Exploiting Several Buffer Layers in SPR D-Shaped POF Sensors Based on Gold Film for Different Applications

Nunzio Cennamo,Francesco Arcadio,Luigi Zeni,Paola Zuppella

doi:10.3390/proceedings2019015047

Abstract

We present a comparative study of three optical sensing platforms based on surface plasmon resonance (SPR) in plastic optical fibers (POFs). The proposed sensors consist of a D–shaped POF sensing area, where the exposed core is covered by a photoresist layer, used as intermediate layer between the fiber’s core and the metal (gold) film. The photoresist deposited on the exposed core in the D–shaped POF region, is pivotal in order to improve the performances of the sensor in terms of sensitivity. In particular, we have compared the performances of three different buffer layers based on the following photoresist: Microposit SU-8 3005, Microposit S1813 before and after the expiry date.

Highlights

Surface plasmon resonance bio–chemical sensors in optical fibers are suitable for on-site and real-time monitoring of different analytes, they play an important role in many research fields [1,2,3,4,5]
We report about the surface plasmon resonance (SPR) sensor's performances variation when the photoresist buffer layer changes
The measurements were performed by using different water-glycerin solutions, with refractive index ranging from 1.332 to 1.393 as displayed

Summary

Introduction

Surface plasmon resonance bio–chemical sensors in optical fibers are suitable for on-site and real-time monitoring of different analytes, they play an important role in many research fields [1,2,3,4,5]. The improvement of the sensitivity with the aim to observe small variations of refractive index of the analyte under investigation is one of the critical point to be addressed [6]. In the SPR D–shaped POF sensors described in this work the use of a buffer layer based on photoresist is a successful solution for increasing the sensitivity of the device. The selection of the photoresist depends on the specific application and on the region of refractive index of interest [11]. The SPR sensing platforms were fabricated by removing the cladding of a POF along half circumference, spin coating on the exposed core a buffer layer of photoresist, and sputtering a thin gold film [8]. We report about the SPR sensor's performances variation when the photoresist buffer layer changes.

Plasmonic POF Sensors

Results

Conclusions