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Comparative Analysis of Sub-6 GHz Microwave Sensors Suitable for Low-Cost In-Situ Microplastic Detection

2025 1 citation ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Maria do Carmo Vieira, Giovanna Monteiro Bianchi J. Santos, Antonio Augusto Lisboa de Souza, Carlos Alberto de Souza Filho, A.M.N. Lima

Summary

This engineering paper compares the performance of several microwave resonator sensor designs for detecting microplastics in water, motivated by the growing availability of low-cost handheld instruments. Laboratory tests showed meaningful differences in sensitivity between sensor geometries, with one design showing the highest relative frequency shift in response to a nylon sample. While purely technical, such sensor development work is an important step toward affordable, portable microplastic monitoring tools that could be deployed in rivers, tap water systems, or food processing facilities.

Polymers

Motivated by the recent availability of very low-cost portable vector network analyzers, we compare in this paper the performance of sub-6 GHz microwave sensors suitable for use in microplastics detection applications. To ensure a fair comparison, the selected sensors are implemented on the same RF substrate and submitted to the same boundary conditions. The impact of a nearby Nylon sample on their resonance frequency is analyzed through simulations as well as experimentally. Although the sensor with the highest natural resonance frequency is shown to exhibit the highest absolute frequency deviation among all sensors studied, another sensor exhibited the highest relative frequency deviation: it could in principle be scaled to work near the high end of the sub-6 GHz band to provide the highest sensitivity among all sensors.

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