Onuma SANTAWITEE soutiendra sa thèse, jeudi 24 septembre à 10h30, dans l'Amphi J-P.DOM du Laboratoire IMS, sur le sujet suivant "Etude de composants piézoélectriques à base de couches épaisses imprimées et libérées . Application à la détection de COVs à l'aide de micropoutres avec couche sesnible de silice mésoporeuse"

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Title: Study of piezoelectric devices based on free-standing printed thick-films. Application to VOCs detection using micro-cantilevers with mesoporous silica sensitive coating

English summary:
Screen-printing associated with the sacrificial layer technique is a low cost process allowing preparation of piezoelectric thick films microsystems. However, material choices and process conditions could affect microstructure and consequently electromechanical properties of printed thick films. In this work, high densified PZT (PbZrTiO3) disks have been firstly fabricated from a screen-printing paste containing nano-metric PZT powder and sintering aid. These disks, printed on a polyester sacrificial layer showed properties approaching those of commercial samples. In the second part of this work, the optimized paste has been used for processing of a micro-cantilever used for Volatile Organic Compounds (VOCs) sensing. The detection is based on the resonant frequency shift of the vibrating micro-cantilever. By drop casting of a high surface area meso-cellular foam silica onto cantilever in size of 3x2x0.1 mm3, a sensitivity of ≈0.24 Hz/ppm under toluene vapor has been obtained at room temperature due to gas sorption in the mesoporous silica. With these performances, this sensor would be benefit to environmental monitoring field.

Keywords: [volatile organic compounds, screen-printing, mesoporous silica, piezoelectric materials, micro-cantilever, sacrificial layer]