【作者】 饶程；

【导师】 袁祥辉；

【作者基本信息】 重庆大学 ， 仪器科学与技术， 2006， 博士

【摘要】 目前,基于神经电刺激的人工视觉功能修复技术已成为人工器官领域的研究热点之一。根据刺激位置的不同,人工视觉功能修复可分为视皮层修复(Cortical Prosthesis)、视神经修复(Optic Nerve Prosthesis)和视网膜修复(Retinal Prosthesis)三大类。相比较而言,视皮层修复和视神经修复两种方式需将刺激电极阵列植入大脑皮层或视神经区域,手术复杂性和风险性较大。视网膜修复技术自从Humayun等人首次提出以来,已经历了十多年的发展,并且研究方案主要分为两种类型:表层型视网膜修复(Epiretinal Prosthesis)和外层型视网膜修复(Subretinal Prosthesis)。外层型视网膜修复技术将刺激器件植入在视网膜神经感觉上皮和色素上皮层之间的区域(Subretinal Place),首先刺激的是外层视网膜表面,因此可以利用更多的受损视网膜中存活的细胞对视觉信号进行处理,并使电流刺激阈值降低,本质上具有突出的优势。国外对各种人工视觉功能修复技术都进行了很深入的研究,特别是美国的第二视觉公司(Second Sight)和光学仿生学公司(Optobionics)已经分别将自己研究的人工视网膜芯片植入盲患眼中进行临床实验。相对于我国庞大的盲患人群,国内人工视网膜技术的研究起步较晚。针对目前外层型视网膜修复技术需要在眼外提供很强照明的不足,本文在自然科学基金项目(No.30470469)资助下,在电路层次上进行适用于自然光照条件的外层型CMOS人工视网膜微芯片的研究。论文首先介绍了人工视觉功能修复技术的概念、分类及特点,综述了国际上在这一领域的研究现状,并分析了人工视觉修复技术的发展方向。总结和分析了进行外层型CMOS人工视网膜微芯片设计的理论和实验依据,包括神经细胞电刺激产生动作电位的原理、视网膜细胞电刺激的有效性、安全性、刺激阈值、刺激电极材料以及电极-视网膜界面的电性能等。针对目前外层型人工视网膜修复技术的不足,提出了一种在自然光照条件下用于外层型视网膜电刺激的光控CMOS振荡像元结构。新方案中光电探测器工作在积分工作模式,利用光电流控制像元上电容的放电过程,实现像元输出脉冲频率随外界光强准线性变化。电路仿真结果表明,与国外振荡像元类方案相比,新方案具有像元结构简单和输出性能好的优点。光电探测器是光控CMOS振荡像元的信号源头,论文分析了目前与CMOS工艺兼容的光电探测器类型,并进行了性能比较。从半导体中载流子平衡方程出发,详细阐述了光电二极管感应光电流的过程及电流的计算模型,建立了光电二极管的PSPICE仿真模型。利用所建模型,对光控CMOS振荡像元电路进行了优化设更多还原

【Abstract】 Artificial visual functions recovery has attracted the most attention in the field of artificial organs. In general, there are three types of solutions according to the different positions of electrical stimulation, named cortical prosthesis, optic nerve prosthesis and retinal prosthesis. Cortical prosthesis and optic nerve prosthesis require more complicated operations and may bring more risks comparing with retinal prosthesis owing to implant in the cortical region and optic nerve place. Retinal prosthesis has been presented for over ten years by Humayun and actually developed in two different directions: epiretinal prosthesis and subretinal prosthesis. Subretinal prosthesis put the implant in subretinal space and meets first the outer retina. It can utilize more live retinal cells of blind patients to process vision information and decrease the current threshold of electrical stimulation, accordingly, possesses the essential advantages. Various artificial visual functions recovery technologies have been researched detailedly. Especially, Second Sight Corp. and Optobionics Corp. in USA have implanted their devices in the eyes of blind patients for clinical experiments. There are enormous blind patients in China, however, the research in this field is started relatively late. Since the present subretinal prosthesis solutions need extraocular illuminating equipments to enhance visual information, this dissertation developes a subretinal CMOS artificial retina microchip at the circuit level for normal light illumination under the support of NSFC (No.30470469).Firstly, this dissertation introduces the concept, classification and characteristics of artificial visual functions recovery technology. The research progresses in this fiels are reviewed and its development tendencies are analyzed. Then, the theoretic and experimental groundworks for design a subretinal CMOS artificial retina microchip are summarized, which include the principles of action potential generated by neuronal electrical stimulation, the effectivity, safety and threshold of retinal electrical stimulation, electrode material and the electric performances of electrode-retina interface.Aimed at the disadvantages of the present subretinal prosthesis, this dissertation proposes a light-control CMOS oscillating pixel structure for subretinal electrical stimulation under normal light illumination. In the novel solution, the photocurrent of photodetectors controles the discharge process of the pixel capacitor to realizes the更多还原