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Microfluidic Microwave Sensor for Rapid Detection of Microplastics in Water: Optimization, Modeling, and Performance Evaluation

IEEE Sensors Journal 2024 8 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Haoxiang Wen, Yifan Zhao, Tingkai Shi, Mingxuan Li, Tao Li, Yiting Xu, Haiyang Jia, Wen Zhu, Longxiang Han, Longxiang Han, Sheng Yan, Jiawei Sun

Summary

Researchers developed a microfluidic sensor that uses microwave technology to rapidly detect microplastics in water samples without physical contact. The sensor was optimized to distinguish between different concentrations and sizes of plastic particles with high sensitivity. The technology could enable faster and more practical on-site monitoring of microplastic contamination in water supplies.

In recent years, microplastics (MPs) have become the focal point of an increasing number of studies due to their potentially detrimental effects on human health. Currently, the detection of MPs poses an exceedingly challenging task, particularly methods that enable rapid, on-site detection. Herein, we have developed a rapid and microfluidic-based microwave detection sensor. By optimizing the parameters of the electric inductive-capacitive resonator and microfluidic channel, a noncontact sensor with a high sensitivity is successfully fabricated. This sensor concentrates the electromagnetic field between the coupling regions at a central frequency of 4.7 GHz, maximizing the interaction between the sample and the electric field. The results demonstrate that the microwave sensor exhibits high sensitivity by detecting the S11 resonance frequency shift of ~10 MHz with a 1% change in MP concentration. Notably, the as-fabricated sensor exhibits ideal linearity in various MP detections, and their coefficients of determination (CODs) reach astonishing levels of ~0.999, reflecting the excellent performance of the sensor. Simultaneously, the Maxwell-Garnett (MG) model has been applied for the first time to electromagnetic analysis in MP/water systems, confirming its high suitability for low-concentration scenarios. Based on this, a mathematical model has been established to provide a reasonable explanation for the excellent linearity. The high-performance sensors and theoretical analysis provide a new approach for future MP sensor design and fabrication, paving the way for on-site and rapid MP detection.

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