One-Dimensional High-Q Silicon Nanoparticle Chain Resonators for Refractive Index Sensing

Label-free optical biosensors using nanophotonic concepts have made substantial progress in the past few years because of their ability to realize fast, compact, and cost-effective chemical detection devices. Among those, high-refractive-index dielectric Mie nanoresonators hold promise for deep miniaturization of biosensing devices while maintaining high sensitivity and low dissipative losses. In this work, we report a high-sensitivity and small-footprint refractive index sensor based on this concept. The device consists of a one-dimensional chain of coupled silicon nanoresonators supporting high-quality-factor collective Mie modes. Measurements with aqueous glycerol solutions show a high sensitivity range of 420-440 nm/refractive index unit (RIU) and a maximum figure of merit of 2700 RIU-1. Being fully compatible with standard complementary metal-oxide semiconductor processes and having a small sensing area of only 0.5 x 18.2 mu m(2), this design, once arranged in arrays functionalized for different analytes, we believe could become an attractive solution to realizing lab-on-a-chip sensor arrays for high-performance, label-free multiplexing in a cost-effective way.