Marco De Fazio

Optical Detection of the Electromechanical Response of MEMS Micromirrors Designed for Scanning Picoprojectors

Single-axis rotational micromirrors actuated by comb finger structures have been designed in view of their application in reflective scanning picoprojectors for laser beam displacement along two perpendicular directions to obtain a raster scan scheme. A resonant mirror operating at a frequency around 25 kHz, suitable for horizontal scans, as well as a linear mirror, suitable for vertical scan at the typical video refresh rate (60 Hz), have been fabricated by Silicon-on-Insulator technology and are illustrated in this paper. We have in particular exploited the potentialities of semiconductor laser self-mixing interferometry, a powerful technique for characterizing the dynamic response of MEMS, for detecting the electromechanical response of both kinds of micromirrors. We report the results of the spot optical measurements performed on resonant and linear mirrors aimed at detecting the frequency of the fundamental rotational mode as well as of the in-plane and out-of-plane modes, close in frequency to the fundamental mode. We have experimentally demonstrated that the fabricated devices are suitable for high-resolution miniaturized projectors, in terms of frequency response and scanning angle.

MEMS-based surface mounted health monitoring system for composite laminates

Abstract Composite structures subjected to extreme loadings like, e.g., impacts, can undergo a reduction of their stiffness and strength properties, due to the nucleation and subsequent propagation of cracks along the interfaces between different phase materials. This phenomenon turns out to be difficult to detect through cheap monitoring procedures. Here, we discuss a methodology to monitor the state of crack-containing composite laminates through low-cost, commercial off-the-shelf MEMS accelerometers. By adopting cyclic loading conditions, we track the evolution of the cracked, or debonded region in a double cantilever beam; this is achieved by surface mounting a MEMS (along with its board) and by monitoring the drift in the compliance of the specimen induced by crack growth. The methodology is validated through an analytical model of the experimental test, which highlights the sensitivity of the monitoring scheme to the crack length.

Investigation of the Effectiveness and Robustness of an MEMS-Based Structural Health Monitoring System for Composite Laminates

Failure of layered composites can be triggered by small inner defects; such defects can be present inside the composite from the beginning, or can be incepted by external actions during the life cycle of the structure. Defects generally evolve, under repeated loadings, into a delamination or debonding between adjacent laminae, and cannot be easily detected as they are masked by the composite skin: ad hoc health monitoring systems are therefore required. To prevent any distortion of the composite microstructure, which may trigger by itself the nucleation of the aforementioned defects, sensors should not be embedded inside the composite; in addition, to avoid a mechanical interaction between the monitoring system and the structure, sensors should be as lighter as possible. To comply with these two major requirements, we have recently investigated a microelectromechanical system-based, surface-mounted health monitoring strategy for laminates. In this paper, we provide the results of an experimental campaign to show the effectiveness of this strategy, in terms of sensitivity to the length of delamination in standard specimens (independently of the loading conditions at the tip of the delamination), and its robustness, in terms of repeatability of the outcomes relevant to the monitored state. The experimental data are compared with analytical predictions based on beam bending theory, showing a good accuracy.

Sensor deployment over damage-containing plates: A topology optimization approach

Health monitoring systems for composite laminates should detect in real-time if damage, typically consisting of delamination (i.e. debonding between adjacent laminae), is incepted or growing under the external actions. To avoid detrimental effects on the overall structural strength induced by embedded sensors, we recently proposed a surface-mounted monitoring scheme adopting microelectromechanical systems (MEMS) devices. We already investigated the capability of this methodology to detect the inception/growth of delamination in a standard test geometry; in this article, we instead focus on the optimization of sensor deployment over flexible plates, so as to maximize the sensitivity of the monitoring system to damage/delamination. This is achieved through a topology optimization approach. For a square thin plate, either supported or clamped along its boundary, we present optimal distributions of MEMS sensors to detect a damage of known or unknown position. We show that, no matter what the location, size, and shape of the damaged area are, a trivial solution consisting of an array of evenly spaced sensors does not represent the optimal one to monitor the structural health.

Lid-Integral Cold-Plate Topology: Integration, Performance, and Reliability

We demonstrate the lid-integral silicon cold-plate topology as a way to bring liquid cooling closer to the heat source integrated circuit (IC). It allows us to eliminate one thermal interface material (TIM2), to establish and improve TIM1 during packaging, to use wafer-level processes, and to ease integration in first-level packaging. We describe the integration and analyze the reliability aspects of this package using modeling and test vehicles. To compare the impact of geometry, materials, and mechanical coupling on warpage, strains, and stresses, we simulate finite element models of five different topologies on an organic land-grid array (LGA) carrier. We measure the thermal performance in terms of thermal resistance from cold-plate base to inlet liquid and obtain 15 mm2 K/W at 30 kPa pressure drop across the package. We build two different topologies using silicon cold-plates and injection-molded lids. Gasket-attached cold-plates pass an 800 kPa pressure test, and direct-attached cold-plates fracture in the cold-plate. The results advise to use a compliant layer between cold-plate and manifold lid and promise a uniformly thick TIM1 layer in the Si–Si matched topology. The work shows the feasibility of composite lids with integrated silicon cold-plates in high heat flux applications.

A Silicon Microsystem for Generation of Infrared Patterned Light

The use of patterned light for three-dimensional (3D) imaging and movement tracking has been in the last decade object of experimental investigations for industrial, scientific, and consumer applications. In this paper, we demonstrate the functionality of a compact silicon microsystem for patterned light generation suitable for 3D imaging. It incorporates a single-axis torsional MEMS mirror for steering a near-infrared beam on a diffractive silicon microstructure that projects light patterns on the target. We, here, report images, acquired with a CMOS camera, of the detected light patterns realized with different diffractive elements. As an example of application, we have illuminated 3D objects with a generated line pattern and then detected the deformation of the projected lines with the same camera. By image processing, from the line deformation, we have estimated the object depth that was found in agreement with the geometrical size.

Lid-Integral Cold Plate Topology Integration, Performance, and Reliability

We demonstrate the Lid-Integral Silicon Coldplate topology as a way to bring liquid cooling closer to the heat source IC. It allows to eliminate one thermal interface material (TIM2), to establish and improve TIM1 during packaging, to use wafer-level processes, and to ease integration in 1st level packaging. We describe the integration, and analyze reliability aspects of this package using modeling and test vehicle builts. To compare the impact of geometry, materials and mechanical coupling on warpage, strains and stresses, we simulate finite element models of five different topologies on an organic LGA carrier. We measure the thermal performance in terms of thermal resistance from coldplate base to inlet liquid and obtain 15mm2K/W at 30 kPa pressure drop across the package. We build two different topologies using silicon coldplates and injection molded lids. Gasket-attached coldplates pass an 800 kPa pressure test, direct-attached coldplates fracture in the coldplate. The results advise to use a compliant layer between coldplate and the manifold lid and promise a uniformly thick TIM1 layer in the Si-Si matched topology. The work shows the feasibility of composite lids with integrated silicon coldplates in high heat flux applications.Copyright

Biomarkers in neomark European project for oral cancers

Oral cavity cancers are the seventh tumor by diffusion worldwide with more than 90 % being diagnosed as oral squamous cell carcinomas (OSCCs). According to the latest WHO statistics, OSCC accounts for 5 % of the cancer deaths worldwide, being the eighth more lethal cancer entity. Early identification of cancer relapses would have the potentiality to improve the disease control and the patient survival. NeoMark is a European co-funded research project (Seventh Framework Program, Information and Communication Technologies: EU-FP7-ICT-20072-22483-NeoMark) that has the objective to identify relevant biomarkers of OSCC recurrence. It integrates high-throughput gene expression analysis in tumor cells and IT-assisted imaging with traditional staging and follow-up protocols to improve the recurrence risk stratification and to obtain the earlier identification of locoregional relapses. The architecture of the project is based on the following key points: – Creation of a web application tool: a unified interface that helps the storage and management of all information – NeoMark database: the heterogeneous NeoMark data (demographics and risk factors; clinical, pathological, and immunohistochemical parameters; filtered and cleaned genomic and imaging data) are stored in a single database – the M.J.R. da Fonseca Link Consulting – Tecnologias De Informacao S.A., Lisbon, Portugal e-mail: manuel.fonseca@link.pt M. De Fazio STMicroelectronics, Agrate Brianza (MI), Italy e-mail: marco.de-fazio@st.com 730 T. Poli et al.