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
An antibacterial submicron fiber mat with in situ synthesized silver nanoparticles
(Wiley, 2012) Rivero Fuente, Pedro J.; Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Rodríguez, Yoany; Corres Sanz, Jesús María; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
This work presents an alternative approachfor fabricating electrospun submicron highly hydrophilicfiber mats loaded with silver nanoparticles. These fiber matsshow a high efficient antibacterial behavior, very attractivefor applications like wound healing and skin regenerationprocesses. The fabrication method is divided in two steps.First, poly(acrylic acid) (PAA) and b-cyclodextrin (b-CD)submicron fibers were electrospun and further stabilizedusing a thermal treatment, yielding stable hydrogel-likefibers with diameters ranging from 100 nm up to severalmicrons. In the second step, silver ions were loaded into thefibers and then reduced to silver nanoparticles in-situ. Theelectrospinning parameters were adjusted to achieve thedesired properties of the fiber mat (density, size) and after-wards, the characteristics of the silver nanoparticles(amount, size, aggregation) were tuned by controlling thesilver ion loading mechanism. Highly biocide surfaces wereachieved showing more than 99.99% of killing efficiency.The two-step process improves the reproducibility and tun-ability of the fiber mats. To our knowledge, this is the firsttime that stable hydrogel fibers with a highly biocide behav-ior have been fabricated using electrospinning.
Open Access
Electrospun nanofiber mats for evanescent optical fiber sensors
(Elsevier, 2013) Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Rivero Fuente, Pedro J.; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work, a study about the optical response of electrospun nanofiber (ENF) coatings for their use in evanescent optical fiber sensors is presented. Several types of ENF mats composed of poly(acrylic acid) (PAA) were developed with different ENF diameters and densities. These ENF mats were deposited onto an optical fiber core in order to fabricate humidity evanescent optical fiber sensors. The devices were exposed to relative humidity (RH) variations from 30% RH to 95%RH. The transfer functions of the devices (transmitted optical power versus relative humidity) presented two well-differenced behaviors depending on the ENF diameter and the ENF mat density. The devices with lower ENF diameters and higher mat density showed an increase in the transmitted optical power when RH increased. On the contrary, the devices with higher ENF diameters and lower mat density showed a decrease in the transmitted optical power when RH increased. In addition to this, sensors with thinner ENF overlays, showed a higher sensitivity. In order to study the response time of these devices, the ENFs sensors were submitted to human breathing cycles and presented a response time around 340 ms (exhalation). In spite of the high RH conditions of this experiment, the devices showed a recovery time around 210 ms and a negligible hysteresis or drift with respect to the initial condition (inhalation).
Open Access
Optical sensors based on lossy-mode resonances
(Elsevier Science, 2017) Matías Maestro, Ignacio; Ascorbe Muruzabal, Joaquín; Acha Morrás, Nerea de; López Torres, Diego; Zubiate Orzanco, Pablo; Sánchez Zábal, Pedro; Urrutia Azcona, Aitor; Socorro Leránoz, Abián Bentor; Rivero Fuente, Pedro J.; Hernáez Sáenz de Zaitigui, Miguel; Elosúa Aguado, César; Goicoechea Fernández, Javier; Bariáin Aisa, Cándido; Corres Sanz, Jesús María; Ruiz Zamarreño, Carlos; Arregui San Martín, Francisco Javier; Del Villar, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC
Open Access
Humidity sensor based on a long-period fiber grating coated with a hydrophobic thin film
(2010) Urrutia Azcona, Aitor; Rivero Fuente, Pedro J.; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica
In this work it is proposed a novel fiber optic humidity sensor based on a functionally coated long-period fiber grating (LPG). The coating is composed of tetraorthosilicate matrix functionalized with perfluorooctyltriethoxysilane and its fabrication was performed by the sol-gel technique using a dip coating process using the LPG as substrate. This technique allows to fabricate sensitive films in a fast and simple way compared to other overlay fabrication techniques. The fabricated sensor was tested in a programmable temperature and climatic chamber. Relative humidity (RH) was varied in range from 20%RH to 80%RH at room temperature. The results showed a smooth exponential-like wavelength shift of the LPG attenuation band.
Open Access
Humidity sensor based on silver nanopartlcles embedded in a polymeric coating
(Sciendo, 2012) Rivero Fuente, Pedro J.; Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería; Ingeniaritza; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
In this work, it is presented a novel optical fiber humidity sensor based on silver nanoparticle-loaded polymeric coatings built onto an optical fiber core. The polymeric film was fabricated using the Layer-by-Layer assembly technique. The silver nanoparticles (Ag NPs) were characterized using transmission electron microscopy (TEM and UV-VIS spectroscopy. A Localized Surface Plasmon Resonance (LSPR) attenuation band is observed when the thickness of the coating increases, and showed a very good sensitivity to Relative Humidity (RH) variations, suitable for high performance applications such as human breathing monitoring.
Open Access
Optical fiber sensors based on gold nanorods embedded in polymeric thin films
(Elsevier, 2018) Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Rivero Fuente, Pedro J.; Pildain Lería, Ander; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Ingeniería; Ingeniaritza; Institute for Advanced Materials and Mathematics - INAMAT2
In this work, we present a study about the generation and analysis of optical resonances caused by gold nanorods (GNRs) embedded in films. GNRs were embedded in polymeric thin films using the Layerby-Layer nanoassembly (LbL) deposition technique. Polymer/GNRs thin films of different thicknesses were deposited on the surface of cladding removed optical fibers for sensing. The spectral responses of the optical fiber sensors were monitored during the build-up of the thin films. The generation of two Localized Surface Plasmon Resonances (LSPRs) associated to the GNRs was observed in thinner coatings. These devices with around 12 polymer/GNRs bilayers were characterized as refractometers, providing an intensity-based sensitivity up to 75.69 dB/RIU. For thicker polymer/GNRs overlays, both LSPRs bands were also generated and, additionally, it was observed a new Lossy Mode Resonance (LMR) band due to modes coupled to the sensitive coating. The dependence of these three resonance bands with the surrounding refractive index was studied. Finally, these sensors were tested in a climatic chamber in the 20-90% relative humidity (RH) range and the LMR showed a good sensitivity to RH changes while the LSPR bands remained very stable in comparison. Results showed an excellent sensitivity of 11.2 nm/%RH for the LMR, confirming the potential of this type of optical fiber sensor based on the combination of LSPRs and LMRs bands.
Open Access
An antibacterial surface coating composed of PAH/SiO2 nanostructurated films by Layer by Layer
(2009) Urrutia Azcona, Aitor; Rivero Fuente, Pedro J.; Ruete Ibarrola, Leyre; Goicoechea Fernández, Javier; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Gobierno de Navarra / Nafarroako Gobernua
In this article we propose a novel antibacterial coating composed of SiO2 and the polymer Poly(allylamine hydrochloride) (PAH) on glass slides by the technique Layer-by- Layer (LbL)1. This technique has already used in previous works, and it has the advantage that it allows to control the construction of nanosized and well organized multilayer films. In this work, the new nanotexturized LbL SiO2 surface acts as antibacterial agent. The fabricated coatings have been tested in bacterial cultures of genus Lactobacillus to observe their antibacterial properties.
Open Access
Nanomaterials for functional textiles and fibers
(Springer US, 2015) Rivero Fuente, Pedro J.; Urrutia Azcona, Aitor; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Ingeniería Mecánica, Energética y de Materiales; Mekanika, Energetika eta Materialen Ingeniaritza; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Nanoparticles are very interesting because of their surface properties, different from bulk materials. Such properties make possible to endow ordinary products with new functionalities. Their relatively low cost with respect to other nano-additives make them a promising choice for industrial mass-production systems. Nanoparticles of different kind of materials such as silver, titania, and zinc oxide have been used in the functionalization of fibers and fabrics achieving significantly improved products with new macroscopic properties. This article reviews the most relevant approaches for incorporating such nanoparticles into synthetic fibers used traditionally in the textile industry allowing to give a solution to traditional problems for textiles such as the microorganism growth onto fibers, flammability, robustness against ultraviolet radiation, and many others. In addition, the incorporation of such nanoparticles into special ultrathin fibers is also analyzed. In this field, electrospinning is a very promising technique that allows the fabrication of ultrathin fiber mats with an extraordinary control of their structure and properties, being an ideal alternative for applications such as wound healing or even functional membranes.
Open Access
In situ synthesis of gold nanoparticles in layer-b y-layer polymeric coatings for the fabrication of optical fiber sensors
(MDPI, 2022) Martínez Hernández, María Elena; Goicoechea Fernández, Javier; Rivero Fuente, Pedro J.; Arregui San Martín, Francisco Javier; Ingeniaritza; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Institute for Advanced Materials and Mathematics - INAMAT2; Ingeniería; Ingeniería Eléctrica, Electrónica y de Comunicación
A new method is proposed to tune the interferometric response of wavelength-based optical fiber sensors. Using the nanoparticle in situ synthesis (ISS) technique, it is possible to synthesize gold nanoparticles (AuNPs) within a pre-existing polymeric thin film deposited at the end-face of an optical fiber. This post-process technique allows us to adjust the optical response of the device. The effect of the progressive synthesis of AuNPs upon polymeric film contributed to a remarkable optical contrast enhancement and a very high tuning capability of the reflection spectra in the visible and near-infrared region. The spectral response of the sensor to relative humidity (RH) variations was studied as a proof of concept. These results suggest that the ISS technique can be a useful tool for fiber optic sensor manufacturing.