Nanoscale Plasmonic Interferometers for Multispectral, High-Throughput Biochemical Sensing

In this work, we report the design, fabrication, and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form two-arm, three-beam, planar plasmonic interferometers. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400–800 nm). A wavelength sensitivity between 370 and 630 nm/RIU (RIU, refractive index units), a relative intensity change between ∼10³ and 10⁶ %/RIU, and a resolution of ∼3 × 10^–7 in refractive index change were experimentally measured using typical sensing volumes as low as 20 fL. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time, and extremely compact biochemical sensors