Showing papers by "Marco Parvis published in 2009"

Monitoring of the primary drying of a lyophilization process in vials

Abstract: An innovative and modular system ( LyoMonitor ) for monitoring the primary drying of a lyophilization process in vials is illustrated: it integrates some commercial devices (pressure gauges, moisture sensor and mass spectrometer), an innovative balance and a manometric temperature measurement system based on an improved algorithm (DPE) to estimate sublimating interface temperature and position, product temperature profile, heat and mass transfer coefficients. A soft-sensor using a multipoint wireless thermometer can also estimate the previous parameters in a large number of vials. The performances of the previous devices for the determination of the end of the primary drying are compared. Finally, all these sensors can be used for control purposes and for the optimization of the process recipe; the use of DPE in a control loop will be shown as an example.

A Wireless Sensor Network for Cold-Chain Monitoring

Abstract: This paper deals with a wireless sensor network that was specifically designed to monitor temperature-sensitive products during their distribution with the aim of conforming to the cold-chain assurance requirements. The measurement problems and the constraints that have been encountered in this application are initially highlighted, and then, an architecture that takes such problems into account is proposed. The proposed architecture is based on specifically designed measuring nodes that are inserted into the products to identify their behavior under real operating conditions, e.g., during a typical distribution. Such product nodes communicate through a wireless channel with a base station, which collects and processes the data sent by all the nodes. A peculiarity of the product nodes is the low cost, which allows the information on the cold-chain integrity to be provided to the final customer. The results that refer to the functional tests of the proposed system and to the experimental tests performed on a refrigerated vehicle during a distribution are reported.

Plastic optic fiber sensor for cumulative measurements

Abstract: Sensors are typically designed to produce outputs related to the instantaneous value of the quantity of interest; however situations exist where an output related to the total, cumulative or 'integral' exposure to the quantity of interest is required. This paper describes a low-cost optical sensor for the monitoring of the total exposure to sulphide vapors exploiting a non-reversible chemical reaction and the evanescent field absorption in plastic optical fibers. The sensor is particularly suited for extensive use in cultural heritage conservation monitoring, being intrinsically safe and also quite cheap since the interrogation does not require coherent light sources and spectral analysis. Some prototypes of the proposed sensing system have been produced and tested in laboratory, obtaining a good sensitivity and a fast response.

Environmental monitoring of heritage buildings

Abstract: A system for the monitoring of microclimate and air pollutant concentrations in heritage buildings has been developed and validated by means of a measurements campaign in the Villa della Regina, a Savoy residence in Torino. The in situ campaign is currently in progress in cooperation with the Soprintendenza per i Beni Storici, Artistici ed Etnoantropologici del Piemonte. The monitoring system is composed of a wireless network of smart buttons, specifically designed to satisfy the requirements for applications in the field of cultural heritage. The smart button sensors are configured to measure temperature and humidity. Some sensor prototypes equipped also with a POF sensor for the detection of Hg vapors have been developed and are being tested in laboratory.

A low-invasive system for local temperature mapping in large freeze dryers

Abstract: This paper deals with low-invasive temperature monitoring inside freeze dryers. During lyophilization, both the temperature of the freeze-dryer shelves and the temperature of the products have to be measured in order to control the process and to guarantee the product quality. In addition, temperature measurements are essential to obtain reliable information during the development of the freeze-drying receipt and to scale-up the process from the laboratory to the industrial scale. Unfortunately, many constrains make such measurements extremely difficult and not many measuring systems are available; in the paper the main problems related to the temperature measurements, along with some available solutions, are discussed. Then, a low invasive measurement system, that has been specifically developed to measure both the required temperatures, is presented and described.

Plasma deposited thermocouple for non-invasive temperature measurement

Abstract: This paper describes the realization of a temperature sensor based on plasma sputtered thermocouples. The thermocouples are realized in the vacuum with quite pure materials, negligible oxydation and with low contamination thus enabling accurate measurements and are made inert by means of a thin coating of tetraethoxysilane (TEOS) that seals them. The thermocouples have an overall thickness of few hundreds of nanometers and are designed to allow non invasive, though accurate temperature measurement to be obtained in adverse conditions, such as the ones found during lyophilization processes. Lyophilization is widely employed to obtain pharmacological active powders in an economical and massive way. The lyophilization process effectiveness depends on the thermal distribution inside the lyophilizing vials: if the temperature is too low the process become extremely slow thus greatly increasing the powder cost, but if the temperature is too high a melting of the frozen substance can occur that can make the powder useless. Tuning the drying process is therefore extremely important, but such an operation is quite difficult since the temperature greatly changes inside each lyophilizing vial due to the process itself and among vials due to their position within the apparatus. A local temperature measurement would therefore be necessary, but normal temperature sensors would alter the drying local condition making the measurement incorrect and indirect measurements proved to be not reliable. The proposed solution instead is almost inert, capable of performing accurate local measurements and can be used in a variety of conditions where size and possible contamination are of importance. A sensor prototype is described and its performance compared with conventional sensors highlighting the advantages of the proposed solution.

Measurement Procedures for the Electrical Characterization of Oxide Thin Films

Abstract: This paper describes a measurement system for the electrical characterization of oxide thin films. Such films can be produced using plasma-sputtering processes and permit the realization of a large set of high-performance components, such as capacitors, active devices, sensors, and protective coatings. The electrical properties of the oxide films, which have a thickness of less than 1 mum, are difficult to measure since very high resistances (on the order of giga ohms) and small capacitances (on the order of picofarads) are expected for contact areas smaller than 1 mm2 . The measurement system and the procedures described in this paper represent an alternative solution to the commercial devices, which usually employ a mercury probe for performing the contact with the specimen under characterization. Furthermore, the proposed system can be used not only to estimate the electrical properties of a single point but to evaluate the uniformity of oxide films on large specimens as well. The experimental results reported refer to valve-metal-based oxide films deposited in a lab-scale capacitively coupled parallel-plate reactor and show the effectiveness of the proposed procedures.

A Grid Architecture for Efficient Measurement of Electrical Disturbances

Abstract: This chapter deals with the extension of the grid paradigm to distributed measuring systems. The main problems that arise when distributed measuring systems are configured as grid are discussed and a solution is also proposed in order to integrate measuring nodes with low processing capabilities in a grid architecture. The problem that is mainly discussed in the chapter is that related to the configuration of the grid that allows good performance to be obtained in terms of processing time. An example application is developed, consisting of a system for measuring conducted disturbances of electrical equipment, which is based on a parallel processing algorithm. A grid architecture has been deployed in order to implement the proposed algorithm and a specific service has been developed, whose task is the choice of the processing strategy that minimizes the total processing time. Experimental results are also provided that refer to a real scenario.