Anti-interference, self-cleaning plasmonic sensor integrating COF molecular sieve and multifunctional Ag nanoparticles

Tilted fiber Bragg grating-based surface plasmon resonance (TFBG-SPR) sensors, despite their portability and high sensitivity, often suffer from background interference and lack self-cleaning capabilities. Although two-dimensional materials possess the capacity to enhance sensor functionality, their integration frequently results in uneven dispersion or agglomeration of nanosheets, compromising stability and reproducibility. Herein, a novel TFBG-SPR sensor that integrates a large-area, self-supported covalent organic framework (COF) film with Ag nanoparticles (NPs) is proposed. The COF-366 film functions as a molecular sieve, selectively isolating target analytes from background molecules, thereby improving anti-interference performance. The Ag NPs generate localized surface plasmon resonance (SPR) hotspots, significantly enhancing the signal of the target analyte. Moreover, the sensor exhibits robust self-cleaning properties through SPR-driven photocatalytic degradation. These attributes collectively endow the sensor with superior anti-interference, self-cleaning, and high-sensitivity functionalities, making it suitable for reliable detection in practical applications. Experimental validation reveals that the sensor effectively eliminates background interference and maintains consistency across repeated measurements, achieving a detection limit of 1.5 × 10 –10 M for methylene blue. This work offers a promising candidate for large-scale environmental monitoring and other challenging detection scenarios, thereby expanding the application range of COF materials in advanced photonic devices.