Development of microfluidic device to monitor the contamination in drinking water using impedance spectroscopy

Microplastic contamination is a growing concern, as microplastics have been found in brain tissue and can enter the body through consumption. The objective of this research is to develop a microfluidic device to monitor microplastic particles by using electrical impedance spectroscopy principles. The device operates based on a flow-through principle. The configuration of electrode consists of copper-based cylindrical electrode with diameter of 300 micrometer and a center-to-center spacing of 2000 micrometer. The electrodes are designed to be replaceable. The microchannel has a rectangular cross-section with a width of 2000 micrometer and a height of 1000 micrometer. The microfluidic device was fabricated using a stereolithography approach with BioMed Clear resin. Experiments were conducted at a flow rate of 1 mL/min, with an AC excitation frequency ranging from 20 Hz to 10 MHz. The particle-sensing performance was evaluated by using polystyrene beads with diameters of 30, 15, 10 and 5 micrometer dispersed in drinking water. The experimental results show that as the concentration of microplastics increases the magnitude of the minimum reactance at the critical frequency in the semicircle of Nyquist plot also increases. However, when acidic and alkaline interferences were introduced for 15-µm polystyrene beads in drinking water at pH 6 and 8, the microplastic signals were disturbed, reducing the efficiency of microplastic detection. Ultimately, this microfluidic device design represents a practical step toward household-level and field monitoring. Furthermore, this research aims to raise awareness of the growing issue of microplastic contamination in the environment and its negative impact on human health.