共查询到20条相似文献,搜索用时 15 毫秒
1.
Liang D.H. Kovacs G.T.A. Storment C.W. White R.L. 《IEEE transactions on bio-medical engineering》1991,38(5):443-449
The scale of stimulating electrodes possible for use in functional electrical stimulation to restore motor and sensory function is rapidly approaching that of individual neurons. Although the electrodes may approach the dimensions of single nerve cells, it is unclear if the region of excitation elicited by each electrode will be correspondingly small. Previous techniques for evaluating this have either been tedious or have lacked the resolution necessary. This paper describes a method that uses the refractory interaction of the compound action potentials elicited by a stimulus pulse pair, along with high-resolution recording of those potentials, to achieve measurements of the selectivity of stimulation down to the scale of a few axon diameters. The feasibility of this technique is demonstrated in sciatic nerves of frogs (Rana Catesbiana) acutely implanted with a sapphire electrode array. 相似文献
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Miyoshi S Shimizu S Matsushima J Ifukube T 《IEEE transactions on bio-medical engineering》1999,46(4):451-460
We have proposed the tripolar electrode stimulation method (TESM) for narrowing the stimulation region and continuously moving the stimulation site for cochlear implants. The TESM stimulates the auditory nerve array using three adjacent electrodes which are selected among the electrodes of an electrode array within the lymphatic fluid. Current is emitted from each of the two lateral electrodes and received by the central electrode. The current received by the central electrode is made equal to the sum of the currents emitted from the lateral electrodes. In this paper, we evaluate whether or not TESM works according to a theory which is based on numerical analysis using an electrical equivalent circuit model of the auditory nerve fibers. In this simulation, the sums of the excited model fibers are compared to the compound action potentials (CAP's) which we obtained through animal experiments. To identify the main parameter while maintaining the amplitude of the CAP (the sum of the fired fibers), we assumed the presence of some parameters from the radial current density profile. In the case of the width value among the parameters being kept constant, the amplitude of the CAP was almost constant; thus, the number of the fired fibers was also almost constant. The width value equals the distance between the points at which the profile of the radial current density of the electrode array and the line of the radial threshold current density of the electrode array intersect. It is possible to determine the measure of the stimulation region or site by controlling the width value and the ratios of the currents emitted from the lateral electrodes. As a result, we succeeded in narrowing the stimulation region by controlling the sum of the currents emitted from the two lateral electrodes. Also we succeeded in continuously moving the stimulation site by modifying the currents emitted from the two lateral electrodes. 相似文献
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Kawamura K. Deai H. Sakamoto H. Yano T. Hamaguchi I. Takayama S. Nagatake Y. Tachimori M. Matsumura A. 《Electron Devices, IEEE Transactions on》2001,48(2):307-315
The integrity of gate oxides on low-dose separation by implanted oxygen (SIMOX) substrates fabricated by the internal-thermal-oxidation (ITOX) process, so-called ITOX-SIMOX substrates, was evaluated, and the influence of test device geometry on the characterization was investigated. Characterization of time-dependent dielectric breakdown (TDDB) was performed for a gate oxide of 8.6-nm thick using lateral test devices. Experimental results show considerable influence of gate electrode geometry on the gate oxide integrity (GOI) characteristics. This can be explained by a model that includes a lateral parasitic resistance in the superficial Si layer beneath the gate electrode. Based on analysis using this model, a test device with a small gate array was proposed to reduce the influence of lateral parasitic resistance, and the advantage of the device was verified 相似文献
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Electrical extracellular stimulation of peripheral nerve activates the large-diameter motor fibers before the small ones, a recruitment order opposite the physiological recruitment of myelinated motor fibers during voluntary muscle contraction. Current methods to solve this problem require a long-duration stimulus pulse which could lead to electrode corrosion and nerve damage. The hypothesis that the excitability of specific diameter fibers can be suppressed by reshaping the profile of extracellular potential along the axon using multiple electrodes is tested using computer simulations in two different volume conductors. Simulations in a homogenous medium with a nine-contact electrode array show that the current excitation threshold (Ith) of large diameter axons (13-17 microm) (0.6-3.0 mA) is higher than that of small-diameter axons (2-7 microm) (0.4-0.7 mA) with 200-microm axon-electrode distance and 10-micros stimulus pulse. The electrode array is also tested in a three-dimensional finite-element model of the sacral root model of dog (ventral root of S3). A single cathode activates large-diameter axons before activating small axons. However, a nine-electrode array activates 50% of small axons while recruiting only 10% of large ones and activates 90% of small axons while recruiting only 50% of large ones. The simulations suggest that the near-physiological recruitment order can be achieved with an electrode array. The diameter selectivity of the electrode array can be controlled by the electrode separation and the method is independent of pulse width. 相似文献
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The construction of an implantable electrode pair suitable for recording spontaneous multiple fiber activity in intact small nerves is described. Fabrication of the electrodes is not difficult, and implantation is straightforward and causes little nerve trauma. These electrodes give good signal/noise ratio, and are stable over several hours. They allow the experimenter to move the animal during recording. 相似文献
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An advanced multiple channel cochlear implant 总被引:4,自引:0,他引:4
An advanced multiple channel cochlear implant hearing prosthesis is described. Stimulation is presented through an array of 20 electrodes located in the scala tympani. Any two electrodes can be configured as a bipolar pair to conduct a symmetrical, biphasic, constant-current pulsatile stimulus. Up to three stimuli can be presented in rapid succession or effectively simultaneously. For simultaneous stimulation, a novel time-division current multiplexing technique has been developed to obviate electrode interactions that may compromise safety. The stimuli are independently controllable in current amplitude, duration, and onset time. Groups of three stimuli can be generated at a rate of typically 500 Hz. Stimulus control data and power are conveyed to the implant through a single transcutaneous inductive link. The device also incorporates a telemetry system that enables electrode voltage waveforms to be monitored externally in real time. The electronics of the implant are contained almost entirely on a custom designed integrated circuit. Preliminary results obtained with the first patient to receive the advanced implant are included. 相似文献
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Nishino T. Hatano M. Hasegawa H. Murai F. Kure T. Hiraiwa A. Yagi K. Kawabe U. 《Electron Device Letters, IEEE》1989,10(2):61-63
A superconducting field-effect transistors (FET) with a 0.1-μm-length gate electrode was fabricated and tested at liquid-helium temperature. Two superconducting electrodes (source and drain) were formed on the same Si substrate surface with an oxide-insulated gate electrode by a self-aligned fabrication process. Superconducting current flowing through the semiconductor (Si) between the two superconducting electrodes (Nb) was controlled by a gate-bias voltage 相似文献
10.
Parrillo L.C. Pfiester J.R. Woo M.P. Roman B. Ray W. Ko J. Gunderson C. 《Electron Device Letters, IEEE》1991,12(10):542-545
The concept of using LDD spacers that are independently biased with respect to the gate electrode is presented. It is shown that the lateral electric field is strongly influenced by the drain polysilicon spacer potential. Depending on the N- dose, the peak substrate currents can be either enhanced or reduced by shorting the drain polysilicon spacer to the drain potential. Short-channel LDD MOSFETs have been fabricated with polysilicon LDD spacers shorted to the source and drain electrodes by titanium silicide 相似文献
11.
Salme Jussila Maria Puustinen Tomi Hassinen Juuso Olkkonen Henrik G.O. Sandberg Kimmo Solehmainen 《Organic Electronics》2012,13(8):1308-1314
We present a new manufacturing method for the bottom-gate type organic field-effect transistor (OFET) having a self-aligned gate electrode based on conducting poly(aniline). This method utilizes the possibility to turn the insulating emeraldine base (PANI-EB) form of poly(aniline) into the conducting emeraldine salt (PANI-ES) form by using UV exposure and photoacid generator (PAG) material. When the source–drain electrodes are used as the mask layer in the UV exposure step an optimal alignment between the gate electrode and source–drain electrodes can be reached, and the parasitic capacitance of the transistor can be minimized. We anticipate that the proposed concept also simplifies the fabrication of the transistors since no additional processing of the photoresist layers is needed to pattern the gate electrode or the gate insulator layer. 相似文献
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Sensitivity and selectivity of intraneural stimulation using a silicon electrode array 总被引:2,自引:0,他引:2
Rutten W.L.C. van Wier H.J. Put J.H.M. 《IEEE transactions on bio-medical engineering》1991,38(2):192-198
Artificial electrical stimulation of peripheral nerves needs the development of multielectrode devices which stimulate individual fibers or small groups in a selective and sensitive way. To this end, a multielectrode array in silicon technology has been developed, as well as experimental paradigms and model calculations for sensitivity and selectivity measures. The array consists of twelve platinum electrode sites (10 x 50 microns at 50 microns interdistance) on a 45 microns thick tip-shaped silicon substrate and a Si3N4 insulating glass cover layer. The tip is inserted in the peroneal nerve of the rat during acute experiments to stimulate alpha motor fibers of the extensor digitorum longus muscle. Sensitivity calculations and experiments show a cubic dependence of the number of stimulated motor units on current amplitude of the stimulatory pulse (recruitment curves), starting at single motor level. Selectivity was tested by a method based on the refractory properties of neurons. At the lowest stimulus levels (for one motor unit) selectivity is maximal when two electrodes are separated by 200-250 microns, which was estimated also on theoretical grounds. The study provides clues for future designs of two- and three-dimensional devices. 相似文献
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Enhanced Charge Injection Through Nanostructured Electrodes for Organic Field Effect Transistors
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Nanosphere lithography is used to process nanopore‐structured electrodes, which are applied into the fabrication of bottom‐gate, bottom‐contact configuration organic field effect transistors (OFETs) to serve as source/drain elecrodes. The introduction of this nanopore‐structure electrode facilitates the forming of nanopore‐structure pentacene layers with small grain boundaries at the electrode interface, and then reduces the contact resistance, contact‐induces the growth of pentacene and accordingly improves the mobility of charge carriers in the OFETs about 20 times as compared with results in literature through enhancing the charge carrier injection. It is believed that this structure of electrode is a valuable approach for improving organic filed effect transistors. 相似文献
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Pan J. Woo C. Ngo M.-V. Chih-Yuh Yang Besser P. King P. Bernard J. Adem E. Tracy B. Pellerin J. Qi Xiang Ming-Ren Lin 《Electron Devices, IEEE Transactions on》2003,50(12):2456-2460
This letter reports the first replacement (Damascene) metal gate pMOSFETs fabricated with Ni/TaN, Co/TaN stacked electrode, where Ni or Co is in direct contact with the gate SiO/sub 2/, to adjust the electrode metal work function and TaN is used as the filling material for the gate electrode to avoid wet etching and CMP problems. The process is similar to the fabrication of traditional self-aligned polysilicon gate MOSFETs, except that in the back end (after the source/drain implants are activated) a few processing steps are added to replace the polysilicon with metal. Our data show that the Ni or Co/TaN gate electrode has the right work function for the pMOSFETs. The metal gate process can reduce the gate resistivity. Thermal stability of the stacked electrodes is studied and the result is reported in this paper. The damascene process flow bypasses high temperature steps (> 400/spl deg/C)critical for metal gate and hi k materials. This paper demonstrates that a low temperature anneal (300/spl deg/C) can improve the device performance. In this paper, the gate dielectrics is SiO/sub 2/. 相似文献
18.
Insulated-gate field-effect transistors have been made, which combine the advantages inherent to Schottky barrier source and drain electrodes with ion implantation. This device has a self-aligned gate structure achieved by using the thick gate electrode as a mask during the ion implantation process. 相似文献
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Nitayama A. Takato H. Okabe N. Sunouchi K. Hieda K. Horiguchi F. Masuoka F. 《Electron Devices, IEEE Transactions on》1991,38(3):579-583
The M-SGT has a three-dimensional structure, which consists of the source, gate, and drain arranged vertically. The gate electrode surrounds the crowded multipillar silicon islands. Because all the sidewalls of the pillars are used effectively as the transistor channel, the M-SGT has a high-shrinkage feature. The area occupied by the M-SGT can be shrunk to less than 30% of that occupied by the planar transistor. The small occupied area and the mesh-structured gate electrode lead to the small junction capacitance and the small gate electrode R C delay, resulting in high-speed operation. The fabrication of the M-SGT CMOS inverter chain is discussed. The propagation delay reduces to 40%, compared with the planar transistor inverter chain 相似文献
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双CMOS仿生3D视觉传感器电路设计 总被引:1,自引:1,他引:0
针对目前3D相机中出现的图像数据易丢失、左右图像同步难等问题,提出一种可精确采集左右格式立体对图像的仿生3D传感器实现方法,可为仿生3D传感器的光路系统的检验及目标物三维重建提供精确三维坐标信息。为更好协调3D传感器在光信号处理中的点像素同步,采用现场可编程门阵列处理双OV3640图像传感器各信号,初始化后在像素时钟的准确控制下采集图像数据并完成输出图像格式转换、缓存、左右格式立体对图像拼接及输出显示验证。结果表明,3D传感器工作可靠、集成度高、体积小,可精确采集左右格式立体对图像。 相似文献