Label-Free Bound-States-in-the-Continuum Biosensors

Abstract

Bound states in the continuum (BICs) have attracted considerable attentions for biological and chemical sensing due to their infinite quality (Q)-factors in theory. Such high-Q devices with enhanced light-matter interaction ability are very sensitive to the local refractive index changes, opening a new horizon for advanced biosensing. In this review, we focus on the latest developments of label-free optical biosensors governed by BICs. These BICs biosensors are summarized from the perspective of constituent materials (i.e., dielectric, metal, and hybrid) and structures (i.e., grating, metasurfaces, and photonic crystals). Finally, the current challenges are discussed and an outlook is also presented for BICs inspired biosensors.

High-Sensitivity Optical Sensors Empowered by Quasi-Bound States in the Continuum in a Hybrid Metal–Dielectric Metasurface

“…Recently, bound states in the continuum (BICs) provide opportunities for the design of high- Q optical devices. − A BIC in periodic nanostructures is a nonradiative dark mode in the continuum coexisting with radiation waves. Theoretically, BICs can effectively suppress radiation loss and have infinite Q factors.…”

Bound States in the Continuum and Induced Resonances in a Simple Plasmonic Waveguide with Sensing Application

“…Our MIM plasmonic structure can also be used as a biosensor to measure the concentration of unknown samples from human blood [15,49,50]. In this section, we use our cavity to measure certain electrolytes in human blood samples, including Na + , K + , and glucose.…”

“…Also, it is established that the sensitivity of MIM waveguides is higher than multilayers [13]. These plasmonic devices incorporate filters [14], sensors [15], demultiplexers [16], Mach-Zehnder interferometer (MZI) [17], and applications in highly integrated optical circuits [18]. Experimentally, MIM plasmonic waveguides have been implemented to observe plasmon-induced transparency (PIT) [19] and Fano resonances [20] in the visible and infrared domain using silver (Ag) or gold (Au) as the metal layer [21][22][23].…”

“…Recently, there has been a surge of interest in bound states in the continuum (BICs) [15,24] that have revolutionized nanostructures by providing the way to high-throughput optical sensing devices with enhanced light-matter interaction at the nanoscale [25][26][27][28][29][30][31]. BICs [32] are special types of resonant modes with an infinite lifetime that are still confined in certain parts of the system even though their frequencies lie in the radiative area.…”

Pushing Optical Virus Detection to a Single Particle through a High-Q Quasi-bound State in the Continuum in an All-dielectric Metasurface

“…With regards to traditional electrochemical biosensing technologies, tedious preparation and setups are often demanded. For example, when it comes to the observational analysis of virus, the transmission electron microscope (TEM) has traditionally been the first choice. , Nevertheless, the high cost on time and material, and sophisticated sample preparation required for imaging analysis have been the obstacles for its utility in basic cases. , Oppositely, by means of an in situ and slightly invasive technique, optical biosensing can overcome the drawbacks of being invasive, time-consuming, and expensive. − Besides, it is advantageous under specific harsh circumstances with complex environments, such as intense electric fields and waves or extreme temperatures, because it exhibits a relatively robust and nonconductive sensor element. , Therefore, they can function without insulation problems, explosion hazards, or being excessively influenced by certain disturbances in the surroundings.…”