Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

Publications by CAP

2016

Zinc oxide coated optical fiber long period gratings for sensing of volatile organic compounds

Authors
Coelho, L; Viegas, D; Santos, JL; de Almeida, JMMM;

Publication
OPTICAL SENSING AND DETECTION IV

Abstract
The detection of volatile organic compounds is accomplished with a sensing device based on a long period fiber grating (LPFG) coated with a zinc oxide (ZnO) thin layer with self-temperature compensation. The ZnO coating structure was produced onto the cladding of the fiber by thermal oxidation of a metallic Zn thin film. The morphological characterization of ZnO thin films, grown at the same time on silicon substrates, was performed using X-ray diffraction, X-ray Photoelectron Spectroscopy and Scanning Electron Microscope which shows very good agreement. LPFGs with 290 nm thick ZnO coating were fabricated and characterized for the detection of ethanol and hexane in vapor phase. For ethanol a sensitivity of 0.99 nm / g.m(-3) was achieved when using the wavelength shift interrogation mode, while for hexane a much lower sensitivity of 0.003 nm / g.m(-3) was measured, indicating a semi-selectivity of the sensor with a spectral resolution better than 3.2 g.m(-3).

2016

Design and Evaluation of Novel Textile Wearable Systems for the Surveillance of Vital Signals

Authors
Trindade, IG; da Silva, JM; Miguel, R; Pereira, M; Lucas, J; Oliveira, L; Valentim, B; Barreto, J; Silva, MS;

Publication
SENSORS

Abstract
This article addresses the design, development, and evaluation of T-shirt prototypes that embed novel textile sensors for the capture of cardio and respiratory signals. The sensors are connected through textile interconnects to either an embedded custom-designed data acquisition and transmission unit or to snap fastener terminals for connection to external monitoring devices. The performance of the T-shirt prototype is evaluated in terms of signal-to-noise ratio amplitude and signal interference caused by baseline wander and motion artefacts, through laboratory tests with subjects in standing and walking conditions. Performance tests were also conducted in a hospital environment using a T-shirt prototype connected to a commercial three-channel Holter monitoring device. The textile sensors and interconnects were realized with the assistance of an industrial six-needle digital embroidery tool and their resistance to wear addressed with normalized tests of laundering and abrasion. The performance of these wearable systems is discussed, and pathways and methods for their optimization are highlighted.

2016

MarinEye - A tool for marine monitoring

Authors
Martins, A; Dias, A; Silva, E; Ferreira, H; Dias, I; Almeida, JM; Torgo, L; Goncalves, M; Guedes, M; Dias, N; Jorge, P; Mucha, AP; Magalhaes, C; Carvalho, MDF; Ribeiro, H; Almeida, CMR; Azevedo, I; Ramos, S; Borges, T; Leandro, SM; Maranhao, P; Mouga, T; Gamboa, R; Lemos, M; dos Santos, A; Silva, A; Teixeira, BFE; Bartilotti, C; Marques, R; Cotrim, S;

Publication
OCEANS 2016 - SHANGHAI

Abstract
This work presents an autonomous system for marine integrated physical-chemical and biological monitoring - the MarinEye system. It comprises a set of sensors providing diverse and relevant information for oceanic environment characterization and marine biology studies. It is constituted by a physical-chemical water properties sensor suite, a water filtration and sampling system for DNA collection, a plankton imaging system and biomass assessment acoustic system. The MarinEye system has onboard computational and logging capabilities allowing it either for autonomous operation or for integration in other marine observing systems (such as Observatories or robotic vehicles. It was designed in order to collect integrated multi-trophic monitoring data. The validation in operational environment on 3 marine observatories: RAIA, BerlengasWatch and Cascais on the coast of Portugal is also discussed.

2016

Biosensor for label-free DNA quantification based on functionalized LPGs

Authors
Goncalves, HMR; Moreira, L; Pereira, L; Jorge, P; Gouveia, C; Martins Lopes, P; Fernandes, JRA;

Publication
BIOSENSORS & BIOELECTRONICS

Abstract
A label-free fiber optic biosensor based on a long period grating (LPG) and a basic optical interrogation scheme using off the shelf components is used for the detection of in-situ DNA hybridization. A new methodology is proposed for the determination of the spectral position of the LPG mode resonance. The experimental limit of detection obtained for the DNA was 62 +/- 2 nM and the limit of quantification was 209 +/- 7 nM. The sample specificity was experimentally demonstrated using DNA targets with different base mismatches relatively to the probe and was found that the system has a single base mismatch selectivity.

2016

Compact solutions for optical fiber tweezers using Fresnel Zone and Phase Lenses fabricated using FIB milling

Authors
Rodrigues Ribeiro, RSR; Dahal, P; Guerreiro, A; Jorge, PAS; Viegas, J;

Publication
COMPLEX LIGHT AND OPTICAL FORCES X

Abstract
In this work FZL and FPL fabricated using Focused Ion Beam milling on the top of custom-made optical fibers are presented. Primary, single mode fibers are spliced to a segment of multimode fiber allowing to expand the core region. Subsequently, FZL and FPL with several focusing distances are milled on the top of the fibers. In this regard, the zone and phase plates offer distinct focusing characteristics which are here presented and analyzed. Moreover, the output optical intensity field of the FPL and FZP are evaluated and validated using an implementation of the Finite Differences Time Domain (Lumerical). Lastly, some considerations on the use of the tips as fiber optical tweezers are given.

2016

Generation of Laguerre Gaussian beams using spiral phase diffractive elements fabricated on optical fiber tips using focused ion beam milling

Authors
Rodrigues Ribeiro, RSR; Dahal, P; Guerreiro, A; Jorge, PAS; Viegas, J;

Publication
COMPLEX LIGHT AND OPTICAL FORCES X

Abstract
In this work, spiral phase lenses fabricated on the tip of single mode optical fibers are reported. This allows tailoring the fundamental guided mode, a Gaussian beam, into a Laguerre - Gaussian profile without using additional optical elements. The lenses are fabricated using Focused Ion Beam milling, enabling high resolution in the manufacturing process. The phase profiles are evaluated and validated using an implementation of the Finite Differences Time Domain. The output optical intensity profiles matching the numerical simulations are presented and analyzed. Finally, results on cell trapping and manipulation are briefly described.

  • 83
  • 241