Toroidal Plasmonic Meta-Biosensors: Benchmarking against Classical Plasmonic Biosensors and Transducers

Rapid progress in plasmonics biosensors and immunosensors brings many methodologies to employ resonant subwavelength structures associated with the physics of multipoles, Fano resonances, and analogous moments. Here, we review a broad range of traditional and novel techniques that have been utilized for developing advanced biosensing tools including colloidal nanoparticles (NPs)-based systems to well-engineered arrays of meta-atoms and metamolecules. By describing some of the important and practical label-free biosensing methods based on subwavelength plasmonic technology, we discuss the emerging and excitation of toroidal multipoles concept, as a third family of multipolar modes, has made a revolution in enhancing the sensing performance of ultra-low weight diseases proteins and viruses as biological targets. Taking the exquisite and untraditional advantages of toroidal plasmonic metasurfaces, we comprehensively evaluated the detection properties and high-quality of toroidal immunosensors for the sensing of signature of bioproteins at picomolar (pM) concentrations with excellent limit of detection (LOD). This understanding clearly shows how toroidal metasensors have emerged as promising clinical and pharmacology tools, can be considered as alternatives and big competitors for conventional plasmonic sensors and transducers.