Enhancement of Sensitivity with High-Reflective-Index Guided-Wave Nanomaterials for a Long-Range Surface Plasmon Resonance Sensor.

Leiming Wu,Kai Che,Yuwen Qin,Yuanjiang Xiang

doi:10.3390/nano12010168

Abstract

A guided−wave long−range surface plasmon resonance (GW−LRSPR) sensor was proposed in this investigation. In the proposed sensor, high−refractive−index (RI) dielectric films (i.e., CH3NH3PbBr3 perovskite, silicon) served as the guided−wave (GW) layer, which was combined with the long−range surface plasmon resonance (LRSPR) structure to form the GW−LRSPR sensing structure. The theoretical results based on the transfer matrix method (TMM) demonstrated that the LRSPR signal was enhanced by the additional high#x2212;RI GW layer, which was called the GW−LRSPR signal. The achieved GW−LRSPR signal had a strong ability to perceive the analyte. By optimizing the low− and high−RI dielectrics in the GW−LRSPR sensing structure, we obtained the highest sensitivity (S) of 1340.4 RIU−1 based on a CH3NH3PbBr3 GW layer, and the corresponding figure of merit (FOM) was 8.16 × 104 RIU−1 deg−1. Compared with the conventional LRSPR sensor (S = 688.9 RIU−1), the sensitivity of this new type of sensor was improved by nearly 94%.

Highlights

Are shown in Figure 1c, which indicates that an additional high−RI GW layer (CH3 NH3 PbBr3 perovskite) could improve the quality of the resonance signal
The result showed that the GW−long−range surface plasmon resonance (LRSPR) sensor had a higher sensitivity than that of the LRSPR sensor due to the enhancement of the resonance signal by the GW layer
The FWHM of the resonance signal became narrower after adding the GW layer, which promoted the improvement of the figure of merit (FOM) according to Equation (9)

Summary

Introduction

The Kretschmann–Raether (KR) configuration [1] is an important carrier for the excitation of the surface plasmon resonance (SPR) phenomenon [2,3,4]. Metals, such as gold (Au), silver (Ag), aluminum (Al), and copper (Cu), contain a large number of free electrons on their surface. These free electrons oscillate up and down in the direction perpendicular to the surface of the metal film under the excitation of TM−polarized light, thereby forming a surface plasmon wave (SPW). The SPR sensors are widely applied in environmental monitoring [5,6], biochemical reactions [7,8], medical diagnosis [9,10], and other fields

Methods

Results

Conclusion