Chipless tag printed with common off the shelf inkjet printer and air dry conductive ink

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Actionnement et récupération d'énergie à l'aide de polymères électro-actifs

Grâce aux avancées technologiques actuelles, les matériaux conventionnels tels que les métaux, aciers, sont remplacés par les polymères, dans la plupart des secteurs d'activité comme l'automobile, l'aéronautique. En effet les niveaux de connaissance et de savoir faire technologique permettent maintenant de fabriquer des polymères avec les propriétés mécanique et électrique désirées. Rendant ainsi possible la conception de système à des coûts moindres, avec des encombrements et des masses plus faibles. De plus les polymères ont des propriétés intéressantes par rapport aux matériaux inorganiques (type céramique ou mono-cristaux). Ils sont légers, peu coûteux, pliables; ils peuvent être configurés dans des formes complexes et leurs propriétés peuvent être adaptées en fonction de la demande. Grâce à l évolution conjuguée des sciences et des technologies, un certain niveau d'intelligence >> peut être insufflé à ceux-ci au niveau moléculaire. Ces matériaux intelligents peuvent sentir les variations de l'environnement, et réagir en conséquence, tel que les matériaux à alliages de mémoire de forme ou piézo-électriques ... et plus communément appelés polymères électro-actifs. L'une des applications possible de ces polymères se trouve à la croisée des technologies de bio-mimétisme et d'énergie renouvelable. Diverses machines imitant les oiseaux, les poissons, ont été développées. Les technologies dites vertes sont devenues incontournables dans le paysage économique contemporain. C'est autour de ces problématiques que le travail de recherche a été organisé. Les objectifs des travaux présentés dans ce manuscrit sont triples. Le premier consiste en la caractérisation électriquement et mécaniquement des polymères et composites, réalisés au laboratoire à partir de matrice de polyuréthane et de P (VDF-TrFE-CFE). Les deux autres concernent l'étude des composites polymères électrostrictifs fabriqués au laboratoire sur le plan de l'actionnement et de la récupératio11 d'énergie.Polymers have attractive properties compared to inorganic materials. They are lightweight, inexpensive, fracture tolerant, pliable, and easily processed and manufactured. They can be configured into complex shapes and U1eir properties can be tailored according to demand. With the rapid advances in materials used in science and tecl1nology, various materials with Intelligence embedded at the molecular level are being developed at a fast pace. These smart materials can sense variations in the environment, process the information, and respond accordingly. Shape-memory alloys, piezoelectric materials, etc. fall in tt1is category of intelligent materials. Polymers that respond to external stimuli by changing shape or size have been known and studied for several decades. They respond to stimuli such as an electrical field, pH, a magnetic field, and light. These intelligent polymers can collectively be called active polymers. One of the significant applications of these active polymers is found in biomimetics-the practice of taking ideas and concepts from nature and implementing them in engineering and design. Various machines that imitate birds, fish, insects and even plants have been developed. With the increased emphasis on "green" technological solutions to contemporary problems, scientists started exploring the ultimate resource-nature-for solutions that have become highly optimized du ring the millions of years of evolution. The objectives of the work reported in the present document are threefold. The first aim consists in electrical and mechanical characterization of polymer and composites, realized in the laboratory with matrix of polyurethane and P(VDF-TrFE-CFE). The others two parts concerns the study of a new electrostrictive polymer composite (EPC) to be used in actuators and mechanical energy harvesters.VILLEURBANNE-DOC'INSA LYON (692662301) / SudocSudocFranceF

Induction heating properties of ferromagnetic composite for varicose veins healing

International audienceIn this study, we investigate ferromagnetic composites made of ABS thermoplastic matrix fulfilled with iron oxide particles (Fe3O4). The low frequency induction heating effect (LFIH) in such composites is mainly due to the hysteresis losses linked to the magnetic domain's wall motions under low frequency alternating magnetic excitation fields [1][2][3]. Therefore, LFIH can be used as varicose veins treatment. In the future, the LFIH method will probably outclass the existing treatment methods as its performances in terms of precision, cost and applicability seem much better [4]. For the hysteresis characterization of the magnetic properties and validation of the LFIH method, samples with different shapes and particle volume fractions were built. Magnetic properties such as hysteresis cycles, permeability, remnant inductions, and coercive fields … were measured using the experimental test bench illustrated in Fig. 1. For the validation of the LFIH method, a specific experimental test-bench was developed. This new setup is shown in Fig. 2. An alternative magnetic field with significant amplitude under a frequency range varying from a few hundred Hz to 2.5 KHz was generated by an inductor made of 8 strong permanent magnets located on a high speed electric motor rotating output shaft. A significant temperature increase of the ferromagnetic composite was observed by the thermal camera after 5 minutes, as illustrated in Fig. 3 a). To highlight the ferromagnetic composites induction heating effect, a comparison with electrically conductive but non-ferromagnetic samples was performed. In Fig. 3 b), as opposed to the ferromagnetic composite, the conductive sample exhibited a very weak response to the magnetic field excitation and no temperature variation was observed. The temperature variations of the ferromagnetic composites confirmed their potential as local heating and healing treatment for medical applications. Characterizations under simultaneous magnetic and thermic excitation also revealed very stable magnetic properties (stable permeability can been achieved on a very large temperature range) confirming the reliability of the developed composite magnetic properties. Figure 1. Experimental setup for the magnetic characterization of the magnetic composites

Modeling and experimentation of an electrostrictive polymer composite for energy harvesting

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Electrostrictive polymer composite for energy harvesters and actuators

International audiencePolymers have attractive properties when compared with inorganic materials: they are lightweight, inexpensive, pliable, and easily processed and manufactured. They can be configured into complex shapes and their properties can be tailored according to demand. With the rapid advances in materials used in science and technology, various substances embedded with intelligence at the molecular level are being developed. A type of electroactive polymer known as electrostrictive has shown considerable promise for a variety of applications, such as actuation with a strain thickness of 15% for an electric field of 10 V/μm. Polyurethane-based nanocomposite films were prepared by incorporating a carbon black nanopowder (C) into the polymer matrix. Electric field-induced strain measurements revealed that a loading of 1 vt% C (volume percentage of carbon black nanopowder) increased the strain level by a factor of 2.5 at a moderate field strength (10 V/μm). Moreover, another application for this material concerned the harvesting of mechanical energy, which constitutes an attractive alternative to the strict reliance on traditional batteries with limited lifetimes. For instance, an effective conversion from the mechanical-to-electric domains of 2.3 μW/cm3, under a transverse vibration level of 0.25% at 100 Hz, has been demonstrated for nylon. The final results indicated that the dielectric constant was a crucial parameter for energy harvesting

Accurate Electroadhesion Force Measurements of Electrostrictive Polymers: The Case of High Performance Plasticized Terpolymers

Electroadhesion is a phenomenon ruled by many characteristic intrinsic parameters. To achieve a good adhesion, efficient and durable, a particular attention must be provided to the adhesion forces between the involved parts. In addition to the size and geometry of electrodes, parameters of materials such as dielectric constant, breakdown electric field, and Young’s modulus are key factors in the evaluation of electroadhesion efficiency for electrostrictive polymers and electroactive devices. By analyzing these material parameters, a method is proposed to justify the choice of polymer matrices that are fit to specific electroadhesion applications. Another purpose of this work aims to demonstrate a possibility of accurately measuring the electroadhesion force. This physical parameter has been usually estimated through equations instead, because of the complexity in setup implementation to achieve highly precise measure. Comparisons based on the parameters criterion reveal that besides the intrinsic properties of material, some other parameters relating to its physical phenomena (e.g., saturation of dipolar orientation under high electric field leads to decrease dielectric constant), or physical behavior of the system (i.e., surface roughness reduces the active electrode area) must be thoroughly considered. Experimental results pointed out that plasticized terpolymer leads boosted electroadhesion performance compared to the other counterparts, up to 100 times higher than conventional polymers. The developed materials show high potential in applications of active displacement control for electrostrictive actuation