Ferroelectric Bi₂O₂Te‐Based Plasmonic Biosensor for Ultrasensitive Biomolecular Detection

Abstract Ultrasensitive detection of biomarkers, particularly proteins, and microRNA, is critical for disease early diagnosis. Although surface plasmon resonance biosensors offer label‐free, real‐time detection, it is challenging to detect biomolecules at low concentrations that only induce a minor mass or refractive index change on the analyte molecules. Here an ultrasensitive plasmonic biosensor strategy is reported by utilizing the ferroelectric properties of Bi₂O₂Te as a sensitive‐layer material. The polarization alteration of ferroelectric Bi₂O₂Te produces a significant plasmonic biosensing response, enabling the detection of charged biomolecules even at ultralow concentrations. An extraordinary ultralow detection limit of 1 fm is achieved for protein molecules and an unprecedented 0.1 fm for miRNA molecules, demonstrating exceptional specificity. The finding opens a promising avenue for the integration of 2D ferroelectric materials into plasmonic biosensors, with potential applications spanning a wide range.