A sers microfluidic chip and a manufacturing method thereof

Abstract

The application relates to the field of micro-nano optical mechanical and electrical technology, and particularly relates to a SERS micro-fluidic chip and a manufacturing method thereof. The SERS micro-fluidic chip comprises a SERS substrate and a micro-fluidic chip, the SERS substrate is connected to the output channel end of the micro-fluidic chip, the input end of the micro-fluidic channel is used for inputting a sample solution to be detected, and the SERS substrate is a porous silicon carbide substrate. The SERS substrate is manufactured by using a porous silicon carbide material, and automatic adsorption of silver nanoparticles is realized by using an electrochemical deposition method, so that a Raman enhancement substrate can be manufactured, the manufacturing process is simple, the processing efficiency is high, the preparation cost is low, the repeatability is good, the stability is high, and the SERS activity is high; and the micro-fluidic chip can realize rapid, efficient, high-sensitivity and high-throughput differential detection on different concentrations of substances.

Description

Technical Field

[0001] This invention relates to the field of micro-nano opto-electro-mechanical technology, specifically to a SERS microfluidic chip and its fabrication method. Background Technology

[0002] Surface-enhanced Raman spectroscopy (SERS) is characterized by its excellent enhancement effect, high sensitivity, and good specificity, and is widely used in chemical detection and biological analysis. The enhancement effect of the Raman-enhancing substrate is achieved through micro / nano structures, particles, or colloids of noble metals. When excited by light, the electromagnetic field intensity on the Raman-enhancing substrate increases significantly, which can be used to enhance the Raman scattering signal of the analyte. The application of microfluidic chip analysis technology has become a development trend in biochemical analysis and detection. Compared with other analytical testing methods, microfluidic-based biochemical analysis has the advantages of high detection efficiency, low reagent consumption, easy integration, and convenient use, and has broad application prospects in many fields such as biomedicine, food safety, and environmental monitoring.

[0003] Chinese invention patent application CN1811389A discloses a microfluidic chip with a surface-enhanced Raman spectroscopy (SERS) active substrate and its fabrication method. Specifically, the microfluidic chip has at least one microchannel, and a rough metal thin film with SERS activity is formed on all or part of the inner wall surface of the microchannel. During fabrication, grooves are processed on a glass or polymer sheet; in all or part of the groove area, a coin group metal thin film is prepared using physical evaporation, sputtering, or chemical deposition combined with masking techniques. However, the preparation and storage of uniform metal nanoparticles are difficult, and they easily aggregate and settle unstably, greatly limiting their application range. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a SERS microfluidic chip and its fabrication method. The SERS substrate is made of porous silicon carbide material, and the automatic adsorption of silver nanoparticles is achieved using electrochemical deposition. This allows for the fabrication of a Raman-enhanced substrate. The fabrication process is simple, efficient, low-cost, reproducible, and stable, and it exhibits high SERS activity. This type of microfluidic chip enables rapid, efficient, sensitive, and high-throughput differential detection of substances of different concentrations.

[0005] This invention provides a SERS microfluidic chip, comprising a SERS substrate and a microfluidic chip, wherein the SERS substrate is connected to the output channel of the microfluidic chip, and the input end of the microfluidic channel is used to input the sample solution to be detected. The SERS substrate is a porous silicon carbide substrate.

[0006] This invention also provides a method for fabricating a SERS microfluidic chip, comprising the following steps:

[0007] SERS substrates and microfluidic chips were fabricated separately.

[0008] The microfluidic chip is bonded to the SERS substrate and glass slide, and a liquid inlet and a liquid outlet are provided to obtain the SERS microfluidic chip.

[0009] The SERS substrate is made of porous silicon carbide material and silver nanoparticles are prepared by electrochemical deposition and automatic adsorption of silver nanoparticles.

[0010] More preferably, the method for fabricating the SERS substrate includes:

[0011] The pretreated porous silicon carbide wafers are immersed in silver nitrate solution;

[0012] Add hydrogen peroxide solution to silver nitrate solution;

[0013] Add PVP solution to silver nitrate solution;

[0014] Silver nanoparticles were obtained by electrochemical deposition of sodium hydroxide solution into silver nitrate solution.

[0015] A porous silicon carbide wafer automatically adsorbs silver nanoparticles to obtain a SERS substrate.

[0016] Preferably, the volume ratio of the hydrogen peroxide solution, sodium hydroxide solution and silver nitrate solution is 1:1:1.

[0017] Preferably, the amount of PVP solution added is 0.8 to 1.5 ml.

[0018] Preferably, the preprocessing includes:

[0019] The porous silicon carbide material is cut to obtain porous silicon carbide material sheets;

[0020] The porous silicon carbide material sheet was sequentially cleaned of surface contaminants using hydrochloric acid, acetone, and ethanol solutions.

[0021] The porous silicon carbide material sheet was cleaned of surface oxides using dilute sulfuric acid.

[0022] The porous silicon carbide material sheet was washed with deionized water;

[0023] Fix the cleaned porous silicon carbide material sheet and dry the surface with nitrogen gas.

[0024] More preferably, the method for fabricating the microfluidic chip includes:

[0025] Design microfluidic channels for microfluidic chips;

[0026] Silicon anode templates for chip fabrication using photolithography;

[0027] Pour the prepared PDMS mixture into a culture dish with the silicon anodic template attached, remove air bubbles, and then place it in an oven for heating.

[0028] The PDMS chip is peeled off with a cutting tool and cut into individual pieces to obtain a single-layer microfluidic chip.

[0029] Preferably, the microfluidic channel is a Y-shaped channel driven by capillary force. The microfluidic channel includes a main body section and two liquid inlet sections. The liquid inlet sections are symmetrically arranged at the front end of the main body section and communicate with the front end of the main body section. The end of the liquid inlet section is a liquid inlet, and the rear end of the main body section is a liquid outlet. The liquid outlet is connected to the SERS substrate groove below the microfluidic channel.

[0030] Preferably, the microfluidic channel is 12-15 mm wide, 32-38 mm long, and 1-3 mm deep. The main body section and the liquid inlet section are 1-3 mm wide. The SERS base groove is disposed at the bottom of the liquid inlet section of the microfluidic channel. The SERS base groove is a square groove with a side length of 7-9 mm.

[0031] Preferably, the bonding of the microfluidic chip to the SERS substrate and glass slide includes:

[0032] The SERS substrate storage area was cut out on a glass slide using CNC cutting technology;

[0033] The prepared monolayer microfluidic chip and glass slide were ultrasonically cleaned with ethanol, and then dried with oxygen plasma.

[0034] The SERS substrate is placed in the SERS substrate storage area on a glass slide, and the microfluidic chip is bonded to the glass slide.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. A porous silicon carbide substrate was used to fabricate a SERS substrate. Silver nanoparticles were then deposited using an electrochemical deposition method. Through the adsorption effect of the porous silicon carbide, the contacting silver nanoparticles generated hotspots. This physical enhancement significantly amplified the Raman signal, making it highly sensitive, with a limit reaching 10⁻⁶. -12 mol / L. This method is simple to prepare, low in cost, highly efficient, highly stable, produces little contamination, mixes uniformly, and is widely used. It can integrate multiple steps such as sample preparation, mixing, separation, and detection to achieve a fully automated analytical workflow.

[0037] 2. The microfluidic channel is a Y-shaped channel driven by capillary force. The microfluidic channel includes a main body section and two inlet sections. The inlet sections are symmetrically arranged at the front end of the main body section and communicate with the front end of the main body section. The end of each inlet section is an inlet, and the rear end of the main body section is an outlet. The outlet is connected to a SERS substrate groove below the microfluidic channel. The Y-shaped capillary force-driven microfluidic channel utilizes the capillary phenomenon, eliminating the need for an external pump to drive the fluid. This simplifies the system and reduces equipment costs.

[0038] 3. Integrating Raman-enhanced substrates (SERS substrates) with microfluidic devices to fabricate SERS microfluidic chips. This allows for faster analysis speeds and real-time monitoring by precisely controlling sample flow rate and mixing. Simultaneous analysis of multiple molecules can be achieved through the design of microfluidic channels. Complex detection of mixed solutions of acetamiprid and carbendazim was realized, detecting different peak values ​​and their corresponding concentrations. This lays the foundation for the application of Raman-enhanced substrates in biochemical analysis, optoelectronics, and medical diagnostics. Attached Figure Description

[0039] Figure 1 This is a first-angle three-dimensional schematic diagram of the SERS microfluidic chip of the present invention;

[0040] Figure 2 This is a second-angle three-dimensional schematic diagram of the SERS microfluidic chip of the present invention;

[0041] Figure 3 This is a front view of the SERS microfluidic chip of the present invention;

[0042] Figure 4 This is a schematic diagram of the process for fabricating the SERS substrate of the present invention;

[0043] Figure 5 This is a schematic diagram showing the comparison of electric field simulations after electrochemical deposition of silver nanoparticles with different thicknesses according to the present invention.

[0044] Figure 6 Schematic diagram of the Raman-enhanced substrate enhancement effect of electrochemically deposited substrates with different silver nitrate concentrations;

[0045] Figure 7 Raman spectrum of R6G measured on SERS substrate;

[0046] Figure 8 Raman waterfall plot obtained from the homogeneity test of the SERS substrate;

[0047] Figure 9 A schematic diagram of the relative standard deviation obtained from the homogeneity test of the SERS substrate;

[0048] Figure 10Raman spectra of acetamiprid detected using a SERS microfluidic chip;

[0049] Figure 11 Raman spectra of carbendazim solid powder detected using a SERS microfluidic chip;

[0050] Figure 12 Raman spectra of acetamiprid solutions at different concentrations were obtained using a SERS microfluidic chip.

[0051] Figure 13 A schematic diagram showing the linear relationship between characteristic peaks and concentration in Raman spectra of acetamiprid solutions of different concentrations detected by a SERS microfluidic chip.

[0052] Figure 14 Raman spectra of carbendazim solutions of different concentrations were detected using a SERS microfluidic chip.

[0053] Figure 15 A schematic diagram showing the linear relationship between characteristic peaks and concentration in Raman spectra of carbendazim solutions of different concentrations detected by a SERS microfluidic chip;

[0054] Figure 16 Raman spectra of a mixture of acetamiprid and carbendazim detected by a SERS microfluidic chip.

[0055] In the figure: 1-microfluidic channel, 101-inlet section, 102-main body section, 103-inlet port, 104-main body section, 2-SERS substrate groove. Detailed Implementation

[0056] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0057] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0058] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying 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 this application, "multiple" means two or more, unless otherwise explicitly specified.

[0060] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0061] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0062] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0063] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0064] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means "two or more."

[0065] Example 1

[0066] Figure 1-3 A schematic diagram of a SERS microfluidic chip according to a preferred embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0067] The present invention provides a SERS microfluidic chip, comprising a SERS substrate and a microfluidic chip, wherein the SERS substrate is connected to the output channel end of the microfluidic chip, and the input end of the microfluidic channel 1 is used to input the sample solution to be detected. The SERS substrate is a porous silicon carbide substrate.

[0068] The microfluidic channel is a Y-shaped channel driven by capillary force. The microfluidic channel includes a main body section and two liquid inlet sections. The liquid inlet sections are symmetrically arranged at the front end of the main body section and communicate with the front end of the main body section. The end of the liquid inlet section is the liquid inlet, and the rear end of the main body section is the liquid outlet. The liquid outlet is connected to the SERS substrate groove below the microfluidic channel.

[0069] In one embodiment, the SERS microfluidic chip has an overall length of 46mm, a width of 24mm, and a height of 3mm. The microfluidic channel is 12-15mm wide, 32-38mm long, and 1-3mm deep. The main body section and the liquid inlet section are 1-3mm wide. The SERS substrate groove is located at the bottom of the liquid inlet section of the microfluidic channel. The SERS substrate groove is a square groove with a side length of 7-9mm. In this embodiment, the main body section and the liquid inlet section are preferably 2mm wide and 2mm deep, with a total length of 35mm and a total width of 14mm. The surface of the SERS substrate groove is a square with a side length of 8mm and a thickness of 1mm.

[0070] Example 2

[0071] This embodiment also provides a method for fabricating a SERS microfluidic chip, including the following steps:

[0072] Step 1, create the SERS substrate;

[0073] Step 2: Fabricate the microfluidic chip;

[0074] Step 3: Bond the microfluidic chip to the SERS substrate and glass slide, and set the liquid inlet and liquid outlet to obtain the SERS microfluidic chip;

[0075] The SERS substrate is made of porous silicon carbide material and silver nanoparticles are prepared by electrochemical deposition and automatic adsorption of silver nanoparticles.

[0076] In one embodiment, step 1, the method for fabricating the SERS substrate, includes:

[0077] Step 101: Pre-treat the porous silicon carbide;

[0078] include:

[0079] The porous silicon carbide material was cut to obtain a porous silicon carbide material sheet with a size of 1cm×1cm;

[0080] The porous silicon carbide material sheet was cleaned of surface contaminants sequentially using hydrochloric acid, acetone and ethanol solutions, with each solution cleaning for 10 minutes.

[0081] The porous silicon carbide material sheet was cleaned of surface oxides for 10 minutes using dilute sulfuric acid (1:100) to deeply clean the impurities on the surface.

[0082] The porous silicon carbide material sheet was washed with deionized water for 5 minutes.

[0083] Fix the cleaned porous silicon carbide material sheet and dry the surface with nitrogen gas.

[0084] Step 102: Immerse the pretreated porous silicon carbide wafer in a 20mM silver nitrate solution;

[0085] Step 103: Add hydrogen peroxide solution to silver nitrate solution;

[0086] Step 104: Add PVP solution to silver nitrate solution;

[0087] Step 105: Add sodium hydroxide solution to silver nitrate solution and perform electrochemical deposition to obtain silver nanoparticles;

[0088] The volume ratio of hydrogen peroxide solution, sodium hydroxide solution, and silver nitrate solution added is 1:1:1, and 1 ml of PVP solution is added to prevent the aggregation of silver nanoparticles generated in the reaction.

[0089] Step 106, reaction time 8-10 minutes, silver nanoparticles are automatically adsorbed through porous silicon carbide wafer to obtain SERS substrate.

[0090] In one embodiment, step 2, the method for fabricating the microfluidic chip, includes:

[0091] Step 201: Design the microfluidic channels of the microfluidic chip;

[0092] The microfluidic channel is a Y-shaped channel driven by capillary force. The microfluidic channel includes a main body section and two liquid inlet sections. The liquid inlet sections are symmetrically arranged at the front end of the main body section and communicate with the front end of the main body section. The end of the liquid inlet section is the liquid inlet, and the rear end of the main body section is the liquid outlet. The liquid outlet is connected to the SERS substrate groove below the microfluidic channel.

[0093] In one embodiment, the SERS microfluidic chip has an overall length of 46mm, a width of 24mm, and a height of 3mm. The microfluidic channel is 12-15mm wide, 32-38mm long, and 1-3mm deep. The main body section and the liquid inlet section are 1-3mm wide. The SERS substrate groove is located at the bottom of the liquid inlet section of the microfluidic channel. The SERS substrate groove is a square groove with a side length of 7-9mm. In this embodiment, the main body section and the liquid inlet section are preferably 2mm wide and 2mm deep, with a total length of 35mm and a total width of 14mm. The surface of the SERS substrate groove is a square with a side length of 8mm and a thickness of 1mm.

[0094] Step 202: Prepare the silicon anode template for the chip using photolithography.

[0095] The silicon wafer was ultrasonically cleaned in ethanol. Then, the cleaned wafer was placed on a heating platform and heated for 20-30 minutes to ensure complete drying. SU-8 photoresist was spin-coated onto the wafer to remove any accumulated photoresist at the edges, and the wafer was spin-coated at 2000 rpm for 40 seconds. The photoresist was then exposed to ultraviolet light, followed by baking at 90°C for 3 minutes. Finally, the wafer was developed in a developer solution, then placed back on the heating plate and baked until completely dry, yielding a silicon anode template with micro / nano channel structures.

[0096] Step 203: Pour the prepared PDMS mixture into a culture dish with the silicon anodic template attached, remove air bubbles, and then place it in an oven for heating.

[0097] The process involves mixing the PDMS base agent and the curing agent at a mass ratio of 10:1, stirring until homogeneous, removing air bubbles using vacuum extraction, and then placing the PDMS layer in an oven at 80°C for 30 minutes to cure.

[0098] Step 204: Use a cutting tool to peel off the PDMS chip and cut it into single pieces to obtain a single-layer microfluidic chip.

[0099] In one embodiment, step 3 involves bonding the microfluidic chip to the SERS substrate and glass slide, and setting a liquid inlet and a liquid outlet to obtain the SERS microfluidic chip, comprising:

[0100] Step 301: A 1mm × 1mm × 0.5mm SERS substrate storage area is cut out on the glass slide using CNC cutting technology to serve as the detection area;

[0101] Step 302: The prepared monolayer microfluidic chip and glass slide are ultrasonically cleaned with ethanol, and then dried with oxygen plasma.

[0102] Step 303: Place the SERS substrate into the SERS substrate storage area on the glass slide, and bond the microfluidic chip to the glass slide to achieve integration.

[0103] Example 3

[0104] This embodiment provides a testing method for Raman enhancement experiments using a SERS microfluidic chip, specifically including the following steps:

[0105] Step S1: Prepare the analyte for calibration in water, dilute it to the required concentration, place the liquid analyte on a surface-enhanced Raman spectroscopy substrate, and analyze the changes in Raman spectral intensity of the analyte solution using a Raman spectrometer to plot Raman spectra of the same analyte at different concentrations; directly detect analyte molecules on a glass substrate to obtain spectra for comparison with the prepared substrate; randomly select 10 points on the substrate and obtain Raman spectra of the analyte to test its uniformity; after one week, detect the Raman spectrum of the same analyte to test its stability.

[0106] Step S2: Build a model from the spectrum obtained in S1. When detecting the unknown concentration of the same type of sample to be tested, the substance concentration analysis and detection of the analyte can be realized based on the spectral intensity curve in the obtained Raman spectrum.

[0107] like Figure 5 As shown, the thickness of the silver nanoparticles generated by the reaction has almost no effect on the results of the electric field simulation.

[0108] like Figure 6 As shown, when Raman-enhanced substrates electrochemically deposited with silver nitrate solutions of different concentrations (10mM, 20mM, 30mM) were tested, the Raman-enhanced substrate with a silver nitrate concentration of 20mM showed the best enhancement effect.

[0109] like Figure 7 As shown, multiple prepared SERS substrates were immersed in R6G solutions of different concentrations for 30 min. Afterward, the SERS substrates were removed and dried on a drying table for Raman detection. A 785 nm laser was used as the excitation wavelength, with a laser power of 30 mW, an integration time of 5 s, and two integrations. The signals were denoised and baselined using software. The result for each spectral line was the average of five sampling points at that concentration. Raman spectra were plotted, and the detection limit of the Raman substrate for R6G was determined. The detection limit was as low as 10. -12 M.

[0110] like Figure 8 , 9 As shown, the substrate was immersed in a solution with a concentration of 10... -5 After drying in a mol / L R6G solution for 30 minutes, the substrate was dried on a drying table. A 785nm laser was used as the excitation wavelength, with a laser power of 30mW, an integration time of 5s, and two integration cycles. Raman signals were measured at 10 randomly selected points, and a Raman waterfall plot was created. The relative standard deviation (RSD) calculated from the peak values ​​was 10.1%. The plot shows good substrate homogeneity.

[0111] like Figure 10 , 11 As shown in the Raman spectra of acetamiprid and carbendazim solid powders detected by the SERS microfluidic chip, the enhancement effect of the SERS microfluidic chip is significant.

[0112] like Figure 12 , 13 As shown, acetamiprid solid powder was dissolved in deionized water and methanol to prepare acetamiprid solutions of different concentrations. These solutions were then passed through multiple prepared microfluidic SERS chips for Raman detection. A 785 nm laser was used as the excitation wavelength, with a laser power of 30 mW, an integration time of 5 s, and two integrations. The signals were denoised and baselined using software. Each spectral line was the average of five sampling points at that concentration. The figure shows that the signal for detecting acetamiprid solution molecules is highest at 1580 cm⁻¹. -1 The standard characteristic peak at the concentration decreases gradually as the concentration decreases, showing a good linear relationship.

[0113] like Figure 14 , 15As shown, carbendazim solid powder was dissolved in deionized water and methanol to prepare carbendazim solutions of different concentrations. These solutions were then passed through multiple prepared microfluidic SERS chips for Raman detection. A 785nm laser was used as the excitation wavelength, with a laser power of 30mW, an integration time of 5s, and two integrations. The signals were denoised and baselined using software. Each spectral line was the average of five sampling points at that concentration. The figure shows that the signal for detecting acetamiprid solution molecules is highest at 1230 cm⁻¹. -1 The standard characteristic peak at the concentration decreases gradually as the concentration decreases, showing a good linear relationship.

[0114] like Figure 16 As shown, acetamiprid and carbendazim solid powders were dissolved in deionized water and methanol to prepare a mixed solution of acetamiprid and carbendazim at a specific concentration. The prepared microfluidic SERS chip was then irradiated with this mixed solution for Raman detection. A 785nm laser was used as the excitation wavelength, with a laser power of 30mW, an integration time of 5s, and two integrations. The signal was denoised and baselined using software. Each spectral line was the average of five sampling points at that concentration. In Raman spectroscopy, different substances produce different characteristic peaks, which is the fingerprint characteristic of Raman spectroscopy. The detection results show characteristic peaks representing carbendazim and acetamiprid, indicating that the device has a certain detection and differentiation effect on the mixed solution of carbendazim and acetamiprid.

[0115] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0116] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0117] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0118] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as it is used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0119] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for fabricating a SERS microfluidic chip, characterized in that, The SERS microfluidic chip includes an ERS substrate and a microfluidic chip. The SERS substrate is connected to the output channel of the microfluidic chip, and the input channel of the microfluidic chip is used to input the sample solution to be detected. The SERS substrate is a porous silicon carbide substrate. The method includes the following steps: SERS substrates and microfluidic chips were fabricated separately. The microfluidic chip is bonded to the SERS substrate and glass slide, and a liquid inlet and a liquid outlet are provided to obtain the SERS microfluidic chip. The SERS substrate is made of porous silicon carbide material and silver nanoparticles are prepared by electrochemical deposition and automatic adsorption of silver nanoparticles. The method for fabricating the SERS substrate includes: The pretreated porous silicon carbide wafers are immersed in silver nitrate solution; Add hydrogen peroxide solution to silver nitrate solution; Add PVP solution to silver nitrate solution; Silver nanoparticles were obtained by electrochemical deposition of sodium hydroxide solution into silver nitrate solution. A porous silicon carbide wafer automatically adsorbs silver nanoparticles to obtain a SERS substrate. The volume ratio of the hydrogen peroxide solution, sodium hydroxide solution, and silver nitrate solution is 1:1:1; The amount of PVP solution added is 0.8~1.5 ml; The preprocessing includes: The porous silicon carbide material is cut to obtain porous silicon carbide material sheets; The porous silicon carbide material sheet was sequentially cleaned of surface contaminants using hydrochloric acid, acetone, and ethanol solutions. The porous silicon carbide material sheet was cleaned of surface oxides using dilute sulfuric acid. The porous silicon carbide material sheet was washed with deionized water; Fix the cleaned porous silicon carbide material sheet and dry the surface with nitrogen gas.

2. The method for fabricating a SERS microfluidic chip according to claim 1, characterized in that, The method for fabricating the microfluidic chip includes: Design microfluidic channels for microfluidic chips; Silicon anode templates for chip fabrication using photolithography; Pour the prepared PDMS mixture into a culture dish with the silicon anodic template attached, remove air bubbles, and then place it in an oven for heating. The PDMS chip is peeled off with a cutting tool and cut into individual pieces to obtain a single-layer microfluidic chip.

3. The method for fabricating a SERS microfluidic chip according to claim 2, characterized in that: The microfluidic channel is a Y-shaped channel driven by capillary force. The microfluidic channel includes a main body section and two liquid inlet sections. The liquid inlet sections are symmetrically arranged at the front end of the main body section and communicate with the front end of the main body section. The end of the liquid inlet section is the liquid inlet, and the rear end of the main body section is the liquid outlet. The liquid outlet is connected to the SERS substrate groove below the microfluidic channel.

4. The method for fabricating a SERS microfluidic chip according to claim 3, characterized in that: The microfluidic channel is 12-15mm wide, 32-38mm long, and 1-3mm deep. The main body section and the liquid inlet section are 1-3mm wide. The SERS base groove is located at the bottom of the liquid inlet section of the microfluidic channel. The SERS base groove is a square groove with a side length of 7-9mm.

5. The method for fabricating a SERS microfluidic chip according to claim 1, characterized in that, The bonding of the microfluidic chip to the SERS substrate and glass slide includes: The SERS substrate storage area was cut out on a glass slide using CNC cutting technology; The prepared monolayer microfluidic chip and glass slide were ultrasonically cleaned with ethanol, and then dried with oxygen plasma. The SERS substrate is placed in the SERS substrate storage area on a glass slide, and the microfluidic chip is bonded to the glass slide.

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