基于无线充电技术的胃肠电刺激系统

目的设计一种新型的植入式胃肠道刺激系统,不仅具有刺激功能,还具有肠电和压力检测功能,可用于检测胃肠道刺激的效果,同时增加无线能量供给,以实现刺激器的长期植入。方法系统由体内刺激模块、体外控制模块及无线能量传输模块组成。体外控制模块通过无线射频将控制信号传输到体内刺激模块,体内刺激模块的能量由体外能量发射装置通过电磁耦合进行供给。通过生物反馈控制检测不同刺激参数对胃肠道收缩活动的作用效果,实时调整刺激参数,输出需要的刺激脉冲。以模拟心电信号模拟肠电信号,进行了相关的体外实验。结果在体外实验中,系统可有效检测到2—20次／min的模拟心电信号,并实现实时刺激参数修改输出不同的刺激脉冲。该系统实现了电流检测功能,监测作用部分的胃肠电阻。经皮无线能量在两级线圈轴向距离为22mm时的接收充电稳定功率最大为0．93W,体内锂离子的充电电流为180～240mA。结论系统可检测到最大变化范围的模拟肠电信号。验证电流的作用效应为后续的恒流刺激模式提供参考。该系统的无线充电功能可满足植入式刺激器长期植入的能量需求。     

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。     

实时癫痫电位检测与闭环式电刺激系统的设计

为了研究深部大脑电刺激对于癫痫等疾病的治疗作用,本文利用LabVIEW虚拟仪器环境和NI数据采集卡开发了一种闭环式电刺激系统,用于实现癫痫电信号的自动检测和刺激信号的输出。设计了结合场电位的幅值、斜率和海岸线参数3个特征量的癫痫波自动判定新算法。大鼠海马区癫痫模型的实验测试结果表明,该系统判定癫痫发作信号的正确率为91.3%,误检率为8.0%。而且,实时发生的高频电刺激展示了其抑制癫痫发作的效果。此外,系统设计了自动和手动等多种模式,具有较高的适应性和灵活性。癫痫波判定的简单时域算法也保证了系统具有较高的实时性,为电刺激控制癫痫的实验研究提供了一种简便易用的设备。     

基于单片机的植入式神经刺激器的设计

目的:介绍了一种治疗神经功能失调疾病仪器的设计方案.方法:该设计以MSP430单片机为核心控制器,包括体外控制器和体内刺激器的硬件和软件设计.结果:该仪器器能够对体内刺激器进行参数的设置和控制,使其产生可调电压幅度、频率和占空比的脉冲信号.并能接收到体外控制器发出的控制信号并产生相应的脉冲信号,该脉冲信号作用于靶点神经,用持续的脉冲电刺激抑制不正常的神经放电,达到治疗效果.结论:该系统进一步的完善将有较好的应用前景.     

基于电磁感应的消化道内微系统无线能量传输问题研究

针对消化道内微小系统,提出一种基于电磁耦合的无线能量传输方案.通过计算线圈间的互感,分析了相对位置对耦合系数的影响.建立了能量传输模型,推导出弱耦合情况下接收功率最大化的条件,指出提高传输效率的两种方法.实验传输功率超过200 mW(接收线圈位于发射线圈中心),验证了这种方案的可行性.     

人工肛门括约肌经皮能量传输系统研究

针对现有人工肛门括约肌系统无供能装置或供能装置更换可能引发感染等问题,本文提出了电磁谐振耦合的无线供能方法,对人工肛门括约肌系统进行非接触的经皮无线供能.本文在对能量传输电路、发送接收线圈参数研究基础上,提出通过选择SRC电路作为发射、接收端耦合电路以增大铁芯耦合面积,从而提高发射及接收线圈Q值,进而提高能量传输效率.实验结果表明,使用G25磁芯线圈进行电磁耦合,当两线圈轴向距离为10mm时,能量传输效率可高于60%,可保证人工肛门括约肌系统的正常工作.     

中国版“脑起搏器”即将进入临床试验阶段

在医学上,“脑起搏器”也被称为“脑深部电刺激器”，通过植入式神经刺激器发出的脉冲信号，对帕金森病和癫痫等脑部神经疾病进行治疗。1999年脑起搏器首次应用于我国临床，但全部被国外公司垄断，且价格昂贵，一般都在十几万元。清华大学教授李路明的研究团队利用载人航天等技术，研制出符合我国国情的植入式神经刺激疗法和刺激器，新仪器即将进入人体临床试验。     

TMS线圈与EEG电极线相对位置对TMS-EEG信号的影响

通过分析经颅磁刺激线圈放电时的电场分布,探索磁刺激输出脉冲对脑电采集帽产生的伪迹信号来源。我们通过建立八字线圈感应电场分布的半无界空间数学模型,获得八字线圈感应电场的分布特性,分析磁刺激影响脑电采集回路的两种影响因素,我们用matlab软件仿真刺激线圈与脑电极线成不同角度、不同距离时产生的伪迹信号的变化趋势,通过模型试验和人体实验验证这种趋势的准确性;结果显示,脑电导线重合于线圈长轴,产生脑电伪迹最小,当线圈转动其他角度或当线圈下移时伪迹会逐渐增大,最大伪迹幅值是最小伪迹幅值的约10倍。在TMS-EEG试验中,伪迹信号的幅值、持续时间与线圈摆放位置、角度有关。通过实验前合理排布脑电极线可降低伪迹信号幅值、持续时间等参数,提高磁刺激下脑电信号特征信号提取的准确性。     

慢性脑神经刺激电参数及刺激器的应用技术

在人脑和中枢神经系统植入电脉冲刺激器,是治疗神经性疾病的有效方法,但对刺激电参数的控制是该技术的关键,它不仅直接影响治疗效果,而且对减少或预防由刺激引起的有害的电化学反应起决定性作用。本文综述了有关慢性脑神经刺激电参数研究情况以及刺激器的应用技术,认为:刺激脉冲须经电容耦合;采用对称双向波;双相脉冲每一相电荷量限制在0.5微库以下;用惰性金属制作电极;刺激频率为15～100Hz,脉宽为0.1～0.5ms。     

基于局部场电位样本熵分析的麻醉深度监测

背景：目前的麻醉深度监测多以大脑皮质脑电信号分析为主,然而,大脑皮质脑电信号不能反映皮质下组织的功能状况、不包含高频信息并且易受外界环境干扰,从而导致基于大脑皮质脑电信号分析的麻醉深度监测在稳定性、精确性等方面有固有缺陷。 目的：分析局部场电位信号样本熵在麻醉深度监测中的效果,实现麻醉深度的实时监测。 方法：以大鼠为模型动物进行实验,对整个麻醉过程中的大鼠初级视觉皮质局部场电位信号进行快速样本熵计算,并对样本熵曲线动态变化进行分析,判定麻醉状态;然后将样本熵分别与大鼠尾部受热刺激时的甩尾延迟时间、局部场电位信号的中心频率和边缘频率做统计分析,验证基于局部场电位快速样本熵分析的麻醉状态判定方法。 结果与结论：局部场电位信号的样本熵可以快速、准确、稳定地反映大鼠的麻醉深度,用于麻醉深度实时监测。     

Transcutaneous,dual channel phrenic nerve stimulator for diaphragm pacing

An electrical stimulation system for bilateral diaphragm pacing was constructed. The stimulator instrument comprises a transmitter and two implantable receivers and nerve electrodes. An optimised transcutaneous link system is described which utilises a radio frequency coupling to transmit both power and stimulus information to the receiver. The receiver unit was constructed in thick-film hybrid technology using bipolar and c.m.o.s. circuits and was packaged in a hermetically sealed metal case. The construction of the transmitter allows a high reliability, low power consumption and flexibility of the stimulus parameter control. A complete, bilateral phrenic nerve pacing system was implanted into a patient suffering from tetraplegia. It is concluded that electrical phrenic nerve stimulation to pace the diaphragm is capable of being used in clinical therapy.     

双向脉冲可实现的神经纤维选择性兴奋

背景：研究证明利用电刺激外周神经纤维可恢复一些因失去中枢神经控制的肌肉的功能。 目的：验证双电极1 mm较近距离下双向方波脉冲实现神经选择性兴奋的正确性,并基于此实现神经的选择性兴奋。 方法：成年Wistar大鼠8只,麻醉后暴露大鼠坐骨神经,将电极小心放于坐骨神经干,建立神经选择性刺激模型。实验用电极为自制Cuff双极性电极,刺激器采用的是Grass S88刺激器和AWG2005任意波形信号发生器。采取双电极双向刺激方式,两个电极之间距离为1 mm,刺激波形选用脉宽为0.2 ms的对称双向脉冲,其输出脉冲的幅度、脉宽和延时均可调。调节刺激强度,研究双电极双向刺激下神经兴奋性的规律,以此实现神经的选择性兴奋,并利用“碰撞法”原理验证利用双电极双向刺激方法实现神经选择性兴奋的可行性。 结果与结论：实验过程中神经动作电位的变化将经P511放大器放大后接入示波器显示,双电极刺激波形为脉宽为0.2 ms的对称双向脉冲。随着刺激幅度的增大,实现神经的选择性兴奋。说明用距离很近(1 mm)的双电极双向对称脉冲的方法实现了神经的选择性兴奋,并利用“碰撞法”原理证实了此种方法的有效性和可行性。     

Implantable stimulation system dedicated for neural selective stimulation

A functional electrical stimulation system is presented, which is dedicated for the selective neural stimulation of the bladder. The proposed system is composed of an internal stimulator (implant) and an external controller. The system is used to produce low-pressure voiding of the bladder in spinal cord injured patients. The implant is powered and operated by the external controller via radio-frequency electromagnetic coupling. All stimulation parameters are chosen externally using the controller and are sent to the implant, which produces the desired stimuli. These stimuli are applied directly to the S₂ nerve which is linked to the sphincter and bladder muscles. A high-frequency signal is used to inhibit the contraction of the sphincter muscle, and low-frequency pulses stimulate the bladder muscle (the detrusor). Dedicated computer software is used by the physician to select the optimal parameters for each patient and to activate the implant through a parallel port interface with built-in transmitter. The parameters are then transferred to a hand-held controller which is used by the technical staff and by the patients themselves. Acute studies have been performed to validate the selective stimulation strategy, and chronic experimentation is currently underway in dogs.     

A design of an artificial control system of the cardiac output

Summary An automatic control system of the cardiac output of a dog was designed by a method where a cardiac vagus and the heart were involved in the feedback system. The cardiac output was measured at the ascending aorta by a sine wave electromagnetic flowmeter. The output voltage of the flowmeter was compared with a controllable reference voltage. The error voltage was amplified or integrated, and converted to pulses of the frequencies which was proportional to the input of the AD convertor. A peripheral cut end of a vagus was stimulated by an electric stimulator triggered by those pulses. Vagal stimuli decrease the cardiac output by their negative chronotropic and inotropic action. The error approximated zero when the feedback loop gain was more than about 10 or an integral control was used. Complete stability could not be achieved with a zero error and an unstable oscillation of the smoothed cardiac output signal with a period of several seconds was observed. However, the instability was slight and did not disturb its application. Effects of disturbances such as change of venous return and peripheral resistance were sufficiently reduced.     

不同刺激模式对神经传导阻断影响的仿真研究

目的为减少长期电刺激导致的神经疲劳,提高治疗效率,本研究比较多种刺激模式在神经传导阻断中的阻断阈值,为动物实验选择最好的刺激模式。方法以有限长单根有髓神经为研究对象,采用有髓神经纤维Frankenhaeuser-Huxley(F-H)模型进行仿真,比较双向对称方波、正弦波、双向对称方波簇的阻断阈值以及叠加不同信噪比的双向对称方波阻断阈值。结果在刺激频率范围内,对称方波的阻断波形低于正弦波和方波簇的刺激阻断阈值。对于叠加噪声的对称方波,叠加-50 d B的高斯白噪声能够降低方波的阻断阈值。结论方波的阻断阈值低于正弦波和方波簇。在相同的条件下,叠加高斯白噪声对方波阻断阈值的影响明显,尤其是叠加-50 d B的噪声。     

Fuzzy FES controller using cycle-to-cycle control for repetitive movement training in motor rehabilitation. Experimental tests with wireless system

A prototype of wireless surface electrical stimulation system combined with the fuzzy FES controller was developed for rehabilitation training with functional electrical stimulation (FES). The developed FES system has three features for rehabilitation training: small-sized electrical stimulator for surface FES, wireless connection between controller and stimulators, and between controller and sensors, and the fuzzy FES controller based on the cycle-to-cycle control for repetitive training. The developed stimulator could generate monophasic or biphasic high voltage stimulus pulse and could output stimulation pulses continuously more than 20 hours with 4 AAA batteries. The developed system was examined with neurologically intact subjects and hemiplegic subjects in knee joint control. The maximum knee joint angle was controlled by regulating burst duration of stimulation pulses by the fuzzy controller. In the results of two experiments of knee extension angle control and knee flexion and extension angle control, the maximum angles reached their targets within small number of cycles and were controlled stably in the stimulation cycles after reaching the target. The fuzzy FES controller based on the cycle-to-cycle control worked effectively to reach the target angle and to compensate difference in muscle properties between subjects. The developed wireless surface FES system would be practical in clinical applications of repetitive execution of similar movements of the limbs for motor rehabilitation with FES.     

Intracranial measurement of current densities induced by transcranial magnetic stimulation in the human brain

Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses the principle of electromagnetic induction to generate currents in the brain via pulsed magnetic fields. The magnitude of such induced currents is unknown. In this study we measured the TMS induced current densities in a patient with implanted depth electrodes for epilepsy monitoring. A maximum current density of 12 microA/cm2 was recorded at a depth of 1 cm from scalp surface with the optimum stimulation orientation used in the experiment and an intensity of 7% of the maximal stimulator output. During TMS we recorded relative current variations under different stimulating coil orientations and at different points in the subject's brain. The results were in accordance with current theoretical models. The induced currents decayed with distance form the coil and varied with alterations in coil orientations. These results provide novel insight into the physical and neurophysiological processes of TMS.     

Selective stimulation of smaller nerve fibers by single electrode using Biphasic Rectangular Pulses

INTRODUCTION　　Selectivestimulationofsmallernervefibersinacompoundnervetrunkisanim-portantprobleminFunctionalElectricalStimulation(FES)ofthemotorsysteminpatientshavinguppermotorneuroninjures.Undernormalphysiologicalconditions,theneverfibersinacompoundner…     

经颅磁刺激的多尺度建模仿真研究

经颅磁刺激是一种无创无痛的电磁刺激手段，被广泛应用于神经调控，在临床上对多种精神疾病和神经类疾病有明显的治疗效果。本文从电磁场建模仿真，细胞跨膜电位建模仿真，以及神经元响应建模仿真3个方面对经颅磁刺激多尺度建模仿真研究进行了详细的综述，并提出现阶段存在的问题以及对未来的展望。经颅磁刺激的多尺度建模仿真对磁刺激仪的设计开发具有指导意义，对磁刺激的导航系统提供重要的理论基础，有助于我们更好的理解电磁刺激的神经调控机制。