一种无线多通道动物神经刺激系统

设计了一种无线多通道电刺激系统,硬件部分包括了无线通信模块和神经刺激器单元2部分,后台软件包括了基于LabVIEW的上位机控制.无线通信部分用了包含基于蓝牙形式的串口通信通道和基于2.4 G无线收发的2个通道部分,以方便调试和实际远程遥控.神经刺激器单元包含了常见的锂电池3.7 V供电升压电源电路、STM32最小系统、双极性压控恒流源电路、4通道模拟开关等模块.为了实现多点的并发控制,本刺激器模块有4个通道的单独输出,同时能实现其中任意两个通道的同时输出,每个通道的恒电流波形参数如脉冲频率、占空比、强度、簇个数等参数均可独立设置.实验结果表明:在负载阻抗低于10 kΩ的情况下,本无线多通道动物神经刺激系统可以实现500 m左右的实时多通道远程控制.     

A power‐efficient current‐mode neural/muscular stimulator design for peripheral nerve prosthesis

This paper presents a 16‐channel power‐efficient neural/muscular stimulation integrated circuit for peripheral nerve prosthesis. First, the theoretical analysis is presented to show the power efficiency optimization in a stimulator. Moreover, a continuous‐time, biphasic exponential‐current‐waveform generation circuit is designed based on Taylor series approximation and implemented in the proposed stimulation chip to optimize the power efficiency. In the 16‐channel stimulator chip design, each channel of the stimulator consists of a current copier, an exponential current generator, an active charge‐balancing circuit, and a 24‐V output stage. Stimulation amplitude, pulse width, and frequency can be set and adjusted through an external field‐programmable gate array by sending serial commands. Finally, the proposed stimulator chip has been fabricated in a 0.18‐μm advanced complementary metal‐oxide‐semiconductor process with 24‐V laterally diffused metal oxide semiconductor option. The maximum stimulation power efficiency of 95.9% is achieved at the output stage with an electrode model of 10‐kΩ resistance and 100‐nF capacitance. Animal experiment results further demonstrate the power efficiency improvement and effectiveness of the stimulator.     

An Integrated Implantable Stimulator That is Fail-Safe Without Off-Chip Blocking-Capacitors

We present a neural stimulator chip with an output stage (electrode driving circuit) that is fail-safe under single-fault conditions without the need for off-chip blocking-capacitors. To miniaturize the stimulator output stage two novel techniques are introduced. The first technique is a new current generator circuit reducing to a single step the translation of the digital input bits into the stimulus current, thus minimizing silicon area and power consumption compared to previous works. The current generator uses voltage-controlled resistors implemented by MOS transistors in the deep triode region. The second technique is a new stimulator output stage circuit with blocking-capacitor safety protection using a high-frequency current-switching (HFCS) technique. Unlike conventional stimulator output stage circuits for implantable functional electrical stimulation (FES) systems which require blocking-capacitors in the microfarad range, our proposed approach allows capacitance reduction to the picofarad range, thus the blocking-capacitors can be integrated on-chip. The prototype four-channel neural stimulator chip was fabricated in XFAB's 1-$mu{hbox {m}}$ silicon-on-insulator CMOS technology and can operate from a power supply between 5–18 V. The stimulus current is generated by active charging and passive discharging. We obtained recordings of action potentials and a strength-duration curve from the sciatic nerve of a frog with the stimulator chip which demonstrate the HFCS technique. The average power consumption for a typical 1-mA 20-Hz single-channel stimulation using a book electrode, is 200 $mu{hbox {W}}$ from a 6 V power supply. The silicon area occupation is 0.38 ${hbox {mm}}^{2}$ per channel.      

Emerging Technologies

One of the most promising medical device therapies is neurostimulation. Advances in implantable device technologies make it now possible for patients suffering from a wide array of debilitating neurological conditions to receive adequate treatment. Implantable neurostimulation systems include cochlear implants, cortical stimulators, deep brain stimulators (DBSs), gastric nerve stimulators, spinal cord stimulators (SCSs), and vagus nerve stimulators (VNSs). Neurostimulation currently treats several debilitating conditions, including major treatmentresistant depression, epilepsy, gastroparesis, hearing loss, incontinence, chronic, untreatable pain, Parkinson disease, essential tremor, and dystonia [1]?[3].     

Effect of Bipolar Cuff Electrode Design on Block Thresholds in High-Frequency Electrical Neural Conduction Block

Many medical conditions are characterized by undesired or pathological peripheral neurological activity. The local delivery of high-frequency alternating currents (HFAC) has been shown to be a fast acting and quickly reversible method of blocking neural conduction and may provide a treatment alternative for eliminating pathological neural activity in these conditions. This work represents the first formal study of electrode design for high-frequency nerve block, and demonstrates that the interpolar separation distance for a bipolar electrode influences the current amplitudes required to achieve conduction block in both computer simulations and mammalian whole nerve experiments. The minimal current required to achieve block is also dependent on the diameter of the fibers being blocked and the electrode–fiber distance. Single fiber simulations suggest that minimizing the block threshold can be achieved by maximizing both the bipolar activating function (by adjusting the bipolar electrode contact separation distance) and a synergistic addition of membrane sodium currents generated by each of the two bipolar electrode contacts. For a rat sciatic nerve, 1.0–2.0 mm represented the optimal interpolar distance for minimizing current delivery.      

基于磁脉冲压缩的DBD高频双极性纳秒脉冲发生器的设计及其放电特性

作为高压高重复频率脉冲电压发生器的开关器件,磁开关的耐压、通流能力以及寿命远高于半导体开关,因而适用作为介质阻挡放电(DBD)激励电源的开关。为研究双极性高频下DBD等离子体放电特性,提出高频双极性磁脉冲压缩系统。首先,阐释通过全桥逆变电路、脉冲变压器和磁开关产生双极性脉冲的原理,并叙述该系统关键器件的设计;其次,利用PSpice仿真软件研究电路关键参数对输出波形的影响规律,测试电阻性负载电压波形,并与仿真结果进行对比分析。测试结果表明,通过双极性磁脉冲压缩系统,能够在负载两端输出的纳秒脉冲电压具有以下参数:幅值在5~13k V可调,上升沿100ns左右,重复频率可高至几千Hz。最后,针对高频双极性下的放电现象进行研究,结合DBD放电模型和放电图片探索高频双极性脉冲电压下放电特性与频率的关系,充实了高频放电理论研究。     

Electronic design of a multichannel programmable implant for neuromuscular electrical stimulation.

An advanced stimulator for neuromuscular stimulation of spinal cord injured patients has been developed. The stimulator is externally controlled and powered by a single encoded radio frequency carrier and has four independently controlled bipolar stimulation channels. It offers a wide range of reprogrammability and flexibility, and can be used in many neuromuscular electrical stimulation applications. The implant system is adaptable to patient's needs and to future developments in stimulation algorithms by reprogramming the stimulator. The stimulator is capable of generating a wide range of stimulation waveforms and stimulation patterns and therefore is very suitable for selective nerve stimulation techniques. The reliability of the implant has been increased by using a forward error detection and correction communication protocol and by designing the chip for structural testability based on scan test approach. Implemented testability scheme makes it possible to verify the complete functionality of the implant before and after implantation. The stimulators architecture is designed to be modular and therefore its different blocks can be reused as standard building blocks in the design and implementation of other neuromuscular prostheses. Design for low-power techniques have also been employed to reduce power consumption of the electronic circuitry.     

Compact, Nanosecond, High Repetition Rate, Pulse Generator for Bioelectric Studies

The high dielectric strength and high permittivity of water allow for its use for energy storage and switching in compact pulse power systems. A 10-Omega pulse generator with flowing water as dielectric and as the switching medium is presented here. It can provide a 10-ns pulse with a risetime of approximately 2 ns and an amplitude of up to 35 kV into a matched load. The system was operated in burst mode with repetition rates of up to 400 Hz, limited by the charging power supply. For a switch with two pin electrodes, strong electrode erosion limits the use of the pulser to less than 1,000 pulses before electrode readjustment is necessary. A considerable reduction of the erosion effect on breakdown voltage was obtained with coaxial electrodes. The pulse generator was used to study the effect of the repetition rate (or the time between successive pulses) on the viability of B16 murine melanoma cells.     

用于变频电机绝缘测试的PWM电压发生器

在变频电机绝缘测试中,重复脉冲方波电压不能完全模拟变频器输出的PWM电压反映变频电机绝缘失效机理,并且同一实验中使用不同电源影响实验数据的一致性。该文章设计了一台直接输出式PWM电压发生器,既可以输出模拟变频器实际的SPWM电压和SVPWM电压用于绝缘测试,又可以输出重复脉冲方波电压开展对比实验。首先,设计了基于FPGA的脉冲信号发生器,产生基波频率、开关频率可调的SPWM、SVPWM触发脉冲以及频率、占空比可调的重复方波脉冲;然后,设计了基于固态推挽开关的斩波器,在脉冲信号的触发下输出对应的双极性高压脉冲;最后,使用该脉冲电压发生器开展了SPWM电压下变频电机绝缘局部放电实验,验证了系统的可靠性和实用性。     

基于Marx电路的全固态纳秒脉冲等离子体射流装置的研制

研制一套具有快边沿纳秒脉冲等离子体射流装置。该装置由基于Marx电路的并带有尾切开关的全固态纳秒脉冲发生器和具有针环电极结构的等离子体射流装置组成。其中,纳秒脉冲源主要由直流电源、控制电路和主电路组成,主电路为10级模块化设计的Marx电路,使用MOSFET作为主开关和尾切开关;控制电路产生同步触发脉冲信号,通过光纤进行隔离后同步驱动MOSFET工作。输出纳秒脉冲电压参数为:幅值0~8k V可调,脉宽100~1 000ns,重复频率1Hz~1k Hz,上升沿30ns左右,下降沿50ns以内。等离子体射流装置使用氩气作为工作气体,其结构为针-环电极结构。搭建等离子体射流实验平台,并能够产生稳定的等离子体,为进一步探索大气压等离子射流的应用奠定了基础。     

改进电声脉冲法的交流空间电荷测量新方法

提出一种交流电压下的电声脉冲法空间电荷测试新方法。采用电脉冲作为触发源,利用数字示波器的长存储功能同时获取空间电荷信号和高压交流电压信号,从而避免了传统交流空间电荷测试方法的硬件同步。通过调整脉冲发生器的频率可获取不同相位下的高压交流下的空间电荷响应,并通过平均若干个交流周期的空间电荷信号获得足够信噪比的相位相关的空间电荷信号。通过对低密度聚乙烯工频50 Hz下的空间电荷测量结果表明,在交流电场下,下电极附近区域会形成异号电荷;与传统的交流空间电荷测量系统相比,由于测量时间得到很大程度缩短空间电荷信息能够最大限度保存,并且新系统较老系统有更高的相位分辨率,空间电荷衰减图形更能逼真的反映电荷动态变化。     

陡脉冲不可逆性电击穿治疗肿瘤的研究

为寻求更为有效的肿瘤治疗策略,通过对陡脉冲治疗肿瘤的电穿孔效应和内处理效应的国内外研究现状的分析,提出了陡脉冲不可逆性电击穿效应调控肿瘤细胞死亡和凋亡的创新思路。实验中肉眼和组织学、超微结构的观察首次证实陡脉冲能有效地杀伤肿瘤细胞,明显抑制了肿瘤的生长、增殖,延长了的生存期。基于重庆大学的最新研究提出了不同窗口参数的陡脉冲具有不同的生物电效应的设想,总结了利用陡脉冲不可逆性电击穿效应治疗肿瘤的新方法及目前的研究进展并提出了该技术走向临床需重点研究的内容及关键技术。     

场畸变火花开关电极优化设计及其触发特性

在烟气脱硫脉冲电源中采用场畸变火花间隙为开关,并在探讨开关电极各种形状基础上以旋转椭圆近似法优化设计一近似Ｂｏｒｄａ 电极形状为开关主电极形状,实验研究表明它触发性能可靠,可实现低脉冲幅值触发,且其放电点分布均匀,大大减小了电极烧损,有利于延长开关寿命     

A Flat Interface Nerve Electrode With Integrated Multiplexer

One of the goals of peripheral nerve cuff electrode development is the design of an electrode capable of selectively activating a specific population of axons in a common nerve trunk. Several designs such as the round spiral electrode or the flat interface nerve electrode (FINE) have shown such ability. However, multiple contact electrodes require many leads, making the implantation difficult and potentially damaging to the nerve. Taking advantage of the flat geometry of the FINE, multiplexers were embedded within the cuff electrode to reduce the number of leads needed to control 32 channels. The circuit was implemented on a polyimide film using off-the-shelf electronic components. The electronic module was surface-mounted directly onto the electrode's flat substrate. Two circuit designs were designed, built, and tested: (1) a single supply design with only two wires but limited to ca- thodic-first pulse and (2) a dual-supply design requiring three lead wires but an arbitrary stimulation waveform. The electrode design includes 32 contacts in a 1 mm x 8 mm opening. The contact size is 300 mum x 400 mum with access resistance less than 1 kOmega. This electrode is not intended for long-term use, but developed as a feasibility study for future development using low-water-absorption materials such as liquid crystal polymer and an application specific integrated circuit.     

一种可控恒流脉冲刺激器设计

为满足术中神经监测系统中运动诱发电位刺激器的设计需求,设计了一种可控恒流脉冲刺激器。采用2个基于UC3845的反激式开关电源产生所需电压,IGBT作为总开关管控制脉冲发放,三极管控制电路实现恒流。刺激器的特点是输出脉冲参数调节范围大、输出档位多、控制精度高、响应速度快而且档位多。当所有设置完成后,刺激器能在100ms内实现脉冲发放,最大输出脉冲幅度为100mA,脉冲各参数相对误差都小于5%。测试结果表明,刺激器各项指标都达到了设计要求,该刺激器也可用于其他需要输出恒流脉冲的场合。     

一种超宽带窄脉冲信号发生器的设计

宽度窄、幅度大的脉冲生成是探地雷达系统中要解决的关键问题之一.本文在比较了几种不同实现电路的优缺点,详细分析了雪崩三极管原理的基础,提出利用雪崩三极管的雪崩特性,实现超宽带、窄脉冲的生成.文中给出了电路原理图和实验结果,电路分为正、负脉冲2部分,可生成底宽为纳/亚纳秒级、正、负脉冲的峰-峰值高达160 V的窄脉冲信号,并且脉冲拖尾的振荡起伏小,很好地满足了雷达系统的宽度窄、幅度大的要求.电路结构简单、参数可调、移植性强、适用范围广.     

Asynchronous delay doubler and binary low‐pass filter for a time‐delay chaotic circuit

In this paper, an asynchronous digital circuit is introduced for increasing the amount of delay in binary delay lines in an area efficient way. The circuit that uses its slave delay line twice per delay event is called asynchronous delay doubler (ADD). The delay increases exponentially, while the number of components increases linearly in the recursive utilization of ADD. An assumption on the event interval of the input 2signal helps to design the ADD in a very simple form. Therefore, the ADD can be implemented with a small amount of logical resource (gates or look‐up tables). For proper operation, interval between the events (positive edge or negative edge) on the binary input signal should be larger than the delay provided by the recursive ADD block. In order to satisfy this assumption, an auxiliary asynchronous circuit, which is called binary low‐pass filter (BLPF), is also proposed. The BLPF filters out the pulses narrower than the delay generated by its recursive ADD block. The proposed ADD design is suitable especially for the applications, like random number generation, in which the deviation in amount of delay is useful as an entropy source. In order to prove the concept, a chain of recursive ADD block is implemented with BLPFs on a field‐programmable gate array and utilized in a true random bit generator. Copyright © 2015 John Wiley & Sons, Ltd.     

基于行波法的民用电力线路故障测距技术

民用电力系统具有分支线路多、折反射复杂、反射行波信号较弱、故障行波信号难以捕捉和识别的特点,为了实现对民用电力线路的故障定位,本文提出了一种利用分支线路检测装置+主机接收装置+低压脉冲发生器的故障定位方法,分支线路检测装置可以检测各分支线路的状况并在故障发生时将故障信息发送给主机接收装置,主机接收装置可以在电脑界面上显示相应的故障信息和位置,低压脉冲发生器用于离线测量、提高测距精度,该套装置配合通用行波测距装置可以实现对民用电力线路故障的准确定位。     

Functionally selective peripheral nerve stimulation with a flat interface nerve electrode

One of the important goals of peripheral nerve electrode development is to design an electrode for selective recruitment of the different functions of a common nerve trunk. A challenging task is gaining selective access to central axon populations. In this paper, a simple electrode that takes advantage of the neural plasticity to reshape the nerve is presented. The flat interface nerve electrode (FINE) reshapes the nerve into a flat geometry to increase the surface area and move central axon populations close to the surface. The electrode was implanted acutely on the sciatic nerve of eight cats. The FINE can significantly reshape the nerve and fascicles (p<0.0001) while maintaining the same total nerve cross-sectional area. The stimulation thresholds were 2.89 nC for pulse amplitude modulation and 10.2 nC for pulsewidth modulation. Monopolar, square-pulse stimulation with single contacts on the FINE selectively recruited each of the four main branches of the sciatic nerve. Simultaneous stimulation with two contacts produced moments about the ankle joint that were a combination of the moments produced by the individual contacts when stimulated separately.     

Perceptual thresholds and electrode impedance in three retinal prosthesis subjects.

Three test subjects blind from retinitis pigmentosa were implanted with retinal prostheses as part of a FDA-approved clinical trial. The implant consisted of an extraocular unit that contained electronics for wireless data, power, and generation of stimulus current, and an intraocular unit that consisted of 16 platinum stimulating electrodes arranged in a 4 x 4 pattern within a silicone rubber substrate. The array was held to the retina by a small tack. The stimulator was connected to the array by a multiwire cable and was controlled by a computer based external system that allowed precise control over each electrode. Perception thresholds and electrode impedance were obtained on each electrode from the subjects over several months of testing. The electrode distance from the retina was determined from optical coherence tomography imaging of the array and retina. Across all subjects, average thresholds ranged from 24-702 microA (1-ms pulse). The data show that proximity to the retina played a role in determining the threshold and impedance, but only for electrodes that were greater than 0.5 mm from the retina.