Tapered periodic array structure SERS (Surface Enhanced Raman Scattering) sensing chip and preparation method and application thereof

Abstract

The invention provides an SERS (Surface Enhanced Raman Scattering) sensing chip with a conical periodic array structure as well as a preparation method and application of the SERS sensing chip. The SERS sensing chip with the conical periodic array structure comprises a conical periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer which are sequentially stacked. The SERS sensor chip has the advantages of high enhancement performance, high detection sensitivity, uniform detection signals and the like, and is widely applied to the fields of environment detection, food safety, industrial production, human health detection and the like.

Description

Technical Field

[0001] This invention belongs to the field of SERS sensor technology, and relates to a cone-shaped periodic array structure SERS sensor chip, its fabrication method and application. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) is a highly sensitive analytical method developed from traditional Raman spectroscopy. SERS sensors are used in numerous fields, including environmental monitoring, food safety, industrial production, and human health monitoring. To achieve SERS sensors with high detection sensitivity and high reproducibility, it is necessary to develop novel SERS sensor chips by focusing on the intrinsic electromagnetic field enhancement mechanism and employing three-dimensional structural tailoring.

[0003] For SERS sensors based on the LSPR (Local Plasmon Resonance Phosphorus) enhancement mechanism, nanoparticle systems typically require nanoscale gaps as narrow as 5 nm or even smaller to achieve significant electromagnetic field enhancement. However, as the gap size decreases drastically, not only is it difficult for analyte molecules to reach the "hot spot" gap due to steric hindrance, but the gap size cannot be reduced indefinitely due to limitations in fabrication methods. This restricts further improvements in the enhancement performance and practical applications of LSPR-based SERS sensors.

[0004] Surface-propagating plasmons (SPPs), the electromagnetic field enhancement mechanism of SERS, propagate along the interface of the metallic medium. They have a large spatial scale of influence and exhibit high geometric dependence and tunability. SPPs require coupling with LSPRs to achieve a sufficiently strong SERS effect. Therefore, they can completely overcome the bottleneck of SERS chips that rely solely on LSPRs, achieving a sufficiently strong SERS effect without pursuing extremely small gap sizes. This will significantly reduce the fabrication difficulty of SERS sensor chips and the size limitations of the analyte, thereby promoting their practical applications. However, SPPs typically require specialized excitation structures such as prisms, gratings, and topological defects before coupling with LSPRs, and currently, both excitation and coupling efficiencies are relatively low.

[0005] Therefore, there is an urgent need to develop new three-dimensional SERS sensor chips, that is, to use new effects / mechanisms to further improve the excitation and coupling efficiency of SPP, thereby significantly improving the performance of SERS sensor chips. Summary of the Invention

[0006] The purpose of this invention is to provide a cone-shaped periodic array structure SERS sensor chip, its fabrication method and application. The SERS sensor chip has advantages such as high enhancement performance, high detection sensitivity and uniform detection signal, and has wide applications in environmental monitoring, food safety, industrial production and human health monitoring.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a cone-shaped periodic array structure SERS sensing chip, the cone-shaped periodic array structure SERS sensing chip comprising a cone-shaped periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer stacked sequentially.

[0009] The SERS sensor chip with a conical periodic array structure described in this invention improves the periodic array structure by using a metal layer shaped on a conical periodic array structure substrate. This allows the metal layer with a special geometric structure to achieve SPP effect modulation. The hollowed-out dielectric layer creates nano gaps to enhance the LSPR effect and couple it with the SPP effect. The metal nanoparticle layer simultaneously creates a second mode of LSPR effect. Thus, the SERS sensor greatly improves its enhancement performance and detection sensitivity through the mutual coupling of multiple effects.

[0010] Specifically, the cone-shaped periodic array structure SERS sensing chip of the present invention includes multiple three-dimensional pyramidal array unit structures. That is, the present invention proposes a three-dimensional pyramidal array structure (such as a pyramid) with sharp tips and sharp edges, and a unique SERS chip configuration based on this structure, which consists of multiple layers of metal layers, hollow dielectric layers and metal nanoparticles stacked together. It is possible to develop SERS sensing chips with new enhancement effects / mechanisms based on this special configuration / structure.

[0011] This invention utilizes a pyramidal structure to efficiently excite SPP (Sparkling Polymer Propagation) in situ at its sharp tip, allowing it to propagate within a confined area along the edges, achieving energy concentration and efficient collection. The SPP propagating at the interface between the metal film and the perforated dielectric layer interferes with and reinforces the SPP waves reflected from the bottom metal film between the pyramidal structural units. Furthermore, this structure contains two types of LSPR (Laser-Sensitive Periodic Resonance Arrays): LSPR1 between metal nanoparticles and LSPR2 between metal particles and the metal layer. Both types of LSPRs can couple with the aforementioned SPP. Therefore, the cone-shaped periodic array structure proposed in this invention significantly improves the SERS effect using this novel enhancement mechanism, exhibiting advantages such as high detection sensitivity and uniform detection signal, and can be widely applied in environmental monitoring, food safety, industrial production, and human health monitoring.

[0012] The perforated dielectric layer of the present invention contains multiple dielectric units, which are spaced apart on the metal layer, thereby exposing the metal layer.

[0013] In the metal nanoparticle layer of the present invention, the metal nanoparticles correspond one-to-one with the dielectric units in the hollowed-out dielectric layer and are located at the upper end of the dielectric units. Therefore, there are also gaps between the metal nanoparticles, thus allowing the metal layer to be exposed.

[0014] Preferably, in the conical periodic array structure substrate, the conical structure is a pyramidal conical structure.

[0015] Preferably, the angle between the side surface and the bottom surface of the conical structure is 30-85°, for example, it can be 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80° or 85°, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 50-70°.

[0016] In the conical structure of this invention, the angle between the side surface and the bottom surface, i.e. the bottom angle of the three-dimensional pyramid structure, affects the detection sensitivity and other performance of the SERS sensor chip. If the angle between the side surface and the bottom surface of the conical structure is too small, the SPP excitation efficiency will decrease, resulting in a decrease in SERS enhancement performance. If the angle between the side surface and the bottom surface of the conical structure is too large, it cannot be obtained by this processing method, and the SPP effect loss will be too large, resulting in a decrease in SERS enhancement performance.

[0017] Preferably, the base length of the conical structure is 300-10000nm, for example, it can be 300nm, 500nm, 1000nm, 4000nm, 6000nm, 8000nm or 10000nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] The base length of the cone-shaped structure described in this invention is the same as the base length of the three-dimensional pyramid structure.

[0019] Preferably, the thickness of the metal layer is 50nm-400nm, for example, it can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm or 400nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the thickness of the perforated dielectric layer is 0.5-10nm, for example, it can be 0.5nm, 2nm, 2.5nm, 5nm, 7.5nm or 10nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1-5nm.

[0021] If the thickness of the perforated dielectric layer described in this invention is too small, the molecules to be tested will have difficulty entering the narrow space, resulting in poor SERS enhancement performance. Furthermore, if the thickness is too small, the LSPR2 effect between the metal particles and the metal layer will weaken, also leading to reduced enhancement performance. If the thickness of the perforated dielectric layer described in this invention is too large, the LSPR2 effect between the metal nanoparticles and the metal layer will almost disappear, resulting in weakened enhancement performance.

[0022] Preferably, the diameter of the metal nanoparticles in the metal nanoparticle layer is 10-180 nm, for example, it can be 10 nm, 40 nm, 70 nm, 100 nm, 130 nm, 160 nm or 180 nm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 20-100 nm.

[0023] If the diameter of the metal nanoparticles in the metal nanoparticle layer of this invention is too small, the LSPR effect will be weak, resulting in poor reinforcement performance. If the diameter of the metal nanoparticles in the metal nanoparticle layer is too large, on the one hand, it is not easy to prepare by the annealing process in the processing method of this invention; on the other hand, the density of the metal nanoparticles decreases sharply, resulting in a weakened LSPR effect and thus poor reinforcement performance.

[0024] Preferably, the conical periodic array structure substrate includes any one or a combination of at least two of the following: silicon substrate, silicon oxide substrate, sapphire, PDMS (polydimethylsiloxane) flexible substrate, or silver substrate.

[0025] Preferably, the metal layer comprises a plasmonic metal material.

[0026] Preferably, the perforated dielectric layer includes any one or a combination of at least two of silicon oxide, molybdenum disulfide, aluminum oxide, titanium oxide, or silicon carbide. Typical but not limited combinations include a combination of silicon oxide and aluminum oxide, a combination of molybdenum disulfide and titanium oxide, or a combination of aluminum oxide, titanium oxide, and silicon carbide.

[0027] Preferably, the metal nanoparticles in the metal nanoparticle layer comprise plasmonic metal materials.

[0028] Preferably, the plasmonic metallic material includes any one or a combination of at least two of gold, silver, copper, platinum or palladium. Typical but not limited combinations include combinations of gold and silver, copper and platinum, or gold, platinum and palladium.

[0029] In a second aspect, the present invention provides a method for fabricating a SERS sensor chip with a conical periodic array structure as described in the first aspect, the method comprising the following steps:

[0030] A metal layer, a hollow dielectric layer, and a metal nanoparticle layer are sequentially fabricated on the surface of a cone-shaped periodic array structure substrate to obtain the cone-shaped periodic array structure SERS sensing chip.

[0031] Preferably, the method for preparing the conical periodic array structure substrate includes any one or a combination of at least two of the following steps (A), (B), (C), or (D):

[0032] (A) Coating an etchant onto the substrate surface, and obtaining the cone-shaped periodic array structure substrate through exposure, development, fixing and etching;

[0033] (B) The conical periodic array structure substrate is prepared on the substrate surface by using a film tool and a nanoimprint method;

[0034] (C) A monolayer of microspheres is coated on the substrate surface. Using the monolayer of microspheres as a mask, a wet etching process is used to obtain the cone-shaped periodic array structure substrate.

[0035] (D) A positive photoresist is coated on the substrate surface, and the cone-shaped periodic array structure substrate is obtained by exposure, development, fixing, evaporation of a hard mask, stripping and etching.

[0036] Preferably, the substrate described in steps (A), (B), (C), and (D) is cleaned before use.

[0037] Preferably, the cleaning process includes immersing the substrate in isopropanol, ultrasonically cleaning it, and then removing it and drying it with nitrogen; then immersing the substrate in acetone, ultrasonically cleaning it, and then removing it and drying it with nitrogen.

[0038] Preferably, the exposure in step (A) includes optical exposure or electron beam exposure;

[0039] Preferably, the coating method described in steps (A), (C), and (D) includes spin coating.

[0040] Preferably, the method for preparing the metal layer includes any one or a combination of at least two of electron beam evaporation, magnetron sputtering, or chemical vapor deposition.

[0041] Preferably, the method for preparing the hollowed-out dielectric layer includes any one or a combination of at least two of electron beam evaporation, physical vapor deposition, chemical vapor deposition, or atomic layer deposition.

[0042] Preferably, the method for preparing the metal nanoparticle layer includes any one or a combination of at least two of electron beam evaporation, magnetron sputtering, chemical vapor deposition, or atomic layer deposition.

[0043] When preparing the metal particle layer in this invention, a thin metal layer can be deposited by vapor deposition and then annealed to obtain the metal nanoparticle layer; alternatively, the metal nanoparticle layer can be obtained by self-assembly, using the metal nanoparticles as a mask, and BOE vapor etching to create a hollowed-out dielectric layer, ultimately producing a cone-shaped periodic array structure SERS sensor chip.

[0044] Thirdly, the present invention provides an application of the cone-shaped periodic array structure SERS sensing chip as described in the first aspect, the application including the application of high-sensitivity detection of trace molecules.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The chip provided by this invention improves the three-dimensional structure by using a cone-shaped periodic array structure substrate to shape the metal layer with a special geometric structure to achieve SPP effect modulation, and the hollow dielectric layer creates nano gaps to achieve LSPR effect enhancement and coupling with the SPP effect. The metal nanoparticle layer simultaneously creates a second mode of LSPR effect. Through the multi-effect coupling of SPP and LSPR, the enhancement performance of the SERS sensor is improved, thus giving the SERS sensor chip advantages such as high enhancement performance, high detection sensitivity and uniform detection signal. It can be widely used in environmental monitoring, food safety, industrial production and human health monitoring. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the SERS sensor chip with a conical periodic array structure as described in Embodiment 1 of the present invention;

[0048] Figure 2 This is a schematic diagram of the fabrication process of the cone-shaped periodic array structure SERS sensor chip described in Embodiment 1 of the present invention;

[0049] Figure 3 Schematic diagram of the enhancement mechanism of the cone-shaped periodic array structure SERS sensor chip described in Embodiment 1 of the present invention;

[0050] Figure 4 This is a SEM image of the cone-shaped periodic array structure SERS sensing chip described in Embodiment 1 of the present invention;

[0051] Figure 5 The SERS sensor chip described in Embodiment 1 and Comparative Example 1 of the present invention is used for a concentration of 10 -8 Raman spectroscopy of M in 4-MPBA (4-mercaptophenylboronic acid) solution;

[0052] Figure 6 The SERS sensor chip described in Embodiment 2 and Comparative Example 2 of this invention is suitable for a concentration of 10. -7 Raman spectroscopy of M in 4-MPBA solution;

[0053] Figure 7 The SERS sensor chip described in Embodiment 3 and Comparative Example 3 of this invention is suitable for a concentration of 10. -6 Raman spectroscopy of M's R6G (Rhodamine 6G) solution;

[0054] Figure 8 The SERS sensor chip described in Embodiments 4 and 10 of this invention is suitable for a concentration of 10. -6 Raman spectroscopy of M's R6G solution;

[0055] Figure 9 The SERS sensor chip described in Embodiments 5 and 12 of this invention is suitable for a concentration of 10. -6 Raman spectroscopy of M's R6G solution;

[0056] Figure 10 The SERS sensor chip described in Embodiments 1, 6, 7, and 8 of this invention is suitable for concentrations of 10... -8 Raman spectroscopy of M in 4-MPBA solution;

[0057] Among them, 1-conical periodic array structure substrate, 2-metal layer, 3-hollowed-out dielectric layer, 4-metal nanoparticle layer. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0059] Example 1

[0060] This embodiment provides a method such as Figure 1 The cone-shaped periodic array structure SERS sensor chip shown includes a cone-shaped periodic array structure substrate 1, a metal layer 2, a hollow dielectric layer 3 and a metal nanoparticle layer 4 stacked sequentially.

[0061] The cone structure in the cone-shaped periodic array structure substrate 1 is a pyramid cone structure, the angle between the side surface and the bottom surface of the cone structure is 70°, and the length of the bottom side of the cone structure is 5000nm;

[0062] The metal layer 2 has a thickness of 100 nm, the hollowed-out dielectric layer 3 has a thickness of 1 nm, and the metal nanoparticles in the metal nanoparticle layer 4 have a diameter of 50 nm.

[0063] The cone-shaped periodic array structure substrate 1 includes a silicon dioxide substrate, the metal layer 2 includes silver, the hollow dielectric layer 3 includes silicon dioxide, and the metal nanoparticles in the metal nanoparticle layer 4 include silver.

[0064] A schematic diagram of the fabrication process of the cone-shaped periodic array structure SERS sensor chip is shown below. Figure 2 As shown, the enhancement mechanism principle of the conical periodic array structure SERS sensor chip is as follows: Figure 3 As shown;

[0065] The fabrication method of the conical periodic array structure SERS sensor chip includes the following steps:

[0066] (1) A 2000nm negative resist is spin-coated on a silicon dioxide substrate, and a cone-shaped periodic array structure silicon dioxide substrate is obtained by electron beam exposure, development, fixing and etching. The bottom edge of the cone structure is 5000nm long and the angle between the side surface and the bottom surface of the cone structure is 70°.

[0067] (2) In step (1), a silver metal film with a thickness of 100 nm is prepared on the upper surface of the substrate by electron beam evaporation.

[0068] (3) 1 nm of silicon dioxide was deposited on the surface of the silver-plated cone-shaped periodic array structure silicon dioxide substrate prepared in step (2) using atomic layer deposition technology to obtain an intermediate chip;

[0069] (4) A 10nm silver metal film is deposited on the surface of the intermediate chip prepared in step (3) by magnetron sputtering. Silver metal nanoparticles with a diameter of 50nm are then prepared by annealing. Using the metal nanoparticles as a mask, the hollow dielectric layer 3 prepared in step (3) is etched with BOE vapor to create a hollow space, resulting in a cone-shaped periodic array structure SERS sensor chip. The SEM image of the cone-shaped periodic array structure SERS sensor chip is shown below. Figure 4 As shown;

[0070] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 5 and Figure 10 As shown.

[0071] Example 2

[0072] This embodiment provides a cone-shaped periodic array structure SERS sensing chip, which includes a cone-shaped periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer stacked sequentially.

[0073] The cone structure in the cone-shaped periodic array structure substrate is a pyramid cone structure, the angle between the side surface and the bottom surface of the cone structure is 50°, and the length of the bottom side of the cone structure is 1000nm;

[0074] The thickness of the metal layer is 60 nm, the thickness of the hollowed-out dielectric layer is 3 nm, and the diameter of the metal nanoparticles in the metal nanoparticle layer is 30 nm.

[0075] The conical periodic array structure substrate includes a silicon substrate, the metal layer includes gold, the hollow dielectric layer includes aluminum oxide, and the metal nanoparticles in the metal nanoparticle layer include gold.

[0076] The fabrication method of the conical periodic array structure SERS sensor chip includes the following steps:

[0077] (1) A 1000nm negative resist is spin-coated on a silicon substrate, and a conical periodic array structure silicon substrate is obtained by optical exposure, development, fixing and etching. The bottom side of the conical structure is 1000nm long and the angle between the side and bottom of the conical structure is 50°.

[0078] (2) In step (1), a gold film with a thickness of 60 nm is deposited on the upper surface of the substrate by electron beam evaporation.

[0079] (3) 3 nm of aluminum oxide was deposited on the surface of the gold-plated cone-shaped periodic array structure silicon substrate prepared in step (2) using chemical vapor deposition technology;

[0080] (4) In step (3), a 5nm gold film is deposited on the surface of the intermediate chip by electron beam evaporation, and gold nanoparticles with a diameter of 30nm are prepared by annealing. Using the metal nanoparticles as a mask, the hollow dielectric layer prepared in step (3) is etched by BOE vapor to create a hollow space and obtain a cone-shaped periodic array structure SERS sensor chip.

[0081] The cone-shaped periodic array structure SERS sensor chip obtained in this embodiment is immersed in a concentration of 10... -7 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 6 As shown.

[0082] Example 3

[0083] This embodiment provides a cone-shaped periodic array structure SERS sensing chip, which includes a cone-shaped periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer stacked sequentially.

[0084] The cone structure in the cone-shaped periodic array structure substrate is a pyramid cone structure, the angle between the side surface and the bottom surface of the cone structure is 45°, and the length of the bottom side of the cone structure is 800nm;

[0085] The thickness of the metal layer is 80 nm, the thickness of the hollowed-out dielectric layer is 4 nm, and the diameter of the metal nanoparticles in the metal nanoparticle layer is 25 nm.

[0086] The conical periodic array structure substrate includes a silver substrate, the metal layer includes copper, the hollow dielectric layer includes titanium dioxide, and the metal nanoparticles in the metal nanoparticle layer include copper.

[0087] The fabrication method of the conical periodic array structure SERS sensor chip includes the following steps:

[0088] (1) A silver substrate with a cone-shaped periodic array structure was prepared by nanoimprinting technology. The bottom side of the cone structure is 800 nm long and the angle between the side and the bottom of the cone structure is 45°.

[0089] (2) In step (1), a copper film with a thickness of 80 nm is prepared on the upper surface of the substrate by electron beam evaporation.

[0090] (3) 4 nm of titanium dioxide was deposited on the surface of the copper-plated conical periodic array structure silver substrate prepared in step (2) by electron beam evaporation.

[0091] (4) In step (3), a 4nm copper film is deposited on the surface of the intermediate chip by electron beam evaporation, and copper nanoparticles with a diameter of 25nm are prepared by annealing. Using the metal nanoparticles as a mask, the hollow dielectric layer prepared in step (3) is etched by BOE vapor to create a hollow space and obtain a cone-shaped periodic array structure SERS sensor chip.

[0092] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 7 As shown.

[0093] Example 4

[0094] This embodiment provides a cone-shaped periodic array structure SERS sensing chip, which includes a cone-shaped periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer stacked sequentially.

[0095] The cone structure in the cone-shaped periodic array structure substrate is a pyramid cone structure, the angle between the side surface and the bottom surface of the cone structure is 30°, and the length of the bottom side of the cone structure is 600nm;

[0096] The thickness of the metal layer is 80 nm, the thickness of the hollowed-out dielectric layer is 5 nm, and the diameter of the metal nanoparticles in the metal nanoparticle layer is 80 nm.

[0097] The conical periodic array structure substrate includes a PDMS flexible substrate, the metal layer includes platinum, the hollow dielectric layer includes silicon nitride, and the metal nanoparticles in the metal nanoparticle layer include gold.

[0098] The fabrication method of the conical periodic array structure SERS sensor chip includes the following steps:

[0099] (1) A PDMS substrate with a conical periodic array structure was fabricated by nanoimprint technology. The bottom side of the conical structure is 600 nm long and the angle between the side and the bottom of the conical structure is 30°.

[0100] (2) In step (1), a platinum film with a thickness of 80 nm is prepared on the upper surface of the substrate by electron beam evaporation.

[0101] (3) 5 nm silicon nitride was deposited on the surface of the platinum-plated cone-shaped periodic array structure PDMS substrate prepared in step (2) using atomic layer deposition technology;

[0102] (4) In step (3), a 15nm gold film is deposited on the surface of the intermediate chip by magnetron sputtering. Gold nanoparticles with a diameter of 80nm are prepared by annealing. Using the metal nanoparticles as a mask, the hollow dielectric layer prepared in step (3) is etched by BOE vapor to create a hollow space and obtain a cone-shaped periodic array structure SERS sensor chip.

[0103] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 8 As shown.

[0104] Example 5

[0105] This embodiment provides a cone-shaped periodic array structure SERS sensing chip, which includes a cone-shaped periodic array structure substrate, a metal layer, a hollow dielectric layer and a metal nanoparticle layer stacked sequentially.

[0106] The cone structure in the cone-shaped periodic array structure substrate is a pyramid cone structure, the angle between the side surface and the bottom surface of the cone structure is 80°, and the bottom side length of the cone structure is 1500nm;

[0107] The thickness of the metal layer is 80 nm, the thickness of the hollowed-out dielectric layer is 5 nm, and the diameter of the metal nanoparticles in the metal nanoparticle layer is 20 nm.

[0108] The conical periodic array structure substrate includes a silicon dioxide substrate, the metal layer includes palladium, the hollow dielectric layer includes molybdenum disulfide, and the metal nanoparticles in the metal nanoparticle layer include copper.

[0109] The fabrication method of the conical periodic array structure SERS sensor chip includes the following steps:

[0110] (1) A 1000nm negative resist is spin-coated on a silicon substrate, and a cone-shaped periodic array structure silicon dioxide substrate is obtained by electron beam exposure, development, fixing and etching. The bottom side of the cone structure is 1500nm long and the angle between the side and bottom of the cone structure is 80°.

[0111] (2) In step (1), a palladium film with a thickness of 80 nm is prepared on the upper surface of the substrate by electron beam evaporation;

[0112] (3) 5 nm of molybdenum disulfide was deposited on the surface of the palladium-plated cone-shaped periodic array structure silicon substrate prepared in step (2) using atomic layer deposition technology;

[0113] (4) In step (3), a 3nm copper film is deposited on the surface of the intermediate chip by magnetron sputtering. Copper nanoparticles with a diameter of 20nm are prepared by annealing. Using the metal nanoparticles as a mask, the hollow dielectric layer prepared in step (3) is etched by BOE vapor to create a hollow space and obtain a cone-shaped periodic array structure SERS sensor chip.

[0114] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 9 As shown.

[0115] Example 6

[0116] This embodiment provides a cone-shaped periodic array structure SERS sensing chip, which is the same as that in Embodiment 1 except that the diameter of the metal nanoparticles in the metal nanoparticle layer is 30nm.

[0117] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 1;

[0118] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 10 As shown.

[0119] Example 7

[0120] This embodiment provides a cone-shaped periodic array structure SERS sensor chip. Except for the fact that the angle between the side and bottom of the cone structure is 50°, the cone-shaped periodic array structure SERS sensor chip is the same as that in Embodiment 1.

[0121] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 1;

[0122] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 10 As shown.

[0123] Example 8

[0124] This embodiment provides a cone-shaped periodic array structure SERS sensor chip, which is the same as that in Embodiment 1 except that the thickness of the hollow dielectric layer is 5nm.

[0125] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 1;

[0126] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 10 As shown.

[0127] Example 9

[0128] This embodiment provides a cone-shaped periodic array structure SERS sensor chip, which is the same as that in embodiment 4 except that the thickness of the hollow dielectric layer is 10nm.

[0129] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 4;

[0130] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After being immersed in the R6G molecule solution of M for 12 hours, the solution was removed, dried with a nitrogen gun, and then subjected to Raman testing.

[0131] Example 10

[0132] This embodiment provides a cone-shaped periodic array structure SERS sensor chip, which is the same as that in embodiment 4 except that the thickness of the hollow dielectric layer is 15nm.

[0133] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 4;

[0134] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 8 As shown.

[0135] Example 11

[0136] This embodiment provides a cone-shaped periodic array structure SERS sensor chip, which is the same as that in Embodiment 4 except that the thickness of the hollow dielectric layer is 0.2 nm.

[0137] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 4;

[0138] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After being immersed in the R6G molecule solution of M for 12 hours, the solution was removed, dried with a nitrogen gun, and then subjected to Raman testing.

[0139] Example 12

[0140] This embodiment provides a cone-shaped periodic array structure SERS sensor chip. Except for the fact that the angle between the side and bottom of the cone structure is 20°, the cone-shaped periodic array structure SERS sensor chip is the same as that in embodiment 5.

[0141] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 5;

[0142] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 9 As shown.

[0143] Example 13

[0144] This embodiment provides a cone-shaped periodic array structure SERS sensor chip. Except for the fact that the angle between the side and bottom of the cone structure is 85°, the cone-shaped periodic array structure SERS sensor chip is the same as that in embodiment 5.

[0145] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 5;

[0146] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10...-6 After being immersed in the R6G molecule solution of M for 12 hours, the solution was removed, dried with a nitrogen gun, and then subjected to Raman testing.

[0147] Example 14

[0148] This embodiment provides a cone-shaped periodic array structure SERS sensing chip. Except for the diameter of the metal nanoparticles in the metal nanoparticle layer being 10 nm, the cone-shaped periodic array structure SERS sensing chip is the same as that in Embodiment 1.

[0149] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 1;

[0150] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After being immersed in a 4-MPBA molecular solution of M for 12 hours, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy.

[0151] Example 15

[0152] This embodiment provides a cone-shaped periodic array structure SERS sensing chip. Except for the diameter of the metal nanoparticles in the metal nanoparticle layer being 180 nm, the cone-shaped periodic array structure SERS sensing chip is the same as that in Embodiment 1.

[0153] Except for the adaptive changes in the fabrication method of the conical periodic array structure SERS sensor chip, the rest are the same as in Example 1;

[0154] In this embodiment, the cone-shaped periodic array structure SERS sensor chip was immersed in a concentration of 10... -8 After being immersed in a 4-MPBA molecular solution of M for 12 hours, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy.

[0155] Comparative Example 1

[0156] This comparative example provides a SERS sensing chip, which is the same as that in Example 1 except that it does not contain a hollow dielectric layer and a metal nanoparticle layer.

[0157] The method for preparing the SERS sensor chip is the same as in Example 1 except for steps (3) and (4).

[0158] The SERS sensor chip is immersed in a concentration of 10 -8 After 12 hours in a solution of M-MPBA molecules, the sample was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The test results are shown in the figure below. Figure 5 As shown.

[0159] Comparative Example 2

[0160] This comparative example provides a SERS sensing chip, which is the same as that in Example 2 except that it does not contain a metal layer;

[0161] The method for preparing the SERS sensor chip is the same as in Example 2 except for step (2).

[0162] The SERS sensor chip described in this comparative example is immersed in a concentration of 10... -7 After 12 hours in a solution of M-MPBA molecules, the solution was removed, dried with a nitrogen gun, and then subjected to Raman spectroscopy. The results are as follows: Figure 6 As shown.

[0163] Comparative Example 3

[0164] This comparative example provides a SERS sensing chip, which is the same as that in Example 3 except that the dielectric layer does not have a cutout.

[0165] The method for preparing the SERS sensor chip is the same as in Example 3, except that after preparing the copper nanoparticles in step (4), the metal nanoparticles are not used as a mask and the hollowed-out space is created by the hollowed-out dielectric layer prepared in step (3) of BOE vapor etching.

[0166] The SERS sensor chip described in this comparative example is immersed in a concentration of 10... -6 After 12 hours in a solution of M's R6G molecules, the solution was removed, dried with a nitrogen gun, and then Raman spectroscopy was performed. The results are as follows: Figure 7 As shown.

[0167] The Raman test results of the SERS sensor chips described in the above embodiments and comparative examples are shown in Table 1:

[0168] Table 1

[0169]

[0170]

[0171] Table 1 shows the immersion in a concentration of 10... -8 After M was dissolved in 4-MPBA, the Raman shift of the main characteristic peak was 1081 cm⁻¹. -1 Soak in 10 -7 After M was dissolved in 4-MPBA, the Raman shift of the main characteristic peak was 1081 cm⁻¹. -1 Soak in 10 -6 After M was dissolved in R6G molecule solution, the Raman shift of the main characteristic peak was 1310 cm⁻¹. -1 .

[0172] As can be seen from Table 1:

[0173] (1) Based on Example 1 and Comparative Example 1, and in combination Figure 5 It can be seen that, compared with Comparative Example 1, Example 1 showed a stronger Raman signal for the detection of 4-MPBA, and the main characteristic peak of 4-MPBA was observed at 1081 cm⁻¹. -1 The signal strength in Example 1 was approximately 18 times that of Comparative Example 1, indicating that the SERS chip obtained in Example 1 has stronger enhancement performance and higher detection sensitivity; Example 2 and Comparative Example 2, combined with... Figure 6 It can be seen that, compared with Comparative Example 2, Example 2 showed a stronger Raman signal for the detection of 4-MPBA, and the main characteristic peak of 4-MPBA was observed at 1081 cm⁻¹. -1 The signal strength in Example 2 was approximately 10 times that of Comparative Example 2, indicating that the SERS chip obtained in Example 2 had stronger enhancement performance and higher detection sensitivity. Example 3 and Comparative Example 3, combined with... Figure 7 It can be seen that, compared with Comparative Example 3, Example 3 has a stronger Raman signal for R6G detection, and the main characteristic peak of R6G is observed at 1310 cm⁻¹. -1 The intensity of the signal in Example 3 was about 5 times that of Comparative Example 3, indicating that the SERS chip obtained in Example 3 has stronger enhancement performance and higher detection sensitivity.

[0174] (3) Based on Examples 1 and 6-8, and in combination Figure 10 It can be seen that Example 1 showed the strongest Raman signal compared to Examples 6-8, indicating that when the geometric parameters of the cone-shaped periodic array structure SERS sensor deviate from the optimal parameters (including the angle between the side and bottom surfaces of the cone structure, the thickness of the perforated dielectric layer, and the diameter of the metal nanoparticles), the SERS enhancement performance will weaken and the detection sensitivity will decrease. Examples 4 and 9-11 show that the thickness of the perforated dielectric layer affects the detection sensitivity. Furthermore, combined with… Figure 8 It can be seen that, compared with Example 10, Example 4 has a stronger Raman signal for R6G detection, and the main characteristic peak of R6G is observed at 1310 cm⁻¹. -1 The intensity of the signal in Example 4 was approximately twice that of Example 10, indicating that the SERS chip obtained in Example 4 has stronger enhancement performance and higher detection sensitivity.

[0175] (4) As can be seen from Examples 5 and 12-13, the angle between the side and bottom surfaces of the conical structure affects the detection sensitivity, and combined with... Figure 9 It can be seen that, compared with Example 12, Example 5 has a stronger Raman signal for R6G detection, and the main characteristic peak of R6G is observed at 1310 cm⁻¹. -1The intensity of the signal in Example 5 was 3 times that in Example 12, indicating that the SERS chip obtained in Example 5 has stronger enhancement performance and higher detection sensitivity. As can be seen from Examples 1 and 14-15, the diameter of the metal nanoparticles in the metal nanoparticle layer also affects the detection sensitivity.

[0176] In summary, this invention provides a cone-shaped periodic array structure SERS sensor chip, its fabrication method, and its applications. The SERS sensor chip has advantages such as high enhancement performance, high detection sensitivity, and uniform detection signal, and has wide applications in environmental monitoring, food safety, industrial production, and human health monitoring.

[0177] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A SERS sensor chip with a conical periodic array structure, characterized in that, The conical periodic array structure SERS sensor chip includes a conical periodic array structure substrate, a metal layer, a hollow dielectric layer, and a metal nanoparticle layer stacked sequentially.

2. The SERS sensor chip with a conical periodic array structure according to claim 1, characterized in that, In the cone-shaped periodic array structure substrate, the cone structure is a pyramid cone structure; Preferably, the angle between the side surface and the bottom surface of the conical structure is 30-85°, and more preferably 50-70°; Preferably, the base length of the conical structure is 300-10000 nm.

3. The SERS sensor chip with a conical periodic array structure according to claim 1 or 2, characterized in that, The thickness of the metal layer is 50nm-400nm; Preferably, the thickness of the perforated dielectric layer is 0.5-10 nm, and more preferably 1-5 nm; Preferably, the diameter of the metal nanoparticles in the metal nanoparticle layer is 10-180 nm, and more preferably 20-100 nm.

4. The SERS sensor chip with a conical periodic array structure according to any one of claims 1-3, characterized in that, The conical periodic array structure substrate includes any one or a combination of at least two of the following: silicon substrate, silicon oxide substrate, sapphire, PDMS flexible substrate, or silver substrate. Preferably, the metal layer comprises a plasmonic metal material; Preferably, the perforated dielectric layer comprises any one or a combination of at least two of silicon oxide, molybdenum disulfide, aluminum oxide, titanium oxide, or silicon carbide; Preferably, the metal nanoparticles in the metal nanoparticle layer comprise plasmonic metal materials; Preferably, the plasmonic metallic material includes any one or a combination of at least two of gold, silver, copper, platinum, or palladium.

5. A method for fabricating a SERS sensor chip with a conical periodic array structure as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: A metal layer, a hollow dielectric layer, and a metal nanoparticle layer are sequentially fabricated on the surface of a cone-shaped periodic array structure substrate to obtain the cone-shaped periodic array structure SERS sensing chip.

6. The preparation method according to claim 5, characterized in that, The method for preparing the conical periodic array structure substrate includes any one or a combination of at least two of the following steps (A), (B), (C), or (D): (A) Coating an etchant onto the substrate surface, and obtaining the cone-shaped periodic array structure substrate through exposure, development, fixing and etching; (B) The conical periodic array structure substrate is prepared on the substrate surface by using a film tool and a nanoimprint method; (C) A monolayer of microspheres is coated on the substrate surface. Using the monolayer of microspheres as a mask, a wet etching process is used to obtain the cone-shaped periodic array structure substrate. (D) A positive photoresist is coated on the substrate surface, and the cone-shaped periodic array structure substrate is obtained by exposure, development, fixing, evaporation of hard mask, stripping and etching. Preferably, the substrate described in steps (A), (B), (C), and (D) is cleaned before use; Preferably, the exposure in step (A) includes optical exposure or electron beam exposure; Preferably, the coating method described in steps (A), (C), and (D) includes spin coating.

7. The preparation method according to claim 5 or 6, characterized in that, The method for preparing the metal layer includes any one or a combination of at least two of electron beam evaporation, magnetron sputtering, or chemical vapor deposition.

8. The preparation method according to any one of claims 5-7, characterized in that, The method for preparing the hollowed-out dielectric layer includes any one or a combination of at least two of electron beam evaporation, physical vapor deposition, chemical vapor deposition, or atomic layer deposition.

9. The preparation method according to any one of claims 5-8, characterized in that, The method for preparing the metal nanoparticle layer includes any one or a combination of at least two of electron beam evaporation, magnetron sputtering, chemical vapor deposition, or atomic layer deposition.

10. An application of the SERS sensor chip with a conical periodic array structure as described in any one of claims 1-4, characterized in that, The applications include the application of highly sensitive detection of trace molecules.

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