Stabilization of Polymeric Nanofibers Layers for Use as Real-Time and In-Flow Photonic Sensors.

Salvador Ponce-Alcántara,Jaime García-Rupérez,Paula Martínez-Pérez,Jon Maudes,Nieves Murillo,Ana Pérez-Márquez

doi:10.3390/s19183847

Salvador Ponce-Alcántara, Jaime García-Rupérez + Show 4 more

Open Access

https://doi.org/10.3390/s19183847

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Abstract

In order to increase the sensitivity of a sensor, the relationship between its volume and the surface available to be functionalized is of great importance. Accordingly, porous materials are becoming very relevant, because they have a notable surface-to-volume ratio. Moreover, they offer the possibility to infiltrate the target substances on them. Among other porous structures, polymeric nanofibers (NFs) layers fabricated by electrospinning have emerged as a very promising alternative to low-cost and easy-to-produce high-performance photonic sensors. However, experimental results show a spectrum drift when performing sensing measurements in real-time. That drift is responsible for a significant error when trying to determine the refractive index variation for a target solution, and, because of that, for the detection of the presence of certain analytes. In order to avoid that problem, different chemical and thermal treatments were studied. The best results were obtained for thermal steps at 190 °C during times between 3 and 5 h. As a result, spectrum drifts lower than 5 pm/min and sensitivities of 518 nm/refractive index unit (RIU) in the visible range of the spectrum were achieved in different electrospun NFs sensors.

Highlights

In the race to provide high-sensitivity sensors with a reduced response time and price, photonics is becoming a notable option to be taken into account
5 pm/min and sensitivities of 518 nm/refractive index unit (RIU) in the visible range of the spectrum were achieved in different electrospun NFs sensors
A change in the sensing medium leads to a variation of the evanescent field properties, which are translated into a change of the effective refractive index [7,8]

Summary

Introduction

In the race to provide high-sensitivity sensors with a reduced response time and price, photonics is becoming a notable option to be taken into account. In this respect, the use of optical sensors provides important advantages compared to other technologies, including a small size, a light weight, high sensitivity, a shorter time-to-result, label-free detection, a requirement for very low volumes of sample and reagents, resistance to hazardous and harsh environments, and immunity to electromagnetic interference [1]. We can distinguish between the guiding and the sensing (external) media In these sensors, the sensing measurement is based on the interaction of the evanescent part of a guided mode with the sensing medium.

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