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Publications

Publications by Susana Novais

2019

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

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

Publication
IEEE Sensors Letters

Abstract

2019

Fabry-Perot cavity for curvature measurement in a medical needle

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

Publication
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

Authors
Perez Herrera, RA; Novais, S; Bravo, M; Leandro, D; Silva, SF; Frazao, O; Lopez Amo, M;

Publication
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.

2020

Curvature detection in a medical needle using a Fabry-Perot cavity as an intensity sensor

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

Publication
Measurement: Journal of the International Measurement Confederation

Abstract
The use of optical sensors inside the needle can improve targeting precision and can bring real-time information about the location of the needle tip if necessary, since a needle bends through insertion into the tissue. Therefore, the precise location of the needle tip is so important in percutaneous treatments. In the current experiment, a fiber sensor based on a Fabry-Perot (FP) cavity is described to measure the needle curvature. The sensor is fabricated by producing an air bubble between two sections of multimode fiber. The needle with the sensor therein was attached at one end and deformed by the application of movements. The sensor presents a sensitivity of -0.152 dB/m-1 to the curvature measurements, with a resolution of 0.089 m-1. The sensory structure revealed to be stable, obtaining a cross-sensitivity to be 0.03 m-1/°C. © 2019 Elsevier Ltd

2020

Detection of the Crystallization Process of Paracetamol with a Multi-Mode Optical Fiber in a Reflective Configuration

Authors
Soares, L; Novais, S; Ferreira, A; Frazao, O; Silva, S;

Publication
SENSORS

Abstract
A configuration of a refractometer sensor is described with the aim of optically detecting the crystallization process of paracetamol. The developed sensing head is based on a conventional cleaved multi-mode fiber. The fiber tip sensor structure was submitted to contact with the liquid of interest (paracetamol fully dissolved in 40% v/v of ethanol/water) and the crystallization process of paracetamol, induced with continued exposure to air, was monitored in real time.

2020

Optical Fiber Temperature Sensors and Their Biomedical Applications

Authors
Roriz, P; Silva, S; Frazao, O; Novais, S;

Publication
Sensors

Abstract
The use of sensors in the real world is on the rise, providing information on medical diagnostics for healthcare and improving quality of life. Optical fiber sensors, as a result of their unique properties (small dimensions, capability of multiplexing, chemical inertness, and immunity to electromagnetic fields) have found wide applications, ranging from structural health monitoring to biomedical and point-of-care instrumentation. Furthermore, these sensors usually have good linearity, rapid response for real-time monitoring, and high sensitivity to external perturbations. Optical fiber sensors, thus, present several features that make them extremely attractive for a wide variety of applications, especially biomedical applications. This paper reviews achievements in the area of temperature optical fiber sensors, different configurations of the sensors reported over the last five years, and application of this technology in biomedical applications.

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