A wet environment stable patterned pedot / pss conductive coating and its preparation method and application

Abstract

The application discloses a wet environment stable patterned PEDOT / PSS conductive coating and a preparation method and application thereof, and the preparation of the coating comprises the following steps: dissolving polycation, zwitterionic monomer, double bond silane and initiator to obtain solution component A, and diluting PEDOT / PSS as solution component B; and the component A and the component B are deposited on the surface of a substrate covered with a patterned mask plate through double-channel ultrasonic atomization spraying to obtain the coating. In the application, the polycation, the zwitterionic monomer and the double bond silane are used as the component A, and the PEDOT / PSS is combined to prepare the conductive coating, the coating has extremely high wet environment stability, can guarantee that the coating does not fall off in a physiological environment, and has excellent biocompatibility and immunocompatibility, and can improve the long-term performance of an implantable bioelectronic device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical coating materials, and particularly relates to a wet environment stable patterned PEDOT / PSS conductive coating and a preparation method and application thereof. BACKGROUND

[0002] Conductive polymers have shown great potential in bioelectronics due to their excellent electrical conductivity, mechanical flexibility, and biocompatibility. Among them, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), polypyrrole (PPy), and polyaniline (PAni) have been widely used in flexible bioelectrodes, neural interfaces, cardiac sensors, electronic skins, and implantable medical devices. These materials can work stably at low potentials and effectively transmit signals to human tissues, playing a key role in brain-computer interfaces, cardiac pacemakers, and electrical stimulation therapy. However, these conductive polymers have inherent defects in a humid physiological environment, especially during long-term use, often showing poor substrate adhesion and stability. Due to the penetration of water molecules and the peeling of the interface layer, the conductive layer is prone to delamination, swelling, and even falling off, severely affecting the reliability and service life of the device. Therefore, how to improve the adhesion, stability, and durability of conductive polymers in complex physiological environments is an important challenge in the research of bioelectronic materials.

[0003] In addition, high-resolution patterning of conductive coatings is still a technical challenge in the field of bioelectronics. Bioelectronic devices often require millimeter to nanometer precision patterning structures to optimize their electrical properties, biocompatibility, and interface matching between the device and biological tissue. However, most current PEDOT:PSS coating manufacturing methods have limitations, such as complex process steps, long processing cycles, and difficulty in adapting to large-area and flexible substrates. In addition, some patterning methods rely on chemical cross-linking or additive-induced processes, and these chemicals often have certain cytotoxicity, requiring a long time for detoxification, limiting their direct application in biomedical fields. Therefore, developing a simple, efficient, non-toxic, and high-resolution PEDOT:PSS hydrogel patterning process is crucial for the manufacture of bioelectronic devices.

[0004] CN104212243A discloses a preparation method of PEDOT / PSS conductive ink and coating. Acidic PEDOT / PSS dispersion or neutralized PEDOT / PSS dispersion is added with a thickening agent to achieve the required viscosity of the ink. PEDOT / PSS conductive coating is obtained by coating with these conductive inks. However, this coating has almost no force with the substrate, so it is easily detached, causing device failure.

[0005] CN117904681A discloses a method for preparing an aluminum alloy surface PEDOT conductive coating. An anion electrolyte and a prepolymer monomer are dissolved in acetonitrile to prepare a coating polymerization solution, and then a surface-treated aluminum alloy substrate is immersed in the deoxygenated coating polymerization solution. By adjusting the output current density, the aluminum alloy surface oxide film is broken as soon as possible, and then the substrate surface rapidly realizes the rapid and uniform deposition of PEDOT, and a dense and flat PEODT coating is obtained. However, this electrochemical deposition of PEDOT has the disadvantages of easy de-embedding of dopant, easy degradation of molecular chain, poor environmental tolerance, insufficient bonding force with the substrate, and low process repeatability, and high-resolution patterning cannot be achieved. SUMMARY

[0006] The present application aims to solve the problems of poor stability of PEDOT / PSS conductive coating in a wet environment and difficulty in high-resolution patterning, and provides a method for preparing a wet environment stable patterned PEDOT / PSS conductive coating. The PEDOT / PSS conductive coating prepared by the method has excellent interfacial adhesion to the substrate, can maintain the stability of the coating under harsh conditions, and the high-resolution patterning (<20 μm) capability gives the conductive coating potential application in the field of bioelectronics.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0008] A method for preparing a wet environment stable patterned PEDOT / PSS conductive coating, comprising the steps of:

[0009] Step 1: plasma or ozone activation treatment of the substrate;

[0010] Step 2: dissolving polycation, zwitterionic monomer, double-bonded silane and initiator to obtain solution component A, and diluting PEDOT / PSS as solution component B;

[0011] Step 3: depositing components A and B on the surface of the substrate covered with a patterned mask plate by double-channel ultrasonic atomization spraying to obtain a coating;

[0012] Step 4: polymerizing the substrate containing the coating under saturated humidity to obtain the patterned PEDOT / PSS conductive coating.

[0013] In the present application, a large number of polyanion electrolyte PSS exist in the PEDOT / PSS conductive polymer used, and the introduction of polycation can promote the crosslinking of these strong anions through electrostatic interaction. The surface of the substrate treated by plasma has a large number of negative charges, which can fully combine with the polycation, further improving the non-covalent interaction between the coating and the substrate.

[0014] The double bond silane and the zwitterionic monomer in the system can be initiated to polymerize to form a polyzwitterion by the initiator, on the one hand, the double bond silane introduces a covalent interaction between the substrate and the coating, at the same time, the anion-pi interaction between the polyzwitterion and the PSS further stabilizes the coating, and the preparation of a patterned coating with a precision of up to 20 mu m can be realized by combining ultrasonic spraying and a mask plate, which can be applied to the preparation of various bioelectronics, including brain-computer interface electrodes, cardiac pacemaker electrodes, electrical stimulation therapy electrodes, etc.

[0015] More importantly, the polyzwitterion used in the application has excellent immunocompatibility, which can improve the overall compatibility of the coating, and can avoid the occurrence of foreign body reaction after being implanted in the body (foreign body reaction will lead to the isolation of the implant from the body, which has become one of the important factors leading to the failure of bioelectronics). In general, the PEDOT / PSS conductive coating with stability, biocompatibility and high-precision patterning has broad application prospects.

[0016] The polycation includes any one or more of chitosan, polyethyleneimine, polydimethyl diallyl ammonium chloride, polyallylamine hydrochloride, polylysine, polyquaternary ammonium salt, and copolymers or derivatives thereof;

[0017] The zwitterionic monomer includes one or more of sulfobetaine methacrylate, carboxybetaine methacrylate, and methacryloyloxyethyl phosphorylcholine;

[0018] The double bond silane includes one or more of 3-acryloyloxypropyl triethoxysilane, 3-methacryloyloxypropyl trimethoxysilane, and allyl triethoxysilane;

[0019] The initiator includes one or more of ammonium persulfate, potassium persulfate, azobisdimethylvaleronitrile dihydrochloride, and azobisdimethylpropylamine dihydrochloride.

[0020] In the solution component A, the mass fraction of the polycation component is 0.01-1% of the total solution mass, the mass fraction of the zwitterionic monomer is 0.5-3% of the total solution mass, the mass fraction of the double bond silane is 0.01-0.1% of the total solution mass, and the mass fraction of the initiator is 0.01-0.1% of the total solution mass.

[0021] In the solution component B, the mass fraction of PEDOT / PSS is 0.1-0.5 wt%, preferably, the mass fraction of PEDOT / PSS is 0.2-0.4 wt%.

[0022] The solvent of the solution component A and the solution component B includes one or more of water and ethanol.

[0023] Preferably, the solvent is a water / ethanol mixed solvent, wherein the volume ratio of water to ethanol is 1:1~3;

[0024] Preferably, a small amount of DMSO is added before dilution of PEDOT / PSS to improve the conductivity and stability of the coating, and the amount of DMSO added is 5-20% of the volume of the PEDOT / PSS solution.

[0025] The flow rate of component A and component B in step 3 is 5~100μL / min; the flow rate ratio of component A to component B is 1:1~10. Preferably, the flow rate ratio of component A to component B is 1:2-8, and further preferably the flow rate ratio is 1:2-6. The more component A, the better the stability of the coating, but the conductivity of the coating decreases. The more component B, the better the conductivity, and the stability decreases accordingly.

[0026] In step 3, the temperature of the substrate during spraying is 50-70℃. Within this temperature range, the volatile solvent in the system quickly volatilizes, promoting the rapid and sufficient mixing of components A and B, and promoting the polymerization of the zwitterionic monomer.

[0027] In step 4, polymerization refers to the coating-containing substrate being placed in a saturated humidity at 70-90℃ for 1-4h. On the one hand, it is to promote the coupling of the silane coupling agent with the substrate or the coupling of the silane coupling agent with the silane coupling agent to form crosslinking points. On the other hand, it is also to promote the further polymerization of the SBMA monomer to improve the conversion rate.

[0028] The substrate includes any of the following materials:

[0029] (1) Metal materials: any of stainless steel, titanium and its alloys, cobalt-based alloys, nickel-titanium alloys, magnesium and its alloys, zinc and its alloys, iron and its alloys; or,

[0030] (2) Inorganic materials: any of glass, silicon dioxide, titanium dioxide, carbon materials, silicon, titanium nitride; or,

[0031] (3) High polymer materials: any of polyester, polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride, polystyrene and their copolymers or derivatives.

[0032] Preferably, the substrate material is at least one of silicone rubber, polyester, and polyurethane. All of the above are commonly used materials for implantable bioelectronics.

[0033] In step 1, the plasma or ozone activation time is 1~60min. Activation treatment is to increase the density of hydroxyl groups on the surface of the substrate, which is more conducive to the subsequent grafting of siloxane and the construction of a negative surface to promote the non-covalent binding of polycations to the surface.

[0034] The present invention also provides a patterned PEDOT / PSS conductive coating that is stable in a wet environment obtained by the preparation method described above.

[0035] The present invention also provides the application of the patterned PEDOT / PSS conductive coating in the preparation of bioelectrodes.

[0036] Preferably, the bioelectrode is an implantable bioelectrode, such as a brain electrode, a pacemaker electrode, or an electrical stimulation therapy electrode.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) In this invention, polycationic, zwitterionic monomers and double-bonded silanes are used as component A, and PEDOT / PSS is combined to prepare a conductive coating. The coating has extremely high stability in a wet environment, can ensure that the coating does not fall off in a physiological environment, and exhibits excellent electrochemical stability, and can be used for a long time.

[0039] (2) The present invention uses dual-channel ultrasonic atomization spraying technology to successfully prepare a high-precision patterned PEDOT / PSS conductive coating. After ultrasonic atomization, components A and B will spontaneously agglomerate to form uniform microdroplets during the spraying process. These special-shaped droplets can accurately pass through the fine structure of the high-precision mask and finally deposit a patterned coating on the substrate surface. The precision can be stably controlled at about 20μm, which significantly improves the pattern fineness and preparation reliability of the conductive coating.

[0040] (3) The PEDOT / PSS conductive coating prepared by the present invention has excellent biocompatibility and immunocompatibility, which can improve the long-term performance of implantable bioelectronics. Attached Figure Description

[0041] Figure 1 The thicknesses of the PP, PPE, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1 are shown under dry and wet conditions.

[0042] Figure 2 The water contact angles are those of the PP, PPE, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1.

[0043] Figure 3 The surface modulus of the PP, PPE, PPES1, and PPES3 coatings prepared in Example 1 and Comparative Example 1 is given.

[0044] Figure 4 The electrical conductivity of the PP, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1 ( Figure 4The change of the conductivity of the middle (A) and the coating with the time of immersion in PBS solution Figure 4 The middle (B).

[0045] Figure 5 The change of the charge storage density of the coating prepared for Example 1 and Comparative Example 1 after 10 min of ultrasonic treatment and the statistical data thereof, Figure 5 The middle (A) is a PP coating, Figure 5 The middle (B) is a PPE coating, Figure 5 The middle (C) is a PPES1 coating, Figure 5 The middle (D) is a PPES2 coating, Figure 5 The middle (E) is a PPES3 coating, Figure 5 The middle (F) is the statistical data of each coating.

[0046] Figure 6 The patterned coating prepared according to the parameters of PPES1 in Example 1 combined with different forms of mask plate, Figure 6 The middle (A) is the pattern of the interdigital electrode coating, Figure 6 The middle (B) is the pattern of the butterfly pattern coating.

[0047] Figure 7 The statistical diagram of the charge storage density of the PP, PPE and PPES1 coatings in Application Example 1 after 5000 cycles of cyclic voltammetry test.

[0048] Figure 8 The results of the 180° peeling test of the PP, PPE and PPES1 in Application Example 1, Figure 8 The middle (A) is the actual picture during the test of the sample, Figure 8 The middle (B) is the statistical diagram of the shear strength of the sample.

[0049] Figure 9 The actual picture of the PP, PPE and PPES1 coatings in Application Example 1 after 10000 times of bending Figure 9 The middle (A) and the statistical diagram of the change of the charge storage density of each coating Figure 9 The middle (B).

[0050] Figure 10 The change of the electrochemical impedance of the PP and PPES1 coatings in Application Example 1 after 3600 times of reciprocating insertion into agar simulated brain tissue.

[0051] Figure 11 The size diagram of the metal mask plate used in Application Example 2.

[0052] Figure 12 The electrochemical impedance spectrum of each sample in Application Example 2 Figure 12 The middle (A) and the average power density of each sample Figure 12Middle (B).

[0053] Figure 13 Time-frequency analysis chart of recorded electroencephalogram of each sample in application example 2.

[0054] Figure 14 MASSON section chart of each sample in application example 3 after being implanted into mice for 4 weeks Figure 14 Middle (A) and collagen thickness statistical chart (B). Figure 14 Middle (A) and collagen thickness statistical chart (B). DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. Those skilled in the art can modify or replace equivalently without departing from the spirit and scope of the present application, which should be covered within the protection scope of the present application.

[0056] The raw materials used in the following specific embodiments are all purchased from the market.

[0057] Example 1

[0058] Step 1: Put the PET substrate into the plasma machine for 5 min;

[0059] Step 2: Dissolve 0.25wt% of polyethyleneimine PEI (molecular weight ~70000), 1.25wt% of sulfobetaine methacrylate, 0.0125wt% of 3-methacryloyloxypropyltrimethoxysilane (TMSPMA), 0.0125wt% of ammonium persulfate (APS) in 10mL ethanol aqueous solution (V:V=1:1), denoted as solution component A; add 15% DMSO solution of the volume of PEDOT / PSS solution (1.1wt%) to the PEDOT / PSS solution, stir for 6h, and then dilute with ethanol aqueous solution (V:V=1:1) to a solid content of 0.32wt% as solution component B;

[0060] Step 3: Components A and B were placed in microsyringes and connected to a dual channel ultrasonic spray system. The flow rate of component A was precisely controlled by microfluidic pumps at 10, 20, 30 μL / min, while the flow rate of component B was 60 μL / min, allowing the two components to be ultrasonically atomized and thoroughly mixed at the nozzle, and then deposited on the surface of a 3 cm x 3 cm PET substrate. The spraying time was 19 minutes (component A flow rate 10 μL / min), 13 minutes (component A flow rate 20 μL / min), and 11 minutes (component A flow rate 30 μL / min), respectively. During the ultrasonic spraying process, the substrate was maintained at 65°C by a hot stage.

[0061] Step 4: After spraying, the sample was placed in a saturated humidity environment at 80°C for 2 hours, and a stable conductive coating was finally formed, and was recorded as PPES1, PPES2, and PPES3, respectively.

[0062] Example 2

[0063] Step 1: The TPU substrate was placed in a plasma machine for 5 minutes;

[0064] Step 2: 0.5 wt% PEI (molecular weight ~70000), 2.5 wt% sulfobetaine methacrylate, 0.0125 wt% 3-methacryloyloxypropyltrimethoxysilane (TMSPMA), and 0.025 wt% ammonium persulfate (APS) were dissolved in 10 mL of an ethanol aqueous solution (V:V=1:1) to form solution component A. A DMSO solution of 15% of the volume of PEDOT / PSS solution (1.1 wt%) was added to the PEDOT / PSS solution, and after stirring for 6 hours, the solution was diluted with an ethanol aqueous solution (V:V=1:1) to a solid content of 0.32 wt% to form solution component B;

[0065] Step 3: Components A and B were placed in microsyringes and connected to a dual channel ultrasonic spray system. The flow rate of component A was precisely controlled by microfluidic pumps at 40 μL / min, while the flow rate of component B was 40 μL / min, allowing the two components to be ultrasonically atomized and thoroughly mixed at the nozzle, and then deposited on the surface of a 3 cm x 3 cm TPU substrate. The spraying time was 15 minutes, and during the ultrasonic spraying process, the substrate was maintained at 65°C by a hot stage.

[0066] Step 4: After spraying, the sample was placed in a saturated humidity environment at 80°C for 2 hours, and a stable conductive coating was finally formed.

[0067] Example 3

[0068] Step 1: The PET substrate was placed in a plasma machine for 5 minutes;

[0069] Step 2: 0.25wt% of PEI (molecular weight ~25000), 1.25wt% of carboxybetaine methacrylate (CBMA), 0.026wt% of 3-methacryloxypropyltrimethoxysilane (TMSPMA), 0.025wt% of ammonium persulfate (APS) were dissolved in 10 mL of ethanol aqueous solution (V:V=1:1), noted as solution component A; 15% of DMSO solution was added into PEDOT / PSS solution (1.1wt%) and stirred for 6h, then diluted with ethanol aqueous solution (V:V=1:1) to a solid content of 0.32wt% as solution component B;

[0070] Step 3: Component A and component B were placed in microsyringes and connected to a dual-channel ultrasonic spray system. The flow rate of component A was controlled at 0 μL / min, 10 μL / min by microfluidic pump, while the flow rate of component B was 60 μL / min, so that the two components were ultrasonically atomized and fully mixed at the nozzle, and then deposited on the surface of a 3cm x 3cm PET substrate covered with a mask plate with a line width of 40 μm. The substrate was maintained at 65°C by a hot stage during the ultrasonic spraying process. The spraying time was 26 minutes (flow rate of 0 μL / min) and 19 minutes (flow rate of 10 μL / min) respectively to obtain two coatings. The substrate was maintained at 65°C by a hot stage during the ultrasonic spraying process.

[0071] Step 4: After spraying, the sample was heated at 80°C under saturated humidity for 2h to form a stable conductive coating.

[0072] Comparative Example 1

[0073] Step 1: The PET substrate was treated in a plasma machine for 5min;

[0074] Step 2: 0.25wt% of PEI (molecular weight ~25000), 1.25wt% of carboxybetaine methacrylate (CBMA), 0.026wt% of 3-methacryloxypropyltrimethoxysilane (TMSPMA), 0.025wt% of ammonium persulfate (APS) were dissolved in 10 mL of ethanol aqueous solution (V:V=1:1), noted as solution component A; 15% of DMSO solution was added into PEDOT / PSS solution (1.1wt%) and stirred for 6h, then diluted with ethanol aqueous solution (V:V=1:1) to a solid content of 0.32wt% as solution component B;

[0075] Step 3: Place component A and component B into microsyringes and connect them to a dual-channel ultrasonic spraying system. Precisely control the flow rate of component A to 0 μL / min and 10 μL / min, and the flow rate of component B to 60 μL / min using a microfluidic pump, so that the two components are ultrasonically atomized and thoroughly mixed at the nozzle, and then deposited on the surface of a 3cm × 3cm PET substrate. The spraying time is 26 minutes (component A flow rate of 0 μL / min) and 23 minutes (component A flow rate of 10 μL / min), respectively. During the ultrasonic spraying process, the substrate is maintained at 65°C by a hot stage.

[0076] Step 4: After spraying, place the sample in a saturated humidity environment and heat at 80°C for 2 hours to form a conductive coating, which is denoted as PP and PPE respectively (does not contain polymethyl methacrylate sulfobetaine (PSBMA), i.e., there is no anion-π interaction coating).

[0077] Performance testing

[0078] The thickness tests of the PP, PPE, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1 under dry and wet conditions are as follows: Figure 1 As shown, the dry thickness was measured by SEM, and the wet thickness was captured by a digital camera under a bright-field microscope at 40x magnification. The results show that the prepared coatings have similar dry thicknesses, indicating that the deposited materials are of similar quality, facilitating subsequent comparisons between coatings. After immersing the coatings in PBS solution for 24 hours, the measured wet thicknesses indicate that the PP and PPE groups exhibit more significant swelling behavior, likely due to the lack of polyelectrolyte equilibrium in the system. In contrast, the PPES1 group showed near-equilibrium charge, resulting in a decreased swelling rate. However, the swelling rates of the coatings increased with the increase of zwitterionic components in the PPES2 and PPES3 groups.

[0079] Figure 2 The values ​​represent the water contact angles of the PP, PPE, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1. The results show that the introduction of zwitterionic polymers significantly improves the hydrophilicity of the coatings.

[0080] Figure 3 The surface modulus of the PP, PPE, PPES1, and PPES3 coatings prepared in Example 1 and Comparative Example 1 is given. The modulus was measured using a nanoindenter, and the results show that the preferred PPES1 coating of this invention exhibits higher surface elasticity compared to the PP coating, which can be attributed to phase separation between the polyelectrolytes.

[0081] Figure 4The conductivity of the PP, PPES1, PPES2, and PPES3 coatings prepared in Example 1 and Comparative Example 1, Figure 4 The conductivity of each coating as a function of time of immersion in PBS solution is shown in Figure (B). The results show that, although the PP coating has a higher initial conductivity, the conductivity of the PPES1 and other modified coatings is relatively low, but the conductivity stability of the PP coating is poor, and the coating completely falls off after 28 days so that the conductivity cannot be measured. The lower initial conductivity of the PPES1 and other coatings than the PP coating can be attributed to the introduction of non-conductive components, which reduces the mass fraction of conductive components, and the de-doping of PEDOT / PSS after the addition of the polyelectrolyte PEI, which reduces the conductivity. However, in general, the PPES1 coating achieves a balance between conductivity and stability.

[0082] Figure 5 The change in charge storage density and quantitative statistics of the coatings prepared in Example 1 and Comparative Example 1 after ultrasonic treatment for 10 min, Figure 5 Figure (A) is the PP coating, Figure 5 Figure (B) is the PPE coating, Figure 5 Figure (C) is the PPES1 coating, Figure 5 Figure (D) is the PPES2 coating, Figure 5 Figure (E) is the PPES3 coating, Figure 5 Figure (F) is the quantitative statistics of each coating. The experimental procedure is as follows: the above-mentioned coatings are ultrasonically treated in a PBS water bath for 10 min, then they are cut into 2x2 cm square samples, and the cyclic voltammetry curves are measured using an electrochemical workstation, and the charge storage density is calculated to characterize the ultrasonic stability of the coatings.

[0083] As can be seen from the results, the conventional coating PP and the PPE coating without the introduction of anion-pi interaction are significantly damaged after ultrasonic treatment for 10 min, which leads to a significant decrease in the charge storage density. The PPES1, PPES2, and PPES3 coatings of the present application have significant ultrasonic stability, but considering the stability and conductivity, the PPES1 coating is used as a typical coating for subsequent testing.

[0084] Figure 6 The patterned coatings prepared according to the parameters of PPES1 in Example 1 combined with different forms of mask plates, Figure 6 Figure (A) is the pattern of the interdigital electrode coating, Figure 6 Figure (B) is the pattern of the butterfly pattern coating. It is shown that the present application can be used for the preparation of high-precision complex pattern coatings.

[0085] Evaluation of the electrochemical stability and mechanical stability of a representative PEDOT / PSS coating

[0086] In this application example, the mechanical stability and electrochemical stability of the coating prepared by the method proposed in the present application are evaluated by different methods.

[0087] 1. Coating selection

[0088] The PP, PPE control coating and PPES1 coating prepared in Comparative Example 1 and Example 1 are subjected to subsequent tests.

[0089] 2. Evaluation of electrochemical stability

[0090] The prepared coating sample is cut into a 2x2 cm square sheet as a working electrode, and then the sample is subjected to 5000 cycles of cyclic voltammetry test by a three-electrode system, a platinum mesh as a counter electrode and a silver-silver chloride electrode as a reference electrode. The electrochemical stability of the coating is determined by comparing the initial and final charge storage densities.

[0091] The results are shown in Figure 7 It can be seen that the charge storage density (CSC / CSC0) of the PP coating decreases significantly after 5000 cycles of cyclic voltammetry test. At the same time, due to the lack of anion-pi interaction, the stability of the PPE coating is improved compared with the PP coating, but the charge storage density decreases by more than 30% after 5000 cycles. The PPES1 group only decreases by about 20%, indicating that it has better electrochemical stability.

[0092] 3. Evaluation of mechanical stability

[0093] 180° peeling test is used to characterize the adhesion between PP, PPE and PPES1 coating and the substrate. The specific test procedure is as follows: high-strength adhesive tape is selected to adhere to the surface of the coating sample, ensuring that the adhesive tape and the coating are in close contact and have no bubbles; the adhered sample is fixed on the clamp of the universal material testing machine, and the tensile rate is set to 20 mm / min. The adhesive tape is subjected to a pulling force to peel off the coating along the 180° direction; the force value data during the peeling process is collected by the testing machine to quantitatively characterize the adhesion between the coating and the substrate.

[0094] Figure 8 The 180° peeling test results of PP, PPE and PPES1 in Application Example 1 are shown in Table 1. Figure 8 (A) is a physical picture of the sample during testing, Figure 8The middle (B) is a statistical chart of the shear strength of the sample. It can be seen that the shear strength of the PP coating is about 5 kPa; the shear strength of the modified PPE coating is improved to about 20 kPa; further, when the anion-pi interaction is introduced into the coating system, the adhesion ability of the PPES1 coating to the substrate is significantly enhanced, and the shear strength reaches nearly 6 times that of the traditional conductive coating. Notably, unlike the adhesion failure mode exhibited by the PP coating, the failure of the PPES1 coating is not due to insufficient adhesion between the coating and the substrate, but due to the mechanical strength of the coating itself being unable to withstand the stress during the peeling process, which belongs to the cohesive failure behavior of the coating.

[0095] To further prove that the coating preparation method proposed in the present application has a great improvement in stability compared with the traditional coating. The prepared samples PP, PPE and PPES1 were placed on a crank connecting rod device immersed in deionized water and reciprocated to repeatedly bend the samples in a wet environment. After 10,000 bends, the cyclic voltammetry curve of the coating was obtained by cyclic voltammetry test using an electrochemical workstation, and the charge storage density of the coating before and after bending was compared to determine whether the coating was damaged.

[0096] The actual objects of the PP and PPES1 coatings after 10,000 bends are shown in Figure 9 The statistical changes in charge storage density are shown in Figure 9 After 10,000 bends, the PP coating prepared by the conventional method showed obvious peeling, and its charge storage density decreased significantly. The PPE coating group also showed some damage, in contrast, the coating of the PPES1 group showed no obvious damage, and the decrease in charge storage density was limited.

[0097] In addition, the prepared PP and PPES1 coatings were repeatedly inserted into 0.6% agarose simulated brain tissue immersed in deionized water 3600 times by a crank connecting rod device, and then the electrochemical impedance spectrum of the coating was tested to confirm the damage to the coating during the insertion process. The results are shown in Figure 10 It can be seen that after 3600 cycles of insertion, the PP coating was significantly damaged, so that its electrochemical impedance could not be measured. In contrast, the electrochemical impedance of the PPES1 group did not increase significantly. The above results show that the PPES1 coating has better mechanical stability.

[0098] Application Example 2

[0099] A representative PEDOT / PSS patterned coating-prepared brain electrode was used for EEG signal monitoring and stability assessment. In this application example, the stability difference of the brain electrode prepared according to the method proposed in this invention and the electrode prepared by conventional spraying for EEG signal monitoring was evaluated.

[0100] 1. Electrode preparation and implantation

[0101] In order to fabricate brain electrodes with EEG signal recording capabilities, a customized method was developed, such as... Figure 11 The metal mask shown was used to cover the PET substrate during the spraying process. Then, EXP and CON electrodes were prepared according to the parameters for preparing PPES1 in Example 1 and PP in Comparative Example 1, respectively. The electrodes were then cut to the size suitable for implantation in the rat brain and encapsulated with silicone, exposing only the electrode contacts.

[0102] The EXP and CON electrodes were divided into two groups. One group of EXP and CON electrodes was subjected to ultrasound. Since the CON electrode could not withstand prolonged ultrasound, it was only subjected to ultrasound for 30 seconds, which was denoted as CON-SON. The EXP electrode, on the other hand, had good stability and could withstand ultrasound for 10 minutes without significant damage, which was denoted as EXP-SON.

[0103] SD rats were then anesthetized, and after exposing the skull, holes were drilled in the target area using a bone drill to implant electrodes. Two stainless steel screws were then inserted parallel to each other approximately 5 mm from the implantation site, serving as the counter electrode and reference electrode for electrochemical impedance spectroscopy, respectively. Finally, with the assistance of a stereotaxic instrument, the electrodes were precisely implanted into the predetermined brain region.

[0104] 2. Data Collection and Analysis

[0105] After electrode implantation, the electrochemical impedance of the electrodes was first measured using an electrochemical workstation (CHENHUA), with two stainless steel screws serving as the reference and counter electrodes, respectively. Subsequently, electroencephalogram (EEG) signals were acquired using an electrophysiological recording system. After signal acquisition, the EEG data underwent high-pass and low-pass filtering to generate a time-frequency plot and calculate the power spectral density.

[0106] The electrochemical impedance spectroscopy results at 1 kHz are as follows: Figure 12 As shown in (A), the untreated CON and EXP electrodes have similar impedance values. After ultrasound treatment, the impedance of the CON-SON electrode increased significantly, while the impedance of the EXP-SON electrode showed no significant change. Further analysis of the recorded EEG signals revealed, as... Figure 12 As shown in Figure (B), the quality of the signals recorded by the EXP electrode and the EXP-SON electrode before and after ultrasonic treatment is basically the same, with only a slight decrease in power density.

[0107] As Figure 13 shown, while the signal quality recorded by the CON electrode significantly decreased after ultrasonic treatment (CON-SON), the power density was greatly reduced, and the EXP electrode performed well. Based on the above results, it is shown that the brain electrode prepared by the present application has excellent electrochemical stability and signal recording performance, and can still effectively record high-quality brain electrical signals under external disturbance conditions.

[0108] Application Example 3 Representative PEDOT / PSS Coating for Improving Material Immune Compatibility and Anti-foreign Body Reaction

[0109] 1. Animal Surgical Procedure

[0110] In this application example, the fibrotic reaction of the PEDOT / PSS stable coating in a mouse subcutaneous implant model is described. The coatings PP, PPE, PPES1 prepared as in Example 1 and Comparative Example 1 were implanted in the back subcutaneously in C57BL / 6 female mice, and their fibrotic reactions were evaluated at 28 days.

[0111] 2. H&E and Masson Trichrome Staining Immunohistochemical Sections

[0112] At 4 weeks, the mice were sacrificed, the implants and their surrounding tissues were excised, fixed with 10% formaldehyde, paraffin-embedded, and sectioned for hematoxylin-eosin (H&E) / Masson trichrome staining and immunohistochemical staining. Images were acquired using a Nikon intensilight CHGFI equipped with NIS-Elements AR software and an Olympus virtual slide microscope (VS120-S6-W). Collagen density was measured by calculating the percentage of blue pixels coverage every 50 pm in the Masson trichrome-stained tissue images.

[0113] MASSON sections of each sample after 4 weeks of subcutaneous implantation in mice are shown in Figure 14 (A), and the collagen thickness statistics are shown in Figure 14 (B). From the images, it can be clearly seen that a dense collagen envelope is formed in the tissues surrounding the PET, PP, and PPE samples. Notably, almost no fibrotic reaction was observed around the PPES1 sample, indicating its excellent ability to resist foreign body reactions.

Claims

1. A method for preparing a patterned PEDOT / PSS conductive coating stable in a wet environment, characterized in that, The method comprises the following steps: Step 1: plasma or ozone activation treatment of the substrate; Step 2: dissolving the polycation, zwitterionic monomer, double-bonded silane and initiator to obtain solution component A, and diluting the PEDOT / PSS solution as solution component B; Step 3: depositing components A and B on the surface of the substrate covered with a patterned mask plate by double-channel ultrasonic atomization spraying to obtain a coating; Step 4: polymerizing the substrate with the coating under saturated humidity to obtain the patterned PEDOT / PSS conductive coating; The polycation is polyethyleneimine; The zwitterionic monomer is sulfobetaine methacrylate; The double-bonded silane is 3-methacryloyloxypropyltrimethoxysilane; In the solution component A, the mass fraction of the polycation component is 0.25% of the total solution mass, the mass fraction of the zwitterionic monomer is 1.25% of the total solution mass, the mass fraction of the double-bonded silane is 0.0125% of the total solution mass, and the mass fraction of the initiator is 0.01-0.1% of the total solution mass; In the solution component B, the mass fraction of PEDOT / PSS is 0.32wt%; In step 3, the flow rate of component A is 10 μL / min, the flow rate of component B is 60 μL / min, and the spraying time is 19 minutes; the flow rate ratio of component A to component B is 1:

6.

2. The method of claim 1, wherein the patterned PEDOT / PSS conductive coating is stable in a humid environment. The initiator comprises one or more of ammonium persulfate, potassium persulfate, azobisdimethylvaleronitrile dihydrochloride and azobisdimethylpropylamine dihydrochloride.

3. The method of claim 1, wherein the patterned PEDOT / PSS conductive coating is stable in a humid environment. The solvent of the solution component A and the solution component B comprises one or more of water and ethanol.

4. The method of claim 1, wherein the patterned PEDOT / PSS conductive coating is stable in a humid environment. In step 3, the temperature of the substrate during spraying is 50-70℃; And / or, in step 4, the polymerization is carried out under saturated humidity at 70-90℃ for 1-4h.

5. The method of claim 1, wherein the patterned PEDOT / PSS conductive coating is stable in a humid environment. The substrate comprises any one of the following materials: (1) metal material: any one of stainless steel, titanium and its alloys, cobalt-based alloy, nickel-titanium alloy, magnesium and its alloys, zinc and its alloys, iron and its alloys; or, (2) inorganic material: any one of glass, silicon dioxide, titanium dioxide, carbon material, silicon, titanium nitride; or, (3) high polymer material: any one of polyester, polyethylene, polypropylene, polytetrafluoroethylene, polyvinyl chloride, polystyrene.

6. The method of claim 1, wherein the patterned PEDOT / PSS conductive coating is stable in a humid environment. In step 1, the plasma or ozone activation time is 1-60min.

7. The wet environment-stable patterned PEDOT / PSS conductive coating prepared by the method according to any one of claims 1-6.

8. The use of the patterned PEDOT / PSS conductive coating according to claim 7 in the preparation of a bioelectrode.

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