Method for manufacturing matrix of plasmonic structures based on metal nanowires

Abstract

FIELD: additive technologies.SUBSTANCE: invention relates to a method for producing a matrix of plasmonic structures by microplotter printing using functional inks based on metal nanowires. It can be used for the development of photocells based on plasmonic structures, SERS signal amplification, signal amplification when recording a fluorescence spectrum, amplification of photocatalytic reactions, LED and OLED control, for plasmonic waveguides, in biomedicine and other fields. Functional ink based on metal nanowires in isopropyl alcohol is placed in a capillary dispenser of a microplotter and a matrix of plasmonic structures of the required geometry is formed using microplotter printing on a substrate that has been previously degreased and cleaned using acetone and isopropyl alcohol. The resulting matrix of structures is subjected to heat treatment at a temperature of 80-120 °C in an air atmosphere for 20-60 minutes to evaporate the residual solvent and wash using formic acid diluted with isopropyl alcohol. The resulting sample is subjected to heat treatment at a temperature of 100 °C in air atmosphere for 10-30 minutes.EFFECT: formation of a matrix of plasmonic structures with specified lateral dimensions and spatial positioning on a substrate without the need for masks, increasing the uniformity of the thickness of the resulting coatings and, as a result, reducing the coefficient of variation of their characteristics.2 cl, 5 ex

Description

[0001] The invention relates to a method for producing a matrix of plasmonic structures by microplotter printing using functional inks based on metal nanowires. The invention can be used to amplify the SERS signal, amplify the signal when recording a fluorescence spectrum, develop photocells based on plasmonic structures, plasmonic waveguides, control LEDs and OLEDs, enhance photocatalytic reactions, and in biomedicine and other fields.

[0002] A method for synthesizing metal nanowires on a copper plate for subsequent use as plasmonic structures for SERS studies is known. One of the methods is described in [1]. To form gold nanowires (AuNWs), a pre-cleaned copper plate is immersed in an aqueous solution of HAuCl4, then washed and dried. As a result, nanowires with a diameter of less than 10 nm are synthesized on the plate. The calculated plasmon enhancement coefficient of the samples for the analyte rhodamine 6G (R6G) was 4.9×10 3. In addition, a method for producing a plasmonic structure from silver nanoparticles based on a copper mesh plate is known [2]. For this, a mesh with a structure in the form of hexagonal holes of 400 mesh is cleaned in ethanol and deionized water, treated with hydrochloric acid for 3 minutes and fixed on a quartz substrate, after which a solution of silver nitrate in ethanol with a concentration of 0.4 mmol / L is applied for 10 minutes. The sample is washed with ethanol and deionized water and dried in a vacuum chamber at a temperature of 400 C for 5 minutes. The obtained SERS signal enhancement factor in the study of transformer oil with a furfural concentration of 88 mg / L was 10 3 - 10 4 mol / l. A similar method for creating a plasmonic-active surface is described in a patent [3]. A copper plate measuring 2x2 cm 2The sample is cleaned with ethanol and deionized (DI) water, then immersed in a 1% hydrochloric acid solution for 2-3 minutes. After this, the sample is immersed in a mixture of tin chloride (SnCl2), silver nitrate (AgNO3), and ethylenediaminetetraacetic acid (EDTA) solutions for 10-12 minutes, resulting in the formation of a layer of silver nanoparticles (AgNPs) on the wafer surface. Next, the sample is rinsed with DI water and ultrasonicated (US) in ethanol for 30 seconds. To improve the plasmonic properties, a graphene oxide-based dispersion is spin-coated onto the surface. SERS studies of the substrates were performed using R6G and mercaptobenzoic acid (MBA) as analytes. The coating homogeneity and reproducibility of the signal enhancement, as well as improved plasmonic properties and increased stability, were demonstrated with the graphene oxide layer.The disadvantages of the considered method include the high consumption of materials for the formation of nanowires, the impossibility of obtaining structures of complex geometry without the use of lithography, as well as the limited applicability of samples in transparent devices due to the use of a metal plate as a substrate for synthesis.

[0003] In addition, methods for creating non-planar structures for SERS based on metal nanowires have been described in the literature. For example, a method for using single ultra-long silver nanowires (AgNWs) as plasmonically active objects for molecular imaging in two-dimensional and three-dimensional cellular models is known [4]. AgNWs are synthesized electrochemically: a carbon nanoelectrode with a potentiostat is immersed in a mixture of silver nitrate (AgNO3) and sodium citrate (Na3C6H5O7) solutions. Nanowires up to 150-200 μm long and approximately 300 nm in diameter are formed at the tip of the electrode. The rough surface of the resulting wires acts as an amplifier of the SERS signal, facilitating the formation of "hot spots." To study the SERS characteristics, nanowires are placed inside cells using a 4D microcontroller, after which spectra are recorded along the nanowire in different areas of the cell using a confocal microscope. The resulting SERS signal enhancement factor is 2.53×105 .

[0004] The preparation of plasmonic structures based on bimetallic gold and silver nanowires embedded in polymer fibers has also been described [5]. To obtain nanowires, 10 μl of a 0.25 mol / l hydrogen tetrachloroaurate (III) (HAuCl4) solution in water are mixed with 10 ml of diethylene glycol (DEG) and stirred for 2 minutes to form gold nanoparticles. Afterwards, a mixture of 0.004 mg silver nitrate (AgNO3) in 10 μl of deionized water and 2 ml of DEG is added to the reactor and the mixture is kept in an oil bath at 210°C for 30 minutes. As a result, silver nanowires grow on the gold nanoparticles, which, when connected, form a structure consisting of a large number of segments: gold nanoparticles and silver nanowires. For purification, the composition is dissolved in water and centrifuged at 11,000 rpm, after which a colloidal solution of nanowires in water is obtained.The nanowires are then dispersed in a copolymer solution and formed into nanofibers using electrohydrodynamic inkjet printing. In the next step, the fibers are heated to 175°C to form chemical bonds between the polymer chains, increasing structural stability. Plasmonic properties are studied using malachite green isothiocyanate (MGITC), with a detection limit of 10. -6 mol / l.

[0005] The work [6] describes a method for creating silver nanowires with a high aspect ratio and the use of their dispersion to enhance the SERS signal. The synthesis of AgNWs (average length 6.5 μm, average diameter 17 nm) is carried out by a modified seeding method at room temperature in an aqueous medium using cetyltrimethylammonium bromide as a stabilizer and structure-forming agent, as well as ascorbic acid as a reducing agent. Purification of the synthesized mixture is carried out by static precipitation, which allows obtaining stable (with a stability of at least 3 months) samples. SERS activity of the nanowire dispersion was studied using dyes: crystal violet (CV), malachite green (MG) and Nile blue (NBC). The maximum enhancement factor of the sample was 3.5×10 5 .

[0006] In addition, a method for producing spherical particles based on silver nanowires and gold nanoparticles for SERS is known, described in the patent [7]. To produce plasmonic structures, a mixture of silver nanowires (diameter 20-60 nm, length 15-40 μm) and gold nanoparticles (size 10-70 nm) is prepared in water with a nanowire concentration of 12-45 mg / ml and a mass ratio of nanowires to nanoparticles from 3:1 to 10:1. The resulting dispersion is added dropwise (volume 3-15 μl) into liquid nitrogen for freezing and subsequent sublimation drying (1-100 Pa for 10-30 h). As a result, spherical structures with a diameter of 1.5-6 mm, consisting of silver nanowires and metal nanoparticles, are formed. When the analyzed solution (2-12 µl) is applied to the sphere, its molecules are deposited in the nanogaps between the nanowires and nanoparticles, which leads to signal amplification.To study the plasmonic characteristics of the invention, a solution of phenanthrene in ethanol was used; the sensitivity limit of the measurements was 10. -9 mol / l.

[0007] A method for creating a plasmonic structure based on silver nanowires and gold nanorods for detecting benzopyrene is also proposed [8]. A depression with specified dimensions is created on a polyethylene terephthalate (PET) substrate: the bottom area is 1-17 mm², the height is 3-9 mm. The synthesis of metal structures is carried out by a hydrothermal method. The result is silver nanowires with a diameter of 28-35 nm and a length of 30-38 μm and gold nanorods with a diameter of 10-15 nm and a length of 35-45 nm. Then, dispersions of nanowires and nanorods are mixed in various ratios. The resulting mixture fills the depression in the substrate, while the ratio of the volumes of the solution and the depression is 0.45-0.85. Finally, the substrate with the solution is frozen in liquid nitrogen and freeze-dried at a pressure of 1-50 Pa for 6-30 hours. This results in the formation of a porous three-dimensional structure of AgNWs and gold nanorods.The analyte molecules are trapped in the gaps between the nanostructures, enhancing their Raman signal. The sample's sensitivity limit for the analyte, determined using SERS detection, was 10. -9 mol / l. The key drawback of the above-described methods, which hinders their practical application, is the high technological complexity of forming plasmonic structures, as well as the emergence of additional difficulties when using such structures as sensors, due to their structural features.

[0008] In addition, inventions are described in which two types of nanostructures are combined to enhance plasmon resonance on a substrate. For example, in [9], the creation of a plasmonic structure based on silver nanowires and gold nanoparticles by a method of their sequential deposition from solutions is described. A colloidal solution of silver nanowires (length 15-25 μm, diameter 20-40 nm, concentration 0.5-1.5 mg / ml) is applied to a pre-cleaned glass substrate; the dispersion volume is 20-80 μl per 1 cm². The sample is dried at a temperature of 40-70°C until the solvent completely evaporates, thus forming a conductive network. Then, a colloidal solution of gold nanoparticles (concentration 0.5-1.2 mg / ml, volume 30-40 μl / cm² per drop) is deposited onto the resulting layer using the method of multiple (1-10 times) drop application and dried at 30-80°C.As a result, “hot spots” are formed between the silver nanowires and gold nanoparticles, which ensures the SERS sensitivity limit for RG6 studies is equal to the analyte concentration of 10. -7 mol / l.

[0009] Furthermore, a method for producing a SERS substrate for detecting a lung cancer biomarker based on gold and silver nanowires is known

[10] . To synthesize negatively charged silver nanowires, solutions of silver nitrate at a concentration of 0.1 mol / L and PVP at a concentration of 0.2 mol / L are added to ethylene glycol (EG), and the mixture temperature is maintained at 160°C. Positively charged gold nanoparticles (AuNPs) are obtained by mixing solutions of sodium borohydride (NaBH4, concentration of 0.15 mmol / L) and perchloric acid (HAuCl4, 24.3 mmol / L) for 40 minutes. Dispersions of sintered AgNWs and AuNPs are mixed in a volume ratio of 20:1, which leads to the electrostatic formation of Au-Ag nanowires. A solution of nanowires is then deposited onto a pre-treated silicon wafer, dried, and washed. p-Nitrobenzoic acid (NBA) is used to analyze plasmonic enhancement; the sensitivity of the method is 10 -12 mol / l.

[0010] Among other things, a method for producing a silver nanocomposite material with plasmonic properties is described in the patent

[11] . To form the structures, 0.05-0.08 g of AgNW are dispersed in 10-20 ml of water using a magnetic stirrer. After which an aqueous glucose solution is added to the mixture and hydrothermal synthesis is carried out at a temperature of 170-190°C for 3-5 hours. After cooling, the resulting composite is separated by centrifugation and dispersed in a solution of silver ammonia ([Ag(NH3)2]⁺). Then, a dispersion of PVP in ethanol and a mixture containing silver nitrate, citric acid (C6H8O7), and an aqueous solution of ascorbic acid (C6H8O6, concentration 0.1 g / ml) are added to the system. After 5-20 minutes, a shell of silver nanoparticles forms on the surface of the composite, thereby forming the final synthesis product in the form of a composite film. The resulting composite wires are purified by washing and centrifugation. Plasmon enhancement studies on R6G showed an analyte detection limit of 10 -12mol / L. The described samples exhibit high plasmonic enhancement, but the methods used to form the structures do not allow for the creation of complex geometries without the use of a mask and are characterized by excessive material consumption. Furthermore, using two components as the basis for the structure complicates the manufacturing processes, as well as the time and cost of sensor production. Finally, the interaction between the two materials can lead to reduced sensor stability.

[0011] In addition, methods for creating planar structures based solely on metal nanowires to enhance the Raman signal have been proposed in the literature. For example, a method for producing a flexible and stretchable SERS substrate based on silver nanowires is described in a patent

[12] . To synthesize nanowires, PVP is dissolved in ethylene glycol at 60°C for 1 hour, then a solution of iron (III) chloride (FeCl3) in ethylene glycol with a concentration of 1 mg / ml is added, the mixture is thoroughly mixed, and silver nitrate is added. The resulting mixture is transferred to an autoclave, where it is heated to 130°C for 6 hours. The product is then centrifuged (6000 rpm, 10 min) and washed with acetone and ethanol. As a result, silver nanowires with a diameter of 75-125 nm are obtained and dispersed in ethanol. The dispersion (10-20 ml) is applied by spincoating (300 rpm, 20 sec) onto the adhesive layer of a flexible stretch tape (original size 0.5×1.5 cm²).The resulting substrate is secured between two optical holders and an external force is applied, stretching it to 105%-150% of its original length. This stretching alters the nanogaps between the silver nanowires, increasing the concentration of "hot spots." It has been shown that the gain reaches its maximum value at a 10% stretch.

[0012]

[13] describes a method for forming a plasmonic-active surface based on AuNWs with the addition of carboxylic acids for the capture and analysis of protein molecules. A guiding pattern of nanostructures with a diameter of 15 nm and a pitch of 20 nm is created on a silicon wafer using lithography. A polymethyl methacrylate (PMMA) solution is then applied to the wafer, forming a polymer template. A gold layer is then deposited on this template using electron beam evaporation, producing a single-layer array of nanowires and transferring it to a silicon substrate. Repeating the process multiple times results in the formation of a multilayer nanostructure of nanowires. Subsequent etching of the structure in oxygen plasma converts the polymer residues on the surface of the wires into carboxylic acids. This allows the capture of target protein molecules for analysis. During SERS measurements, markers of Alzheimer's disease are used: beta-amyloid and tau protein as analytes, the signal enhancement factor is 5.5×10 5 .

[0013] In addition, a method for detecting the marine toxin GYM using a plasmonic coating based on a cross-linked AgNW network was developed

[14] . Nanowires are synthesized using the polyol method, and the final dispersion concentration is 5 mg / mL. To obtain the structure, 1-5 layers are formed on a silicon substrate using spin coating. This creates a cross-linked network structure of nanowires containing numerous "hot spots" on the substrate surface. R6G and the marine toxin Gymnodimine (GYM) are used to study the substrate. The method has demonstrated sensitivity for analyte concentrations of up to 10 -10It has been shown that excessive nanowire density leads to laser radiation shielding, while three layers provide the optimal thickness. The proposed methods provide efficient nanowire synthesis but do not allow the formation of plasmonic structures with complex geometries without the use of a mask. Furthermore, the spincoating method does not guarantee the uniformity and reproducibility of the resulting layer. The method for producing nanowires described in

[13] is characterized by high technological complexity and the impossibility of scaling up production. Finally, all these methods are characterized by high material consumption, in contrast to printed electronics approaches, where this indicator is minimal.

[0014] The method described in

[15] was used as a prototype for the invention. To create a plasmonic structure, the authors use a paper base with modified properties as a substrate. For this, filter paper is treated with a 3% chitosan solution, which fills the micropores of the cellulose, creating a smoother and more uniform surface. The sample is then immersed in a 0.2% solution of octadecyltrichlorosilane (C 18 H 37Cl3Si) and methyltrichlorosilane (CH3Cl3Si) in n-hexane, which imparts hydrophobic properties. Silver nanoparticles are synthesized by reducing silver nitrate. A solution of AgNO3 (0.0036 g silver nitrate in 198 ml deionized water) is heated in an oil bath, and 2 ml of a 1% aqueous sodium citrate solution (Na3C6H5O7) is added. The resulting dispersion is centrifuged at 6000 rpm for 10 minutes, after which the precipitate is mixed with glycerol and ethanol to improve rheological properties. The resulting ink is applied to a modified substrate using inkjet printing in 12 passes to form a homogeneous array of nanoparticles. This allows for the creation of a stable and reproducible structure that enhances the SERS signal. To study plasmonic characteristics, crystal violet (CV) dye with a concentration of 10 is used as an analyte. -6mol / L. Disadvantages of this method include the increased technological complexity of its implementation, and the use of paper as a substrate can lead to reduced sample stability and reproducibility. Furthermore, the described method is poorly scalable and is not compatible with the use of other conductive nano-objects as ink bases, such as metallic nanotubes, due to the potential for clogging of printing press nozzles when using nano-objects with a high aspect ratio, significantly limiting the applicability of this method in industrial and laboratory applications.

[0015] The objective of the invention is to develop a method for producing a matrix of plasmonic structures using a microplotter printing method with the use of functional inks containing metal nanowires.

[0016] The technical result of the invention is:

[0017] - implementation of selective formation of a matrix of plasmonic structures with specified lateral dimensions and spatial positioning on a substrate without the need for masks, which is achieved through localized application of functional inks containing metal nanowires using microplotter printing;

[0018] - increasing the uniformity of the thickness of the resulting coatings and, as a consequence, reducing the coefficient of variation of their characteristics when used as plasmonic structures;

[0019] - increasing efficiency and, accordingly, reducing the cost of end devices by minimizing the loss of expensive material (metal nanowires) through the use of microplotter printing as a method for forming plasmonic structures using functional inks.

[0020] The technical result is achieved by placing pre-prepared ink based on metallic (e.g., silver, copper, gold, etc.) nanowires into a microplotter's capillary dispenser. A matrix of plasmonic structures of the desired geometry is formed using microplotter printing on a substrate that has been previously degreased and cleaned with acetone and isopropyl alcohol. A wide range of materials can be used as a substrate, such as oxidized silicon, aluminum oxide, quartz, glass, etc. The resulting matrix of structures is then heat-treated in air to evaporate residual solvent, washed with formic acid diluted with isopropyl alcohol, and then heat-treated again in air.

[0021] Microplotter printing is a promising solution for creating arrays of plasmonic structures based on metallic nanowires. A key advantage of this technology is the ability to precisely target functional inks without the use of masks, enabling the creation of objects with the required geometric parameters, including complex geometries. An important technological parameter is the low coefficient of variation in the thickness of the resulting coatings (in the experiments, not exceeding 5-7%), ensuring high reproducibility of the characteristics of the printed elements when using the structures, for example, as signal amplifiers for SERS. Additional advantages include minimal consumption of expensive functional materials, compatibility with flexible substrates, and the ability to integrate into existing microelectronic device production lines.

[0022] In the proposed method for preparing ink based on metal nanowires, the concentration of the corresponding nanowires in the solution can vary from 0.1 to 0.5 wt%. The diameter of the metal nanowires can vary from 20 to 200 nm, while the length of the metal nanowires can range from 10 to 100 μm. The variability of the dimensional parameters of nanoobjects for the proposed method significantly exceeds the range of parameters for standard drop-on-demand inkjet printing, which, when working with long nanoscale objects, poses a high risk of clogging the nozzles of the cartridge. The resulting ink for printing is a dispersion based on metal nanowires in isopropyl alcohol as a solvent, containing a dissolved polymer binder.

[0023] During the preparatory stage, the substrate is cleaned and degreased using acetone and isopropyl alcohol. Various substrate materials can be used, including oxidized silicon, aluminum oxide, quartz, glass, polyethylene terephthalate, polyimide, and others. Functional ink containing metal nanowires is loaded into the capillary dispenser of the SonoPlot GIX Microplotter II microplotter printing system, followed by positioning the nozzle over the target area of ​​the substrate. Ink deposition occurs in contact printing mode, whereby an oscillating liquid meniscus is formed at the end of the capillary by applying an alternating voltage to a piezoelectric element attached to the capillary needle. Ink contact with the surface is established with a voltage amplitude of 5-12 V and a gap of 5-10 μm between the capillary and the substrate.After contact is established, the capillary moves along a programmable trajectory while simultaneously applying a reduced alternating voltage to the piezoelectric element for controlled material deposition. Upon completion of printing, the resulting matrices of plasmonic structures based on metal nanowires are heat-treated at 80-120°C in air for 20-60 minutes. The resulting samples are then treated with formic acid diluted with isopropyl alcohol to eliminate excess oxidation of the nanowires and improve their properties as a matrix for plasmonic structures. This is followed by further drying at 100°C in air for 10-30 minutes.

[0024] This method produces a matrix of plasmonic structures formed by microplotter printing using functional inks based on metal nanowires. Microplotter printing allows for the fabrication of elements with the desired geometry in the desired areas of the substrates. The deposited structures also exhibit a low coefficient of thickness variation, which positively impacts the reproducibility of the elements produced using this method. Furthermore, microplotter printing significantly reduces the consumption of expensive material (metal nanowires), leading to a reduction in the cost of the final product.

[0025] The invention is illustrated by the following examples:

[0026] Example 1. The method is implemented as follows. To form a matrix of plasmonic structures, a dispersion of silver nanowires with an average diameter of 50-60 nm and an average length of 20 μm is used in isopropanol with the addition of polyvinylpyrrolidone (PVP) to improve stability and a nanowire concentration of 0.5 wt%. Before printing, a smooth ceramic (aluminum oxide) substrate measuring 22 x 8 mm is cleaned and degreased using acetone and isopropyl alcohol. Then, silver nanowire-based ink is placed in the capillary dispenser of specialized SonoPlot GIX Microplotter II printing equipment, and the capillary nozzle is positioned at a distance of 5-10 μm from the substrate plane, 1 mm from the substrate corner both horizontally and vertically. A 10V AC control voltage is then applied to the piezoelectric element attached to the capillary dispenser, thereby facilitating contact between the ink and the substrate.After contact is established, the amplitude is reduced to 1 V and maintained at this value throughout the print. Ink is deposited by moving the capillary dispenser along a trajectory representing a meander with long sections of 3 mm and short sections of 300 μm. The dispenser movement speed is maintained at 10 mm / s. After layer formation is complete, the capillary dispenser is moved back along the same trajectory, ensuring uniform coverage of an area of ​​3 x 3 mm, resulting in the print ending at the same point where it began. After printing, the capillary dispenser is raised above the substrate surface by 200 μm and moved 5 mm along the long edge of the substrate, where the second element of the plasmonic structure array is printed in the same way as the first. It is then moved again 5 mm along the long edge of the substrate, and a third identical element of the plasmonic structure array is printed in the same way.The substrate with the printed matrix is ​​then heat-treated at 100°C in air for 30 minutes. The structures are then washed with formic acid diluted to a concentration of 10% by volume in isopropyl alcohol and heat-treated again in air at 100°C for 15 minutes. This produces a matrix of three identical plasmonic structures based on silver nanowires, which can be used, for example, to enhance the SERS signal.

[0027] Example 2 is similar to Example 1, but uses a 10 x 10 mm aluminum oxide substrate. In this case, four plasmonic structures based on silver nanowires measuring 3 x 3 mm are printed, each starting with a 1 mm horizontal and vertical offset from one corner of the substrate for each new structure. This results in a matrix of four identical plasmonic elements arranged symmetrically around the center of a square aluminum oxide substrate.

[0028] Example 3 is similar to Example 1, but a 20x20 mm quartz glass substrate is used. In this case, four lines of four 3x3 mm plasmonic structures based on silver nanowires are printed in each line. A 2 mm distance is maintained between each pair of adjacent structures, both horizontally and vertically. This results in a matrix of sixteen identical plasmonic structures.

[0029] Example 4 is conducted similarly to Example 1, but using a 15x15 mm silicon oxide substrate. In this case, four plasmonic nanowire structures measuring 5x5 mm are printed, each starting with a 1 mm horizontal and vertical offset from one corner of the substrate for each new structure. This results in a matrix of four identical plasmonic elements arranged symmetrically around the center of a square aluminum oxide substrate.

[0030] Example 5 is carried out similarly to Example 1, but copper nanowires with an average diameter of 80 nm and an average length of 25 μm in isopropanol with the addition of PVP and a nanowire concentration of 0.4 wt% are used as the ink base. Aluminum oxide with dimensions of 22 x 8 mm is used as the substrate. Printing is carried out similarly to Example 1, but after printing, drying is carried out in an air atmosphere at 80°C for 20 minutes. The structures are then washed using formic acid diluted to a concentration of 10 vol% in isopropyl alcohol and again subjected to heat treatment in air at 100°C for 15 minutes. This produces a matrix of three identical plasmonic structures based on copper nanowires.

[0031] Thus, using the microplotter printing method, a matrix of plasmonic structures based on metal nanowires is obtained, characterized by a high level of reproducibility and homogeneity of the resulting coatings, which can be used, for example, to enhance the SERS signal, fluorescence, photocatalytic reactions, or as a basis for solar cells, and in other fields.

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[0071] High-repeatability hydrophobic paper surface-enhanced Raman substrate, preparation method thereof and application of high-repeatability hydrophobic paper surface-enhanced Raman substrate in drug detection

Claims

1. A method for producing a matrix of plasmonic structures based on metallic nanowires, characterized in that functional ink based on metallic nanowires in isopropyl alcohol is placed in a capillary dispenser of a microplotter and a matrix of plasmonic structures of the required geometry is formed by microplotter printing on a substrate that has been previously degreased and cleaned using acetone and isopropyl alcohol, after which the resulting matrix of structures is subjected to heat treatment at a temperature of 80-120 °C in an air atmosphere for 20-60 minutes in order to evaporate the residual solvent and washed using formic acid, previously diluted with isopropyl alcohol, and then the sample is again subjected to heat treatment at a temperature of 100 °C in an air atmosphere for 10-30 minutes.

2. The method according to paragraph 1, characterized in that silver, copper, gold and other metal-based nanowires are used as metal nanowires for functional ink in a concentration range from 0.1 to 0.5 wt.%.