导电介质交流阻抗测量的自由衰减振荡方法

通过测量导电介质交流阻抗特性参数可实现多种物理或化学量的检测.对一阶传感系统添加电容或电感元件以构成二阶谐振单元,用连续方波脉冲信号激励谐振单元进入自由衰减振荡模式,可同时获取谐振单元的衰减因子和谐振频率.对金属板材的电涡流检测及盐溶液的电导率测量系统分别进行了实验.结果表明,这种方法可有效抑制提离距离或电极引线等非理想因素,在交流阻抗测量技术的传感器化研究方面有很好的应用前景.

A Free Damped Oscillation Method for AC Electrical Impedance Measurement of Conductive Medium

Many physical or chemical parameters can be obtained by measuring the AC electrical impedance characteristics of conductive medium.By adding an inductor or capacitor to the one-order sensing system,a second-order resonant element can be constructed.When the element is excited by continuous square wave signals,it is forced into a free damped oscillation mode.The decay factor and resonant frequency can be simultaneously obtained.Experiments were done with an eddy current detection system for plate metals and a conductivity measurement system for saline solution,respectively.The results indicate that this method can suppress the non-ideal influences of lift off or the lead of electrodes.Potential application can be prospected in sensorization of AC electrical impedance measurement technology.