2022
Authors
Dias, B; De Almeida, JMMM; Coelho, LCC;
Publication
Journal of Physics: Conference Series
Abstract
Bloch Surface Waves (BSW) consist of electromagnetic modes generated at the interface between a photonic crystal and an isotropic dielectric. This type of surface mode displays sharp resonances and high sensitivity to external refractive index variations, and thus appears to be an ideal candidate for usage in optical sensors. Nevertheless, design and optimization of photonic crystals is not a trivial task and constitutes an ongoing field of research. The sensitivity of BSW in both refractometric and adsorption sensing is calculated analytically using first-order perturbation theory for TE modes, allowing the understanding of how several physical parameters of the photonic crystal influence the sensitivity. Preliminary experimental results are presented, which aim to use the analytical calculations to allow for both refractometric and adsorption sensing in a single photonic crystal structure. © Published under licence by IOP Publishing Ltd.
2022
Authors
Dos Santos, PSS; Mendes, J; Dias, B; Pastoriza Santos, I; De Almeida, JMMM; Coelho, LCC;
Publication
Journal of Physics: Conference Series
Abstract
New paths to increase the sensing performance of plasmonic sensors have been reported in recent years. There are several methodologies to achieve such purpose, namely by optimizing the nanostructure, nanomaterial and even the sensing platform. Recently the use nanoparticles over plasmonic thin films have been reported and shown sensitivity enhancement, when compared to a bare thin film. Nevertheless, a nanomaterial combination between NP and thin film has not been studied. In this work it was studied such plasmonic materials in order to optimize not only refractometric sensitivity but also decrease the resultant plasmonic band width. It was found that for Au, Ag and Cu thin films, the deposition of plasmonic nanoparticles resulted in an overall refractometric sensitivity and figure of merit (FOM) increase. The larger FOM increase was obtained for the Ag thin film, from 42 to 162 when coupled to Si nanoparticles. The greater sensitivity increase was achieved for a Cu thin film coupled to a Si nanoparticle, with an increase from 1745 to 3230 nm/RIU. © Published under licence by IOP Publishing Ltd.
2022
Authors
Araújo, JCC; Dias, B; Dos Santos, PSS; De Almeida, JMMM; Coelho, LCC;
Publication
Journal of Physics: Conference Series
Abstract
The interrogation of optic fiber sensors usually relies in complex and costly equipment with low portability due to their size such as Optical Spectrum Analyzers (OSA) or high-resolution spectrometers. Because of this, micro spectrometer devices, such as Micro-Electromechanical Systems (MEMS) with Fabry-Pérot tunable filters, are emerging as simpler and compact alternatives capable of being used to acquire spectral information in a wide wavelength band. In this work it is described the development of an interrogation system capable of infrared spectroscopy using a MEMS Fabry-Pérot Interferometer (MEMS-FPI) with a spectral response in the 1350nm to 1650nm range. Its performance is tested with the interrogation of long period fiber gratings both as a refractive index sensor and as a temperature sensor. Deconvolution techniques such as Wiener filtering are used to reduce the impact of the tunable filter's impulse response in the measured signal. Results are comparable to those obtained using a typical OSA which shows the system's potential as a cheaper and more transportable alternative. © Published under licence by IOP Publishing Ltd.
2022
Authors
Mendes, J; Lima, J; Costa, L; Rodrigues, N; Brandao, D; Leitao, P; Pereira, AI;
Publication
OPTIMIZATION, LEARNING ALGORITHMS AND APPLICATIONS, OL2A 2022
Abstract
The identification of olive-tree cultivars is a lengthy and expensive process, therefore, the proposed work presents a new strategy for identifying different cultivars of olive trees using their leaf and machine learning algorithms. In this initial case, four autochthonous cultivars of the Tras-os-Montes region in Portugal are identified (Cobrancosa, Madural, Negrinha e Verdeal). With the use of this type of algorithm, it is expected to replace the previous techniques, saving time and resources for farmers. Three different machine learning algorithms (Decision Tree, SVM, Random Forest) were also compared and the results show an overall accuracy rate of the best algorithm (Random Forest) of approximately 93%.
2022
Authors
Pessanha, S; Silva, AL; Guimaraes, D;
Publication
X-RAY SPECTROMETRY
Abstract
2022
Authors
Navarro Medina, F; Aguado Agelet, F; Garcia Luis, U; Ulloa, C; Orgeira Crespo, P; Camanzo Mariño, A; Dragos Darau, V; Maia, MM; Gomez San Juan, A; Furtado, C; Machado, V; Califórnia, A; Bogas, S; Ferreira, C; Silva, J; Sousa, L; Machado, J; Roy, P; Auguste, J; Jamier, R; Leconte, B; Frazão, O; Robalinho, P; Pires, AL; Roacha, M; Comesaña, R; Pereira, AM;
Publication
Proceedings of the International Astronautical Congress, IAC
Abstract
Given the fact that CubeSats are becoming an alternative for accessible, reduced-risk development for space applications within an emergent technological market and that the power demand of these type of nanosatellites is increasing due to the complexity of the defined missions, an alternative solution to traditional energy harvesting systems (i.e., solar panels and batteries) is proposed within the WiPTherm project. Being a high-risk category (FET-Future and Emerging Technologies) project within the H2020 European funding scheme, it aims to provide a Wireless Energy Transfer solution via a photo-thermoelectric plasmonic (HPTP) generator array device that can convert photonic energy to electrical energy via thermal gradient. In order to create it, a long-range, continuous-wave (CW) laser source targets the cells of the HPTP generator, forming, as such, the photo-thermoelectric plasmonic system. Two possible scenarios were taken into account and presented in terms of mission requirements: the laser source charging the satellite from Earth, or a laser system mounted onto a master satellite charging a CubeSat orbiting Mars/Jupiter, within the context of a deep space mission. The development of such Wireless Energy Transfer (WET) system implies an improvement of the current technology in different research fields, among them: nanomaterials, photonics, electronics, and space systems. For the success of the project, all of them shall be developed considering the different interfaces as well as the assembly principles, to be compatible with the support structure: a 3U CubeSat. From the Assembly, Integration and Verification (AIV) plan point of view, a testing philosophy involving different models is presented: an STM of the complete 3U CubeSat for the development of higher-fidelity tests when evaluating both structural and thermal HPTP baseplate capabilities; an Engineering Model, where all the subsystems will be assembled on the CubeSat platform and all its functionalities tested; development models for all spacecraft subsystems that are new developments and are not off the shelf: HPTP, the CubeSat electrical module and the laser generator. As a conclusion, this work presents the concept beyond the technology herein purposed, its applicability, and, from the systems engineering point of view, the challenges faced on the AIV plan. © 2022 International Astronautical Federation, IAF. All rights reserved.
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