平面叉指电极溶液阻抗的低频三角波测量

Measurement of planar-interdigitated electrolyte impedance by triangular waveform voltage at low frequencies

针对低浓度电解质溶液中生物细胞阻抗微弱变化过程的测量问题,研究了一种三角波电压激励结合主元分析(PCA)的测量方法。用三角波电压信号作为激励,采集单周期响应电流信号构成测量向量,由不同时刻所得测量向量组成测量矩阵,PCA处理后的载荷向量中即包含有溶液阻抗的变化信息。这种信号处理方式对阻抗变化过程的测量结果不依赖于等效阻抗模型的计算,同时可有效避免等效阻抗计算过程中的噪声问题。对低浓度氯化钾溶液中硅基底金电极、PCB基底铜电极和PCB基底镀金电极3种平面叉指电极进行了实验分析。实验结果表明,三角波激励结合PCA处理的方法可实现对溶液电导率微弱变化过程的有效检测。

In order to measure the minor impedance changing process of biological cell suspensions in low concentrated electrolyte solutions,a method of triangular waveform voltage excitation is investigated together with principal component analysis（ PCA）. Using the triangular waveform voltage as the excitation signal,the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by measured vectors obtained at different measurements. After processed by PCA,the changing information of the solution impedance is contained in the loading vectors. Measurement results of impedance changing with the proposed signal processing method are independent on the equivalent circuit model. The noise- induced problems encountered during the equivalent impedance calculation are therefore avoided. Three kinds of planar- interdigitated electrodes,i. e. Au electrode on Si substrate,Cu electrode on PCB substrate and Au electrode on PCB substrate,are experimentally tested in low concentrated KCl solutions.Experimental results indicate that minor solution conductivity changes can be effectively measured with the proposed method of triangular waveform voltage excitation combined with PCA.