MONITORING SYSTEM FOR UNDER-WATER PIPE LINE

The growing interest in new under-water pipe lines for the delivery of natural gas (in Baltic Sea, Mediterranean region, Caspian Sea, Black Sea, etc.) needs a new instruments for the monitoring of leakage and/or possible destruction of the pipes, which could not only disturb fragile ecological systems of Baltic and other seas, but also can lead to the technological catastrophes. We plan to develop a prototype of the system consisting of pervaporation membrane and gas sensors. Overall system will be immersed into water and will be fabricated in two versions: as a stationary instrument dipped into sea water and as an instrument towed along the pipe line. Micromachined metal oxide semiconductor gas sensors used for the detection of methane concentrations is designed and fabricated using “nano-on-micro” approach. Overall system is optimized from the point of view of minimum power consumption, which is necessary to assure its long term operation under autonomous conditions

A Silicon micromachined alcoholometer

This research work was aimed to find an innovative process based on MEMS technologies to measure the alcoholic strength of hydro-alcoholic solutions. A new Silicon micromachined alcoholometer was developed. A microhotplate based on dielectric thin membrane is used to heat and measure the temperature of droplets of hydro-alcoholic solution dispensed by a tiny capillary during an evaporation cycle. It was found that the alcoholic strength is correlated with the integration of the temperature of the droplet over time during its evaporation. Opposed to the old measurement methods this new procedure takes advantage of many properties of the hydro-alcoholic solutions such as: superficial tension, latent heat of evaporation, boiling point and heat capacity. All these issues contribute together to give a good response in terms of good resolution and accuracy over a wide range of alcoholic degree

Stability control of an historical structure with TLS survey

In this paper we present the preliminary results of a study aimed to assess the stability of a complex historical structure such as the Anatomy Theatre. The construction occupies the two upper floors on the north west side of Palazzo del Bo\u2019, the building seat of the University of Padua. The Anatomy Theatre is certainly one of the oldest, most important and best-known historical \u201cmedical\u201d buildings. Built in 1594, the Theatre was the first permanent structure of its kind and substituted for the temporary theatres which were set up when necessary. The main goal of this work is to verify the stability over the time of this kind of structure, given the inherent organic decay of the wooden parts. Although this task could be performed with classical surveying methods, a long-range terrestrial laser scanner (Leica HDS 3000) was employed. This choice was dictated by considering the numerous measurement benefits offered by TLSs, such as three-dimensional data capture, remote and noncontact (i.e. targetless) operation and dense data acquisition. The presented work is part of a wider project aimed not only at the checking of the structure stability but also at the structural assessment through the use of finite element model. In the paper we will present the preliminary results obtained from the repeated checks and highlight issues and difficulties related to the laser scanning of an unusual geometry such as the one provided by the Anatomy Theatre of the University of Padua

Measurements of the mechanical properties of composite membranes by load-deflection method with a profilometer

Composite membranes are basic mechanical components frequently used in MEMS for different tasks like signal trasduction (pressure sensors), isolation (microheaters) or merely as a support (passive microwave devices). The design of membranes for these and other applications requires the exact knowledge of mechanical properties of the single materials composing the membrane, like internal stress and Young modulus. Both are influenced by process conditions and therefore have to be determined for each material. To this purpose, the membrane itself can be used as test structure. In this work the use of a commercial profilometer to conduct load-deflection measurements on composite membranes is presented. The use of the profilometer results in a simpler measurement set-up with respect to the more traditional techique of appliying a controlled pressure difference. The approach is tested on composite membranes of poly-Si and silicon nitride that were designed to this purpose and are apart of test structures that can be inclusded in a MEMS fabrication process. Internal stress measurements of poly-Si are presented and compared with measurements obtained with the cantilever beam techniqu

An innovative microalcoholometer based on AI2O4 microhotplates

The demand of on-line monitoring of processes in wine and spirit production is growing every year, as it can help to increase the quality of the goods and the efficiency of the production. The measurement of the alcoholic degree plays an important role in this field. This paper reports the development of a new Al2O3 microalcoholometer based on an innovative principle of measurement

Progettazione, disegno, fabbricazione e caratterizzazione di un microfono capacitivo in silicio con tecnologie MEMS

La realizzazione di un microfono capacitivo con tecniche micromeccaniche è un progetto complesso ed articolato, che prevede lo sviluppo contemporaneo di un design e di un processo di fabbricazione ottimali per un dispositivo elettromeccanico miniaturizzato tridimensionale a tutti gli effetti. Un simile progetto può essere suddiviso idealmente in tre grandi fasi successive: la fase di studio e preparazione, la fase di prototipazione e la fase di ingegnerizzazione. Lo scopo della prima fase è quello di acquisire le competenze di base per la progettazione dei prototipi, di preparare un primo layout e di scegliere il concetto base per il processo di fabbricazione. La fase di prototipazione ha lo scopo di implementare la tecnologia di fabbricazione e di valutarne i limiti. Inoltre questa fase è servita per analizzare le soluzioni di progetto adottate nel primo layout. La fase finale è dedicata alla realizzazione di un microfono ottimizzato per una specifica applicazione. Questo rapporto tecnico è dedicato essenzialmente alla realizzazione del secondo run di fabbricazione ed all’analisi dei risultati sperimentali ottenuti su questi prototipi. Dopo una breve ricapitolazione sugli obiettivi generali del progetto, i risultati e i problemi del primo silicio, segue una descrizione delle correzioni adottate nel secondo silicio, sia di layout, sia di processo. Il terzo capitolo è interamente dedicato ad un dettagliato resoconto sul processo di fabbricazione del secondo silicio. Il quarto capitolo riassume le misure sperimentali fatte sui prototipi e sulle strutture ausiliari di test. Segue un’analisi dettagliata dei dati da cui emergono gli elementi mancanti per la progettazione ottimale del microfono in silicio. Nella conclusione sono riassunti i risultati principali ottenuti e sono discussi tutti gli elementi necessari per completare il progetto del microfono capacitivo in silici