State Key Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Sensors (Basel). 2021 Sep 24;21(19):6381. doi: 10.3390/s21196381.
In this work, a new capacitively coupled contactless conductivity detection (CD) sensor for microfluidic devices is developed. By introducing an LC circuit, the working frequency of the new CD sensor can be lowered by the adjustments of the inductor and the capacitance of the LC circuit. The limits of detection (LODs) of the new CD sensor for conductivity/ion concentration measurement can be improved. Conductivity measurement experiments with KCl solutions were carried out in microfluidic devices (500 µm × 50 µm). The experimental results indicate that the developed CD sensor can realize the conductivity measurement with low working frequency (less than 50 kHz). The LOD of the CD sensor for conductivity measurement is estimated to be 2.2 µS/cm. Furthermore, to show the effectiveness of the new CD sensor for the concentration measurement of other ions (solutions), SO and Li ion concentration measurement experiments were also carried out at a working frequency of 29.70 kHz. The experimental results show that at low concentrations, the input-output characteristics of the CD sensor for SO and Li ion concentration measurement show good linearity with the LODs estimated to be 8.2 µM and 19.0 µM, respectively.
在这项工作中，开发了一种用于微流控器件的新型电容耦合非接触式电导检测（CD）传感器。通过引入 LC 电路，可以通过调整电感和 LC 电路的电容来降低新 CD 传感器的工作频率。新 CD 传感器的检测限（LOD）可用于电导率/离子浓度测量得到改善。在微流控器件（500 µm × 50 µm）中进行了 KCl 溶液的电导率测量实验。实验结果表明，所开发的 CD 传感器可以实现低工作频率（低于 50 kHz）的电导率测量。CD 传感器的电导率测量 LOD 估计为 2.2 µS/cm。此外，为了展示新 CD 传感器对其他离子（溶液）浓度测量的有效性，还在 29.70 kHz 的工作频率下进行了 SO 和 Li 离子浓度测量实验。实验结果表明，在低浓度下，CD 传感器的 SO 和 Li 离子浓度测量的输入-输出特性具有良好的线性度，其 LOD 估计分别为 8.2 µM 和 19.0 µM。
