Biosensing using topologically dark metamaterials

Being associated with exactly zero light reflection/transmission from a dedicated optical system, the phenomenon of Topological Darkness (TD) can provide unique properties to radically advance the sensitivity of label-free biosensing. Here, we highlight some recent advances in the development of topologically dark metamaterials, which make possible virtually unlimited sensitivity in spectral and phase interrogations. First, we present 3D metamaterials, which provide zero intensity in reflection and thus make possible the generation of singularities of light phase in the minima of light reflection. In turn, such a singularity is capable of providing ultrahigh sensitivity if phase is used as the interrogation parameter. Then, we describe how to create metamaterials focusing on the spectral response of the TD feature to refractive index variations in the amplitude interrogation channel. We show that properly designed topologically dark metamaterials can also provide a “scissor effect”, which leads to ultrahigh spectral sensitivity in the recording of binding biosensing events using the standard intensity measurements. These works open up opportunities for designing and implementing plasmonic and other metamaterials providing biosensor sensitivity beyond the state-of-the-art.