Posibles nuevas vías de investigación en teoría de la comunicación a través de modelos matemáticos: análisis topológico

Uno de los pocos puntos en los que los metodólogos de las ciencias sociales están de acuerdo es el divorcio existente entre trabajo teórico y trabajo metodológico en las prácticas sociales concretas. Por otro lado, para la creación del corpus de las ciencias sociales se ha tropezado secularmente con un grave problema o inconveniente: la carencia o insuficiencia de un «lenguaje común» que permitiera el trabajo interdisciplinario de los diferentes científicos sociales. Por paradójico que parezca, este inconveniente no está siendo solucionado, únicamente, desde dentro de las ciencias sociales, sino que ha sido precisa la colaboración de otras ciencias, especialmente las ciencias exactas (física, matemáticas...). Estos dos aspectos epistemológicos de las ciencias sociales han inducido a buena parte de los investigadores sociales a abordar el estudio y análisis de las prácticas sociales a través de la Teoría de la Comunicación

Wavelength and intensity based lossy mode resonance breathing sensor

Copper oxide (CuO) allows the generation of lossy mode resonance (LMR) in a wide wavelength range of the optical spectrum, both in the visible and the near-infrared (NIR). For this, it is necessary to use a configuration based on the lateral incidence of light on the edge of a planar waveguide structure. On the other hand, the use of additional coatings of tin oxide (SnO2) and agarose allows an increase in the sensitivity of the sensor, in response to the breathing monitoring. The sensors were characterized, both in intensity and wavelength. In both cases their behavior depends on the position of the LMR in the optical spectrum. Therefore, it is convenient to extract the design rules that allow an optimal behavior of the sensor. In this sense, sensors located in the NIR presented a better behavior in terms of sensitivity and quality of the signal. In addition, the devices were tested in different conditions: repetitive tests at different distances, oral and nasal breathing, and breathing after doing physical exercise.The authors would to acknowledge the partial support to the Agencia Estatal de Investigacion (AEI) from the Spanish Ministry of Economy and Competitiveness (PID2019-106231RB-I00 and PID2019-106070RB-I00 research funds) and the predoctoral research grant of the Public University of Navarra

Nanofabrication of phase-shifted Bragg gratings on the end facet of multimode fiber towards development of optical filters and sensors

This work describes the process of nanofabrication of phase-shifted Bragg gratings on the end facet of a multimode optical fiber with a pulsed DC sputtering system based on a single target. Several structures have been explored as a function of parameters such as the number of layers or the phase-shift. The experimental results, corroborated with simulations based on plane-wave propagation in a stack of homogeneous layers, indicate that the phase-shift can be controlled with a high degree of accuracy. The device could be used both in communications, as a filter, or in the sensors domain. As an example of application, a humidity sensor with wavelength shifts of 12 nm in the range of 30 to 90% relative humidity (200 pm/% relative humidity) is presented.This work was supported by the Spanish Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-78047-R)

Vibration detection using optical fiber sensors

Condition monitoring of heavy electromechanical equipment is commonly accomplished in the industry using vibration analysis. Several techniques, mainly based on capacitive and piezoelectric accelerometers, have been applied for predictive maintenance. However, the negative influence of the electromagnetic interference (EMI) can be a real problem when electrical signals are used to detect and transmit physical parameters in noisy environments such as electric power generator plants with high levels of EMI. Optical fiber sensors are increasingly used because of the nonelectrical nature of signals. In this paper, the most frequently used vibration optical fiber sensors will be reviewed, classifying them by the sensing techniques and measurement principles. The main techniques, intensity modulation, fiber bragg gratings and Fabry-P´erot Interferometry, will be reviewed here

Fluorescent sensors for the detection of heavy metal ions in aqueous media

Due to the risks that water contamination implies for human health and environmental protection, monitoring the quality of water is a major concern of the present era. Therefore, in recent years several efforts have been dedicated to the development of fast, sensitive, and selective sensors for the detection of heavy metal ions. In particular, fluorescent sensors have gained in popularity due to their interesting features, such as high specificity, sensitivity, and reversibility. Thus, this review is devoted to the recent advances in fluorescent sensors for the monitoring of these contaminants, and special focus is placed on those devices based on fluorescent aptasensors, quantum dots, and organic dyes.This work was supported by the Spanish State Research Agency (AEI) and the Spanish Ministry of Economy and Competitiveness through the TEC2016-79367-C2-2-R project. Nerea de Acha would also like to acknowledge her pre-doctoral fellowship (reference BES-2014-069692) funded by the Spanish Ministry of Economy and Competitiveness through the TEC2013-43679-R project

Improving the width of lossy mode resonances in a reflection configuration D-shaped fiber by nanocoating laser ablation

The full width at half maximum (FWHM) of lossy mode resonances (LMRs) in the optical spectrum depends on the homogeneity of the thin film deposited. In this Letter, a method for improving the FWHM is applied for an LMR generated by a D-shaped optical fiber in reflection configuration. For this purpose, three samples with different attenuation were deposited with DC sputtering thin films of SnO2−x, and a further controlled immersion of the samples in water was performed. A laser-cleaner method was used to improve the FWHM characteristics of one of the samples from 106 to 53 nm. This improvement can be applied to thin-film-based sensors where there is a problem with the inhomogeneity of the coating thickness. Moreover, with this technique, it was proved that a coated length of just 3–4 mm permits the generation of an LMR, with implications for the miniaturization of the final device.Gobierno de Navarra, Ayuda a Movilidad Internacional 2019; Agencia Estatal de Investigación (TEC2016-79367-C2-2-R.)

Simultaneous generation of surface plasmon and lossy mode resonances in the same planar platform

A planar waveguide consisting of a coverslip for a microscope glass slide was deposited in one of its two faces with two materials: silver and indium tin oxide (ITO). The incidence of light by the edge of the coverslip permitted the generation of both surface plasmon and lossy mode resonances (SPRs and LMRs) in the same transmission spectrum with a single optical source and detector. This proves the ability of this optical platform to be used as a benchmark for comparing different optical phenomena generated by both metal and dielectric materials, which can be used to progress in the assessment of different sensing technologies. Here the SPR and the LMR were compared in terms of sensitivity to refractive index and figure of merit (FoM), at the same time it was demonstrated that both resonances can operate independently when silver and ITO coated regions are surrounded by different refractive index liquids. The results were supported with numerical results that confirm the experimental ones.The authors would like to acknowledge the partial support to the Agencia Estatal de Investigacion (AEI) PID2019-106070RB-I00 and PID2019-106231RB-I00 research funds, and the predoctoral research grants of the Public University of Navarra

Optical fiber vacuum sensor based on etched SMS structure and PDMS coating

In this work, an optical fiber vacuum sensor based on a single-mode multimode single-mode (SMS) structure coated with polydimethylsiloxane (PDMS) is studied. The SMS structure generates an interferometric pattern based on multimode interference. The structure is dip-coated with a layer of PDMS, whose optical properties change when it is subjected to varying vacuum pressure. Different strategies are applied in an attempt to improve the final performance of the sensor, such as decreasing the diameter of the fiber and modifying the properties of the coating by modifying the proportion of solvent. Decreasing the diameter of the optical fiber and using toluene as a solvent are both proved to be successful strategies for increasing the sensitivity of the sensor. The devices are studied in the 1×10-3–10 mbar range with a maximum wavelength shift of 12 nm, leading to a maximum sensitivity of 35 nm/mbar. The simplicity of the fabrication process, which can be applied to more sensitive structures, suggests that PDMS may be a good choice for the development of optical fiber vacuum sensors.This work was supported by the Spanish Agencia Estatal de Investigación (AEI), Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-79367-C2-2-R) and a Torres-Quevedo grant from the Science and Innovation Ministry (PTQ2018-010221)

Optical fiber vacuum sensor based on modal interferometer and PDMS coating

Trabajo presentado a la 18th IEEE Sensors Conference. Montreal, 2019This work studies the behavior of polydimethylsiloxane (PDMS) as a transducer for optical vacuum pressure measurements. The optical structure chosen for this device is a modal interferometer achieved by splicing a coreless multimode optical fiber between two single mode fibers. Then, an etching process is applied to the obtained device, in order to decrease the diameter of the fiber and increase the sensitivity. Finally, the fiber is coated by dip-coating with a layer of PDMS, which changes its volume with pressure changes. The device has been studied in the 1x10(-3) mbar to 10 mbar range with a wavelength shift of 4 nm. A maximum sensitivity of 35 nm/mbar was obtained. The simple fabrication process, which can be applied to more sensitive structures, suggest that PDMS can be a good choice for the development of optical fiber vacuum sensors.This work was supported by Spanish Agencia Estatal de Investigacion (AEI). Fondo Europeo de Desarrollo Regional (FEDER) (TEC2016-79367-C2-2-R and TEC2016-78047-R)

Optical fiber immunosensors optimized with cladding etching and ITO nanodeposition

Etched optical fiber immunosensors, with and without ITO nanodeposition, have been developed. The performance of these immunosensors has been assessed implementing an immunoassay. The sensitivity of the mmnunosensor increased by a factor of 4 with the ITO nanocoating, whereas the limit of the detection in both types of devices was 0.2 mg/L of antigens in solution.This work was supported in part by the Spanish Ministry of Education and Science-FEDER TEC 2016-78047 and by the Government of Navarre through its projects with references: 2017/PI008, 2016/PC025 and 2016/PC026. Besides, was supported in part by the Colombian Administrative Department of Science, Technology and Innovation - Colciencias, through the Program for national doctorates, calling 617 of 2013, and by the project 'Biosensores a fibra optica para la deteccion rapida de enfermedades' supported by the Universidad Nacional de Colombia (Hermes code 40834)