三电极差分电容式PCB用于通道内流体空隙率检测

摘要

To solve the fluid void ratio detection problem in airtight channel,such as blood vessel an d oil pipeline,a three electrode differential capacitance detection method is proposed. The method was designed and realized based on capacitor printed circuit board (PCB). When the air bubbles and other voids exist in the airtight channel,the capacitance of the sensor will change. Based on this principle,the differential capacitor amplifier,phase locked amplifier,filter and a data acquisition card are used to monitor the capacitance changes,the copper structure from top to bottom of the PCB surface is selected as the elec⁃trode,and the plastic tube is laid vertical to PCB surface through the capacitance sensor. Since the fluid′s void volume can ef⁃fect on the output voltage,the bubbles inside the liquid can be detected according to the signal imbalance between the three electrode potential voltage. The detected capacitance change signal is processed and calculated on computer to obtain the data of void volume and velocity. This fluid sensor can be used for void ratio detection in medical facilities.%为解决血管、输油管道等密闭通道内流体空隙检测问题，提出一种三电极差分电容式检测方法，该方法是基于电容器印刷电路板（PCB）进行设计实现。当空气泡等空隙存在于密闭通道时，传感器的电容会因此发生变化。基于此原理，利用差分电容放大器、锁相放大器、滤波器和一个数据采集卡进行电容变化的监测，电极采用自印刷电路板表面顶部至底部的铜质结构，塑料管通过电容传感器布局并垂直于印刷电路板表面。流体空隙体积会对输出电压产生影响，根据三电极电位电压间信号的不平衡，检测出液体内部气泡，并在计算机上对检测到的电容变化信号进行处理和计算，获取空隙体积、运动速度等数据。这种流体传感器也可用于医疗设备中空隙率检测。