ERT is a technique that determines a spatial map of the conductivity of an object by performing electrical resistance measurements between contacts placed on its boundary. We investigate both implementation (instrumentation, measurement strategies) and computational (inverse problem solving) aspects of the technique. INRIM is now developing both experimental setups and mathematical models for map reconstruction dedicated to thin-film and nanostructured materials research.

Selected publications:

• Tomography of memory engrams in self-organizing nanowire connectomes, Milano, G., et al., Nature Communications 14, 5723, 2023. [link]

• Mapping the conductivity of graphene with Electrical Resistance Tomography, A. Cultrera et al., Scientific Reports , 2019. [link]

• Mapping time-dependent conductivity of metallic nanowire networks by electrical resistance tomography toward transparent conductive materials G Milano, et al., ACS Applied Nano Materials, 2020. [link]

Electrical noise spectroscopy is an effective technique to get insigth of the microsopic structure of materials. Charge transport mechanisms can be inferred from the assessment of noise spectra without affecting the sample. Moreover, nanostructured materials show noise characteristics that reflects confinement effects. 

Selected publications:

• A correlation noise spectrometer for flicker noise measurement in graphene samples, M. Marzano et al., Meas. Sci. Technol. 30 035102, 2019. [link]

• Role of plasma-induced defects in the generation of 1/f noise in graphene, A. Cultrera et al., Appl. Phys. Lett. 112, 093504, 2018. [link]

Lock-in amplifiers are widely employed in experiments as signal recovery instruments, to measure very small signals with amplitudes down to the nanovolt range. They are not designed to be precision instruments: in fact, the typical specifications for the gain accuracy are of the order of percent. A calibration of the lock-in amplifier gain can reduce the measurement uncertainty of many experiments.

Selected publications:

• A new calibration setup for lock-in amplifiers in the low frequency range and its validation in a bilateral comparison, A. Cultrera et al.,  Metrologia 58 025001, 2021. [link]

Within the IEC/TC 113 ‘Nanotechnology in electrotechnical products and systems’, standardization activity of the technologies relevant to electrotechnical products and systems is pursued in the field of nanotechnology in close cooperation with other committees of IEC and ISO. I join the Working Group 8 "Graphene and related materials", which is aimed to the development and publication of technical specifications and international standards to implement electrical characterisation of graphene and related materials.

Selected publications:

• New IEC standards for the measurement of sheet resistance on large-area graphene using the van der Pauw and the in-line four-point probe methods, A. Cultrera, et al., Measurement,  236, 114980, 2024.  [link]

• 16NRM01 EMPIR GRACE consortium, “Good Practice Guide on the electrical characterisation of graphene using contact methods”, 2020, Edited by A. Fabricius, A. Catanzaro and A. Cultrera, ISBN: 978-88-945324-0-1, available online at: www. http://empir.npl.co.uk/grace/

• 16NRM01 EMPIR GRACE consortium, “Good Practice Guide on the electrical characterisation of graphene using non- contact and high throughput methods”, 2020, Edited by A. Fabricius, A. Cultrera and A. Catanzaro, ISBN: 978-88-945324-2-5, available online at: www. http://empir.npl.co.uk/grace/

The increasing presence of non-linear loads, which can produce strong distortions of the waveforms distributed through the electricity grid, requires paying particular attention to the effects of low power quality on the performance of active energy meters, both in residential and industrial environments. In 2021 INRIM signed an agreement on methods for the validation of energy meters in effective conditions with the Economic Development Ministry of Italy; tThe main results are summarised in a journal paper published in 2024 (see referencec below). A new agreement with the ministry started in late 2024, including issues related to electric vehicle charging stations cabinets.

Selected publications:

• Active Energy Meters Tested in Realistic Non-Sinusoidal Conditions Recorded on the Field and Reproduced in Laboratory, A. Cultrera et al., Energies, 17(6), 1403, 2024.  [link]

• A calibration-verification testbed for electrical energy meters under low power quality conditions, L. Callegaro et al.,  Measurement: Sensors, 18, 100188 2921. [link]