Low-noise composite wetting surface-enhanced raman scattering substrate and preparation and application thereof

Abstract

The application provides a low-noise composite wettable surface enhanced Raman scattering substrate and a preparation method and application thereof. The preparation method comprises the following steps: treating a substrate by using a short pulse laser line scanning to obtain a substrate with a surface micro / nano structure; performing magnetron sputtering deposition on the substrate with the surface micro / nano structure to deposit a silver film, and then performing magnetron sputtering on the silver film by using a mask to deposit a hydrophilic titanium dioxide dielectric layer, thereby obtaining the low-noise composite wettable surface enhanced Raman scattering substrate. The low-noise composite wettable surface enhanced Raman scattering substrate is obtained by using the preparation method. The low-noise composite wettable surface enhanced Raman scattering substrate is applied to liquid sample Raman measurement. The application has the beneficial effect that the Raman scattering substrate is combined with surface wettability to prepare a Raman scattering substrate capable of being quickly dried and real-time detected.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of surface-enhanced Raman scattering, and particularly relates to a low-noise composite wetting surface-enhanced Raman scattering substrate, a preparation method of the low-noise composite wetting surface-enhanced Raman scattering substrate, and an application of the low-noise composite wetting surface-enhanced Raman scattering substrate. BACKGROUND

[0002] With the increasing demand for a better life, medical health has become a hot spot of social concern. Medical diagnosis technology is no longer limited to the characteristics presented by the surface of the disease, and needs to explore the source of the lesion and the pathogenesis and mechanism in order to diagnose and analyze it more accurately. Even the prevention of diseases can be carried out from the molecular level. The sudden epidemic has made us realize the necessity of developing molecular medicine. At the same time, in the face of a large number of and urgent sample detection needs such as national nucleic acid testing, it is of great significance to research and prepare detection tools that can realize rapid sample preparation, real-time and efficient detection of viruses and bacteria in biological medicine, and analysis of single-cell structural components.

[0003] Compared with traditional chemical analysis methods, Raman spectroscopy technology has the advantages of non-invasive and non-destructive, no need for complex pretreatment, rapid, small reagent consumption, small sample requirement, and high repeatability, and can realize rapid identification of the detected substance, and has great application prospects in clinical rapid diagnosis.

[0004] Whether in terms of detection technology or in terms of theoretical research, surface-enhanced Raman scattering is constantly developing, and is increasingly close to the needs of people's life and the needs of social development in practical application. Due to its high sensitivity, high repeatability, non-destructive detection and other unique molecular fingerprint recognition advantages, it has been widely used in the fields of molecular biology, clinical medicine and pathology.

[0005] At present, commonly used substrates include sol-based substrates, solid substrates and flexible substrates. Among them, the solid substrate has stable structure, good consistency and repeatability, but the cost is high and the preparation is complex. At present, many researchers are committed to improving the substrate by regulating different nanostructures, so as to continuously optimize the performance of SERS. As a SERS substrate, only when there are uniform and abundant metal micro / nano structures on the surface of the substrate material, can there be "hot spot" regions. In order to realize the enhancement of Raman signal, the surface topography and size of the substrate have a great influence on the Raman enhancement effect.

[0006] Currently, most researchers focus on improving the performance of the substrate to improve the sensitivity of SERS, but in the actual application process, when testing liquid samples, the droplet usually needs to be dried to make the molecules of the measured substance fully contact with the substrate hot spot, and the measured signal strength is improved. At room temperature, the droplet drying process usually takes more than half an hour, which reduces the test efficiency and makes it difficult to apply to real-time measurement. In addition, during the droplet drying process, the coffee ring effect (CRE) causes non-volatile compounds to gather at the edge of the substrate drying, which makes the repeatability of the sample signal worse. SUMMARY

[0007] The present application aims to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present application is to provide a preparation method of a low-noise composite wetting surface-enhanced Raman scattering substrate. For another example, another purpose of the present application is to provide a preparation method of a low-noise composite wetting surface-enhanced Raman scattering substrate. Still another purpose of the present application is to provide a low-noise composite wetting surface-enhanced Raman scattering substrate. Still another purpose of the present application is to provide an application of a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0008] In order to achieve the above-mentioned purposes, one aspect of the present application provides a preparation method of a low-noise composite wetting surface-enhanced Raman scattering substrate, the preparation method comprising the following steps: treating a substrate with a short pulse laser line to obtain a substrate with a surface micro / nano structure; magnetron sputtering deposition of a silver film on the substrate with a surface micro / nano structure, and then magnetron sputtering of a hydrophilic titanium dioxide dielectric layer on the substrate with a surface micro / nano structure by means of a mask to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0009] In an exemplary embodiment of the present application, the thickness of the magnetron sputtering deposited silver film can be 1-100 nm. For example, the thickness of the magnetron sputtering deposited silver film can be 2, 10, 20, 30, 50, 80, 90, 95 nm.

[0010] In an exemplary embodiment of the present application, the step can further comprise: pre-sputtering the substrate with a surface micro / nano structure, magnetron sputtering deposition of a silver film, and then magnetron sputtering of a hydrophilic titanium dioxide dielectric layer on the substrate with a surface micro / nano structure by means of a mask to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0011] Another aspect of the present application provides a method for preparing a low-noise composite wetting surface-enhanced Raman scattering substrate, the method comprising the following steps: magnetron sputtering deposition of a silver film on a substrate to obtain a silver film coated substrate; short pulse laser line scanning treatment of the silver film coated substrate to obtain a substrate with a silver film surface micro / nano structure; magnetron sputtering of a hydrophilic titanium dioxide dielectric layer on the substrate with a silver film surface micro / nano structure by means of a mask to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0012] In one exemplary embodiment of the present application, the thickness of the magnetron sputtering deposited silver film can be greater than 100 nm. For example, the thickness of the magnetron sputtering deposited silver film can be 120, 150, 200, 250 nm.

[0013] In one or more exemplary embodiments of the present application, the thickness of the magnetron sputtering deposited silver film can be greater than 100 nm. For example, the thickness of the magnetron sputtering deposited silver film can be 120, 150, 200, 250 nm.

[0014] In one or more exemplary embodiments of the present application, the low-noise composite wetting surface-enhanced Raman scattering substrate can obtain micro / nano structures, nano-scale surface structures can control the nano-size of silver to be in the order of hundreds of nanometers, and micro-scale surface structures can control hydrophilicity and hydrophobicity; wherein the hydrophilicity has a water contact angle of less than 50 degrees, and the hydrophobicity has a water contact angle of more than 100 degrees. For example, the hydrophilicity can be 0, 10, 30 degrees, and the hydrophobicity can be 110, 120, 150 degrees.

[0015] In one or more exemplary embodiments of the present application, the short pulse laser can use an infrared nanosecond pulse laser or an ultraviolet nanosecond pulse laser, the power of the infrared laser can be 1-50 W, and the power of the ultraviolet laser can be 0.1-20 W. For example, the power of the infrared laser can be 2, 3, 5, 10, 20, 30, 40, 49 W, and the power of the ultraviolet laser can be 0.5, 2, 3, 5, 10, 15, 19 W.

[0016] Another aspect of the present application provides a low-noise composite wetting surface-enhanced Raman scattering substrate obtained by the method for preparing a low-noise composite wetting surface-enhanced Raman scattering substrate described in any one of the above.

[0017] Still another aspect of the present application provides the use of a low-noise composite wetting surface-enhanced Raman scattering substrate as described above in the Raman spectroscopy measurement of a liquid sample.

[0018] Compared with the prior art, the present application can have at least one of the following beneficial effects:

[0019] 1) Laser processing with non-contact processing has more flexible, efficient, lower cost, more environmentally friendly characteristics.

[0020] 2) The combination of Raman scattering substrate and surface wettability can prepare a Raman scattering substrate that can be quickly dried and real-time detected. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1a The figure shows the water contact angle diagram of the substrate after processing with different laser powers under the scanning line spacing of 0.01-0.03 mm of Example 1 of the application;

[0022] Figure 1b The figure shows the water contact angle diagram of the substrate after processing with different laser powers under the scanning line spacing of 0.06-0.08 mm of Example 1 of the application;

[0023] Figure 2a The figure shows the water contact angle diagram of the substrate after coating titanium dioxide after scanning lines of 0.01-0.03 mm of Example 1 of the application;

[0024] Figure 2b The figure shows the water contact angle diagram of the substrate after coating titanium dioxide after scanning lines of 0.06-0.08 mm of Example 1 of the application;

[0025] Figure 3 The figure shows the X-ray energy spectrum diagram of the low-noise composite wettability surface-enhanced Raman scattering substrate after scanning lines of 0.07 mm of Example 1 of the application;

[0026] Figure 4 The figure shows the field emission scanning electron microscope diagram of the low-noise composite wettability surface-enhanced Raman scattering substrate under different magnifications after scanning lines of 0.07 mm of Example 1 of the application;

[0027] Figure 5a The figure shows the Raman spectrum diagram of the substrate surface prepared by treating with different laser powers under the scanning line spacing of 0.01 mm of Example 1 of the application; -6 MR6G;

[0028] Figure 5b The figure shows the Raman spectrum diagram of the substrate surface prepared by treating with different laser powers under the scanning line spacing of 0.03 mm of Example 1 of the application; -8 MR6G;

[0029] Figure 5c The figure shows the Raman spectrum diagram of the substrate surface prepared by treating with different laser powers under the scanning line spacing of 0.08 mm of Example 1 of the application; -8 MR6G;

[0030] Figure 5d Raman spectra of the substrate surface prepared by the embodiment 1 of the present application with a concentration of 10 -8 Raman spectra of the substrate surface prepared by the embodiment 1 of the present application with a concentration of 10

[0031] Figure 6 Raman spectra of the substrate surface prepared by the embodiment 1 of the present application with a concentration of 10 -9 Raman spectra of the substrate surface prepared by the embodiment 1 of the present application with a concentration of 10

[0032] Figure 7 Influence of laser power and silver sputtering power on the contact angle of the glass substrate surface of the embodiment 2 of the present application;

[0033] Figure 8 Variation of the contact angle with drying time of the embodiment 2 of the present application;

[0034] Figure 9a Raman spectra of the substrate surface prepared by the embodiment 2 of the present application with a concentration of 10 -8 Raman spectra of the substrate surface prepared by the embodiment 2 of the present application with a concentration of 10

[0035] Figure 9b Raman spectra of the substrate surface prepared by the embodiment 2 of the present application with a concentration of 10 -6 Raman spectra of the substrate surface prepared by the embodiment 2 of the present application with a concentration of 10

[0036] Figure 10a Field emission scanning electron micrograph of the SERS substrate of the embodiment 2 of the present application with a silver sputtering power of 20 W and a laser power of 10%.

[0037] Figure 10b Field emission scanning electron micrograph of the SERS substrate of the embodiment 2 of the present application with a silver sputtering power of 30 W and a laser power of 10%. DETAILED DESCRIPTION

[0038] Hereinafter, a low-noise composite wettability surface-enhanced Raman scattering substrate and its preparation and application will be described in detail in conjunction with the accompanying drawings and exemplary embodiments.

[0039] The present application can effectively improve the drying efficiency and repeatability by regulating the wettability of the substrate surface, and can appropriately improve the sampling detection efficiency and obtain better repeatability when the sensitivity of Raman measurement reaches the requirement.

[0040] First exemplary embodiment

[0041] In a first exemplary embodiment of the present application, a preparation method of a low-noise composite wetting surface enhanced Raman scattering (SERS) substrate is provided, and the preparation method comprises the following steps:

[0042] (1) Preparation of a SERS substrate

[0043] The substrate is processed by using a short pulse laser line to obtain a substrate with a surface micro / nano structure.

[0044] Specifically, the silicon substrate is processed by using an infrared laser or an ultraviolet laser to make the surface of the silicon substrate have sufficient roughness to provide a good substrate condition for subsequent silver particle deposition.

[0045] Optionally, the short pulse laser includes a femtosecond, picosecond, or nanosecond laser. The short pulse laser uses an infrared or ultraviolet nanosecond pulse laser.

[0046] Optionally, different morphologies of the substrate can be obtained by changing the laser power and the micro-pit gap (line spacing). That is, the line spacing of the laser and the power of the laser can control the attachment and aggregation of the subsequent silver nanoparticles on the silicon substrate. Here, the power of the infrared nanosecond pulse laser can be 1-50 W, the power of the ultraviolet nanosecond pulse laser can be 0.1-20 W, and the line spacing can be 0.001-1 mm. For example, the line spacing can be 0.1, 0.2, 0.5, 0.8, or 0.9 mm.

[0047] Different substrates have different optical parameters, and by selecting lasers with different wavelengths and pulse widths, the required surface micro / nano structure and roughness can be more effectively obtained. Generally, ultraviolet lasers can obtain smaller feature structures, and in addition, ultraviolet lasers can process a wider range of substrate materials, so short-wavelength lasers are preferred. In addition, the pulse width of the laser also affects the size of the micro / nano structure. Generally, the smaller the pulse width, the smaller the surface feature structure that can be obtained, and the wider range of substrate materials that can be processed. Therefore, short-wavelength short-pulse lasers are preferred for surface processing. By adjusting the laser power, scanning speed, and spacing, the morphology of the micro / nano structure can be effectively controlled, and the surface wettability can be controlled.

[0048] For example, when the laser is an ultraviolet nanosecond pulse laser, the laser parameters can be: spot diameter 0.01-0.05 mm, number of processes 1, processing speed 300-1500 mm / s, laser frequency 30-35 kHz, and laser 0.1-5 W. When the laser is an infrared nanosecond pulse laser, the laser parameters can be: spot diameter 0.01-0.05 mm, number of processes 1, processing speed 300-1500 mm / s, laser frequency 30-35 kHz, and laser 1-50 W.

[0049] In the example embodiment, the substrate can be selected from materials with weak Raman signals, such as glass, metal, etc. Metal is generally not Raman active. The substrate can be selected from silicon, which has a relatively strong Raman signal, but is relatively easy to control, has stable Raman peaks, and is relatively easy to eliminate, so a silicon wafer is used as the substrate.

[0050] (2) Depositing a silver film

[0051] The substrate with the surface micro / nano structure is subjected to magnetron sputtering to deposit the Ag film.

[0052] In the example embodiment, the magnetron sputtering can be direct current magnetron sputtering to deposit the silver film. The power of the magnetron sputtering can be 5-40 W, the time of the magnetron sputtering can be 180-220 s, the vacuum degree of the magnetron sputtering can be 2.7x10 -3 to 3.6x10 -3 Pa, and the gas pressure of the magnetron sputtering can be 0.1-0.3 Pa.

[0053] Optionally, sputtering can be achieved for materials used to make the target material, and the obtained film has high purity, good compactness, and can be prepared on a large-area substrate surface to have good uniformity and controllable thickness. The sputtering power and sputtering time can be changed to control the thickness of the prepared film. The argon flow rate, the vacuum degree of the vacuum chamber, and the gas pressure can affect the film quality, and even if the values are not reached, the film deposition fails. By controlling the power, sputtering time, and vacuum degree and gas pressure of the magnetron sputtering, the thickness, compactness, and morphology of the silver film can be effectively controlled, and the wettability and contact angle are changed.

[0054] In the example embodiment, the thickness of the silver film deposited by the magnetron sputtering can be 1-100 nm.

[0055] Optionally, the thickness of the silver film is greater than 100 nm, which can cause the micro / nano structure on the substrate surface to fail. The thickness of the silver film is less than 1 nm, which can cause the coating of the micro / nano structure on the substrate to be incomplete. The silver film that is too thick or too thin can reduce the intensity of the Raman signal. In addition, since the micro / nano structure directly affects the surface wettability and contact angle, the thickness of the silver film directly affects the wettability of the substrate.

[0056] In the example embodiment, step (2) can further include: pre-sputtering the substrate with the surface micro / nano structure, and then depositing the Ag film by magnetron sputtering.

[0057] Here, the pre-sputtering is used to clean the substrate surface to make the SERS substrate surface cleaner. The power of the pre-sputtering can be 20-40 W, the time of the pre-sputtering can be 110-130 s, and the vacuum degree of the pre-sputtering can be 2.7x10 -3 to 3.6x10-3 Pa, the pre-sputtering pressure can be 0.1-0.3 Pa.

[0058] (3) Depositing a hydrophilic titanium dioxide dielectric layer

[0059] A hydrophilic titanium dioxide dielectric layer is deposited by magnetron sputtering with a mask to obtain a low-noise composite wettable surface enhanced Raman scattering substrate.

[0060] Optionally, the mask is used to limit the area of the hydrophilic region. After the silver film is deposited, the surface becomes hydrophobic. When a liquid drop falls, it will land on the hydrophilic region, and the hydrophobic area will keep the liquid drop from falling outside. The hydrophilic region can be circular, but is not limited to a circular shape.

[0061] Optionally, the magnetron sputtering can be radio frequency magnetron sputtering to deposit a titanium dioxide film. The magnetron sputtering power can be 70-160 W, the magnetron sputtering time can be 120-600 s, and the magnetron sputtering vacuum degree can be 2.7 x 10 -3 -4.2 x 10 -3 Pa, the magnetron sputtering pressure can be 0.4-1.3 Pa.

[0062] Optionally, when direct current reactive magnetron sputtering is used to deposit a titanium dioxide film, a titanium target is used, and oxygen is introduced at the same time. The oxygen flow rate can be one-tenth of the argon flow rate. The magnetron sputtering power can be 70-160 W, and the magnetron sputtering time can be 120-600 s.

[0063] Optionally, by controlling the magnetron sputtering power, sputtering time, and vacuum degree and pressure, the thickness, density, and morphology of the titanium dioxide film can be effectively controlled, thereby changing the wettability and contact angle.

[0064] In the present exemplary embodiment, the thickness of the hydrophilic titanium dioxide dielectric layer deposited by magnetron sputtering can be no more than 10 nm.

[0065] The thickness of the titanium dioxide layer is preferably within 10 nm. If the titanium dioxide layer is too thick, the hot spots of the silver will fail. In theory, the thinner the titanium dioxide layer, the better the Raman enhancement. Therefore, in the case of changing the wettability, the thinner the titanium dioxide film layer, the better.

[0066] In the present exemplary embodiment, step (2) can further include: pre-sputtering with a mask, and depositing a hydrophilic titanium dioxide dielectric layer by magnetron sputtering to obtain a low-noise composite wettable surface enhanced Raman scattering substrate.

[0067] The pre-sputtering of step S2 cleans the target surface, making it relatively clean before deposition. The pre-sputtering power can be 80-160 W, the pre-sputtering time can be 110-130 s, and the pre-sputtering vacuum degree can be 2.7 x 10 -3to 4.2 x 10 -3 The pre-sputtering pressure can be 0.4-1.3 Pa.

[0068] In the present exemplary embodiment, the low-noise composite wetting surface-enhanced Raman scattering substrate can obtain micro / nano structures, the nanoscale surface structure can control the nanoscale size of silver to be in the order of hundreds of nanometers, and the micrometer scale surface structure can control the hydrophilicity and hydrophobicity; wherein the hydrophilicity is that the contact angle of water is less than 50 degrees, and the hydrophobicity is that the contact angle of water is greater than 100 degrees.

[0069] The above steps combine the surface wettability with the SERS substrate, and utilize short pulse laser and magnetron sputtering to prepare a hydrophobic / hydrophilic patterned surface SERS substrate.

[0070] Second exemplary embodiment

[0071] In the second exemplary embodiment of the present application, a preparation method of a low-noise composite wetting surface-enhanced Raman scattering substrate is provided, and the preparation method comprises the following steps:

[0072] (1) Depositing a silver film

[0073] After magnetron sputtering deposition of the silver film on the substrate, a substrate plated with a silver film is obtained.

[0074] Here, the silver film is deposited first, the deposited silver film is relatively thick, then laser treatment is performed, and then titanium dioxide is plated by using a mask, wherein the laser treatment is performed to avoid etching the silver film to expose the substrate, so that the background signal of the substrate can be reduced or removed, and the signal-to-noise ratio of the test can be improved.

[0075] In the present exemplary embodiment, the magnetron sputtering can be direct current magnetron sputtering to plate a silver film, the power of the magnetron sputtering can be 5-40 W, the time of the magnetron sputtering can be 180-220 s, and the vacuum degree of the magnetron sputtering can be 2.7 x 10 -3 to 3.6 x 10 -3 The pressure of the magnetron sputtering can be 0.1-0.3 Pa.

[0076] Optionally, by controlling the power, sputtering time, and vacuum degree pressure and other parameters of the magnetron sputtering, the thickness, density, and morphology of the silver film can be effectively controlled, and then the wettability and contact angle can be changed.

[0077] In the present exemplary embodiment, the thickness of the silver film deposited by the magnetron sputtering can be greater than 100 nm.

[0078] Optionally, the silver film greater than 100 nm is beneficial to reduce the background signal, and at the same time, prevents the silver film from being ablated by laser treatment.

[0079] In the example embodiment, the substrate can be selected from materials with weak Raman signals, such as glass, metal, etc. Metal is generally not Raman active. Silicon can also be selected as the substrate, although the Raman signal of silicon is relatively strong. However, the quality of silicon wafers is easy to control, the Raman peak is stable, and it is relatively easy to eliminate, so silicon wafers can also be used as the substrate.

[0080] In the example embodiment, step (1) can further include: performing pre-sputtering, and obtaining the substrate plated with the silver film after magnetron sputtering deposition of the silver film on the substrate.

[0081] The pre-sputtering is to clean the substrate to make the SERS substrate surface cleaner. The power of the pre-sputtering can be 20-40 W, the time of the pre-sputtering can be 110-130 s, the vacuum degree of the pre-sputtering can be 2.7x10 -3 Pa, the gas pressure of the pre-sputtering can be 0.1-0.3 Pa. -3

[0082] (2) Processing with nanosecond laser

[0083] The substrate plated with the silver film is processed with a short-pulse laser line to obtain a substrate with a micro / nano structure on the surface of the silver film.

[0084] When the silver film is processed with the laser, the laser parameters are selected to avoid complete etching of the silver film.

[0085] Optionally, the short-pulse laser includes femtosecond, picosecond, and nanosecond lasers. The short-pulse laser uses an infrared or ultraviolet nanosecond pulse laser.

[0086] Optionally, different substrates with different morphologies are obtained by changing the laser power and the micro-pit gap (line spacing). Here, the power of the infrared nanosecond pulse laser can be 1-50 W, the power of the ultraviolet nanosecond pulse laser can be 0.1-20 W, and the line spacing can be 0.01-0.1 mm.

[0087] For example, when the laser is an ultraviolet nanosecond pulse laser, the laser parameters can be: spot diameter 0.01-0.05 mm, number of processes 1, processing speed 300-1500 mm / s, laser frequency 30-35 kHz, and laser 0.1-5 W. When the laser is an infrared nanosecond pulse laser, the laser parameters can be: spot diameter 0.01-0.05 mm, number of processes 1, processing speed 300-1500 mm / s, laser frequency 30-35 kHz, and laser 1-50 W.

[0088] (3) Depositing a hydrophilic titanium dioxide dielectric layer

[0089] The substrate with the micro / nano structure on the surface of the silver film is plated with a hydrophilic titanium dioxide dielectric layer by magnetron sputtering with the aid of a mask to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.​

[0090] Optionally, the mask plate is used to limit the area of the hydrophilic region. After silver film is deposited, the surface becomes hydrophobic. When a liquid drop falls, it will land on the hydrophilic region, and the hydrophobic area will keep the liquid drop from falling outside. The hydrophilic region can be circular, but is not limited to a circular shape.

[0091] Optionally, the magnetron sputtering can be radio frequency magnetron sputtering to deposit a titanium dioxide film. The power of the magnetron sputtering can be 70-160 W, the time of the magnetron sputtering can be 120-600 s, the vacuum degree of the magnetron sputtering can be 2.7*10 -3 to 4.2*10 -3 Pa, and the gas pressure of the magnetron sputtering can be 0.4-1.3 Pa.

[0092] Optionally, when direct current magnetron sputtering is used to deposit a titanium dioxide film, a titanium target is used, and oxygen is introduced at the same time. The power of the magnetron sputtering can be 70-160 W, and the time of the magnetron sputtering can be 120-600 s.

[0093] Optionally, by controlling the power, sputtering time, vacuum degree, and gas pressure of the magnetron sputtering, the thickness, density, and morphology of the titanium dioxide film can be effectively controlled, and the wettability and contact angle can be changed.

[0094] In the example embodiment, the thickness of the hydrophilic titanium dioxide dielectric layer deposited by magnetron sputtering can be no more than 10 nm.

[0095] In the example embodiment, the thickness of the titanium dioxide layer is preferably within 10 nm. If the titanium dioxide layer is too thick, the hot spot of the silver will fail. In theory, the thinner the titanium dioxide layer is, the better the Raman enhancement will be. Therefore, in the case of changing the wettability, the thinner the titanium dioxide film is, the better.

[0096] In the example embodiment, step (3) can further include: pre-sputtering by means of a mask plate, magnetron sputtering to deposit a hydrophilic titanium dioxide dielectric layer, and obtaining a low-noise composite wettability surface-enhanced Raman scattering substrate.

[0097] In the example embodiment, the pre-sputtering is to clean the target surface so that the target surface is relatively clean before deposition. The power of the pre-sputtering can be 80-160 W, the time of the pre-sputtering can be 110-130 s, the vacuum degree of the pre-sputtering can be 2.7*10 -3 to 4.2*10 -3 Pa, and the gas pressure of the pre-sputtering can be 0.4-1.3 Pa.

[0098] In the present exemplary embodiment, the low-noise composite wetting surface-enhanced Raman scattering substrate can obtain micro / nano structures, the nanoscale surface structure can control the nanoscale size of silver to be in the order of hundreds of nanometers, and the microscale surface structure can control the hydrophilicity and hydrophobicity; wherein the hydrophilicity is that the contact angle of water can be less than 50 degrees, and the hydrophobicity is that the contact angle of water can be greater than 100 degrees.

[0099] The above steps combine the surface wettability with the SERS substrate, and utilize a short pulse laser and a magnetron sputtering to prepare a hydrophobic / hydrophilic patterned surface SERS substrate.

[0100] Third exemplary embodiment

[0101] In the third exemplary embodiment of the present application, a low-noise composite wetting surface-enhanced Raman scattering substrate is provided, which is obtained by the preparation method of the low-noise composite wetting surface-enhanced Raman scattering substrate according to any one of the above.

[0102] In the present exemplary embodiment, for example, the preparation method comprises the following steps: treating the substrate by nanosecond laser line scanning to obtain a substrate with surface micro / nano structures; magnetron sputtering deposition of a silver film on the substrate with surface micro / nano structures, and then magnetron sputtering plating of a hydrophilic titanium dioxide dielectric layer to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0103] In the present exemplary embodiment, for another example, the preparation method comprises the following steps: after magnetron sputtering deposition of a silver film on the substrate, a substrate plated with a silver film is obtained; the substrate plated with a silver film is treated by nanosecond laser line scanning to obtain a substrate with surface micro / nano structures of the silver film; the substrate with surface micro / nano structures of the silver film is magnetron sputtered to plate a hydrophilic titanium dioxide dielectric layer to obtain a low-noise composite wetting surface-enhanced Raman scattering substrate.

[0104] Fourth exemplary embodiment

[0105] In the fourth exemplary embodiment of the present application, the application of the low-noise composite wetting surface-enhanced Raman scattering substrate as described above in the measurement of liquid sample Raman spectrum, for example, in the application of dry liquid, is provided.

[0106] For example, the area where a 3mm hydrophilic titanium dioxide dielectric layer is plated by magnetron sputtering can limit 1 microliter of liquid to be just laid in the area, and when the surface is sufficiently hydrophilic, 1 microliter of liquid can be just laid in the area, which increases the liquid surface area, increases the solid-liquid contact area, and accelerates the drying speed.

[0107] In order to better understand the above-mentioned exemplary embodiments of the present application, a low-noise composite wetting surface enhanced Raman scattering substrate and its preparation and application are described below in connection with specific examples.

[0108] Example 1

[0109] (1) The silicon substrate is treated by using an infrared 1064 nm nanosecond pulse laser to make the surface have sufficient roughness, thereby providing a good substrate condition for subsequent deposition of silver particles. The laser parameters are: pulse width 10 ns, spot diameter 0.05 mm, processing number 1, processing speed 1500 mm / s, laser frequency 35 kHz, and maximum laser power 50 W. In the experiment, different morphologies of the substrate are obtained by changing the laser power and scanning line spacing. The specific laser parameters are shown in Table 1.

[0110] Table 1 Laser parameters

[0111]

[0112] In the above, the laser power of 55% corresponds to 27.5 W, the laser power of 65% corresponds to 32.5 W, the laser power of 75% corresponds to 37.5 W, the laser power of 80% corresponds to 40 W, the laser power of 85% corresponds to 42.5 W, and the laser power of 90% corresponds to 45 W.

[0113] (2) When using magnetron sputtering to prepare a thin film, in order to remove impurities on the surface of the target before the substrate starts sputtering, the target needs to be pre-sputtered. In this experiment, a silver film is deposited by direct current sputtering, and a TiO2 film is deposited by radio frequency sputtering. The specific magnetron sputtering parameters are shown in Table 2.

[0114] Table 2 Magnetron sputtering parameters

[0115]

[0116] The surface of the low-noise composite wetting surface enhanced Raman scattering substrate obtained in Example 1 will be analyzed below.

[0117] The surface wettability of the SERS substrate is detected by using a contact angle measuring instrument. It is found that the silicon wafer in the laser treatment area is a hydrophilic structure before silver plating, and the contact angle is between 4-50°. After the silver film is plated on the surface of the silicon wafer, the wettability of the substrate surface changes very obviously, and the contact angle increases obviously. The specific parameters are shown in Figure 1a and Figure 1b . Figure 1a Fig. 1 shows the water contact angle diagram of the substrate after treatment by each laser power under the scanning line spacing of 0.01-0.03 mm in Example 1 of the present application. Figure 1b Fig. 2 shows the water contact angle diagram of the substrate after treatment by each laser power under the scanning line spacing of 0.06-0.08 mm in Example 1 of the present application. From Figure 1aand Figure 1b It can be seen that when the silver film is plated on the silicon substrate, the substrate treated by laser with a scanning line interval of 0.01 mm, 0.02 mm or 0.03 mm becomes a hydrophobic structure, and the contact angle is between 93 and 138 degrees. When the substrate is treated by laser with a scanning line interval of 0.06 mm, 0.07 mm or 0.08 mm, the contact angle is about 140-150 degrees. The contact angle of the substrate first increases with the increase of laser power, and then decreases after reaching the maximum. And with the increase of laser power, the surface adhesion becomes lower.

[0118] In order to enable the SERS substrate to dry quickly, a hydrophilic titanium dioxide medium layer is plated on the basis, so that the surface wettability is changed. Different positions of the same sample are selected for multiple point detection, and the contact angle is averaged. The specific parameters are shown in Figure 2a and Figure 2b . Figure 2a The water contact angle diagram of the substrate plated with titanium dioxide after 0.01-0.03 mm scanning line of Example 1 of the application is shown; Figure 2b The water contact angle diagram of the substrate plated with titanium dioxide after 0.06-0.08 mm scanning line of Example 1 of the application is shown. As Figure 2a and Figure 2b can be seen, the TiO2 medium layer obviously changes the wettability of the surface of the SERS substrate, so that the detection area becomes a hydrophilic area, and the solid-liquid contact area increases after adding a droplet. It takes 13 minutes for a 1 microliter droplet to dry on the silicon wafer, while it takes 15 minutes for a 1 microliter droplet to dry on the silicon wafer plated with a silver film without a micro / nano structure. After plating the hydrophilic titanium dioxide film, the drying time is significantly reduced, and the minimum drying time is 5 minutes.

[0119] Through scanning electron microscopy for component analysis and surface morphology characterization, the X-ray energy spectrum and Figure 3 field emission scanning electron microscope (SEM) images under different magnifications can be obtained. As Figure 4 and Figure 3 and Figure 4 can be seen, through the EDS spectrum, it can be seen that the elements of the substrate are Si, Ag and a small amount of Ti and O. There is no other element to be doped, and the interference during Raman detection is less, which is conducive to improving the accuracy of the Raman signal in the detection process. The scanning electron microscope image can observe that the thin film deposited on the surface of the silicon wafer is dense. This is the Ag nanoparticles and TiO2 film deposited on the surface of the silicon wafer after laser treatment by magnetron sputtering. On the smooth surface of the untreated silicon wafer, the nanosilver particles deposited by magnetron sputtering are continuous and non-discrete. Therefore, in order to obtain nanoparticles with suitable nano gaps, the surface of the silicon wafer needs to be treated by laser to form a micro / nano structure, and then metal particles are deposited. The probe molecules can obtain strong Raman enhancement signal around these nanoparticles.

[0120] In order to improve the sensitivity of the SERS substrate, a 92nm silver film is plated on the surface of the silicon wafer which has been treated by short pulse laser in the previous stage by using physical vapor deposition film technology; in order to accelerate the drying time, a hydrophilic titanium dioxide medium layer with a diameter of 3mm is sputtered on the circular area by means of a mask plate, so as to increase the solid-liquid contact area. The present application mainly explores the influence of the laser scanning line spacing and the laser power on the SERS substrate. The results are shown in Figure 5a 、 5b , 5c, 5d and Figure 6 .

[0121] Figure 5a The concentration of the probe molecule R6G is 10 -6 M, the scanning line spacing is 0.01mm, and the laser power is different. Figure 5b 、 Figure 5c and Figure 5d are the Raman spectra of the substrate surface prepared by treating the substrate with 10 -8 M R6G at the laser power of 0.03mm, 0.08mm and 0.1mm respectively. Figure 6 is the influence of the laser power on the sensitivity of the SERS substrate.

[0122] According to Figure 5a 、 5b , 5c and 5d, when the scanning line spacing is 0.08mm, the sensitivity of the SERS is the best, and the probe molecule for Raman detection at this time is the R6G solution with a concentration of 10 -8 M. Under the same R6G concentration, when the scanning line spacing is 0.03mm and 0.08mm, the characteristic peaks of R6G at 611cm -1 and 1650cm -1 are more obvious than when the scanning line spacing is 0.1mm, and the effect is the best when the gap is 0.08mm. Figure 6 shows the Raman spectra of the substrate surface prepared by treating the substrate with 10 -9 M R6G at different laser powers. According to Figure 6 , when the probe molecule is changed to the R6G solution with a lower concentration of 10 -9 M, the characteristic peaks of R6G are very obvious when the laser power is 80%. Taking the R6G characteristic peak at 1650cm -1 as an example to calculate the enhancement factor, the enhancement factor of the SERS substrate treated at the laser power of 80% can reach 9.20×10 9 under the condition of the R6G solution with a concentration of 10 -9 M.

[0123] The embodiment 1 can improve the detection sensitivity of the SERS substrate and reduce the drying time.

[0124] Embodiment 2

[0125] In order to obtain a cleaner background peak, glass instead of silicon is selected as the substrate because the background peak of glass is relatively flat. At the same time, the order of laser surface treatment and silver film deposition is changed, and the silver film deposition parameters are optimized. After depositing a layer of silver film on the glass, the surface micro-nano structure is treated. Finally, a mask plate is prepared, and a TiO2 film is deposited in a partitioned manner. Finally, a patterned hydrophilic / hydrophobic combined Raman detection area is obtained.

[0126] (1) The thickness of the silver film is adjusted to obtain the optimal parameters, and the parameters are as shown in Table 3.

[0127] (2) The glass substrate plated with silver is treated by using a 355nm ultraviolet laser to make it have sufficient roughness. The basic parameters of the laser are as follows: processing number 1 time, processing speed 300mm / s, spot diameter 0.01mm, laser frequency 30kHz, and maximum laser power 5W. During the experiment, different morphologies of the substrate are obtained by changing the laser power and scanning line spacing. Since the laser processing is performed on the silver film surface, a pre-experiment is required. The laser power parameter varies from 5% to 85% for processing the substrate, and the final experiment selects the laser treatment power of 10%, 15% and 20%, respectively; the scanning line spacing is 0.01mm and 0.03mm, respectively.

[0128] Among them, 10% laser treatment power corresponds to 0.5W, 15% laser treatment power corresponds to 0.75W, and 20% laser treatment power corresponds to 1W.

[0129] (3) The specific parameters of magnetron sputtering silver film and titanium dioxide film are as shown in Table 3. In this round of experiment, the hydrophilic titanium dioxide medium layer is prepared by direct current sputtering of titanium target in oxygen.

[0130] Table 3 Magnetron sputtering parameters

[0131]

[0132]

[0133] The surface of the low-noise composite wetting surface-enhanced Raman scattering substrate obtained in embodiment 2 will be analyzed below.

[0134] The silver films with different thicknesses were sputtered on the glass sheets by controlling the sputtering power of a magnetron sputtering system, i.e., the sputtering power of group A was 20 W; the sputtering power of group B was 30 W; and the sputtering power of group C was 40 W. The glass substrate plated with silver was treated by a 355 nm ultraviolet laser with a scanning speed of 0.01 mm, and the maximum power of the laser was 5 W. Finally, a hydrophilic titanium dioxide layer was plated in a region to obtain the final SERS substrate, and the contact angle of the SERS substrate was shown as Figure 7 .

[0135] Figure 7 The effect of laser power on the contact angle of the glass substrate surface of example 2 of the present application was shown in the graph. Figure 7 As shown in the graph, under the conditions of three groups of silver films with different thicknesses, i.e., different sputtering powers of silver films, the contact angle changed with the increase of the laser power. When the sputtering power of the silver film was 20 W, the contact angle changed the most, and when the sputtering power of the silver film was 40 W, the contact angle only slightly decreased and was close to the contact angle of the glass. The contact angle of the glass was about 72.48°.

[0136] In order to test whether the substrate can achieve the purpose of rapid detection, 1 microliter of water droplets was dropped on the surface of the substrate treated under different conditions, and the drying time was observed. The shortest drying time was about 7 minutes. Figure 8 The change of the contact angle with time of example 2 of the present application was shown in the graph, Figure 9a The Raman spectrum of the 10 -8 M dopamine hydrochloride solution on the surface of the SERS substrate prepared by the silver films with different thicknesses and the sputtering power of 0 W (glass), 20 W and 40 W was shown in the graph; Figure 9b The Raman spectrum of the 10 -6 M dopamine hydrochloride solution on the surface of the substrate prepared by the silver film with the sputtering power of 30 W was shown in the graph. Figure 9a and 9b Under the conditions of three groups of silver films with different thicknesses, the region with the fastest drying was selected, and the contact angle was photographed to explore the change of the contact angle with time.

[0137] In this round of experiments, 10 -6 M and 10 -8 M dopamine hydrochloride solutions were used as probe molecules. The chemical formula of the dopamine hydrochloride solution was C8H 12 ClNO2, which was easily soluble in water. After 1 microliter of the dopamine hydrochloride solution was added to the surface of the SERS substrate, the detection was performed after no obvious liquid was observed on the surface. After data processing, the results were as follows Figure 9a and Figure 9bAs shown, A1 and A2 represent two points selected on the substrate of group A for detection, and the same applies to group C. The Raman shift of drugs like dopamine hydrochloride is mostly in the range of 3000–10000 cm⁻¹. -1 Within the range. When the dopamine solution is from 10... -8 M to 10 -6 As M changes, the Raman signal intensity also changes, with the enhancement factor at this point being 6.26 × 10⁻⁶. 6 .

[0138] Figure 10a The field emission scanning electron microscope (FESEM) of a SERS substrate with a silver film sputtering power of 20 W and a laser power of 10% according to Embodiment 2 of the present invention is shown. Figure 10b The field emission scanning electron microscope (SEM) image of a SERS substrate with a silver film sputtering power of 30 W and a laser power of 10% according to Embodiment 2 of the present invention is shown. The image is obtained through scanning electron microscopy. Figure 10a and 10b As shown, the silver film on the glass surface was partially ablated by laser treatment, resulting in a lower enhancement factor compared to the silicon substrate. Through parameter optimization, it is hoped that even lower background signal and a higher enhancement factor can be obtained.

[0139] Although the invention has been described above in conjunction with exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the exemplary embodiments of the invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate, characterized in that, The preparation method includes the following steps: A substrate with surface micro / nano structures was obtained by using short-pulse laser line scanning to process the substrate; A silver film was deposited by magnetron sputtering on a substrate with surface micro-nano structures, and then a hydrophilic titanium dioxide dielectric layer was deposited by magnetron sputtering with the help of a mask to obtain a low-noise composite wettability surface-enhanced Raman scattering substrate. The micro-nano structure obtained by the low-noise composite wettability surface-enhanced Raman scattering substrate has nanoscale surface structure controlling the nanoscale size of silver in the hundreds of nanometers, and microscale surface structure controlling hydrophilicity and hydrophobicity. The short-pulse laser is an infrared or ultraviolet nanosecond pulse laser, wherein the power of the infrared nanosecond pulse laser is 1 to 50 W, and the power of the ultraviolet nanosecond pulse laser is 0.1 to 20 W. The enhancement factor of the prepared substrate reached 9.2 × 10⁻⁶. 9 ; The prepared low-noise composite wettability surface-enhanced Raman scattering substrate was applied to Raman spectroscopy measurements of liquid samples, including the detection of R6G molecules and dopamine hydrochloride drugs.

2. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The thickness of the hydrophilic titanium dioxide dielectric layer deposited by magnetron sputtering is no more than 10 nm.

3. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The hydrophilicity is defined as a water contact angle of less than 50 degrees, and the hydrophobicity is defined as a water contact angle of greater than 100 degrees.

4. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 1, characterized in that, The steps also include: A substrate with surface micro-nano structures is pre-sputtered and then a silver film is deposited by magnetron sputtering. A hydrophilic titanium dioxide dielectric layer is then deposited by magnetron sputtering with the help of a mask to obtain a low-noise composite wettability surface-enhanced Raman scattering substrate.

5. A method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate, characterized in that, The preparation method includes the following steps: After magnetron sputtering to deposit a silver film on the substrate, a substrate coated with a silver film is obtained; The substrate coated with a silver film is processed by short-pulse laser line scanning to obtain a substrate with a surface micro-nano structure of silver film. A low-noise composite wettability surface-enhanced Raman scattering substrate is obtained by magnetron sputtering a hydrophilic titanium dioxide dielectric layer onto a substrate with a silver film surface micro / nano structure using a mask. The micro-nano structure obtained by the low-noise composite wettability surface-enhanced Raman scattering substrate has nanoscale surface structure controlling the nanoscale size of silver in the hundreds of nanometers, and microscale surface structure controlling hydrophilicity and hydrophobicity. The short-pulse laser is an infrared or ultraviolet nanosecond pulse laser, wherein the power of the infrared nanosecond pulse laser is 1 to 50 W, and the power of the ultraviolet nanosecond pulse laser is 0.1 to 20 W. The enhancement factor of the prepared substrate reached 9.2 × 10⁻⁶. 9 ; The prepared low-noise composite wettability surface-enhanced Raman scattering substrate is used in Raman spectroscopy measurements of liquid samples, including the detection of R6G molecules and dopamine hydrochloride drugs.

6. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 5, characterized in that, The thickness of the silver film deposited by magnetron sputtering is greater than 100 nm.

7. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 5, characterized in that, The thickness of the hydrophilic titanium dioxide dielectric layer deposited by magnetron sputtering is no more than 10 nm.

8. The method for preparing a low-noise composite wettability surface-enhanced Raman scattering substrate according to claim 5, characterized in that, The hydrophilicity is defined as a water contact angle of less than 50 degrees, and the hydrophobicity is defined as a water contact angle of greater than 100 degrees.

9. A low-noise composite wettability surface-enhanced Raman scattering substrate, characterized in that, The low-noise composite wettable surface-enhanced Raman scattering substrate is obtained by the preparation method of the low-noise composite wettable surface-enhanced Raman scattering substrate according to claim 1.

10. A low-noise composite wettability surface-enhanced Raman scattering substrate, characterized in that, The low-noise composite wettable surface-enhanced Raman scattering substrate is obtained by the preparation method of the low-noise composite wettable surface-enhanced Raman scattering substrate as described in claim 5.

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