A surface-enhanced Raman optofluidic chip based on planar waveguide microfluidic structure

Abstract

The present invention claims protection for a surface enhanced Raman optofluidic chip based on a flat waveguide microfluidic structure, which comprises: a flat waveguide, a microfluidic structure and a silicon substrate, wherein the flat waveguide comprises a waveguide upper cladding, a waveguide lower cladding and a waveguide core layer; the microfluidic structure comprises a liquid inlet channel, a liquid outlet channel and a microfluidic channel; the microfluidic channel is stacked on the upper surface of the waveguide upper cladding, and the liquid inlet channel and the liquid outlet channel are both arranged on the upper surface of the microfluidic channel; the silicon substrate is placed below the waveguide lower cladding; the waveguide core layer is arranged between the waveguide lower cladding and the waveguide upper cladding, and incident light is injected from the waveguide core layer or the microchannel and emitted from the other end of the waveguide core layer or the microchannel; the liquid inlet channel and the liquid outlet channel are placed in parallel above the microfluidic channel.

Description

Technical Field

[0001] The invention belongs to the field of optics and microfluidics, and relates to a surface enhanced Raman optofluid chip based on planar waveguide microfluids. Background Art

[0002] In recent years, the combination of surface-enhanced spectroscopy technology and microfluidics technology has been a major development trend in biochemical detection chips. Surface-enhanced Raman spectroscopy is an important optical detection method. It amplifies and enhances the Raman signal of the sample under test through the local field formed on the surface of the rough nanometal structure. By analyzing the SERS peak and intensity, the internal structure information at the molecular level can be obtained. This detection method can achieve rapid detection of samples without the need to label biological samples. Therefore, surface-enhanced Raman spectroscopy is particularly suitable for biochemical analysis. Taking advantage of the small volume of microfluidic channels, low-concentration samples can be detected, providing an important means for biochemical detection. At present, surface-enhanced Raman spectroscopy is widely used in food safety, biological sciences, drug analysis, water body detection and other fields.

[0003] At present, SERS detection technology mainly focuses on single-point detection. Although it is possible to enhance the SERS signal by increasing the concentration of the sample being detected and improving the structure of metal nanoparticles, the scope of biological samples participating in signal detection is extremely limited when performing single-point detection, and the distribution of the molecules and metal nanoparticles required to be detected in the biological sample solution is often uneven, resulting in poor repeatability of single-point detection and fluctuation of the detected signal. In addition, because the laser power used in single-point detection is high, direct irradiation of the sample being tested can easily damage the biological sample, and even make it impossible to detect the Raman signal of the sample.

[0004] Another means of SERS signal detection is long-range detection. By designing and manufacturing a waveguide structure, the laser is transmitted in the waveguide, which not only avoids direct irradiation of the sample being tested, but also effectively increases the detection volume of the sample. Combined with the nano-metal structure, long-range detection can not only enhance the SERS signal and avoid damage to biological samples, but also improve the signal detection repeatability. In addition, the use of polymers for the production of planar waveguides uses low-cost materials, simple processing and manufacturing processes, and the size can be accurately controlled, which is conducive to the integration and miniaturization of planar waveguides. Therefore, the SERS substrate based on polymer planar waveguides has a very broad research and application prospect.

[0005] CN108693160B, a surface enhanced Raman optofluid chip based on long-range plasma waveguide, comprising a coupling grating (1), a dielectric waveguide, a surface plasma waveguide, a microfluid structure and a silicon substrate (2); the dielectric waveguide is composed of a waveguide upper cladding (3), a waveguide lower cladding (4) and a waveguide core (5); the waveguide upper cladding (3) is arranged on the upper surface of the waveguide core (5), the coupling grating (1) is distributed on the upper surface of the waveguide core (5), and the coupling grating (1) is not in contact with the waveguide upper cladding (3); the outer surfaces of the silicon substrate (2), the waveguide lower cladding (4) and the waveguide core (5) are flush, and the outer surfaces of the waveguide upper cladding (3), the surface plasma waveguide core (9) and the microfluid channel (8) are flush. The surface enhanced Raman optofluid chip based on long-range plasma waveguide of the present invention has a simple structure and a small size, and an array structure can be manufactured on a single chip to improve detection sensitivity.

[0006] This patent adds a layer of plasma waveguide on the dielectric waveguide. Plasma waveguide requires an angle for excitation and has requirements on the angle of incident light. Therefore, this patent uses a coupling grating for waveguide coupling, and light needs to be incident from a fixed angle and direction.

[0007] The structure of this patent is simpler, directly using a planar waveguide for waveguide coupling, using local plasma to enhance the Raman signal, and has no requirements for the angle of the incident light.

[0008] CN111135891A, a grating waveguide microfluidic chip, including a grating waveguide and a microchannel, the grating waveguide includes an exit grating, the exit grating is located below the microchannel to guide light upward into the microchannel in a vertical direction, and also includes: a lower cladding, a waveguide layer, a protective layer and an upper cladding arranged from bottom to top; the protective layer is used to cover the grating waveguide and protect the exit grating; the microchannel runs through the upper cladding to expose the protective layer; the lower cladding and the upper cladding are both polymer materials with a thickness of 15 to 30 μm. It has beneficial effects: a silicon nitride film with adjustable optical properties is deposited on a flexible substrate, the application range and form of SiN optical device materials are expanded, the traditional optical system is realized by integrated optics or on-chip optical devices, the traditional desktop large optical system is reduced to chip size, excellent analytical performance is guaranteed, and a high-throughput chip-level optical detection and analysis integrated system of biological samples at micro-nano scale is realized, and the system cost is greatly reduced.

[0009] This patent uses a grating waveguide for waveguide coupling, and the incident light needs to be incident from a vertical direction.

[0010] This patent is applied to Raman detection, with a simpler structure and a long-range detection method. The light is incident from a horizontal direction, and the evanescent field generated at the interface of the waveguide core and the biological sample solution is used to excite the nearby precious metal plasma, thereby enhancing the Raman signal. It can also avoid damage to the biological sample and improve the signal detection repeatability. Summary of the invention

[0011] The present invention aims to solve the above problems of the prior art. A surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure is proposed. The technical solution of the present invention is as follows:

[0012] A surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure comprises: a planar waveguide, a microfluidic structure and a silicon substrate, wherein the planar waveguide comprises a waveguide upper cladding, a waveguide lower cladding and a waveguide core layer; the microfluidic structure comprises a liquid inlet channel, a liquid outlet channel and a microfluidic channel; the microfluidic channel is stacked and arranged on the upper surface of the waveguide upper cladding, and the liquid inlet channel and the liquid outlet channel are both arranged on the upper surface of the microfluidic channel; the silicon substrate is placed below the waveguide lower cladding; the waveguide core layer is arranged between the waveguide lower cladding and the waveguide upper cladding, and the incident light is injected from the waveguide core layer or the microchannel and emitted from the other end of the waveguide core layer or the microchannel; the liquid inlet channel and the liquid outlet channel are placed in parallel above the microfluidic channel;

[0013] The silicon substrate is used as a chip substrate, the refractive index of the waveguide lower cladding is lower than that of the waveguide core layer, forming total reflection, the waveguide core layer is a transmission channel for light, the refractive index of the waveguide upper cladding is lower than that of the waveguide core layer, forming a total reflection microfluidic channel for detecting the flow of liquid, the liquid inlet channel is used to detect the inflow of liquid, and the liquid outlet channel is used to detect the outflow of liquid.

[0014] Furthermore, the waveguide upper cladding is a noble metal nanostructure.

[0015] Furthermore, the noble metal includes gold, silver, and copper, and the nanostructures are spherical particles, square particles, or rod-shaped particles.

[0016] Furthermore, the liquid inlet channel and the liquid outlet channel are parallel to each other and symmetrically arranged above the microfluidic channel, and are perpendicular to the microfluidic channel.

[0017] Furthermore, the material of the waveguide core layer is polydimethylsiloxane (PDMS), and the material of the waveguide lower cladding layer is perfluoro 1-butenyl vinyl ether (CYTOP).

[0018] Furthermore, the material of the waveguide lower cladding is perfluoro-1-butenyl vinyl ether (CYTOP).

[0019] Furthermore, the material of the microfluidic channel is a PDMS film.

[0020] The advantages and beneficial effects of the present invention are as follows:

[0021] 1. The surface-enhanced Raman optofluidic chip based on the planar waveguide microfluidic structure of the present invention uses a long-range waveguide to extend the action distance between light and sample molecules, effectively enhancing the signal intensity;

[0022] 2. The present invention utilizes the averaging effect provided by the microfluidic structure, reduces the dependence on the surface enhanced Raman scattering substrate, and improves the signal repeatability;

[0023] 3. The surface-enhanced Raman optofluidic chip based on the planar waveguide microfluidic structure of the present invention has a simple structure and a small size. An array structure can be made on a single chip to improve detection sensitivity, and can realize the detection of low-concentration samples, providing an important means for biochemical detection.

[0024] 4. The surface-enhanced Raman optofluidic chip based on the planar waveguide microfluidic structure of the present invention can use two different detection methods and obtain detection signals without damaging the detection sample.

[0025] The innovation of the present invention is mainly to design a surface enhanced Raman substrate, combining a planar waveguide including a waveguide upper cladding (4), a waveguide lower cladding (2) and a waveguide core layer (3) with a microfluidic channel including a liquid inlet channel (6), a liquid outlet channel (7) and a microfluidic channel (5). Advantages: simple structure, easy to make, can avoid damage to the detected sample, and can improve the repeatability of surface enhanced Raman detection of samples. The present invention uses a planar waveguide for optical waveguide coupling. When light is totally reflected in the planar waveguide, an evanescent field is generated at the interface of the waveguide core-biological sample solution, thereby exciting nearby noble metal plasma, thereby achieving the effect of enhancing the Raman signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a front view of a chip according to a preferred embodiment of the present invention;

[0027] Figure 2 It is a top view of the chip of the present invention.

[0028] Figure 3 It is a schematic diagram of waveguide coupling of the chip of the present invention. DETAILED DESCRIPTION

[0029] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention.

[0030] The technical solution of the present invention to solve the above technical problems is:

[0031] like Figures 1 to 3As shown, the present invention is a surface enhanced Raman optofluidic chip based on a flat waveguide microfluidic structure, which is mainly composed of a flat waveguide, a microfluidic structure and a silicon substrate 1; the flat waveguide is composed of a waveguide upper cladding 4, a waveguide lower cladding 2 and a waveguide core 3; the microfluidic structure is composed of a liquid inlet channel 6, a liquid outlet channel 7 and a microfluidic channel 5; the microfluidic channel 5 is stacked on the upper surface of the waveguide upper cladding 4, and the liquid inlet channel 6 and the liquid outlet channel 7 are both arranged on the upper surface of the microfluidic channel 5; the silicon substrate 1 is placed below the waveguide lower cladding 2; the incident light is injected from the waveguide core 3 or the microchannel 5 and emitted from the other end of the waveguide core 3 or the microchannel 5.

[0032] The liquid inlet channel 6 and the liquid outlet channel 7 are placed in parallel above the microfluidic channel 5 and are perpendicular to the microfluidic channel 5 .

[0033] The material of the waveguide upper cladding layer 4 is a noble metal nanostructure.

[0034] The material of the waveguide core layer 3 is polydimethylsiloxane PDMS, and the material of the lower cladding layer 2 is perfluoro 1-butenyl vinyl ether CYTOP.

[0035] The present invention has two detection methods. The first method is to use a multi-layer planar waveguide structure for long-range detection, where the excitation light is totally reflected in the waveguide core layer 3 for light propagation, rather than directly irradiating the biological sample solution, to avoid damage to the biological sample. The schematic diagram is shown in FIG. Figure 3 The second method is to directly propagate the excitation light in the biological sample solution in the microfluidic channel 5, thereby obtaining the Raman signal of the biological sample.

[0036] Working principle: The detection liquid flows into the microfluidic channel 5 from the liquid inlet channel 6 and flows out from the liquid outlet channel 7. The incident light enters from the waveguide core layer 3 and is totally reflected at the interface between the waveguide upper cladding layer 4 and the waveguide lower cladding layer 2, generating an evanescent field, thereby exciting the noble metal plasma in the waveguide upper cladding layer 4, thereby enhancing the Raman signal. The enhanced Raman signal is emitted from the other end of the waveguide core layer 3.

[0037] Innovation of the present invention

[0038] The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure of the present invention has a simple structure and a small size, can be used repeatedly, and improves the repeatability of the SERS detection technology.

[0039] The surface enhanced Raman optofluidic chip based on the planar waveguide microfluidic structure of the present invention can use two different detection methods and can obtain detection signals without damaging the detection sample.

[0040] The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure of the present invention adopts a long-range detection method to allow the laser to be transmitted in the waveguide, which not only avoids direct irradiation of the sample to be tested, but also effectively increases the detection volume of the sample, thereby enhancing the SERS signal.

[0041] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0042] The above embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents of the present invention, technicians can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A surface-enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure, characterized in that: include: A planar waveguide, a microfluidic structure and a silicon substrate (1), wherein the planar waveguide comprises a waveguide upper cladding (4), a waveguide lower cladding (2) and a waveguide core layer (3); the microfluidic structure comprises a liquid inlet channel (6), a liquid outlet channel (7) and a microfluidic channel (5); the microfluidic channel (5) is stacked and arranged on the upper surface of the waveguide upper cladding (4), and the liquid inlet channel (6) and the liquid outlet channel (7) are both arranged on the upper surface of the microfluidic channel (5); the silicon substrate (1) is placed below the waveguide lower cladding (2); the waveguide core layer (3) is arranged between the waveguide lower cladding (2) and the waveguide upper cladding (4), and incident light is incident from the waveguide core layer (3) and is emitted from the other end of the waveguide core layer (3); the liquid inlet channel (6) and the liquid outlet channel (7) are placed in parallel above the microfluidic channel (5); The silicon substrate (1) is used as a chip substrate, the waveguide lower cladding (2) has a lower refractive index than the waveguide core layer, forming total reflection, and the waveguide core layer (3) is a light transmission channel, the waveguide upper cladding (4) has a lower refractive index than the waveguide core layer, forming total reflection, the microfluidic channel (5) is used to detect the flow of liquid, the liquid inlet channel (6) is used to detect the inflow of liquid, and the liquid outlet channel (7) is used to detect the outflow of liquid.

2. The surface-enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 1, characterized in that: The waveguide upper cladding (4) is a noble metal nanostructure.

3. The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 2, characterized in that: The noble metal includes gold, silver or copper, and the nanostructures are spherical particles, square particles or rod-shaped particles.

4. The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 1, characterized in that: The liquid inlet channel (6) and the liquid outlet channel (7) are parallel to each other and are symmetrically arranged above the microfluidic channel (5), and are perpendicular to the microfluidic channel (5).

5. The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 1, characterized in that: The material of the waveguide core layer (3) is polydimethylsiloxane (PDMS), and the material of the waveguide lower cladding layer (2) is perfluoro 1-butenyl vinyl ether (CYTOP).

6. The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 1, characterized in that: The material of the waveguide lower cladding (2) is perfluoro 1-butenyl vinyl ether CYTOP.

7. The surface enhanced Raman optofluidic chip based on a planar waveguide microfluidic structure according to claim 1, characterized in that: The material of the microfluidic channel (5) is a polydimethylsiloxane (PDMS) film.

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