基于膜片钳的微压力控制系统.docxVIP

摘要膜片钳技术作为电生理研究的有力工具，广泛用于细胞膜离子通道电流的测量,细胞分泌，药理学，病理生理学，神经科学，脑科学，细胞生物学与分子生物学研究以及植物细胞的生理研究等。在膜片钳实验中，吉欧封接的形成是至关重要的步骤，一般通过电极与电极夹持器内腔气体压力来完成。目前通常是以人工吹吸来进行，主要存在以下问题：用人工吹吸得到气体压力值凭的是经验值，无法精确计算；人工吹吸提供的负压不能稳定持续。封接中往往因为负压不足而对细胞再次进行吸附，影响封接的质量和效率；人工吹吸方法无法实现膜片钳实验中吉欧封接的自动控制，难于实现后续膜片钳实验的自动控制和对细胞的高通量检测。本文介绍了一种基于膜片钳实验的微压力控制系统[3]。本文先对气压信号的特性进行分析，给出气压采集设备的性能要求和技术指标。然后根据指标要求确定系统的整体设计方案，这其中包括对关键元器件的选型及理论上的可行性分析。本文设计部分分为气路控制和电路控制来介绍。其中气路部分硬件关键元件为：电磁阀、气泵电机和气压传感器。电路控制部分包括气压信号采集模块、CPU外围电路模块、光耦隔离模块、电机驱动模块、电源管理模块、液晶显示模块和串口通讯模块。微压力控制系统是基于C8051F020单片机的闭环控制系统，该系统的基本工作原理为：由压力传感器实时采集气压值反馈给单片机，与预定值进行比较，根据对比结果，单片机通过脉冲宽度调制控制气泵电机的转速，从而调整电极内气压使其达到预测值；单片机能与上位机进行串行通信，实时将数据同步到电脑，并通过Labview平台控制下位机系统的运行，同时上位机软件还兼有波形显示和数据存储的功能。关键词：膜片钳；微压力控制；单片机；脉冲调制AbstractThe patch clamp as a powerful tool has seen the largest number of applications in the recording of channels ion currents embedded in the cell membrane, cellular secretion, pharmacology, pathological physiology, neuroscience, brain research, cellular and molecular biology as well as the physiological study of plant cells, etc.The formation of giga-ohm seal is an important step in the patch clamp experiment, which is usually realized by controlling the air pressure within pipette and the holder. Nowadays, the process is usually performed with artificial blowing and inhaling bring out some inevitable problems. Firstly, the value of manually obtained air pressure is just based on the operations’ individual experiences, resulting in the inaccuracy of the calculation of value. Secondly, the pressure supported by artificial blowing and inhaling is unstable, while the adsorption to cell often need to several times due to the inadequacy of the in-pipette negative pressure, affecting the quality and efficiency. Thirdly, the method of artificial blowing and inhaling for sealing makes it impossible to achieve the auto-control of the pressure used in the experiment of patch clamp.In the first section，we analyzed the features of pneumatic pressure and calculated the fundame