Probe-Type Fiber Optic Biosensor Based on Barium Titanate Glass Microsphere Enhanced SPR Effect for Virus RNA Detection

In this paper, a groundbreaking probe-type fiber optic biosensor, harnessing the surface plasmon resonance (SPR) effect enhanced by barium titanate glass microspheres, is unveiled for virus RNA detection. The multi-physics simulation was used to verify the sensitivity improvement achieved by introducing barium titanate microspheres on the surface of the optical fiber microspheres probe. Experiments confirmed this, pushing the sensor's limit to an impressive 6802 nm/RIU. Biomarker capture on the microsphere surface subtly alters the local refractive index, triggering a detectable SPR spectral shift. To showcase its prowess, the sensor tackled the reverse-transcribed complementary DNA (cDNA) of COVID-19 RNA. Chemical modification of the gold film and DNA hybridization technology ensured specific cDNA detection. The limit of detection for this target reached a remarkable 1.58 nmol/L. This sensor not only excels in virus RNA detection but also holds immense potential for diagnosing major diseases by pinpointing the concentrations of key biomarkers.