Topological Darkness: How to Design a Metamaterial for Optical Biosensing with Virtually Unlimited Sensitivity

TL;DR

This paper introduces a topologically dark metamaterial design that achieves near-unlimited sensitivity for optical biosensing, overcoming fundamental loss-related limitations of existing biosensors.

Contribution

The authors propose a novel topological design principle called the scissor effect, enabling ultra-sensitive biosensing with practical fabrication strategies.

Findings

Demonstrated detection of folic acid with 0.125 nM limit of detection

Achieved a 3-log linear dynamic range in biosensing

Surpassed sensitivity of all previous optical biosensors

Abstract

Due to the absence of labels and fast analyses, optical biosensors promise major advances in biomedical diagnostics, security, environmental and food safety applications. However, sensitivity of the most advanced plasmonic biosensor implementations has a fundamental limitation caused by losses in the system and or geometry of biochips. Here, we report a scissor effect in topologically dark metamaterials which is capable of providing virtually unlimited bona fide sensitivity to biosensing thus solving the bottleneck sensitivity limitation problem. We explain how the scissor effect can be realized via a proper design of topologically dark metamaterials and describe strategies for their fabrication. To validate the applicability of this effect in biosensing, we demonstrate the detection of folic acid (vitamin important for human health) in the wide 3-log linear dynamic range with the limit of detection of 0.125 nM, which is orders of magnitude better than previously reported for all optical counterparts. Our work opens possibilities for designing and realising plasmonic, semiconductor and dielectric metamaterials with ultra-sensitivity to binding events.