【作者】 刘青峰；

【导师】 张流强；

【作者基本信息】 重庆大学 ， 光学工程， 2009， 硕士

【摘要】 视觉诱发电位是视网膜受到刺激后在大脑视皮质产生的生物电活动,它能探测视路中从视网膜到视皮质的功能性损伤。视觉诱发电位检查技术具有非损伤性、客观性、定性、定量、可重复性的特点,在眼科疾病的诊断和鉴别中具有重要作用。由于研究视觉诱发电位的需要,针对视觉诱发电位测量系统的研究和开发具有重要的意义。视觉诱发电位属低频、微弱信号,测量过程中易受到强的背景噪声和干扰的影响,信号的放大成为了视觉诱发电位测量和分析中最为关键的环节。本文从介绍视觉诱发电位的特性出发,分析了用生物电极提取视觉诱发电位的等效电路模型,研究了来自系统内部噪声和外部干扰对视觉诱发电位测量的影响,探讨了高源阻抗微弱信号测量的影响因素,分析了元器件的分散性对电路性能的影响,利用保护、右腿驱动、隔离等技术设计了低噪声、高共模抑制比的视觉诱发电位放大电路系统,用ORCAD/PSpice软件对所设计的电路进行了仿真验证,以微控制器LPC2148作为控制单元设计了数据采集与控制系统,设计了VEP测量电路系统的印刷电路板,最后以图像翻转刺激方式对所设计的电路系统展开了实验,记录出了人体的图像翻转视觉诱发电位。实验结果表明,VEP测量系统的增益范围:10 000~200 000,带宽:1~300Hz,短路等效输入噪声峰峰值范围:2~4μV ,共模抑制比:106.7dB,经过64次叠加平均,成功测试出了人体的视觉诱发电位。更多还原

【Abstract】 Visual Evoked Potentials (VEPs) are produced by electrical activity of the visual cortex in response to light or pattern stimulation of the retina. It can detect functional loss in the visual pathway from retina to the visual cortex. VEP examination is a nondestructive, objective, qualitative, quantitative and repeatable measurement; it is the influential role to the visual disease diagnosis and distinction. For study of VEP, it is vital significance to research and develop VEP measurement system.Vision evoked potentials are low frequency and weak signal, measurement for VEP are subject to strong background noise and interference. Amplification is the most critical step in measuring and analyzing VEP. This paper has presented the principle and characteristic of VEP, analyzed the equivalent circuit model of VEP with picked up by bioelectrode, researched the internal noise and external interference to influence on the outcome of VEP, discussed the influencing factor for high impedance weak signal measurement, analyzed the device’s value deviation from normal to influence the circuit performance, designed a low noise and high CMRR amplification circuit with guarding, driven right led circuit, isolation etc, simulated the circuit system using ORCAD/PSpice simulation software, designed the data acquisition and control system with microcontroller LPC2148, and designed the printed circuit board of measurement system. Finally, performed the experiment by pattern reversal stimulation, and recorded the results of pattern reversal VEP.The experimental results show that the VEP measurement system performance is that gain is 10 000~200 000, bandwidth is 1~300Hz, short-circuits equivalent input noise voltage peak-peak value is 2~4μV, CMRR is 106.7dB. It is undergoes 64 averaging be able to succeed recording VEP.更多还原