, namely the purification of complex matrix and the sample introduction are organically combined into the micro-fluidic chip. Wherein, the purification matrix is completed by a PDMS micro-extraction film, the sample introduction is completed by a PDMS micro-fluidic chip, and the bonding of the two is the organic combination of the functions. Meanwhile, in order to further improve the signal to noise ratio, the transmission type microextraction microfluidic chip is pretreated to be clean, and mass spectrum background noise of PDMS during mass spectrum sample introduction is eliminated as much as possible.

The reagents used for bonding and pretreatment may include deionized water and acetone, both of which are chromatographic grade. The used equipment mainly comprises a constant temperature oven and an oxygen plasma cleaning machine.

The bonding mainly comprises the following steps: removing a sacrificial layer, bonding an elution module and a film, soft baking, bonding a liquid storage module and a film, hard baking and preprocessing. The specific process flow is as follows:

(1) removing the sacrificial layer: the silicon wafer with the surface covered with PDMS was placed in acetone for 30 minutes to remove the sacrificial layer between the silicon wafer and the thin film. After the sacrificial layer is completely removed and cleaned, only the edge of the silicon wafer is connected with the PDMS, and the cured PDMS still keeps flat. By this operation, not only the sacrificial layer is removed, but the PDMS film is also pre-treated to wash away the oligomers in the film that are not PDMS coupled. The silicon wafer is then placed in deionized water for 10 minutes to clean the acetone therein.

(2) Elution module and membrane bonding: the elution module was placed into a plasma cleaner with the flow channel side up and surface treated for 2 minutes. And (4) after taking out the elution module, quickly cleaning the surface of the PDMS flow channel by using an adhesive tape, removing surface dust, and directly reversing the PDMS flow channel on the PDMS film.

(3) Soft baking: and putting the elution module and the PDMS film connected with the silicon wafer into a constant-temperature oven at 80 ℃ for soft baking for 10 min. And then taking out the silicon wafer, and removing the connection between the thin film at the edge of the silicon wafer and the silicon wafer by using a cutter. Then, the film is firstly uncovered from the periphery of the silicon wafer to the center of the silicon wafer to the bonding position with the edge of the microfluidic chip, and then the film is integrally uncovered from the silicon wafer together with the elution module. Then, it was baked in an oven at 120 ℃ for 2 hours.

(4) Liquid storage module and thin film bonding: the liquid storage module was placed in a plasma cleaner with the smooth surface facing up, and surface treated for 2 minutes. After the liquid storage module is taken out, the smooth surface is quickly cleaned by using an adhesive tape, and the liquid storage module and the thin film on the elution module are bonded together after being aligned.

(5) Hard baking: the chip is placed into an oven at 80 ℃ for baking for 72h to enhance the bonding strength, and the PDMS is further cured for setting.

(6) Pretreatment: the fully cured chip was removed by first carefully cutting off the excess film exposed outside the chip with a scalpel and then placing the chip in acetone for 2 hours. This step was to further eliminate the effect of unlinked oligomers in the chip on the mass spectrum. The principle is that the unlinked oligomer in the chip is washed out in advance, so that the mass spectrum background is not interfered by the chip when the sample is injected. The chip was then placed in deionized water for 3 hours and acetone and oligomers were washed away.

The whole process of preparing the permeable solid-phase microextraction microfluidic device is shown in figure 3.

The background section of the present invention may contain background information related to the problems or the environment of the present invention and is not necessarily descriptive of the prior art. Accordingly, the inclusion in the background section is not an admission of prior art by the applicant.

The foregoing is a more detailed description of the present invention, taken in conjunction with the specific/preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments shown and described. For those skilled in the art to which the invention pertains, a plurality of alternatives or modifications can be made to the described embodiments without departing from the concept of the invention, and these alternatives or modifications should be considered as belonging to the protection scope of the invention. In the description herein, references to the description of the term "one embodiment," "some embodiments," "preferred embodiments," "an example," "a specific example," or "some examples" or the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Various embodiments or examples and features of various embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the claims.

Claims (6)

1. A transmission type solid phase micro-extraction micro-fluidic device is characterized by comprising a solid phase micro-extraction film, an upper micro-fluidic chip and a lower micro-fluidic chip, wherein the upper surface and the lower surface of the solid phase micro-extraction film are respectively bonded with the upper micro-fluidic chip and the lower micro-fluidic chip; the lower micro-fluidic chip is provided with a liquid storage tank with an opening facing the solid phase micro-extraction film, and the liquid storage tank is formed into a micro-extraction liquid storage tank after the lower micro-fluidic chip is bonded with the solid phase micro-extraction film; the upper and lower microfluidic chips have tips bonded together, and the outlets of the flow channels are located at the tips to form nozzles at the tips.

2. The transmissive solid phase microextraction microfluidic device of claim 1, wherein said solid phase microextraction membrane, said upper microfluidic chip, and said lower microfluidic chip are PDMS materials.

3. The transmissive solid-phase microextraction microfluidic device according to claim 1 or 2, wherein said reservoir is a chamber through the upper and lower surfaces of said lower microfluidic chip, and said microfluidic device is inverted during solid-phase microextraction so that said lower microfluidic chip is positioned above said upper microfluidic chip.

4. The transmissive solid phase microextraction microfluidic device of claim 1 or 2, wherein said solid phase microextraction membrane covers the entire area of said flow channel.

5. The microfluidic device according to claim 1 or 2, wherein the flow channel is an M-shaped flow channel having a meandering structure at least in a region corresponding to the reservoir.

6. The transmissive solid phase microextraction microfluidic device of claim 1 or 2, wherein said solid phase microextraction membrane is bonded to said upper microfluidic chip and said lower microfluidic chip by oxygen plasma bonding.

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