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Projeto de investigação
Institute of Nanostructures, Nanomodelling and Nanofabrication
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Publicações
All-Standard-Cell-Based Analog-to-Digital Architectures Well-Suited for Internet of Things Applications
Publication . Correia, Ana; Tavares, Vítor Grade; Barquinha, Pedro; Goes, João; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; CTS - Centro de Tecnologia e Sistemas; DEE - Departamento de Engenharia Electrotécnica e de Computadores; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; MDPI - Multidisciplinary Digital Publishing Institute
In this paper, the most suited analog-to-digital (A/D) converters (ADCs) for Internet of Things (IoT) applications are compared in terms of complexity, dynamic performance, and energy efficiency. Among them, an innovative hybrid topology, a digital–delta (Δ) modulator (ΔM) ADC employing noise shaping (NS), is proposed. To implement the active building blocks, several standard-cell-based synthesizable comparators and amplifiers are examined and compared in terms of their key performance parameters. The simulation results of a fully synthesizable Digital-ΔM with NS using passive and standard-cell-based circuitry show a peak of 72.5 dB in the signal-to-noise and distortion ratio (SNDR) for a 113 kHz input signal and 1 MHz bandwidth (BW). The estimated (Formula presented.) is close to 16.2 fJ/conv.-step.
Fabrication of spatially-variable heterostructured CoCrFeMnNi high entropy alloy by laser processing
Publication . Shen, Jiajia; Choi, Yeon Taek; Yang, Jin; He, Jingjing; Zeng, Zhi; Zhou, N.; Baptista, A. C.; Kim, Hyoung Seop; Oliveira, J. P.; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier
This study investigates the fabrication of spatially-variable heterostructured CoCrFeMnNi high entropy alloy (HEA) using pulsed laser processing. Two distinct fabrication approaches, involving single-(SP) and double-sided (DP) laser passes, were employed. Microstructural characterization through electron backscatter diffraction revealed significant differences. SP-HEA exhibited a spatially heterogeneous microstructure with coarse columnar grains, while DP-HEA displayed a sandwich-like structure with fine equiaxed recrystallized grains. Microhardness mapping demonstrated a gradient trend in SP-HEA, with the fusion zone exhibiting the lowest hardness and the base material the highest. In contrast, DP-HEA displayed an overall soft-hard-soft structure. Tensile testing revealed distinct mechanical responses, with DP-HEA exhibiting higher strength and ductility compared to SP-HEA. The improved performance of DP-HEA was attributed to a more uniform distribution of heterogeneity, minimizing mechanical interactions between soft and hard domains. Moreover, corrosion resistance was assessed, showing that DP-HEA outperformed SP-HEA and non-processed material, suggesting superior stability in corrosive environments. These findings highlight the profound influence of fabrication parameters on the microstructure and mechanical properties of spatially-variable heterostructured HEAs. The study contributes valuable insights for material design and applications based on CoCrFeMnNi high entropy alloys.
On the orientation-dependent mechanical properties of interstitial solute-strengthened Fe49.5Mn30Co10Cr10C0.5 high entropy alloy produced by directed energy deposition
Publication . Chabok, Ali; Zhang, Wei; Shen, Jiajia; Oliveira, J. P.; Wang, Hui; Feng, Shaochuan; Schell, Nobert; Kooi, Bart J.; Pei, Yutao; DEMI - Departamento de Engenharia Mecânica e Industrial; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier
Interstitial solute-strengthened Fe49.5Mn30Cr10Co10C0.5 (at%) high entropy alloy was additively manufactured by directed energy deposition (DED) process in this work. While the as-deposited material exhibits an excellent combination of strength and ductility, the effect of anisotropy on the mechanical performance of the DED processed component was studied in detail. The ultimate tensile strength (UTS) of the horizontal tensile sample with a main fiber texture of <111> // tensile direction (TD) went up to 1 GPa while maintaining a superb failure elongation of 36%. The vertical tensile sample, with a dominant <001> // TD texture, failed at an UTS of 750 MPa with an enhanced failure elongation of 52%. Microstructural analysis of the deformed samples showed that the horizontal samples were mainly deformed via the formation of mechanical twins, whereas the twining activity was less profound in the vertical samples. Single crystal micro-pillar compression testing revealed that the deformation mechanism complies well with the Schmid's factor. In addition, a higher critical resolved shear stress for twining compared to slip was also confirmed in the micro-pillar compression testing.
Preparation and characterization of porous scaffolds based on poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
Publication . Esmail, Asiyah; Pereira, João R.; Sevrin, Chantal; Grandfils, Christian; Menda, Ugur Deneb; Fortunato, Elvira; Oliva, Abel; Freitas, Filomena; DQ - Departamento de Química; UCIBIO - Applied Molecular Biosciences Unit; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Programme in Translational Medicine (iNOVA4Health); MDPI - Multidisciplinary Digital Publishing Institute
Poly(hydroxyalkanoates) (PHAs) with different material properties, namely, the homopolymer poly(3-hydroxybutyrate), P(3HB), and the copolymer poly(3-hydroxybutyrate-co-3- hydroxyvalerate, P(3HB-co-3HV), with a 3HV of 25 wt.%, were used for the preparation of porous biopolymeric scaffolds. Solvent casting with particulate leaching (SCPL) and emulsion templating were evaluated to process these biopolymers in porous scaffolds. SCPL scaffolds were highly hydrophilic (>170% swelling in water) but fragile, probably due to the increase of the polymer’s polydispersity index and its high porosity (>50%). In contrast, the emulsion templating technique resulted in scaffolds with a good compromise between porosity (27–49% porosity) and hydrophilicity (>30% water swelling) and without impairing their mechanical properties (3.18–3.35 MPa tensile strength and 0.07–0.11 MPa Young’s Modulus). These specifications are in the same range compared to other polymer-based scaffolds developed for tissue engineering. P(3HB-co-3HV) displayed the best overall properties, namely, lower crystallinity (11.3%) and higher flexibility (14.8% elongation at break. Our findings highlight the potency of our natural biopolyesters for the future development of novel porous scaffolds in tissue engineering, thanks also to their safety and biodegradability.
A simple polystyrene microfluidic device for sensitive and accurate SERS-based detection of infection by malaria parasites
Publication . Oliveira, Maria João; Caetano, Soraia; Dalot, Ana; Sabino, Filipe; Calmeiro, Tomás R.; Fortunato, Elvira; Martins, Rodrigo; Pereira, Eulália; Prudêncio, Miguel; Byrne, Hugh J.; Franco, Ricardo; Águas, Hugo; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; RSC - Royal Society of Chemistry
Early and accurate detection of infection by pathogenic microorganisms, such as Plasmodium, the causative agent of malaria, is critical for clinical diagnosis and ultimately determines the patient's outcome. We have combined a polystyrene-based microfluidic device with an immunoassay which utilises Surface-Enhanced Raman Spectroscopy (SERS) to detect malaria. The method can be easily translated to a point-of-care testing format and shows excellent sensitivity and specificity, when compared to the gold standard for laboratorial detection of Plasmodium infections. The device can be fabricated in less than 30 min by direct patterning on shrinkable polystyrene sheets of adaptable three-dimensional microfluidic chips. To validate the microfluidic system, samples of P. falciparum-infected red blood cell cultures were used. The SERS-based immunoassay enabled the detection of 0.0012 ± 0.0001% parasitaemia in a P. falciparum-infected red blood cell culture supernatant, an ∼7-fold higher sensitivity than that attained by most rapid diagnostic tests. Our approach successfully overcomes the main challenges of the current Plasmodium detection methods, including increased reproducibility, sensitivity, and specificity. Furthermore, our system can be easily adapted for detection of other pathogens and has excellent properties for early diagnosis of infectious diseases, a decisive step towards lowering their high burden on healthcare systems worldwide.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/50025/2020