基于中国数字人的经皮神经电刺激信号传导机制建模与分析

目的:研究经皮神经电刺激(TENS)在实施肌肉刺激时信号在内部的传导情况,为理想刺激提供理论依据。方法:以中国数字人为数据基础,先使用Mimics软件完成组织分割与三维建模;考虑到多物理场有限元建模软件只能使用几何实体,接下来使用Geomagic软件完成组织的实体建模,得到组织的几何实体;最后将获得的几何实体在COMSOL Multiphysics 5.5中建模,并在频域环境下,通过注入20 mA的直流电信号分析信号在手臂中的传播机制。结果:由于皮肤存在集皮肤效应,信号主要集中在电极以及电极与皮肤的接触处,分析位置离电极中心位置越远,人体手臂内部感应电势越小,并且感应电势逐渐变为正电势。在手臂内部,骨骼不传导信号,但骨骼形状及数量会影响电流密度分布的均匀性。结论:在基于中国数字人的TNES信号传导模型中,传导距离越远,信号衰减越大;内部组织结构越复杂,信号分布也越不均匀。     

电子镇痛仪电信号传导机制模型建立与分析

目的:分析电子镇痛仪电流信号在手臂肌肉内的信号传导情况,为电刺激镇痛提供理论依据。方法:结合人体解剖学与组织结构学,在COMSOL Multiphysics 5.5有限元仿真软件中,利用圆台、圆柱、椭球为几何实体,建立电子镇痛仪数值仿真有限元模型。在频域环境下,通过注入载波信号分别为100 kHz、1 MHz、10 MHz,幅度为±20 mA的电流信号,以此分析信号在手臂中的传播机制。结果:随着载波频率的不断增加,集肤效应越来越明显,信号在电极接触处皮肤部分越来越集中,容积导体内部的扩散性也将失去一致性。在100 kHz时,随着离电极中心的通信距离逐渐增加,信号在手臂内部信号扩散变得越来越均匀。结论:在电子镇痛仪实施肌肉酸痛治疗过程中,通信频率越高,信号越难以进入机体内部,信号一致性越差。因此,在实施电流镇痛过程中,信号电极应尽量布置在镇痛靶向区域附近。     

经颅磁刺激和脑电联合作用时电磁场分布的仿真研究

目的：研究分析经颅磁刺激和脑电（TMS-EEG）联合作用时磁感应强度和感应电场强度的分布情况。方法：利用有限元多物理场仿真软件COMSOL，搭建3层同心球人头模型、TMS线圈模型和EEG电极模型，在TMS线圈的作用下，对比分析了有无脑电极时，人头模型当中磁感应强度和感应电场强度的不同。结果：取头部组织几个特殊位置点，放置脑电极后，各点处磁感应强度和感应电场强度均发生变化，磁感应强度最大变化达19.19%，感应电场强度最大变化达75.33%。添加脑电极后，人体头部组织YZ纵切面的最大磁感应强度降低7 mT，最大感应电场强度值降低0.6 V/m。大脑处的三维磁感应强度和感应电场强度均随着深度的增加而逐渐减小，放置脑电极后，脑组织中的最大磁感应强度值减少1.4 mT，最大感应电场强度值减少0.13 V/m。结论：经TMS-EEG联合作用时，在人头皮处放置脑电极会对电磁场的分布产生影响，间接影响TMS的治疗作用。     

基于混沌信号的经皮神经电刺激仪的设计

传统的电刺激仪器都是采用三角波、方波与非对称波等信号作为刺激信号源,或是将一些特定的信号先进行存储、然后再输出作为信号源,这些信号都呈现出周期性,作用于人体时容易使人产生适应性,随着刺激次数的增多而使效果逐渐变差,论文设计了一个基于混沌模型的非周期信号的电刺激系统。首先是在MATLAB软件的Simulink平台下构建出混沌模型,然后借助于DSP Builder软件将混沌模型转换为FPGA的工程文件,通过Simulink平台的模型仿真及Modelsim软件的行为级仿真,仿真无误后将工程文件在Altera公司的开发平台Quartus软件下进行编译、综合,最后生成可执行文件,下载到FPGA芯片即产生了混沌信号;将信号进行电压放大,功率放大,接入电极,实现了基于混沌信号的电刺激系统。所设计的系统获得了新型的电刺激效果,通过改变混沌方程的参数以及改变信号的输出频率,可以改变刺激时的直观感觉,由于人体的生物信号本身具有复杂的混沌特性,用它作用于人体所具有的更深层次的生物效应还需更多的探索研究。     

FNS肢体运动疲劳特性的实验研究

研究了功能电刺激作用下的人体神经肌肉的疲劳特性和生物反应,初步确定了适合于人体神经肌肉电刺激脉冲信号的基本特征,以正常男性成人的曲肘运动（右手）为研究对象,将表面电极置于右手肱二头肌肌腹处,在肘关系（右手）处安装一个微型角位移传感器,通过多功能神经肌肉电刺激肢体运动测控仪器,获取曲肘运动时的肘关节角位移变化曲线,结果表明,在任何一种刺激模式作用下,曲肘运动均呈现严重非线性时变特性;缓慢连续变化的刺激脉冲能有效地缓解肱二头肌的疲劳程度,最佳的功能电刺激脉冲频率为30Hz-50Hz。     

外部电场作用下的视神经纤维兴奋性的仿真研究

基于刺入式电极的视神经视觉假体,为盲人的视觉修复提供了新的可能性。为了对该视神经假体的电刺激策略和微电极设计提供理论支持,基于真实的电极结构,在COMSOL软件中建立刺入式微电极的外部电场仿真模型,并将其与利用NEURNO软件实现的神经纤维双层电缆模型结合,系统地研究电极与视神经纤维的相对位置、电刺激脉冲宽度以及电极几何结构的改变对视神经纤维兴奋阈值的影响。不同电极位置、刺激脉宽刺激下阈值变化规律的仿真结果,与以往报道的动物实验和仿真实验结果相符,证明了所建模型的有效性。 根据仿真结果,对刺入式视神经假体中刺激脉宽的选择和电极几何结构的设计,建议如下：窄脉宽刺激有利于降低能量消耗;电极锥度的设计要在满足电极力学特性及易于植入视神经的基础上,尽可能地减小,以降低纤维兴奋的阈值;电极的暴露面积越小,纤维兴奋所需的电流阈值越低,但电荷密度阈值越高;较低的电流阈值有利于减少能量消耗,但过高的电荷密度阈值却容易造成组织损伤,因此电极暴露面积的设计需要在耗能与安全性之间进行综合考虑。电极绝缘层厚度的改变对视神经纤维的兴奋阈值没有明显的影响,但从电极插入的难易考虑,应尽可能减小绝缘层厚度。以上结果对人体其他部位神经纤维的电刺激同样具有参考价值     

电针技术电化疗肌肉内血管瘤电传导机制建模与分析

目的:基于电针的电化学治疗方法,通过向电针中注入直流电信号,利用电流弥散来实现对肿瘤细胞的电解、电渗作用,实现癌症的定向精准治疗,为了研究电针信号在手臂肌肉内的信号传导情况,为精准治疗提供理论依据。方法:结合人体解剖学与组织结构学,在COMSOL Multiphysics 5.5有限元仿真软件中,利用圆台、圆柱、椭球为几何实体,建立电针电化疗数值仿真有限元模型,并在频域环境下,通过注入载波信号为100 kHz、±20 mA的直流电信号,以此分析信号在手臂中的传播机制。结果:感应电势、电流密度分布主要集中在裸露电针头部周围,电势衰减约为11 dB/cm,距离较远时几乎检测不到通过电针注入的电流信号。结论:在精准电化疗肿瘤治疗系统中,传导距离越远,信号衰减越大,距离较远时,检测端几乎检测不到通过电针注入的电流信号,充分说明电针治疗几乎不会对离它具有一定距离（距离大小根据电针大小与注入电流情况而改变）的设备产生影响。     

神经纤维双向选择性刺激方法仿真研究

双向选择性刺激是避免神经纤维电化学损伤、使肌肉平稳收缩、降低疲劳的有效电刺激模式。利用计算机模型仿真，提出了单电极、双电极和三电极三种双向刺激模式，有效地实现了选择性刺激，推进了神经电刺激向临床应用迈进的步伐。     

多参数经皮神经肌肉电刺激仪的设计

目的：电刺激仪器是通过电流作用于目标组织，使目标组织产生相应的功能变化。刺激方式、刺激电流、波形等均会影响治疗效果。市面上现有的神经肌肉电刺激仪一般只有单一的治疗模式，局限性很大。为了有针对性地治疗不同肌肉疾病，我们设计了一个能够方便准确地控制刺激电流的多参数经皮神经肌肉电刺激仪系统：方法：设计了一个以STC12C5410AD单片机为核心控制芯片的多参数经皮神经肌肉电刺激仪系统，采用串口实现上下位机的通讯，通过软件编程，上位机发送波形、频率、脉宽、间隙时间、最大刺激电流等各项参数指令，由单片机控制D／A转换芯片DAC8532输出指定波形，经过高压开关保护电路加入恒流源电路，产生恒定的电流对目标组织进行刺激。系统加入多项安全控制措施，有效地避免了实际操作过程中的安全隐患；结果：通过对系统进行电阻测试，验证了系统为恒流型仪器，经过电阻的刺激电流由且仅由输入信号的各项参数确定，与电阻的大小无关。由临床试验证明了通过改变参数，可以改变刺激模式，并验证了该系统的安全性和有效性。结论：该系统能设置成临床上使用的经皮电神经刺激疗法的各种模式。安全有效，有利于临床实验和相关科研的开展。     

基于2^n伪随机复合频率信号的神经肌肉电刺激系统设计

目的：每一块肌肉都是由众多肌纤维组成,每一组肌纤维的固有频率不同,在对肌肉进行电刺激时,使用单一频率的电刺激不能满足同时对多组肌纤维进行刺激,不能达到最有效的电刺激作用,因此我们设计了一种基于伪随机信号的复合频率电刺激仪,能在一个刺激周期内实现多个频率的电刺激。方法：设计了一个以STC12C5410AD单片机为核心控制芯片的伪随机信号神经肌肉电刺激仪系统,采用串口实现上下位机的通讯,通过软件编程,上位机发送主频数、主频频率、间歇时间和刺激时间各项参数指令,由单片机控制输出两路伪随机脉冲信号,并通过逆变电路实现伪随机信号的输出,在逆变电路中加入电流监测电阻,实时监测输出信号的电流大小,将其控制在人体安全电流10mA以下,保证了用户的使用安全。结果：研制出的电刺激仪能产生1kHz以下多种主频信号的复合,根据主频数和主频频率的不同输出不同的复合频率信号,同时对输出电流的检测,验证了信号的安全性。结论：本文将伪随机复合频率信号运用于肌肉电刺激仪中,取代传统的单一频率电刺激仪,实现了技术上和理论上的创新,具有较高的临床实验和科研价值。     

Gradual potentiation of isometric muscle force during constant electrical stimulation

An investigation was carried out into how stimulation frequency and stimulation history affect the potentiation of muscle force during 20s of constant stimulation of the two knee extensors in isometric conditions. Stimulation frequency significantly affected the potentiation pattern: low-frequency (2.5–10 Hz) stimulation showed a reduction and subsequent enhancement of force, and high-frequency (14.3–25 Hz) stimulation showed only enhancement of force. The degree of enhancement in force and time-to-peak decreased with the stimulation frequency. Whereas conditioning stimulation (both 40 Hz and 14.3 Hz) significantly enhanced the muscle force above 85%, following main stimulation (14.3 Hz) after short rest (10 s and 50 s, respectively) induced little force enhancement (below 8%). In particular, when the frequency of the conditioning stimulation was 14.3 Hz, the initial force at the main stimulation showed a very similar value to the final force value of the conditioning stimulation (above 90% similarity). The potentiated twitch force slowly decayed during rest, with an average time constant of 2.4 min. These observations indicate that muscle potentiation depends on the stimulation frequency and stimulation history, and therefore a computer model of potentiation can play an important role in predicting muscle force and body movement induced by electrical stimulation.     

A model for transcutaneous current stimulation: simulations and experiments

Complex nerve models have been developed for describing the generation of action potentials in humans. Such nerve models have primarily been used to model implantable electrical stimulation systems, where the stimulation electrodes are close to the nerve (near-field). To address if these nerve models can also be used to model transcutaneous electrical stimulation (TES) (far-field), we have developed a TES model that comprises a volume conductor and different previously published non-linear nerve models. The volume conductor models the resistive and capacitive properties of electrodes, electrode-skin interface, skin, fat, muscle, and bone. The non-linear nerve models were used to conclude from the potential field within the volume conductor on nerve activation. A comparison of simulated and experimentally measured chronaxie values (a measure for the excitability of nerves) and muscle twitch forces on human volunteers allowed us to conclude that some of the published nerve models can be used in TES models. The presented TES model provides a first step to more extensive model implementations for TES in which e.g., multi-array electrode configurations can be tested.     

Influence of transcutaneous electrical stimulation on heterotopic ossification: an experimental study in Wistar rats

Heterotopic ossification (HO) is a metaplastic biological process in which there is newly formed bone in soft tissues, resulting in joint mobility deficit and pain. Different treatment modalities have been tried to prevent HO development, but there is no consensus on a therapeutic approach. Since electrical stimulation is a widely used resource in physiotherapy practice to stimulate joint mobility, with analgesic and anti-inflammatory effects, its usefulness for HO treatment was investigated. We aimed to identify the influence of electrical stimulation on induced HO in Wistar rats. Thirty-six male rats (350-390 g) were used, and all animals were anesthetized for blood sampling before HO induction, to quantify the serum alkaline phosphatase. HO induction was performed by bone marrow implantation in both quadriceps of the animals, which were then divided into 3 groups: control (CG), transcutaneous electrical nerve stimulation (TENS) group (TG), and functional electrical stimulation (FES) group (FG) with 12 rats each. All animals were anesthetized and electrically stimulated twice per week, for 35 days from induction day. After this period, another blood sample was collected and quadriceps muscles were bilaterally removed for histological and calcium analysis and the rats were killed. Calcium levels in muscles showed significantly lower results when comparing TG and FG (P<0.001) and between TG and CG (P<0.001). Qualitative histological analyses confirmed 100% HO in FG and CG, while in TG the HO was detected in 54.5% of the animals. The effects of the muscle contractions caused by FES increased HO, while anti-inflammatory effects of TENS reduced HO.     

基于EIT技术颅内电阻抗特性分析

电阻抗断层成像技术（EIT）是一种基于生物组织电学特性的成像技术。本研究基于EIT技术对二维四层同心圆头模型和基于MRI图片构造的脑电二维真实头模型的电阻抗特性进行了分析，给出了头部组织电导率参数变化对求解区域场内及头皮表面电位分布的影响，得出了有实际意义的结论，为实现颅内EIT逆问题求解和阻抗成像及脑内电特性的深入研究奠定了基础。     

电刺激骨骼肌产生收缩肌力的数学模型

神经肌肉电刺激是用脉冲电流来刺激骨骼肌收缩从而产生运动或增强肌力的康复或锻炼方法,为了精确地控制肌力输出,需要建立电刺激肌肉系统的数学模型。较为全面地阐述了近年来此类模型的原理、结构形式及预测收缩肌力的效果,并对今后如何改善肌力模型从而更好地优化电刺激模式提出了设想。     

Facial muscle reanimation by transcutaneous electrical stimulation for peripheral facial nerve palsy

Abstract

Reanimation of paralysed facial muscles by electrical stimulation has been studied extensively in animal models, but human studies in this field are largely lacking. Twenty-four subjects with a peripheral facial nerve palsy with a median duration of three years were enrolled. We studied activations of four facial muscles with electrical stimulation using surface electrodes. In subjects whose voluntary movement was severely impaired or completely absent, the electrical stimulation produced a movement that was greater in amplitude compared with the voluntary effort in 10 out of 18 subjects in the frontalis muscle, in 5 out of 14 subjects in the zygomaticus major muscle, and in 3 out of 8 subjects in the orbicularis oris muscle. The electrical stimulation produced a stronger blink in 8 subjects out of 22 compared with their spontaneous blinks. The stimulation could produce a better movement even in cases where the muscles were clinically completely paretic, sometimes also in palsies that were several years old, provided that the muscle was not totally denervated. Restoring the function of paralysed facial muscles by electrical stimulation has potential as a therapeutic option in cases where the muscle is clinically paretic but has reinnervation.