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International audience; Bluetooth Low Energy (BLE) is a promising 2.4 GHz technology for Body Area Networks (BAN) in health care and lifestyle applications. However, the global increase of wireless devices using the crowded spectrum in the 2.4 GHz frequency band can create coexistence issues. This work studies the performance of BLE in environments with multiple BLE devices. An experimental setup consisting of 10 BLE nodes is used to measure BLE application throughput with different connection parameters and under different interference sources, such as other BLE devices and WiFi. The results quantify the decrease of the application throughput and the influence of BLE connection parameters in the experimental settings, as well as suggest parameter values suitable for densely deployed environments.

International audience; The paper discusses the outcomes of the conference organized by the InDeal project. The conference took place on 12 December 2018 in Montpellier as part of the EnerGaia energy forum 2018. A holistic interdisciplinary approach for district heating and cooling (DHC) networks is presented that integrates heterogeneous innovative technologies from various scientific sectors. The solution is based on a multi-layer control and modelling framework that has been designed to minimize the total plant production costs and optimize heating/cooling distribution. Artificial intelligence tools are employed to model uncertainties associated with weather and energy demand forecasts, as well as quantify the energy storage capacity. Smart metering devices are utilized to collect information about all the crucial heat substations parameters, whereas a web-based platform offers a unique user environment for network operators. Three new technologies have been further developed to improve the efficiency of pipe design of DHC systems: (i) A new sustainable insulation material for reducing heat losses, (ii) a new quick-fit joint for an easy installation, and (iii) a new coating for reducing pressure head losses. The results of a study on the development and optimization of two energy harvesting systems are also provided. The assessment of the environmental, economic and social impact of the proposed holistic approach is performed through a life cycle analysis. The validation methodology of the integrated solution is also described, whereas conclusions and future work are finally given.

International audience; This paper reports the fabrication of arrays of vertical piezoelectric nanowires which are individually contacted at their base, and demonstrates that an electrical response to strain can be obtained from individual nanowires from the array, without external biasing exploiting the piezotronic effect. Such a technology could thus be used for the fabrication of self-powered sensors for mechanical strain mapping, where each individually contacted nanowire would act as the strain sensing equivalent of a pixel. Lateral mapping resolutions in the micrometer range can be obtained. Here, the hydrothermal method was used to grow vertical ZnO nanowires selectively between two electrodes that had been patterned beforehand. For the sake of demonstration, nanowires deflection was produced by subjecting the array of nanowires to an incident lateral gas flow of controlled rate, which was switched on and off repeatedly across the sample while electrical response was measured. Different experimental configurations were tested in terms of flow rate, flow orientation, or nanowire position with respect to tube outlet. Experiments were carried out with compressed nitrogen and air. The experimental results are fully consistent with the piezoelectric and piezotronic response which can be expected with this geometry. Moreover, it is shown that the electrical response under nitrogen flow is a linear function of flow rate and that its sign provides information about flow direction. These results demonstrate the very promising prospects of this new technology for high-resolution mapping, with potential applications in gas or liquid flow sensing, fingerprints detection or human-machine interfaces.

International audience; The evolutions of medicine covering genome to exposome (i.e. all types of environmental exposures) [1] opened new paths of development for electronics including low power sensors. Additionally, the frontiers for new generations of sensors between smart-living, environment and health are fading. In this paper, we will give examples based on our developments in emerging autonomous sensors and medical devices, and show how they can be included in our daily life

The work presented here describes new UV-crosslinkable thin layer polymeric materials for the encapsulation of ZnO nanowires (NWs) in multi-NWs pressure based fingerprint sensors. Such innovative sensor is a novel technology for fingerprint capture developed within the PiezoMAT FP7 European project. The sensing principle is based on the piezoelectric property of ZnO NWs, on which a potential difference is generated when they undergo compression and/or bending forces. Since the pressure induced by the finger cannot be directly applied on the NWs, the deformation is applied through a polymeric material that aims at transferring forces from the finger onto the array of NWs without altering their integrity. Besides, since it is dedicated to be in direct contact with human finger or oil pollutants, the encapsulation layer must also exhibit chemical inertness, as well as hydrophobicity and oleophobicity.

This paper reports the optimization and the characterization of a 4 cm diameter water flow energy harvester inserted in pipes. In this work, a test-bench has been implemented to measure the harvester’s electrical output powers, rotation frequencies and pressure losses. Furthermore, long-term tests have been carried out in a district heating and cooling system (DHCS) in order to validate its operation in a real environment. Output powers up to 490mW @ 9 m3.h−1 are reported with a mean output power of 5mW in real conditions (Montpellier’s DHCS in France). The pressure losses induced by the turbine and the energy extraction remains lower than 50 mbars which is among the lowest in the state of the art.

An all solid-state-microbattery is defined as a stack of thin layers (5-20µm) including the active part, protective layers and current collectors. [1] In this work, the stack Li/LiPON/TiOS is studied. Titanium oxysulfide thin films (TiOySz) are used as positive electrode material. This material was selected because of their specific potential (reversibly insert of lithium below 3V vs. Li+/Li) well adapted for the considered application. Capacity of 100µA.h/cm2/µm can be reached. Correlation between microstructure, chemistry and performance of the active material is reported.

SOFC technology is assumed to have significant potential in energy conversion although many obstacles still prevent its widespread use. Among these, the cost of scaling up existing manufacturing processes for mass production is of major concern. With thermal spray technology, SOFCs can be produced without implementing time consuming sintering steps required in wet ceramic processing. Suspensions Plasma Spraying is one of the promising solutions because it produces thin layer with finer and more adapted microstructures. In the present work, water or alcoholic suspensions of sub-micronic, YSZ/NiO for hydrogen electrode and La2NiO4 for oxygen electrode have been studied to achieve a good dispersion and stability. These optimised suspensions have been injected into the plasma spray system to produce porous coatings of 40 µm thick onto ferritic porous substrates. The evolution of the morphology and crystalline structure of the electrodes have been investigated by SEM/EDS and XRD with the operating parameters.

The continuous contamination of the cathode with chromium released from metallic interconnects speeds up the degradation of the performance of the cell. For this reason Solid Oxide Fuel Cell (SOFC) interconnects are coated with a dense protective layer. This layer plays the role of a diffusion barrier for the chromium evaporation at operating conditions. The deposition of a dense, gas tight and stable MnCo2O4 spinel layer on ferritic alloy using the atmospheric plasma spraying (APS) process is studied. The first experimental results show that the plasma spray process combined with an appropriate post thermal-treatment is suitable to form a dense spinel protective layer.

This paper reports on the performances and the optimization of a 40 mm diameter water flow energy harvester based on an axial turbine (horizontal axis propeller) coupled to a customized permanent magnet generator. To the best of our knowledge, this work is one of the first comprehensive studies in the low dimensional and flow velocities ranges. The parameters of the propeller have been empirically optimized (\(\lambda_D\)=1, B=4 blades) by the means of experiments in a test-bench pipe at various flow rates from 1 to 9 m3 h−1. The best propeller design has been selected for its performances in terms of electrical power and pressure drop. A customized permanent magnet converter with ferromagnetic elements has been modeled, optimized with finite elements simulations and fabricated. This has enabled to increase the electrical power by 2.7 @ 1.5 m3 h−1 (3.2 mW) and up to 14.1 @ 9 m3 h−1 (490 mW) compared to a simple magnet-air coil converter. The figure of merit of our water flow harvester, which takes the electrical power and the pressure drops in the pipe into account, is greater than previously reported water flow energy harvesters, and corresponds to an overall mechanical-to-electrical conversion efficiency of 5.15%.