Optofluidic raman sensing chip based on sers substrate and preparation method thereof

Abstract

The application belongs to the technical field of Raman spectrum analysis, and particularly relates to an optical flow Raman sensing chip based on a SERS substrate and a preparation method thereof. The optical flow Raman sensing chip comprises a first PDMS layer, a silicon-based optical waveguide layer and a second PDMS layer, wherein the silicon-based optical waveguide layer is arranged on the top surface of the first PDMS layer, the silicon-based optical waveguide layer has a top surface and two side surfaces, the second PDMS layer is arranged on the top surface and the side surfaces of the silicon-based optical waveguide layer, the surface of the side surface of the second PDMS layer facing the silicon-based optical waveguide layer is provided with a near-coaxial cavity, and the arc-shaped inner wall of the near-coaxial cavity is provided with a reflecting film. The target object solution is specifically combined with the SERS composite layer through the microfluidic channel, the SERS composite layer loaded with the target object generates Raman laser under the excitation of pump light, and the Raman laser is output after enhancement under the synergistic effect of the arc-shaped inner wall and the reflecting film. The application significantly improves the collection efficiency of the Raman signal through the multi-dimensional coupling enhancement effect of the cavity structure.

Description

Technical Field

[0001] This invention belongs to the field of Raman spectroscopy analysis technology, and particularly relates to an optically fluidized Raman sensor chip based on a SERS substrate and its fabrication method. Background Technology

[0002] Raman spectroscopy, due to its high sensitivity and molecular specificity, is widely used in biomolecule detection and environmental pollutant monitoring. However, the application of traditional Raman spectroscopy in complex liquid environments is limited, especially in the detection of low-concentration target analytes, where signal intensity is insufficient. Surface-enhanced Raman scattering (SERS) technology can significantly enhance the Raman signal through the localized surface plasmon resonance (LSPR) effect of metal nanoparticles, but the application of SERS technology in complex environments still faces challenges.

[0003] Existing SERS techniques typically rely on unidirectional excitation and signal collection, resulting in limited signal enhancement. Furthermore, background noise and interfering substances in complex liquid environments can also affect detection accuracy and sensitivity. Therefore, developing a Raman sensing method capable of achieving highly sensitive and rapid detection in complex liquid environments is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention aims to provide an optofluidic Raman sensor chip based on a SERS substrate and its fabrication method, to solve the problem that existing technologies typically rely on unidirectional excitation and signal collection, resulting in limited signal enhancement effects. The present invention significantly improves the Raman signal collection efficiency through the multidimensional coupling enhancement effect of the cavity structure.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0006] A photofluidic Raman sensor chip based on a SERS substrate includes a first PDMS layer, a silicon-based optical waveguide layer, and a second PDMS layer. The silicon-based optical waveguide layer is disposed on the top surface of the first PDMS layer and has a top surface and two side surfaces. The second PDMS layer is located on the top surface and side surfaces of the silicon-based optical waveguide layer. A near-concentric cavity is provided on the surface of the second PDMS layer facing the side surface of the silicon-based optical waveguide layer, and a reflective film is provided on the arc-shaped inner wall of the near-concentric cavity.

[0007] The silicon-based optical waveguide layer includes a silicon-based optical waveguide and a SERS composite layer. A microfluidic channel is formed in the second PDMS layer. The target solution containing the analyte binds specifically to the SERS composite layer through the microfluidic channel. When the SERS composite layer loaded with the target analyte is excited by pump light, it generates a Raman scattering signal. The Raman scattering signal is enhanced by the synergistic effect of the arc-shaped inner wall and the reflective film.

[0008] Furthermore, the silicon-based optical waveguide has a wedge-shaped structure, including a top surface and two side surfaces. The SERS composite layer is disposed on the top surface of the silicon-based optical waveguide, and the surface of the second PDMS layer facing the side surface of the silicon-based optical waveguide has a near-concentric cavity. The silicon-based optical waveguide extends along a first direction in the first PDMS layer.

[0009] Furthermore, the surface of the second PDMS layer facing the SERS composite layer is provided with a groove extending along the first direction. The groove is used to accommodate the SERS composite layer, so that the second PDMS layer is tightly bonded to the silicon-based optical waveguide layer.

[0010] Furthermore, the near-concentric cavities are arranged sequentially along the first direction, and the length of the major axis of the near-concentric cavity is twice the wavelength of the excitation laser.

[0011] Furthermore, the microfluidic channel is connected to the SERS composite layer. The microfluidic channel includes an inlet and an outlet arranged along a first direction. The inlet and outlet are located on the top surface of the second PDMS layer. The target solution is injected from the inlet and discharged from the outlet.

[0012] Furthermore, the microfluidic channels are arranged in a wave-like pattern.

[0013] Furthermore, graphene oxide and thiols are modified on the surface of silver nanoparticles to form a SERS composite layer.

[0014] A method for fabricating an optofluidic Raman sensor chip based on a SERS substrate, specifically including the following steps:

[0015] S1: Prepare the first PDMS layer;

[0016] S2: Silicon-based waveguide material is bonded to the upper surface of the first PDMS layer to form a silicon-based optical waveguide;

[0017] S3: A SERS composite layer is fabricated on the top surface of a silicon-based optical waveguide, and the SERS composite layer specifically binds to the analyte.

[0018] S4: Prepare a second PDMS layer with a near-concentric cavity, and set a reflective film on the arc-shaped inner wall of the near-concentric cavity;

[0019] S5: A microfluidic channel is opened in the second PDMS layer, and the microfluidic channel is connected to the SERS composite layer;

[0020] S6: Position the second PDMS layer on the top and side surfaces of the silicon-based optical waveguide layer to obtain an optically fluidized Raman sensor chip based on a SERS substrate.

[0021] Furthermore, in step S3, silver nanoparticles are prepared by chemical reduction, and graphene oxide and thiol substances are modified on the surface of the silver nanoparticles to form a SERS composite layer.

[0022] Furthermore, in step S3, a SERS composite layer is self-assembled on the top surface of the silicon-based optical waveguide using chemical bonding.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] This invention presents an optofluidic Raman sensor chip based on a SERS substrate and its fabrication method. By combining the SERS substrate with a silicon-based optical waveguide and introducing cavity structure enhancement technology, a multidimensionally coupled optofluidic Raman sensor chip is constructed, enabling highly sensitive and rapid detection of targets in complex liquid environments. This invention significantly improves the Raman signal collection efficiency through the multidimensional coupling enhancement effect of the cavity structure, making it suitable for fields such as marine environmental monitoring and biomedical detection. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 A perspective view of an optically fluidized Raman sensor chip based on a SERS substrate, which is an embodiment of the present invention;

[0027] Figure 2 A structural diagram of the second PDMS layer in an embodiment of the present invention;

[0028] Figure 3 A schematic flowchart illustrating the fabrication method of an optofluidic Raman sensor chip based on a SERS substrate, which is an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. First PDMS layer; 2. Silicon-based optical waveguide; 3. SERS composite layer; 4. Second PDMS layer; 4-1. Microfluidic channel; 4-2. Sample inlet; 4-3. Sample outlet; 4-4. Near-concentric cavity. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention 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, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] like Figures 1-2 As shown, the present invention provides an optical fluid Raman sensor chip based on a SERS substrate, comprising a first PDMS layer 1, a silicon-based optical waveguide layer, and a second PDMS layer 4. The silicon-based optical waveguide layer is disposed on the top surface of the first PDMS layer 1 and has a top surface and two side surfaces. The second PDMS layer 4 is located on the top surface and side surfaces of the silicon-based optical waveguide layer. The surface of the second PDMS layer 4 facing the side surface of the silicon-based optical waveguide layer is provided with a near-concentric cavity 4-4, and the arc-shaped inner wall of the near-concentric cavity 4-4 is provided with a reflective film.

[0037] The silicon-based optical waveguide layer includes a silicon-based optical waveguide 2 and a SERS composite layer 3. A microfluidic channel 4-1 is formed in the second PDMS layer 4. The target solution containing the analyte is specifically bound to the SERS composite layer 3 through the microfluidic channel 4-1. When the SERS composite layer 3 loaded with the target analyte is excited by pump light, a Raman scattering signal is generated. The Raman scattering signal is enhanced by the synergistic effect of the arc-shaped inner wall and the reflective film.

[0038] It should be noted that this invention constructs a multidimensionally coupled optofluidic Raman sensing chip by combining a surface-enhanced Raman scattering (SERS) substrate with an optical waveguide and introducing cavity structure enhancement technology. This chip can achieve highly sensitive and rapid detection of targets such as polycyclic aromatic hydrocarbons (PAHs) in complex liquid environments. This invention significantly improves the Raman signal collection efficiency through the multidimensional coupling enhancement effect of the cavity structure.

[0039] Furthermore, the SERS-based optical fluid Raman sensor chip includes a first PDMS layer 1 (bottom layer) and a second PDMS layer 4 (top layer), which are stacked with the intermediate silicon-based optical waveguide 2 and SERS composite layer 3, respectively, forming a sandwich-like layered structure.

[0040] The first PDMS layer 1 mainly serves as the substrate support for the optofluidic Raman sensor chip, playing a role in fixing the silicon-based optical waveguide 2 and enhancing the mechanical stability of the chip. At the same time, surface modification can optimize the adhesion with the silicon-based optical waveguide 2 to prevent interlayer delamination.

[0041] The second PDMS layer 4 is the functional core layer, which integrates microfluidic channels 4-1 for transporting the analyte solution, enabling precise delivery and enrichment of the solution on the surface of the SERS composite layer 3. A near-concentric cavity 4-4 is also fabricated within the surface, with a reflective film coated on its arc-shaped inner wall to reflect the Raman laser and improve signal collection efficiency. The second PDMS layer 4 serves as the top sealing layer for the entire microfluidic chip.

[0042] Furthermore, graphene oxide (GO) and thiols were modified on the surface of silver nanoparticles to form a SERS composite layer 3.

[0043] It should be noted that the SERS composite layer 3 can specifically bind to the target (such as polycyclic aromatic hydrocarbons PAHs) and enhance the Raman signal.

[0044] Specific binding refers to the precise and selective binding of the analyte to the SERS composite layer 3 based on molecular structure matching or biorecognition mechanisms, rather than non-specific physical adsorption or random binding. This effectively eliminates the influence of interfering substances in the sample matrix and avoids signal interference or false positive results caused by the adsorption of non-target substances on the surface of the SERS composite layer 3. It achieves trace enrichment: the analyte is directionally enriched in the "hotspot region" of the SERS composite layer 3 through specific binding, significantly improving the Raman signal intensity and meeting the needs of trace detection. It ensures detection accuracy: compared to non-specific adsorption, specific binding has higher affinity and more stable binding, reducing fluctuations in detection results and improving data repeatability and reliability.

[0045] Furthermore, the silicon-based optical waveguide 2 has a wedge-shaped structure, including a top surface and two side surfaces. The SERS composite layer 3 is disposed on the top surface of the silicon-based optical waveguide 2, and the surface of the second PDMS layer 4 facing the side surfaces of the silicon-based optical waveguide 2 has a near-concentric cavity 4-4. The silicon-based optical waveguide 2 is positioned along the first direction x of the first PDMS layer 1. Figure 1 (Extends in the x-direction).

[0046] Furthermore, the microfluidic channel 4-1 is connected to the SERS composite layer 3. The microfluidic channel 4-1 is arranged along the first direction x and includes an inlet 4-2 and an outlet 4-3. The inlet 4-2 and the outlet 4-3 are located on the top surface of the second PDMS layer 4. The target solution is injected from the inlet 4-2 and discharged from the outlet 4-3.

[0047] Furthermore, the microfluidic channels 4-1 are arranged in a wavy pattern to increase the contact area between the target solution and the SERS composite layer 3.

[0048] Furthermore, the analyte was a polycyclic aromatic hydrocarbon.

[0049] Furthermore, the surface of the second PDMS layer 4 facing the SERS composite layer 3 is provided with a groove extending along the first direction x. The groove is used to accommodate the SERS composite layer 3, so that the second PDMS layer 4 is tightly bonded to the silicon-based optical waveguide layer.

[0050] like Figure 3 As shown, this invention provides a method for fabricating an optofluidic Raman sensor chip based on a SERS substrate, which specifically includes the following steps:

[0051] S1: Prepare the first PDMS layer 1;

[0052] S2: Silicon-based waveguide material is bonded to the upper surface of the first PDMS layer 1 to form a silicon-based optical waveguide 2;

[0053] S3: A SERS composite layer 3 is prepared on the top surface of the silicon-based optical waveguide 2, and the SERS composite layer 3 specifically binds to the analyte.

[0054] S4: Prepare a second PDMS layer 4 with a near-concentric cavity 4-4, and set a reflective film on the arc-shaped inner wall of the near-concentric cavity 4-4;

[0055] S5: A microfluidic channel 4-1 is opened in the second PDMS layer 4, and the microfluidic channel 4-1 is connected to the SERS composite layer 3;

[0056] S6: Position the second PDMS layer 4 on the top and side surfaces of the silicon-based optical waveguide layer to obtain an optical fluidized Raman sensor chip based on a SERS substrate.

[0057] It should be noted that a portable Raman spectrometer is used to collect signals, and data analysis is used to achieve highly sensitive detection of the target object.

[0058] In some embodiments, the silicon-based optical waveguide 2 is a wedge-shaped structure. The optical field distribution on the surface of the silicon-based optical waveguide 2 is optimized through finite element simulation to ensure efficient interaction between the SERS composite layer 3 and the target object. In the SERS-based optofluidic Raman sensor chip, the shape of the wedge-shaped silicon-based optical waveguide 2 can precisely control the optical field distribution of the pump light, achieving local enhancement and mode constraint of the optical field in the region of the SERS composite layer 3, thereby improving the interaction efficiency between the target object and the optical field, and ultimately enhancing the excitation and collection effect of the Raman signal. The cross-section of the wedge-shaped silicon-based optical waveguide 2 has a gradually changing structure of "wide at one end and narrow at the other end". Compared with traditional planar waveguides or rectangular waveguides, its gradually changing refractive index boundary can guide the pump light to converge towards the narrow end of the wedge-shaped silicon-based optical waveguide 2 or a specific interface (the contact surface between the SERS composite layer 3 and the silicon-based optical waveguide 2) during propagation. Silicon itself has a high refractive index (approximately 3.48), which forms a significant refractive index difference with the upper and lower PDMS layers (approximately 1.41), allowing it to constitute the core and cladding structure of the silicon-based optical waveguide 2. The wedge-shaped design constrains the transmission mode of the pump light, suppressing scattering and leakage losses, ensuring the pump light is directionally transmitted along the silicon-based optical waveguide 2 to the SERS composite layer 3 region. The SERS composite layer 3 (such as a functional layer loaded with silver nanoparticles) is directly deposited on the surface of the wedge-shaped silicon-based optical waveguide 2. The inclined interface of the wedge increases the contact area between the SERS composite layer 3 and the light field, while simultaneously modulating the incident angle of the light field, allowing the pump light to be incident at a more optimal angle onto the "hot spots" between the nanoparticles, enhancing the localized surface plasmon resonance (LSPR) effect. This optimized interface coupling allows the light field energy to be transferred more efficiently to the analyte molecules, exciting stronger Raman scattering, forming a dual optical gain of "excitation-collection" with the subsequent reflection enhancement of the near-concentric cavity 4-4.

[0059] Furthermore, the material properties (refractive index, extinction coefficient, etc.) of the waveguide core and cladding are defined in the finite element simulation software, and geometric parameters such as core thickness, cross-sectional dimensions, and waveguide length are parameterized. The core parameters of the noble metal SERS composite layer 3 are transformed into simulation boundary conditions: the dielectric constant of the nanoparticles (correlated with the incident light wavelength, introducing the dispersion model of the metal material), particle size, and morphology (spherical, rod-shaped, star-shaped) are defined; the spatial distribution of the SERS composite layer 3 on the waveguide surface is set, including deposition density, arrangement, and interparticle spacing, while the interface contact model between the substrate and the waveguide surface is marked. Based on the finite element method, Maxwell's equations of the waveguide region are discretized and solved, and excitation conditions such as the wavelength, polarization state, and incident angle of the incident light are set, while the boundary type of the simulation is defined; through frequency domain or time domain simulation, the core data such as electric field intensity distribution, magnetic field distribution, and energy flux density of the waveguide surface and near-field region are output. The study focuses on extracting local optical field enhancement factors, locating the spatial coordinates and intensity magnitude of optical field "hot spots," and verifying the overlap between the hot spot region and the gaps between the 3-nanometer particles in the SERS composite layer. It analyzes the penetration depth of the optical field in the target adsorption layer to ensure that the optical field energy can effectively cover the target molecules, while statistically analyzing the energy ratio inside and on the surface of the waveguide to avoid excessive confinement of the optical field to the waveguide core layer, which could lead to surface energy loss. The coupling efficiency of surface plasmon polaritons (SPPs) is monitored, and simulation data is used to determine the effect of the waveguide surface micro / nanostructure on the excitation and propagation of SPPs, evaluating the synergy between plasmon enhancement and waveguide optical field confinement. Finally, simulations are used to determine experimental parameters and optimize the optical field distribution on the surface of silicon-based optical waveguide 2.

[0060] In some embodiments, in step S3, silver nanoparticles are prepared by chemical reduction, and graphene oxide and thiol substances are modified on the surface of the silver nanoparticles to form SERS composite layer 3.

[0061] In some embodiments, in step S3, a SERS composite layer 3 is self-assembled on the top surface of the silicon-based optical waveguide 2 using chemical bonding.

[0062] A near-concentric cavity 4-4 structure is embedded in a microfluidic chip, and cavity enhancement technology is used to achieve multidimensional coupling enhancement of the Raman signal. The microfluidic channel 4-1 and cavity structure are fabricated using femtosecond laser processing technology to ensure efficient interaction between the optical field and the fluid sample. The specific process is as follows: First, oil and impurities on the silicon-based optical waveguide 2 are removed by ultrasonic cleaning with anhydrous ethanol, followed by plasma treatment to remove impurities. A micro-reflective spherical cavity (i.e., near-concentric cavity 4-4, with its major axis length twice the wavelength of the excitation laser) is then fabricated along the axis of the silicon-based optical waveguide 2 using femtosecond processing technology. Subsequently, a high-reflectivity film is deposited inside the microgroove region using vacuum evaporation or magnetron sputtering. Finally, when the pump light field is transmitted through the silicon-based optical waveguide 2, the light field leakage excites sample molecules to generate Raman signals through the reflective spherical cavity (i.e., near-concentric cavity 4-4). The Raman signal is reflected and coupled into the interior of the silicon-based optical waveguide 2 through the reflective spherical cavity (i.e., near-concentric cavity 4-4) for transmission, and finally transmitted by the silicon-based optical waveguide 2 to the Raman spectrometer for analysis.

[0063] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0064] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A photofluidic Raman sensor chip based on a SERS substrate, characterized in that: It includes a first PDMS layer, a silicon-based optical waveguide layer, and a second PDMS layer. The silicon-based optical waveguide layer is disposed on the top surface of the first PDMS layer and has a top surface and two side surfaces. The second PDMS layer is located on the top surface and side surfaces of the silicon-based optical waveguide layer. The surface of the second PDMS layer facing the side surface of the silicon-based optical waveguide layer is provided with a near-concentric cavity, and the arc-shaped inner wall of the near-concentric cavity is provided with a reflective film. The silicon-based optical waveguide layer includes a silicon-based optical waveguide and a SERS composite layer. A microfluidic channel is formed in the second PDMS layer. The target solution containing the analyte binds specifically to the SERS composite layer through the microfluidic channel. When the SERS composite layer loaded with the target analyte is excited by pump light, it generates a Raman scattering signal. The Raman scattering signal is enhanced by the synergistic effect of the arc-shaped inner wall and the reflective film.

2. The SERS-based optofluidic Raman sensor chip according to claim 1, characterized in that: The silicon-based optical waveguide has a wedge-shaped structure, including a top surface and two side surfaces. A SERS composite layer is disposed on the top surface of the silicon-based optical waveguide, and a near-concentric cavity is provided on the surface of the second PDMS layer facing the side surfaces of the silicon-based optical waveguide. The silicon-based optical waveguide extends along a first direction in the first PDMS layer.

3. The SERS-based optofluidic Raman sensor chip according to claim 2, characterized in that: The surface of the second PDMS layer facing the SERS composite layer has a groove extending along the first direction. The groove is used to accommodate the SERS composite layer, so that the second PDMS layer is tightly bonded to the silicon-based optical waveguide layer.

4. The SERS-based optofluidic Raman sensor chip according to claim 2, characterized in that: The near-concentric cavities are arranged sequentially along the first direction, and the length of the major axis of the near-concentric cavity is twice the wavelength of the excitation laser.

5. The SERS-based optofluidic Raman sensor chip according to claim 2, characterized in that: The microfluidic channel is connected to the SERS composite layer. The microfluidic channel includes an inlet and an outlet arranged along a first direction. The inlet and outlet are located on the top surface of the second PDMS layer. The target solution is injected from the inlet and discharged from the outlet.

6. The SERS-based optofluidic Raman sensor chip according to claim 1, characterized in that: The microfluidic channels are arranged in a wave-like pattern.

7. The SERS-based optofluidic Raman sensor chip according to claim 1, characterized in that: Graphene oxide and thiols are modified on the surface of silver nanoparticles to form a SERS composite layer.

8. A method for fabricating an optofluidic Raman sensor chip based on a SERS substrate, used to fabricate the optofluidic Raman sensor chip based on a SERS substrate as described in claim 1, characterized in that: Specifically, the steps include the following: S1: Prepare the first PDMS layer; S2: A silicon-based waveguide material is attached to the upper surface of the first PDMS layer to form a silicon-based optical waveguide; S3: A SERS composite layer is fabricated on the top surface of a silicon-based optical waveguide, and the SERS composite layer specifically binds to the analyte. S4: Prepare a second PDMS layer with a near-concentric cavity, and provide a reflective film on the arc-shaped inner wall of the near-concentric cavity; S5: A microfluidic channel is formed within the second PDMS layer, and the microfluidic channel is connected to the SERS composite layer; S6: Position the second PDMS layer on the top and side surfaces of the silicon-based optical waveguide layer to obtain an optically fluidized Raman sensor chip based on a SERS substrate.

9. The method for fabricating an optofluidic Raman sensor chip based on a SERS substrate according to claim 8, characterized in that: In step S3, silver nanoparticles are prepared by chemical reduction, and graphene oxide and thiols are modified on the surface of the silver nanoparticles to form a SERS composite layer.

10. The method for fabricating an optofluidic Raman sensor chip based on a SERS substrate according to claim 8, characterized in that: In step S3, a SERS composite layer is self-assembled on the top surface of the silicon-based optical waveguide using chemical bonding.

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