2023
Authors
Alves, T; Rodrigues, C; Callaty, C; Duarte, C; Ventura, J;
Publication
ADVANCED MATERIALS TECHNOLOGIES
Abstract
The increasing use of wearable electronics calls for sustainable energy solutions. Biomechanical energy harvesting appears as an attractive solution to replace the use of batteries in wearables, as the body generates sufficient power to drive small electronics. In particular, triboelectric nanogenerators (TENGs) have emerged as a promising approach due to its lightweight and high power density. In this work, a TENG is hybridized with an electromagnetic generator (EMG) to harvest energy from the foot strike. An enclosed radial-flow turbine is optimized and used to convert the foot-strike low-frequency linear movement into a higher-frequency rotational motion (by a factor of & AP;12). Besides increasing the motion frequency, the employed mechanism is physically robust and enables a continuous operation from irregular mechanical excitations. A single TENG unit operating in the freestanding mode generated an optimal power of 4.72 & mu;W and transferred a short-circuit charge of 2.3 nC. The TENG+EMG hybridization allows to power a digital pedometer even after the mechanical input stopped. Finally, the energy harvester is incorporated into a commercial shoe to power the same pedometer from foot walking. The obtained results validate the developed prototype ability to serve as a portable power source that can drive sensors and wearable electronics.
2012
Authors
Duarte, C; Cavadas, H; Coke, P; Malheiro, L; Tavares, VG; de Oliveira, PG;
Publication
2012 17TH IEEE EUROPEAN TEST SYMPOSIUM (ETS)
Abstract
This work addresses a built-in self-test methodology for circuit cell identification under specific matching conditions. The proposed technique is applied to the CMOS realization of a reduced-KII network, which is a system model of the biological olfactory cortex. This model behaves as an associative memory, a useful tool for information and adaptive processes. Based on a mixed-signal approach, the test strategy makes proper use of the circuits comprising the network structure, and provides self reconfiguration as well. Both testing procedures and design of essential building blocks are described in this paper. Simulation results are presented for a reduced-KII network comprising 128-cells, sequentially tested for matching in terms of offsets and their dynamic performances.
2012
Authors
Duarte, C; Oliveira, HP; Magalhães, F; Tavares, VG; Campilho, AC; de Oliveira, PG;
Publication
Proceedings of the IEEE Global Engineering Education Conference, EDUCON 2012, Marrakech, Morocco, April 17-20, 2012
Abstract
This paper presents two initiatives run by groups of engineering students at the University of Porto: the Microelectronics Students' Group and BioStar. These groups are student-led initiatives that promote different scientific fields through self-guided projects. Both experiences have proven to be very successful in increasing the undergraduate student's interest in science and technology. This work reports the activities, organization and main methodologies employed by these groups, which can be seen as successful approaches to enhance the technical curriculum of students. © 2012 IEEE.
2012
Authors
Bahubalindruni, G; Duarte, C; Tavares, VG; Barquinha, P; Martins, R; Fortunato, E; de Oliveira, PG;
Publication
2012 20TH TELECOMMUNICATIONS FORUM (TELFOR)
Abstract
This paper presents the results of a preliminary study to examine the ability of post-silicon devices for analog processing. It is focused on the latest thin-film transistors (TFTs) with amorphous gallium-indium-zinc oxide (a-GIZO) as active layer. Three circuit configurations are presented: a differential pair and two multiplier topologies. Both triode and saturation regions of operation are included in the analysis, with the devices set to remain in strong accumulation. A neural model, which is developed based on the measured data of the TFTs, is used for the circuit simulations in the Cadence Virtuoso environment. The analog multipliers simulation results are compared against the expected functional results.
2012
Authors
Bahubalindruni, G; Tavares, VG; Barquinha, P; Duarte, C; Martins, R; Fortunato, E; De Oliveira, PG;
Publication
2012 International Conference on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design, SMACD 2012
Abstract
This paper addresses a modeling and simulation methodology for analog circuit design with amorphous-GIZO thin-film transistors (TFTs). To reach an effective circuit design flow, with commercially available tools, a TFT model has been first developed with an artificial neural network (ANN). Multilayer perceptron with backpropagation algorithm has been adopted to model the static behavior of the TFT devices, for different aspect ratios. The model was then implemented in Verilog-A, to allow a quick instantiation in circuit. Simulations using Cadence Spectre are performed to validate the model. On a second phase, simulation results of basic analog circuits, with this ANN model, are verified against the actual functional results, namely an adder, subtractor, and current mirror circuit. Results demonstrate not only the ANN model accuracy and compatibility with dc and transient analysis, but also show the a-GIZO TFT capability to perform analog operations. © 2012 IEEE.
2011
Authors
Coke, P; Duarte, C; Cardoso, A; Tavares, VG; De Oliveira, PG;
Publication
EUROCON 2011 - International Conference on Computer as a Tool - Joint with Conftele 2011
Abstract
This paper presents an initiative to involve ECE undergraduate students in the design and deployment of a network infrastructure for an academic laboratory. The project aims at attaining a reliable and secure network for an IC CAD environment. The students focused on employing secure authentication, accounting and storage with single sign-on, based on enterprise-grade, open-source protocols. This initiative proved to be highly motivating and allowed the students to develop knowledge and hands-on experience on the area of network security. The resulting network design and core infrastructure is herein described as well as its deployment in a real microelectronics design environment. © 2011 IEEE.
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