Electrically conductive nanocomposite layer on flexible substrate for producing flexible elastic conductors and method for producing it

Abstract

FIELD: medicine; nanotechnology; neural engineering.SUBSTANCE: electrically conductive two-layer nanocomposite material for the production of flexible elastic conductors and a method for producing it. The electrically conductive nanocomposite material consists of polydimethylsiloxane, in the upper part of which graphene nanoparticles are partially embedded, which are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm. To obtain an electrically conductive nanocomposite material, graphene nanoparticles are mixed with hexane. The resulting mixture is then treated with ultrasound to form a suspension and applied to the surface of the not fully cured polydimethylsiloxane. After this, the resulting electrically conductive two-layer nanocomposite material is dried until the hexane has completely evaporated.EFFECT: ensuring reliable fixation of nanoparticles, which are multilayer flakes of graphene, on the surface of the layer (in the upper part) of polydimethylsiloxane, as well as to prevent their spontaneous separation from the polydimethylsiloxane layer when the material is bent and when it is stretched up to 40% of the original length.12 cl, 5 dwg

Description

[0001] This group of inventions relates to medicine, nanotechnology, and neuroengineering. It comprises an electrically conductive bilayer nanocomposite material for the manufacture of flexible elastic conductors and a method for producing the same. The proposed electrically conductive bilayer nanocomposite material can be used to manufacture conductive elements and electrical contacts for soft electronic devices intended for implantation into the structures of a patient's central nervous system to restore its function.

[0002] STATE OF THE ART

[0003] Brain and spinal cord injuries, neurodegenerative diseases, and other diseases often lead to severe disability due to the impairment of sensory, motor, and cognitive functions. Conservative treatment and attempts at neurosurgical correction using standard methods are often ineffective. Therefore, the most promising approach currently considered to be the use of implantable neuroprosthetic systems based on neural machine interface technology, which enable data exchange between the human nervous system and electronic devices to restore impaired sensory, motor, and cognitive functions (Kravchenko SV et al., 2021) [1].

[0004] A neural interface, or brain-computer interface (BCI), is a device that allows the human brain to interact with external software or hardware, such as a computer or robotic arm, by reading the brain's bioelectrical activity and / or stimulating nervous system structures. There are three main types of neural interfaces: non-invasive, semi-invasive, and invasive. In non-invasive BCIs, electrodes are typically attached to the wearer's scalp, recording the brain's bioelectrical activity without direct contact with neural tissue. Semi-invasive BCIs make direct contact with the brain, but only on its surface, without inserting into the tissue. Invasive BCIs are inserted into the patient's brain tissue through complex surgery. Due to the high risks, invasive BCIs are currently used only when other options are unavailable—for example, for patients with severe conditions such as paralysis or blindness.Brain-computer interfaces are also divided by the direction of information transfer into unidirectional and bidirectional. The former are capable of reading brain signals (controlling robotic manipulators and prosthetic limbs) or solely stimulating the brain (bionic vision systems), while the latter are capable of simultaneously reading the brain's bioelectrical activity and transmitting signals from external electronic devices (sensory prosthetic limbs). Bidirectional invasive neural interfaces are the basis for neuroprosthetics designed to replace the functions of damaged nervous system structures (for example, an artificial hippocampus for memory restoration).

[0005] The most challenging and attention-grabbing aspect of neuroprosthesis development is ensuring reliable electrical contact between its electrodes and the nervous tissue while simultaneously preventing traumatic and toxic effects. The nervous tissue of the central nervous system is a relatively soft medium, characterized by a Young's modulus of approximately 1 kPa. Biological tissues with such mechanical properties are damaged when interacting with rigid electrode systems. Biologically active substances released from the damaged tissue cause local tissue restructuring, which leads to disruption of the electrical contact between the tissue and the electrodes and the loss of functionality of the neuroprosthesis (Feiner R., Dvir T., 2017) [2].

[0006] In this regard, in the development of modern invasive neuroprostheses, approaches based on the use of elastic soft electrode systems are becoming increasingly relevant.

[0007] Polydimethylsiloxane (PDMS) is a widely used silicone polymer. PDMS is optically transparent and generally inert, non-toxic, and non-flammable. Due to its biocompatibility, softness, and elasticity, it is widely used in various implantable medical devices (Kim S. H. et al., 2011) [3]. Being a dielectric, this material can be modified by incorporating nanoparticles with electrical conductivity, which allows the formation of conductive layers on a dielectric substrate made of polydimethylsiloxane.

[0008] Also known as graphene, a two-dimensional material that can be considered as a building block for sp 2 -hybridized allotropic forms of carbon of any other dimension. It can be assembled into three-dimensional graphite, twisted into one-dimensional nanotubes, or rolled into zero-dimensional fullerenes. Charge transport and their high mobility (2.5⋅10 5 cm 2 ⋅In-1 ⋅s -1 ) make it an ideal material for nanoelectronics, especially for high-frequency applications. In addition, its optical (optical absorption by one layer ≈ 2.3%), thermal (thermal conductivity coefficient 3000÷5000 W⋅m -1 ⋅K -1 ) and mechanical properties (Young's modulus ~1⋅10 12 Pa, intrinsic tensile strength ~1.3⋅10 11Pa) are ideal for micro- and nanomechanical systems, thin-film transistors, transparent and conductive composites and electrodes, flexible and printable (opto)electronics and photonics. The large specific surface area, chemical purity and the ability to change the functional properties by adding various molecules and compounds make graphene and its derivative, graphene oxide, also attractive materials for biotechnology and medicine. Along with single-layer graphene, bilayer graphene and graphene containing several (3÷5) layers, multilayer graphene (MLG), also called ultrathin graphite, is also attractive for research. Multilayer graphene is not significantly inferior to single-layer graphene in its electrical and thermal properties, the methods for its production are quite simple and scalable, and therefore it is a promising material for electronics [4].

[0009] Nanoparticles are any objects whose sizes in all three dimensions are from 1 to 100 nanometers (1 nm = 1×10 -9 Nanoparticles (m) are produced both through chemical synthesis and naturally. They are ubiquitous in nature and, in some cases, can be formed by living organisms, such as magnetosomes in some bacterial species or exosomes in eukaryotes. Due to their small size, nanoparticles possess a number of unique physical, chemical, and biological properties that are in demand in various fields of medicine.

[0010] Analysis of the state of the art and a search for publicly available sources of information revealed the closest analogues of the proposed group of inventions.

[0011] A method for producing a hybrid material based on a transparent conductive graphene film is known from patent document RU 2662535, July 26, 2018 [5]. The invention relates to electrical engineering, the chemical industry, and nanotechnology, and can be used in the manufacture of touch and liquid crystal screens, solar energy converters, and LEDs. First, natural graphite is heat treated and a suspension of natural graphite with a concentration of no more than 6 mg / ml is prepared in an aqueous medium, which may contain surfactants or dispersing agents. Then, ultrasonic treatment is carried out to obtain a suspension of few-layer graphene particles, which is dried in air at a temperature not exceeding 40-50°C.The resulting directly exfoliated graphene powder is redispersed in an ultrasonic bath with a power of at least 90 W for at least 15 min in an aqueous-organic medium consisting of a mixture of an organic solvent and water purified by reverse osmosis to a specific electrical conductivity of no more than 30 μS / cm. The resulting graphene suspension is centrifuged at room temperature with a total impact of at least 120,000 rpm, with a sediment weight of no more than 90% of the initial graphene suspension weight, and with a specific electrical conductivity of the graphene suspension of at least 80 μS / cm.A transparent conductive graphene suspension is applied using the Langmuir-Blodgett method to a piezoelectric substrate, which can be lithium niobate, PZT ceramics, quartz, or a piezoelectric polymer material such as polyvinylidene fluoride copolymer. The substrate has been pre-treated with chemical etching, solvent treatment with water, ethyl alcohol, acetone, hexane, and petroleum ether, and polished. The suspension is then dried at a residual pressure of no more than 10 mmHg and a temperature of no more than 120°C. More than one film can be applied to the substrate surface. The resulting transparent conductive graphene film is an X- or Y-type, a hybrid material with a light transmittance of at least 85% in the optical range of 400-800 nm and a surface electrical resistance at direct current of no more than 1 kOhm.

[0012] The disadvantage is that the films obtained by this method are not stretchable, which limits their use in the design of devices implanted in the body.

[0013] A method for producing films from multilayer graphene plates is known (Alaferdov A.V., 2016) [4]. The method involves liquid-phase exfoliation of natural graphite with crystallite sizes of 1-3 mm in organic solvents (isopropyl alcohol, N,N-dimethylformamide and N-methylpyrrolidone) in an ultrasonic bath with a power of 100 W and a frequency of 37 kHz for 4 hours. The resulting suspension with a concentration of 1 mg / ml is centrifuged for 90 min at 800 rpm in order to separate graphene plates with a lateral size of 1 to 4 μm. 40 vol.% of the suspension, collected with a syringe from the top, with a concentration of graphene plates of 0.134 mg / ml is used for further work. Thin continuous films consisting of multilayer graphene plates (or graphite nanoribbons) are obtained using a modified Langmuir-Blodgett method (in this method, the geometry of the Teflon cuvette and the location of the substrate attachment are changed compared to the commercial method).The modified Langmuir-Blodgett method is a method for forming thin films based on an array of carbon nanostructures. A substrate with a hydrophilic surface is attached vertically to the bottom of the cuvette sidewall. When creating a film from graphite nanoribbon (MGR), standard volatile solvents (benzene, toluene, chloroform, etc.) cannot be used, as they can cause the deposited material to form 3D structures on the water surface. A solution to this problem is the use of polar solvents such as NMP or DMF, which are commonly used to prepare graphene suspensions. After applying the suspension and evaporating (partially dissolving in water) the solvent for 10 minutes, a film of evenly distributed graphene sheets freely floating on the water surface is formed.Next, as the water slowly flows downward (the hole is located at the bottom of the cuvette), with a corresponding decrease in the surface area of ​​the water surface, which is ensured by the inclined wall of the cuvette, the MSG (graphite nanoribbon) platelets converge, forming an increasingly compact film. Then, as the water level slowly decreases, the formed film is deposited onto a vertically oriented substrate. Due to the special trapezoidal geometry of the cuvette (the wall of the cuvette opposite the sample is angled at 45°), the decrease in the surface area of ​​the water covered by the film, as the water flows out, precisely corresponds to the area of ​​the film deposited on the sample, maintaining constant surface tension, i.e., a constant film density throughout the entire deposition process.This method can be used to deposit CNS films on both solid (thermal silicon dioxide or glass) and flexible polymer substrates, such as polydimethylsiloxane (PDMS). It is important to note that the PDMS surface is hydrophobic, so substrate treatment is necessary to improve its hydrophilic properties. To impart hydrophilic properties, the polymer substrate was treated with capacitive RF discharge O2 plasma for 10 min (oxygen flow 10 cm). 3 / min at a pressure of 50 mTorr and a power of 300 W). The resulting surface electrical resistance values ​​for single-layer films can be reduced from 1600 Ohm / sq to 600 Ohm / sq by annealing in high vacuum (~10 -6 Torr) at a temperature of 900°C for one hour. The light transmittance (in the optical region) of the film after a single application is ~35% at a specific resistance of 40 kOhm / sq and decreases to 2.5% at a resistance of 150 kOhm / sq.

[0014] This method has the following disadvantages:

[0015] - use of toxic organic solvents in liquid-phase exfoliation of graphite;

[0016] - the need for hydrophilization of the substrate, associated with its treatment with aggressive chemical reagents, which complicates the use of the method for applying conductive films to polymer substrates;

[0017] the need for annealing of a single-layer film to achieve electrical resistance less than 1 kOhm / sq, which is inconsistent with the use of flexible polymer substrates;

[0018] - high electrical resistance of unannealed films 40 kOhm / sq.

[0019] A method for producing a bilayer structure in the form of a dielectric substrate made of polydimethylsiloxane having a composite layer in the form of silver nanoparticles dispersed in the polydimethylsiloxane matrix is ​​known (Kim JY, Jang KS, 2018) [7]. The method is as follows: silver nanoparticles with a diameter of <100 nm in an amount of 0.45 g are mixed with 0.285 g of a polymer base of polydimethylsiloxane and 0.015 g of a hardener in a mortar for 10 minutes, after which 2.5 g of toluene are added and mixed again in a mortar for 10 minutes. The resulting mixture weighing 3 g is poured into a foil cup with a diameter of 2 cm and kept at room temperature for 1 hour to precipitate the silver nanoparticles. The mixture was then annealed at 100°C on a hot plate for 2 hours to remove residual toluene. To obtain a bilayer structure, 1.1 g of uncured polydimethylsiloxane was poured onto the surface of the resulting composite and annealed at 150°C on a hot plate for over 20 hours.The thickness of the conductive composite layer in the resulting structure was ~200 μm.

[0020] The disadvantages of this method are:

[0021] - the use of silver as a filler for a composite. When such a material remains in the body for a long time, silver ions may diffuse beyond the composite;

[0022] - the use of extremely toxic toluene in large quantities relative to the total volume of the structures obtained;

[0023] - Over time, silver is subject to oxidation when exposed to tissue fluid, which can lead to deterioration of electrical contact with nerve tissue;

[0024] - a multi-stage, complex and lengthy receipt protocol;

[0025] - the curing of polydimethylsiloxane in the composite layer and the polydimethylsiloxane poured onto it to form a dielectric base occurs at different times, which may be the reason for the lower mechanical strength of the structure;

[0026] - Annealing at high temperatures increases the rigidity of polydimethylsiloxane, which makes such a material less compatible with the nervous tissue of the brain and spinal cord in terms of its mechanical properties.

[0027] A method for producing an electrically conductive layer on a polydimethylsiloxane substrate is known (Zhang R. et al. 2020) [8]. This method is implemented as follows: polydimethylsiloxane is dissolved in hexane in a ratio of 1:3 with stirring for 1 hour until a homogeneous solution is obtained. Then, nickel-plated graphite granules are added to the resulting solution and the resulting suspension is stirred for 1 hour. Next, a hardener is added to the mixture in a volume of 1:10 relative to the polydimethylsiloxane dissolved in hexane and the solution is poured into a square Teflon mold with a depth of 1 mm. The sample is allowed to settle for 2 hours, with the nickel-plated graphite particles settling to form a conductive layer at the bottom of the container, after which the film is cured in a heating chamber at 100 ° C for 45 minutes. The content of nickel-plated graphite in the resulting composite can vary, reaching up to 11.11 vol.%.

[0028] This method has disadvantages that make it impossible to use composites obtained by this method for use in devices intended for implantation into the body:

[0029] - nickel, which coats the graphite particles in this composite, can be toxic if left in the body for a long time;

[0030] - the need to pre-obtain nickel-plated graphite particles complicates the production technology of this material;

[0031] - a large amount of solvent - hexane - relative to the volume of polydimethylsiloxane can be potentially dangerous due to the possible risk of incomplete evaporation of the latter.

[0032] The closest analogue (prototype) of the proposed method for producing an electrically conductive bilayer nanocomposite material is the method for producing and electromechanically characterizing highly conductive multilayer flexible graphene sheets made of graphene / polydimethylsiloxane (Chiara Acquarelli et al., 2015) [6]. Multilayer graphene (MLG) micro- and nanosheets have been investigated for use as a nanofiller in polymer composite to obtain multifunctional materials with improved electrical conductivity and mechanical properties. In order to take advantage of the electrical conductivity properties of MLG sheets, a large amount of nanofiller should be used. Although, an increase in filler loading changes the mechanical properties of the composite due to severe filler agglomeration.A promising approach to creating an electrically conductive lightweight composite was demonstrated to be the incorporation of conductive graphene (GP) sheets, obtained by vacuum filtration of a nanofiller suspension, into a polymer matrix. One advantage of GP polymer infiltration is that the composite's tensile modulus can be significantly improved compared to GP or pure polymer, without weakening the electrical properties of the highly continuous nanofiller network formed during sheet fabrication. Experimental results related to the fabrication process and electromechanical behavior of free-standing, highly conductive MLG graphene sheets impregnated with polydimethylsiloxane (PDMS) were presented.Porous graphene-based sheets were prepared from MLG microsheets by thermal expansion of a graphite intercalated compound, sequential liquid-phase exfoliation of the resulting expanded graphite in a suitable solvent, and finally vacuum filtration of the MLG suspension using a nanoporous alumina membrane. Due to their porosity, MLG sheets can be impregnated with PDMS prepolymer to produce MLG / PDMS composites. The prepolymer base and crosslinking curing agent were mixed in a 10:1 volume ratio. All samples were mixed using a mechanical stirrer, and the mixed uncured PDMS was degassed to produce bubble-free test specimens. The degassed PDMS mixture was then centrifuged to obtain a layer thickness of ~376 μm. The MLG sheets were then impregnated with the uncured solution and then cured in an oven. Photographs of the MLG / PDMS composite in its as-prepared form and under bending are presented, demonstrating its good flexibility.Combined scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis of the resulting flexible MLG / PDMS composite shows that PDMS penetrates well into the porous structure of paper, thereby providing the resulting composite with flexibility and mechanical strength.

[0033] The disadvantages of this method are:

[0034] - complexity of the process due to the presence of a filtration stage;

[0035] - high cost aluminum nanoporous membranes have a high cost;

[0036] - potential toxicity of the resulting composites to nerve tissue due to the risk of aluminum oxide particles from the membrane entering the finished composite. Aluminum can have neurotoxic effects when retained in the body for long periods;

[0037] - absence of a dielectric layer - the composite is represented only by a monolayer conductive structure.

[0038] In this regard, there is a need for the following:

[0039] - develop a technology for applying graphene particles onto a flexible polydimethylsiloxane substrate that does not require the use of a filter deposition process;

[0040] - ensure reliable fixation of graphene particles on the surface of the polydimethylsiloxane substrate, eliminating their spontaneous separation from the product;

[0041] - ensure reliable fixation of graphene particles on the surface of the polydimethylsiloxane substrate, preventing their separation from the product when bent and stretched up to 40% of the original length.

[0042] The novelty of the claimed group of inventions, according to the authors, lies in the fact that for obtaining an electrically conductive two-layer nanocomposite material for the production of flexible elastic conductors, a method has been proposed based on the deposition of multilayer graphene flakes on the surface of incompletely cured PDMS from a dispersion of evaporating hexane solvent, which ensures reliable fixation of graphene nanoparticles on the surface of PDMS, and there is no spontaneous separation, nor separation from the surface of PDMS during bending and stretching.

[0043] As a result of the analysis of the state of the art, it can be concluded that the proposed group of inventions can be recognized as meeting the patentability criteria of “Novelty” and “Inventive step” before the date of the claimed priority.

[0044] DISCLOSURE OF THE INVENTION

[0045] To eliminate the shortcomings of known analogues, the applicant has proposed a group of inventions that characterize an electrically conductive two-layer nanocomposite material for the manufacture of flexible elastic conductors and a method for producing it.

[0046] The technical result from the implementation of the claimed group of inventions consists in obtaining an electrically conductive two-layer nanocomposite material intended for the manufacture of flexible elastic conductors, while ensuring reliable fixation of nanoparticles, which are multilayer flakes of graphene, on the surface of the layer (in the upper part) of polydimethylsiloxane, and also preventing their spontaneous separation from the polydimethylsiloxane layer when bending the material and when it is stretched up to 40% of the original length, which has not previously been used in the prior art.

[0047] OBJECT OF INVENTION

[0048] To solve a technical problem and achieve a technical result, the present group of inventions is proposed, which discloses an electrically conductive two-layer nanocomposite material for the manufacture of flexible elastic conductors and a method for producing it.

[0049] The specified technical result is achieved by a set of essential features presented in the invention formula.

[0050] In one non-limiting embodiment of the invention, a method is proposed for producing an electrically conductive two-layer nanocomposite material for the production of flexible elastic conductors, which comprises:

[0051] - mixing nanoparticles, which are graphene flakes, with hexane,

[0052] - processing the resulting mixture with ultrasound to obtain a suspension,

[0053] - applying the resulting suspension to the surface of not fully cured polydimethylsilyl sulfide,

[0054] - drying the obtained electrically conductive two-layer nanocomposite material until the hexane completely evaporates.

[0055] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which nanoparticles, which are graphene flakes, are mixed with hexane for 30-60 minutes or until the precipitate disappears.

[0056] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which the resulting mixture is treated with ultrasound for 30-60 minutes.

[0057] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which the resulting mixture is treated with an ultrasonic generator with a power of 150-200 W.

[0058] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which the resulting suspension is applied to the surface of incompletely cured polydimethylsiloxane, while the content of graphene flakes on the surface is provided in an amount of 0.8-1.2 mg per 1 cm 2 .

[0059] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which the resulting suspension is applied to the surface of incompletely cured polydimethylsiloxane using a dispenser.

[0060] In another embodiment, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which an incompletely cured polydimethylsiloxane is obtained by mixing a two-component silicone compound.

[0061] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which an incompletely cured polydimethylsiloxane is used, obtained after mixing a two-component silicone compound and maintaining it at room temperature for 20-24 hours.

[0062] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which an incompletely cured polydimethylsiloxane is obtained by mixing a two-component silicone compound including a hardener and a base in a ratio of 10:1.

[0063] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which nanoparticles are used that are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm.

[0064] In another example of implementation, a method for producing an electrically conductive two-layer nanocomposite material is proposed, in which polydimethylsiloxane with an applied suspension is dried under a hood at a temperature of +60 to +80°C until the hexane completely evaporates.

[0065] The technical result is also achieved due to the fact that an electrically conductive nanocomposite two-layer material is proposed, including a layer of polydimethylsiloxane and a layer of nanoparticles partially immersed in it, which are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm, located in the upper part of the polydimethylsiloxane layer.

[0066] BRIEF DESCRIPTION OF FIGURES, TABLES, AND OTHER GRAPHIC MATERIALS

[0067] Figure 1 shows a light microscopy micrograph of the surface of a sample of an electrically conductive nanocomposite bilayer material obtained by the method according to the proposed invention, the surface of which is completely covered with graphene particles in a continuous layer, with only individual light-transmitting areas.

[0068] Figure 2 shows a scanning electron micrograph of the surface of a sample of an electrically conductive nanocomposite bilayer material obtained by the method according to the proposed invention, which is completely covered with graphene plates oriented in different planes.

[0069] Figure 3 shows a scanning electron micrograph of a transverse fracture site of a frozen sample of an electrically conductive nanocomposite two-layer material obtained by the method according to the proposed invention.

[0070] Figure 4 shows a diagram of the expected distribution of graphene nanoparticles in the volume of the composite conductive layer (cross-section of the material sample).

[0071] Figure 5 shows a diagram of the arrangement of a mask for spraying contact pads onto a sample of an electrically conductive nanocomposite two-layer material obtained according to the proposed invention, for the purpose of measuring its electrical resistance.

[0072] DETAILED DESCRIPTION OF THE INVENTION

[0073] Definitions and General Terminology

[0074] References will now be made to specific embodiments of the invention, examples of which are illustrated by the proposed method and product. It is understood that the invention encompasses all alternatives, modifications, and equivalents that may be included within the scope of the present invention, as defined in the claims.

[0075] A person skilled in the art knows many methods and materials similar or equivalent to those described in this document, which can be used in the practical implementation of the present group of inventions.

[0076] The present invention is not limited to the methods and materials described herein. In the event that one or more of the incorporated literature references, patents, and similar materials differ from or conflict with this application, including, but not limited to, defined terms, use of terms, described techniques, etc., the present application shall prevail.

[0077] It should further be appreciated that certain features of the invention, which for clarity are described in the context of separate embodiments of the invention, may also be presented together in a single embodiment. Conversely, various features of the invention, which for brevity are described in the context of a single embodiment of the invention, may be presented separately or in any suitable subcombination.

[0078] When a range of values ​​is presented, it is understood that each intermediate value, up to tenths of a unit of the lower limit, unless the context clearly indicates otherwise, between the upper and lower limits of this range, and any other stated or intermediate values ​​within this stated interval are encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included within the smaller ranges, which is also within the scope of the invention, taking into account any specifically excluded limit in the stated range. When a range is stated to include one or both limits, ranges excluding either of both included limits are also within the scope of the invention.

[0079] All publications, patents, and patent applications are incorporated herein by reference. Although the invention has been described in the foregoing description with respect to certain preferred embodiments thereof, and many details have been set forth for illustrative purposes, it will be apparent to those skilled in the art that the invention admits of additional embodiments and that some details described herein may be significantly modified without departing from the spirit of the invention.

[0080] The use of singular terms in the context of the description of the invention shall be construed as covering both the singular and the plural unless otherwise indicated herein or clearly contradicted by context.

[0081] The terms “consisting of,” “having,” “including,” and “containing” shall be construed as open-ended terms, i.e., meaning “including but not limited to,” unless otherwise specified.

[0082] The use of any and all examples or illustrative language (e.g., "such as") provided herein is merely intended to better describe the invention and does not impose a limitation on the scope of the invention unless otherwise stated.

[0083] No wording in the description should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0084] Described herein are embodiments of this invention, including the best mode known to the inventors for carrying out the invention. Variations on these embodiments may become apparent to those skilled in the art upon reading the preceding description. The authors anticipate that skilled artisans will utilize such variations as circumstances dictate, and the authors contemplate that the invention will be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the features set forth in the appended claims, as permitted by applicable law. Furthermore, any combination of the above-described features in all their possible variations is encompassed by the invention, unless otherwise indicated herein or otherwise clearly contradicted by context.

[0085] The following terms are used to describe the present invention.

[0086] All technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains, unless otherwise defined. All patents and publications referenced herein are hereby incorporated by reference in their entirety.

[0087] The abbreviations used in the present description, including those given in the illustrative diagrams and the following examples, are well known to those of ordinary skill in the art.

[0088] Some of the terms and abbreviations used are as follows: Hexane is an organic substance, a saturated hydrocarbon belonging to the class of alkanes, used as an organic solvent.

[0089] Flexible elastic conductors are materials with electrically conductive properties that have mechanical characteristics that allow their shape to be changed by bending, twisting, stretching without destroying the sample and without losing its electrically conductive properties.

[0090] The two-component silicone compound used for producing cured polydimethylsiloxane used in the present invention is a silicone-based composition consisting of two separate components (usually a base polymer and a catalyst / curing agent) that, when mixed in a certain proportion, chemically react to form crosslinked (cured) polydimethylsiloxane (PDMS).

[0091] Multilayer graphene flakes are structures consisting of several (from 2 to ~10) graphene layers weakly bound together by van der Waals forces.

[0092] Soft electronic devices are flexible, elastic, and often stretchable electronic systems made of polymers, composite materials, or other soft conductive elements. They combine the functionality of traditional electronics with mechanical properties similar to biological tissue or soft materials. They can be used in soft robotics and implantable medical devices, particularly neuroprosthetics.

[0093] Nanoparticles (NPs) are any objects whose dimensions in all three dimensions or in one of the dimensions are from 1 to 100 nanometers (1 nm = 1×10 -9 m), obtained both by chemical synthesis and naturally. The present invention utilizes nanoparticles in the form of graphene powder or graphene flakes, which are a mixture of graphene nanoparticles with a size (thickness) of 3-30 nm.

[0094] A brain computer interface (BCI) is a device that allows the human brain to interact with external software or hardware, such as a computer or, for example, a robotic arm; this device reads the electrical activity of the brain and transmits it to an external device (usually a computer), where the signals are interpreted and associated with a specific action, allowing the wearer of the interface to turn their thoughts into actions, such as controlling the cursor of a computer mouse or a prosthetic arm.

[0095] A neuroprosthesis is a device designed for implantation into the central nervous system to restore, supplement, or replace its functions. Depending on the required functionality, it decodes signals from the bioelectric activity of neurons and / or stimulates them. Neuroprostheses are typically designed to restore sensory or motor functions; experimental studies are also underway to restore cognitive functions using neuroprostheses.

[0096] An ultrasonic bath is a device for creating cavitation in a liquid poured into a bath. It is a container made of stainless steel or other materials, to the bottom or walls of which ultrasonic transducers (emitters), usually piezoelectric, are attached. An alternating voltage of the appropriate frequency is supplied to the transducers from an electronic ultrasonic generator. The bath is typically used for ultrasonic cleaning of solids in cleaning solutions, but can also be used to accelerate physical and chemical processes in liquids (mixing, dissolving, emulsifying, extraction, disinfection, etc.).

[0097] A conductive nanocomposite bilayer material is a structure consisting of two layers: a flexible polymer base / substrate with a nanocomposite material in its upper layer, which is a polymer matrix containing nanoparticles of a conductive material (graphene nanoparticles are used in the present invention). These systems are designed to withstand mechanical deformations (bending, stretching, twisting) without loss of functionality.

[0098] PZT ceramics is a piezoelectric material based on lead zirconate titanate (Pb(Zr,Ti)O3).

[0099] DMF - solvent N,N-Dimethylformamide (dimethylformamide, DMF) is an organic compound with the formula (CH3)2NC(O)H.

[0100] kOhm kiloohm (kΩ) is a unit of electrical resistance equal to 1000 ohms, used in electronics and electrical engineering to express large resistance values, making it easier to calculate and analyze.

[0101] MSG is multilayer graphene, also called ultra-thin graphite, graphite nanoribbon, multilayer graphene (MLG) micro- and nanosheets.

[0102] Ohm (Ω) is a unit of measurement of the electrical resistance of a conductor through which an electric current passes.

[0103] Surfactants - surface-active substances - are chemical compounds that reduce the surface tension at the interface between phases (for example, a liquid and a solid, two different liquids, a liquid and a gas; as a rule, surfactants are organic compounds with an amphiphilic structure: their molecules contain polar (hydrophilic) and non-polar (hydrophobic) parts.

[0104] NMP - N-methyl-2-pyrrolidone (NMP) solvent.

[0105] PDMS – polydimethylsiloxane (PDMS) – is a silicone polymer with a wide range of applications. PDMS is optically transparent and generally inert, non-toxic, and non-flammable. It has a Young's modulus in the range of several MPa and is widely used in the development of implantable medical devices and flexible electronics. The present invention utilizes partially cured polydimethylsiloxane, obtained after curing with a curing agent at room temperature for 20-24 hours.

[0106] SEM - Scanning Electron Microscope (SEM) is a type of microscope designed to image and analyze materials by scanning a focused electron beam along the surface of the sample being examined.

[0107] UNS - a film of carbon nanowalls and graphene, is a porous material and consists of curved plates up to ~30 nm thick.

[0108] EDX - energy-dispersive X-ray.

[0109] GP - graphene paper (sheet, layer).

[0110] μm designation of micrometer (μm) - a fractional unit of length measurement, 1 μm is equal to 10 -6 meters or 10 -3 millimeters.

[0111] IMPLEMENTATION OF THE INVENTION

[0112] An electrically conductive nanocomposite two-layer material for the production of flexible elastic conductors and a method for producing it are proposed.

[0113] The proposed method for producing an electrically conductive two-layer nanocomposite material for the production of flexible elastic conductors consists of:

[0114] - mixing nanoparticles, which are multilayer graphene flakes, with hexane by stirring with a magnetic stirrer for 30-60 minutes or until the precipitate disappears;

[0115] - treating the resulting mixture with ultrasound for 1 hour in an ultrasonic bath with an ultrasonic generator power of at least 200 W until a suspension is obtained;

[0116] - applying the resulting suspension to the surface of incompletely (partially) cured polydimethylsiloxane using a dispenser, while incompletely cured polydimethylsiloxane is obtained by mixing a two-component silicone compound, including a hardener and a base in a ratio of 10:1, and keeping it at room temperature for 20-24 hours, which is a shorter period compared to the 48 hours usually recommended by the manufacturer for curing;

[0117] - drying the obtained nanocomposite layer with the applied suspension under a hood at a temperature of +60 to +80°C until the hexane has completely evaporated.

[0118] When implementing the proposed method, electrically conductive nanoparticles in the form of graphene powder or multilayer graphene flakes are used at a rate of 0.8-1.2 mg per 1 cm 2 by precipitating them from a dispersion of evaporating hexane solvent.

[0119] As a result of implementing the proposed method, an electrically conductive nanocomposite two-layer material is obtained for the production of flexible elastic conductors, consisting of a layer of polydimethylsiloxane and a layer of graphene flakes partially immersed in it, which are a mixture of electrically conductive nanoparticles with a size (thickness) of 3-30 nm, at a rate of 0.8-1.2 mg per 1 cm 2 , located in the upper part of the polydimethylsiloxane layer.

[0120] The essence of the claimed method for producing an electrically conductive nanocomposite layer on a flexible substrate made of polydimethylsiloxane, including the application of conductive nanoparticles by depositing them from a dispersion of an evaporating solvent, is that multilayer graphene flakes are used as conductive nanoparticles at a rate of 0.8-1.2 mg per 1 cm 2, which are dispersed in hexane by stirring with a magnetic stirrer for 30-60 minutes or until the precipitate disappears, followed by ultrasonic treatment for 30 minutes to 1 hour in an ultrasonic bath. An ultrasonic bath with an ultrasonic generator power of 150-200 W is used to disperse the graphene. After dispersion, the resulting suspension is applied to the surface of partially cured polydimethylsiloxane using a dispenser; the polydimethylsiloxane with the applied suspension is dried under a hood at a temperature of +60 to +80°C until the hexane completely evaporates.

[0121] The claimed method is implemented as follows. The polymer base of polydimethylsiloxane and the hardener (included in the two-component silicone compound) are mixed in a beaker in a volume ratio of 10:1. The beaker is placed in a vacuum oven for degassing, degassing is controlled visually by the absence of bubbles in the solution volume and on its surface. After degassing, the solution is poured into a Petri dish and left for 20-24 hours for incomplete, partial polymerization at a temperature of 18-24 ° C. Usually, the manufacturer's recommended time for complete curing of the mixture of polydimethylsiloxane and hardener is 48 hours. 2 hours before the end of partial polymerization of polydimethylsiloxane, begin to prepare a suspension of graphene particles in hexane. For this, a weighed amount of graphene is prepared based on the calculation of obtaining a layer containing about 0.8 1.2 mg of graphene per 1 cm 2A sample of graphene is transferred to a glass vial and 3 ml of hexane is added. A magnetic stirrer bar is placed in the vial, the vial is tightly capped to prevent hexane evaporation, and the mixture is stirred for 30-60 minutes or until the sediment at the bottom of the vessel has completely disappeared. The vial is then placed in an ultrasonic bath with an ultrasonic generator power of 150-200 W and sonicated for 30-60 minutes. The resulting suspension of graphene particles in hexane is applied using a dispenser to the surface of a partially cured polydimethylsiloxane substrate (PDMS) and placed in a Petri dish on a heating plate at a temperature of +60 to +80°C until the hexane has completely evaporated. Under the influence of hexane, swelling and partial dissolution of the top layer of the polydimethylsiloxane substrate occurs, due to which the graphene particles are immersed in the top layer of the substrate, becoming covered with a thin layer of polydimethylsiloxane.

[0122] Samples of the electrically conductive bilayer nanocomposite material (composite) obtained using the proposed method were studied using light and electron microscopy. In addition, their electrical resistivity was measured.

[0123] Light microscopy results showed that the composite surface was completely covered by a continuous layer of graphene particles, with only a few light-transmitting areas (Fig. 1). The average substrate coverage area with graphene particles was 97.61±0.18%. These light microscopy data were confirmed by scanning electron microscopy examination of the surface of the resulting composite samples. Figure 2 shows that the composite surface is completely covered by graphene plates oriented in different planes. It is noteworthy that the plates themselves have smoothed contours and are connected by bridges, indicating that they are likely coated with a thin layer of polydimethylsiloxane, which ensures their secure adhesion to the substrate surface.

[0124] To assess the thickness of the graphene layer on the substrate, composite samples were frozen in liquid nitrogen and fractured, with preparations of the fracture sites for scanning electron microscopy. It was found that the graphene-containing layer reached a thickness of 20-30 μm (Fig. 3).

[0125] The observed effects can be caused by partial dissolution of the surface of the polydimethylsiloxane substrate 1 with hexane with partial immersion of the graphene plates 2 into its upper layer 3 (Fig. 4).

[0126] To evaluate the resistivity of the obtained sample, a rectangular fragment measuring 10 x 20 mm was cut out (Fig. 5). A square mask 4, measuring 10 x 10 mm, was applied to the center so that rectangular free fields 5, each 5 mm wide, remained on both sides of the square. The resulting structure was attached using carbon tape in the chamber of a vacuum sputtering unit and a 20 nm gold-palladium coating was deposited in argon plasma. After sputtering, the mask was removed, leaving a sample in the form of a square composite fragment with two metallized contact pads. To measure the resistance, the terminals of a digital multimeter were placed on the contact pads of the sample, after which the resistivity was calculated based on the obtained resistance using the following formula:

[0127] ,

[0128] where: ρ is the specific resistance (Ohm*m), R is the electrical resistance of the sample (Ohm), S is the cross-sectional area of ​​the sample (m2), and L is the length of the sample (m). To calculate the specific electrical resistance, the thickness of the conductive composite layer was taken into account, rather than the entire substrate. With a layer thickness of 25 μm, the specific resistance is approximately 3.5 Ohm*m.

[0129] The invention is based on the observation that hexane applied to the surface of incompletely cured PDMS causes it to swell and partially dissolve at the point of contact with the solvent, which can be used to introduce nanoparticles into the polymer matrix so that they form a composite layer on the surface of the PDMS substrate.

[0130] It was demonstrated that the claimed technical result is achieved from the implementation of the proposed group of inventions, which consists in obtaining an electrically conductive two-layer nanocomposite material intended for the manufacture of flexible elastic conductors, while ensuring reliable fixation of nanoparticles, which are multilayer flakes of graphene, on the surface of the layer (in the upper part) of polydimethylsiloxane, and also preventing their spontaneous separation from the polydimethylsiloxane layer when the material is bent and when it is stretched up to 40% of the original length.

[0131] The essence and industrial applicability of the claimed group of inventions are explained by the following examples, without in any way diminishing the claims under the invention formula in all particular forms of embodiment of the features.

[0132] EXAMPLES

[0133] Example 1. Obtaining a sample of electrically conductive nanocomposite bilayer material containing 1 mg of graphene flakes per 1 cm 2 surface, and measuring its resistance

[0134] The procedure is carried out according to the proposed method. The polydimethylsiloxane polymer base and the hardener (included in the two-component silicone compound) were mixed in a beaker at a volume ratio of 10:1, after which the beaker was placed in a vacuum oven for degassing. Degassing was monitored visually by checking for the absence of bubbles in the solution and on its surface. After degassing, the solution was poured into a Petri dish and left for 24 hours for partial polymerization at room temperature. A graphene sample was prepared at a rate of 1 mg of graphene per 1 cm. 2Material. Nanoparticles consisting of a mixture of multilayer graphene flakes with a flake thickness of 3-30 nm were used. The prepared graphene sample was transferred to a glass vial, 3 ml of hexane was added, and a magnetic stirrer was placed in the vial. The graphene and hexane were stirred for 30 minutes, after which the vial was placed in an ultrasonic bath. The mixture was sonicated at an ultrasonic generator power of 150 W for 1 hour. The resulting suspension of graphene particles in hexane was applied using a dispenser to the surface of a partially cured polydimethylsiloxane (PDMS) substrate, and the Petri dish was placed on a hot plate heated to 60°C, holding until the hexane completely evaporated.As a result, the proposed method was used to obtain an electrically conductive nanocomposite two-layer material (composite), including a layer of polydimethylsiloxane and a layer of partially immersed nanoparticles, which are multilayer graphene flakes, with a flake thickness of 3-30 nm, located in the upper part of the polydimethylsiloxane layer.

[0135] After this, a sample measuring 10×20 mm was cut out from the film of the obtained composite for resistance measurement. A 10*10 mm square mask was applied to the center of each fragment in such a way that rectangular free fields, each 5 mm wide, remained on both sides of the square (see Fig. 5, the oblique hatching shows the location of the mask - 4, the solid color shows the open areas of the conductive surface of the composite - 5). The resulting structure was attached to the chamber of the Q150T sputtering unit (Quorum Technologies Ltd, UK) using carbon tape and sputtered with a 20 nm gold-palladium coating in argon plasma. After sputtering, the mask was removed, and a sample was obtained in the form of a square fragment of the composite with two contact pads. The probes of a digital multimeter were placed on the contact pads of the sample to measure the electrical resistance, which was 140 kOhm.

[0136] Example 2. Obtaining a sample of electrically conductive nanocomposite bilayer material containing 0.8 mg of graphene flakes per 1 cm 2 surface, and measuring its resistance to stretching by 20%

[0137] The procedure is carried out according to the proposed method. The polymer base of polydimethylsiloxane and the hardener (included in the two-component silicone compound) were mixed in a beaker in a volume ratio of 10:1, after which the beaker was placed in a vacuum oven for degassing. Degassing was monitored visually by the absence of bubbles in the solution and on its surface. After degassing, the solution was poured into a Petri dish and left for 20 hours for partial polymerization at room temperature. A graphene sample was prepared at a rate of 0.8 mg of graphene per 1 cm 2Material. Nanoparticles consisting of a mixture of multilayer graphene flakes with a flake thickness of 3-30 nm were used. The prepared graphene sample was transferred to a glass vial, 3 ml of hexane was added, and a magnetic stirrer was placed in the vial. The graphene and hexane were stirred for 40 minutes, after which the vial was placed in an ultrasonic bath. The mixture was sonicated at an ultrasonic generator power of 200 W for 45 minutes. The resulting suspension of graphene particles in hexane was applied using a dispenser to the surface of a partially cured polydimethylsiloxane (PDMS) substrate, and the Petri dish was placed on a hot plate heated to 70°C, holding until the hexane completely evaporated.As a result, the proposed method was used to obtain an electrically conductive nanocomposite two-layer material (composite), including a layer of polydimethylsiloxane and a layer of partially immersed nanoparticles, which are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm, located in the upper part of the polydimethylsiloxane layer.

[0138] Then, to measure the resistance under 20% stretching of the sample, a sample measuring 10 x 20 mm was cut out from the film of the obtained composite. A 10 x 10 mm square mask was applied to the center of each fragment in such a way that rectangular free fields of 5 mm in width each remained on both sides of the square (see Fig. 5, the oblique hatching shows the location of the mask - 4, the solid color shows the open areas of the conductive surface of the composite - 5). The resulting structure was attached to the chamber of the Q150T sputtering system (Quorum Technologies Ltd, UK) using carbon tape and sputtered with a 20 nm gold-palladium coating in argon plasma. After sputtering, the mask was removed, and a sample in the form of a square composite fragment with two contact pads was obtained. The resulting sample was fixed in the clamps of a Lincam MFS deformation cell (Lincam, UK), with the contact pads insulated from the cell clamps by pads made of dielectric material.The sample was stretched to 20% of its original length, after which digital multimeter probes were applied to the free portions of the sample's contact pads and the electrical resistance was measured, which was 344 kOhm. No separation of the graphene plates from the substrate was observed when stretched to this value.

[0139] Example 3. Obtaining a sample of electrically conductive nanocomposite bilayer material containing 1.2 mg of graphene flakes per 1 cm 2 surface and measuring its resistance to stretching by 40%

[0140] The procedure is carried out according to the proposed method. The polydimethylsiloxane polymer base and the hardener (included in the two-component silicone compound) were mixed in a beaker at a volume ratio of 10:1, after which the beaker was placed in a vacuum oven for degassing. Degassing was monitored visually by checking for the absence of bubbles in the solution and on its surface. After degassing, the solution was poured into a Petri dish and left for 22 hours for partial polymerization at room temperature. A graphene sample was prepared at a rate of 1.2 mg of graphene per 1 cm. 2Material. Nanoparticles consisting of a mixture of multilayer graphene flakes with a flake thickness of 3-30 nm were used. The prepared graphene sample was transferred to a glass vial, 3 ml of hexane was added, and a magnetic stirrer was placed in the vial. The graphene and hexane were stirred for 60 minutes, after which the vial was placed in an ultrasonic bath. The mixture was sonicated at an ultrasonic generator power of 170 W for 30 minutes. The resulting suspension of graphene particles in hexane was applied using a dispenser to the surface of a partially cured polydimethylsiloxane (PDMS) substrate, and the Petri dish was placed on a hot plate heated to 80°C, holding until the hexane completely evaporated.As a result, the proposed method was used to obtain an electrically conductive nanocomposite two-layer material (composite), including a layer of polydimethylsiloxane and a layer of partially immersed nanoparticles, which are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm, located in the upper part of the polydimethylsiloxane layer.

[0141] Next, to measure the resistance of the sample under 40% stretching, a sample of 10 × 20 mm in size was cut out from the film of the obtained composite. A 10 * 10 mm square mask was applied to the center of each fragment in such a way that rectangular free fields of 5 mm in width each remained on both sides of the square (see Fig. 5, the oblique hatching shows the location of the mask - 4, solid color - open areas of the conductive surface of the composite - 5). The resulting structure was attached to the chamber of the Q150T sputtering system (Quorum Technologies Ltd, UK) using carbon tape and sputtered with a 20 nm gold-palladium coating in argon plasma. After sputtering, the mask was removed, and a sample in the form of a square composite fragment with two contact pads was obtained. The resulting sample was fixed in the clamps of a Lincam MFS deformation cell (Lincam, UK), with the contact pads insulated from the cell clamps by pads made of dielectric material.The sample was stretched to 40% of its original length, after which digital multimeter probes were applied to the free portions of the sample's contact pads and the electrical resistance was measured, which was 2.5 megohms. No separation of the graphene plates from the substrate was observed after stretching to this value.

[0142] In the present examples of the invention, the authors have demonstrated that the claimed technical result is achieved, which consists in creating an electrically conductive two-layer nanocomposite material intended for the production of flexible elastic conductors, while ensuring reliable fixation of nanoparticles, which are multilayer flakes of graphene, on the surface of the layer (in the upper part) of polydimethylsiloxane, and also ensuring the prevention of their spontaneous separation from the polydimethylsiloxane layer when the material is bent and when it is stretched up to 40% of the original length.

[0143] To summarize the above, the group of inventions can be recognized as meeting the patentability criterion “Industrial applicability” in all particular forms of embodiment of the features of the invention formula up to the date of the claimed priority.

[0144] References:

[0145] 1. Kravchenko SV et al. "Cognitive neuroprosthetics: the path from experiment to clinical application", Innovative Medicine of Kuban, 2021;(3):64-72, https: / / doi.org / 10.35401 / 2500-0268-2021-23-3-64-72.

[0146] 2. Feiner R., Dvir T. “Tissue-electronics interfaces: from implantable devices to engineered tissues” / / Nature Reviews Materials, 2017, vol. 3. No. 1, p. 1-16.

[0147] 3. Kim SH et al. “Flexible, stretchable and implantable PDMS encapsulated cable for implantable medical device” / / Biomedical Engineering Letters, 2011, vol. 1, p. 199-203.

[0148] 4. Alaferdov AB “Study of the processes of formation and properties of structures based on multilayer graphene and multi-walled carbon nanotubes” / / diss. for a Ph.D. in Phys. and Mathematics, Nizhny Novgorod, 2016.

[0149] 5. Patent RU 2662535 (Joint-Stock Company ''Research Institute of Graphite-Based Structural Materials ''NIIgrafit'' (RU)), 07 / 26 / 2018 "Method for producing a hybrid material based on a transparent conductive graphene film."

[0150] 6. Chiara Acquarelli et al. “Manufacture and electromechanical characterization of highly conductive multilayer-graphene / polydimethylsiloxane flexible paper”, Conference: GraphIta2015At: CNR Bologna, Italy, September 2015 (prototype).

[0151] 7. Kim JY, Jang KS “Facile fabrication of stretchable electrodes by sedimentation of Ag nanoparticles in PDMS matrix” / / Journal of Nanomaterials, 2018, No. 1, https: / / doi.org / 10.1155 / 2018 / 4580921.

[0152] 8. Zhang R. et al. «Facile one-step preparation of laminated PDMS based flexible strain sensors with high conductivity and sensitivity via filler sedimentation)) / / Composites Science and Technology, 2019, 186:107933, DOI:10.1016 / j.compscitech.2019.107933.

[0153] 9. Chen Z. et al. «Sandwich-structured flexible PDMS@graphene multimodal sensors capable of strain and temperature monitoring with superlative temperature range and sensitivity)) / / Composites Science and Technology, December 2022, 232(35): 109881, DOI:10.1016 / j.compscitech.2022.109881.

Claims

1. A method for producing an electrically conductive two-layer nanocomposite material for the production of flexible elastic conductors, which involves: mixing nanoparticles, which are multilayer flakes of graphene, with hexane, using nanoparticles, which are a mixture of multilayer flakes of graphene with a flake thickness of 3-30 nm, processing the resulting mixture with ultrasound to obtain a suspension, applying the resulting suspension to the surface of incompletely cured polydimethylsiloxane, drying the resulting electrically conductive two-layer nanocomposite material until the hexane has completely evaporated.

2. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, which involves mixing nanoparticles, which are graphene flakes, with hexane for 30-60 minutes or until the precipitate disappears.

3. A method for producing an electrically conductive two-layer nanocomposite material according to paragraph 1, in which the resulting mixture is treated with ultrasound for 30-60 minutes.

4. A method for producing an electrically conductive two-layer nanocomposite material according to paragraph 1, in which the resulting mixture is treated with an ultrasonic generator with a power of 150-200 W.

5. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, in which the resulting suspension is applied to the surface of incompletely cured polydimethylsiloxane, wherein the content of graphene flakes on the surface is provided in an amount of 0.8-1.2 mg per 1 cm 2 .

6. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, in which the resulting suspension is applied to the surface of incompletely cured polydimethylsiloxane using a dispenser.

7. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, wherein the incompletely cured polydimethylsiloxane is obtained by mixing a two-component silicone compound.

8. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, which uses incompletely cured polydimethylsiloxane obtained after mixing a two-component silicone compound and maintaining it at room temperature for 20-24 hours.

9. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, wherein the incompletely cured polydimethylsiloxane is obtained by mixing a two-component silicone compound including a hardener and a base in a ratio of 10:

1.

10. A method for producing an electrically conductive two-layer nanocomposite material according to claim 1, in which nanoparticles are used that are multilayer flakes of graphene.

11. A method for producing an electrically conductive two-layer nanocomposite material according to paragraph 1, in which the polydimethylsiloxane with the applied suspension is dried under a hood at a temperature of 60 to 80°C until the hexane has completely evaporated.

12. An electrically conductive nanocomposite two-layer material for the production of flexible elastic conductors, obtained by the method according to any of paragraphs 1-11, comprising a layer of polydimethylsiloxane and a layer of nanoparticles immersed therein, which are a mixture of multilayer graphene flakes, with a flake thickness of 3-30 nm, located in the upper part of the polydimethylsiloxane layer.

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