Ultrathin plasmonic nanogratings for rapid and highly-sensitive detection

TL;DR

This paper presents a novel ultrathin nanoplasmonic sensor platform using one-dimensional nanogratings on 30nm-thick silver films, achieving rapid, highly-sensitive detection with high spatial and temporal resolution in a compact form.

Contribution

Introduction of a nanoplasmonic sensor with ultrathin silver nanogratings that enhances sensitivity and resolution while simplifying the detection geometry.

Findings

Refractive index resolution of 1.46x10^-6 RIU

Temporal resolution of 1 second

Sensor footprint of 50x50 micrometers

Abstract

We developed a nanoplasmonic sensor platform employing the extraordinary optical properties of one-dimensional nanogratings patterned on 30nm-thick ultrathin Ag films. Excitation of Fano resonances in the ultrathin Ag nanogratings results in transmission spectra with high amplitude, large contrast, and narrow bandwidth, making them well-suited for rapid and highly-sensitive sensing applications. The ultrathin nanoplasmonic sensor chip was integrated with a polydimethylsiloxane (PDMS) microfluidic channel, and the measured refractive index resolution was found to be 1.46x10-6 refractive index units (RIU) with a high temporal resolution of 1 sec. This compares favorably with commercial prism-based surface plasmon resonance sensors, but is achieved using a more convenient collinear transmission geometry and a significantly smaller sensor footprint of 50x50um2. In addition, an order-of-magnitude improvement in the temporal and spatial resolutions was achieved relative to state-of-the-art nanoplasmonic sensors, for comparable detection resolutions.