Open Access
A comparative study of two different approaches for the incorporation of silver nanoparticles into layer-by-layer films
(Springer, 2014) Rivero Fuente, Pedro J.; Goicoechea Fernández, Javier; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, a comparative study about the incorporation of silver nanoparticles (AgNPs) into thin films is presented using two alternative methods, the in situ synthesis process and the layer-by-layer embedding deposition technique. The influence of several parameters such as color of the films, thickness evolution, thermal post-treatment, or distribution of the AgNPs along the coatings has been studied. Thermal post-treatment was used to induce the formation of hydrogel-like AgNPs-loaded thin films. Cross-sectional transmission electron microscopy micrographs, atomic force microscopy images, and UV-vis spectra reveal significant differences in the size and distribution of the AgNPs into the films as well as the maximal absorbance and wavelength position of the localized surface plasmon resonance absorption bands before and after thermal post-treatment. This work contributes for
Open Access
Micro and nanostructured materials for the development of optical fibre sensors
(MDPI, 2017) Elosúa Aguado, César; Arregui San Martín, Francisco Javier; Del Villar, Ignacio; Ruiz Zamarreño, Carlos; Corres Sanz, Jesús María; Bariáin Aisa, Cándido; Goicoechea Fernández, Javier; Hernáez Sáenz de Zaitigui, Miguel; Rivero Fuente, Pedro J.; Socorro Leránoz, Abián Bentor; Urrutia Azcona, Aitor; Sánchez Zábal, Pedro; Zubiate Orzanco, Pablo; López Torres, Diego; Acha Morrás, Nerea de; Ascorbe Muruzabal, Joaquín; Ozcariz Celaya, Aritz; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
The measurement of chemical and biomedical parameters can take advantage of the features exclusively offered by optical fibre: passive nature, electromagnetic immunity and chemical stability are some of the most relevant ones. The small dimensions of the fibre generally require that the sensing material be loaded into a supporting matrix whose morphology is adjusted at a nanometric scale. Thanks to the advances in nanotechnology new deposition methods have been developed: they allow reagents from different chemical nature to be embedded into films with a thickness always below a few microns that also show a relevant aspect ratio to ensure a high transduction interface. This review reveals some of the main techniques that are currently been employed to develop this kind of sensors, describing in detail both the resulting supporting matrices as well as the sensing materials used. The main objective is to offer a general view of the state of the art to expose the main challenges and chances that this technology is facing currently.
Open Access
Icephobic coating based on novel SLIPS made of infused PTFE fibers for aerospace application
(MDPI, 2024) Vicente Gómara, Adrián; Rivero Fuente, Pedro J.; Rehfeld, Nadine; Stake, Andreas; García, Paloma; Carreño, Francisco; Mora, Julio; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA1929
The development of slippery surfaces has been widely investigated due to their excellent icephobic properties. A distinct kind of an ice-repellent structure known as a slippery liquid-infused porous surface (SLIPS) has recently drawn attention due to its simplicity and efficacy as a passive ice-protection method. These surfaces are well known for exhibiting very low ice adhesion values (τice < 20 kPa). In this study, pure Polytetrafluoroethylene (PTFE) fibers were fabricated using the electrospinning process to produce superhydrophobic (SHS) porous coatings on samples of the aeronautical alloy AA6061-T6. Due to the high fluorine–carbon bond strength, PTFE shows high resistance and chemical inertness to almost all corrosive reagents as well as extreme hydrophobicity and high thermal stability. However, these unique properties make PTFE difficult to process. For this reason, to develop PTFE fibers, the electrospinning technique has been used by an PTFE nanoparticles (nP PTFE) dispersion with addition of a very small amount of polyethylene oxide (PEO) followed with a sintering process (380 °C for 10 min) to melt the nP PTFE together and form uniform fibers. Once the porous matrix of PTFE fibers is attached, lubricating oil is added into the micro/nanoscale structure in the SHS in place of air to create a SLIPS. The experimental results show a high-water contact angle (WCA) ≈ 150° and low roll-off angle (αroll-off) ≈ 22° for SHS porous coating and a decrease in the WCA ≈ 100° and a very low αroll-off ≈ 15° for SLIPS coating. On one hand, ice adhesion centrifuge tests were conducted for two types of icing conditions (glaze and rime) accreted in an ice wind tunnel (IWT), as well as static ice at different ice adhesion centrifuge test facilities in order to compare the results for SHS, SLIPs and reference materials. This is considered a preliminary step in standardization efforts where similar performance are obtained. On the other hand, the ice adhesion results show 65 kPa in the case of SHS and 4.2 kPa of SLIPS for static ice and <10 kPa for rime and glace ice. These results imply a significant improvement in this type of coatings due to the combined effect of fibers PTFE and silicon oil lubricant.
Open Access
An alternative methodology for the evaluation of photocatalytic activity of polymeric coatings by monitoring dye degradation
(MDPI, 2022) Sandúa Fernández, Xabier; Rivero Fuente, Pedro J.; Esparza Gorráiz, Joseba; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work provides an alternative method for evaluating the photodegradation behaviour of different types of dyes such as Methylene Blue, Rhodamine B, Congo Red, Metanil Yellow, and Malachite Green. In this methodology, the coating is dyed with the chosen colorant and two beams of light are combined and channelled to a spot on the dyed coating through an optical fibre, the first one from an ultraviolet (UV) source (which is the responsible of activating photocatalysis) and the second one from a Visible light source, which is employed to monitor changes in colour along the time. The photocatalytic coating selected for testing this methodology consists of a mat of electrospun poly (acrylic acid) (PAA) fibres that acts as base film, furtherly coated by using layer-by-layer (LbL) assembly technique for the immobilization of two different photocatalytic metal oxide precursors (TiO2 and Fe2O3) nanoparticles. The morphological characterization of the samples has been implemented by means of scanning electron microscopy (SEM), confocal microscopy, and water contact angle measurements in order to analyse the resultant thickness, roughness, electrospun fibre diameter, and wettability. The experimental results clearly demonstrate the validity of the methodology to measure the photocatalytic activity in all dyed coatings, although significant differences have been observed depending on the selected dye.
Open Access
Effect of the temperature in the mechanical properties of austenite, ferrite and sigma phases of duplex stainless steels using hardness, microhardness and nanoindentation techniques
(MDPI, 2017) Argandoña Salinas, Gorka; Berlanga Labari, Carlos; Biezma Moraleda, María Victoria; Rivero Fuente, Pedro J.; Peña, Julio; Rodríguez Trías, Rafael; Mekanika, Energetika eta Materialen Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería Mecánica, Energética y de Materiales
The aim of this work is to study the hardness of the ferrite, austenite and sigma phases of a UNS S32760 superduplex stainless steel submitted to different thermal treatments, thus leading to different percentages of the mentioned phases. A comparative study has been performed in order to evaluate the resulting mechanical properties of these phases by using hardness, microhardness and nanoindentation techniques. In addition, optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been also used to identify their presence and distribution. Finally, the experimental results have shown that the resulting hardness values were increased as a function of a longer heat treatment duration which it is associated to the formation of a higher percentage of the sigma phase. However, nanoindentation hardness measurements of this sigma phase showed lower values than expected, being a combination of two main factors, namely the complexity of the sigma phase structure as well as the surface finish (roughness).
Open Access
Corrosion behavior of additively manufactured steels: a comprehensive review
(Wiley, 2025-03-21) Villabona Gorri, Eneko; Veiga Suárez, Fernando; Rivero Fuente, Pedro J.; Uralde Jiménez, Virginia; Suárez, Alfredo; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Additive manufacturing (AM) is transforming the production of steel components, offering unique advantages such as design freedom and the ability to create complex geometries. This review examines the corrosion behavior of various steel types, including austenitic stainless steels (SS), martensitic SS, duplex SS, low-alloy steels, and maraging steels, produced through AM technologies. In addition, the topic of material hybridization through AM is addressed, which allows for the optimization of the properties of the base materials. While AM often generates finer grain structures, particularly in SS, which enhances corrosion resistance, it can also lead to undesirable phases, precipitates, or defects like porosity that degrade performance. Controlling AM process parameters is crucial to achieving the desired microstructure and optimizing corrosion resistance. The review highlights current knowledge, identifies challenges, and underscores the importance of standardized testing methodologies to enable better cross-study comparisons and guide future advancements in corrosion-resistant AM steels.
Open Access
Comparative study of electrospun polydimethylsiloxane fibers as a substitute for fluorine-based polymeric coatings for hydrophobic and icephobic applications
(MDPI, 2024-11-30) Vicente Gómara, Adrián; Rivero Fuente, Pedro J.; Santos, Cleis; Rehfeld, Nadine; Rodríguez Trías, Rafael; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Univertsitate Publikoa, PJUPNA1929
The development of superhydrophobic, waterproof, and breathable membranes, as well as icephobic surfaces, has attracted growing interest. Fluorinated polymers like PTFE or PVDF are highly effective, and previous research by the authors has shown that combining these polymers with electrospinning-induced roughness enhances their hydro- and ice-phobicity. The infusion of these electrospun mats with lubricant oil further improves their icephobic properties, achieving a slippery liquid-infused porous surface (SLIPS). However, their environmental impact has motivated the search for fluorine-free alternatives. This study explores polydimethylsiloxane (PDMS) as an ideal candidate because of its intrinsic properties, such as low surface energy and high flexibility, even at very low temperatures. While some published results have considered this polymer for icephobic applications, in this work, the electrospinning technique has been used for the first time for the fabrication of 95% pure PDMS fibers to obtain hydrophobic porous coatings as well as breathable and waterproof membranes. Moreover, the properties of PDMS made it difficult to process, but these limitations were overcome by adding a very small amount of polyethylene oxide (PEO) followed by a heat treatment process that provides a mat of uniform fibers. The experimental results for the PDMS porous coating confirm a hydrophobic behavior with a water contact angle (WCA) ≈ 118° and roll-off angle (αroll-off) ≈ 55°. In addition, the permeability properties of the fibrous PDMS membrane show a high transmission rate (WVD) ≈ 51.58 g∙m−2∙d−1, providing breathability and waterproofing. Finally, an ice adhesion centrifuge test showed a low ice adhesion value of 46 kPa. These results highlight the potential of PDMS for effective icephobic and waterproof applications.
Open Access
Corrosion of cast aluminum alloys: a review
(MDPI, 2020-10-16) Berlanga Labari, Carlos; Biezma Moraleda, María Victoria; Rivero Fuente, Pedro J.; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
Research on corrosion resistance of cast aluminum alloys is reviewed in this article. The effect of the main microstructural features of cast aluminum alloys such as secondary dendrite arm spacing (SDAS), eutectic silicon morphology, grain size, macrosegregation, microsegregation, and intermetallic compounds is discussed. Moreover, the corrosion resistance of cast aluminum alloys obtained by modern manufacturing processes such as semi-solid and additive manufacturing are analyzed. Finally, the protective effects provided by different coatings on the aluminum cast alloys—such as anodized, plasma electrolytic oxidation (PEO), and laser—is reviewed. Some conclusions and future guidelines for future works are proposed.
Open Access
Contribution to the development of functional nanostructured coatings based on silver nanoparticles
(2014) Rivero Fuente, Pedro J.; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Esta tesis se centra en la síntesis de nanopartículas de plata (AgNPs) y su posterior incorporación en recubrimientos delgados usando dos métodos alternativos: el proceso de síntesis in situ (ISS) de AgNPs y la técnica de embebido capa a capa (LbL-E) de AgNPs. Un preciso control de varios parámetros tales como la forma, tamaño, estado de agregación o la distribución de las nanopartículas de plata en los recubrimientos tiene una gran influencia en la posición final de la longitud de onda de la resonancia localizada de plasmones superficiales (LSPR). Además, estas películas que incorporan nanopartículas de plata han sido estudiadas para dos aplicaciones diferentes. La primera aplicación es la fabricación de recubrimientos antibacterianos eficientes. La segunda aplicación es la fabricación de un nuevo tipo de sensores de fibra óptica basados en la incorporación de nanopartículas de plata en películas nanoestructuradas, que hace posible obtener y observar dos resonancias ópticas diferentes, (LSPR) y resonancias de modos con pérdidas (LMR), en un mismo dispositivo
Open Access
Structural and functional analysis of polyethylene glycol-coated zein nanoparticles
(Elsevier, 2025-08-20) Calvopiña, Jonathan; Rivero Fuente, Pedro J.; Martínez-Ohárriz, María Cristina; Palacio, José F.; Álvarez Galindo, José Ignacio; Espuelas, Socorro; Irache, Juan M. ; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
The development of nanoparticles for drug delivery purposes is faced to a number of challenges, including the complexity of an adequate physico-chemical characterization, especially when nanoparticles are functionalized. The aim of this work was to evaluate and characterize the structure and properties of zein nanoparticles (approximately 200 nm) functionalized with polyethylene glycol (PEG 35,000) at different PEG-to-zein ratios. The interaction between PEG and zein, attributed to hydrogen bonding between the amide groups of zein and the hydroxyl groups of PEG, was evidenced by FTIR and further confirmed by 2D-COS spectroscopy. DSC and TGA thermograms demonstrated the role of PEG in improving nanoparticle thermal stability, with PEG-coated nanoparticles exhibiting higher decomposition temperatures and increased PEG content with higher PEG-to-zein ratios. SEM and AFM imaging of nanoparticle thin films confirmed that PEG decoration enhanced wettability and reduced the hydrophobicity of bare zein nanoparticles, consistent with Rose Bengal test results. Additionally, AFM analysis of nanoparticle distribution in a mucin thin film demonstrated that PEG coating improved nanoparticle dispersibility within the mucin matrix, in line with previous studies describing the increased diffusivity and mucus-permeation properties of nanoparticles coated with hydrophilic polymers. In summary, this study highlights the importance of an in-depth analysis of the physicochemical characteristics of nanoparticles, providing valuable structural insights that facilitate optimization and the selection of the most suitable compositions for preclinical development.