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In this work, we present a complete multiphysics modelling (via the Finite Element Method, FEM) of an air coupled piezoelectric micromachined ultrasonic transducer (PMUT) with preliminary experimental validations. The PMUT is a suspended layered membrane, in which one of the layers is made of piezoelectric material. By means of an applied voltage over the piezoelectric layer thickness, the device emits acoustic waves in air. The model takes into account the multiple interactions between electrical, mechanical and acoustic fields, and in particular gives a realistic estimation of the device quality factor by means of a proper modelling of thermo-viscous losses in the fluid domain. The complexity of the model is increased by the presence of initial large deformations in the membrane and fabrication induced residual stresses. Preliminary experimental matchings are presented for static pre-deflection of the membrane due to residual stresses and for the eigenfrequency corresponding to acoustic wave emission.

In this paper a complete Multiphysics modelling via the Finite Element Method (FEM) of an air-coupled Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is described, with its experimental validation related to the mechanical and acoustic responses.

Towards the fabrication of all-dielectric nanophotonic devices with tunable capabilities, we combined interband and intraband nonlinearities in aluminum-doped zinc oxide thin films thus enlarging the material bandwidth and gaining ultra-fast control over the transmitted spectrum.

A set of rotational test structures for on-chip fracture characterization of 0.7 /spl mu/m thick polysilicon film have been designed, modeled and fabricated. The structures are actuated by a large number of comb-fingers capacitors which develop a force sufficient to load the specimens in bending up to rupture. A 3D FE model of the whole structures was used during the design phase. Tests were carried out at room temperature and at atmospheric humidity. The measured Young modulus of the tested polysilicon was 182/spl plusmn/9 GPa. The low dispersion around the mean value confirms the quality and the good reliability of the whole procedure. Rupture stresses computed after the application of Weibull theory were 1875/spl plusmn/333 MPa.

A new MEMS for on-chip mechanical testing of 0.9 /spl mu/m thick polysilicon film has been designed, modelled and fabricated. The polysilicon film is electrostatically loaded under bending until rupture in the out of plane direction, by means of electrostatic attraction in the direction orthogonal to the substrate. This is at difference with previous works of the same authors, in which results relevant to in plane loading conditions have been presented. 3D finite element (FE) and boundary element (BE) models of the structure were used during the design and data reduction phases. Tests were carried out at room temperature and at atmospheric humidity. The measured Young modulus of the tested polysilicon was 169 /spl plusmn/ 11 GPa. Rupture stress computed after the application of Weibull theory was 5669 MPa, with a Weibull modulus m = 22.5.

A set of rotational test structures for on-chip fracture characterization of 0.7 ,urn thick polysilicon film have been designed, modeled and fabricated. The structures are actuated by a large number of comb-fingers capacitors which develop a force sufficient to load the specimens in bending up to rupture. A 3D FE model of the whole structures was used during the design phase. Tests were carried out at room temperature and at atmospheric humidity. The measured Young modulus of the tested polysilicon was 182 & 9 GPa. The low dispersion around the mean value confirms the quality and the good reliability of the whole procedure. Rupture stresses computed after the application of Weibull theory were 1875 f 333 MPa.