Design et développement d'un capteur acoustique imprimé.

The objective of this work was to design and fabricate a low cost resonant capacitive acoustic sensor using printing techniques. It falls within the frame of a collaborative research project named “Spinnaker”, set up by TAGSYS RFID, a French company, which has planned to integrate this sensor to improve the geolocalization of their RFID tags. This work started with the design and optimization of the sensor using finite element modeling (COMSOL) and design of experiments (DOE). This first step has enabled the identification of the optimum set of parameters and demonstrated that the output responses were in accordance with the specifications. Then, we have developed the different technological building blocks required for the fabrication of the prototypes using jointly the 2D inkjet printing technique and 3D printing method. The functionality of the sensors has been characterized using both capacitive and acoustic measurements using laser Doppler vibrometer. Experimental results showed that sensitivity and selectivity were within the specifications and in good agreement with the modeling results. Finally, we investigated the piezoelectric approach which could be an interesting option to the capacitive one. Since no inkjet printable piezoelectric ink is commercially available, stable inkjet printable polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) ink has been developed. PVDF-TrFE layers were then successfully printed and characterized. The results were quite promising, however further improvements of the ink and printing process are required before stepping towards piezoelectric based device fabrication.L’objectif de ce travail était de concevoir et réaliser par impression un capteur acoustique capacitif résonant bas coût. Il s’inscrit dans le cadre d’un projet collaboratif de recherche intitulé « Spinnaker », défini par la société Tagsys RFID qui souhaite intégrer ce capteur afin d’améliorer la géolocalisation des étiquettes RFID. Ce travail a débuté par la conception et l’optimisation du design en utilisant la simulation par éléments finis (COMSOL) ainsi que des plans d’expériences (DOE : Design of Experiment). Cette première étape a permis de déterminer les paramètres optimaux et démontrer que les performances obtenues étaient conformes aux spécifications. Nous avons ensuite développé les différentes briques technologiques nécessaires à la réalisation des prototypes en utilisant conjointement l’impression 2D par inkjet et l’impression 3D. Nous avons vérifié la fonctionnalité de ces capteurs à l’aide de mesures électriques capacitives et acoustiques par vibrométrie laser. Nous avons démontré la sélectivité en fréquence des capteurs réalisés et comparé les résultats expérimentaux à ceux obtenus par simulation. Enfin, nous avons enfin exploré la « voie piezoélectrique » qui nous semble être une alternative intéressante au principe capacitif. En l’absence d’encre piézoélectrique commerciale imprimable par jet de matière, nous avons formulé une encre imprimable à base du co-polymère PVDF-TrFE et démontré le caractère piézoélectrique des couches imprimées. Les résultats sont prometteurs mais des améliorations doivent encore être apportées à cette encre et au procédé d’impression avant de pouvoir fabriquer des premiers prototypes

Fabrication of Capacitive Acoustic Resonators Combining 3D Printing and 2D Inkjet Printing Techniques

International audienceA capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency

Design and development of printed acoustic sensor

L’objectif de ce travail était de concevoir et réaliser par impression un capteur acoustique capacitif résonant bas coût. Il s’inscrit dans le cadre d’un projet collaboratif de recherche intitulé « Spinnaker », défini par la société Tagsys RFID qui souhaite intégrer ce capteur afin d’améliorer la géolocalisation des étiquettes RFID. Ce travail a débuté par la conception et l’optimisation du design en utilisant la simulation par éléments finis (COMSOL) ainsi que des plans d’expériences (DOE : Design of Experiment). Cette première étape a permis de déterminer les paramètres optimaux et démontrer que les performances obtenues étaient conformes aux spécifications. Nous avons ensuite développé les différentes briques technologiques nécessaires à la réalisation des prototypes en utilisant conjointement l’impression 2D par inkjet et l’impression 3D. Nous avons vérifié la fonctionnalité de ces capteurs à l’aide de mesures électriques capacitives et acoustiques par vibrométrie laser. Nous avons démontré la sélectivité en fréquence des capteurs réalisés et comparé les résultats expérimentaux à ceux obtenus par simulation. Enfin, nous avons enfin exploré la « voie piezoélectrique » qui nous semble être une alternative intéressante au principe capacitif. En l’absence d’encre piézoélectrique commerciale imprimable par jet de matière, nous avons formulé une encre imprimable à base du co-polymère PVDF-TrFE et démontré le caractère piézoélectrique des couches imprimées. Les résultats sont prometteurs mais des améliorations doivent encore être apportées à cette encre et au procédé d’impression avant de pouvoir fabriquer des premiers prototypes.The objective of this work was to design and fabricate a low cost resonant capacitive acoustic sensor using printing techniques. It falls within the frame of a collaborative research project named “Spinnaker”, set up by TAGSYS RFID, a French company, which has planned to integrate this sensor to improve the geolocalization of their RFID tags. This work started with the design and optimization of the sensor using finite element modeling (COMSOL) and design of experiments (DOE). This first step has enabled the identification of the optimum set of parameters and demonstrated that the output responses were in accordance with the specifications. Then, we have developed the different technological building blocks required for the fabrication of the prototypes using jointly the 2D inkjet printing technique and 3D printing method. The functionality of the sensors has been characterized using both capacitive and acoustic measurements using laser Doppler vibrometer. Experimental results showed that sensitivity and selectivity were within the specifications and in good agreement with the modeling results. Finally, we investigated the piezoelectric approach which could be an interesting option to the capacitive one. Since no inkjet printable piezoelectric ink is commercially available, stable inkjet printable polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) ink has been developed. PVDF-TrFE layers were then successfully printed and characterized. The results were quite promising, however further improvements of the ink and printing process are required before stepping towards piezoelectric based device fabrication

Triboelectric effect to harness fluid flow energy

We are reporting energy scavenging from fluid flows inside tubular structures using triboelectric effects. Two separate designs of triboelectric generators are proposed. A tubular design that uses liquid-solid interaction mechanism for water, and freestanding flapping films design utilizing contact-separation mechanism for wind flow energies conversions. The developed generators exhibit capabilities to produces power from fluid motions through the tube. Osmotic water having conductivity of 2.05 +/- 0.05 mu S/cm provides higher triboelectric responses in comparison to tap water (conductivity of 322.0 +/- 2.0 mu S/cm) flow. An average power of 37.4 mu W for an osmotic water flow of 82.5 +/- 0.5 cm(3)/s was generated for two pairs of triboelectric generators. Under a wind flow of 8.2 +/- 0.1 m/s and using three pairs of generators an average power of 144.8 mu W was obtained across an optimum load resistance (R-L) of 7.6 M Omega

Crystallization and mechanical properties of functionalized single-walled carbon nanotubes/polyvinylidene fluoride composites

Single-walled carbon nanotubes were purified and functionalized by nitric acid and octadecylamine. Raman and Fourier transform infrared spectroscopy were used to characterize the functionalization of the single-walled carbon nanotubes. Polyvinylidene flouride nanocomposites containing 1 wt% purified or functionalized single-walled carbon nanotubes were prepared by solution blending and injection molding. The dispersion of different carbon nanotubes in dimethylformamide and in polyvinylidene flouride has been investigated. Mechanical properties show that adding single-walled carbon nanotubes could improve the tensile properties when the dispersion is good. </jats:p

Soft Triboelectric Band for Sensing of and Energy Scavenging From Body Motion

We manifest a new method of developing wearable triboelectric band for self-powerd gesture sensing and power generating. Film casting technique, that is easily scalable, was used to patterned soft stretchable elastomers and conductive carbon based composites. The developed triboelectric band showed the capabilities of detecting locomotion of elbow and knee movement and provides electrical signal in response. The rms voltage, current and power of 2.9 V, 0.3 μA and 1.6 μW for elbow stretching, and 1.1 V, 0.11 μA and 0.22 μW for knee stretching was obtained for the optimum load of 10.1 MΩ at operational frequency of 1 ± 0.1 Hz

Fabrication of Capacitive Acoustic Resonators Combining 3D Printing and 2D Inkjet Printing Techniques

A capacitive acoustic resonator developed by combining three-dimensional (3D) printing and two-dimensional (2D) printed electronics technique is described. During this work, a patterned bottom structure with rigid backplate and cavity is fabricated directly by a 3D printing method, and then a direct write inkjet printing technique has been employed to print a silver conductive layer. A novel approach has been used to fabricate a diaphragm for the acoustic sensor as well, where the conductive layer is inkjet-printed on a pre-stressed thin organic film. After assembly, the resulting structure contains an electrically conductive diaphragm positioned at a distance from a fixed bottom electrode separated by a spacer. Measurements confirm that the transducer acts as capacitor. The deflection of the diaphragm in response to the incident acoustic single was observed by a laser Doppler vibrometer and the corresponding change of capacitance has been calculated, which is then compared with the numerical result. Observation confirms that the device performs as a resonator and provides adequate sensitivity and selectivity at its resonance frequency