Research | Caratterizzazione Elettromagnetica dei Materiali

Mission

Research activities developed within the LCEM are aimed at studying the electromagnetic properties of materials, particularly nanocomposites, and innovative components starting from understanding the physical mechanisms responsible for their electromagnetic properties.
The LCEM’s expertise covers models and techniques for the design and optimization of electrical and electronic components and systems used in various production sectors, particularly those with a high technological content.In particular, the LCEM research team has developed projects on the following topics:

• Characterisation and electromagnetic processing of innovative materials and composites
• Development of components and methods for the diagnosis of materials and components
• Development of analytical and numerical methods for the robust design of electromagnetic systems
• Development of nanotechnology-based methods and diagnostics for biomedical and biotechnology applications.

In addition, the LCEM's researchers and technical staff has the possibility to design and carry out tests on materials and components, either in accordance with international standards or on innovative technical specifications defined ad hoc.

Activities

Characterisation of insulation systems for new generation traction motorsThe work in this area has recently been focused on studying the performance of innovative insulation systems for asynchronous motor windings, powered by new generation inverters, used in high-power applications, as used in electric traction. The design constraints of such insulation systems include a high thermal class and the ability to withstand intense electrical stresses, characterized by distorted waveforms and containing steep-front pulses. The research, also carried out in collaboration with researchers and technicians from Hitachi (Naples), is focused on the study of degradation mechanisms and the evaluation of the performance of insulation systems for motor windings, and the proposal of appropriate diagnostic methods for monitoring the level of ageing. To this end, a detailed characterization of various insulation systems of industrial interest was carried out, with varying parameters of electrical stress.
Carbon-based nanocomposites for aeronautical applicationsAnother topic concerns the development of nanostructured polymer composites based on different carbon nanoparticles, such as nanotubes (CNT), nanofibres (CNF), and graphene nanosheets (GNL). These nanoparticles can be incorporated into polymer materials to improve their thermal, mechanical, chemical and especially electrical properties for applications such as electromagnetic shielding (EMI or RFI), antistatic materials and structural components in the automotive, aeronautical and aerospace sectors. This theme has been developed in various projects, such as the EU 7th FP project ""Improving the Aircraft Safety by Self Healing Stucture and Protecting Nanofillers (IASS)"" and covered both electromagnetic characterisation, the development of numerical models to assess the electrical properties of nanocomposites. On these aspects, LCEM researchers are co-holders of a European patent. Further work involves the development of sensors embedded in polymer-based composite structures with auto sensing capabilities for monitoring new generation aircraft structural parts. In particular, the piezo-resistive properties of epoxy-based nanocomposites loaded with carbon nanostructures for the realization of smart materials with sensoric capabilities were studied. The experimental results obtained in tensile and flexural stress tests on nanocomposites were correlated with those obtained from the electrical model of the material. The sensitivity of the materials was also assessed, which was higher in ac than in dc because of the material structure reflected in the electrical equivalent model.
Development of components and methods for the diagnosis of materials and componentsIn the course of the analysis of innovative insulation systems for asynchronous traction motors, appropriate diagnostic methods have been developed to monitor the level of ageing. In particular, the trends over time, with the variation of applied stresses, of some quantities of electrical nature, such as the trends of partial discharge patterns and of physical nature, such as the contact angle, are analyzed and correlated.
Development of analytical and numerical methods for the robust design of electromagnetic systemsThe activity is concerned with the development of numerical methods for tolerance analysis, tolerance design and robust design of electromagnetic circuits and systems. In particular, the possibility of applying Range Analysis Methods and Evolutionary Algorithms to the study of non-linear systems in the presence of parametric uncertainties has been studied. Subsequently, the above techniques were applied to the tolerance design of non-linear electromagnetic circuits and systems. Based on the results achieved, the problem of robust design of non-linear systems has been addressed more recently. The methods developed have also been applied to a number of industrial problems. On these aspects the researchers of LCEM are responsible for university research activities (Graphene 3D) under the ""Graphene Flagship"" a European initiative involving the most important research centres and companies involved in the exploitation of graphene properties.
Development of nanotechnology-based methods and diagnostics for biomedical and biotechnology applicationsThis topic concerns the analysis of the behaviour of biological cells subject to impulsive electric fields which are particularly interesting in different areas of medicine and biotechnology because of the possibility of introducing appropriate agents into the of the cell. The electrical parameter controlling transport properties through the cell membrane is the transmembrane voltage. The study covers models describing mechanisms of reversible or irreversible membrane permeability under electrical stress, in order to determine the most appropriate values of electrical stress to be applied to obtain specific treatment effects. Sensors for the acquisition of biomedical parameters based on field effect transistors (FETs) using thin layers of carbon nanotubes as active material have also been studied and developed. The LCEM researchers are involved in these topics under the European project COST TD114 EP4BIO2MED Electroporation.

Teaching

The following are the didactic experimental activities carried out in LCEM:

• Exercises for Electrical Technologies for Industrial Computing (Course degree Informatics Engineering - 3° year):
• Realization and characterization of circuits with Operational Amplifiers: summator, comparator (with and without hysteresis); integrator; derivator, multivibrator.
• Development and characterization of control/implementation systems based on microprocessors (Arduino, Raspberry)
• Master’s Thesis (in collaboration with ENSICAEN France) (Course degree Informatics/Electronics): Development and characterization of systems for the acquisition and processing of biometric data.
• International internships (Belgium U-MONS, France Rennes 2) Characterisation of innovative nanocomposites.
• Graduate and traineeship papers (CdL Ing. Electronics/Chemistry): Modelling and characterization of innovative nanocomposites. Electrochemotherapy and applications of electric fields to biological systems.

Equipment

The most relevant instrumentation available at LCEM is:

• Square wave high voltage generators capable of operating at 6 kV amplitudes, frequencies from 10 to 20 kHz and slew rates of 1, 2 or 3 kV/μs;
• High voltage generator dc amplitude up to 6kV and current up to 5mA;
• TREK HV amplifier mod. 20-20C, voltage up to 20kV, current up to 20mA, frequency up to 20kHz;
• Keithley multimeter model 6514 capable of measuring currents from 100aA to 21mA, resistances between 10mOhm and 210GOhm and electric charges between 10fC and 21μC;
• Keysight multimeter model B2985B able to measure currents 0.01fA at 21mA, resistance up to 1POhm and electrical charges between 1fC and 2μC
• Techimp partial discharge survey system;
• Digital oscilloscope 4 channels, 500 MHz, 5 GS/s;
• Digital oscilloscope 4 channels, 1 GHz, 10 GS/s;
• High voltage probes (probes 1000x, up to 40kV and 75MHz bandwidth);
• Galli stove mod. G35 for treatment in the range of +10 °C to +260 °C, with uniformity < 2 °C and a treatment volume of 35 l;
• BINDER Stove mod. FP53 for treatment in the range of +10 °C to +300 °C;
• Impedance analyzer Agilent mod. E4991A operating from 10Hz to 3GHz, equipped for dielectric (solid and liquid materials) and magnetic (solid materials) characterization;
• Impedance Analyzer Keysight mod. E4990A 20Hz to 10 MHz equipped with fixture for the measurement of dielectric properties;
• Dieletric analyzer Omicron mod. Spectano 100 with cell for testing up to 200°C .