Brain-computer interface(BCI)is an advanced technology that establishes a direct connection between the brain and external devices,enabling high-speed and real-time information exchange.In BCI systems,electrodes are k...Brain-computer interface(BCI)is an advanced technology that establishes a direct connection between the brain and external devices,enabling high-speed and real-time information exchange.In BCI systems,electrodes are key interface devices responsible for transmitting signals between the brain and external devices,including recording electrophysiological signals and electrically stimulating nerves.Early BCI electrodes were mainly composed of rigid materials.The mismatch in Young's modulus between rigid electrodes and soft biological tissue can lead to rejection reactions within the biological system,resulting in electrode failure.Furthermore,rigid electrodes are prone to damaging biological tissues during implantation and use.Recently,flexible electrodes have garnered attention in the field of brain science research due to their better adaptability to the softness and curvature of the brain.The design of flexible electrodes can effectively reduce mechanical damage to neural tissue and improve the accuracy and stability of signal transmission,providing new tools and methods for exploring brain function mechanisms and developing novel neural interface technologies.Here,we review the research advancements in neural electrodes for BCI systems.This paper emphasizes the importance of neural electrodes in BCI systems,discusses the limitations of traditional rigid neural electrodes,and introduces various types of flexible neural electrodes in detail.In addition,we also explore practical application scenarios and future development trends of BCI electrode technology,aiming to offer valuable insights for enhancing the performance and user experience of BCI systems.展开更多
The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—par...The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.展开更多
Flexible implantable electrodes provide unprecedented opportunities for gentle mechanical interaction with soft neural tissues to acquire stable electrophysiological signals and reduce risk of tissue inflammatory resp...Flexible implantable electrodes provide unprecedented opportunities for gentle mechanical interaction with soft neural tissues to acquire stable electrophysiological signals and reduce risk of tissue inflammatory response.Most electrocorticography(ECoG)electrodes adopt polymer film or silicone as substrate,with thickness sacrifice or poor micromachining precision,respectively.Besides,the distance of recessed electrode site to cortical surface leads to signal degradation.Here,we report a 3D polyimide-based electrode array on soft microbumps(height,327µm),with buffering contact capability and reliable mechanical strength that alleviates the mismatch from dental cement or cranial window.We demonstrate the reshaping processes of conventional 2D sites(diameter,200µm)into 3D protruding structure by stress-free preforming and silicone casting.The 3D soft microbump electrodes(SMBE)remain well undergoing whether cyclic voltammetry scanning or cyclic compression.The acute implanted SMBE array has shown sensitive response to whisker pulling and insusceptible stability by external force of anesthetic rats.展开更多
Increasing the proximity of microelectrode arrays(MEA)to targeted neural tissues can establish efficient neural interfaces for both recording and stimulation applications.This has been achieved by constructing protrud...Increasing the proximity of microelectrode arrays(MEA)to targeted neural tissues can establish efficient neural interfaces for both recording and stimulation applications.This has been achieved by constructing protruding three-dimensional(3D)structures on top of conventional planar microelectrodes via additional micromachining steps.However,this approach adds fabrication complexities and limits the 3D structures to certain shapes.We propose a one-step fabrication of MEAs with versatile microscopic 3D structures via“microelectrothermoforming(μETF)”of thermoplastics,by utilizing 3D-printed molds to locally deform planar MEAs into protruding and recessing shapes.Electromechanical optimization enabled a 3D MEA with 80μm protrusions and/or recession for 100μm diameter.Its simple and versatile shaping capabilities are demonstrated by diverse 3D structures on a single MEA.The benefits of 3D MEA are evaluated in retinal stimulation through numerical simulations and ex vivo experiments,confirming a threshold lowered by 1.7 times and spatial resolution enhanced by 2.2 times.展开更多
Transparent electro-optical neural interfacing technologies offer simultaneous high-spatial-resolution microscopic imaging,and high-temporal-resolution electrical recording and stimulation.However,fabricating transpar...Transparent electro-optical neural interfacing technologies offer simultaneous high-spatial-resolution microscopic imaging,and high-temporal-resolution electrical recording and stimulation.However,fabricating transparent,flexible,and mechanically robust neural electrodes with high electrochemical performance remains challenging.In this study,we fabricated transparent(72.7%at 570 nm),mechanically robust(0.05%resistance change after 50k bending cycles)ultrathin Au microelectrodes for micro-electrocorticography(µECoG)using a hexadentate metal-polymer ligand bonding with an EDTA/PSS seed layer.These transparentµECoG arrays,fabricated with biocompatible gold,exhibit excellent electrochemical properties(0.73Ω·cm^(2))for neural recording and stimulation with long-term stability.We recorded brain surface waves in vivo,maintaining a low baseline noise and a high signalto-noise ratio during acute and two-week recordings.In addition,we successfully performed optogenetic modulation without light-induced artifacts at 7.32 mW/mm^(2)laser power density.This approach shows great potential for scalable,implantable neural electrodes and wearable optoelectronic devices in digital healthcare systems.展开更多
The neural interface is a key component in wireless brain–computer prostheses.In this study,we demonstrate that a unique three-dimensional(3D)microneedle electrode on a flexible mesh substrate,which can be fabricated...The neural interface is a key component in wireless brain–computer prostheses.In this study,we demonstrate that a unique three-dimensional(3D)microneedle electrode on a flexible mesh substrate,which can be fabricated without complicated micromachining techniques,is conformal to the tissues with minimal invasiveness.Furthermore,we demonstrate that it can be applied to different functional layers in the nervous system without length limitation.The microneedle electrode is fabricated using drawing lithography technology from biocompatible materials.In this approach,the profile of a 3D microneedle electrode array is determined by the design of a two-dimensional(2D)pattern on the mask,which can be used to access different functional layers in different locations of the brain.Due to the sufficient stiffness of the electrode and the excellent flexibility of the mesh substrate,the electrode can penetrate into the tissue with its bottom layer fully conformal to the curved brain surface.Then,the exposed contact at the end of the microneedle electrode can successfully acquire neural signals from the brain.展开更多
Implantable neural electrodes are key components of brain-computer interfaces(BCI),but the mismatch in mechanical and biological properties between electrode materials and brain tissue can lead to foreign body reactio...Implantable neural electrodes are key components of brain-computer interfaces(BCI),but the mismatch in mechanical and biological properties between electrode materials and brain tissue can lead to foreign body reactions and glial scarring,and subsequently compromise the long-term stability of electrical signal transmission.In this study,we proposed a new concept for the design and bioaugmentation of implantable electrodes(bio-array electrodes)featuring a heterogeneous gradient structure.Different composite polyaniline-gelatin-alginate based conductive hydrogel formulations were developed for electrode surface coating.In addition,the design,materials,and performance of the developed electrode was optimized through a combination of numerical simulations and physio-chemical characterizations.The long-term biological performance of the bio-array electrodes were investigated in vivo using a C57 mouse model.It was found that compared to metal array electrodes,the surface charge of the bio-array electrodes increased by 1.74 times,and the impedance at 1 kHz decreased by 63.17%,with a doubling of the average capacitance.Long-term animal experiments showed that the bio-array electrodes could consistently record 2.5 times more signals than those of the metal array electrodes,and the signal-to-noise ratio based on action potentials was 2.1 times higher.The study investigated the mechanisms of suppressing the scarring effect by the bioaugmented design,revealing reduces brain damage as a result of the interface biocompatibility between the bio-array electrodes and brain tissue,and confirmed the long-term in vivo stability of the bio-array electrodes.展开更多
This study explores the history and current state of Brain-Computer Interfaces(BCIs),focusing on non-invasive,EEG-based devices.BCIs have evolved from early studies in neurophysiology to real-world applications that c...This study explores the history and current state of Brain-Computer Interfaces(BCIs),focusing on non-invasive,EEG-based devices.BCIs have evolved from early studies in neurophysiology to real-world applications that convert brain impulses into executable commands.The study discusses the two main categories of BCIs:invasive and non-invasive,highlighting their benefits and limitations.Invasive BCIs provide precise signals but carry higher risks and ethical concerns,while non-invasive BCIs are safer but face challenges with signal deterioration and external noise.The study also evaluates the potential of wider use and availability of non-invasive interfaces by analysing their existing capabilities,limits,and potential future developments.Solutions to overcome technological and ethical challenges are explored to improve usability,user experience,and impact in areas such as healthcare,rehabilitation,entertainment,and cognitive enhancement.展开更多
The creation of biomimetic neuron interfaces(BNIs)has become imperative for different research fields from neural science to artificial intelligence.BNIs are two-dimensional or three-dimensional(3D)artificial interfac...The creation of biomimetic neuron interfaces(BNIs)has become imperative for different research fields from neural science to artificial intelligence.BNIs are two-dimensional or three-dimensional(3D)artificial interfaces mimicking the geometrical and functional characteristics of biological neural networks to rebuild,understand,and improve neuronal functions.The study of BNI holds the key for curing neuron disorder diseases and creating innovative artificial neural networks(ANNs).To achieve these goals,3D direct laser writing(DLW)has proven to be a powerful method for BNI with complex geometries.However,the need for scaled-up,high speed fabrication of BNI demands the integration of DLW techniques with ANNs.ANNs,computing algorithms inspired by biological neurons,have shown their unprecedented ability to improve efficiency in data processing.The integration of ANNs and DLW techniques promises an innovative pathway for efficient fabrication of large-scale BNI and can also inspire the design and optimization of novel BNI for ANNs.This perspective reviews advances in DLW of BNI and discusses the role of ANNs in the design and fabrication of BNI.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:52173237,52473255:Fundamental Research Funds for the Central Universities,Grant/Award Numbers:HIT.NSRIF 202315,HIT.OCEF.2022018Natural Science Foundation of Heilongjiang Province,Grant/Award Numbers:LH2021B009,LH2022E051+1 种基金Interdisciplinary Research Foundation of HIT,Grant/Award Number:IR2021207Open Project Program of Key Laboratory for Photonic and Electric Bandgap Materials,Grant/Award Number:PEBM202107。
文摘Brain-computer interface(BCI)is an advanced technology that establishes a direct connection between the brain and external devices,enabling high-speed and real-time information exchange.In BCI systems,electrodes are key interface devices responsible for transmitting signals between the brain and external devices,including recording electrophysiological signals and electrically stimulating nerves.Early BCI electrodes were mainly composed of rigid materials.The mismatch in Young's modulus between rigid electrodes and soft biological tissue can lead to rejection reactions within the biological system,resulting in electrode failure.Furthermore,rigid electrodes are prone to damaging biological tissues during implantation and use.Recently,flexible electrodes have garnered attention in the field of brain science research due to their better adaptability to the softness and curvature of the brain.The design of flexible electrodes can effectively reduce mechanical damage to neural tissue and improve the accuracy and stability of signal transmission,providing new tools and methods for exploring brain function mechanisms and developing novel neural interface technologies.Here,we review the research advancements in neural electrodes for BCI systems.This paper emphasizes the importance of neural electrodes in BCI systems,discusses the limitations of traditional rigid neural electrodes,and introduces various types of flexible neural electrodes in detail.In addition,we also explore practical application scenarios and future development trends of BCI electrode technology,aiming to offer valuable insights for enhancing the performance and user experience of BCI systems.
文摘The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.
基金support received from the Science and Technology Innovation 2030-Major Project(2022ZD0208601,2022ZD0208600)National Natural Science Foundation of China(62204204,62104056)+2 种基金Innovation Capability Support Program of Shaanxi(2024RSCXTD-7)NaturalScience Basic Research Plan in Shaanxi Province of China(2023JC-XJ-07)support from Dr.Honglai Xu,Mr.Yuxiang Hong from Neuracle Medical Technology(Shanghai)Co.,Ltd.,Mr.Xiaowang Zhao from LPKF Shanghai Co.,Ltd.,staffs from Wenzhou Institute of Hangzhou Dianzi University and Xi'an LEADMEMS SCI&-TECH Co.,Ltd。
文摘Flexible implantable electrodes provide unprecedented opportunities for gentle mechanical interaction with soft neural tissues to acquire stable electrophysiological signals and reduce risk of tissue inflammatory response.Most electrocorticography(ECoG)electrodes adopt polymer film or silicone as substrate,with thickness sacrifice or poor micromachining precision,respectively.Besides,the distance of recessed electrode site to cortical surface leads to signal degradation.Here,we report a 3D polyimide-based electrode array on soft microbumps(height,327µm),with buffering contact capability and reliable mechanical strength that alleviates the mismatch from dental cement or cranial window.We demonstrate the reshaping processes of conventional 2D sites(diameter,200µm)into 3D protruding structure by stress-free preforming and silicone casting.The 3D soft microbump electrodes(SMBE)remain well undergoing whether cyclic voltammetry scanning or cyclic compression.The acute implanted SMBE array has shown sensitive response to whisker pulling and insusceptible stability by external force of anesthetic rats.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(NRF-2022R1C1C1010422,RS-2023-00217893,and NRF 2020R1C1C1010505)。
文摘Increasing the proximity of microelectrode arrays(MEA)to targeted neural tissues can establish efficient neural interfaces for both recording and stimulation applications.This has been achieved by constructing protruding three-dimensional(3D)structures on top of conventional planar microelectrodes via additional micromachining steps.However,this approach adds fabrication complexities and limits the 3D structures to certain shapes.We propose a one-step fabrication of MEAs with versatile microscopic 3D structures via“microelectrothermoforming(μETF)”of thermoplastics,by utilizing 3D-printed molds to locally deform planar MEAs into protruding and recessing shapes.Electromechanical optimization enabled a 3D MEA with 80μm protrusions and/or recession for 100μm diameter.Its simple and versatile shaping capabilities are demonstrated by diverse 3D structures on a single MEA.The benefits of 3D MEA are evaluated in retinal stimulation through numerical simulations and ex vivo experiments,confirming a threshold lowered by 1.7 times and spatial resolution enhanced by 2.2 times.
基金supported in part by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2022-NR069917,RS-2024-00416319)in part by the‘DGIST intramural grant’(25-IRJoint-03)+1 种基金in part by an Ideas Grant from the National Health and Medical Research Council(NHMRC)of Australia(APP1188414)in part by the Interdisciplinary Research Initiatives Program from College of Engineering and College of Medicine,Seoul National University(grant no.800-20240490).
文摘Transparent electro-optical neural interfacing technologies offer simultaneous high-spatial-resolution microscopic imaging,and high-temporal-resolution electrical recording and stimulation.However,fabricating transparent,flexible,and mechanically robust neural electrodes with high electrochemical performance remains challenging.In this study,we fabricated transparent(72.7%at 570 nm),mechanically robust(0.05%resistance change after 50k bending cycles)ultrathin Au microelectrodes for micro-electrocorticography(µECoG)using a hexadentate metal-polymer ligand bonding with an EDTA/PSS seed layer.These transparentµECoG arrays,fabricated with biocompatible gold,exhibit excellent electrochemical properties(0.73Ω·cm^(2))for neural recording and stimulation with long-term stability.We recorded brain surface waves in vivo,maintaining a low baseline noise and a high signalto-noise ratio during acute and two-week recordings.In addition,we successfully performed optogenetic modulation without light-induced artifacts at 7.32 mW/mm^(2)laser power density.This approach shows great potential for scalable,implantable neural electrodes and wearable optoelectronic devices in digital healthcare systems.
基金This work was supported by grants from the National Research Foundation(NRF)CRP project‘Peripheral Nerve Prostheses:A Paradigm Shift in Restoring Dexterous Limb Function’(NRF-CRP10-2012-01,R-719-000-001-281)the NRF CRP project‘Self-Powered Body Sensor Network for Disease Management and Prevention Oriented Healthcare’(NRF-CRP8-2011-01,R-263-000-A27-281).
文摘The neural interface is a key component in wireless brain–computer prostheses.In this study,we demonstrate that a unique three-dimensional(3D)microneedle electrode on a flexible mesh substrate,which can be fabricated without complicated micromachining techniques,is conformal to the tissues with minimal invasiveness.Furthermore,we demonstrate that it can be applied to different functional layers in the nervous system without length limitation.The microneedle electrode is fabricated using drawing lithography technology from biocompatible materials.In this approach,the profile of a 3D microneedle electrode array is determined by the design of a two-dimensional(2D)pattern on the mask,which can be used to access different functional layers in different locations of the brain.Due to the sufficient stiffness of the electrode and the excellent flexibility of the mesh substrate,the electrode can penetrate into the tissue with its bottom layer fully conformal to the curved brain surface.Then,the exposed contact at the end of the microneedle electrode can successfully acquire neural signals from the brain.
基金supported by the Program of the National Natural Science Foundation of China[52275291],[52435006]the Program for Innovation Team of Shaanxi Province(2023-CX-TD-17)the Fundamental Research Funds for the Central Universities.
文摘Implantable neural electrodes are key components of brain-computer interfaces(BCI),but the mismatch in mechanical and biological properties between electrode materials and brain tissue can lead to foreign body reactions and glial scarring,and subsequently compromise the long-term stability of electrical signal transmission.In this study,we proposed a new concept for the design and bioaugmentation of implantable electrodes(bio-array electrodes)featuring a heterogeneous gradient structure.Different composite polyaniline-gelatin-alginate based conductive hydrogel formulations were developed for electrode surface coating.In addition,the design,materials,and performance of the developed electrode was optimized through a combination of numerical simulations and physio-chemical characterizations.The long-term biological performance of the bio-array electrodes were investigated in vivo using a C57 mouse model.It was found that compared to metal array electrodes,the surface charge of the bio-array electrodes increased by 1.74 times,and the impedance at 1 kHz decreased by 63.17%,with a doubling of the average capacitance.Long-term animal experiments showed that the bio-array electrodes could consistently record 2.5 times more signals than those of the metal array electrodes,and the signal-to-noise ratio based on action potentials was 2.1 times higher.The study investigated the mechanisms of suppressing the scarring effect by the bioaugmented design,revealing reduces brain damage as a result of the interface biocompatibility between the bio-array electrodes and brain tissue,and confirmed the long-term in vivo stability of the bio-array electrodes.
文摘This study explores the history and current state of Brain-Computer Interfaces(BCIs),focusing on non-invasive,EEG-based devices.BCIs have evolved from early studies in neurophysiology to real-world applications that convert brain impulses into executable commands.The study discusses the two main categories of BCIs:invasive and non-invasive,highlighting their benefits and limitations.Invasive BCIs provide precise signals but carry higher risks and ethical concerns,while non-invasive BCIs are safer but face challenges with signal deterioration and external noise.The study also evaluates the potential of wider use and availability of non-invasive interfaces by analysing their existing capabilities,limits,and potential future developments.Solutions to overcome technological and ethical challenges are explored to improve usability,user experience,and impact in areas such as healthcare,rehabilitation,entertainment,and cognitive enhancement.
基金the support from the Science and Technology Commission of Shanghai Municipality(Grant No.21DZ1100500)the Shanghai Municipal Science and Technology Major Project,the Shanghai Frontiers Science Center Program(2021-2025 No.20)+2 种基金the Zhangjiang National Innovation Demonstration Zone(Grant No.ZJ2019-ZD-005)the National Key Research and Development Program of China(Grant No.2021YFB2802000)the National Natural Science Foundation of China(Grant No.61975123).
文摘The creation of biomimetic neuron interfaces(BNIs)has become imperative for different research fields from neural science to artificial intelligence.BNIs are two-dimensional or three-dimensional(3D)artificial interfaces mimicking the geometrical and functional characteristics of biological neural networks to rebuild,understand,and improve neuronal functions.The study of BNI holds the key for curing neuron disorder diseases and creating innovative artificial neural networks(ANNs).To achieve these goals,3D direct laser writing(DLW)has proven to be a powerful method for BNI with complex geometries.However,the need for scaled-up,high speed fabrication of BNI demands the integration of DLW techniques with ANNs.ANNs,computing algorithms inspired by biological neurons,have shown their unprecedented ability to improve efficiency in data processing.The integration of ANNs and DLW techniques promises an innovative pathway for efficient fabrication of large-scale BNI and can also inspire the design and optimization of novel BNI for ANNs.This perspective reviews advances in DLW of BNI and discusses the role of ANNs in the design and fabrication of BNI.
