Scaling Nanophotonic Interferometric Biosensors toward Parallel Detection of Multiple Biomarkers

Silicon photonics has emerged as a promising technology for next-generation biosensors. Its CMOS compatibility, miniaturization, and large-scale fabrication capabilities, combined with high sensitivity, fast response, and inherent label-free detection capabilities, have positioned this technology at the forefront for the deployment of point-of-care (PoC) analytical platforms. However, operating a multiplexed photonic biosensor configuration remains challenging due to limitations such as efficient light coupling to multiple sensing elements, simultaneous signal acquisition, precise microfluidics and biofunctionalization, and optical crosstalk management between sensors. In this study, we introduce an interferometric biosensor that incorporates a new multiplexed nanophotonic bimodal waveguide (BiMW) chip with a compatible microfluidic system and an optimized light-coupling and readout configuration that enables simultaneous, individual detection of up to seven targets in the same sample. All system components have been incorporated into a compact prototype providing an outstanding bulk limit of detection (LOD) of (7 ± 5) × 10-7 RIU. The biosensor capabilities have been validated against a representative clinical scenario, demonstrating effective and sensitive detection of Respiratory Syncytial Virus (RSV) nucleoproteins relevant to infectious disease diagnostics, achieving a simultaneous LOD of 1.2 ± 0.4 ng·mL-1 across all seven sensors.