Istituto Nazionale di Ricerca Metrologica
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Standardized Protocol for Resazurin-Based Viability Assays on A549 Cell Line for Improving Cytotoxicity Data Reliability
Get PDFCross-comparison of the optical and acoustical calibration methods for microphones based on microelectromechanical system technologies
No full textUV-curable coatings for energy harvesting applications: Current state-of-the-art and future perspectives
No full textGenerally speaking, energy harvesting is an up-to-date technology that describes the possibility of capturing small amounts of energy (thermal, solar, or mechanical) from the surroundings and storing them as electrical energy for later uses when needed. Among the energy harvesting systems, the use of piezoelectric thin films and coatings is gaining increasing interest from both the academic and industrial communities, as these systems allow for the design and development of micro- and nano-scale devices, thanks to the possibility of being micromachined and to the added functionality offered by the electromechanical coupling. These peculiarities justify their use for different applications, ranging from high energy density harvesters to high sensitivity sensors, and even low power consumption and large displacement actuators. Further, the current focus of the research on piezoelectric energy harvesting coatings is shifting from fully inorganic to hybrid organic-inorganic (i.e., composite) systems, as the latter can offer higher flexibility (i.e., lower stiffness), making them more sensitive to small vibrations and therefore suitable for these specific harvesting conditions. In this regard, photoinduced polymerization (the so-called "UV-curing") has become a suitable and reliable technique for the manufacturing of piezoelectric composite systems, as it is a solvent-free approach that allows for transforming a liquid mixture of monomers/oligomers into a solid 3D network in a few seconds, with a very limited energy consumption and a very high conversion. Besides, as the UV-curing process is very fast, the dispersed ceramic piezoelectric phase is not prone to settle down in the liquid resin, hence ensuring its homogeneous distribution within the polymer network after curing and better piezoelectric performance. The present review aims to provide the reader with an up-to-date overview of UV-curable coatings for piezoelectric energy harvesting purposes, highlighting their potential and piezoelectric features; further, some perspectives about possible future developments will be proposed
EXTERNAL-CAVITY LASER DEVICE, CORRESPONDING SYSTEM AND METHOD
No full textA laser device (100), comprising: a source of electromagnetic radiation (S) that comprises at least one reflecting surface (RS), said source (S) being configured to generate a light beam that follows an optical path (OPa; OP) external to said source (S); a dispersive stage (6) located outside said source (S) along said optical path (OP) of said light beam generated by said source (S), said dispersive stage (6) comprising at least one axis of reflection that forms an angle (Θ; cp) with said optical path (OPa; OP) of said light beam and being configured to reflect: at least a first spectral portion of said light beam generated by said source (S) towards said source (S); and a second spectral portion of said light generated by the source (S) along said axis of reflection, wherein said at least one reflecting surface (RS) and said dispersive stage (6) form at least one variable-length external optical cavity (RS, L, 6); at least one collimating lens (C) located along said optical path (OPa; OP) and configured to collimate said light beam coming from said source (S); a collimator module (3), in which said source (S) and said at least one collimating lens (C) are mounted; and an actuator (24) configured to vary a length (L) of said a variable-length external optical cavity (RS, L, 6). In said device: said actuator (24) is mechanically coupled to said collimator module (3); and said actuator (24) is configured to vary the length (L) of said at least one external optical cavity of the variable-length gain medium (RS, L, 6) by moving said collimator (3)
A quantitative approach to reflectance transformation imaging in profilometric applications
No full textReflectance transformation imaging (RTI) is a technique employed to assess both the intensity and directional properties of light reflected from an object, aiming to visualize an object under different incident light directions. This technique has quickly become a commonly used approach for the documentation, acquisition and deciphering for cultural heritage objects, because it enables to enhance and highlight image details. The output of this mathematical synthesis technique, which elaborates illumination information, is contained in a pseudocolour image called normal map. Starting from this image, this technique allows to obtain the reconstruction of the outline of semi-flat objects by integrating the normal map given by the RTI, i.e. normal integration. The technique of normal integration has been known for many years, being widely used in graphical modelling across various fields of 3D imaging. In the context of cultural heritage, this particular form of 3D modelling has already found application in the reconstruction of semi-flat objects, albeit with some limitations in the accurate portraying of low spatial frequencies. However, quantitative and systematic studies on the efficiency of 3D rendering of objects using RTI and normal integration have not yet been conducted. In the context of this research, the quantitative evaluation of the accuracy of the RTI technique with normal integration for profilometric applications on semi-flat objects is proposed and a study on its fidelity in reproducing the considered artefact is conducted. For this purpose, ad hoc profilometric targets were designed, realized and analysed to quantitatively compare the results of RTI and normal integration with different standardized techniques: micro-photogrammetry, laser scanning and optical profilometry. Graphical abstract: (Figure presented.
Heat Transfer Mechanisms and Contributions of Wearable Thermoelectrics to Personal Thermal Management
No full textThermoelectricity can assist in creating comfortable thermal environments through wearable solutions and local applications that keep the temperature comfortable around individuals. In the analysis of an indoor environment, thermal comfort depends on the global characteristics of the indoor volume and on the local thermal environment where the individuals develop their activity. This paper addresses the heat transfer mechanisms that refer to individuals, which operate in their working ambient when wearable thermoelectric solutions are used for enhancing heating or cooling within the local environment. After recalling the characteristics of the thermoelectric generators and illustrating the heat transfer mechanisms between the human body and the environment, the interactions between wearable thermoelectric generators and the human skin are discussed, considering the analytical representations of the thermal phenomena. The wearable solutions with thermoelectric generators for personal thermal management are then categorized by considering active and passive thermal management methods, natural and assisted heat exchange, autonomous and nonautonomous devices, and direct or indirect contact with the human body
Traceability for indentation measurements in Brinell-Vickers-Knoop hardness
Get PDFHardness is an important material property describing a material's resistance to localized deformation from an indenter pressing or scraping against its surface. It is determined by measuring the indentation size realised on the tested material surface. This can be done by different hardness testing methods, like the Brinell, Vickers and Knoop scales. This project will investigate the indentation measurement phenomena for the above-mentioned scales to provide a better defined, more consistent, unified, and reliable measurement and traceability methodology to overcome the inconsistency between national metrology institutes (NMIs) and lower levels of indentation (hardness) measurements. The project outcomes will be used in the next generation of hardness definitions, instrumentation and standardisation to improve the accuracy of material testing in all engineering fields, including aerospace, automotive, health, industry and research and development
Development of Ti/Au Transition-Edge Sensors for Single-Photon Detection
Get PDFTransition-edge sensors (TESs) have shown remarkable energy resolution and photon-number resolving ability. In this paper, we report the fabrication and characterization of Ti/Au optical TESs for the detection of single photon at the telecommunication wavelength 1550 nm. A SiO2/SiNx antireflection coating is deposited on top of TESs by an inductively coupled plasma-assisted plasma-enhanced chemical vapor deposition (ICP-PECVD) process to improve the detection efficiency. Ti/Au (50/60 nm) TES with a small sensitive area 10 mu mx 10 mu m shows an energy resolution of 0.12 eV. The TES with a large sensitive area 20 mu mx 20 mu m can discriminate up to 55 incident photons and the detection efficiency is 46%
Development of miniaturised sensors for methane detection at trace levels for environmental monitoring applications
Get PDFMethane (CH4) is the second most important greenhouse gas in the Earth’s atmosphere. Anthropic emissions of
CH4 mainly come from the agricultural and energy sectors. The monitoring of CH4 low-level emissions is
fundamental to detect possible CH4 leakages from industrial/energy plants, or from natural sources. The
development and metrological characterisation of innovative sensors for detecting trace levels of CH4 is chal
lenging and promising. At INRiM a research activity on miniaturised sensors for CH4 is ongoing, with support of
Piemonte Orientale University “A. Avogadro” (UPO). The plasmonic amplification of the absorbance spectrum of
CH4 (surface-enhanced infra-red absorption - SEIRA) in the proximity of metallic microstructured components is
exploited and different SEIRA platforms are under characterisation by means of Fourier transform infra-red
spectroscopy. The experimental setup and some preliminary results concerning the development of gastrapping porous organic frameworks are presented in this work