Electro-Microfluidic Sensor for Quantitative Detection of Microplastics in Saline Freshwater

This thesis investigates a DC microfluidic sensor incorporating a Wheatstone bridge and MXene-coated microwires to detect and quantify microplastics in freshwater with varied salinity. The study addresses the limitations of traditional detection methods, particularly in higher freshwater salinity where microplastics exhibit reduced electrophoretic mobility. The sensor's performance was evaluated across a range of microplastic concentrations (1–25 ppm) suspended in saline solution with varying NaCl concentrations (0–1000 ppm) to assess sensitivity and detection limits. Results demonstrated a significant reduction in electrical resistance as microplastics accumulated at the anode, indicating successful detection at lower salinities. However, at higher salt concentrations, microplastic accumulation and sensor sensitivity declined. Modifications, including constant current application and MXene functionalization, enhanced accumulation rates, and detection performance. Future research is required to investigate diverse microplastic types, shapes, and biological interferences to improve real-world applicability. This work provides a foundation for low-cost, sensitive microplastic detection in aquatic environments.