【摘要】 目的为获得电信号刺激神经纤维时的动作电位,本文设计了一种电诱发复合动作电位测量系统,解决了诱发动作电位的精确采集问题,有效去除了本底噪声的影响。方法分析了范围在十几微伏的电诱发复合动作电位到几十毫伏电极电位测量时存在的难点,以及一个测量系统正常工作时需要满足的测量放大器共模容限和差模容限及电流源电压容限问题。基于此,本文提出采用3级运算放大器级联的方式实现诱发动作电位的采集。系统主要由3级级联放大器、自动零点调整环节和基准电压部分组成,实现对弱信号的放大、消除本底噪声和提供过压保护。结果采用本文设计的系统,测量得到11 m V的蛙类坐骨神经干复合动作电位和17μV的豚鼠耳蜗电诱发复合动作电位,验证了本系统可有效测量各种诱发电位。结论采用3级放大器级联的方式和自动零点跟踪方式解决了微弱信号的有效放大和精确采集技术,为进一步研究通过电信号直接刺激神经纤维所产生的动作电位的特性提供可靠的测量手段。更多还原

【Abstract】 Objective When the nerve fiber is stimulated by the electrical pulse,there is an evoked compound action potential which indicates the synchronism property of the nerve fiber. In order to obtain the precise action potential,a measuring system of evoked compound action potential is presented in this paper.The system can collect the compound action potential precisely and eliminate the effect of ground noise.Methods Firstly,we analyzed the difficulty in the measurement of the compound action potential which ranged from μV level to the m V level. Secondly,we discussed the common-mode tolerance,differential mode tolerance and the voltage margin of the electric current which guaranteed the proper functioning of the measuring system.Based on the issues,we proposed a measuring system of compound action potential which was realized by the operational amplifier using 3-cascade methods. The system consisted of 3-cascade,automatic zero tracking and reference voltage. In this system,the amplification of the weak signal was realized and the background noise was eliminated effectively. Contemporarily,the system provided the efficient overvoltage protection. Results The compound action potential of the frog sciatic nerve which was only 11 m V and the electrically evoked compound action potential of guinea pig which was 17 μV were measured by this system. The experimental results showed that the accurate compound action potential could be obtained by this measuring system. Conclusions The 3-cascade structure and automatic zero tracking mightbe an effective way for the effective amplification and precise measurement of small signals. This system supplies a stably measuring method for the further research on the special property when the electrical signal stimulates the nerve fiber directly.更多还原