A Fully Integrated Portable Microplastic Detection System-on-Chip With High-Sensitivity RF MEMS Sensors and Narrow-Band Notch-Tracking Dielectric Discrimination Algorithms

초록

This article presents a fully integrated portable microplastic (MP) detection system-on-chip (SoC) that combineshigh-sensitivity radio frequency (RF) micro-electromechanicalsystem (MEMS) sensors with narrow-band notch-tracking algo-rithms for dielectric discrimination. Conventional MP detectionsystems suffer from the low transmit power (P-TX), restricted receiver dynamic range (DR), and the need for separate two-chip configurations, increasing complexity and cost. To overcomethese challenges, the proposed 180-nm CMOS MP detection SoCmonolithically integrates the sensor driver and readout func-tionalities, eliminating the need for multiple chips and reducingpower consumption. The MP detection SoC, originally developed for a 1.2-GHz notch RF MEMS sensor, was also evaluated with a2.84-GHz sensor, demonstrating its scalability for high-frequency MP detection. The system tracks the resonance points of the RFMEMS sensor to monitor transmission coefficient (S-21) variations,enabling quantitative analysis of MPs such as polyethylene (PE),polypropylene (PP), PE terephthalate (PET), polystyrene (PS),and polymethyl methacrylate (PMMA). By correlating notchfrequency shifts with variations in relative permittivity (epsilon r)and loss tangent [tan(delta)], it performs stepwise MP detectionand enables quantitative analysis of MPs. The system wasvalidated using real-world MPs, including 3-D polylactic acids(PLAs), aged water pipelines, and laundry wastewater, showing results consistent with thermogravimetric analysis-Fouriertransform-infrared (TGA-FT-IR) spectroscopy, with error rates ranging from 10% to 23%. These results highlight a compact, portable, and reliable solution for on-site MP detection underrealistic environmental conditions.

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