用于测量介电常数的叉指电容传感器设计

Design of interdigital capacitive sensor for measuring dielectric constant

为实现保持一定精度的低成本测量样品介电常数,提出了一种改良型叉指电容传感器结构和便捷的测量方法。通过传感器模型和测量电路的设计与仿真,借助极间电容建立了归一化输出信号电压幅度与介电常数的线性关系,提供了通过归一化输出电压幅度得出介电常数的便捷方法。在无需严格限制待测材料尺寸的情况下,仿真结果表明:该传感器和测量方法可对材料实现快速测量。实际校准和测量表明:对于相对介电常数在5.6以下的材料,本文传感器和方法可实现相对误差小于3%的介电检测,且具有测量便捷、成本低、尺寸小的特点。

In order to measure the dielectric constant of samples at a low cost and with a certain precision,an improved interdigitated capacitive sensor structure and a convenient measurement method are proposed.Through the design and simulation of the sensor model and measuring circuit,the linear relationship between the normalized output voltage amplitude of the signal and dielectric constant is established with the help of capacitor between electrodes,which provides a convenient method to obtain dielectric constant by normalized output voltage amplitude.The simulation results show that the sensor and the measurement method can be used to measure the material rapidly without strict limitations on the size of the material to be measured.The actual calibration and measurement show that for materials with a relative dielectric constant below 5.6,the sensor and the method can achieve dielectric detection with a relative error of less than 3%,and have the characteristics of convenient measurement,low cost,and small size.