2014
Authors
Oliveira, CC; Machado da Silva, J; Trindade, IG; Martins, F;
Publication
Proceedings of the 2014 29th Conference on Design of Circuits and Integrated Systems, DCIS 2014
Abstract
Wearable systems are expected to contribute for improving traditional biopotential signals monitoring devices due to higher freedom and unobtrusiveness provided to the wearer. Textile electrodes present advantages compared with the conventional Ag/AgCl electrodes for the capturing of biopotentials, namely in terms of skin irritation due to the hydrogel and the need of a technician to place the electrodes on the correct positions. Due to the lack of hydrogel, textile electrodes present different electrical contact characteristics. The skin-electrode impedance is an important feature since it affects the captured signal quality. Although a low impedance is desired, a comfortable wearable system should not require the electrodes to be covered by the hydrogel or be moistened. A forearm sleeve provided with textile electrodes was used to study the electrode-skin impedance and the signal-to-noise ratio (SNR) of surface electromyographic (EMG) signals on a long-term use basis. The sleeve can be adjusted for different levels of tightening to control the pressure applied on the electrodes. The obtained results provide valuable information on the pressure that the textile garments of a sleeve or vest should apply on the recording electrodes, in order to assure a good electrical and mechanical contact between the electrodes and the skin and decrease the noise due to motion. It was observed that the electrode-skin impedance measurement alone is not sufficient to establish a relation with the SNR. The extraction of parameters from an electrical equivalent model of the electrode-skin interface allows to determine a relation with the model parameters and the SNR. The evaluation of these parameters during long-term monitoring will allow assessing the quality of biopotential measurements in textile electrodes. © 2014 IEEE.
2014
Authors
Carvalho, JG; da Silva, JM;
Publication
2014 IEEE INTERNATIONAL SYMPOSIUM ON MEDICAL MEASUREMENTS AND APPLICATIONS (MEMEA)
Abstract
A transceiver for single-line communication among sensor nodes of a body-area network is presented. It is meant to operate on a mesh like network where nodes are interconnected by two conducting-textile lines, which provide both power and communication features. The textile conductors are sewn directly to the garment in order to enhance user's mobility and comfort. For the same reason, a single battery placed in a central processing module is used to supply all sensor nodes. A low-dropout voltage regulator supplied from the transmission-line via a low pass filter ensures in each node the respective 3 V DC power supply. Power-line-communication is performed using a binary phase shift keying modulation process over a non-zero direct current line voltage at a 10 Mbps rate. The transceiver includes also line-fault testing to detect hazards which are likely to occur due to the stress applied to the conductive yarns.
2014
Authors
Dias, R; da Silva, JM;
Publication
2014 11TH INTERNATIONAL CONFERENCE ON WEARABLE AND IMPLANTABLE BODY SENSOR NETWORKS WORKSHOPS (BSN WORKSHOPS)
Abstract
The work presented herein addresses the development, implementation, and evaluation of a new wearable system for monitoring bio-signals and physical human activity, namely for gait analysis and cardiovascular surveillance. It consists of a wearable textile substrate (pantyhose and/or T-shirt) with embedded conductive yarns interconnecting custom electronic devices, in a mesh or other network type, that acquire bio-signals and/or inertial data. All data are aggregated in a central processing module from where they are sent via a wireless link to a mobile phone or personal computer for final processing. The network topology, sensor nodes architecture and results obtained with first prototypes are presented.
2014
Authors
Zhang, SH; Li, X; Blanton, RD; da Silva, JM; Carulli, JM; Butler, KM;
Publication
2014 IEEE INTERNATIONAL TEST CONFERENCE (ITC)
Abstract
In this paper, a novel Bayesian model fusion (BMF) method is proposed for test cost reduction based on wafer-level spatial variation modeling. BMF relies on the assumption that a large number of wafers of the same circuit design (e.g., all wafers from the same lot) share a similar spatial pattern. Hence, the measurement data from one wafer can be borrowed to model the spatial variation of other wafers via Bayesian inference. By applying the Sherman-Morrison-Woodbury formula, a fast numerical algorithm is derived to reduce the computational cost of BMF for practical test applications. Furthermore, a new test methodology is developed based on BMF and it closely monitors the escape rate and yield loss. As is demonstrated by the wafer probe measurement data of an industrial RF transceiver, BMF achieves 1.125x reduction in test cost and 2.6x reduction in yield loss, compared to the conventional approach based on virtual probe (VP).
2014
Authors
Soares, C; Moreira, RS; Morla, R; Torres, J; Sobral, P;
Publication
FUTURE GENERATION COMPUTER SYSTEMS-THE INTERNATIONAL JOURNAL OF GRID COMPUTING AND ESCIENCE
Abstract
Commercial off-the-shelf devices and applications are expected to be pivotal in the coming massive deployment of pervasive computing technology in home settings. The integration of these devices and applications in the same household may result in unplanned interactions involving users and entertainment, communication, and health-related devices and applications. These unplanned interactions are a serious concern when, for example, communication or entertainment applications interfere with the behavior of health-related devices. This paper presents a novel graph-based approach for representing the expected behavior of commercial off-the-shelf devices and applications, their interactions, and for detecting interference in pervasive computing systems. A set of home care scenarios is used to assess the applicability of this approach. We then provide two setups where this approach can be applied: (i) in a pre-deployment setup, where simulation is used to detect possible instances of interference, and (ii) at run-time, collecting observations from devices and applications and detecting interference as it occurs. For pre-deployment and simulation we use Opensim to recreate a home household. For run-time, we use Simple Network Management Protocol for systems state introspection and a sliding window mechanism to process the collected data-stream. Crown Copyright
2014
Authors
Hussain, B; Kianpour, I; Tavares, VG; Mendonca, HS; Miskovic, G; Radosavljevic, G; Petrovic, VV;
Publication
2014 IEEE INTERNATIONAL CONFERENCE ON WIRELESS FOR SPACE AND EXTREME ENVIRONMENTS (WISEE)
Abstract
This paper presents a planar antenna using low temperature co-fired ceramics (LTCC) substrate for extreme environment applications. An ultra wideband (UWB) elliptical patch antenna was designed and fabricated using an LTCC Ceramtec GC substrate to demonstrate the capabilities of the technology for wideband applications. The simulated results were further validated experimentally. The fabricated antenna provides a peak gain of 5dB over a bandwidth of 4 GHz (3 GHz 7 GHz) with return loss better than -10dB. The radiation pattern is omni-directional in the horizontal plane (theta=90 degrees) over the whole frequency range.
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