Fabrication and characterization of composite MEMS for mechanical energy harvesting

Les récents progrès dans le domaine des MEMS organiques suscitent un intérêt croissant dans la substitution de micropoutres inorganiques par des micropoutres organiques pour diverses applications. N’ayant été étudiée qu’en mode statique, la réponse électrostrictive des MEMS organiques est présentée pour la première fois en mode dynamique. L’une des originalités de ce travail est de fabriquer un micro-récupérateur d’énergie mécanique avec une approche « tout-organique ». Dans cette thèse, des matériaux nanocomposites à base d’oxyde de graphène réduit (rGO) dispersé dans du poly-dimethyl siloxane (PDMS), sont utilisés pour la récupération de l'énergie mécanique vibratoire avec une transduction électrostrictive. Le dispositif génère une densité de puissance électrique de 8,15 W/cm3 pour une accélération de 1 g au premier mode de résonance (≈ 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 (≈ 17 Hz) generates an electrical power density of 8.15 μW/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 (≈ 17 Hz) generates an electrical power density of 8.15 μW/cm3.Les récents progrès dans le domaine des MEMS organiques suscitent un intérêt croissant dans la substitution de micropoutres inorganiques par des micropoutres organiques pour diverses applications. N’ayant été étudiée qu’en mode statique, la réponse électrostrictive des MEMS organiques est présentée pour la première fois en mode dynamique. L’une des originalités de ce travail est de fabriquer un micro-récupérateur d’énergie mécanique avec une approche « tout-organique ». Dans cette thèse, des matériaux nanocomposites à base d’oxyde de graphène réduit (rGO) dispersé dans du poly-dimethyl siloxane (PDMS), sont utilisés pour la récupération de l'énergie mécanique vibratoire avec une transduction électrostrictive. Le dispositif génère une densité de puissance électrique de 8,15 W/cm3 pour une accélération de 1 g au premier mode de résonance (≈ 17 Hz)

High‐Sensitivity 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 inductance‐capacitance (LC) circuit with a parallel‐plate capacitance sensing unit. By incorporating tailored cracks in the capacitor electrodes, the sensor’s 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 wire‐free, power‐free 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 cost‐effective, non‐destructive solution for accurate structural health monitoring

Design Strategies for Strain‐Insensitive 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 real‐time 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 strain‐insensitive 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 strain‐insensitive sensors by applying the Seebeck effect are reported

MEMS Resonators Activities at the IMS

National audienc

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