Larger and denser: an optimal design for surface grids of EMG electrodes to identify greater and more representative samples of motor units

The spinal motor neurons are the only neural cells whose individual activity can be non-invasively identified. This is usually done using grids of surface electromyographic (EMG) electrodes and source separation algorithms; an approach called EMG decomposition. In this study, we combined computational and experimental analyses to assess how the design parameters of grids of electrodes influence the number and the properties of the identified motor units. We first computed the percentage of motor units that could be theoretically discriminated within a pool of 200 simulated motor units when decomposing EMG signals recorded with grids of various sizes and interelectrode distances (IED). Increasing the density, the number of electrodes, and the size of the grids, increased the number of motor units that our decomposition algorithm could theoretically discriminate, i.e., up to 83.5% of the simulated pool (range across conditions: 30.5-83.5%). We then identified motor units from experimental EMG signals recorded in six participants with grids of various sizes (range: 2-36 cm2) and IED (range: 4-16 mm). The configuration with the largest number of electrodes and the shortest IED maximized the number of identified motor units (56±14; range: 39-79) and the percentage of early recruited motor units within these samples (29±14%). Finally, the number of identified motor units further increased with a prototyped grid of 256 electrodes and an IED of 2 mm. Taken together, our results showed that larger and denser surface grids of electrodes allow to identify a more representative pool of motor units than currently reported in experimental studies.Significance StatementThe application of source separation methods to multi-channel EMG signals recorded with grids of electrodes enables users to accurately identify the activity of individual motor units. However, the design parameters of these grids have never been discussed. They are usually arbitrarily fixed, often based on commercial availability. Here, we showed that using larger and denser grids of electrodes than conventionally proposed drastically increases the number of identified motor units. The samples of identified units are more balanced between early- and late-recruited motor units. Thus, these grids provide a more representative sampling of the active motor unit population. Gathering large datasets of motor units using large and dense grids will impact the study of motor control, neuromuscular modelling, and human-machine interfacing

Initiation à la conception d’antennes Yagi-Uda pour des lycéens

Dans le cadre des actions de sensibilisation vers l’enseignement secondaire du projet ANR FINMINA [2], une initiation à la conception d’antennes est proposée aux lycées de l’Académie de Rennes. Dans ce cadre, depuis 2016, plusieurs groupes d’élèves sont venus dans les salles de travaux pratiques de la plateforme électronique de l’Université de Rennes 1 pendant deux demi-journées afin de dimensionner, simuler, réaliser et mesurer une antenne Yagi pour des applications WiFi

Initiation à la conception d’antennes Yagi-Uda pour des lycéens

Dans le cadre des actions de sensibilisation vers l’enseignement secondaire du projet ANR FINMINA [2], une initiation à la conception d’antennes est proposée aux lycées de l’Académie de Rennes. Dans ce cadre, depuis 2016, plusieurs groupes d’élèves sont venus dans les salles de travaux pratiques de la plateforme électronique de l’Université de Rennes 1 pendant deux demi-journées afin de dimensionner, simuler, réaliser et mesurer une antenne Yagi pour des applications WiFi

Comparison between a 3D UTD model and near field chamber measurements in the presence of a dielectric circular cylinder

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C-Band 2×2 MIMO multi-carrier tomographic radar for complex environment volumetric imaging

International audienceIn this paper, we present a C-Band 2 ×2 MIMO Multi-Carrier Radar system that has been realised at the IETR laboratory and a new modulation technique that permits to avoid the use of switches. To validate this system, measurements have been done with two trihedral corner reflectors lying on a grass field, using our system and a VNA. We have processed the acquired data using the Back Projection Algorithm (BPA). VNA and MIMO-MCR give similar results with a vertical resolution of 0.37 [email protected] m ground range and a vertical ambiguity of 0.74 [email protected] m ground range. Therefore, the system is fully operational. © 2018 IEEE

ESTIMATION OF DIRECTION OF ARRIVAL (DOA) OF DVB-T SIGNALS IN MOBILE RECEIVING CONFIGURATION

To improve the quality of the mobile reception of DVB-T (Digital Video Broadcasting on Terrestrial networks) signal, the knowledge of the propagation channel characteristics is necessary. In this aim, this paper presents sounding methods and results for the estimation of Direction of Arrival (DoA) of DVB-T signals in mobile receiving configuration. The mobile passive sounder is presented, including postprocessing and radio direction finding tools. Then several results in three kinds of environment are given. 1