用于视觉假体的柔性生物微电极阵列的设计和制作

提出了一种用于视网膜假体的基于Parylene的柔性微电极阵列的设计和制作.微电极阵列为5×5,通过光刻胶热熔回流技术形成的电极点为半球形凸起,底部直径为60 μm,高度大约为24 μm.整个电极具有很好的柔韧性,能够更好的适应视网膜表面轮廓,提高刺激效果.同时,电极具有很好的透明性,便于手术时电极的植入和手术后对生物组织的观察.     

基于柔性衬底的人造视网膜生物微电极阵列研究

设计了一种用于刺激视网膜的生物微电极阵列,采用非硅MEMS技术,在聚酰亚胺柔性衬底上制备出了具有一定生物相容性的,电极数为20的生物刺激电极阵列,并成功实现了器件从基底的完整释放。实验中采用了二次曝光法,用金修饰了电极柱侧壁,从而提高了电极的生物相容性;采用PDMS作为柔性衬底与玻璃片的粘附层,使得器件的释放过程,简单且无毒无害,对器件也无损害。制造出的器件尺寸小,质量轻,可靠性高,机械柔性好。对微电极阵列进行了电学性能测试,在10~5000Hz频率范围,其阻抗为104~106欧姆,符合电刺激要求。     

基于直列式交错微电极阵列的细胞电融合

提出了一种基于交错式齿状微电极阵列的微流控细胞电融合芯片。利用COMSOL Multiphysics仿真软件,对电场强度有重要影响的微电极几何参数进行了仿真分析,并由此提出了优化的微电极阵列结构。选择SoI硅片的顶层低阻硅加工获得了微电极阵列。实验结果表明:该芯片中采用的直列式微通道结构避免了原有芯片存在的转角易堵塞问题。芯片能够在低电压条件下实现细胞排队和融合过程,具有较高的融合效率。     

利用喷墨打印技术制备的类神经气体传感器

利用喷墨打印技术沉积生物高分子溶液的方法,打印出金的梳状微电极的阵列图形,并采用NaX型沸石分子筛作为敏感膜,研制了探测神经类毒气沙林的相似物DMMP气体的阻抗型传感器。电极图形使用简单的绘图软件autoCAD画出,通过简单改进过的办公用喷墨打印机在金衬底上打印一层自组装膜的阻挡层,经过湿法刻蚀后得到了梳状微电极阵列。将制得的传感器对1ppm(即1×10-6)DMMP气体进行检测,测得在0.01Hz处,其电阻的相对变化值为10.7%。与传统MEMS工艺相比较,喷墨打印方法制备传感器具有工艺步骤简化,成本低,可在柔性等不同材料上制作等优点,有着广泛的应用前景。     

三维神经微电极阵列新制作技术研究

尝试了一种低成本的三维微电极阵列微加工的新方法.玻璃划片形成的柱状阵列,经掩膜腐蚀后形成阳模板,再利用PDMS的微复制技术形成阴模板.利用阴模板进行电镀,可以得到三维微电极阵列.制作的铜电极阵列高度约180 μm,为制作更长的神经微电极阵列打下了基础.     

基于柔性衬底的三维生物刺激微电极阵列研究

设计了一种基于聚酰亚胺薄膜的三维生物刺激微电极阵列,用于植入式人造视网膜应用.采用非硅MEMS技术,在柔性衬底上制备出具有生物相容性和化学稳定性,电极高度为80 μm的生物刺激电极阵列,通过PDMS牺牲层实现器件从基底的完整释放.实验中器件以聚酰亚胺和PDMS封装,电极柱和焊盘均镀金,从而提高电极的生物相容性.采用三电极法对微电极进行了电化学性能测试,在10-1～105Hz频率范围内,其阻抗为1.5～0.3 kΩ.制造出的器件尺寸小,质量轻,可靠性高,机械柔性好,符合生物电刺激要求.     

一种柔性三维力触觉传感器阵列的实现方法

介绍了一种可安装在曲面上,对三维力进行检测的柔性三维力触觉传感器阵列的实现方法.首先采用MEMS技术制备三维力触觉传感器阵列,再将多个三维力触觉传感器单元分别通过倒装焊技术集成在已加工好的柔性电路板基底上,实现了传感器与信号处理电路的互连和传感器阵列(4×4)的柔性化.采用信号选通的多路信号采集方法简化了传感器阵列的信号处理电路.测试结果表明,柔性触觉传感器阵列可弯曲变形90°以上,检测三维力的分辨率达到0.1 N.     

基于柔性微电极的高灵敏度MEMS电化学地震检波器

为了进一步降低微机电系统(MEMS)电化学地震检波器敏感电极的加工成本,提升传感器的灵敏度,推动其在地球物理勘探等领域的发展,提出了一种基于柔性微电极结构的新型MEMS电化学地震检波器.与基于硅衬底制作敏感电极相比,敏感电极的制作方法可以通过有效减小电极间距,大幅度提升传感器的灵敏度,大幅降低工艺成本.介绍了柔性微电极的加工工艺流程,并对传感器的性能进行了测试.结果表明:提出的地震检波器较基于硅衬底微电极器件灵敏度提高了一个数量级.     

用于微电极阵列和光同时记录的神经传感器平台设计

微电极阵列（MEA,Microelectrode Arrays）和光成像记录已成为从神经网络收集可靠数据的重要工具。然而，没有商业平台被设计用于微电极阵列和光成像的同时记录，由于商业平台的物理限制和高成本，无法对其进行定制。为了解决这个问题，开发了一个小体积的定制神经记录平台，它很容易集成到现有的显微镜环境中。该系统的特点是低输入参考噪声（<2μV）、紧凑的尺寸以及有同时执行微电极阵列和光成像记录的能力。使用该平台对微电极阵列上的神经元进行测量验证表明，该平台为研究钙动力学及其与神经元中动作电位的关系提供了有价值的工具。     

基于单壁碳纳米管的压阻式柔性传感器

一维纳米材料与微结构结合的纳器件制造过程,实现了微纳加工工艺上的创新升级,有可能突破微米级器件的性能极限。首先利用传统的硅微加工技术,在综合性能优异的聚酰亚胺PI(Polyimide)薄膜上制作金(Au)微电极,形成排列有序的平行电极对;然后通过交流介电电泳的方法在微电极对间实现单壁碳纳米管SWNTs(Single-Walled Carbon Nanotubes)一维定向排布;接着采用区域选择性电沉积技术定域沉积Au压覆SWNTs,改善SWNTs与电极的接触特性。最后,针对基于SWNTs的柔性微纳传感器进行了力电特性测试。结果表明:在环境温度为(23±5)℃,湿度为65±15%RH,0.1 V工作电压下,压阻因子约为443,精度约为5.16%。上述研究结果在柔性微纳器件的制作方面显示了一定的应用前景,为实现超微型化和高功能密度化的柔性器件铺平道路。     

Molecular detection based on the electrical conductance of gold nanoparticle arrays

We report a molecular sensing method based on changes in the electrical conductance of lithographically defined gold nanoparticle (NP) arrays immersed in an analyte solution. As the closely spaced NPs are enlarged due to the analyte-mediated deposition of gold ions onto their surfaces, the conductance increases steeply near the critical time (t_c) at which conducting pathways begin to form in the NP arrays. t_c decreases with increasing analyte concentration in the solution. The temperature dependence of the conductance of the modified NP arrays confirms the good electrical contacts established between the newly formed nanoclusters on the NP surfaces. Our results demonstrate that the electrical conductance through metal NP arrays can be employed as a sensitive and reliable analytical signal for NP-based sensors, which do not require any post-processing for the formation of electrical contacts between the NPs.     

Development of microfluidic device for electrical/physical characterization of single cell

A novel device with microchannels for flowing cells and twin microcantilever arrays for measuring the electrical impedance of a single cell is proposed. The fabrication process is demonstrated and the twin microcantilever arrays have been successfully fabricated. In our research, we measured the electrical impedance for normal and abnormal red blood cell over the frequency range from 1 Hz to 10 MHz. From the electrical impedance experiment of normal and abnormal red blood cell, it was examined that the electrical impedance between normal and abnormal red blood cells was significantly different in magnitude and phase shift. In this paper, we show that the normal cell can be taken apart from the abnormal cell by electrical impedance measurement. Therefore, it is expected that the applicability of this technology can be used in cellular studies such as cell sorting, counting or membrane biophysical characterization.     

Arrays of addressable contactless optical microshutters

The present paper describes the development of contactless optical microshutter arrays, which are mounted in an assembly of microlenses, optical fibers and driving electronics. In the past, complete systems have been made, for different applications, by using microshutters with contacting surfaces. We have been able to demonstrate the functionality of these complete devices, but in-use stiction limited their lifetime. The arrays also showed short-circuit due to shutters jumping over the electrodes, because of an asymmetrical electrical field distribution.Despite years of advancements in micromachining technologies, in-use stiction remains a fundamental issue in micro electro-mechanical systems (MEMS), resulting in device failure. Anti-stiction layers have been developed and even industrialized, but they require hermetically sealed devices or have a limited lifetime. A more drastic solution to solve in-use stiction and jump over is to resort to a device without any mechanical stopper. After having considered several solutions, we have designed, manufactured and successfully tested contactless shutters.     

Finite element modeling and experimental proof of NEMS-based silicon pillar resonators for nanoparticle mass sensing applications

The potential use of nanoelectromechanical systems (NEMS) created in silicon nanopillars (SiNPLs) is investigated in this work as a new generation of aerosol nanoparticle (NP)-detecting device. The sensor structures are created and simulated using a finite element modeling (FEM) tool of COMSOL Multiphysics 4.3b to study the resonant characteristics and the sensitivity of the SiNPL for femtogram NP mass detection in 3-D structures. The SiNPL arrays use a piezoelectric stack for resonance excitation. To achieve an optimal structure and to investigate the etching effect on the fabricated resonators, SiNPLs with different designs of meshes, sidewall profiles, heights, and diameters are simulated and analyzed. To validate the FEM results, fabricated SiNPLs with a high aspect ratio of approximately 60 are used and characterized in resonant frequency measurements where their results agree well with those simulated by FEM. Furthermore, the deflection of a SiNPL can be enhanced by increasing the applied piezoactuator voltage. By depositing different NPs [i.e., gold (Au), silver (Ag), titanium dioxide (TiO₂), silicon dioxide (SiO₂), and carbon black NPs] on the SiNPLs, the decrease of the resonant frequency is clearly shown confirming their potential to be used as airborne NP mass sensor with femtogram resolution level. A coupling concept of the SiNPL arrays with piezoresistive cantilever resonator in terms of the mass loading effect is also studied concerning the possibility of obtaining electrical readout signal from the resonant sensors.     

Low-cost microelectrode array with integrated heater for extracellular recording of cardiomyocyte cultures using commercial flexible printed circuit technology

This article reports the use of commercial, flexible printed circuit technology for the fabrication of low-cost microelectrode arrays (MEAs) for recording extracellular electrical signals from cardiomyocyte cultures. A 36-electrode array has been designed and manufactured using standard, two-layer, polyimide-based flexible circuit technology, with electrode diameters of 75 and 100 μm. Copper structures defined on the backside of the array have been used for low-power thermal regulation of the culture. Electrical characterization of the gold-plated electrodes showed impedances below 250 kΩ at 1 kHz. Functional testing was conducted using HL-1 cardiac myocytes. The arrays proved biocompatible, and supported the formation of functional syncytia, as demonstrated by electrical recordings of depolarization waves across the array. A comparison with conventional, glass-based MEAs is presented, which reveals differences in signal strength (smaller for larger electrode) and variability (less for larger electrodes), but no effect of the substrate types on culture parameters such as beat rate or conduction velocity. The performance of the on-chip heating was evaluated, with typical temperature settling times (to ±0.1 °C) below 10 s, for a power consumption around 1 W (at 37 °C). Accuracy and stability are discussed. HL-1 cell responses to various temperature profiles enabled by the on-chip heating are presented, showing a remarkable correlation between temperature and beat rate.     

Electrode array-based electrical stimulation using ILC with restricted input subspace

Electrode arrays are gaining increasing popularity within the rehabilitation and assistive technology communities, due to their potential to deliver selective electrical stimulation to underlying muscles. This paper develops the first model-based control strategy in this area, unlocking the potential for faster, more accurate postural control. Due to time-varying nonlinear musculoskeletal dynamics, the approach fuses model identification with iterative learning control (ILC), and employs a restricted input subspace comprising only those inputs deemed critical to task completion. The subspace selection embeds past experience and/or structural knowledge, with a dimension chosen to affect a trade-off between the test time and overall accuracy. Experimental results using a 40 element surface electrode array confirm accurate tracking of three reference hand postures.     

Implantable multichannel electrode array based on SOI technology

This work presents a new method of fabricating implantable multielectrode arrays on lightly doped single-crystal silicon. Such arrays are essential tools for electrical stimulation and recording of nerve signals. Our new microfabrication process, based on silicon-on-insulator (SOI) technology, inherently has excellent control over the final probe thickness without wet etching. The needle shanks are 6 mm long and 80 /spl mu/m wide. Here the thickness of the probe, 25 /spl mu/m, is defined by the device layer thickness on the SOI wafer. Our new sprinkler fluidic channel, which has holes spaced 50 /spl mu/m apart along its 6 mm length, permits the perfusion of a large area of tissue with any desired neurotransmitter or other drug. The probes fabricated here are tested in the cat primary visual cortex; data recorded from adjacent neurons was used to characterize their orientation tuning. The sprinkler channel was characterized, and flowrate through the channel is a linear function of the applied pressure.     

A polymer-based spiky microelectrode array for electrocorticography

The advanced technology of microelectromechanical systems (MEMS) makes possible precise and reproducible construction of various microelectrode arrays (MEAs) with patterns of high spatial density. Polymer-based MEMS devices are gaining increasing attention in the field of electrophysiology, since they can be used to form flexible, yet reliable electrical interfaces with the central and the peripheral nervous system. In this paper we present a novel MEA, designed for obtaining neural signals, with a polyimide (PI)—platinum (Pt)—SU-8 layer structure. Electrodes with special, arrow-like shapes were formed in a single row, enabling slight penetration into the tissue. The applied process flow allowed reproducible batch fabrication of the devices with high yield. In vitro characterization of the electrode arrays was performed with electrochemical impedance spectroscopy in lactated Ringer’s solution. Functional tests were carried out by performing acute recordings on rat neocortex. The devices have proven to be convenient tools for acute in vivo electrocorticography.     

某卫星电源系统仿真试验台下位机系统的设计

为验证和考核某卫星电源系统故障诊断专家系统的可行性和正确性 ,作者根据电源系统的工作原理 ,研制和开发了电源系统仿真试验台。本文主要从两部分来介绍该试验台下位机系统的设计方法 ,首先以太阳电池阵和损耗器为例 ,说明硬件模拟电路的设计方法 ,然后分析了单片机系统的硬件接口和软件设计方法。下位机系统的设计原理简单、功能可靠 ,能正确地模拟电源系统的正常与故障状态 ,为专家系统的验证提供充分的数据     

Efficient Index Set Generation for Compiling HPF Array Statements on Distributed-Memory Machines

In languages such as High Performance Fortran (HPF), array statements are used to express data parallelism. In compiling array statements for distributed-memory machines, efficient enumeration of local index sets and commmunication sets is important. A method based on a virtual processor approach has been proposed for efficient index set enumeration for array statements involving arrays distributed using block-cyclic distributions. The virtual processor approach is based on viewing a block-cyclic distribution as a block (or cyclic) distribution on a set of virtual processors, which are cyclically (or block-wise) mapped to the physical processors. The key idea of the method is to first develop closed forms in terms of simple regular sections for the index sets for arrays distributed using block or cyclic distributions. These closed forms are then used with the virtual processor approach to give an efficient solution for arrays with the block-cyclic distribution. HPF supports a two-level mapping of arrays to processors. Arrays are first aligned with a template at an offset and a stride and the template is then distributed among the processors using a regular data distribution. The introduction of a nonunit stride in the alignment creates “holes” in the distributed arrays which leads to memory wastage. In this paper, using simple mathematical properties of regular sections, we extend the virtual processor approach to address the memory allocation and index set enumeration problems for array statements involving arrays mapped using the two-level mapping. We develop a methodology for translating the closed forms for block and cyclically distributed arrays mapped using a one-level mapping to closed forms for arrays mapped using the two-level mapping. Using these closed forms, the virtual processor approach is extended to handle array statements involving arrays mapped using two-level mappings. Performance results on the Cray T3D are presented to demonstrate the efficacy of the extensions and identify various trade-offs associated with the proposed method.