We report a silicon-nitride slot-waveguide microring resonator functionalized with monoclonal antibodies against the respiratory-syncytial-virus (RSV) fusion (F) protein for label-free, real-time detection of RSV. The 100 μm-radius slotted ring exhibits a loaded quality factor of 3.5 × 104 and a bulk sensitivity of 275 nm/RIU at 1310 nm. Langmuir fitting of recombinant F-protein titrations (0.05–3 nM) gives an equilibrium dissociation constant KD = 5.4 × 10-2 nM and Δλmax = 7.3 nm (R² = 0.997)…
