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Publicações

Publicações por Susana Novais

2019

Humidity sensor based on optical fiber coated with agarose gel

Autores
Novais, S; Ferreira, MS; Pinto, JL;

Publicação
Optical Sensors 2019

Abstract

2019

Internal strain and temperature discrimination with optical fiber hybrid sensors in Li-ion batteries

Autores
Nascimento, M; Novais, S; Ding, MS; Ferreira, MS; Koch, S; Passerini, S; Pinto, JL;

Publicação
JOURNAL OF POWER SOURCES

Abstract
Strain and temperature are critical parameters to monitor in Li-ion batteries (LIBs) to improve their safety and long-term cycling stability. High local current densities can result in a massive heat release, decomposition of the electrolyte, gas evolution and even explosion of the battery cell, known as thermal runaway. However, the corrosive chemical environment in the batteries is a challenge to monitor strain and temperature. Optical fiber sensors, due to their high chemical stability and small diameter, can be embedded within the LIBs, thus becoming an interesting solution for operando and in situ measurements. In this work, a hybrid sensing network constituted by fiber Bragg gratings and Fabry-Perot cavities is proposed for the discrimination of strain and temperature. The proof-of-concept was performed by attaching the sensing network to the surface of a smart phone battery. Afterwards, it was embedded in a Li-ion pouch cell to monitor and simultaneously discriminate internal strain and temperature variations in three different locations. Higher thermal and strain variations are observed in the middle position. The methodology presented proves to be a feasible and non-invasive solution for internal, real-time, multipoint and operando temperature and strain monitoring of LIBs, which is crucial for their safety.

2019

A Self-Referencing Intensity-Based Fabry–Perot Cavity for Curvature Measurement

Autores
Novais, S; Silva, SO; Frazao, O;

Publicação
IEEE Sensors Letters

Abstract

2019

Fabry-Perot cavity for curvature measurement in a medical needle

Autores
Novais, S; Silva, SO; Frazão, O;

Publicação
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
A reflective fiber optic sensor based on a Fabry-Perot cavity made by splicing two sections of multimode fiber is demonstrated to measure the needle curvature. The sensing structure was incorporated into a medical needle and characterized for curvature and temperature measurements. The maximum sensitivity of-0.152dB/m-1 was obtained to the curvature measurements, with a resolution of 0.089m-1. When subjected to temperature, the sensing head presented a low temperature sensitivity, which resulted in a small cross-sensitivity. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

2019

Multiplexing optical fiber Fabry-Perot interferometers based on air-microcavities

Autores
Pérez Herrera, RA; Novais, S; Bravo, M; Leandro, D; Silva, S; Frazao, O; Lopez Amo, M;

Publicação
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
In this work we demonstrate the multiplexing capability of new optical fiber Fabry-Perot interferometers based on airmicrocavities using a commercial FBG interrogator. Three optimized air-microcavity interferometer sensors have been multiplexed in a single network and have been monitored using the commercial FBGs interrogator in combination with FFT calculations. Results show a sensitivity of 2.18 p rad/m? and a crosstalk-free operation. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.