Continuous Measurement With Three-in-One Plasmon Sensor in Sucrose Solutions

Abstract

Surface plasmons are a revolution in nanophotonics because they permit the transport of energy along metal-dielectric interfaces, something which is of vital importance in sensors which measure refractive indexes. The aim of this research has been the design and optimization of several surface plasmon resonance (SPR) sensors to measure the refractive index of a solution of sucrose and water (BRIX degree) in real time. The optimization and design of these sensors was made from the theoretical modelling of the reflectance curves, which has allowed us to determine which the most favourable configuration is. The sensors proposed are modulated in intensity and they have the advantage of not having mobile parts, so, their lifetime is longer. We propose a plasmonic sensors (three-in-one) for measuring different sucrose concentrations. As the refractive indexes vary very little with the concentration, we have designed a three-in-one sensor to cover all concentrations from 0-80% BRIX degree. The proposed sensors operate by ranges of refractive indexes (low, medium and high). They are made up of a hemispherical prism and a layer of gold following the Kretschmann configuration. The sensor working in the low zone has a sensitivity of between 22.95 and 4.64RIU−1 and a resolution of between 4.3×10−4 and 8.7×10−5 RIU, the one used for the medium zone has a sensitivity of between 21.05 and 3.89RIU−1 and a resolution of between 5.1×10−4 and 9.5×10−5 RIU, and the one for the high zone has a sensitivity of between 19.60 and 4.64RIU−1 and a resolution of between 4.3×10−4 and 1.0×10−4 RIU.