AI-Assisted Design and Experimental Testing of a Compact UWB Antenna for the Inspection of Food and Beverage Products

Detecting physical contamination caused by low-density foreign bodies is an ongoing challenge faced by the food and beverage industries. To overcome the limitations of existing devices, a novel detection principle based on microwave imaging (MWI) has been assessed. MWI enables safe and non-invasive analysis of the sample under test through a 3-D reconstruction obtained from the alteration that the electromagnetic scattered waves undergo due to the presence of a foreign body. To make the application of this technology more appealing in real-world scenarios, we propose an antenna that can cover a broad set of food types, permitting the adaptability of the system's operating frequency depending on the products' dielectric properties and the containers' type or shape. The proposed antenna is designed with the help of artificial intelligence (AI). Thanks to its low cost and small dimensions, we can increase the quantity of acquired information by increasing the number of antennas placed around the product. A complete functioning system using the designed antenna is presented, assessing the image reconstruction in a case with realistic products and contaminants

Novel Christmas Branched Like NiO/NiWO4/WO3 (p–p–n) Nanowire Heterostructures for Chemical Sensing

Establishing a platform comprising different nanostructured oxides is an emerging idea to develop highly sensitive and selective sensing devices. Herein, novel 3D-heterostructures (p–p–n) consisting of 1D nanowires of NiO and WO3 along with their intermediate reactive product, i.e., NiWO4 seed, are produced by a two-steps vapor phase growth method. In-depth morphological and structural investigations describing the growth mechanism of these heterostructures are presented. Finally, the p–p–n heterostructures are integrated into conductometric sensing devices and their performances are investigated toward different gases. It is observed that by modulating the charge-carrier transport with temperature, the heterostructure sensors exhibit selective behavior toward different gas analytes. Indeed, at 300 °C, the heterostructure sensors show relatively selective behavior toward NO2, while at 400 °C, high selectivity toward VOCs is observed. The improvement in sensing performances is mainly based on charge carrier transport through the two interfaces (one at WO3/NiWO4 (n–p) and the other at NiWO4/NiO (p–p)) and the modulation of charge carriers in the electron depletion layer of WO3 and hole accumulation layer of NiO and NiWO4. The remarkable performance of these complex heterostructures with low ppb-level detection limits makes them excellent candidates for chemical/ gas sensing applications in e-noses

Fabrication of CuO (p)–ZnO (n) Core–Shell Nanowires and Their H2-Sensing Properties

: Unlike the conventional one-dimensional (1D) core-shell nanowires (NWs) composed of p-type shells and n-type cores, in this work, an inverse design is proposed by depositing n-type ZnO (shell) layers on the surface of p-type CuO (core) NWs, to have a comprehensive understanding of their conductometric gas-sensing kinetics. The surface morphologies of bare and core-shell NWs were investigated by field emission scanning electron microscope (FE-SEM). The ZnO shell layer was presented by overlay images taken by electron dispersive X-ray spectroscopy (EDX) and high-resolution transmission electron microscopy (HRTEM). The pronounced crystalline plane peaks of ZnO were recorded in the compared glancing incident X-ray diffraction (GI-XRD) spectra of CuO and CuO-ZnO core-shell NWs. The ZnO shell layers broaden the absorption curve of CuO NWs in the UV-vis absorption spectra. As a result of the heterostructure formation, the intrinsic p-type sensing behavior of CuO NWs towards 250 and 500 ppm of hydrogen (H2) switched to n-type due to the deposition of ZnO shell layers, at 400 °C in dry airflow

Revolutionizing n-type Co3O4 Nanowire for Hydrogen Gas Sensing

This study presents conductometric sensors based on Co3O4 nanowires for hydrogen detection at ppb levels. The nanowires are synthesized through thermal oxidation of a 50 nm cobalt layer, exhibiting diameters between 6-50 nm and lengths of 1-5 & mu;m, primarily growing along the (311) direction of spinal Co3O4. Raman investigation reveals five characteristic peaks at 195, 482, 521, 620, and 692 cm(-1), corresponding to symmetric phonon modes of crystalline Co3O4. Electron paramagnetic resonance measurements confirm the presence of a ferromagnetic phase, attributed to incomplete cobalt oxidation, which disappears after 8 h of thermal aging at 400 & DEG;C. Conductometry measurements are performed in the temperature range of 300-500 & DEG;C. At temperatures above 300 & DEG;C, sensors exhibit abnormal n-type semiconducting behavior due to lattice oxygen's involvement in the hydrogen sensing mechanism. Operating at 450 & DEG;C in dry air, the sensor shows a higher 232% response to 100 ppm H-2 compared to ethanol, acetone, methane, carbon monoxide, and nitrogen dioxide. Remarkably, the sensor maintains a consistent conductance baseline even under high humidity (90%) for 25 d, with three-cycle repeatability. This distinctive gas-sensing capability is attributed to the catalytic activity and elevated operating temperature

Biodegradability of superparamagnetic nanoparticles of iron oxide used as MRI contrast agents in organic tissue and intra-cellular environments

International audienc

Pattern formation on silicon by laser-initiated liquid-assisted colloidal lithography

We report sub-diffraction limited patterning of Si substrate surfaces by laser-initiated liquid-assisted colloidal lithography. The technique involves exposing a two-dimensional lattice of transparent colloidal particles spin coated on the substrate of interest (here Si) immersed in a liquid (e.g. methanol, acetone, carbon tetrachloride, toluene) to a single picosecond pulse of ultraviolet laser radiation. Surface patterns formed using colloidal particles with different radii in the range 195 nm ≤ R ≤ 1.5 μm and liquids with differing indices of refraction (n liquid) are demonstrated, the detailed topographies of which are sensitively dependent upon whether the index of refraction of the colloidal particle (n colloid) is greater or smaller than n liquid (i.e. upon whether the incident light converges or diverges upon interaction with the particle). The spatial intensity modulation formed by diffraction of the single laser pulse by the colloidal particles is imprinted into the Si substrate

Simple ethanol refluxing method for production of blue-colored titanium dioxide with oxygen vacancies and visible light-driven photocatalytic properties

We show that a simple ethanol (EtOH) refluxing treatment at mild temperature (120 °C) allows producing blue-colored and reduced titanium dioxide (TiO2−x) exhibiting improved visible-light (VIS) photocatalytic properties. The treatment causes an increase in the density of Ti(III) species and the appearance of two optical absorption features: a broad absorption band-responsible for the blue coloration- extending from the green region (-2.3 eV) up to the near-infrared and a subgap absorption tail close to the band gap energy. The experimental results combined with a computation of the density of states via hybrid Hartree−Fock density functional support the hypothesis that the EtOH reflux treatment leads to formation of surface and subsurface oxygen (O) vacancies. We also show that the excitation-resolved photoluminescence technique allows a high-contrast detection of a subgap optical excitation band peaked at about 430 nm (-2.9 eV), associated with anatase photoluminescence, whose intensity increases after the EtOH reflux treatment. This result gives a very direct support to the debated hypothesis identifying O vacancy states as the energy levels involved in the radiative transition of anatase TiO2. Improved photocatalytic degradation by the processed TiO2 under VIS illumination is demonstrated, and the possible mechanism involved in the formation of surface O vacancies is discussed. The method outlines a very simple, low-cost, and fast procedure to target the formation of O vacancies in the TiO2 surface region