N. Pitrone

Magnetic Fluids and Their Use in Transducers

Magnetic fluids are now widely used to implement transducer architectures. These fluids have valuable properties compared to traditional materials. In this column, a brief overview of magnetic fluids and their traditional uses in the field of transducers are given and some applications developed at the DIEES laboratory at the University of Catania, Italy are presented

Ferrofluidic Pumps: A Valuable Implementation Without Moving Parts

The use of magnetic fluids in transducers is of great interest due to the possibility of implementing highly reliable and reconfigurable sensors and actuators. Examples of ferrofluidic transducers are available in several contexts from the detection of inertial quantities to assorted bioapplications. This paper addresses a novel architecture implementing a ferrofluidic pump intended for several purposes, including fluid control in bioapplications. The proposed architecture can be used to realize discrete and integrated pumps. The strategies that led to the implementation of the device are highlighted, along with theoretical considerations. The real prototype developed and the setup adopted for its characterization are also presented, along with experiments aimed at estimating the performance of the device.

Optimal improvement in bistable measurement device performance via stochastic resonance

The notion of noise-activated systems has been well known since the 1950s. A number of natural phenomena have been investigated by means of this theory and an improvement in the performance of several systems has also been achieved. Recently the stochastic resonance (SR) phenomenon was introduced as an innovative approach for both understanding the behaviour and improving the performance of several classes of systems. In the present work some new results regarding the influence of forcing signal parameters on the persistence of the SR condition are given. Both theoretical results and numerical simulations have been carried out to emphasize the suitability of the proposed noise tuning methodology.

Bent beam MEMS Temperature Sensors for Contactless Measurements in Harsh Environments

A novel MEMS temperature sensor based on a cascade three-stage bent beam structure is described in this work. Three cascaded systems compose the structure in order to enhance sensor sensitivity. The structure is mechanically deforms as a response to the change in the ambient temperature and then a displacement is obtained that is furthermore amplified by the cascaded architecture. The final conversion is toward an electrical signal that is obtained by using an interdigited capacitor embedded into the moving tip of the MEMS sensor. The device has been conceived to operate into high temperature environments and to be remotely read-out. An external coil inductor has been figured out in this first prototype to realize a resonant LC circuit, where the capacitor changes with the temperature to be measured, and which can remotely be tuned with a magnetically coupled circuit reader. Analytical and numerical models have been developed and preliminary experimental results are reported here to show a good accordance with expectations. Vernier scales have been suitably positioned to quantify the deformations during the first characterization phase such to perform a comparison with the expected behavior.

Stand-alone laboratory sessions in sensors and signal processing

Real laboratory experiments can help students to gain a better understanding of theoretical problems. Great efforts are needed, however, to improve the quality of laboratory sessions, and a large number of tutors are usually required. Moreover, students may lose time because of hardware failure or an inefficient experimental setup. Several educational tools (based on virtual instruments) have been developed allowing for optimized time scheduling and remote access to laboratory sessions. Drawbacks related to hardware failure have not, however, been seriously addressed. This paper proposes an educational tool made up of a user-friendly interface controlling experimental boards. It basically consists of an array of optical sensing devices connected to suitable conditioning circuits, which are interfaced to a virtual instrument by means of a data acquisition system. To solve the previously mentioned drawbacks, a solution based on both pre-cabled hardware and PC-based measurement stations has been adopted. Moreover, the ability to configure self-educational tasks optimizes time scheduling for students during laboratory activities. The proposed system allows students to improve their knowledge in the field of optical sensing devices, virtual instrumentation, data acquisition systems, and signal processing. The paper describes an application of the tool as a simple system for surface recognition. This application is one of the laboratory tasks performed in measurement classes during this engineering course at the University of Catania, Catania, Italy.

Models for air quality management and assessment

Models which could be useful for estimating air pollutant concentrations as a function of the emission distribution and the attendant meteorological conditions have been investigated. The integration of this model into an emission control scheme for the control of the pollution sources may represent a very useful approach to air quality management and assessment. A novel black box approach for air pollution modeling has been proposed. The main target of this approach is the prediction, on the basis of meteorological forecasts, of the air pollution concentration as a function of the expected causes.

Measurements of parameters influencing the optimal noise level in stochastic systems

Noise-added systems exhibit interesting features in many application fields. In particular, the Stochastic Resonance (SR) phenomenon has been introduced as an innovative approach to understand the behavior and to improve the performance of several classes of systems. In this paper, a new procedure to determine the parameters that influence the optimal level of the noise assuring suitable performances is proposed. The method has been implemented by using a virtual instrument. It enables the determination of the parameters to be carried out via the collection of a very small number of measurements. Both virtual and analog tools, allowing the noise level control, are proposed and a case study is reported.

A novel measurement strategy for volcanic ash fallout estimation based on RTD Fluxgate magnetometers

An innovative solution to measure the fallout of ETNA erupted volcano particles based on Residence Times Difference fluxgate magnetometer is here presented. The approach adopted is based on the exploitation of intrinsic magnetic properties of the emitted particles using a FR4 (flame resistant 4) fluxgate structure embedding a high permeability magnetic layer (Metglasreg ribbon, 1.6 mm thick) between two standard metallized layers. The proposed measurement system, for volcanic ash fallout estimation, represents an innovative direct sensing methodology, different from other current approaches that generally estimate the material in suspension and evaluate the expected fallout by using numerical models, such as satellite imaging, radar observations, Geostationary Operational Environmental Satellite, Moderate Resolution Imaging Spectroradiometer and the Atmospheric Infrared Sounder. The experimental set-up is here described and some preliminary results are reported to show the suitability of the approach proposed.

Development of novel ferrofluidic pumps.

The development and realization of micropipettes and micropumps has captured the interest of people working in both biomedical and chemical areas for the capability of managing very low quantity of liquid (drug, biological liquid or expensive reagent) as well as everyone interested in controlling small flows for dedicated applications. In this paper a novel ferrofluidic pump adopting an electromagnetic actuation is proposed. The pump is realized by injecting three drops of ferrofluids into the pipe (two valves and a plunger are required) in the position where the pump must operate and by exploiting the forces produced onto each ferrofluid drop by some coils externally placed with respect to the pipe. The absence of any mechanical moving parts, the possibility to realize a volumetric pump in a section of an existing pipe without interruptions and deformation are the main advantages of the architecture proposed as compared to existing prototypes. A detailed description of the strategy proposed is presented along with a preliminary characterization of the prototype developed

Threshold error reduction in linear measurement devices by adding noise signal

The threshold error in electro-optical devices represents a serious problem in many applications and should be kept as low as possible for optimal system performance. In the past the authors have investigated the possibility of improving the performances of bistable systems by using Stochastic Resonance (SR) theory. In particular, the possibility of extending the threshold error reduction approach from bistable systems to a wider class of systems has been investigated for a significant improvement of the performances of several measurement devices such as optical sensors, environmental sensors, and proximity sensors. In this paper the reduction of threshold error in an optical transducer is taken into account. A methodology based on noise modulation of the input signal is presented. Experimental results are reported in order to emphasise the suitability of the proposed methodology.