Ordered and disordered structure integrated nanoflower SERS chip and preparation method thereof

Abstract

The invention discloses an ordered and disordered structure integrated nanoflower SERS (Surface Enhanced Raman Scattering) chip and a preparation method thereof, and relates to the field of surface enhanced Raman scattering chip detection. The chip comprises a substrate layer, an ordered periodic nanostructure array metal layer, a disordered nanosheet metal layer and a nanoflower structure metal layer, the nanoflower structure metal layer and the disordered nanosheet metal layer are attached to the surface of the ordered periodic nanostructure array metal layer; the ordered periodic nanostructure array metal layer is attached to the surface of the substrate layer. The nanostructures of the nanoflower structure metal layer units comprise nanosheets, nanowires, nanospheres and the like. The preparation method comprises the steps of nanoimprinting, oxygen plasma etching, magnetron sputtering, electrochemical deposition and the like. The detection repeatability is guaranteed through an ordered structure, the hot spot density and strength are improved through a disordered structure, the preparation process is stable and reliable, the chip with the uniform surface and high repeatability can be produced, and the chip has wide application prospects in the fields of biochemical sensing, food safety, environment monitoring and the like.

Description

Technical Field

[0001] The invention relates to the field of surface enhanced Raman scattering chip detection, and in particular to a nanoflower SERS chip integrating ordered and disordered structures and a preparation method thereof. Background Art

[0002] Surface-enhanced Raman spectroscopy (SERS) is a molecular fingerprint spectroscopy with the advantages of single-molecule sensitivity and label-free. It is widely used in chemical analysis, environmental monitoring, molecular diagnosis and disease screening. Molecular detection based on SERS is usually achieved through the local field enhancement caused by the localized surface plasmon resonance effect generated by the tiny gaps in the noble metal nanostructures. In the sub-10 nm gap hotspot enhancement area, the SERS chip enhancement factor can reach 10 10 As mentioned above, this characteristic can be used to detect substances at ultra-low concentrations.

[0003] The SERS chip with disordered structure has large surface roughness and dense hotspot distribution, high detection sensitivity, and is usually prepared by bottom-up method. It is widely used in SERS preparation due to its low cost and simple preparation advantages. The nanostructure units of the SERS chip with disordered structure are randomly arranged. The randomness of its hotspot distribution reduces the repeatability of the SERS substrate detection signal, which greatly limits the practical application of the SERS substrate. The nanostructure unit arrangement of the SERS chip with ordered structure follows a periodic distribution, and is usually prepared by top-down method. The hotspots generated by it maintain good uniformity and have good signal repeatability in SERS detection. However, for the preparation of SERS chips with ordered structure, large and expensive equipment is usually required, and due to strict preparation process restrictions, even with the most advanced nano-preparation technology, it is still very challenging to construct a highly sensitive sub-10 nm gap ordered periodic array SERS chip. Therefore, it is of great significance to develop a simple low-cost SERS chip to achieve high sensitivity and high repeatability of detection. The present invention aims to develop a SERS chip based on an ordered and disordered integrated nanoflower structure to achieve a high degree of unity of SERS detection repeatability and high sensitivity. Summary of the invention

[0004] The purpose of the present invention is to provide a nanoflower SERS chip integrating ordered and disordered structures and a preparation method thereof, so as to solve the problem that the detection repeatability and sensitivity of traditional SERS chips are mutually restricted, and to achieve a high degree of unity of repeatability and high sensitivity in SERS detection.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A nanoflower SERS chip with integrated ordered and disordered structures, including a substrate layer, an ordered periodic nanostructure array metal layer, a disordered nanosheet metal layer, and a nanoflower structure metal layer;

[0007] The nanoflower structure metal layer and the disordered nanosheet metal layer are attached to the surface of the ordered periodic nanostructure array metal layer;

[0008] The ordered periodic nanostructure array metal layer is attached to the surface of the base layer.

[0009] Optionally, the base layer may be a polycarbonate flexible film or a silicon wafer; preferably a polycarbonate flexible film.

[0010] Optionally, the ordered periodic nanostructure array is nanorods or nanospheres.

[0011] Optionally, the material of the metal layer of the ordered periodic structure array is a composite of one or more of gold, silver, platinum or copper.

[0012] Optionally, the nanoflower structure metal layer and the disordered nanosheet metal layer are made of the same material, which is a composite of one or more of gold or silver.

[0013] Optionally, the period p of the ordered periodic nanostructure array is 450-500 nm, the diameter d is in the range of 200-300 nm, and the height h is 50-150 nm. Preferably, the period p of the ordered periodic nanostructure array is 500 nm, the diameter d is 240 nm, and the height h is 150 nm.

[0014] Optionally, the unit nanostructure of the nanoflower structure metal layer may be a disordered nanosheet, nanowire or nanosphere structure.

[0015] A method for preparing a highly repeatable SERS chip based on a nanoflower structure comprises the following steps:

[0016] 1) Using nanoimprint technology to imprint a periodic nanostructure array pattern on a substrate;

[0017] 2) Etching the nanostructure array obtained in the first step using oxygen plasma etching technology;

[0018] 3) Using magnetron sputtering technology to deposit a metal layer on the substrate surface to obtain an ordered periodic nanostructure array metal layer;

[0019] 4) The metal ions in the electrolyte are reduced into metal nanostructures by electrochemical deposition technology and deposited on the surface of the metal layer of the ordered periodic nanostructure array to obtain a metal nanoflower structure SERS chip.

[0020] In step 4), the magnitude of the electrochemical deposition current can be adjusted according to the ordered periodic array metal substrate cathode, the electrolyte is a solution containing metal ions, and the electrodeposition time is 10 to 60 minutes.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention effectively enhances the detection repeatability of the SERS chip by utilizing the orderliness of the periodic nanostructure array. The ordered periodic nanostructure array in the chip promotes the uniform distribution of the position and intensity of the local electromagnetic field hotspots of the plasmons generated by light excitation, ensuring that the signal obtained in each SERS detection is highly consistent, reducing the deviation and uncertainty of the detection results.

[0023] 2. The hot spots of the nanoflower structure are evenly distributed at the edge of the internal nanosheets, and the gaps between the nanoflower structures are small, which can provide stronger hot spot intensity. At the same time, the disordered and staggered nanosheet structure itself has a high strong electric field strength, which improves the sensitivity of the chip to the detection of target substances and can accurately detect substances with extremely low concentrations.

[0024] 3. Innovatively integrate the ordered periodic nanostructure array with the disordered nanosheet and nanoflower structure to achieve the synergistic effect of the ordered structure ensuring detection repeatability and the disordered structure improving the density and intensity of hot spots. This solves the problem of the mutual restriction between the detection repeatability and sensitivity of traditional SERS chips and achieves a high degree of unity between the two.

[0025] 4. The preparation process of the present invention is stable and reliable. Nanoimprint technology can accurately transfer the pattern on the nickel template to the substrate surface; oxygen plasma etching technology can finely etch the nanostructure array, and finally a SERS detection chip with uniform surface and high repeatability can be prepared to ensure the stability and consistency of product quality.

[0026] 5. The present invention has broad application prospects in practical applications such as biochemical sensing, food safety and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of a highly repeatable SERS chip based on a nanoflower structure provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the cross-sectional structure of a high-repeatability SERS chip based on a nanoflower structure of the present invention;

[0029] Figure 3 The electric field schematic diagram of the SERS chip based on the periodic array, nanoflower structure and disordered staggered nanosheets of the present invention;

[0030] Figure 4The electric field (|E / E0|) size statistics diagram of the SERS chip based on the periodic array, nanoflower structure and disordered staggered nanosheets of the present invention;

[0031] Figure 5 A flowchart for manufacturing a highly repeatable SERS chip based on a nanoflower structure provided in an embodiment of the present invention;

[0032] Figure 6 Schematic diagram of a top view of a periodic gold nanorod array structure under a scanning electron microscope in an embodiment of the present invention;

[0033] Figure 7 A schematic diagram of a top view of a structure of a high-repeatability SERS chip based on a nanoflower structure according to an embodiment of the present invention is shown in FIG.

[0034] Figure 8 A schematic diagram of a top view of a structure of a disordered staggered nanosheet SERS chip according to an embodiment of the present invention is a scanning electron microscope view;

[0035] Fig. 9 This is a Raman intensity diagram of Rhodamine 6G detected by the nanoflower SERS chip obtained at different electrodeposition times of the present invention;

[0036] Fig.10 The RSD graph of the Raman intensity of 4-MBA detected by the nanoflower SERS chip obtained at different electrodeposition times of the present invention;

[0037] Fig.11 This is a Raman intensity diagram of the nanoflower structure SERS chip of the present invention that was electrodeposited for 60 min to detect different concentrations of 4-MBA;

[0038] Fig.12 This is a Raman intensity diagram of the nanoflower structure SERS chip of the present invention that was electrodeposited for 60 min to detect different concentrations of Rhodamine 6G. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The embodiment of the present invention provides a high repeatability SERS chip based on a nanoflower structure, which includes a substrate layer, an ordered periodic nanostructure array metal layer, a disordered nanosheet metal layer, and a nanoflower structure metal layer. The nanoflower structure metal layer and the disordered nanosheet metal layer are attached to the surface of the ordered periodic nanostructure array metal layer, and the ordered periodic nanostructure array metal layer is attached to the surface of the substrate layer. When performing SERS detection, the orderliness of the periodic nanostructure array enhances the detection repeatability of the SERS chip, effectively realizing the unity of high repeatability and high sensitivity of SERS sensing, and has broad application prospects in practical applications such as biochemical sensing, food safety and environmental monitoring.

[0041] Example 1

[0042] Figure 1 Schematic diagram of the structure of the high repeatability SERS chip based on the nanoflower structure in this embodiment, Figure 2 Schematic diagram of the cross-sectional structure of the high repeatability SERS chip based on the nanoflower structure in this embodiment, which includes a substrate layer 1, an ordered periodic nanostructure array metal layer 2, a disordered nanosheet metal layer 3, and a nanoflower structure metal layer 4 in sequence.

[0043] As an embodiment of the present invention, the substrate layer 1 of the high repeatability SERS chip based on the nanoflower structure is a polycarbonate flexible film or a silicon wafer. Since the polycarbonate film is flexible, it has better ductility and is more practical than a hard substrate, so it is preferably used as the substrate layer of the SERS chip. The ordered periodic nanostructure array is a nanocolumn or a nanosphere, and the ordered periodic nanocolumn array is used as a preferred embodiment of the present invention. The material of the metal layer of the ordered periodic structure array is one or more composites of gold, silver, platinum or copper. Gold has better stability than other types of metals and is used as a preferred embodiment in the present invention. The material of the nanoflower structure metal layer and the disordered nanosheet metal layer is the same, which is a composite of one or more gold or silver. Compared with gold, silver has a more outstanding plasmon effect, so it is used as a preferred embodiment in the present invention. In an embodiment of the present invention, the composite structure of the above-mentioned SESR chip is defined by the following parameters: the period of the ordered periodic nanostructure array is p, the diameter is d, and the height is h. In one embodiment of the present invention, the period p of the ordered periodic nanostructure array is 450-500 nm, the diameter d is in the range of 200-300 nm, and the height h is 50-150 nm. As a preferred embodiment of the present invention, the period p of the ordered periodic nanostructure array is 500 nm, the diameter d is in the range of 240 nm, and the height h is 150 nm. The unit nanostructure of the nanoflower structure metal layer can be a disordered nanosheet, nanowire, or nanosphere structure. Since nanosheets are easier to form flower-like structures, they are used as a preferred embodiment of the present invention.

[0044] See also Figure 3 and Figure 4 In the ordered periodic nanopillar array structure, the location and intensity distribution of the plasmon local electromagnetic field hotspots generated by light excitation are uniform, and the repeatability of the SERS detection signal is good, but its electric field intensity is low. In the disordered interlaced nanosheet structure, although the strong electric field intensity is greatly improved compared with the ordered structure, its plasmon local electromagnetic field hotspots are scattered and the structural uniformity is poor. The hotspots of the nanoflower structure are more evenly distributed at the edges of the internal nanosheets, and the gaps between the nanoflower structures are smaller, providing a stronger hotspot intensity.

[0045] Example 2

[0046] This embodiment provides a method for preparing a stable and reliable SERS chip with a high repeatability of a nanoflower structure. Figure 5 This is a process diagram for preparing a highly repeatable SERS chip with a nanoflower structure in another embodiment of the present invention, the process comprising:

[0047] 1) Under the action of pressure and temperature, the nano-pattern on the nickel template is transferred to the surface of the polymer substrate using nano-imprint technology to obtain a nano-structure array pattern;

[0048] In this embodiment, a nickel template with a nanohole array is selected, and its period must match the period of the target ordered periodic nanostructure array. In this embodiment, a nickel template with a period of 500 nm is used. The surface roughness and pattern accuracy of the template are crucial, directly affecting the structural quality of the final chip. Ensure that the surface roughness of the template is lower than a certain value (Ra<0.5 nm) and the pattern accuracy reaches the nanometer tolerance range.

[0049] Polycarbonate is used as the polymer substrate material and cut into discs of suitable size, preferably with a diameter of 2.5 inches. Before use, the substrate surface is cleaned with nitrogen gas for 5 minutes using an ion air gun to remove dust on the substrate surface, and then the protective film on the substrate surface is removed for later use.

[0050] Place the polycarbonate substrate with the surface protective film removed flat on the nickel template of the nanopore array, put them into the nanoimprinting equipment together, and then completely cover the template and substrate with a clean polyethylene terephthalate (PET) film, and close the protective cover of the nanoimprinting equipment. Set the nanoimprinting parameters and adjust the cooling method to air cooling first. The imprinting process is set into three stages. The first stage has a pressure of 1 bar, a temperature of 150°C, and an imprinting time of 60s; the second stage has a pressure of 40 bar, a temperature of 150°C, and an imprinting time of 120s; the third stage is cooling, and the imprinting ends when the temperature drops to 110°C. This imprinting process enables the template pattern to be accurately transferred to the substrate surface under the combined action of pressure and temperature to form a periodic nanostructure array pattern. During the imprinting process, ensure that the pressure and temperature are evenly distributed to prevent incomplete pattern transfer or deformation due to local pressure or temperature differences.

[0051] 2) The nanostructure array obtained in the first step was etched using oxygen plasma etching technology, and the etching time was 425 s;

[0052] In this embodiment, the main chamber of the oxygen plasma etching equipment is first evacuated to a low vacuum state, and then the sample delivery chamber is broken to atmospheric pressure, and the nano-imprinted substrate is placed in the reaction chamber of the etching equipment for etching. The etching pressure is set to 8 Pa, the oxygen plasma flux is 50 sccm, the plasma is generated by a radio frequency power supply, and the etching power is set to 40 W. The etching time is set to 425 s. During the etching process, the high-energy oxygen ions in the oxygen plasma react with the excess polymer material on the surface of the nanostructure array, converting it into volatile gas, thereby removing the excess material, making the shape of the nanostructure more regular and the size more precise.

[0053] 3) Using magnetron sputtering technology to deposit a metal layer on the substrate surface to obtain an ordered periodic nanostructure array metal layer;

[0054] In this embodiment, the vacuum chamber of the magnetron sputtering equipment is evacuated to a high vacuum state, and the vacuum degree needs to reach 6.0 × 10 -7 Pa or less. Argon is introduced as sputtering gas, and the argon flow rate is controlled at 15-20 sccm. Chromium and gold are used as targets, and the sputtering power is set to 100-150 W, and the sputtering time is 30-40 min. During the sputtering process, a 3 nm thick chromium layer is first sputtered on the substrate surface, and then the gold layer is sputtered. Argon ions are accelerated to bombard the gold target under the action of electric and magnetic fields, so that gold atoms are sputtered out and deposited on the etched substrate surface, forming an ordered periodic nanostructure array metal layer. By controlling the sputtering power and time, the thickness of the metal layer can be precisely controlled to make the gold layer thickness reach 150 nm.

[0055] 4) The metal ions in the electrolyte are reduced to metal nanostructures by electrochemical deposition technology and deposited on the surface of the metal layer of the ordered periodic nanostructure array to obtain a metal nanoflower structure SERS chip. The electrochemical deposition current is adjusted according to the cathode of the ordered periodic array metal substrate, the electrolyte is a solution with metal ions, and the electrodeposition time is 10 to 60 minutes.

[0056] In this embodiment, an electrolyte is first prepared, and an appropriate amount of silver nitrate and citric acid are weighed and dissolved in deionized water to prepare an electrolyte with a silver nitrate concentration of 0.024 mol / L and a citric acid concentration of 0.02 mol / L. After magnetic stirring for 10 minutes, it is stored at room temperature. The substrate with an ordered periodic nanostructure array metal layer is used as a cathode and placed in an electrochemical deposition tank filled with a silver nitrate electrolyte. A platinum electrode is selected as the anode, and the distance between the two poles is controlled at 2 to 3 cm. According to the characteristics of the ordered periodic array metal substrate cathode, the electrochemical deposition current is adjusted to 0.05 mA / cm², and the electrodeposition time is set to 60 minutes. Under the action of the electric field, silver ions move to the cathode and are reduced to metallic silver on the cathode surface, first forming a disordered nanosheet metal layer, and then gradually growing into a nanoflower structure metal layer, and finally obtaining a complete ordered and disordered structure integrated nanoflower.

[0057] In this embodiment, a nickel template with nano-hole array is used, and nickel templates with different shapes and periods can be selected according to pattern requirements. The material of the polymer substrate can be polycarbonate or polydimethylsiloxane.

[0058] As a preferred embodiment of the present invention, see the top view of the scanning electron microscope of the periodic gold nanorod array structure in the embodiment of the present invention. Figure 6 , a periodic nanocolumn array was obtained by imprinting a nickel template with a nanohole array. The shape, size and arrangement of the nanocolumns were uniform, and the arrangement showed a high degree of order. Figure 7 A structural scanning electron microscope top view of a high-repeatability SERS chip based on a nanoflower structure provided in an embodiment of the present invention, wherein the nanoflower structure prepared by the above method grows uniformly along the nanopillars, maintaining the long-range order of the array structure and having relative disorder in the short range; the long-range order is inherited from the periodic nanopillar array prepared in the early stage, so that the position and intensity distribution of the plasmon local electromagnetic field hotspots generated by light excitation are relatively uniform, and when performing SERS detection, the signal obtained each time can remain highly consistent, which is beneficial to increase the repeatability of the detection and reduce the deviation and uncertainty of the detection results; the relative disorder in the short range is derived from the characteristics of the nanoflower structure itself; the hotspots of the nanoflower structure are evenly distributed at the edges of the internal nanosheets, and the gaps between the nanoflower structures are small, and its unique microstructure improves the hotspot density and intensity, ensuring high sensitivity of detection. Figure 8A schematic diagram of a structural scanning electron microscope top view of a disordered interlaced nanosheet SERS chip obtained by excessive electrodeposition provided in an embodiment of the present invention. When the electrodeposition time is 80 min, excessive electrodeposition occurs, and the nanoflower structure breaks the long-range order and grows into a completely disordered interlaced nanosheet structure. At this time, the uniformity of the originally evenly distributed hot spots is destroyed, and in SERS detection, the detection signal repeatability is poor.

[0059] The method for manufacturing the nanoflower structure SERS detection chip proposed in this embodiment can stably and reliably produce SERS detection chips with uniform surface and high repeatability.

[0060] Example 3

[0061] The ordered and disordered structure integrated nanoflower SERS chip described in this embodiment uses a polycarbonate flexible film as the base layer, which has a thickness of 75 μm, good flexibility and processing performance, and can adapt to various complex detection scenarios.

[0062] The metal layer of the ordered periodic nanostructure array uses nanopillars as the ordered periodic nanostructure, with a period p of 500nm, a diameter d of 240nm, and a height h of 150nm. The metal layer is made of gold, and a 60nm thick metal layer is deposited on the surface of the substrate by magnetron sputtering technology to ensure good conductivity and stability.

[0063] Both the disordered nanosheet metal layer and the nanoflower structure metal layer use silver as the metal material. Through electrochemical deposition technology, a nanostructure is formed on the surface of the ordered periodic nanostructure array metal layer. Among them, the unit nanostructure of the nanoflower structure metal layer is a nanosheet, which grows under the conditions of a silver ion concentration of 0.2 mol / L, a current density of 1 mA / cm², and an electroplating time of 40 minutes during the electrodeposition process, forming a uniform and highly active nanoflower structure.

[0064] The chip can detect concentrations of 10 -7 When the Rhodamine 6G solution was tested at 400 M, a clear Raman characteristic peak was shown, and the relative standard deviation (RSD) of multiple tests was less than 8%, which fully demonstrated its high sensitivity and good detection repeatability.

[0065] Example 4

[0066] The ordered and disordered structure integrated nanoflower SERS chip described in this embodiment uses a silicon wafer as the base layer. The silicon wafer has good mechanical strength and chemical stability, and its surface is specially hydrophilic treated to enhance adhesion with subsequent metal layers.

[0067] Ordered periodic nanostructure array metal layer: Nanospheres are selected as ordered periodic nanostructures, with a period p of 480nm, a diameter d of 280nm, and a height h of 100nm. The metal layer is made of silver-copper alloy (the mass ratio of silver to copper is 3:1), prepared by magnetron sputtering technology, and the thickness of the alloy layer is 70nm. This alloy has both the good plasmon effect of silver and the cost advantage of copper, which reduces the chip preparation cost to a certain extent.

[0068] The materials of the disordered nanosheet metal layer and the nanoflower structure metal layer are both silver. The unit nanostructure of the nanoflower structure metal layer is a nanowire. During the electrochemical deposition process, the silver ion concentration in the electrolyte is 0.15 mol / L, the current density is 0.8 mA / cm², and the electrodeposition time is 50 minutes. The nanowire grows vertically on the surface of the nanosphere array, forming a unique three-dimensional structure.

[0069] At a concentration of 10 -8 When the 4-MBA solution of M was tested, the chip was able to accurately detect the presence of the target substance, and the difference in signal intensity detected at different positions was small, with RSD less than 9%, reflecting good detection performance.

[0070] Example 5

[0071] The ordered and disordered structure integrated nanoflower SERS chip described in this embodiment has a base layer made of a polycarbonate flexible film with a thickness of 100 μm, which can provide stable support for the entire chip structure while ensuring flexibility.

[0072] Ordered periodic nanostructure array metal layer: The nanopillars are ordered periodic nanostructures, with a period p of 450nm, a diameter d of 200nm, and a height h of 80nm. The metal layer is made of gold-platinum alloy (the mass ratio of gold to platinum is 4:1), deposited by magnetron sputtering technology, with a thickness of 55nm. The gold-platinum alloy combines the stability of gold and the catalytic performance of platinum, which helps to improve the overall performance of the chip.

[0073] The materials of the disordered nanosheet metal layer and the nanoflower structure metal layer are both gold. The unit nanostructure of the nanoflower structure metal layer is a nanosphere. During the electrochemical deposition process, the metal ion concentration in the electrolyte is controlled to be 0.25 mol / L, the current density is 1.2 mA / cm², and the electrodeposition time is 30 minutes. The nanospheres are evenly distributed on the surface of the nanocolumn, forming a unique flower-like structure.

[0074] In the detection of trace pollutants in environmental water samples, the chip showed high sensitivity to a variety of pollutants (such as phthalates), with a detection limit as low as 0.5nM, and good repeatability of multiple tests, with an RSD of less than 7%, showing its great application potential in the field of environmental monitoring.

[0075] Example 6

[0076] The method for preparing a highly repeatable SERS chip based on a nanoflower structure described in this embodiment comprises the following steps:

[0077] 1) Use a nickel template with nanohole arrays, whose period is 500nm, matching the nanostructure array to be prepared later. Select polycarbonate resin as the polymer substrate and cut it into a suitable size, such as a 3cm×3cm square. Transfer the nanopattern on the nickel template to the surface of the polycarbonate resin substrate at a pressure of 40 bar and a temperature of 150°C. Keep the imprinting time for 12 minutes to obtain a clear and regular periodic nanostructure array pattern.

[0078] 2) Place the substrate with the nanostructure array pattern into an oxygen plasma etching device. Set the etching power to 100 W and the etching time to 425 s to make the outline of the nanostructure clearer, remove excess polymer material, and ensure the accuracy of the nanostructure.

[0079] 3) Using gold as the target, in a high vacuum environment (vacuum degree reaches 6×10 -4 Pa), argon gas was introduced, and the argon gas flow rate was 18 sccm. The sputtering power was set to 120 W, the sputtering time was 35 min, and a metal layer of an ordered periodic nanostructure array with a thickness of 60 nm was deposited on the substrate surface.

[0080] 4) Prepare a silver nitrate electrolyte with a silver ion concentration of 0.2 mol / L. The substrate with an ordered periodic nanostructure array metal layer is used as the cathode, and the electrochemical deposition current is adjusted to 1 mA / cm² according to the cathode characteristics. The electrodeposition time is set to 40 minutes, and a uniform and highly active nanoflower structure metal layer is formed on the substrate surface, in which the unit nanostructure of the nanoflower structure is a nanosheet, and finally a nanoflower structure SERS chip with excellent performance is obtained. After testing, the chip has a detection concentration of 10 -6 When the Rhodamine 6G solution was 0.4 M, the Raman signal was clear and the relative standard deviation (RSD) of multiple tests was less than 8%.

[0081] Example 7

[0082] The method for preparing a highly repeatable SERS chip based on a nanoflower structure described in this embodiment comprises the following steps:

[0083] 1) A nickel template with a nanopore array with a period of 480 nm was selected. The polymer substrate was made of polydimethylsiloxane, which was made into a circular sheet with a diameter of 4 cm. The nanopattern on the nickel template was transferred to the polydimethylsiloxane-based substrate surface at a pressure of 40 bar and a temperature of 150°C. The imprinting time was 10 minutes, and a periodic nanosphere structure array pattern was obtained.

[0084] 2) Place the substrate into the etching equipment, set the etching power to 90 W, the etching time to 425 s, and perform fine etching on the nanosphere structure array to optimize the shape and size uniformity of the nanospheres.

[0085] 3) The target material is silver-copper alloy (mass ratio of silver to copper is 3:1), and the vacuum degree is 7×10 -4 In an environment of 1.5 Pa, argon gas was introduced at a flow rate of 16 sccm. The sputtering power was set to 130 W, the sputtering time was 40 min, and a metal layer of an ordered periodic nanostructure array with a thickness of 70 nm was deposited on the substrate surface.

[0086] 4) Prepare an electrolyte with a silver ion concentration of 0.15 mol / L. Adjust the electrochemical deposition current to 0.8 mA / cm² according to the cathode conditions. The electrodeposition time is 50 min, and a nanoflower structure metal layer with nanowires as unit nanostructures grows on the substrate surface. The chip detects concentrations of 10 -7 When the 4-MBA solution was 0.5 M, the target substance could be accurately detected, and the RSD of the signal intensity detected at different positions was less than 9%.

[0087] Example 8

[0088] The method for preparing a highly repeatable SERS chip based on a nanoflower structure described in this embodiment comprises the following steps:

[0089] 1) A nickel template with a nanohole array with a period of 450nm was used. The polymer substrate was a polycarbonate resin, which was cut into squares with a side length of 4cm. The nanopattern on the nickel template was transferred to the surface of the polycarbonate resin substrate at a pressure of 40bar and a temperature of 150℃. The imprinting time was 15min, and a periodic nanopillar structure array pattern was obtained.

[0090] 2) Place the substrate into an oxygen plasma etching device, set the etching power to 110 W, and the etching time to 425 s, and etch the nanocolumn structure to make the shape of the nanocolumns more regular.

[0091] 3) Using gold-platinum alloy (mass ratio of gold to platinum 4:1) as the target, the vacuum degree was 5×10 -4In an environment of 1.577 Pa, argon gas was introduced at a flow rate of 20 sccm. The sputtering power was 140 W, the sputtering time was 30 min, and an ordered periodic nanostructure array metal layer with a thickness of 55 nm was deposited on the substrate surface.

[0092] 4) Prepare an electrolyte with a metal ion concentration of 0.25 mol / L (containing the corresponding gold ions). Adjust the electrochemical deposition current to 1.2 mA / cm² according to the cathode characteristics. The electrodeposition time is 30 minutes, and a nanoflower structure metal layer with nanospheres as unit nanostructures is formed on the substrate surface. When the chip detects phthalates in environmental water samples, the detection limit is as low as 0.5 nM, and the RSD of multiple detections is less than 7%.

[0093] See also Fig. 9 The SERS chip with nanoflower structure and nanopillar array chip with different electrodeposition time detected the concentration of 10 -6 The sensitivity and repeatability of SESR signals of Rhodamine 6G with different structures were compared. The SERS chip with periodic gold nanopillar array structure obtained by nanoimprinting at 0 min has the weakest SERS signal intensity at the characteristic peak. At this time, the chip only has the basic periodic nanopillar array structure, and has not yet formed a nanoflower structure that can effectively enhance the signal. The SERS chips with different forms of nanoflower structures obtained after electrodeposition have an order of magnitude higher signal intensity at the characteristic peak than the SERS chips with the initial periodic gold nanopillar array structure, and the SERS chip with nanoflower structure obtained by electrodeposition for 60 min has the strongest detection signal.

[0094] Fig.10 The relative standard deviation (RSD) of the SERS intensity of 4-MBA detected by the SERS chips obtained by electrodeposition at different times is shown in Figure 2. RSD is a key indicator for measuring detection repeatability. The smaller the RSD value, the better the repeatability of the detection result. For the SERS chips with periodic gold nanorod array structure and nanoflower structure within 60 min of electrodeposition time, the intensity RSD is less than 10%, indicating good detection repeatability, and the nanoflower structure with 60 min of electrodeposition time has the highest detection sensitivity. When the over-deposition forms a completely disordered structure, the intensity RSD exceeds 10%, and the detection repeatability is poor.

[0095] Experiments show that the high-repeatability SERS chip based on the nanoflower structure has good detection performance and high repeatability compared with periodic nanostructure array chips and completely disordered nanostructure chips, and has great application potential in SERS quantitative detection.

[0096] See also Fig.11, the SERS intensity graphs of the nanoflower structure SERS chip obtained by electrodeposition for 60 min to detect different concentrations of 4-MBA were compared. For higher concentrations of 4-MBA solutions, the nanoflower SERS chip showed a strong enhancement ability. When the concentration of the 4-MBA solution is 1 μM, it can be seen from the figure that the Raman characteristic peak is very clear, indicating that the chip can effectively capture the characteristic signal of the 4-MBA molecule at this concentration, and the signal intensity is high, reflecting that the nanoflower structure has good responsiveness to the detection of high-concentration substances; even when the 4-MBA concentration is as low as 0.1 nM, the nanoflower chip can still detect the corresponding Raman characteristic peak; fully proving the excellent detection sensitivity of the chip of the present invention.

[0097] Reference Fig.12 , using the nanoflower structure SERS chip with 60min of electrodeposition to detect rhodamine 6G solutions of different concentrations, also achieved excellent results. The detection limit of the chip is as low as 0.1nM, indicating that in low-concentration rhodamine 6G solutions, the chip of the present invention can still accurately detect the presence of the target substance and produce clearly identifiable Raman characteristic peaks. This shows the versatility and efficiency of the chip of the present invention in detecting various substances.

[0098] Experiments show that the highly repeatable SERS chip based on the nanoflower structure of the present invention has a low detection limit, exhibits good detection performance, and has great application potential in actual SERS detection.

[0099] The above is a preferred embodiment of the present application. Obviously, those skilled in the art can make various modifications and changes to the embodiments of the present application without departing from the spirit and scope of the present application. In this way, if these modifications and changes are within the scope of the claims of the present application and their equivalents, the present application is also intended to cover these modifications and changes.

Claims

1. A nanoflower SERS chip integrating ordered and disordered structures, characterized in that: It includes a base layer, an ordered periodic nanostructure array metal layer, a disordered nanosheet metal layer, and a nanoflower structure metal layer; The nanoflower structure metal layer and the disordered nanosheet metal layer are attached to the surface of the ordered periodic nanostructure array metal layer; The ordered periodic nanostructure array metal layer is attached to the surface of the base layer.

2. The nanoflower SERS chip with integrated ordered and disordered structures as claimed in claim 1, characterized in that: The base layer is a polycarbonate flexible film or a silicon wafer.

3. The nanoflower SERS chip with integrated ordered and disordered structures as claimed in claim 1, characterized in that: The ordered periodic nanostructure arrays are nanorods or nanospheres.

4. The nanoflower SERS chip with integrated ordered and disordered structures as claimed in claim 1, characterized in that: The material of the ordered periodic structure array metal layer is a composite of one or more of gold, silver, platinum or copper.

5. The nanoflower SERS chip with integrated ordered and disordered structures as claimed in claim 1, characterized in that: The nano-flower structure metal layer and the disordered nano-sheet metal layer are made of the same material, which is a composite of one or more of gold or silver.

6. The ordered and disordered structure integrated nanoflower SERS chip as claimed in claim 1, characterized in that: The period p of the ordered periodic nanostructure array is 450-500 nm, the diameter d is in the range of 200-300 nm, and the height h is in the range of 50-150 nm.

7. The nanoflower SERS chip with integrated ordered and disordered structures as claimed in claim 1, characterized in that: The unit nanostructure of the nanoflower structure metal layer is a disordered nanosheet, nanowire or nanosphere structure.

8. A method for preparing a highly repeatable SERS chip based on a nanoflower structure, characterized in that: The steps include: 1) Using nanoimprint technology to imprint a periodic nanostructure array pattern on a substrate; 2) Etching the nanostructure array obtained in the first step using oxygen plasma etching technology; 3) Using magnetron sputtering technology to deposit a metal layer on the substrate surface to obtain an ordered periodic nanostructure array metal layer; 4) The metal ions in the electrolyte are reduced into metal nanostructures by electrochemical deposition technology and deposited on the surface of the metal layer of the ordered periodic nanostructure array to obtain a metal nanoflower structure SERS chip.

9. The method for preparing a highly repeatable SERS chip based on a nanoflower structure as claimed in claim 8, characterized in that: In step 1), the nanoimprint technique is used to imprint a periodic nanostructure array pattern on a substrate. Specifically, at a pressure of 40 bar and a temperature of 150°C, the nanopattern on the nickel template is transferred to the surface of a polymer substrate using the nanoimprint technique to obtain a nanostructure array pattern. The nickel template is a nanopore array nickel template, and the material of the polymer substrate is polycarbonate or polydimethylsiloxane.

10. The method for preparing a highly repeatable SERS chip based on a nanoflower structure as claimed in claim 8, characterized in that: In step 4), the magnitude of the electrochemical deposition current is adjusted according to the ordered periodic array metal substrate cathode, the electrolyte is a solution containing metal ions, and the electrodeposition time is 10 to 60 minutes.

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