Repositório Colecção: Artigos em Revistas InternacionaisArtigos em Revistas Internacionaishttps://hdl.handle.net/1822/12792024-03-28T16:46:28Z2024-03-28T16:46:28ZLow-cost/high-reproducibility flexible sensor based on photonics for strain measuringRocha, R. P.Gomes, M. J.Carmo, João Paulo PereiraFerreira da Silva, AlexandreCorreia, J. H.https://hdl.handle.net/1822/899842024-03-25T21:02:13ZTítulo: Low-cost/high-reproducibility flexible sensor based on photonics for strain measuring
Autor: Rocha, R. P.; Gomes, M. J.; Carmo, João Paulo Pereira; Ferreira da Silva, Alexandre; Correia, J. H.
Resumo: This paper presents a flexible sensor based on photonics for measuring strain, curvatures and vibrations. This flexible sensor is composed by a Fiber Bragg Grating (FBG) embedded into polydimethylsiloxane (PDMS). The selected FBG resonates at the wavelength of 1552.37 nm and is embedded before the curing for enabling a strong adhesion between both components. Few prototypes were fabricated and characterized. The measurements showed a maximum strain sensitivity of approximate to 400 pm per 1% elongation, revealing to be sensitive to strain/bending forces and vibration. The measurements allowed to establish a predictable response for both static and dynamic behavior, corresponding to a resolution of approximate to 88 pm per curvature degree. This flexible sensor also allowed high strain cycles and presented the linear behavior of approximate to 14 pm degrees C-1 over the temperature range 20-110 degrees C. The high-simplicity of the fabrication process results on low-cost with high-degree of reproducibility of their characteristics. (C) 2013 Elsevier Ltd. All rights reserved.
<b>Tipo</b>: articleFabrication and mechanical characterization of long and different penetrating length neural microelectrode arraysGonçalves, Sandra Beatriz ToméPeixoto, Alexandre Coumiotis MoreiraFerreira da Silva, AlexandreCorreia, J. H.https://hdl.handle.net/1822/899742024-03-25T20:58:42ZTítulo: Fabrication and mechanical characterization of long and different penetrating length neural microelectrode arrays
Autor: Gonçalves, Sandra Beatriz Tomé; Peixoto, Alexandre Coumiotis Moreira; Ferreira da Silva, Alexandre; Correia, J. H.
Resumo: This paper presents a detailed description of the design, fabrication and mechanical characterization of 3D microelectrode arrays (MEA) that comprise high aspect-ratio shafts and different penetrating lengths of electrodes (from 3 mm to 4 mm). The array's design relies only on a bulk silicon substrate dicing saw technology. The encapsulation process is accomplished by a medical epoxy resin and platinum is used as the transduction layer between the probe and neural tissue. The probe's mechanical behaviour can significantly affect the neural tissue during implantation time. Thus, we measured the MEA maximum insertion force in an agar gel phantom and a porcine cadaver brain. Successful 3D MEA were produced with shafts of 3 mm, 3.5 mm and 4 mm in length. At a speed of 180 mm min(-1), the MEA show maximum penetrating forces per electrode of 2.65 mN and 12.5 mN for agar and brain tissue, respectively. A simple and reproducible fabrication method was demonstrated, capable of producing longer penetrating shafts than previously reported arrays using the same fabrication technology. Furthermore, shafts with sharp tips were achieved in the fabrication process simply by using a V-shaped blade.
<b>Tipo</b>: articleLarge-scale colloidal synthesis of chalcogenides for thermoelectric applicationsSousa, VivianaSarkar, ArkaLebedev, Oleg ICandolfi, ChristopheLenoir, BertrandCoelho, RodrigoGonçalves, António PVieira, E. M. FAlpuim, P.Kovnir, KirillKolen'ko, Yury Vhttps://hdl.handle.net/1822/899552024-03-25T20:45:00ZTítulo: Large-scale colloidal synthesis of chalcogenides for thermoelectric applications
Autor: Sousa, Viviana; Sarkar, Arka; Lebedev, Oleg I; Candolfi, Christophe; Lenoir, Bertrand; Coelho, Rodrigo; Gonçalves, António P; Vieira, E. M. F; Alpuim, P.; Kovnir, Kirill; Kolen'ko, Yury V
Resumo: A simple and effective preparation of solution-processed chalcogenide thermoelectric materials is described. First, PbTe, PbSe, and SnSe were prepared by gram-scale colloidal synthesis relying on the reaction between metal acetates and diphenyl dichalcogenides in hexadecylamine solvent. The resultant phase-pure chalcogenides consist of highly crystalline and defect-free particles with distinct cubic-, tetrapod-, and rod-like morphologies. The powdered PbTe, PbSe, and SnSe products were subjected to densification by spark plasma sintering (SPS), affording dense pellets of the respective chalcogenides. Scanning electron microscopy shows that the SPS-derived pellets exhibit fine nano-/micro-structures dictated by the original morphology of the key constituting particles, while the powder X-ray diffraction and electron microscopy analyses confirm that the SPS-derived pellets are phase-pure materials, preserving the structure of the colloidal synthesis products. The resultant solution-processed PbTe, PbSe, and SnSe exhibit low thermal conductivity, which might be due to the enhanced phonon scattering developed over fine microstructures. For undoped n-type PbTe and p-type SnSe samples, an expected moderate thermoelectric performance is achieved. In contrast, an outstanding figure-of-merit of 0.73 at 673 K was achieved for undoped n-type PbSe outperforming, the majority of the optimized PbSe-based thermoelectric materials. Overall, our findings facilitate the design of efficient solution-processed chalcogenide thermoelectrics.
<b>Tipo</b>: articleDesign and characterization of an active compression garment for the upper extremityGoncalves, CarlosFerreira da Silva, AlexandreSimões, Ricardo João FerreiraGomes, JoãoStirling, LeiaHolschuh, Bradhttps://hdl.handle.net/1822/899292024-03-25T21:01:18ZTítulo: Design and characterization of an active compression garment for the upper extremity
Autor: Goncalves, Carlos; Ferreira da Silva, Alexandre; Simões, Ricardo João Ferreira; Gomes, João; Stirling, Leia; Holschuh, Brad
Resumo: This paper presents the design, development, and testing of an active textile-based wearable compression device that is capable of delivering a controlled pulsatile compression. The device uses low spring index nickel titanium (NiTi) coil actuators to produce an applied dynamic pressure of up to 5.5 kPa. The selected NiTi coil actuators produce pressure when thermally stimulated with Joule heating via an applied current (0.3 A), and generate recoverable strains up to 75% in extension. An optical fiber strain sensor was developed to monitor the textile strain and enable the indirect estimation of the applied pressure. A new approach using a passive NiBR spring (in parallel with the NiTi actuators) was also developed to assist the NiTi coils in recovering the detwinned martensite form after cooling. The pressure distribution around a rigid cylindrical shape was also evaluated, showing higher applied pressures (5.5 kPa) where the NiTi coil actuators were located. The strain sensor exhibits high accuracy compared to a reference commercial sensor (as indicated by the high correlation indexes of up to 0.97 between compression cycle measurements with both solutions).
<b>Tipo</b>: articleSmart vest for real-time postural biofeedback and ergonomic risk assessmentCerqueira, Sara Maria Brito AraújoFerreira da Silva, AlexandreSantos, Cristinahttps://hdl.handle.net/1822/899222024-03-25T10:01:30ZTítulo: Smart vest for real-time postural biofeedback and ergonomic risk assessment
Autor: Cerqueira, Sara Maria Brito Araújo; Ferreira da Silva, Alexandre; Santos, Cristina
Resumo: Work-related musculoskeletal disorders (WRMSDs) are a serious worldwide health concern, that can result in the worker's permanent disability and an economic burden of up to 2% of the Gross Domestic Product (GDP). This paper presents the design and development of an innovative smart garment for real-time ergonomic risk assessment. It aims to empower operators with posture awareness and provide objective data to ergonomists. The system is based on inertial sensors and implements a biofeedback strategy that uses haptic stimulus to warn the user about hazard postures, enabling more ergonomic postures. To allow an easy data analysis, a graphical interface was developed in MATLAB. This framework was validated with 5 subjects, in a simulated scenario with 5 tasks that included a collaborative robot arm. The results showed that providing real-time biofeedback to the subject improves posture awareness, and has a significant impact on reducing the ergonomic risk, with reductions of up to 39.8% of the time spent in hazard postures. The wearable technology and developed methodologies are a promising tool to complement the ergonomist diagnoses of hazard tasks and workspaces and to reduce the risk of musculoskeletal disorders.
<b>Tipo</b>: article