Design of an electrically driven membrane-based microfluidic coupled sensing chip based on cation-exchange membrane and its application in trace heavy metal ion detection

In this study, an electrically driven membrane and microfluidic coupled chip is proposed to drive heavy metal ions through an ion exchange membrane by an electric field, thereby separating them from organic matter in water. The ions were regulated by adjusting the voltage, solution environment, and detection conditions, which enabled the preferential detection of lead and cadmium ions, thus reducing the interference of other cations. The ion exchange membrane prevents dissolved organic matter from coming into contact with the electrode, thus reducing the influence of organic matter on the measurement results by approximately 10%. After comparing the membrane materials that are more suitable for the application of the system, they are further modified, and the final detection time is shortened by about 50s compared with the original. Improved screen-printed electrodes further enhance the performance of the on-chip electrochemical sensors, and the coupled chip allows for simultaneous pre-processing and ion detection and provides a stable environment for the detection. The coupled electrochemical detection platform exhibited good linear response for Cd2+ and Pb2+ with detection limits of 0.21 and 0.46 ug/L (S/N=3).