10 research outputs found
Fabrication and characterization of composite MEMS for mechanical energy harvesting
Les rĂ©cents progrĂšs dans le domaine des MEMS organiques suscitent un intĂ©rĂȘt croissant dans la substitution de micropoutres inorganiques par des micropoutres organiques pour diverses applications. Nâayant Ă©tĂ© Ă©tudiĂ©e quâen mode statique, la rĂ©ponse Ă©lectrostrictive des MEMS organiques est prĂ©sentĂ©e pour la premiĂšre fois en mode dynamique. Lâune des originalitĂ©s de ce travail est de fabriquer un micro-rĂ©cupĂ©rateur dâĂ©nergie mĂ©canique avec une approche « tout-organique ». Dans cette thĂšse, des matĂ©riaux nanocomposites Ă base dâoxyde de graphĂšne rĂ©duit (rGO) dispersĂ© dans du poly-dimethyl siloxane (PDMS), sont utilisĂ©s pour la rĂ©cupĂ©ration de l'Ă©nergie mĂ©canique vibratoire avec une transduction Ă©lectrostrictive. Le dispositif gĂ©nĂšre une densitĂ© de puissance Ă©lectrique de 8,15 W/cm3 pour une accĂ©lĂ©ration de 1 g au premier mode de rĂ©sonance (â 17 Hz).Recent advances in the field of organic MEMS have generated interest in the substitution of inorganic microbeams by organic ones for various applications. Until now, the use of electrostrictive materials is limited to the MEMS operating mostly in static mode. The electrostrictive response of organic MEMS is presented here for the first time in dynamic mode. One of the originality of this work is to produce a micro-mechanical energy harvester fabricated in an all-organic approach. In this thesis, strain sensitive nanocomposite materials based on reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) are used for mechanical vibratory energy harvesting with an electrostrictive transducer. With an acceleration of 1 g of the microcantilever base, actuation at the first resonant mode (â 17 Hz) generates an electrical power density of 8.15 ÎŒW/cm3
Fabrication et caractérisation des MEMS composite pour la récupération d'énergie mécanique
Recent advances in the field of organic MEMS have generated interest in the substitution of inorganic microbeams by organic ones for various applications. Until now, the use of electrostrictive materials is limited to the MEMS operating mostly in static mode. The electrostrictive response of organic MEMS is presented here for the first time in dynamic mode. One of the originality of this work is to produce a micro-mechanical energy harvester fabricated in an all-organic approach. In this thesis, strain sensitive nanocomposite materials based on reduced graphene oxide (rGO) dispersed in polydimethylsiloxane (PDMS) are used for mechanical vibratory energy harvesting with an electrostrictive transducer. With an acceleration of 1 g of the microcantilever base, actuation at the first resonant mode (â 17 Hz) generates an electrical power density of 8.15 ÎŒW/cm3.Les rĂ©cents progrĂšs dans le domaine des MEMS organiques suscitent un intĂ©rĂȘt croissant dans la substitution de micropoutres inorganiques par des micropoutres organiques pour diverses applications. Nâayant Ă©tĂ© Ă©tudiĂ©e quâen mode statique, la rĂ©ponse Ă©lectrostrictive des MEMS organiques est prĂ©sentĂ©e pour la premiĂšre fois en mode dynamique. Lâune des originalitĂ©s de ce travail est de fabriquer un micro-rĂ©cupĂ©rateur dâĂ©nergie mĂ©canique avec une approche « tout-organique ». Dans cette thĂšse, des matĂ©riaux nanocomposites Ă base dâoxyde de graphĂšne rĂ©duit (rGO) dispersĂ© dans du poly-dimethyl siloxane (PDMS), sont utilisĂ©s pour la rĂ©cupĂ©ration de l'Ă©nergie mĂ©canique vibratoire avec une transduction Ă©lectrostrictive. Le dispositif gĂ©nĂšre une densitĂ© de puissance Ă©lectrique de 8,15 W/cm3 pour une accĂ©lĂ©ration de 1 g au premier mode de rĂ©sonance (â 17 Hz)
HighâSensitivity RFID Sensor for Structural Health Monitoring
Abstract Structural health monitoring (SHM) is crucial for ensuring operational safety in applications like pipelines, tanks, aircraft, ships, and vehicles. Traditional embedded sensors have limitations due to expense and potential structural damage. A novel technology using radio frequency identification devices (RFID) offers wireless transmission of highly sensitive strain measurement data. The system features a thin, flexible sensor based on an inductanceâcapacitance (LC) circuit with a parallelâplate capacitance sensing unit. By incorporating tailored cracks in the capacitor electrodes, the sensorâs capacitor electrodes become highly piezoresistive, modifying electromagnetic wave penetration. This unconventional change in capacitance shifts the resonance frequency, resulting in a wireless strain sensor with a gauge factor of 50 for strains under 1%. The frequency shift is passively detected through an external readout system using simple frequency sweeping. This wireâfree, powerâfree design allows easy integration into composites without compromising structural integrity. Experimental results demonstrate the cracked wireless strain sensor's ability to detect small strains within composites. This technology offers a costâeffective, nonâdestructive solution for accurate structural health monitoring
Design Strategies for StrainâInsensitive Wearable Healthcare Sensors and Perspective Based on the Seebeck Coefficient
Abstract Large healthcare markets have been created in highly developed economies to improve the quality of life. Wearable healthcare sensors are attracting considerable interest because of their 24 h realâtime monitoring capability, which make them useful in the detection of potential diseases. To guide the diagnosis, these sensors are designed to monitor various physical (e.g., pressure, temperature, strain, touch, bioelectricity, etc...) or chemical (e.g., glucose, oxygen, bacteria, viruses, proteins, etc...) quantities. In order to be comfortable to wear for a longer period of time, the sensors must be made with good stretchability to conformably deform with human organs. However, high stretchability always brings the problem that the measurement is very often polluted by the deformation of the substrate, making the data unreliable. According to each the sensor mechanism, multiple strainâinsensitive design strategies compatible with large deformations of the human body are discussed and the performance of these strategies are comprehensively analyzed. Then, how the intrinsic strain insensitivity of the Seebeck coefficient of nanomaterial percolation networks can define an alternative promising strategy is demostrated. Finally, the outlooks for future research and challenges in realizing strainâinsensitive sensors by applying the Seebeck effect are reported
Electrostrictive MEMS dedicated to mechanical energy harvesting: fabrication and characterization
International audienc
Electrostriction as an integrated transduction method for organic MEMS
International audienc
Organic microcantilevers based on reduced graphene oxide composite for electrostrictive energy harvesting
International audienc