Ultrasensitive Terahertz Biodetection Enabled by Quasi‐BIC‐Based Metasensors

Abstract

Advanced sensing devices, highly sensitive, and reliable in detecting ultralow concentrations of circulating biomarkers, are extremely desirable and hold great promise for early diagnostics and real‐time progression monitoring of diseases. Nowadays, the most commonly used clinical methods for diagnosing biomarkers suffer from complicated procedures and being time consumption. Here, a chip‐based portable ultra‐sensitive THz metasensor is reported by exploring quasi‐bound states in the continuum (quasi‐BICs) and demonstrate its capability for sensing low‐concentration analytes. The designed metasensor is made of the designed split‐ring resonator metasurface which supports magnetic dipole quasi‐BIC combining functionalized gold nanoparticles (AuNPs) conjugated with the specific antibody. Attributed to the strong near‐field enhancement near the surface of the microstructure enabled by the quasi‐BICs, light‐analyte interactions are greatly enhanced, and thus the device's sensitivity is boosted significantly. The system sensitivity slope is up to 674 GHz/RIU, allowing for repeatable resolving detecting ultralow concentration of C‐reactive protein (CRP) and Serum Amyloid A (SAA), respectively, down to 1 pM. The results touch a range that cannot be achieved by ordinary immunological assays alone, offering a novel non‐destructive and rapid trace measured approach for next‐generation biomedical quantitative detection systems.

Improving Sensitivity and Reproducibility of Surface-Enhanced Raman Scattering Biochips Utilizing Magnetoplasmonic Nanoparticles and Statistical Methods

“…For another SERS-based assay that does not employ magnetoplasmonic particles, a biosensor was constructed comprising DNA three-way junction-conjugated porous Au NPs and an Au–Te nanoworm structure, achieving an LOD of 0.51 ng/mL for CRP in PBS . The ultrasensitive THz metasensor, based on quasi-bound states in the continuum (quasi-BICs), exhibits exceptional sensitivity, detecting biomarkers like CRP and serum amyloid A down to 1 pM (0.12 ng/mL) . On the other hand, the electrochemical immunosensor, using indole as an electrochemical probe, demonstrates an LOD of 0.03 ng/mL .…”

“…49 The ultrasensitive THz metasensor, based on quasi-bound states in the continuum (quasi-BICs), exhibits exceptional sensitivity, detecting biomarkers like CRP and serum amyloid A down to 1 pM (0.12 ng/mL). 50 On the other hand, the electrochemical immunosensor, using indole as an electrochemical probe, demonstrates an LOD of 0.03 ng/mL. 51 The real-time nanoplasmonic immunoturbidimetry assay (NanoPITA) quantifies hypersensitive CRP with a reduced LOD of 0.54 ng/ mL.…”

Coupling-Based Multiple Bound States in the Continuum and Grating-Assisted Permittivity Retrieval in the Terahertz Metasurface

“…In the terahertz (THz) regime, the engineering of a high-quality ( Q -value) resonance in the metasurfaces is one of the avenues for the giant localized electromagnetic field enhancement, − which is desirable for the development of the trace amount biochemical sensing − and on-chip THz strong-field platform . In the past few years, a wave of research on metasurfaces supporting bound states in the continuum (BICs) has been sparked for their ability to customize high- Q resonances in a flexible manner, − which can be exploited for broad applications associated with ultrasensitive sensing, , nonlinear optical platform, − chirality, and diffraction control .…”

Vibrational Alchemy of DNA: Exploring the Mysteries of Hybridization under Cooperative Strong Coupling with Water

“…In recent years, vibrational strong coupling (VSC) has attracted extensive attention from scientific fields, e.g., photonics, chemistry, materials, and biomedicine. VSC occurs as the vibrational modes of a substance can interact with photonic modes in a resonant manner, resulting in a coherent exchange of energy. , These substances include both small molecules (e.g., water, hormones, and heme) and macromolecules (e.g., deoxyribonucleic acid (DNA), proteins, and enzymes). − Generally, molecules are placed in between two parallel reflecting mirrors, so-called optical resonators, e.g., the Fabry–Pérot (FP) resonator. , The VSC status can be realized by simply adjusting the distance between the two mirrors, termed the light path or cavity distance, as its photonic energy level is equal to the vibrational frequency of the molecules in it. Several research teams have applied the VSC effect to a variety of reaction systems .…”