Person:
Martínez Hernández, María Elena

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Martínez Hernández

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María Elena

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Ingeniería Eléctrica y Electrónica

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0000-0001-6557-9007

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811539

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Now showing 1 - 6 of 6
  • PublicationOpen Access
    Hg2+ optical fiber sensor based on LSPR generated by gold nanoparticles embedded in LBL nano-assembled coatings
    (MDPI, 2019) Martínez Hernández, María Elena; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Mercury is an important contaminant since it is accumulated in the body of living beings, and very small concentrations are very dangerous in the long term. This paper reports the fabrication of a highly sensitive fiber optic sensor using the layer-by-layer nano-assembly technique with gold nanoparticles (AuNPs). The gold nanoparticles were obtained via a water-based synthesis route that use poly acrylic acid (PAA) as stabilizing agent, in the presence of a borane dimethylamine complex (DMAB) as reducing agent, giving PAA-capped AuNPs. The sensing mechanism is based on the alteration of the Localized Surface Plasmon Resonances (LSPR) generated by AuNPs thanks to the strong chemical affinity of metallic mercury towards gold, which lead to amalgam alloys.
  • PublicationOpen 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.
  • PublicationOpen Access
    Addressing the impact of surface roughness on epsilon-near-zero silicon carbide substrates
    (American Chemical Society, 2023) Navajas Hernández, David; Pérez Escudero, José Manuel; Martínez Hernández, María Elena; Goicoechea Fernández, Javier; Liberal Olleta, Íñigo; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
    Epsilon-near-zero (ENZ) media have been very actively investigated due to their unconventional wave phenomena and strengthened nonlinear response. However, the technological impact of ENZ media will be determined by the quality of realistic ENZ materials, including material loss and surface roughness. Here, we provide a comprehensive experimental study of the impact of surface roughness on ENZ substrates. Using silicon carbide (SiC) substrates with artificially induced roughness, we analyze samples whose roughness ranges from a few to hundreds of nanometer size scales. It is concluded that ENZ substrates with roughness in the few nanometer scale are negatively affected by coupling to longitudinal phonons and strong ENZ fields normal to the surface. On the other hand, when the roughness is in the hundreds of nanometers scale, the ENZ band is found to be more robust than dielectric and surface phonon polariton (SPhP) bands.
  • PublicationOpen Access
    An optical fiber sensor for Hg2+ detection based on the LSPR of silver and gold nanoparticles embedded in a polymeric matrix as an effective sensing material
    (MDPI, 2021-07-07) Martínez Hernández, María Elena; Sandúa Fernández, Xabier; Rivero Fuente, Pedro J.; Goicoechea Fernández, Javier; 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, an optical fiber sensor based on the localized surface plasmon resonance (LSPR) phenomenon is presented as a powerful tool for the detection of heavy metals (Hg2+). The resultant sensing film was fabricated using a nanofabrication process, known as layer-by-layer embedding (LbL-E) deposition technique. In this sense, both silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized using a synthetic chemical protocol as a function of a strict control of three main parameters: polyelectrolyte concentration, loading agent, and reducing agent. The use of metallic nanostructures as sensing materials is of great interest because well-located absorption peaks associated with their LSPR are obtained at 420 nm (AgNPs) and 530 nm (AuNPs). Both plasmonic peaks provide a stable real-time reference that can be extracted from the spectral response of the optical fiber sensor, giving a reliable monitoring of the Hg2+ concentration.
  • PublicationOpen Access
    Sensores de fibra óptica basados en películas delgadas con nanopartículas metálicas
    (2022) Martínez Hernández, María Elena; Goicoechea Fernández, Javier; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    El estudio del nanoensamblado de nanopartículas metálicas sobre fibra ópticaha contribuido al desarrollo de sensores con mayor sensibilidad y eficiencia. Las aplicaciones que se pueden obtener en este campo pueden variar en función de ciertos parámetros como el tipo de nanopartícula metálica, ruta de síntesis, set-up o técnica de nanoensamblado. Esta tesis se centra en la síntesis de nanopartículas metálicas de oro (AuNPs) y plata (AgNPs) y su posterior nanoensamblado en películas delgadas usando las técnicas Layer-by-Layer Embedding (LbL-E) y el proceso de In-Situ Synthesis (ISS), para el desarrollo de sensores de fibra óptica. Este trabajo se encuentra dividido en tres bloques,el primero se centra en el uso de la técnica LbL-E para el desarrollo de sensores plasmónicos de fibra óptica para la detección de parámetros químicos. En segundo lugar, la técnica ISS se ha utilizado como alternativa parala fabricación de un nuevo dispositivo sensor de humedad basado en una cavidad interferométrica de Fabry-Perot en puntade una fibra óptica. Por último, se compara los efectos sobre la sensibilidad de los Tilted Fiber Bragg Grating (TFBG) al índice de refracción externo al utilizar ambas técnicas (ISS y LbL-E) para el nanoensamblaje de AuNPs.
  • PublicationOpen Access
    Self-referenced optical fiber sensor based on LSPR generated by gold and silver nanoparticles embedded in layer-by-layer nanostructured coatings
    (MDPI, 2022) Martínez Hernández, María Elena; Goicoechea Fernández, Javier; Rivero Fuente, Pedro J.; Sandúa Fernández, Xabier; 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
    In this work, an optical fiber sensor based on the localized surface plasmon resonance (LSPR) phenomenon has been designed for the detection of two different chemical species (mercury and hydrogen peroxide) by using Layer-by-Layer Embedding (LbL-E) as a nanofabrication technique. In the first step, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) have been synthesized by using a chemical protocol as a function of the strict control of three main parameters, which were polyelectrolyte concentration, a loading agent, and a reducing agent. In the second step, their incorporation into nanometric thin films have been demonstrated as a function of the number of bilayers, which shows two well-located absorption peaks associated to their LSPR in the visible region at 420 nm (AgNPs) and 530 nm (AuNPs). Finally, both plasmonic peaks provide a stable real-time reference measurement, which can be extracted from the spectral response of the optical fiber sensor, which shows a specific sensing mechanism as a function of the analyte of study.