闭环植入式神经刺激器的现状与发展趋势

闭环植入式神经刺激器能根据患者生理信号的变化自适应地调整刺激参数的特性,使其成为研究的热点,患者的临床需求推动其设计开发的进展。介绍3种闭环植入式神经刺激器的作用机制和刺激参数评估的理论研究以及临床应用现状,这3种闭环植入式神经刺激器分别为代表中枢神经、外周神经及脊髓神经的脑刺激器,迷走神经刺激器以及脊髓神经刺激器。概括分析闭环植入式神经刺激器研究应用中未解决的问题和发展趋势,即闭环植入式神经刺激器的作用机制仍需要深入研究,刺激参数评估的有效性需要进一步提高,应用于临床的系统有待继续完善。     

视觉假体神经刺激器的发展现状和挑战

老年黄斑变性(AMD)和视网膜色素变性(RP)是不可治愈性视网膜疾病致盲的主要原因。针对这两种致盲疾病,研发视觉假体使盲人重见光明已经成为当前科学领域的研究热点之一。而视觉假体刺激器作为视觉假体的关键模块,对传导人工视觉编码信息、获取有效的视觉诱发具有重要的作用。本文首先介绍了多个国际知名视觉假体神经刺激器的设计方案,分析了它们的优缺点。在此基础上,我们着重论述了视觉假体神经刺激器所面临的挑战及未来的发展趋势,包括视觉假体神经刺激器的灵活性设计、低功耗设计和无线数据和能量传输设计。     

基于光遗传学技术的脑机接口研究进展

脑机接口作为一种大脑和外部设备之间的双向通信系统,在增强脑功能、人机交互和神经康复方面得到了广泛应用。基于光遗传学技术的脑机接口,弥补了电极刺激在生物兼容性、刺激精度与细胞类型特异性上的缺陷,成为神经工程领域的研究热点。综述了光遗传学脑机接口在动物实验中的应用,以及在闭环调控脑区活动、反馈虚拟感觉和脑-脑交互等方面取得的研究进展;介绍了集成化和微型化新型光遗传学接口的研究前沿;总结了光遗传学脑机接口面临的挑战,以及探讨在多模态脑活动监测和脑-机智能等方向的发展前景。     

直接神经接口与控制技术

近年来逐渐成为热点的脑-机接口是一种不依靠外周神经和肌肉组织等通常的大脑输入／输出通道的通信与控制系统。直接神经接口与控制技术采用手术将电极阵列植入颅内，直接记录或刺激大脑神经元，以实现用户与外界的通信或控制神经弥补装置。目前的研究多以动物模型做实验，实现了对光标、游戏杆、机械臂以及运动小车等的控制。这种全新的通信技术可望为那些严重瘫痪患提供与外界进行交流的途径。它的发展有赖于多学科的进展与融合。     

直接神经接口与控制技术

近年来逐渐成为热点的脑—机接口是一种不依靠外周神经和肌肉组织等通常的大脑输入/输出通道的通信与控制系统。直接神经接口与控制技术采用手术将电极阵列植入颅内,直接记录或刺激大脑神经元,以实现用户与外界的通信或控制神经弥补装置。目前的研究多以动物模型做实验,实现了对光标、游戏杆、机械臂以及运动小车等的控制。这种全新的通信技术可望为那些严重瘫痪患者提供与外界进行交流的途径。它的发展有赖于多学科的进展与融合。     

面向动物机器人的柔性埋入式神经刺激器研制EI北大核心

神经刺激器是动物机器人的核心组成部分,尽管动物机器人的控制效果受到多种因素的影响,但神经刺激器的性能对动物机器人的调控效果具有决定性作用。面向动物机器人,利用柔性印制电路板技术研制了埋入式神经刺激器,不仅实现了刺激器通过控制信号产生参数可调的双相电流脉冲,而且对其携带方式、材料以及尺寸等方面也进行了优化,克服了传统背负式以及头插式神经刺激器存在的隐蔽性差且易感染的缺点。刺激器的静态、离体及在体性能测试结果表明,该刺激器不仅具有精确的脉冲波形输出能力,而且重量轻、体积小,在实验室和室外空间环境中均具有良好的在体工作性能。该项研究对于动物机器人的应用具有较高现实意义。     

电刺激狗盆神经诱导阴茎勃起血流动力学研究

本文介绍了电刺激狗盆神经诱导阴茎勃起其阴部动静脉血流量变化，为植入式神经刺激器的研究予以临床的理论支持。     

基于FPGA和真实数据集的128通道神经信号模拟器设计与实现

在神经工程研究领域,神经信号模拟器用于验证神经解码算法和脑机接口系统的性能,设计实现一种基于FPGA和上位机的128通道神经信号模拟器。上位机负责生成神经信号和常用典型信号(如正弦波、三角波、方波)数据集,通过USB接口发送给下位机转换成模拟信号输出。其中,USB实际通信速率需大于7.68MB/s,使用USB控制器芯片CY7C68013A结合FPGA实现这一功能。下位机最终实现的基本参数如下:128通道、30kSPS采样率、±10mV幅值输出范围、12位DAC分辨率。使用业内应用最广泛的神经信号采集系统,对模拟器产生的信号进行分析,得到采集设备与模拟器的整体信噪比为75dB。该模拟器具有可编辑性强、通道数易拓展、噪声小等优点,可应用于神经信号采集系统的性能测试、神经科学研究、脑机接口等领域。     

盆神经刺激器的研制

本文介绍了一种部分植入式盆神经刺激器，它主要由体外脉冲发射装置与体内感应接收器和刺激电极组成。文中描述该刺激器的电路设计原理及动物实验结果。     

部分植入式神经刺激器与压电换能器的应用研究

本文介绍了部分植入式神经刺激器植入狗体内，在成活期中，应用压电换能器与开创手术测定阴茎海绵体压力比较进行跟踪研究。     

脑-机接口中神经元放电信号的解码算法

基于神经元放电信号的脑-机接口(BCI)的核心问题是获得神经元锋电位的放电率,然后利用神经元群体解码算法解码运动轨迹。综述了当前及经典的放电率估计方法的理论依据,并对各种算法的优缺点进行了比较;同时介绍了BCI中利用放电率解码运动轨迹的主要算法：群矢量算法、线性滤波及卡尔曼滤波;最后介绍了将放电率估计算法应用于BCI中...     

Modelization of a self-opening peripheral neural interface: a feasibility study

In this paper a self-opening intrafascicular neural interface (SELINE) has been modeled using both a theoretical approach and a Finite Element (FE) analysis. This innovative self opening interface has several potential advantages such as: higher selectivity due to its three-dimensional structure and efficient anchorage system. Mechanical, structural and micro-technological issues have been considered to obtain an effective design of the electrode, as a feasibility study of the self-opening approach. A simple framework has been provided to model the insertion and partial retraction into peripheral nerves, resulting in the opening of wings.This integrated approach results in a rational procedure to optimize kinematics, geometry, and structural properties of peripheral interfaces. The design and feasibility study carried out in this work can potentially assure a correct behavior and dimensioning of the neural interface: in this way anomalous breakage should be avoided while mechanical and geometrical biocompatibility should increase.     

Structure-property relationships in the optimization of polysilicon thin films for electrical recording/stimulation of single neurons

We had earlier demonstrated the use of polysilicon microelectrodes for recording electrical activity from single neurons in vivo. Good machinability and compatibility with CMOS processing further make polysilicon an attractive interface material between biological environments on one hand and MEMS technology and digital circuits on the other hand. In this study, we focus on optimizing the polysilicon thin films for (a) electrical recording and (b) stimulation of single neurons by minimizing its electrochemical impedance spectra and maximizing its charge storage/injection capacity respectively. The structure-property relationships in ion-implanted (phosphorus) LPCVD polysilicon thin films under different annealing and doping conditions were carefully assessed during this optimization process. A 2D model of the polysilicon thin film consisting of 4 grains and 3 grain boundaries was constructed and the effect of grain size and grain boundaries on dc resistivity was simulated using device simulator ATLAS. Optimal processing conditions and doping concentrations resulted in a 10-fold decrease in electrochemical impedance from 1.1 kΩ to 0.1 kΩ at 1 kHz (area of polysilicon interface = 4.8 mm²). Subsequent characterizations showed that evolution of secondary grains within the polysilicon thin films at optimal doping and annealing conditions (10²¹/cm³ of phosphorus and annealed at 1200°C) was responsible for decreasing the impedance. Cyclic voltammetry studies demonstrated that charge storage properties of low doped (10¹⁵/cm³) thin films was 111.4 μC/cm² in phosphate buffered saline which compares well with platinum wires (∼50 μC/cm²) and the double-layered capacitance (C _dl ) could be sustained between –1 to 1 V before breakdown and hydrolysis. We conclude that polysilicon can be optimized for recording and stimulating single neurons and can be a valuable interface material between neurons and CMOS or MEMS devices.     

类脑智能研究热点及趋势

类脑智能是受大脑神经运行机制和认知行为机制启发,以计算建模为手段,通过软硬件协同实现的机器智能,具备信息处理机制上类脑、认知行为表现上类人、智能水平上达到或超越人的特点,近年来受到了各国关注.以"类脑智能"为主题,对Web of Science数据库中2010-2019年的相关文献进行检索,利用CiteSpace软件进...     

Implantable microscale neural interfaces

Implantable neural microsystems provide an interface to the nervous system, giving cellular resolution to physiological processes unattainable today with non-invasive methods. Such implantable microelectrode arrays are being developed to simultaneously sample signals at many points in the tissue, providing insight into processes such as movement control, memory formation, and perception. These electrode arrays have been microfabricated on a variety of substrates, including silicon, using both surface and bulk micromachining techniques, and more recently, polymers. Current approaches to achieving a stable long-term tissue interface focus on engineering the surface properties of the implant, including coatings that discourage protein adsorption or release bioactive molecules. The implementation of a wireless interface requires consideration of the necessary data flow, amplification, signal processing, and packaging. In future, the realization of a fully implantable neural microsystem will contribute to both diagnostic and therapeutic applications, such as a neuroprosthetic interface to restore motor functions in paralyzed patients.     

神经芯片研究新进展：微接触印刷将神经元和硅片融为一体

神经芯片是一种利用微电极阵列实现神经细胞与电子器件信息传导的生物芯片,是人工神经代偿器件的接口.它通过把活的神经元和硅电路有机地连接在一起.实现对细胞无损伤的长时程记录,并且可以施加人为刺激.目前这一领域的关键问题在于如何使神经细胞在芯片上按照电极点的位置黏附生长,建立通讯联系并提高芯片材料的信噪比.利用微加工工艺有望达到这一目的 .微接触印刷技术在其中应用最为广泛.它应用聚二甲基硅氧烷为印章,以生物大分子或有机聚合物为"墨水",把主模板上的精细图案转印到硅片材料上,从而实现对材料表面黏附底物的改性和结构的微加工.本综述简要介绍了神经芯片的研究进展,详细阐述了微接触印刷技术的研究现状,并且初步探讨了这一工艺在神经芯片领域中的最新应用.     

Integrated wireless neural interface based on the Utah electrode array

This report presents results from research towards a fully integrated, wireless neural interface consisting of a 100-channel microelectrode array, a custom-designed signal processing and telemetry IC, an inductive power receiving coil, and SMD capacitors. An integration concept for such a device was developed, and the materials and methods used to implement this concept were investigated. We developed a multi-level hybrid assembly process that used the Utah Electrode Array (UEA) as a circuit board. The signal processing IC was flip-chip bonded to the UEA using Au/Sn reflow soldering, and included amplifiers for up to 100 channels, signal processing units, an RF transmitter, and a power receiving and clock recovery module. An under bump metallization (UBM) using potentially biocompatible materials was developed and optimized, which consisted of a sputter deposited Ti/Pt/Au thin film stack with layer thicknesses of 50/150/150 nm, respectively. After flip-chip bonding, an underfiller was applied between the IC and the UEA to improve mechanical stability and prevent fluid ingress in in vivo conditions. A planar power receiving coil fabricated by patterning electroplated gold films on polyimide substrates was connected to the IC by using a custom metallized ceramic spacer and SnCu reflow soldering. The SnCu soldering was also used to assemble SMD capacitors on the UEA. The mechanical properties and stability of the optimized interconnections between the UEA and the IC and SMD components were measured. Measurements included the tape tests to evaluate UBM adhesion, shear testing between the Au/Sn solder bumps and the substrate, and accelerated lifetime testing of the long-term stability for the underfiller material coated with a a-SiC_x:H by PECVD, which was intended as a device encapsulation layer. The materials and processes used to generate the integrated neural interface device were found to yield a robust and reliable integrated package.     

用于控制短消息发送的实时脑机接口系统

目的：设计一种基于视觉诱发电位的实时脑机接口,用于控制短消息发送。方法：实时脑机接口系统由视觉刺激器、脑电采集电路、FPGA开发板、通讯模块组成。脑机接口界面包括短消息发送的目标选项和内容选项界面,受试者每次实验注视刺激界面中的一个模块,通过检测视觉诱发脑电来确定受试者做出的选择。利用基于FPGA的VGA视觉刺激器为受试者提供视觉刺激,采集脑电信号并在FPGA平台上对其进行在线的实时分析处理。选用小波分解提取视觉诱发电位特征向量,输入BP神经网络进行模式识别,产生脑机接口控制信号,其中,小波分解和BP神经网络两部分由NIOS II实现。脑机接口控制命令用于控制TC35无线模块发送短消息。结果：通过对五名受试者做实验,识别准确率最高可以达到100%,脑机接口系统能有效控制短消息的发送。采用小波滤波、BP神经网络识别的算法优于时域波形匹配识别法。结论：实验表明本文提出的实现脑机接口短消息发送系统的方法具有可行性。     

Bone ingrowth and total knee replacement

Biological fixation by bone ingrowth into prosthetic components in total knee arthroplasty is a complex process involving the integration of numerous biological and mechanical factors. These factors include the presentation of an appropriate porous-coated surface of such pore size and pore geometry as to allow bone ingrowth. Additionally, there must be intimate contact and minimal interface motion between the prosthesis and the bone for ingrowth to occur. Numerous factors have been shown to influence bone ingrowth including various types of bone graft material, electrical stimulation, drugs and ionizing radiation. The application of ingrowth biology to total knee arthroplasty technology has unique implications for the patellar, femoral and tibial prosthetic components. While the early clinical and retrival results of total knee arthroplasty using bio-ingrowth technology were somewhat controversial, more recent reports have been more favourable. As more clinical, basic science and retrieval studies become available in the 1990s the role of bio-ingrowth technology in the clinician's armamentarium will be further elucidated.     

一种用于脑机接口的模式识别方法

基于脑电的脑机接口(BCI)是在人脑和计算机或其他电子设备之间建立的全新对外信息交流和控制技术,是一种不依赖于常规大脑信息输出通路(外围神经和肌肉组织)的脑机通讯系统.及时有效地提取和识别与运动想象有关的脑电模式可以帮助运动功能受损的病人建立一种与外界沟通的新途径.论文基于传统的特征提取方法--时频特征组合法,经过滑动窗优化,获取最佳时间段的时域均值和最佳频率段的频域功率谱均值,以此作为特征向量.基于该特征向量,用径向基概率神经网络对脑电信号进行分类.实验结果表明,该方法能够有效地提高脑电识别率,具有应用价值.