Flexible hydrogel array electrode, its preparation method and application in flexible brain-computer interface

Abstract

The application discloses a flexible hydrogel array electrode, a preparation method thereof and application of the flexible hydrogel array electrode in a flexible brain-computer interface. The flexible hydrogel array electrode comprises a flexible low-magnetic-ratio conductive hydrogel layer and a flexible electrode array which are arranged in a stack. The conductive hydrogel layer has a porous structure, and an open conductive network structure is distributed in the conductive hydrogel layer, and the open conductive network structure is electrically connected with the flexible electrode array. The preparation method comprises a first step of preparing the flexible low-magnetic-ratio conductive hydrogel layer by a directional freezing induced phase separation technology, and a second step of preparing the flexible electrode array. The flexible hydrogel array electrode has good thermal safety, magnetic safety and biological adhesion, and can be widely applied in preparation of a flexible brain-computer interface, a flexible electronic device, an intelligent protection system or a wearable neural interface platform.

Description

Technical Field

[0001] The present invention belongs to the fields of flexible electronics, neural engineering and biosensor technology, and specifically relates to a flexible hydrogel array electrode, a preparation method thereof and an application in a flexible brain-computer interface. Background Art

[0002] In recent years, brain-computer interface (BCI) technology has been widely used in areas such as neurological function monitoring, disease intervention, and intelligent control. Traditional EEG acquisition electrode systems suffer from significant magnetic artifacts, radiofrequency-induced heating, and signal distortion in the high-magnetic field of magnetic resonance imaging (MRI), making it difficult to achieve simultaneous acquisition and fusion analysis of EEG and MRI images.

[0003] One existing solution is to use carbon-based flexible electrodes. A typical carbon-based flexible electrode can be prepared using the following process: multi-walled or single-walled carbon nanotubes (CNTs) are selected and surface functionalized. The functionalized CNTs are then added to a solvent (such as N,N-dimethylformamide (DMF) or dichloromethane) and uniformly dispersed using ultrasonic treatment to obtain a stable CNT dispersion. Polyurethane prepolymer or polyurethane (PU) particles are then added to the CNT dispersion and heated and stirred to fully dissolve in the solvent and mix with the CNTs, forming a uniform CNT / PU composite solution. The composite solution is then evenly coated onto a flat substrate (such as a glass plate or polytetrafluoroethylene (PTFE) membrane) and gradually heated at room temperature or in a vacuum oven to evaporate the solvent and form a film (typically at 50–80°C), thereby preparing a flexible composite electrode (referred to as a CNT / PU composite electrode). However, the impedance of such electrodes is typically higher than 10 kΩ at a frequency of 1 kHz, making them difficult to meet the low impedance requirements for high-quality neural signal acquisition, limiting their application in high-signal-to-noise ratio EEG monitoring. At the same time, these electrodes are generally only suitable for single-signal acquisition, making them unsuitable for building multimodal brain-computer interface systems. Furthermore, due to the uneven conductive network structure of the composite system, these electrodes are prone to high interfacial resistance and signal attenuation, resulting in insufficient stability and reusability.

[0004] In order to achieve multimodal neural signal capture with high temporal and spatial resolution, the field urgently needs to develop new flexible electrode systems with MRI compatibility, high conductivity, and biocompliance to break down the barriers between structural imaging and dynamic neural signals. Summary of the Invention

[0005] The main purpose of the present invention is to provide a flexible hydrogel array electrode, a preparation method thereof and an application in a flexible brain-computer interface to overcome the shortcomings of the existing technology.

[0006] In order to achieve the aforementioned object of the invention, the present invention adopts the following technical solutions.

[0007] A first aspect of the present invention provides a flexible hydrogel array electrode, which comprises a stacked flexible low magnetic susceptibility conductive hydrogel layer and a flexible electrode array;

[0008] The conductive hydrogel layer comprises a paramagnetic material and a diamagnetic material, wherein the conductive substance in the diamagnetic material is used to form an ion conductive network, and the non-conductive substance in the diamagnetic material is used to form a hydrogel matrix, and the paramagnetic material is dispersed in the hydrogel matrix;

[0009] At the same time, the conductive hydrogel layer has a porous structure, and more than 70% of the holes in the porous structure are oriented along the thickness direction of the hydrogel layer;

[0010] In addition, an open conductive network structure is distributed in the conductive hydrogel layer, and the open conductive network structure includes an interpenetrating structure of an electronic conductive network and an ion conductive network. The electronic conductive network includes a continuous three-dimensional conductive network structure formed by interconnecting the paramagnetic materials, and the ion conductive network includes a continuous conductive path formed by the hydrogel matrix, and the open conductive network structure is electrically connected to the flexible electrode array.

[0011] The second aspect of the present invention provides a method for preparing the flexible hydrogel array electrode, which comprises a first step of preparing a flexible low magnetic susceptibility conductive hydrogel layer by a directional freezing-induced phase separation technique and a second step of preparing a flexible electrode array;

[0012] The first step includes: performing directionally freezing with a first precursor liquid at a first temperature to form a first precursor structure layer, and performing directionally freezing with a second precursor liquid at a second temperature to form a second precursor structure layer, and the first precursor structure layer and the second precursor structure layer are stacked;

[0013] performing freeze-drying or thawing-cross-linking treatment on the first precursor structure layer and the second precursor structure layer to form a hydrogel precursor layer;

[0014] Processing an open conductive network structure in the hydrogel precursor layer to form the conductive hydrogel layer;

[0015] The first precursor liquid and the second precursor liquid both contain paramagnetic material, diamagnetic material and solvent, and the concentration of paramagnetic material in the first precursor liquid is greater than the concentration of paramagnetic material in the second precursor liquid, the concentration of diamagnetic material in the first precursor liquid is greater than the concentration of diamagnetic material in the second precursor liquid, and the first temperature is lower than the second temperature.

[0016] The third aspect of the present invention provides the use of the flexible hydrogel array electrode in preparing flexible electronic devices, intelligent protection systems or wearable neural interface platforms.

[0017] The fourth aspect of the present invention provides the use of the flexible hydrogel array electrode in preparing a flexible brain-computer interface.

[0018] A fifth aspect of the present invention provides a magnetic-electric dual-mode neural signal monitoring and regulation system, which includes the flexible hydrogel array electrode.

[0019] A sixth aspect of the present invention further provides a multimodal signal acquisition and fusion method, comprising:

[0020] Providing the flexible hydrogel array electrode;

[0021] Attaching the flexible hydrogel array electrode to the surface of the subject's skin, and making the flexible electrode array therein contact with the subject's skin;

[0022] Examining a subject with a magnetic resonance device, and simultaneously collecting biological signals of the subject in a magnetic resonance environment using at least the flexible hydrogel array electrode, wherein the biological signals include one or more of brain nerve signals, electrocardiogram signals, and electromyography signals;

[0023] The collected magnetic resonance signal is fused with the biological signal.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The flexible low magnetic susceptibility conductive hydrogel layer provided by the present invention has low magnetic susceptibility, high conductivity and good flexibility. It adopts an innovative gradient modulus metamaterial structure design and has a dual gradient modulus structure. By regulating the network density and skeleton wall thickness ratio of the first structural layer (high modulus layer) and the second structural layer (low modulus layer), programmable adjustment of the mechanical response is achieved, breaking through the bottleneck of the uncontrollable mechanical properties of traditional structural hydrogels; through the regulation of microstructure parameters, it exhibits excellent energy absorption capacity and structural stability under compression and shear conditions, has high deformability and compressibility, and can be widely used in the preparation of flexible brain-computer interfaces, flexible electronics, intelligent protection systems and wearable neural interface platforms.

[0026] (2) The open conductive network structure provided by the present invention is constructed by template sacrificial, photolithographic or induced phase separation technology to regulate the channel spacing and conductive coupling density, forming a three-dimensional ion-electron cooperative channel, thereby reducing the radio frequency (RF) heating effect and magnetic artifacts in a high magnetic field environment.

[0027] (3) The flexible electrode array provided by the application enhances mechanical stability and tissue adhesion through the synergistic design of a high modulus substrate and a low modulus hydrogel layer, ensuring stable signal transmission.

[0028] (4) The flexible hydrogel array electrode provided by the application has good thermal safety, magnetic safety and biological adhesion, improving the applicability of the flexible brain-computer interface system in complex application scenarios such as precise rehabilitation, auxiliary control and intraoperative navigation.

[0029] (5) The magnetic-electric dual-mode neural signal monitoring and regulation system provided by the application realizes stable and accurate acquisition of biological signals in a high magnetic field MRI environment, significantly improving the spatial resolution and time accuracy of signal acquisition.

[0030] (6) The multi-modal signal acquisition and fusion method provided by the application can stably operate in a 1.5T and above magnetic resonance environment, realizing high-fidelity acquisition of brain neural signals and multi-modal fusion of magnetic resonance images. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0032] Figure 1 is a schematic diagram of the overall structure of a flexible hydrogel array electrode in an embodiment of the application;

[0033] Figure 2 is a plan view of a flexible hydrogel array electrode in an embodiment of the application;

[0034] Figure 3 is a schematic diagram of an application scenario of a flexible hydrogel array electrode in an embodiment of the application;

[0035] Figure 4 is an optical diagram of a cross electrode pattern of the flexible hydrogel array electrode of embodiment 1 of the application;

[0036] Figure 5 is a schematic diagram of the porous microstructure of the high modulus layer in the flexible hydrogel array electrode of embodiment 1 of the application;

[0037] Figure 6 is a scanning electron microscope image of the high modulus layer in the flexible hydrogel array electrode of embodiment 1 of the application at 100 μm;

[0038] Figure 7is a scanning electron microscope image of the high modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention at 10 μm;

[0039] Figure 8 This is a finite element mechanical simulation diagram of the stress on the high modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention;

[0040] Figure 9 This is a finite element mechanics simulation diagram of the stress distribution of the high modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention;

[0041] Figure 10 Schematic diagram of the porous microstructure of the low modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention;

[0042] Figure 11 is a scanning electron microscope image of the low modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention at a depth of 1 mm;

[0043] Figure 12 is a scanning electron microscope image of the low modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention at 200 μm;

[0044] Figure 13 : is a finite element mechanical simulation diagram of the stress on the low modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention;

[0045] Figure 14 This is a finite element mechanical simulation diagram of the stress distribution of the low modulus layer in the flexible hydrogel array electrode of Example 1 of the present invention;

[0046] Figure 15 is an optical image of a cross electrode pattern of the flexible hydrogel array electrode according to Example 2 of the present invention;

[0047] Figure 16 is an optical image of a cross electrode pattern of the flexible hydrogel array electrode of Example 9 of the present invention;

[0048] Figure 17 Graphs showing the surface potential performance of the flexible hydrogel array electrode component materials and their hydrogel electrode arrays according to Example 1 and Comparative Example 1 of the present invention;

[0049] Figure 18 This is a full-range hysteresis loop test diagram comparing the flexible hydrogel array electrode composition materials and hydrogel electrode arrays of Example 1 and Comparative Example 1 of the present invention with metallic iron;

[0050] Figure 19 1. This is a full-range hysteresis loop test diagram of the flexible hydrogel array electrode composition material and the hydrogel electrode array of Example 1 and Comparative Example 1 of the present invention;

[0051] Figure 20 1. Magnetic hysteresis loop test diagram of the flexible hydrogel array electrode component material and its hydrogel electrode array in Example 1 and Comparative Example 1 of the present invention and metallic iron in the positive range;

[0052] Figure 21 1 is a test diagram of the positive range magnetic hysteresis loop of the flexible hydrogel array electrode component material and the hydrogel electrode array of Example 1 and Comparative Example 1 of the present invention;

[0053] Figure 22 is a compressive stress-strain curve of the flexible hydrogel array electrode of Example 1 of the present invention;

[0054] Figure 23 is a compressive stress relaxation test curve of the flexible hydrogel array electrode of Example 1 of the present invention;

[0055] Figure 24 is a cyclic compression stress-time response curve of the flexible hydrogel array electrode of Example 1 of the present invention;

[0056] Figure 25 is a cyclic compression stress-strain response curve of the flexible hydrogel array electrode of Example 1 of the present invention;

[0057] Figure 26 is a cyclic compression stress-time response curve of the flexible hydrogel array electrode of Comparative Example 1 of the present invention;

[0058] Figure 27 is a cyclic compression stress-strain response curve of the flexible hydrogel array electrode of Comparative Example 1 of the present invention;

[0059] Figure 28 1 is a graph showing the storage modulus and loss modulus of the flexible hydrogel array electrode according to Example 1 of the present invention and Comparative Example 1 as a function of frequency;

[0060] Figure 29 1 is a graph showing the viscosity of the flexible hydrogel array electrode according to Example 1 of the present invention and Comparative Example 1 as a function of frequency;

[0061] Figure 30 1 is a graph showing the small-angle X-ray diffraction test results of the flexible hydrogel array electrode of Example 1 of the present invention and Comparative Example 1;

[0062] Figure 31 1 is a comparison diagram of the impedance spectra of the flexible hydrogel array electrodes of Example 1 of the present invention and Comparative Example 1;

[0063] Figure 32 1 is a graph showing the conductivity of the flexible hydrogel array electrode according to Example 1 of the present invention and Comparative Example 1 as a function of frequency;

[0064] Figure 33CV test curves of the flexible hydrogel array electrodes of Example 1 of the present invention and Comparative Example 1;

[0065] Figure 34 100 cycles of the CV test curve of the flexible hydrogel array electrode of Example 1 of the present invention;

[0066] Figure 35 This is a cell activity graph of the flexible hydrogel array electrode of Example 1 of the present invention on the first day;

[0067] Figure 36 This is a cell activity graph of the flexible hydrogel array electrode of Example 1 of the present invention on the second day;

[0068] Figure 37 This is a cell activity graph of the flexible hydrogel array electrode of Example 1 of the present invention on the third day;

[0069] Figure 38 is a cytological biocompatibility diagram of the flexible hydrogel array electrode of Example 1 of the present invention;

[0070] Figure 39 This is a waveform diagram of actual EEG signals of the flexible hydrogel array electrode according to Example 1 of the present invention. DETAILED DESCRIPTION

[0071] In view of the above-mentioned problems existing in the prior art, after extensive and in-depth research, the inventors of the present invention provide a flexible hydrogel array electrode, a preparation method thereof, and an application in a flexible brain-computer interface.

[0072] The technical solution, its implementation process and principles are further explained below.

[0073] As one aspect of the technical solution of the present invention, a flexible hydrogel array electrode is provided, comprising a stacked flexible low magnetic susceptibility conductive hydrogel layer and a flexible electrode array;

[0074] The conductive hydrogel layer comprises a paramagnetic material and a diamagnetic material, wherein the conductive substance in the diamagnetic material is used to form an ion conductive network, and the non-conductive substance in the diamagnetic material is used to form a hydrogel matrix, and the paramagnetic material is dispersed in the hydrogel matrix;

[0075] At the same time, the conductive hydrogel layer has a porous structure, and more than 70% of the holes in the porous structure are oriented along the thickness direction of the hydrogel layer;

[0076] In addition, an open conductive network structure is distributed in the conductive hydrogel layer, and the open conductive network structure includes an interpenetrating structure of an electronic conductive network and an ion conductive network. The electronic conductive network includes a continuous three-dimensional conductive network structure formed by interconnecting the paramagnetic materials, and the ion conductive network includes a continuous conductive path formed by the hydrogel matrix, and the open conductive network structure is electrically connected to the flexible electrode array.

[0077] In the present invention, the paramagnetic material refers to a conductive component with a positive magnetic susceptibility (χ>0) in an external magnetic field, the diamagnetic material refers to a structural support material with a negative magnetic susceptibility (χ<0) or near-zero magnetic response, and the open conductive network structure refers to a three-dimensional porous conductive path network connected in the gel by template sacrifice or etching, while forming interpenetration of electronic and ionic conductive paths, which ensures both charge transfer and ion diffusion capacity, and helps to reduce interface impedance and enhance signal response capability.

[0078] In the present invention, the pore orientation arrangement of more than 70% of the porous structure of the conductive hydrogel layer has the following advantages: (1) Through the gradient composite design of paramagnetic materials and diamagnetic materials, the overall magnetic susceptibility of the electrode is significantly reduced, which is more consistent with the magnetic susceptibility of brain tissue, reducing magnetic artifacts and signal interference in strong magnetic field imaging such as MRI / MEG (magnetoencephalography), and achieving high magnetic resonance compatibility of the electrode; (2) The three-dimensional electronic network structure in the open conductive network provides an efficient electron transmission path, and the continuous ion pathway enhances the overall conductivity of the hydrogel, so that the electrode exhibits a higher signal-to-noise ratio and signal fidelity in high-density EEG acquisition; (3) The porous structure, especially the pores arranged along the directional gradient, makes the hydrogel layer form a soft-hard dual-mode layer structure, which better fits the skin or brain tissue, reduces motion artifacts, improves acquisition stability, and enhances mechanical flexibility and fit stability; (4) Improves resistance to thermal distortion and RF safety. The pore orientation structure optimizes the heat flow conduction path, helps to quickly dissipate heat, suppresses radiofrequency-induced heating, and improves thermal safety under MRI conditions.

[0079] In the present invention, the increasing content of paramagnetic-diamagnetic material with depth facilitates layer-by-layer shielding of magnetic interference and forms a "magnetic gradient buffer layer," which can reduce localized induced distortion caused by sudden changes in field strength. Furthermore, the porous structure arranged along the direction imparts anisotropic mechanical behavior and thermo-electric coupling to the hydrogel, improving compliance and conductive stability. Furthermore, within the conductive network structure, ion channels provide stable ion migration pathways, while the electronic network establishes a rapid electron transmission path. The two are coupled to form a high-throughput, low-impedance composite conductive structure.

[0080] If the pores are not oriented, the following negative effects will occur: (1) Deterioration of mechanical properties: disordered arrangement of pores will lead to uneven stress distribution of the hydrogel, which is prone to local stress concentration, tearing or inconsistent deformation during stretching and compression, and reduced fit; (2) Decreased signal stability: The non-oriented structure destroys the continuity and directional transmission advantages of the conductive network, which may lead to resistance fluctuations, local loss of conductive paths, increased signal noise, and reduced acquisition accuracy; (3) Decreased thermal management performance: The disordered porous structure will form a thermal resistance barrier, inhibiting the effective conduction of heat to the surface, which may cause local heat accumulation and the formation of hot spots in MRI, increasing safety risks.

[0081] In some embodiments, the conductive hydrogel layer further comprises a first structural layer and a second structural layer; the first structural layer is stacked on the second structural layer and has a directional microporous structure; the second structural layer has a large-pore flexible network structure; the flexible electrode array is stacked on the first structural layer;

[0082] Among them, the Young's modulus of the first structural layer is greater than the Young's modulus of the second structural layer, the content of paramagnetic material in the first structural layer is greater than the content of paramagnetic material in the second structural layer, the content of diamagnetic material in the first structural layer is greater than the content of diamagnetic material in the second structural layer, and the average pore size of the holes contained in the large-pore flexible network structure is greater than the average pore size of the holes contained in the oriented microporous structure.

[0083] Furthermore, the second structural layer is located at the bottom of the conductive hydrogel layer.

[0084] The first structural layer and the second structural layer may also be named as a high modulus layer and a low modulus layer, respectively.

[0085] In the present invention, the conductive hydrogel layer has at least the following effects by adopting the above-mentioned structural design: (1) improving magnetic resonance compatibility and reducing imaging artifacts. The first structural layer (close to the flexible electrode array) contains more paramagnetic materials, whose relatively high magnetic susceptibility helps to enhance the electronic conductive network and effectively conduct neural electrical signals; the second structural layer (far away from the electrode array) contains diamagnetic materials, whose low magnetic susceptibility is more compatible with brain tissue, effectively shielding magnetic induction disturbances, reducing MRI imaging artifacts and electromagnetic noise; the gradient transition of paramagnetic-diamagnetic materials from bottom to top forms a magnetic susceptibility buffer layer, which can avoid mutation-induced signal distortion or hot spot generation in strong magnetic fields such as MRI / MEG. (2) Improving interface conformity and wearing comfort. The first structural layer has a high modulus and can provide structural support and device stability; the second structural layer has a low modulus and has good softness and skin / brain tissue conformity, which can achieve dynamic contact stability and uniform pressure distribution; the double-layer structure constructs a "soft and hard dual-mimic interface" similar to that of a biomimetic, reducing motion artifacts and enhancing signal acquisition stability. (3) Construct anisotropic conductive / heat transfer pathways to improve signal quality and thermal safety. The combination of gradient-distributed magnetic materials and porous structures allows ion / electron transfer pathways to form directional preferential channels in the thickness direction, which is beneficial for improving conductive efficiency and signal-to-noise ratio. At the same time, the gradient structure's thermal conductivity transitions layer by layer, facilitating rapid heat diffusion and discharge in the vertical direction, reducing local temperature rise caused by inductance or RF excitation in the MRI environment and ensuring safety in use.

[0086] Furthermore, the Young's modulus of the first structural layer is 0.5-2 MPa, the diamagnetic material content is 5-15 wt%, the paramagnetic material content is 2-5 wt%, and the pore diameter of the pores contained in the oriented microporous structure is 20-50 μm.

[0087] Furthermore, the thickness of the first structural layer is 0.1-2 mm.

[0088] Furthermore, the Young's modulus of the second structural layer is 0.05~0.35 MPa, the diamagnetic material content is 1~5 wt%, the paramagnetic material content is 0.1~1 wt%, and the pore size of the pores contained in the large-pore flexible network structure is 50~150 μm.

[0089] Furthermore, the thickness of the second structural layer is 0.1-1 mm.

[0090] Furthermore, the second structural layer and the first structural layer are formed as one body.

[0091] Furthermore, the diameter of the ion channel formed in the first structural layer is 1-50 μm, and the diameter of the ion channel formed in the second structural layer is 50-300 μm.

[0092] In this invention, the gradient matching of mechanical properties improves interface stability and comfort. Specifically, the first structural layer has a high Young's modulus (0.5-2 MPa), which enhances support for the electrode array, ensuring the integrity of the array structure and stable signal connection. The second structural layer has a low Young's modulus (0.05-0.35 MPa), which softly conforms to brain / skin tissue and avoids stress concentration. By constructing a soft-hard gradient transition interface, motion interference is alleviated, artifacts are reduced, and long-term wear comfort and signal stability are improved.

[0093] Furthermore, magnetic susceptibility gradient control improves magnetic compatibility. Specifically, the first structural layer has a high content of diamagnetic material (5-15%) and a moderate amount of paramagnetic material (2-5%), balancing conductivity and magnetic response control. The second structural layer is primarily diamagnetic material (1-5%), with minimal paramagnetic material (≤1%), minimizing the overall magnetic susceptibility. By forming a paramagnetic to diamagnetic transition region, the magnetic boundary mutation point is eliminated, effectively reducing magnetic artifacts and RF thermal effects in MRI / MEG.

[0094] Secondly, the micropore size gradient and orientation optimize signal conduction and heat / water flux. Specifically, the small pore size (20-50 μm) in the first structural layer limits ion leakage, improving charge density control and signal resolution. The large pore size (50-150 μm) in the second structural layer facilitates liquid / heat exchange, enhancing breathability and heat dissipation efficiency. The micropore size gradient and orientation meet the requirements of "stable conduction" in the inner layer and "heat dissipation and drainage" in the outer layer, improving overall physiological compatibility.

[0095] Finally, the ion channel size gradient balances electrical conductivity and structural integrity. The ion channel diameter in the first structural layer ranges from 1 to 50 μm, facilitating high-density, multi-point, and precise signal acquisition. The channel diameter in the second structural layer ranges from 50 to 300 μm, facilitating sustained ion release, water molecule exchange, and reduced impedance. This ion channel size gradient design achieves high-throughput signal transmission and directional control, enhancing the acquisition efficiency of weak signals such as EEG. If the channel is too small (<1 μm), ion migration will be impeded, resulting in reduced conductivity, unstable signals, and sluggish response. If the channel is too large (>300 μm), there will be no directional constraints and stress concentration, leading to structural fragility and easy collapse, signal dispersion, and increased artifacts. Excessively large channels in the first structural layer can compromise the microelectrode's ability to accurately capture data, resulting in reduced accuracy and increased crosstalk. If the channels in the second structural layer are too small, thermal conductivity and heat dissipation efficiency will be reduced, affecting heat accumulation and posing a risk of burns under RF conditions.

[0096] In some embodiments, the conductive hydrogel layer has pores, the pores are interconnected, the porosity is 60-90%, and the overall connectivity of the pores is greater than 70%.

[0097] In some embodiments, the pore channel spacing in the open conductive network structure is 20-200 μm, and the conductive coupling density is 0.1-0.8.

[0098] In some embodiments, the Young's modulus of the conductive hydrogel layer increases in a direction approaching the flexible electrode array.

[0099] In some embodiments, the flexible electrode array includes a plurality of conductive pattern structures arranged in an array.

[0100] Furthermore, the length and width of the conductive pattern structure are 1-20 mm, and the spacing between adjacent conductive pattern structures is 20-200 μm.

[0101] Furthermore, the shape of the conductive pattern structure includes but is not limited to a cross or a circle. If it is a cross, the line width of the conductive pattern structure is 5-50 μm.

[0102] In some embodiments, the flexible electrode array corresponds to 32 to 256 signal acquisition channels.

[0103] In some embodiments, the paramagnetic material includes, but is not limited to, a combination of one or more of MXene, silver nanowires, carbon nanotubes, or titanium nanosheets.

[0104] In some embodiments, the diamagnetic material includes a non-conductive substance and a conductive substance. The non-conductive substance includes, but is not limited to, a polymer, including, but is not limited to, a combination of one or more of polyvinyl alcohol, chitosan, or polyethylene glycol. The conductive substance includes, but is not limited to, a conductive agent, including, but is not limited to, a combination of one or more of a conductive polymer, graphene, or a metal salt. The conductive polymer includes, but is not limited to, PEDOT:PSS. The metal salt includes, but is not limited to, at least one of zirconium sulfate, calcium chloride, and ferric chloride.

[0105] Figure 1-Figure 2 A flexible hydrogel array electrode according to one embodiment of the present invention is shown. The electrode comprises a conductive hydrogel layer 1 and a flexible electrode array 2 stacked on the conductive hydrogel layer. The conductive hydrogel layer 1 includes a first structural layer 11 and a second structural layer 12, arranged sequentially in a direction away from the flexible electrode array 2. To ensure and enhance the electrical connection between the flexible electrode array 2 and the conductive hydrogel layer 1, an electrode interface cable 3 may also be provided on the conductive hydrogel layer 1. The flexible electrode array 2 may include multiple conductive pattern structures arranged in an array, such as a cross-shaped conductive pattern structure 21, which may be made of a metal such as gold.

[0106] As an aspect of the technical solution of the present application, the method for manufacturing the flexible hydrogel array electrode comprises a first step of manufacturing a flexible low-magnetic-conductivity conductive hydrogel layer by directional freezing induced phase separation technology and a second step of manufacturing a flexible electrode array.

[0107] The first step comprises directional freezing of a first precursor liquid at a first temperature to form a first precursor structure layer and directional freezing of a second precursor liquid at a second temperature to form a second precursor structure layer, and the first precursor structure layer and the second precursor structure layer are stacked.

[0108] The first precursor structure layer and the second precursor structure layer are subjected to freeze-drying or thawing-crosslinking treatment, thereby forming a hydrogel precursor layer.

[0109] An open conductive network structure is processed in the hydrogel precursor layer, thereby forming the conductive hydrogel layer.

[0110] The first precursor liquid and the second precursor liquid both comprise paramagnetic material, diamagnetic material and solvent, and the concentration of the paramagnetic material in the first precursor liquid is greater than that in the second precursor liquid, and the concentration of the diamagnetic material in the first precursor liquid is greater than that in the second precursor liquid, and the first temperature is lower than the second temperature.

[0111] In some embodiments, the first precursor liquid comprises 2-5 wt% MXene and / or 2-5 wt% carbon nanotube, and 0.1-1.5 wt% PEDOT:PSS, 10-15 wt% polyvinyl alcohol and / or 2-5 wt% polyethylene glycol, 1-5 wt% chitosan, 0.5-1 wt% metal salt, or a combination of one or more thereof.

[0112] In some embodiments, the second precursor liquid comprises 1-2 wt% MXene and / or 0.5-1 wt% carbon nanotube, and 0.1-1 wt% PEDOT:PSS, 5-8 wt% polyvinyl alcohol and / or 1-2 wt% polyethylene glycol, 0.5-2.5 wt% chitosan, 0.5-1 wt% metal salt, or a combination of one or more thereof.

[0113] The metal salt comprises at least any one of zirconium sulfate, calcium chloride and iron chloride, but is not limited thereto.

[0114] In some cases, the first precursor liquid and the second precursor liquid in the present application can also be respectively named as high-modulus upper-layer precursor liquid and low-modulus lower-layer precursor liquid.

[0115] In some embodiments, the directional freezing is performed under a one-way temperature gradient condition.

[0116] In some embodiments, the first temperature is -40°C to -80°C, and the second temperature is -10°C to -40°C.

[0117] In some embodiments, the first precursor solution is directionally frozen at the first temperature for 6 to 12 hours, and the second precursor solution is directionally frozen at the second temperature for 3 to 6 hours.

[0118] In the present invention, the conductive hydrogel layer has a double-layer gradient modulus structure. The first precursor liquid is frozen at a relatively low temperature to form a denser and more crystallized network structure, and the corresponding hydrogel modulus is higher; the second precursor liquid is frozen at a relatively high temperature to form a loose porous structure with a lower modulus; the formed "hard bottom and soft top" or "hard inside and soft outside" double structure helps to maintain the structural stability of the internal support electrode array, and the outer layer fits the skin / brain tissue and relieves mechanical stress concentration, forming a stress gradient matching interface as a whole to reduce shedding and motion artifacts.

[0119] Moreover, the first precursor liquid has a higher content of paramagnetic and diamagnetic materials, which can enhance conductivity and adjust magnetic response; the second precursor liquid has a lower content, which makes the magnetic susceptibility of the overall structure gradually decrease along the thickness direction; the gradient magnetic susceptibility design can effectively eliminate the magnetic interface mutation points, reduce MRI / MEG imaging artifacts and the risk of induction heating, and enhance structural stability and imaging compatibility in a magnetic field environment.

[0120] In addition, the in-situ stacking and freezing of the first precursor structure layer and the second precursor structure layer, and cross-linking through freeze-drying or thawing, also have synergistic effects, such as: achieving seamless bonding and conformal integration between materials; avoiding interlayer delamination and mechanical damage; and improving the overall stability and service life of the multilayer structure.

[0121] In the present invention, a flexible low magnetic susceptibility conductive hydrogel layer is prepared using a unidirectional freezing technique, which has at least the following functions: (1) constructing an oriented microporous structure. Unidirectional freezing causes ice crystals to grow in a selected direction, thereby forming microporous channels that are uniformly arranged and penetrate the depth after thawing or drying; the crystals act as a "template" to guide the directional arrangement of polymer chains in the hydrogel, providing a directional channel for subsequent ion / electron conduction. (2) realizing a functional gradient layer. By controlling the freezing direction and speed, pore size gradients, modulus gradients, and component gradients (such as magnetic susceptibility and conductivity) along the thickness direction can be achieved; this helps to create a structure with a soft outer layer and a hard inner layer, achieving a balance between skin adhesion and internal mechanical support. (3) enhancing interface stability and integration. Combined with a double-layer gradient structure, unidirectional freezing can form a continuously transitioning microstructure interface, improve interlayer fusion, and avoid peeling and fracture.

[0122] On the contrary, if the unidirectional freezing technology is not adopted, it may lead to disordered micropores, random structure, discontinuous ion / electron conduction paths; it is impossible to form an effective modulus gradient and functional transition zone, resulting in easy interface detachment and stress concentration; local high magnetic susceptibility materials are prone to magnetic artifacts, and heat is not easy to dissipate; the overall structural mechanical properties are reduced, and the flexible adhesion and electrical signal stability are limited.

[0123] In some embodiments, the solvent includes but is not limited to water.

[0124] In some embodiments, the open conductive network structure is processed in the hydrogel precursor layer at least by microetching or template sacrificial means.

[0125] In some embodiments, the second step includes: preparing the flexible electrode array by at least laser etching or microelectronic printing.

[0126] In some embodiments, both the first precursor liquid and the second precursor liquid contain a sacrificial template, and the sacrificial template is distributed in both the first precursor structure layer and the second precursor structure layer; wherein the mass fraction of the sacrificial template in the first precursor liquid is 1~2 wt%, and the mass fraction of the sacrificial template in the second precursor liquid is 2~5wt%.

[0127] Furthermore, the sacrificial template includes but is not limited to calcium alginate microspheres or gelatin microspheres.

[0128] The preparation method specifically includes: removing at least a portion of the sacrificial template in the hydrogel precursor layer, thereby processing the open conductive network structure in the hydrogel precursor layer.

[0129] As one aspect of the technical solution of the present invention, it provides the use of the flexible hydrogel array electrode in preparing flexible electronic devices, intelligent protection systems or wearable neural interface platforms.

[0130] As one aspect of the technical solution of the present invention, the present invention provides the use of the flexible hydrogel array electrode in preparing a flexible brain-computer interface.

[0131] As one aspect of the technical solution of the present invention, a magnetic-electric dual-mode neural signal monitoring and regulation system is provided, including the flexible hydrogel array electrode.

[0132] As one aspect of the technical solution of the present invention, it also provides a multimodal signal acquisition and fusion method including:

[0133] Providing the flexible hydrogel array electrode;

[0134] attaching the flexible hydrogel array electrode on the skin surface of the subject and making the flexible electrode array in the flexible hydrogel array electrode contact the skin of the subject;

[0135] performing examination on the subject with a magnetic resonance device, and collecting biological signals of the subject in the magnetic resonance environment at least with the flexible hydrogel array electrode, the biological signals including one or more of brain neural signals, electrocardio signals and electromyography signals;

[0136] fusing the collected magnetic resonance signals and the biological signals.

[0137] In some embodiments, the multi-modal signal collection and fusion method specifically includes: attaching the flexible hydrogel array electrode on the skin surface of the head of the subject and collecting brain neural signals of the subject in the magnetic resonance environment.

[0138] Further, the magnetic field strength of the magnetic resonance environment is above 1.5T. Figure 3 That is, a typical application scenario of a flexible hydrogel array electrode in an embodiment of the present application is shown, the flexible hydrogel array electrode includes a conductive hydrogel layer 1 and a flexible electrode array 2, the flexible hydrogel array electrode is attached on the skin surface of the head of the subject and makes the flexible electrode array 2 in the flexible hydrogel array electrode contact the skin of the subject.

[0139] It needs to be noted that the multi-modal signal collection and fusion method provided by the present application is for non-diagnosis and treatment purposes, and the obtained neural signals of the subject are only intermediate results and cannot be used for directly judging the health status of the human body or for disease diagnosis and treatment.

[0140] The multi-modal signal collection and fusion method constructed by the present application can break through the barrier between the time dimension and the space dimension, realize the capture and analysis of the neural activity in the EEG-MRI structure-function-dynamic three-dimensional dimensions, and provide data support for the research on the multi-region collaborative activity of the brain in different states such as cognition, movement and emotion, and is expected to promote the evolution of the brain function network atlas from “structural connection” to “functional connection + dynamic prediction”.

[0141] In summary, the low-magnetic-ratio conductive hydrogel layer in the flexible hydrogel array electrode provided by the present application adopts different proportions of paramagnetic materials and diamagnetic materials to form a double-gradient modulus structure; paramagnetic-diamagnetic composite conductive fillers are embedded in the inside, and an electronic conductive network and an ionic conductive network interpenetrating structure is constructed through directional freezing induced phase separation and template sacrifice technology, which effectively reduces the magnetic artifact and thermal effect. The multi-modal signal collection and fusion method has good magnetic safety, thermal safety and biocompatibility under the condition of 1.5T and above magnetic resonance, and is suitable for brain function research, intraoperative navigation and various scenes.

[0142] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention.

[0143] Where specific experimental procedures or conditions are not specified in the examples, the experiments were carried out according to conventional experimental procedures or conditions described in literature in the field. Reagents or instruments used without manufacturer specified are commercially available. Commercially available options for other raw materials and instruments not mentioned are conventional and do not relate to the core technical means of the present invention.

[0144] The sources of some raw materials in the examples and comparative examples of the present invention are as follows:

[0145] Polyvinyl alcohol (PVA, Mw≈89000), chitosan (CS, deacetylation degree >85%, molecular weight approximately 2000~4000), polyethylene glycol (molecular weight approximately 10000), MXene (thickness approximately 10μm, diameter approximately 100nm), zirconium sulfate (particle size approximately 10~100nm), calcium alginate microspheres (particle size approximately 0.01~0.1mm), carbon nanotubes (average length approximately 10μm, average diameter approximately 20nm), silver nanowires (average length approximately 10μm, average diameter approximately 20nm), titanium nanosheets (average thickness approximately 10μm, average diameter approximately 100nm), gelatin microspheres (particle size approximately 0.01~0.1mm).

[0146] Example 1

[0147] This example provides a flexible hydrogel array electrode optimized by doping with high-valent diamagnetic ions (zirconium sulfate). The electrode exhibits low magnetic susceptibility, high conductivity, a modulus gradient, a controllable microporous structure, and magneto-electric bimodal compatibility. This example also demonstrates its excellent structural, mechanical, and conductive properties through multiple characterizations and simulations. The details are as follows:

[0148] (1) Material ratio:

[0149] The high modulus upper layer precursor solution (i.e., the first precursor solution) contains the following components: approximately 15 wt% polyvinyl alcohol, approximately 1 wt% zirconium sulfate, approximately 1.5 wt% PEDOT:PSS, approximately 5 wt% MXene (Ti3C2Tx) and approximately 2 wt% calcium alginate microspheres, with the balance being deionized water.

[0150] The low modulus lower layer precursor solution (i.e., the second precursor solution) contains the following components: about 8 wt% polyvinyl alcohol, about 1 wt% chitosan (CS), about 1 wt% PEDOT:PSS, about 2 wt% MXene (Ti3C2Tx) and about 5 wt% calcium alginate microspheres, and the balance is deionized water.

[0151] (2) Preparation process:

[0152] S1. Prepare the first and second precursor solutions according to the above material ratios, stir them thoroughly, and let them stand at room temperature for 2 hours to ensure uniformity and the absence of bubbles.

[0153] S2. Inject 10 ml of the first precursor solution into a 5 cm diameter cylindrical mold and freeze it in a single direction on a freezing plate at approximately -80°C for 8 hours to obtain a high modulus precursor structure layer (i.e., the first precursor structure layer).

[0154] S3. Then, 5 ml of the second precursor liquid is taken to cover the above high modulus precursor structure layer and unidirectionally frozen at approximately -40°C for 4 hours to obtain a low modulus precursor structure layer (i.e., the second precursor structure layer), thereby forming a hydrogel precursor layer.

[0155] S4. Soak the hydrogel precursor layer in a 20°C water bath for 6 hours to remove the pre-embedded calcium alginate microspheres therein and form an open conductive network in the hydrogel matrix, and then freeze-dry it in a vacuum freeze dryer at -60°C for 24 hours to form a conductive hydrogel layer.

[0156] S5. Finally, using magnetron sputtering or electron beam evaporation, a metal such as gold is used to deposit multiple cross-shaped conductive patterns on the conductive hydrogel layer, forming a flexible electrode array. The conductive patterns are 200 μm long and 200 μm wide, with a line width of 10 μm. Adjacent conductive patterns are spaced 150 μm apart. Flexible leads are then connected to form a flexible hydrogel electrode array. This flexible electrode array corresponds to 128 signal acquisition channels.

[0157] The optical image of the cross electrode pattern of a flexible hydrogel array electrode prepared in this embodiment is as follows: Figure 4 As shown, the microstructure of the high modulus layer is as follows Figure 5-7 As shown in Figure 2, the microstructure of the low modulus layer is as follows: Figure 10-12 As shown, such porous microstructure and open network topology are conducive to the formation of ion channels and the construction of conductive paths.

[0158] Furthermore, the mechanical simulation diagram of the high modulus layer is as follows: Figure 8-9 As shown, the mechanical simulation diagram of the low modulus layer is as follows Figure 13-14The mechanical simulation diagram shows the stress distribution of the flexible hydrogel array electrode under compression, verifying its excellent cushioning and deformation capabilities, which are conducive to long-term wear and brain tissue adhesion.

[0159] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0160] Example 2

[0161] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0162] (1) Material ratio:

[0163] The high modulus upper layer precursor solution (i.e., the first precursor solution) contains the following components: approximately 12 wt% polyvinyl alcohol, approximately 0.8 wt% zirconium sulfate, approximately 1 wt% PEDOT:PSS, approximately 3.5 wt% MXene (Ti3C2Tx), and approximately 2 wt% calcium alginate microspheres, with the remainder being deionized water.

[0164] The low-modulus lower layer precursor solution (i.e., the second precursor solution) contained the following components: approximately 6.5 wt% polyvinyl alcohol, approximately 2 wt% chitosan (CS), approximately 0.5 wt% PEDOT:PSS, approximately 1.5 wt% MXene (Ti3C2Tx), and approximately 5 wt% calcium alginate microspheres, with the balance being deionized water. The sources of MXene, polyvinyl alcohol, zirconium sulfate, and calcium alginate microspheres used in this example were the same as in Example 1.

[0165] (2) Preparation process:

[0166] S1. Prepare the first and second precursor solutions according to the above material ratios, stir them thoroughly, and let them stand at room temperature for 2 hours to ensure uniformity and the absence of bubbles.

[0167] S2. Inject 10 ml of the first precursor solution into a 5 cm diameter cylindrical mold and freeze it in a single direction on a freezing plate at approximately -60°C for 10 hours to obtain a high modulus precursor structure layer (i.e., the first precursor structure layer).

[0168] S3. Then, 5 ml of the second precursor liquid is taken to cover the above high modulus precursor structure layer and unidirectionally frozen at approximately -30°C for 5 hours to obtain a low modulus precursor structure layer (i.e., the second precursor structure layer), thereby forming a hydrogel precursor layer.

[0169] S4. Same as step S4 in Example 1.

[0170] S5. Same as step S5 of Example 1.

[0171] The optical diagram of the cross electrode pattern of a flexible hydrogel array electrode prepared in this embodiment is shown in Figure 15 The key performance indicators are shown in Table 1.

[0172] Embodiment 3

[0173] A flexible hydrogel array electrode and a preparation method thereof are provided in this embodiment, which are as follows.

[0174] (1) Material ratio:

[0175] The high-modulus upper layer precursor solution (i.e., the first precursor solution) comprises the following components: about 10 wt% polyvinyl alcohol, about 0.5 wt% zirconium sulfate, about 0.1 wt% PEDOT:PSS, about 2 wt% MXene (Ti3C2Tx), and about 2 wt% calcium alginate microspheres, and the balance is deionized water.

[0176] The low-modulus lower layer precursor solution (i.e., the second precursor solution) comprises the following components: about 5 wt% polyvinyl alcohol, about 2 wt% chitosan (CS), about 0.1 wt% PEDOT:PSS, about 1 wt% MXene (Ti3C2Tx), and about 5 wt% calcium alginate microspheres, and the balance is deionized water.

[0177] The sources of MXene, polyvinyl alcohol, zirconium sulfate, and calcium alginate microspheres used in this embodiment are the same as those in Embodiment 1.

[0178] (2) Preparation process:

[0179] S1. The first precursor solution and the second precursor solution are prepared according to the above-mentioned material ratio, and are fully stirred and uniformly placed at room temperature for 2 hours to ensure uniformity and no air bubbles.

[0180] S2. 10 ml of the first precursor solution is first injected into a cylindrical mold with a diameter of 5 cm, and is placed on a freezing plate at about -40°C for unidirectional freezing, and the freezing time is maintained for 12 h to obtain a high-modulus precursor structure layer (i.e., the first precursor structure layer).

[0181] S3. Then 5 ml of the second precursor solution is covered on the above-mentioned high-modulus precursor structure layer and is unidirectionally frozen at about -20°C for 3 h to obtain a low-modulus precursor structure layer (i.e., the second precursor structure layer), thereby forming a hydrogel precursor layer.

[0182] S4. The same as step S4 of Embodiment 1.

[0183] S5. The same as step S5 of Embodiment 1.

[0184] The key performance indicators of a flexible hydrogel array electrode prepared in this embodiment are shown in Table 1.

[0185] Example 4

[0186] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0187] (1) Material ratio:

[0188] The first precursor solution contains the following components: about 5 wt% carbon nanotubes, about 1 wt% PEDOT:PSS, about 5 wt% polyethylene glycol (molecular weight 10,000), about 3 wt% chitosan, about 1 wt% ferric chloride particles, about 2 wt% gelatin microspheres, and the balance is deionized water.

[0189] The second precursor solution contains the following components: about 1 wt% MXene, about 0.5 wt% carbon nanotubes, about 0.5 wt% PEDOT:PSS, about 2 wt% polyethylene glycol (molecular weight 10,000), about 0.5 wt% chitosan, about 0.5 wt% zirconium sulfate, about 5 wt% gelatin microspheres, and the balance is deionized water.

[0190] The sources of MXene and chitosan used in this example are the same as those in Example 1.

[0191] (2) Preparation process:

[0192] S1. Prepare the first precursor solution and the second precursor solution according to the above material ratios.

[0193] S2. 10 ml of the first precursor solution was injected into a cylindrical mold with a diameter of 5 cm. The mold was then frozen in a single direction at approximately -50°C for 8 hours to obtain the first precursor structure layer.

[0194] S3. Then, 5 ml of the second precursor liquid is taken to cover the first precursor structure layer and frozen in one direction at about -30°C for 5 hours to obtain the second precursor structure layer, thereby forming a hydrogel precursor layer.

[0195] S4. Same as step S4 in Example 1.

[0196] S5. The same as step S5 of Example 1, except that the flexible electrode array corresponds to 256 signal acquisition channels.

[0197] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0198] Example 5

[0199] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0200] (1) Material ratio:

[0201] The first precursor solution comprises the following components: about 2 wt% carbon nanotubes, about 1.5 wt% PEDOT:PSS, about 2 wt% polyethylene glycol, about 2 wt% chitosan, about 0.5 wt% ferric chloride particles, about 2 wt% magnesium alginate microspheres, and the balance is deionized water.

[0202] The second precursor solution comprises the following components: about 0.5 wt % carbon nanotubes, about 0.5 wt % PEDOT:PSS, about 1 wt % polyethylene glycol, about 1 wt % chitosan, about 0.6 wt % ferric chloride particles, about 5 wt % magnesium alginate microspheres, and the balance is deionized water.

[0203] (2) Preparation process:

[0204] S1. Prepare the first precursor solution and the second precursor solution according to the above material ratios.

[0205] S2. 10 ml of the first precursor solution was injected into a cylindrical mold with a diameter of 5 cm. The mold was then frozen in a single direction at approximately -60°C for 6 hours to obtain the first precursor structure layer.

[0206] S3. Then, 5 ml of the second precursor liquid is taken to cover the first precursor structure layer and frozen in one direction at about -15°C for 4 hours to obtain the second precursor structure layer, thereby forming a hydrogel precursor layer.

[0207] S4. Same as step S4 in Example 1.

[0208] S5. The same as step S5 of Example 1, except that the flexible electrode array corresponds to 64 signal acquisition channels.

[0209] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0210] Example 6

[0211] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0212] (1) Material ratio:

[0213] The first precursor solution comprises the following components: about 3 wt% carbon nanotubes, about 1.5 wt% PEDOT:PSS, about 12 wt% polyvinyl alcohol, about 2 wt% polyethylene glycol, about 5 wt% chitosan, about 0.8 wt% zirconium sulfate, about 2 wt% calcium alginate microspheres, and the balance is deionized water.

[0214] The second precursor solution comprises the following components: about 1 wt % carbon nanotubes, about 6 wt % polyvinyl alcohol, about 1 wt % polyethylene glycol, about 0.1 wt % PEDOT:PSS, about 2.5 wt % chitosan, about 0.5 wt % ferric chloride particles, about 5 wt % magnesium alginate microspheres, and the balance is deionized water.

[0215] (2) Preparation process: basically the same as Example 5.

[0216] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0217] Example 7

[0218] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0219] (1) Material ratio:

[0220] The components of the first precursor solution in this embodiment are substantially the same as those in Example 5, with the only difference being that the carbon nanotubes are replaced by silver nanowires of the same mass.

[0221] The components of the second precursor solution in this embodiment are substantially the same as those of the first precursor solution in Example 5, with the only difference being that the carbon nanotubes are replaced by silver nanowires of the same mass.

[0222] (2) Preparation process: basically the same as Example 5.

[0223] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0224] Example 8

[0225] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0226] (1) Material ratio:

[0227] The components of the first precursor solution in this embodiment are substantially the same as those in Example 5, with the only difference being that the carbon nanotubes are replaced by titanium nanosheets of the same mass.

[0228] The components of the second precursor solution in this embodiment are substantially the same as those of the first precursor solution in Example 5, with the only difference being that the carbon nanotubes are replaced by titanium nanosheets of the same mass.

[0229] (2) Preparation process: basically the same as Example 5.

[0230] The key performance indicators of the flexible hydrogel array electrode prepared in this example are shown in Table 1.

[0231] Example 9

[0232] This embodiment provides a flexible hydrogel array electrode and a method for manufacturing the same, as follows:

[0233] (1) Material ratio: the same as that in Example 3.

[0234] (2) Preparation process: the same as steps S1, S2, S3, and S5 in Example 3;

[0235] S4: Soaking the prepared hydrogel precursor layer in a sodium hydroxide solution with a mass fraction of about 5 wt % for 6 hours to etch the open conductive network structure in the hydrogel precursor layer.

[0236] The optical image of the cross electrode pattern of a flexible hydrogel array electrode prepared in this embodiment is as follows: Figure 16 The key performance indicators are shown in Table 1.

[0237] Comparative Example 1

[0238] The method for preparing a flexible hydrogel array electrode provided in this comparative example is different from that in Example 1 only in that zirconium sulfate is not added to the upper precursor solution and the lower precursor solution in this comparative example.

[0239] The key performance indicators of the flexible hydrogel array electrode prepared in this comparative example are shown in Table 1.

[0240] Comparative Example 2

[0241] The preparation method of a flexible hydrogel array electrode provided in this comparative example is basically the same as that in Example 3, with the only difference being:

[0242] In this comparative example, zirconium sulfate, PEDOT:PSS, and MXene (Ti3C2Tx) were not added to the upper layer precursor solution; and PEDOT:PSS and MXene (Ti3C2Tx) were not added to the lower layer precursor solution.

[0243] The key performance indicators of the flexible hydrogel array electrode prepared in this comparative example are shown in Table 1.

[0244] Comparative Example 3

[0245] The preparation method of a flexible hydrogel array electrode provided in this comparative example is basically the same as that of Example 8, with the only difference being:

[0246] In this comparative example, no sacrificial template agent was added to the upper layer precursor solution and the lower layer precursor solution.

[0247] The key performance indicators of the flexible hydrogel array electrode prepared in this comparative example are shown in Table 1.

[0248] Comparative Example 4

[0249] The preparation method of a flexible hydrogel array electrode provided in this comparative example is basically the same as that in Example 1, except that it only contains the high modulus upper layer precursor solution (i.e., the first precursor solution) in Example 1, which contains the following components: approximately 15 wt% polyvinyl alcohol, approximately 1 wt% zirconium sulfate, approximately 1.5 wt% PEDOT:PSS, approximately 5 wt% MXene (Ti3C2Tx) and approximately 2 wt% calcium alginate microspheres, with the balance being deionized water.

[0250] In step S2, 15 ml of the first precursor solution was injected into a cylindrical mold with a diameter of 5 cm, and then placed on a freezing plate at approximately -80°C for unidirectional freezing for 8 hours. Furthermore, the operation of step S3 was omitted.

[0251] The key performance indicators of the flexible hydrogel array electrode prepared in this comparative example are shown in Table 1.

[0252] Comparative Example 5

[0253] The preparation method of a flexible hydrogel array electrode provided in this comparative example is basically the same as that in Example 1, except that it only contains the low modulus lower layer precursor solution (i.e., the second precursor solution) in Example 1, which contains the following components: approximately 8 wt% polyvinyl alcohol, approximately 1 wt% chitosan (CS), approximately 1 wt% PEDOT:PSS, approximately 2 wt% MXene (Ti3C2Tx) and approximately 5 wt% calcium alginate microspheres, with the balance being deionized water.

[0254] The operation of step S2 is omitted. In step S3, 15 ml of the second precursor solution is injected into a cylindrical mold with a diameter of 5 cm, and then unidirectionally frozen at about -40°C for 4 hours.

[0255] The key performance indicators of the flexible hydrogel array electrode prepared in this comparative example are shown in Table 1.

[0256] Table 1 Key performance indicators of flexible hydrogel array electrodes prepared in Examples and Comparative Examples

[0257] Performance indicators Impedance (@1kHz) Young's modulus (low modulus layer) Young's modulus (high modulus layer) Tensile fracture strain Fatigue recovery compression rate (100 times) MRI artifact area (3.0T) MRI artifact area (3.0T) reduction rate Number of buildable channels Biocompatibility Cell viability (%) Fit (scalp model) Example 1 250Ω 0.3MPa 2MPa 200% 91.6% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥128 good ≥85% ≥80% Example 2 350Ω 0.25MPa 1.5MPa 280% 85.6% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥64 good ≥85% ≥85% Example 3 >500Ω 0.1MPa 1MPa 350% 83.7% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 excellent ≥95% ≥95% Example 4 >300Ω 0.2MPa 1.5MPa 150% 82.9% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥256 good ≥85% ≥85% Example 5 >1500Ω 0.15MPa 2MPa 210% 85.7% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥64 good ≥85% ≥85% Example 6 >1000Ω 0.1MPa 1MPa 300% 75.1% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 good ≥85% ≥90% Example 7 >150Ω 0.08MPa 1.1MPa 450% 88.2% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 excellent ≥95% ≥95% Example 8 ﹥800Ω 0.12MPa 1.5MPa 350% 78.5% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 excellent ≥95% ≥95% Example 9 >400Ω 0.05MPa 1MPa 150% 70.5% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 excellent ≥95% ≥98% Comparative Example 1 >400Ω 0.06MPa 1MPa 150% 75.2% <![CDATA[2mm 2 ]]> Reduce by more than 60% ≥18 good ≥85% ≥98% Comparative Example 2 >50kΩ 0.08MPa 1.5MPa 250% 63.4% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥18 good ≥85% ≥98% Comparative Example 3 >400Ω 0.8MPa 5MPa 200% 92.5% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥32 generally ≥65% ≤40% Comparative Example 4 250Ω — 2MPa 200% 96% <![CDATA[1mm 2 ]]> Reduce by more than 90% ≥128 good ≥85% ≤30% Comparative Example 5 250Ω 0.3MPa — 200% 80% 1 mm 2 ]] Reduce by more than 90% ≥128 good ≥85% ≥85%

[0258] Test Example 1

[0259] The surface potential performance of the flexible hydrogel array electrodes of Example 1 and Comparative Example 1 was tested by Kelvin probe force microscopy (KPFM). LSFG was the electrode of Comparative Example 1, and LSFG-Zr 4+ For Example 1, the test results are as follows Figure 17 As shown, it can be seen that the flexible hydrogel array electrode of Example 1 has more uniform and stable surface electrical properties, and enhances signal acquisition consistency and anti-noise capability.

[0260] Test Example 2

[0261] The magnetic susceptibility test of the flexible hydrogel array electrodes of Example 1 and Comparative Example 1 was performed. LSFG was the electrode of Comparative Example 1, and LSFG-Zr 4+ For Example 1, the test results are as follows Figure 18-21 As shown, the magnetic susceptibility value of the flexible hydrogel array electrode of Example 1 is lower than that of human tissue, which effectively avoids signal distortion in the magnetic sensitive area.

[0262] Test Example 3

[0263] The flexible hydrogel array electrodes of Example 1 and Comparative Example 1 were subjected to mechanical properties-fatigue resistance tests. LSFG was used as Comparative Example 1, and LSFG-Zr 4+ For Example 1, the test results are as follows Figure 22-27 As shown. Figure 22 It can be seen that the flexible hydrogel array electrode of Example 1 exhibits a higher compressive modulus and a larger deformation range, indicating that it has both structural strength and flexibility. Figure 23 It can be seen that the stress decay rate of the flexible hydrogel array electrode of Example 1 is slow, indicating that it has a more stable stress retention ability and is suitable for long-term brain tissue adhesion. Figures 24-25 It can be seen that the stress curve of the flexible hydrogel array electrode of Example 1 can rebound stably in each cycle with almost no plastic deformation, verifying its good fatigue tolerance. Figures 26-27 It can be seen that the stress of the flexible hydrogel array electrode of Comparative Example 1 gradually decays, the curve shows a trend of plastic deformation, there is obvious fatigue softening, and the adaptability is poor.

[0264] Test Example 4

[0265] The flexible hydrogel array electrodes of Example 1 and Comparative Example 1 were tested for modulus, viscosity and rheological properties. LSFG was used as Comparative Example 1, and LSFG-Zr 4+ For Example 1, the test results are as follows Figures 28-30 As shown. Figure 28 It can be seen that the flexible hydrogel array electrode of Example 1 exhibits viscoelastic behavior at different frequencies. Figure 29 It can be seen that the tanδ value of the flexible hydrogel array electrode of Example 1 changes with frequency, indicating its viscoelastic transition ability, which helps to adapt to brain tissue movement. Figure 30 It can be seen that the rheological test results of the flexible hydrogel array electrode of Example 1 show that it has excellent mechanical dynamic stability under physiological environment.

[0266] Test Example 5

[0267] The electrical performance of the flexible hydrogel array electrodes of Example 1 and Comparative Example 1 was tested, and the test results are as follows: Figures 31-34 As shown. LSFG is comparative example 1, LSFG-Zr 4+ This is Example 1. Figure 31 It can be seen that the flexible hydrogel array electrode of Example 1 exhibits lower interface impedance. Figure 32 It can be seen that the flexible hydrogel array electrode of Example 1 exhibits stable and efficient ion / electronic conductivity. Figures 33-34 It can be seen that the flexible hydrogel array electrode of Example 1 has good charge transfer performance, which improves the accuracy and response sensitivity of EEG signals.

[0268] Test Example 6

[0269] The flexible hydrogel array electrodes of Example 1, Comparative Example 1, and a blank control group were subjected to a biocompatibility experiment.

[0270] Material treatment: The flexible hydrogel array electrode samples of Example 1 and Comparative Example 1, as well as the blank sample without flexible hydrogel array electrodes, were cut into Φ10 mm discs (about 0.1 mm thick), washed three times with sterile PBS buffer, and sterilized under UV for 30 min.

[0271] Cells used: Mouse fibroblasts (L929 cells) and human dermal fibroblasts (HDFs cells)

[0272] Specific experimental methods:

[0273] (1) Cell viability assay of mouse fibroblasts (L929 cells)

[0274] Experimental purpose: To evaluate the effect of flexible hydrogel array electrodes on the survival rate of L929 cells.

[0275] Experimental process: The pre-treated flexible hydrogel array electrode samples of Example 1 and Comparative Example 1 and blank samples were placed in a 24-well plate; 1×10 4 L929 cells (200 μL cell suspension); culture time was set at 1 day, 2 days, and 3 days; each sample was taken at each time point, 20 μL of 10% cell counting reagent working solution (CCK-8 working solution) was added, and incubated for 2 hours; the absorbance of each sample at 450 nm was measured using a microplate reader.

[0276] The data processing adopts the following formula:

[0277] Relative cell viability = (OD value of experimental group - OD value of blank well) / (OD value of control group - OD value of blank well) × 100%.

[0278] The experimental results are as follows Figures 35-37 As shown, it can be seen that the flexible hydrogel array electrode of Example 1 is non-toxic to cells, and its L929 cells still have good cell activity.

[0279] (2) Immunofluorescence staining of live and dead cells of human dermal fibroblasts (HDFs)

[0280] Experimental purpose: To observe the attachment, growth and morphology of HDFs cells on the surface of flexible hydrogel array electrodes.

[0281] Experimental process: The pre-treated flexible hydrogel array electrode samples of Example 1 and Comparative Example 1 and blank samples were placed in 12-well plates respectively; HDFs cells (density: 1×10 4 cells / cm²); on the first, second, and third days, the cells were stained with live / dead cell double staining reagent (Calcein-AM marked live cells were green, PI stained dead cells were red), and the morphology and proliferation of HDFs cells in each sample were quantitatively analyzed by image analysis.

[0282] Among them, image quantitative analysis mainly includes: the number and density of living cells; cell area and extension length; the proportion of dead cells; the uniformity of cell distribution; key points for observing cell morphology: whether they grow adherently; whether multicellular aggregates are formed; whether there are morphological abnormalities such as rounding, rupture, floating, etc.; and observation of cell distribution, density and morphology using a laser confocal microscope.

[0283] The experimental results are as follows Figure 38 As shown, it can be seen that the flexible hydrogel array electrode of Example 1 is non-toxic to cells and exhibits good cell compatibility.

[0284] Test Example 7

[0285] The flexible hydrogel array electrode of Example 1 was used for brain nerve acquisition. The flexible hydrogel array electrode was attached to the skin surface of the subject's head and the subject's brain nerve signals were acquired in a magnetic resonance environment. The test results are shown in FIG. Figure 39 As shown. Figure 39 It can be seen that the brain nerve signals show clear α-wave, β-wave and other frequency band signals, indicating that the flexible hydrogel array electrode of Example 1 has excellent acquisition performance.

[0286] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all respects and are not intended to limit the present invention, the scope of which is defined solely by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0287] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0288] Although the present invention has been described with reference to illustrative embodiments, it will be understood by those skilled in the art that various other changes, omissions, and / or additions may be made and that substantial equivalents may be substituted for the elements of the embodiments without departing from the spirit and scope of the present invention. Additionally, many modifications may be made to adapt specific circumstances or materials to the teachings of the present invention without departing from the scope of the present invention. Therefore, it is not intended herein to limit the present invention to the disclosed specific embodiments for carrying out the present invention, but rather to include all embodiments within the scope of the appended claims. Furthermore, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but rather uses the terms first, second, etc. to distinguish one element from another.

Claims

1. A flexible hydrogel array electrode, characterized in that: It includes a flexible low magnetic susceptibility conductive hydrogel layer and a flexible electrode array arranged in a stacked manner; The conductive hydrogel layer comprises a paramagnetic material and a diamagnetic material, wherein the conductive substance in the diamagnetic material is used to form an ion conductive network, and the non-conductive substance in the diamagnetic material is used to form a hydrogel matrix, and the paramagnetic material is dispersed in the hydrogel matrix; At the same time, the conductive hydrogel layer has a porous structure, and more than 70% of the holes in the porous structure are oriented along the thickness direction of the hydrogel layer; Furthermore, an open conductive network structure is distributed within the conductive hydrogel layer, the open conductive network structure comprising an interpenetrating structure of an electronic conductive network and an ion conductive network, the electronic conductive network comprising a continuous three-dimensional conductive network structure formed by interconnecting the paramagnetic materials, the ion conductive network comprising a continuous conductive path formed by the hydrogel matrix, and the open conductive network structure being electrically connected to the flexible electrode array; The conductive hydrogel layer further comprises a first structural layer and a second structural layer; the first structural layer is stacked on the second structural layer and has a directional microporous structure; the second structural layer has a large-pore flexible network structure; the flexible electrode array is stacked on the first structural layer; Among them, the Young's modulus of the first structural layer is greater than the Young's modulus of the second structural layer, the content of paramagnetic material in the first structural layer is greater than the content of paramagnetic material in the second structural layer, the content of diamagnetic material in the first structural layer is greater than the content of diamagnetic material in the second structural layer, and the average pore size of the holes contained in the large-pore flexible network structure is greater than the average pore size of the holes contained in the oriented microporous structure.

2. The flexible hydrogel array electrode according to claim 1, characterized in that: The conductive hydrogel layer has pores, the pores are interconnected, the porosity is 60-90%, and the overall connectivity of the pores is greater than 70%; And / or, the pore channel spacing in the open conductive network structure is 20-200 μm, and the conductive coupling density is 0.1-0.8; and / or, the Young's modulus of the conductive hydrogel layer increases in a direction approaching the flexible electrode array; And / or, the flexible electrode array includes a plurality of conductive pattern structures arranged in an array; And / or, the flexible electrode array corresponds to 32 to 256 signal acquisition channels; and / or, the paramagnetic material comprises a combination of one or more of MXene, silver nanowires, carbon nanotubes, or titanium nanosheets; And / or, the diamagnetic material includes a non-conductive substance and a conductive substance, the non-conductive substance includes a polymer, the polymer includes a combination of one or more of polyvinyl alcohol, chitosan or polyethylene glycol, the conductive substance includes a conductive agent, the conductive agent includes a combination of one or more of conductive polymers, graphene or metal salts, the conductive polymer includes PEDOT:PSS, and the metal salt includes at least any one of zirconium sulfate, calcium chloride, and ferric chloride.

3. The flexible hydrogel array electrode according to claim 2, wherein: The Young's modulus of the first structural layer is 0.5-2 MPa, the diamagnetic material content is 5-15 wt%, the paramagnetic material content is 2-5 wt%, and the pore diameter of the oriented microporous structure is 20-50 μm; And / or, the thickness of the first structural layer is 0.1-2 mm; And / or, the Young's modulus of the second structural layer is 0.05-0.35 MPa, the diamagnetic material content is 1-9 wt %, the paramagnetic material content is 0.1-2 wt %, and the pore diameter of the pores contained in the large-pore flexible network structure is 50-150 μm; And / or, the thickness of the second structural layer is 0.1-1 mm; and / or, the second structural layer and the first structural layer are formed as one body; And / or, the diameter of the ion channel formed in the first structural layer is 1-50 μm, and the diameter of the ion channel formed in the second structural layer is 50-300 μm; And / or, the length and width of the conductive pattern structure are 1-20 mm, and the spacing between adjacent conductive pattern structures is 20-200 μm; And / or, the conductive pattern structure has a shape including a cross or a circle.

4. The method for preparing the flexible hydrogel array electrode according to any one of claims 1 to 3, wherein: The method comprises a first step of preparing a flexible low magnetic susceptibility conductive hydrogel layer by a directional freezing-induced phase separation technique and a second step of preparing a flexible electrode array; The first step includes: performing directionally freezing with a first precursor liquid at a first temperature to form a first precursor structure layer, and performing directionally freezing with a second precursor liquid at a second temperature to form a second precursor structure layer, and the first precursor structure layer and the second precursor structure layer are stacked; performing freeze-drying or thawing-cross-linking treatment on the first precursor structure layer and the second precursor structure layer to form a hydrogel precursor layer; Processing an open conductive network structure in the hydrogel precursor layer to form the conductive hydrogel layer; The first precursor liquid and the second precursor liquid both contain paramagnetic material, diamagnetic material and solvent, and the concentration of paramagnetic material in the first precursor liquid is greater than the concentration of paramagnetic material in the second precursor liquid, the concentration of diamagnetic material in the first precursor liquid is greater than the concentration of diamagnetic material in the second precursor liquid, and the first temperature is lower than the second temperature.

5. The method according to claim 4, wherein: The first precursor solution comprises 2-5 wt% MXene and / or 2-5 wt% carbon nanotubes, and a combination of one or more of 0.1-1.5 wt% PEDOT:PSS, 10-15 wt% polyvinyl alcohol and / or 2-5 wt% polyethylene glycol, 1-5 wt% chitosan, and 0.5-1 wt% metal salt; And / or, the second precursor solution comprises 1-2 wt% MXene and / or 0.5-1 wt% carbon nanotubes, and a combination of one or more of 0.1-1 wt% PEDOT:PSS, 5-8 wt% polyvinyl alcohol and / or 1-2 wt% polyethylene glycol, 0.5-2.5 wt% chitosan, and 0.5-1 wt% metal salt; And / or, the directional freezing is carried out under unidirectional temperature gradient conditions; And / or, the first temperature is -40°C to -80°C, and the second temperature is -10°C to -40°C; And / or, the first precursor liquid is directionally frozen at the first temperature for 6 to 12 hours, and the second precursor liquid is directionally frozen at the second temperature for 3 to 6 hours; and / or, the solvent comprises water; and / or, processing the open conductive network structure in the hydrogel precursor layer at least by microetching or template sacrificial method; And / or, the second step includes: preparing the flexible electrode array by at least laser etching or microelectronic printing.

6. The method according to claim 5, wherein: The first precursor liquid and the second precursor liquid both contain a sacrificial template, and the sacrificial template is distributed in the first precursor structure layer and the second precursor structure layer; wherein the mass fraction of the sacrificial template in the first precursor liquid is 1-2 wt %, and the mass fraction of the sacrificial template in the second precursor liquid is 2-5 wt %; The preparation method specifically includes: removing at least a portion of the sacrificial template in the hydrogel precursor layer, thereby processing the open conductive network structure in the hydrogel precursor layer.

7. Use of the flexible hydrogel array electrode according to any one of claims 1 to 3 in preparing flexible electronic devices, intelligent protection systems or wearable neural interface platforms.

8. Use of the flexible hydrogel array electrode according to any one of claims 1 to 3 in preparing a flexible brain-computer interface.

9. A magnetic-electric dual-mode neural signal monitoring and control system, characterized in that: The flexible hydrogel array electrode comprises the flexible hydrogel array electrode according to any one of claims 1 to 3.

10. A multimodal signal acquisition and fusion method, characterized in that: include: Providing a flexible hydrogel array electrode according to any one of claims 1 to 3; Attaching the flexible hydrogel array electrode to the surface of the subject's skin, and making the flexible electrode array therein contact with the subject's skin; Examining a subject with a magnetic resonance device, and simultaneously collecting biological signals of the subject in a magnetic resonance environment using at least the flexible hydrogel array electrode, wherein the biological signals include one or more of brain nerve signals, electrocardiogram signals, and electromyography signals; The collected magnetic resonance signal is fused with the biological signal.

11. The multimodal signal acquisition and fusion method according to claim 10, characterized in that: Specifically include: attaching the flexible hydrogel array electrode to the surface of the subject's head skin, and collecting the subject's brain neural signals in the magnetic resonance environment; And / or, the magnetic field strength of the magnetic resonance environment is above 1.5T.

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