Entangled Nanoplasmonic Cavities for Estimating Thickness of Surface-Adsorbed Layers

Abstract

Plasmonic sensors provide real-time and label-free detection of biotargets with unprecedented sensitivity and detection limit. However, they usually lack the ability to estimate the thickness of the target layer formed on top of the sensing surface. Here, we report a sensing modality based on reflection spectroscopy of a nanoplasmonic Fabry–Perot cavity array, which exhibits characteristics of both surface plasmon polaritons and localized plasmon resonances and outperforms its conventional counterparts by providing the thickness of the surface-adsorbed layers. Through numerical simulations, we demonstrate that the designed plasmonic surface resembles two entangled Fabry–Perot cavities excited from both ends. Performance of the device is evaluated by studying sensor response in the refractive index (RI) measurement of aqueous glycerol solutions and during formation of a surface-adsorbed layer consisting of protein (i.e., NeutrAvidin) molecules. By tracking the resonance wavelengths of the two modes of the nanoplasmonic surface, it is therefore possible to measure the thickness of a homogeneous adsorbed layer and RI of the background solution with precisions better than 4 nm and 0.0001 RI units. Using numerical simulations, we show that the thickness estimation algorithm can be extended for layers consisting of nanometric analytes adsorbed on an antibody-coated sensor surface. Furthermore, performance of the device has been evaluated to detect exosomes. By providing a thickness estimation for adsorbed layers and differentiating binding events from background RI variations, this device can potentially supersede conventional plasmonic sensors.

Surface plasmon resonance biosensor with laser heterodyne feedback for highly-sensitive and rapid detection of COVID-19 spike antigen

“…The sensitivity is calculated to be 1.07 × 10 6 mV/RIU and the noise-limited resolution is calculated to be 3.75 × 10 −8 RIU, which is better than most reported results. ( Giorgini et al, 2013 ; Li et al, 2020 ; Mataji-Kojouri et al, 2020 ; Park and Park, 2021 ; Wu et al, 2021 ; Zhu et al, 2021 ), showing that this biosensor is capable of detecting the viral antigen.…”

Time-Resolved Thickness and Shape-Change Quantification using a Dual-Band Nanoplasmonic Ruler with Sub-Nanometer Resolution

“…The triple sensitivity at a layer thickness up to ∼20 nm compared to those beyond ∼50 nm stems from the characteristic high local sensitivity of LSPR sensors, which is a consequence of the rapidly decaying near elds. The overall sensitivity of our dual-mode LSPR nanoruler in the few tens of nanometer thickness range is therefore at least twice as high as for LSPR-SPR mode 31 and dual SPR mode 33 solutions. Assessing the noise, it is clear that it is constant throughout the experiment and is small, i.e., σ r = 0.004 and σ t = 0.13 nm for the Δλ peak ratio and thickness determination, respectively.…”

Carbon‐Based Nanomaterials and Sensing Tools for Wearable Health Monitoring Devices

“…[138,139] For optoelectronic and electrochemical applications, dielectrics also have been used to design light-emitting diodes, [140] solar cells, [141] photonic crystals, [142] waveguides, [143] supercapacitors, [144] transistors, [145] piezoresistors, [146] and surface plasmon resonance-based biosensors. [147][148][149][150][151][152] Among various counterparts, polymer-based dielectrics have been in demand owing to their design flexibility, dielectric strength, low cost, reproducibility, and good processability. [153][154][155] Moreover, dielectric loss/constant behaviors of materials, the breakdown voltage, and the real part of the permittivity limit or enhance their energy storage capacity.…”