Open Access
Radiative cooling properties of portlandite and tobermorite: two cementitious minerals of great relevance in concrete science and technology
(American Chemical Society, 2023-06-23) Dolado, Jorge S.; Goracci, Guido; Arrese-Igor, Silvia; Ayuela, Andrés; Torres Betancourt, Angie Tatiana; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Gaitero, Juan J.; Cagnoni, Matteo; Cappelluti, Federica; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Although concrete and cement-based materials are the most engineered materials employed by mankind, their potential for use in daytime radiative cooling applications has yet to be fully explored. Due to its complex structure, which is composed of multiple phases and textural details, fine-tuning of concrete is impossible without first analyzing its most important ingredients. Here, the radiative cooling properties of Portlandite (Ca(OH)2) and Tobermorite (Ca5Si6O16(OH)2·4H2O) are studied due to their crucial relevance in cement and concrete science and technology. Our findings demonstrate that, in contrast to concrete (which is a strong infrared emitter but a poor sun reflector), both Portlandite and Tobermorite exhibit good radiative cooling capabilities. These results provide solid evidence that, with the correct optimization of composition and porosity, concrete can be transformed into a material suitable for daytime radiative cooling.
Open Access
Metageometries for polycyclic aromatic hydrocarbons detection at THz range in food systems
(IEEE, 2021) Jáuregui López, Irati; Insausti Barrenetxea, Kizkitza; Beriain Apesteguía, María José; Beruete Díaz, Miguel; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Ingeniería Eléctrica, Electrónica y de Comunicación
Polycyclic aromatic hydrocarbons, when present in food systems, have been shown to have a detrimental effect on human health, producing carcinogenic elements. So, the implementation of processes for their detection and identification is of vital importance. Nowadays, there are different methodologies for this purpose, but they consist of expensive and time-consuming processes. Due to their enhanced sensitivity and more accurate detection capability, metageometries operating in the terahertz band arise as a new methodology to identify and detect different chemical or biological substances. In this work, we propose a labyrinth metageometry able to detect different polycyclic aromatic hydrocarbons collected in European regulations as the most critical compounds with high experimental sensitivity. Our design is also capable to distinguish between different compounds at the same concentration. This work leads the way to the design of new metastructures able to improve the current detection limits, and thus obtain a new methodology, easier and less time-consuming that the actual methods.
Open Access
Fully metallic Luneburg metalens antenna in gap waveguide technology at V-band
(IEEE, 2023) Pérez Quintana, Dayan; Bilitos, Christos; Ruiz-García, Jorge; Ederra Urzainqui, Íñigo; Teniente Vallinas, Jorge; González-Ovejero, David; Beruete Díaz, Miguel; Institute of Smart Cities - ISC
This article presents the design of a flat Luneburg metalens antenna at V-band using gap waveguide (GW) technology. The metalens consists of a parallel plate waveguide (PPW) loaded with metallic pins whose height is modulated to get an effective refractive index that follows the Luneburg equation. A Groove GW (GGW) H-plane horn is used to illuminate the metalens, such that the rays are collimated and a planar wavefront is generated in the direction of propagation. Since the structure at hand is planar, it can be efficiently integrated on flat surfaces. Moreover, the fully metallic structure is mechanically robust and presents lower losses than lenses including dielectric substrates. A prototype has been fabricated and tested, simulations and experimental results are in very good agreement. The metalens yields an input reflection coefficient (S11) below −10 dB from 45 to 70 GHz, whereas the −3 dB gain fractional bandwidth is 26.2% with respect to a center frequency of 60 GHz, with a peak of 22.5 dB at 61 GHz. These features make this design an interesting solution for millimeter-wave (MMW) applications.
Open Access
Tenderness of PGI "Ternera de Navarra" beef samples determined by FTIR-MIR spectroscopy
(MDPI, 2022) Beriain Apesteguía, María José; Lozano Saiz, María; Echeverría Morrás, Jesús; Murillo Arbizu, María Teresa; Insausti Barrenetxea, Kizkitza; Beruete Díaz, Miguel; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Understanding meat quality attribute changes during ageing by using non-destructive techniques is an emergent pursuit in the agroindustry research field. Using beef certified samples from the protected geographical indication (PGI) “Ternera de Navarra”, the primary goal of this study was to use Fourier transform infrared spectroscopy on the middle infrared region (FTIR-MIR) as a tool for the examination of meat tenderness evolution throughout ageing. Samples of the longissimus dorsi muscle of twenty young bulls were aged for 4, 6, 11, or 18 days at 4 °C. Animal carcass classification and sample proximate analysis were performed to check sample homogeneity. Raw aged steaks were analyzed by FTIR-MIR spectroscopy (4000–400 cm−1) to record the vibrational spectrum. Texture profile analysis was performed using a multiple compression test (compression rates of 20%, 80%, and 100%). Compression values were found to decrease notably between the fourth and sixth day of ageing for the three compression rates studied. This tendency continued until the 18th day for C20. For C80 and C100, there was not a clear change in the 11th and 18th days of the study. Regarding FTIR-MIR as a prediction method, it achieved an R2 lower than 40%. Using principal component analysis (PCA) of the results, the whole spectrum fingerprint was used in the discrimination of the starting and final ageing days with correct maturing time classifications. Combining the PCA treatment together with the discriminant analysis of spectral data allowed us to differentiate the samples between the initial and the final ageing points, but it did not single out the intermediate points.
Open Access
Giant photodegradation rate enabled by vertically grown 1T/2H MoS2 catalyst on top of silver nanoparticles
(Wiley, 2024-08-27) Mouloua, Driss; Rajput, Nitul S.; Lejeune, Michael; Beruete Díaz, Miguel; El Marssi, Mimoun; El Khakani, My Ali; Jouiad, Mustapha; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The exaltation of the photodegradation performance of dichalcogenide MoS2 grown on top of silver nanoparticles (Ag-NPs) is reported on. The fabricated MoS2 nanosheets nucleate vertically from Ag-NPs seeds, enabling the growth of both metallic and semiconductor phases 1T/2H-MoS2. Findings reveal remarkable enhancement of the Raman scattering and an exceptional broadband optical absorption attributed to plasmonic effects induced by the presence of both metallic 1T-MoS2 and Ag-NPS at 2H-MoS2 interfaces. To leverage this effect, photodegradation tests are conducted to remove methyl orange pollutant. Notably, results reveal a significant increase in photodegradation efficiency and rate constant, reaching up to 120% and 550% over pristine 2H-MoS2, respectively. This finding underscores the role of Ag-NPs and 1T-MoS2 tandem to unlock the superior photodegradation properties of vertically aligned 2H-MoS2 toward methyl orange, paving the way for the development of dichalcogenide-based hybrid photocatalyst for wastewater treatment and environmental remediation.
Open Access
Flat lens antenna using gap waveguide technology at millimeter waves
(IEEE, 2021) Pérez Quintana, Dayan; Bilitos, Christos; Ruiz-García, Jorge; González-Ovejero, David; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
In this paper, a flat lens antenna using Gap Waveguide (GW) technology working in the millimeter waves band was designed. The metamaterial lens is fed using a Groove Gap Waveguide (GGW) horn antenna in order to achieve a plane wavefront at broadside. Both devices, metalens and GGW antenna achieve excellent radiation results when combined together. Due to metallic composition, the structure presents more robustness, low loss, and adaptability to a flat surface, able to be used in millimeter wave application.
Open Access
Nanoparticle derived suppressed-scattering bands for radiative cooling
(IEEE, 2023) Lezaun Capdevila, Carlos; Pérez Escudero, José Manuel; Torres García, Alicia E.; Caggiano, Antonio; Peralta, Ignacio; Dolado, Jorge S.; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Light scattering using resonant nanoparticles is crucial for improving sun irradiance reflection in a daytime radiative cooler. Popular nanoparticles in radiative cooling literature are analyzed in terms of scattering performance due to material dispersion. Different scattering properties in the infrared range have been detected while a similar behavior can be achieved in the solar range due to changes in material dispersion. Also, suppressed scattering windows are produced by dispersive nanoparticles, allowing high reflectance while enabling thermal emission selectively. Material dispersion alone produces such scattering windows, thus, given a material, they will always remain in the same region regardless geometry and location of particles. Lastly, calcium silicate hydrate (CSH), the main phase of concrete, is studied as a dispersive host example. These results demonstrate the importance of a co-design between host and nanoparticles dispersion for daytime radiative cooling and that nanoporosities design are a key ingredient that could allow concrete-based daytime radiative coolers.
Open Access
Enhancing the infrared and visible emission properties of calcium silicate hydrate for radiative cooling using metamaterials
(IEEE, 2022) Lezaun Capdevila, Carlos; Dolado, Jorge S.; Torres García, Alicia E.; Pérez Escudero, José Manuel; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
Two periodic structures composed of metal cylinders with different orientations are used to improve the solar reflection of calcium silicate hydrate (CSH) while maintaining its atmospheric emission. Interesting effects have been found when the distance between bars is small, suggesting that lattice effects, arising from the interaction between the rods could be leveraged in the design of these metamaterials. The size of the metal bars is selected based on state of the art micro-manufacturing techniques. This study limits its scope to a CSH gel model; i.e. the most important component of cement-based materials. Further research will be undertaken to consider a best description of the dielectric function of concrete.
Open Access
Lithography-free perfect narrowband absorbers using simple layered structures
(IEEE, 2024-10-08) Lezaun Capdevila, Carlos; Navajas Hernández, David; Liberal Olleta, Íñigo; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Light absorbers are key components for multiple applications ranging from heat and energy management to communications and sensing. This work explores different complex permittivity combinations for material-reflector and material-spacer-reflector configurations, achieving perfect absorption under different permittivity regimes and thicknesses. Using silicon carbide, we discuss polarization and angle dependencies, and the potential of exploiting different permittivity regimes within a device for multi-band absorption. This work helps standardize absorber design and offer insights to engineer perfect absorbers for applications such as thermal emission, absorption, communication and sensing.
Open Access
Evolutionary algorithms applied to multi-layered radiative cooling metamaterials
(IEEE, 2022) Lezaun Capdevila, Carlos; Jorajuria Gómez, Tania; Torres García, Alicia E.; Herrera, Pilar; Beruete Díaz, Miguel; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A newly design method for designing multi-layered radiative cooling metamaterials based on genetic algorithms (GAs) is exposed. The developed GA has been tested in three cases, resulting in three different structures that achieve, theoretically under direct sunlight, a net cooling power of 39.96 W/m 2 , 57.78 W/m 2 and 61.77 W/m 2 . Such devices are composed of 9, 15 and 24 layers respectively with a total thickness of less than 4.8 µm in the worst case. By the nature of the method, fewer design experience in metamaterials is needed, as well as it is free-cost, due to the use of analytical calculations for the emissivity of the meta materials instead of a commercial generic electromagnetic solver. Automated design of radiative cooling multi-layered structures and other applications in the infrared range can be further developed with this work.