The Sensitivity of Grating-Based SPR Sensors with Wavelength Interrogation.

Jianjun Cao,Yuan Sun,Yan Kong,Weiying Qian

doi:10.3390/s19020405

Abstract

In this paper, we derive the analytical expression for the sensitivity of grating-based surface plasmon resonance (SPR) sensors working in wavelength interrogation. The theoretical analysis shows that the sensitivity increases with increasing wavelength and is saturated beyond a certain wavelength for Au and Ag gratings, while it is almost constant for Al gratings in the wavelength range of 500 to 1000 nm. More importantly, the grating period (P) and the diffraction order (m) dominate the value of sensitivity. Higher sensitivity is possible for SPR sensors with a larger grating period and lower diffraction order. At long wavelengths, a simple expression of P/|m| can be used to estimate the sensor sensitivity. Moreover, we perform experimental measurements of the sensitivity of an SPR sensor based on an Al grating to confirm the theoretical calculations.

Highlights

Biosensors based on surface plasmon resonance (SPR) have received much attention since their first application in gas sensing in 1983 [1]
We have derived analytical expressions for the sensitivity of SPR sensors based on metalIngratings withwe wavelength interrogation
Thethe theoretical analysis, sensitivity conclusion, have derived analytical According expressionstofor sensitivity of SPR the sensors based increases with increasing wavelength and is saturated beyond a certain wavelength for

Summary

Introduction

Biosensors based on surface plasmon resonance (SPR) have received much attention since their first application in gas sensing in 1983 [1]. Sensors 2019, 19, 405 et al find that S approaches λ/n at long wavelengths, where λ is the wavelength and n is the refractive index of the analyte [30]. In their theoretical derivation the incident angle in the the analyte. The angle in the analyte varies with its refractive index according refractive index according to Snell’s to Snell’s law.paper, we derive the theoretical expression for the sensitivity of grating-based SPR. In wewavelength derive the theoretical expression for the sensitivity of grating-based sensors sensors working interrogation.

Theoretical

Schematic

Experimental Demonstration

Conclusions