2019
Authors
Novais, S; Silva, SO; Frazão, O;
Publication
IEEE Sensors Letters
Abstract
2019
Authors
Novais, S; Silva, SO; Frazao, O;
Publication
SEVENTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS (EWOFS 2019)
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
Authors
Perez Herrera, RA; Novais, S; Bravo, M; Leandro, D; Silva, SF; Frazao, O; Lopez Amo, M;
Publication
SEVENTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS (EWOFS 2019)
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
Authors
Novais, S; Silva, SO; Frazao, O;
Publication
MEASUREMENT
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
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
Authors
Roriz, P; Silva, S; Frazao, O; Novais, S;
Publication
SENSORS
Abstract
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