Flexible microelectrode arrays and their fabrication methods, brain-computer interface devices

Abstract

This application discloses a flexible microelectrode array and its fabrication method, as well as a brain-computer interface device, relating to the field of artificial intelligence. It includes: a flexible substrate, multiple brain signal metal electrodes, a first metal conductive assembly, and a second metal conductive assembly. The flexible substrate has a first side and a second side disposed opposite to each other. The multiple brain signal metal electrodes are disposed on the first side, forming an electrode array. The first metal conductive assembly is disposed on the second side of the flexible substrate and encapsulated within the flexible substrate, including multiple first connection sites and multiple connecting wires. The second metal conductive assembly includes multiple second connection sites exposed on the flexible substrate, the second connection sites being disposed on either the first or second side of the flexible substrate. The multiple first connection sites are respectively connected to the multiple brain signal metal electrodes and simultaneously connected to the multiple second connection sites via multiple connecting wires. The multiple second connection sites are used for communicative connection with a processor.

Description

Technical Field

[0001] This application relates to the field of artificial intelligence technology, and in particular to a flexible microelectrode array and its fabrication method, and a brain-computer interface device. Background Technology

[0002] Flexible microelectrode arrays possess excellent flexibility and stretchability, enabling better adhesion to the nerve cell interface. This allows for long-term stable culture of neurons and real-time signal detection, while also improving the sensitivity and quality of neurophysiological signal detection. In neuroscience, flexible microelectrode arrays can be used to study brain function and nervous system diseases. By recording the electrical activity of different brain regions, their functional state and pathological changes can be understood. They can also be used in brain-computer interface research, facilitating direct communication between the human brain and computers or other devices.

[0003] Currently, flexible electrode structures used in the cerebral cortex are generally planar thin-film brain signal metal electrodes with a certain height. In the long-term implantation environment of the brain, there are problems such as multiple encapsulation times, large implantation wounds, and significant damage to the human body. Summary of the Invention

[0004] This application provides a flexible microelectrode array for brain-computer interfaces, its preparation method, and a brain-computer interface device, to solve the problems of multiple encapsulation cycles, large implantation wounds, and significant damage to the human body.

[0005] In a first aspect, this application provides a flexible microelectrode array for brain-computer interfaces, comprising:

[0006] A flexible substrate having a first side and a second side disposed opposite to each other;

[0007] Multiple brain signal metal electrodes are disposed on the first side and spaced apart to form an electrode array;

[0008] A first metal conductive assembly, disposed on the second side of the flexible substrate and encapsulated within the flexible substrate, includes multiple first connection points and multiple connecting wires; and,

[0009] The second metal conductive assembly includes a plurality of second connection sites exposed on the flexible substrate, the second connection sites being disposed on a first side or a second side of the flexible substrate;

[0010] The plurality of first connection sites are respectively connected to the plurality of brain signal metal electrodes, and are also respectively connected to the plurality of second connection sites through the plurality of connecting wires;

[0011] Multiple second connection points are used for communication connections with the processor.

[0012] In this application, when the flexible microelectrode array is implanted in the brain, the brain signal metal electrode makes contact with the brain's nerves. The first metal connecting component, connected to the brain signal metal electrode, transmits the brain signals received by the brain signal metal electrode to the second metal connecting component. The second metal connecting component transmits the signals to the processor through connection points to achieve control or response. Since multiple first connection points are connected to multiple brain signal metal electrodes respectively, and simultaneously connected to multiple second connection points respectively through multiple connecting wires, and the multiple first connection points and multiple connecting wires are encapsulated within a flexible substrate, there is no need to additionally set up leads connecting the first connection points to the second connection points. The signal connection between the first connection points and the second connection points is directly achieved through patterned connecting wires. Since the second connection points are exposed, they can be directly soldered to the processor's solder point array. After soldering, only the processor and electrode array need to be integrated into a single package to achieve the encapsulation and protection of the entire flexible microelectrode array, without the need for additional encapsulation of the leads connecting the first connection points to the second connection points, and without the need to bring out the leads. This reduces the volume of the flexible microelectrode array, resulting in a smaller implantation wound and less damage to brain tissue.

[0013] It should be noted that there are two forms in which the second connection sites are located on the first or second side of the flexible substrate: one is that all the second connection sites are located on the second side of the flexible substrate; the other is that all the second connection sites are located on the first side of the flexible substrate.

[0014] The first metal conductive assembly is encapsulated within the insulating layer on the second side of the flexible substrate, enabling fixation and protection of the electrodes, reducing electrode movement, and minimizing damage to brain tissue. The second metal conductive assembly is exposed outside the insulating layer on either the first or second side of the flexible substrate, allowing direct soldering to the processor's solder array without the need for additional leads from the electrode array or secondary encapsulation of those leads. This achieves good signal conduction without complex wiring, large-area wiring, or large implantation wounds.

[0015] It should be noted that in some embodiments, the brain signal metal electrodes can adopt a protruding tip electrode structure design, which improves the mechanical strength of the electrodes, enhances the mechanical properties and ductility for long-term implantation, and meets the requirements for long-term implantation. Flexible tip electrode arrays are more easily adapted to the curvature of the cerebral cortex, reducing displacement and slippage in long-term implantation environments, resulting in more accurate signal transmission. To improve the biocompatibility of the flexible microelectrode array, multiple protrusions with mounting channels can be provided on the first side of the flexible substrate. The brain signal metal electrodes are placed within the mounting channels of these protrusions, with the tips exposed. This increases the pressure on the tips during implantation, reduces implantation resistance, improves the accuracy of signal transmission, and reduces damage to brain tissue from rigid metal materials.

[0016] This application does not limit the shape of the flexible microelectrode array, which can be circular, square, triangular, rhomboid or polygonal.

[0017] In some embodiments, the second metal conductive component is disposed around the periphery of the first metal conductive component. Since the first metal conductive component is encapsulated within an insulating layer on the second side of the flexible substrate and connected to the plurality of brain signal metal electrodes respectively, and the second metal conductive component is exposed outside the insulating layer on the second side of the flexible substrate for connection to the processor, in order to reduce interference between the second metal conductive component and the first metal conductive component, the second metal conductive component is disposed around the periphery of the first metal conductive component, such that the first metal conductive component is located in the middle and the second metal conductive component is located at the edge. This also reduces the wiring distance of the second metal conductive component and facilitates connection to the processor.

[0018] In some embodiments, the flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone, a biocompatible material that reduces the risk of rejection; and / or,

[0019] The brain signal metal electrode is made of at least one of gold, silver, copper and platinum. The brain signal metal electrode has good mechanical strength and ductility, which meets the requirements for long-term implantation. Using at least one of the above materials can improve the stability of the brain signal metal electrode and reduce the harm to the human body caused by electrode corrosion.

[0020] In some embodiments, the number of brain signal metal electrodes is 8 to 64. The electrode array formed by 8 to 64 brain signal metal electrodes is usually a low-throughput electrode array with low signal volume and low transmission resistance. The integrated packaging can realize direct data transmission while reducing the transmission pressure caused by excessive data volume.

[0021] The shapes of the first and second connection sites include, but are not limited to, square, circular, triangular, rhomboid, trapezoidal, or polygonal. The positions of the second connection sites can be equally spaced or non-equally spaced, and can be set only on one side of the flexible microelectrode array, on opposite or adjacent sides, or around the perimeter.

[0022] It should be noted that the position and number of the first connection points correspond one-to-one with the brain signal metal electrodes, and the number of the second connection points corresponds to the number of the first connection points. That is, each brain signal metal electrode is connected to one first connection point, and each first connection point is connected to one second connection point through a connecting wire. This enables the transmission of the signal from each brain signal metal electrode to the processor. The signals from each electrode do not interfere with each other and are transmitted independently.

[0023] It should be noted that the thickness of the flexible substrate can be 10–70 μm. The total height of the brain signal metal electrode can be 0.5–2 mm, the exposed height can be 0.1–0.5 mm, and the diameter can be 0.1–1.5 mm. The shape of the protrusion can be cylindrical or conical; to improve implantation efficiency and reduce implantation resistance, the protrusion is usually conical.

[0024] Secondly, this application provides a method for fabricating a flexible microelectrode array, comprising the following steps:

[0025] A flexible substrate with multiple spaced protrusions on one side was fabricated.

[0026] A metal conductive layer containing multiple connection sites and connecting wires is fabricated on the side of the flexible substrate without protrusions;

[0027] A flexible substrate material is used to encapsulate the connection sites and connecting wires of a portion of the metal conductive layer to form multiple first connection sites and multiple connecting wires of a first metal conductive assembly. Another portion of the connection sites of the metal conductive layer is exposed to form multiple second connection sites of a second metal conductive assembly.

[0028] Brain signal metal electrode mounting channels are formed on the protrusions of a flexible substrate. Brain signal metal electrodes are fabricated within the mounting channels and connected to a first metal conductive component to obtain a flexible microelectrode array.

[0029] By fabricating a metal conductive layer containing multiple connection sites and connecting wires on the protrusion-free side of a flexible substrate, and encapsulating part of the connection sites of the metal conductive layer with an insulating material to form a first metal conductive component, while exposing the other part of the connection sites of the metal conductive layer to form a second metal conductive component, reliable communication between the first and second metal conductive components can be achieved. Both metal conductive components can be formed in a single molding process. Furthermore, by forming brain signal metal electrode mounting channels on the protrusions of the flexible substrate, and fabricating brain signal metal electrodes within these channels, which are then connected to the first metal conductive component, a flexible microelectrode array is obtained. This allows for customization of the number and size of electrodes according to specific application requirements, and the design of electrode shapes suitable for different brain regions, offering greater flexibility and versatility. By patterning during the fabrication of the metal conductive layer, multiple first connection points and multiple connecting wires of the first metal conductive component, as well as multiple second connection points of the second metal conductive component, can be formed in one step. By encapsulating the multiple first connection points and multiple connecting wires with a flexible substrate material, a reliable connection between the first connection points and the second connection points can be achieved. There is no need to lead out additional leads from the first connection points, nor is there a need to encapsulate the leads. The structure is simple, and the data transmission is direct and accurate.

[0030] Insulating layer materials include, but are not limited to, flexible materials with good biocompatibility such as PDMS (polydimethylsiloxane), PMMA (polymethyl methacrylate), PI (polyimide), Parylene-C (para-xylene polymer), and silicone. Using the same material as the flexible substrate can further improve flexibility and biocompatibility. Methods for forming the insulating layer include, but are not limited to, thin film deposition processes (CVD, PVD), spin coating processes, stencil casting processes, and electrochemical deposition processes.

[0031] In some embodiments, fabricating a flexible substrate with multiple spaced protrusions on one side includes:

[0032] A flexible mold layer is fabricated on a substrate;

[0033] Multiple spaced tapered holes are cut into the flexible mold layer;

[0034] A flexible substrate with multiple spaced protrusions is prepared on the side of the flexible mold layer containing a tapered hole.

[0035] By cutting multiple spaced-apart tapered holes in a flexible mold layer, a flexible substrate with multiple spaced-apart protrusions is prepared on the side of the flexible mold layer containing the tapered holes. This method allows for the fabrication of a flexible substrate with multiple spaced-apart protrusions using a mold, and the shape of the flexible substrate can be changed by altering the shape of the mold, offering greater flexibility and simplicity. Subsequently, the flexible mold layer and substrate can be removed by demolding. The substrate can be a rigid material, including but not limited to silicon wafers and quartz sheets, which improves the support strength of the flexible substrate during fabrication and reduces deformation. The flexible substrate with multiple spaced-apart protrusions can be fabricated using thin-film deposition processes (CVD, PVD), template casting processes, and electrochemical deposition processes.

[0036] In some embodiments, fabricating a metal conductive layer containing multiple connection sites and connecting wires on the non-protrusion side of the flexible substrate includes:

[0037] Photoresist was spin-coated onto a flexible substrate to obtain a photoresist mask;

[0038] A metal layer is prepared under the cover of a photoresist mask, and the photoresist is removed to obtain a metal conductive layer containing multiple connection sites and connecting wires.

[0039] Since the metal conductive layer is not a flat plane, but rather forms different conductive layer patterns based on the positions of the brain signal metal electrodes and the wires connecting multiple brain signal metal electrodes, to prepare a metal conductive layer with a specific pattern, a photoresist mask is used. After preparing the metal layer, the photoresist is removed, resulting in a metal conductive layer containing multiple connection sites and connecting wires. The photoresist can be either positive or negative; positive photoresist cures under light, while negative photoresist dissolves under light. Methods for preparing the metal layer include, but are not limited to, thin film deposition processes (CVD, PVD, evaporation), template casting processes, electrochemical deposition processes, electroplating processes, and machining processes.

[0040] In some embodiments, brain signal metal electrode mounting channels are formed on the protrusions of the flexible substrate, brain signal metal electrodes are fabricated within the mounting channels, and connected to a first metal conductive component to obtain a flexible microelectrode array:

[0041] Methods for forming brain signal metal electrode mounting channels include laser cutting or dry etching. By forming these channels through laser cutting or dry etching of a flexible mold layer, the number, shape, and position of the brain signal metal electrodes can be better controlled; and / or,

[0042] Methods for preparing brain signal metal electrodes include any one of electrochemical deposition, capillary effect, and metal welding. By using electrochemical deposition, capillary effect, and metal welding to prepare brain signal metal electrodes, the amount of metal electrode prepared can be controlled to achieve the desired effect.

[0043] In some embodiments, the flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone, a biocompatible material that reduces the risk of rejection; and / or,

[0044] The brain signal metal electrode is made of at least one of gold, silver, copper and platinum. The brain signal metal electrode has good mechanical strength and ductility, which meets the requirements for long-term implantation. Using at least one of the above materials can improve the stability of the brain signal metal electrode and reduce the harm to the human body caused by electrode corrosion.

[0045] Thirdly, this application proposes a brain-computer interface device, including the flexible microelectrode array of the first aspect of this application. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of a flexible microelectrode array structure according to an embodiment of this application.

[0048] Figure 2 This is a bottom view of a flexible microelectrode array structure according to an embodiment of this application.

[0049] Figure 3 This is a cross-sectional view of a flexible microelectrode array structure according to an embodiment of this application.

[0050] Figure 4 This is a schematic diagram of the process flow for a flexible microelectrode array fabrication method according to an embodiment of this application.

[0051] Explanation of icon numbers:

[0052] 100 Flexible microelectrode array; 1 Flexible substrate; 11 Protrusion; 12 Insulating layer; 2 Brain signal metal electrode; 3 First metal conductive assembly; 31 First connection point; 32 Connecting wire; 4 Second metal conductive assembly; 41 Second connection point. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] Flexible microelectrode arrays possess excellent flexibility and stretchability, enabling better adhesion to the nerve cell interface. This allows for long-term stable culture of neurons and real-time signal detection, while also improving the sensitivity and quality of neurophysiological signal detection. In neuroscience, flexible microelectrode arrays can be used to study brain function and nervous system diseases. By recording the electrical activity of different brain regions, their functional state and pathological changes can be understood. They can also be used in brain-computer interface research, facilitating direct communication between the human brain and computers or other devices.

[0055] Currently, flexible electrode structures used in the cerebral cortex are generally planar thin-film brain signal metal electrodes with a certain height. In the long-term implantation environment of the brain, there are problems such as large implantation wounds, great damage to the human body, and inability to achieve integrated implantation.

[0056] For example, a brain-computer interface with gel microneedle electrodes is disclosed, which includes multiple microneedle electrodes, each comprising multiple microneedles. Each microneedle includes a gel electrolyte and a cylindrical electrode. The microneedle electrode has a hollow, conical, biomimetic outer layer. The cylindrical electrode passes through the gel electrolyte and is exposed at the tip of the microneedle. The other side of the cylindrical electrode is connected to a metal film wire and is fully covered by an insulating layer. The electrodes are connected to a communication device via flexible wires. This disclosed brain-computer interface with gel microneedle electrodes has low impedance and can rapidly and accurately acquire EEG signals. However, the gel microneedle electrodes have a large area, resulting in a large implantation wound and significant damage to the human body, making integrated implantation impossible.

[0057] A microneedle array brain-computer interface device and its fabrication method are disclosed. The method involves using a non-conductive material as the inter-needle insulating layer, fabricating several through-holes in the insulating layer, fabricating several metal pads on a conductive material layer, placing the conductive material layer below the inter-needle insulating layer, and connecting the upper surface of the conductive material layer to the lower surface of the insulating layer, processing the conductive material layer into an array of micro-pillar structures with mutual insulation between them, processing the micro-pillar structures into microneedles with needle tips at the bottom, forming an array of microneedles with the needle tips pointing downwards, fabricating external leads for connecting to external circuits above the microneedle array layer, and fabricating electrode points on the needle tips of the microneedle array layer, thus obtaining the microneedle array brain-computer interface device. This invention has advantages such as reducing the number of process steps in the microneedle array brain-computer interface device, improving production efficiency and yield, and reducing the processing cost of the device. However, the silicon-based array electrode fabrication process is prone to brittle fracture during implantation, and the rigid substrate material can easily cause brain tissue damage. Furthermore, the flexible wires used to connect to subsequent devices make integrated implantation difficult.

[0058] In view of this, this application provides a flexible microelectrode array for brain-computer interfaces, a method for preparing the array, and a brain-computer interface device, to solve the problems of multiple encapsulation cycles, large implantation wounds, and significant damage to the human body.

[0059] Firstly, such as Figures 1 to 3As shown, this application provides a flexible microelectrode array 100 for a brain-computer interface, including a flexible substrate 1, a plurality of brain signal metal electrodes 2, a first metal conductive component 3, and a second metal conductive component 4. The flexible substrate 1 has a first side and a second side disposed opposite to each other. The plurality of brain signal metal electrodes 2 are disposed on the first side and spaced apart to form an electrode array. The first metal conductive component 3 is disposed on the second side of the flexible substrate 1 and encapsulated within the flexible substrate 1, including a plurality of first connection points 31 and a plurality of connecting wires 32. The second metal conductive component 4 includes a plurality of second connection points 41 exposed on the flexible substrate 1, the second connection points 41 being disposed on either the first or second side of the flexible substrate 1. The plurality of first connection points 31 are respectively connected to the plurality of brain signal metal electrodes 2, and simultaneously connected to the plurality of second connection points 41 via the plurality of connecting wires 32. The plurality of second connection points 41 are used for communication with a processor.

[0060] In this application, when the flexible microelectrode array 100 is implanted in the brain, the brain signal metal electrode 2 is in contact with the brain's nerves. The first metal conductive component 3 is connected to the brain signal metal electrode 2 and transmits the brain signal received by the brain signal metal electrode 2 to the second metal conductive component 4. The second metal conductive component 4 transmits the signal to the processor through the second connection point 41 to realize control or response. Since multiple first connection sites 31 are respectively connected to multiple brain signal metal electrodes 2, and are respectively connected to multiple second connection sites 41 through multiple connecting wires 32, and the multiple first connection sites 31 and multiple connecting wires 32 are encapsulated in the flexible substrate 1, there is no need to set additional leads to connect the first connection sites 31 and the second connection sites 41. The signal connection between the first connection sites 31 and the second connection sites 41 can be achieved directly through the patterned connecting wires 32. Since the second connection sites 41 are exposed, they can be directly soldered to the solder array of the processor. After soldering, only the processor and the electrode array need to be integrated into a single package to achieve the encapsulation and protection of the entire flexible microelectrode array 100, without the need for additional encapsulation of the leads connecting the first connection sites 31 and the second connection sites 41, and without the need to lead out the leads. This reduces the volume of the flexible microelectrode array 100, resulting in a smaller implantation wound and less damage to brain tissue.

[0061] It should be noted that there are two forms in which the second connection site 41 is located on the first or second side of the flexible substrate 1: one is that all the second connection sites 41 are located on the second side of the flexible substrate 1; the other is that all the second connection sites 41 are located on the first side of the flexible substrate 1.

[0062] The first metal conductive assembly 3 is encapsulated within the insulating layer 12 on the second side of the flexible substrate 1, which can fix and protect the electrode, reduce electrode movement, and reduce damage to brain tissue. The second metal conductive assembly 4 is exposed outside the insulating layer 12 on either the first or second side of the flexible substrate 1, and can be directly soldered to the processor's solder array without the need for additional leads to be drawn from the electrode array and secondary encapsulated. This achieves good signal conduction without complex wiring, large-area wiring, or large implantation wounds.

[0063] This application does not limit the shape of the flexible microelectrode array 100, which can be circular, square, triangular, rhomboid, or polygonal. It should be noted that in some embodiments, the brain signal metal electrode 2 can adopt a protruding tip electrode structure design, which improves the mechanical strength of the electrode, enhances the mechanical properties and ductility for long-term implantation, and meets the requirements for long-term implantation. The flexible tip electrode array is more easily adapted to the curved surface of the cerebral cortex, reducing displacement and slippage in the long-term implantation environment, resulting in more accurate signal transmission. To improve the biocompatibility of the flexible microelectrode array 100, multiple protrusions 11 with mounting channels can be provided on the first side of the flexible substrate 1. The brain signal metal electrode 2 is placed in the mounting channels of the protrusions 11, with the tip exposed. This increases the pressure on the tip during implantation, reduces implantation resistance, improves the accuracy of signal transmission, and reduces damage to brain tissue from rigid metal materials.

[0064] In conjunction with the first aspect, in some embodiments provided in this application, the second metal conductive component 4 is disposed on the periphery of the first metal conductive component 3. Since the first metal conductive component 3 is encapsulated within the insulating layer 12 on the second side of the flexible substrate 1 and is respectively connected to the plurality of brain signal metal electrodes 2, and the second metal conductive component 4 is exposed outside the insulating layer 12 on the second side of the flexible substrate 1 for connection to the processor, in order to reduce interference between the second metal conductive component 4 and the first metal conductive component 3, the second metal conductive component 4 is disposed on the periphery of the first metal conductive component 3, such that the first metal conductive component 3 is located in the middle and the second metal conductive component 4 is located at the edge. This also reduces the wiring distance of the second metal conductive component 4, facilitating connection to the processor.

[0065] In conjunction with the first aspect, in some embodiments provided in this application, the flexible substrate 1 is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone, which are biocompatible materials that reduce the risk of rejection reactions.

[0066] In conjunction with the first aspect, in some embodiments provided in this application, the material of the brain signal metal electrode 2 includes at least one of gold, silver, copper and platinum. The brain signal metal electrode 2 has good mechanical strength and ductility, meeting the requirements for long-term implantation. Using at least one of the above materials can improve the stability of the brain signal metal electrode 2 and reduce the harm to the human body caused by electrode corrosion.

[0067] In conjunction with the first aspect, in some embodiments provided in this application, the number of brain signal metal electrodes 2 is 8 to 64. The electrode array formed by 8 to 64 brain signal metal electrodes 2 is usually a low-throughput electrode array with less signal and lower transmission resistance. The integrated packaging can realize direct data transmission while reducing the transmission pressure caused by excessive data volume.

[0068] The shapes of the first connection point 31 and the second connection point 41 include, but are not limited to, square, circular, triangular, rhomboid, trapezoidal, or polygonal. The positions of the second connection points 41 can be equally spaced or non-equally spaced, and can be set only on one side of the flexible microelectrode array 100, or on opposite or adjacent sides, or around the perimeter.

[0069] It should be noted that the position and number of the first connection sites 31 correspond one-to-one with the brain signal metal electrodes 2, and the number of the second connection sites 41 corresponds to the number of the first connection sites 31. That is, each brain signal metal electrode 2 is connected to one first connection site 31, and each first connection site 31 is connected to one second connection site 41 through a connecting wire 32, thereby enabling the transmission of the signal of each brain signal metal electrode 2 to the processor. The signals of each electrode do not interfere with each other and are transmitted independently.

[0070] It should be noted that the thickness of the flexible substrate 1 can be 10–70 μm. The total height of the brain signal metal electrode 2 can be 0.5–2 mm, the exposed height can be 0.1–0.5 mm, and the diameter can be 0.1–1.5 mm. The shape of the protrusion 11 can be cylindrical or conical. To improve implantation efficiency and reduce implantation resistance, the protrusion 11 is usually conical.

[0071] Secondly, this application provides a method for fabricating a flexible microelectrode array, comprising the following steps:

[0072] A flexible substrate with multiple spaced protrusions on one side was fabricated.

[0073] A metal conductive layer containing multiple connection sites and connecting wires is fabricated on the side of the flexible substrate without protrusions;

[0074] A flexible substrate material is used to encapsulate the connection sites and connecting wires of a portion of the metal conductive layer to form multiple first connection sites and multiple connecting wires of a first metal conductive assembly. Another portion of the connection sites of the metal conductive layer is exposed to form multiple second connection sites of a second metal conductive assembly.

[0075] Brain signal metal electrode mounting channels are formed on the protrusions of a flexible substrate. Brain signal metal electrodes are fabricated within the mounting channels and connected to a first metal conductive component to obtain a flexible microelectrode array.

[0076] By fabricating a metal conductive layer containing multiple connection sites and connecting wires on the protrusion-free side of a flexible substrate, and encapsulating part of the connection sites of the metal conductive layer with an insulating material to form a first metal conductive component, while exposing the other part of the connection sites of the metal conductive layer to form a second metal conductive component, reliable communication between the first and second metal conductive components can be achieved. Both metal conductive components can be formed in a single molding process. Furthermore, by forming brain signal metal electrode mounting channels on the protrusions of the flexible substrate, and fabricating brain signal metal electrodes within these channels, which are then connected to the first metal conductive component, a flexible microelectrode array is obtained. This allows for customization of the number and size of electrodes according to specific application requirements, and the design of electrode shapes suitable for different brain regions, offering greater flexibility and versatility. By patterning during the fabrication of the metal conductive layer, multiple first connection points and multiple connecting wires of the first metal conductive component, as well as multiple second connection points of the second metal conductive component, can be formed in one step. By encapsulating the multiple first connection points and multiple connecting wires with a flexible substrate material, a reliable connection between the first connection points and the second connection points can be achieved. There is no need to lead out additional leads from the first connection points, nor is there a need to encapsulate the leads. The structure is simple, and the data transmission is direct and accurate.

[0077] Insulating layer materials include, but are not limited to, flexible materials with good biocompatibility such as PDMS (polydimethylsiloxane), PMMA (polymethyl methacrylate), PI (polyimide), Parylene-C (para-xylene polymer), and silicone. Using the same material as the flexible substrate can further improve flexibility and biocompatibility. Methods for forming the insulating layer include, but are not limited to, thin film deposition processes (CVD, PVD), spin coating processes, stencil casting processes, and electrochemical deposition processes.

[0078] In conjunction with the second aspect, in some embodiments provided in this application, the fabrication of a flexible substrate having a plurality of spaced protrusions on one side includes:

[0079] A flexible mold layer is fabricated on a substrate;

[0080] Multiple spaced tapered holes are cut into the flexible mold layer;

[0081] A flexible substrate with multiple spaced protrusions is prepared on the side of the flexible mold layer containing a tapered hole.

[0082] By cutting multiple spaced-apart tapered holes in a flexible mold layer, a flexible substrate with multiple spaced-apart protrusions is prepared on the side of the flexible mold layer containing the tapered holes. This method allows for the fabrication of a flexible substrate with multiple spaced-apart protrusions using a mold, and the shape of the flexible substrate can be changed by altering the shape of the mold, offering greater flexibility and simplicity. Subsequently, the flexible mold layer and substrate can be removed by demolding. The substrate can be a rigid material, including but not limited to silicon wafers and quartz sheets, which improves the support strength of the flexible substrate during fabrication and reduces deformation. The flexible substrate with multiple spaced-apart protrusions can be fabricated using thin-film deposition processes (CVD, PVD), template casting processes, and electrochemical deposition processes.

[0083] In conjunction with the second aspect, in some embodiments provided in this application, the fabrication of a metal conductive layer containing multiple connection sites and connecting wires on the side of the flexible substrate without protrusions includes:

[0084] Photoresist was spin-coated onto a flexible substrate to obtain a photoresist mask;

[0085] A metal layer is prepared under the cover of a photoresist mask, and the photoresist is removed to obtain a metal conductive layer containing multiple connection sites and connecting wires.

[0086] Since the metal conductive layer is not a flat plane, but rather forms different conductive layer patterns based on the positions of the brain signal metal electrodes and the wires connecting multiple brain signal metal electrodes, to prepare a metal conductive layer with a specific pattern, a photoresist mask is used. After preparing the metal layer, the photoresist is removed, resulting in a metal conductive layer containing multiple connection sites and connecting wires. The photoresist can be either positive or negative; positive photoresist cures under light, while negative photoresist dissolves under light. Methods for preparing the metal layer include, but are not limited to, thin film deposition processes (CVD, PVD, evaporation), template casting processes, electrochemical deposition processes, electroplating processes, and machining processes.

[0087] In conjunction with the second aspect, in some embodiments provided in this application, the method of forming a brain signal metal electrode mounting channel on the protrusion of the flexible substrate, fabricating a brain signal metal electrode within the mounting channel, and connecting it to a first metal conductive component to obtain a flexible microelectrode array: the method of forming the brain signal metal electrode mounting channel includes laser cutting or dry etching. By forming the brain signal metal electrode mounting channel through laser cutting or dry etching of the flexible mold layer, the number, shape, and position of the brain signal metal electrodes can be better controlled.

[0088] In conjunction with the second aspect, in some embodiments provided in this application, the brain signal metal electrode mounting channel is formed on the protrusion of the flexible substrate, and a brain signal metal electrode is prepared in the mounting channel and connected to the first metal conductive component to obtain a flexible microelectrode array. The method for preparing the brain signal metal electrode includes any one of electrochemical deposition, capillary effect and metal welding. By using electrochemical deposition, capillary effect and metal welding to prepare the brain signal metal electrode, the amount of metal electrode prepared can be controlled to achieve the expected effect.

[0089] In conjunction with the second aspect, in some embodiments provided in this application, the flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone, which are biocompatible materials that reduce the risk of rejection reactions.

[0090] In conjunction with the second aspect, in some embodiments provided in this application, the material of the brain signal metal electrode includes at least one of gold, silver, copper and platinum. The brain signal metal electrode has good mechanical strength and ductility, meeting the requirements for long-term implantation. Using at least one of the above materials can improve the stability of the brain signal metal electrode and reduce the harm to the human body caused by electrode corrosion.

[0091] In some embodiments of this application, such as Figure 4 As shown, the specific steps for fabricating a flexible microelectrode array can be as follows:

[0092] S10. Spin-coat a flexible material onto a substrate to obtain a flexible mold;

[0093] S20. A tapered hole structure is prepared on a flexible mold by laser etching, but not limited to this process;

[0094] S30. Spin-coating a flexible material onto a flexible mold to obtain a flexible substrate layer;

[0095] S40. Deposit a wire metal layer on a flexible substrate using a PVD process;

[0096] S50. Spin-coat photoresist onto the surface of the metal layer. The photoresist type can be either positive or negative.

[0097] S60. The photoresist layer is exposed using a photolithography machine, and the surface of the photoresist layer is developed to reveal the area of ​​the conductor metal layer that needs to be etched.

[0098] S70. The exposed metal layer area is etched using an etching process to form a metal wire pattern;

[0099] S80. Remove all photoresist from the surface (dry etching or wet etching);

[0100] S90. Spin-coat an insulating layer material onto the metal wire pattern to wrap the metal wire;

[0101] S100. Spin-coat photoresist onto the surface of the insulating layer material. The photoresist type can be positive or negative.

[0102] S110. The photoresist is exposed by a photolithography machine, and the surface of the photoresist is developed to reveal the insulating layer area that needs to be etched.

[0103] S120. The area to be etched in the insulating layer is etched by dry etching to form a metal wire window;

[0104] S130, Remove all photoresist from the surface;

[0105] S140. Spin-coat a release photoresist onto the surface of the insulating layer material. The photoresist type can be positive or negative.

[0106] S150. The photoresist is exposed by a photolithography machine, and the surface of the photoresist is developed to reveal the metal wire window that needs to be etched.

[0107] S160. Metal contacts are deposited in the metal wire window using a PVD process to form multiple second connection sites;

[0108] S170, Remove the surface stripping photoresist through a stripping process;

[0109] S180. Separate the flexible mold layer from the flexible substrate layer to obtain a flexible substrate with a protruding tip structure;

[0110] S190, flip-type flexible substrate;

[0111] S200. Spin-coat photoresist onto one side of the tip structure of the flexible substrate. The photoresist type can be positive or negative.

[0112] S210. The photoresist is exposed by a photolithography machine, and the surface of the photoresist is developed to reveal the metal tip window that needs to be etched.

[0113] S220. Etching the protruding tip structure to prepare a through-hole structure, the etching method including but not limited to laser etching and dry etching;

[0114] S230, Remove all photoresist;

[0115] S240. Conductive metal materials are prepared in a through-hole structure to obtain a metal tip structure, i.e., a metal electrode. The preparation methods include, but are not limited to, electrochemical deposition, metal welding, siphoning and other methods.

[0116] in Figure 4 (a) is a process flow diagram for steps S10 to S40. Figure 4(b) is a process flow diagram for steps S50 to S80. Figure 4 (c) is a process flow diagram for steps S90 to S120. Figure 4 (d) is a process flow diagram for steps S130 to S160. Figure 4 (e) is a process flow diagram for steps S170 to S200. Figure 4 (f) is a process flow diagram of steps S210 to S240.

[0117] Thirdly, this application proposes a brain-computer interface device, including the flexible microelectrode array of the first aspect of this application.

[0118] In summary, when the flexible microelectrode array is implanted in the brain, the brain signal metal electrodes make contact with the brain's nerves. The first metal connecting component, connected to the brain signal metal electrodes, transmits the brain signals received by the brain signal metal electrodes to the second metal connecting component. The second metal connecting component then transmits the signals to the processor through connection points to achieve control or response. Since multiple first connection points are connected to multiple brain signal metal electrodes respectively, and simultaneously connected to multiple second connection points respectively through multiple connecting wires, and these multiple first connection points and multiple connecting wires are encapsulated within a flexible substrate, there is no need to additionally set up leads connecting the first and second connection points. The signal connection between the first and second connection points is directly achieved through patterned connecting wires. Furthermore, since the second connection points are exposed, they can be directly soldered to the processor's solder pad array. After soldering, only an integrated encapsulation of the processor and electrode array is needed to achieve the encapsulation and protection of the entire flexible microelectrode array, eliminating the need for additional encapsulation of the leads connecting the first and second connection points, and eliminating the need to expose the leads. This reduces the volume of the flexible microelectrode array, resulting in a smaller implantation wound and less damage to brain tissue.

[0119] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0120] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A flexible microelectrode array for brain-computer interfaces, characterized in that, include: A flexible substrate having a first side and a second side disposed opposite to each other; Multiple brain signal metal electrodes are disposed on the first side and spaced apart to form an electrode array; A first metal conductive assembly is disposed on the second side of the flexible substrate and encapsulated within the flexible substrate, including multiple first connection points and multiple connecting wires; as well as, The second metal conductive assembly includes a plurality of second connection sites exposed on the flexible substrate, the second connection sites being disposed on a second side of the flexible substrate, and the second metal conductive assembly being disposed on the periphery of the first metal conductive assembly; The plurality of first connection sites are respectively connected to the plurality of brain signal metal electrodes, and are also respectively connected to the plurality of second connection sites through the plurality of connecting wires; Multiple second connection points are used for communication connections with the processor; Through-hole structures are prepared by etching the protrusion tip structure, so that multiple protrusions with mounting channels are provided on the first side of the flexible substrate; Conductive metal materials are prepared in a through-hole structure to obtain a metal tip structure, i.e., a metal electrode, which enables the placement of brain signal metal electrodes in the protrusion containing the mounting channel, with the tip exposed.

2. The flexible microelectrode array for brain-computer interfaces as described in claim 1, characterized in that, The flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone.

3. The flexible microelectrode array for brain-computer interfaces as described in claim 1, characterized in that... The material of the brain signal metal electrode includes at least one of gold, silver, copper and platinum.

4. The flexible microelectrode array for brain-computer interfaces as described in claim 1, characterized in that... The flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone. The material of the brain signal metal electrode includes at least one of gold, silver, copper, and platinum.

5. The flexible microelectrode array for brain-computer interfaces as described in claim 1, characterized in that, The number of brain signal metal electrodes is 8 to 64.

6. A method for fabricating a flexible microelectrode array for brain-computer interfaces, characterized in that, Includes the following steps: A flexible substrate with multiple spaced protrusions on one side was fabricated. A metal conductive layer containing multiple connection sites and connecting wires is fabricated on the side of the flexible substrate without protrusions; A flexible substrate material is used to encapsulate the connection sites and connecting wires of a portion of the metal conductive layer to form multiple first connection sites and multiple connecting wires of a first metal conductive assembly. Another portion of the connection sites of the metal conductive layer is exposed to form multiple second connection sites of a second metal conductive assembly. The second metal conductive assembly is disposed on the periphery of the first metal conductive assembly. Brain signal metal electrode mounting channels are formed on the protrusions of a flexible substrate, brain signal metal electrodes are fabricated in the mounting channels, and connected to a first metal conductive component to obtain a flexible microelectrode array. Among them, multiple first connection sites are respectively connected to multiple brain signal metal electrodes, and are also respectively connected to multiple second connection sites through multiple connecting wires; Through-hole structures are prepared by etching the protruding tip structure; Conductive metal materials are prepared in a through-hole structure to obtain a metal tip structure, i.e., a metal electrode.

7. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The process of fabricating a flexible substrate with multiple spaced protrusions on one side includes: A flexible mold layer is fabricated on a substrate; Multiple spaced tapered holes are cut into the flexible mold layer; A flexible substrate with multiple spaced protrusions is prepared on the side of the flexible mold layer containing a tapered hole.

8. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The fabrication of a metal conductive layer containing multiple connection sites and connecting wires on the non-protruding side of the flexible substrate includes: Photoresist was spin-coated onto a flexible substrate to obtain a photoresist mask; A metal layer is prepared under the cover of a photoresist mask, and the photoresist is removed to obtain a metal conductive layer containing multiple connection sites and connecting wires.

9. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The process involves forming brain signal metal electrode mounting channels on the protrusions of a flexible substrate, fabricating brain signal metal electrodes within these channels, and connecting them to a first metal conductive component to obtain a flexible microelectrode array. Methods for creating channels for mounting metal electrodes for brain signals include laser cutting or dry etching.

10. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, Methods for preparing brain signal metal electrodes include any one of electrochemical deposition, capillary effect, and metal welding.

11. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The process involves forming brain signal metal electrode mounting channels on the protrusions of a flexible substrate, fabricating brain signal metal electrodes within these channels, and connecting them to a first metal conductive component to obtain a flexible microelectrode array. Methods for forming channels for mounting metal electrodes for brain signals include laser cutting or dry etching; Methods for preparing brain signal metal electrodes include any one of electrochemical deposition, capillary effect, and metal welding.

12. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone.

13. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The material of the brain signal metal electrode includes at least one of gold, silver, copper, and platinum.

14. The method for fabricating a flexible microelectrode array for brain-computer interfaces as described in claim 6, characterized in that, The flexible substrate is made of at least one of polydimethylsiloxane, polymethyl methacrylate, polyimide, p-xylene polymer, and silicone. The material of the brain signal metal electrode includes at least one of gold, silver, copper, and platinum.

15. A brain-computer interface device, characterized in that, Includes the flexible microelectrode array for brain-computer interfaces as described in any one of claims 1 to 5.

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