Radical Shielding Suppresses False Positives in Self-Powered Microfluidic Sensors

Fuel cell-driven self-powered sensors facilitate continuous environmental analysis, but they frequently suffer from false-positive signals caused by coexisting interfering species. Herein, a radical shielding strategy was developed by integrating peroxymonosulfate (PMS) fuel into the self-powered sensors. With photoactivation of the PMS fuel, sulfate and hydroxyl radicals (SO4•- and •OH) generated on the cobalt-based photoelectrodes promoted the transformation of interfering species and reduced nonspecific signals caused by these species. The oxidative radicals were simultaneously coupled with the molecularly imprinted polymer (MIP) assembled on the sensor. Through this synergistic design, the sensor reduced interference signals at the sensing interface while preserving the selective binding of levofloxacin (LEV) to the MIP sites, leading to accurate signal responses. In anti-interference assessments, the radical shield provided the sensor with superior resistance compared to the unshielded state. The sensor reduced false-positive signal fluctuations from over 600% to below 5%, even in the presence of 12 coexisting interferents at 10-fold higher concentrations. As a proof of concept, the radical strategy was integrated into a microfluidic sensing chip to detect LEV in river water, achieving reliable recovery rates ranging from 97.68 to 104.20%. This work improves resistance to interference and enhances selectivity for self-powered sensors, ensuring accurate and robust on-site monitoring capabilities in complex environments.