Insulin detection using plasmonic optical fiber chips: a benchmark

Abstract

Plasmonic optical fiber-based biosensors are currently in their early stage of development as practical and integrated devices, gradually making their way towards the biosensing market. While the majority of these plasmonic biosensors operate using white light sources and glass prisms or multimode optical fibers (OFs), our approach centers on single-mode OFs coupled with tilted fiber Bragg gratings (TFBGs) in the near-infrared wavelength range. Our objective is to enhance surface sensitivity and broaden sensing capabilities of OF-based sensors to develop in situ sensing with remote interrogation. In this study, we comprehensively assess their performance in comparison to the gold-standard plasmonic reference, a commercial device based on the Kretschmann-Raether prism configuration, namely the Biacore X100. We present their respective refractive index sensitivity and their efficiency for insulin detection using a dedicated microfluidics approach. By optimizing a consistent surface biotrapping methodology, we elucidate the dynamic facets of both technologies and highlight their remarkable sensitivity to variations in both bulk and surface properties. The one-toone comparison between both technologies demonstrates the reliability of optical fiber-based measurements, showcasing similar experimental trends obtained with both the prismatic configuration and gold-coated TFBGs, with an even enhanced limit of detection for the latter. This study lays the foundation for the detection of punctual molecular interactions and opens the way towards the detection of spatially and temporally localized events on the surface of optical probes, paving the way for their implementation in field conditions.