Istituto Nazionale di Ricerca Metrologica
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Comb-assisted mercury spectroscopy in the deep-ultraviolet: towards the development of a new primary thermometer
Get PDFData set of measurement data vs test conditions for instrument transformer performance characterised in the presence of separate and combined influence factors
No full textData set of measurement data vs test conditions for IT performance characterised in the presence of separate and combined influence factors, including concise description of measurement data and test conditions
Liquid Crystalline Network Microstructures for Stimuli Responsive Labels with Multi‐Level Encryption
Get PDFTwo-photon direct laser writing enables the fabrication of shape-changing microstructures that can be exploited in stimuli responsive micro-robotics and photonics. The use of Liquid Crystalline Networks (LCN) allows to realize 3D micrometric objects that can contract along a specific direction in response to stimuli, such as temperature or light. In this paper, the fabrication of free-standing LCN microstructures is demonstrated as graphical units of a smart tag for simple physical and optical encryption. Using an array of identical pixels, information can be hidden to the observer and revealed only upon application of a specific stimulus. The reading mechanism is based on the shape-change of each pixel under stimuli and their color that combine together in a two-level encryption label. Once the stimulus is removed, the pixels recover their original shape and the message remains completely hidden. Therefore, an opto-mechanical equivalent of an "invisible ink" is realized. This new concept paves the way for introducing enhanced functionalities in smart micro-systems within a single lithography step, spanning from storage devices with physical encryption to complex motion actuators
Designer SiO2 Metasurfaces for Efficient Passive Radiative Cooling
Get PDFIn recent years, an increasing number of passive radiative cooling materials are proposed in the literature, with several examples relying on the use of silica (SiO2) due to its unique stability, non-toxicity, and availability. Nonetheless, due to its bulk phonon-polariton band, SiO2 presents a marked reflection peak within the atmospheric transparency window (8-13 mu m), leading to an emissivity decrease that poses a challenge to fulfilling the criteria for sub-ambient passive radiative cooling. Thus, the latest developments in this field are devoted to the design of engineered SiO2 photonic structures, to increase the cooling potential of bulk SiO2 radiative coolers. This review seeks to identify the most effective photonic design and fabrication strategies for SiO2 radiative emitters by evaluating their cooling efficacy, as well as their scalability, providing an in-depth analysis of the fundamental principles, structural models, and results (both numerical and experimental) of various types of SiO2 radiative coolers
Neuronal growth on high-aspect-ratio diamond nanopillar arrays for biosensing applications
Get PDFMonitoring neuronal activity with simultaneously high spatial and temporal resolution in living cell cultures is crucial to advance understanding of the development and functioning of our brain, and to gain further insights in the origin of brain disorders. While it has been demonstrated that the quantum sensing capabilities of nitrogen-vacancy (NV) centers in diamond allow real time detection of action potentials from large neurons in marine invertebrates, quantum monitoring of mammalian neurons (presenting much smaller dimensions and thus producing much lower signal and requiring higher spatial resolution) has hitherto remained elusive. In this context, diamond nanostructuring can offer the opportunity to boost the diamond platform sensitivity to the required level. However, a comprehensive analysis of the impact of a nanostructured diamond surface on the neuronal viability and growth was lacking. Here, we pattern a single crystal diamond surface with large-scale nanopillar arrays and we successfully demonstrate growth of a network of living and functional primary mouse hippocampal neurons on it. Our study on geometrical parameters reveals preferential growth along the nanopillar grid axes with excellent physical contact between cell membrane and nanopillar apex. Our results suggest that neuron growth can be tailored on diamond nanopillars to realize a nanophotonic quantum sensing platform for wide-field and label-free neuronal activity recording with sub-cellular resolution
Influence of Mechanical Properties on the Piezoelectric Response of UV-Cured Composite Films Containing Different ZnO Morphologies
No full textZnO flower-like (ZFL) and needle (ZLN) structures were synthesized and embedded into UV-curable acrylic resin (EB), with the aim to study the effect of filler loading on the piezoelectric properties of the resulting composite films. The composites showed uniform dispersion of fillers within the polymer matrix. However, by increasing the filler amount, the number of aggregates increased, and ZnO fillers appeared not to be perfectly embedded in polymer film, indicating poor interaction with acrylic resin. The filler content increase caused an increase in glass transition temperature (T-g) and a decrease in storage modulus in the glassy state. In particular, compared with pure UV-cured EB (T-g = 50 degrees C), 10 wt.% ZFL and ZLN presented T-g values of 68 and 77 degrees C, respectively. The piezoelectric response generated by the polymer composites was good when measured at 19 Hz as a function of the acceleration; the RMS output voltages achieved at 5 g were 4.94 and 1.85 mV for the composite films containing ZFL and ZLN, respectively, at their maximum loading levels (i.e., 20 wt.%). Further, the RMS output voltage increase was not proportional to the filler loading; this finding was attributable to the decrease in the storage modulus of the composites at high ZnO loading rather than the dispersion of filler or the number of particles on the surface
Determination of sensitivity coefficients and their uncertainties in Rockwell hardness measurement: a Monte Carlo method for multiple linear regression
Get PDFIn the last few decades, many researchers have been studying how hardness measurements can be affected by possible influence variables (i.e. velocity of the indenter, dwell times, temperature, etc). This interest is particularly motivated by the newly adopted international definitions for the realization of Rockwell superficial hardness scales (HR45N, HR30N and HR15N) provided by the Consultative Committee for Mass and Related Quantities of Bureau International des Poids et Mesures, which deal with all the above-mentioned parameters. In this paper, the effect of two such parameters, namely the velocity of the final load application and the time interval of the force variation from the preliminary force value to the total force value, on superficial Rockwell hardness scales at different levels is studied and the related sensitivity coefficients are determined. The coefficients obtained are in the order of 10(-3) HR s mu m(-1) and 10(-2) HR s(-1), respectively, in agreement with other National Metrology Institutes (NMIs), i.e. NIST and NPL. However, the uncertainties associated by the other NMIs are usually underestimated since they are simply given as the standard deviation calculated from the ordinary least squares method for the multiple linear regression, or, in other cases, not reported. For this reason, we propose a methodology for calculating the uncertainties of the sensitivity coefficients via a Monte Carlo method applied to multiple linear regression in order to consider the variability of both input and output quantities: with this method, the squared uncertainties are given as the squared sum of the standard deviation calculated from the ordinary least squares method and the uncertainty contribution due to the repeatability obtained via the proposed Monte Carlo method. The proposed method yields uncertainties of about 10(-2) HR, while the uncertainties reported in other related published papers are in the order of 10(-3) HR