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
Is there a frontier in sensitivity with lossy mode resonance (LMR) based refractometers?
(Nature Publishing Group, 2017) Ozcariz Celaya, Aritz; Ruiz Zamarreño, Carlos; Zubiate Orzanco, Pablo; Arregui San Martín, Francisco Javier; Ingeniaritza Elektrikoa eta Elektronikoa; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Gobierno de Navarra / Nafarroako Gobernua; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
A tin dioxide thin layer has been studied in order to improve the sensitivity of lossy mode resonances (LMR) based sensors. The effects of the thin film thickness and the polarization of light in a SnO2 coated D-shaped single mode optical fiber have been evaluated. The optimization of such parameters in the fabrication of refractometers have led to an unprecedented sensitivity of over one million nanometers per refractive index unit (RIU), which means a sensitivity below 10^(−9) RIU with a pm resolution detector. This achievement is a milestone for the development of new high sensitivity devices and opens the door to new industrial applications, such as gear oil degradation, or biomedical devices where previous devices could not provide enough sensitivity.
Open Access
D-shape optical fiber pH sensor based on lossy mode resonances (LMRs)
(IEEE, 2016-01-07) Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza
The fabrication and characterization of an optical fiber pH sensor based on Lossy Mode Resonances (LMRs) is presented. PAH/PAA polymeric thin-films fabricated onto side-polished D-shaped optical fibers are used as LMR supporting coatings. The thickness of PAH/PAA coatings can be modified as a function of the external medium pH. As a consequence of this variation, the effective refractive index of the structure will change, producing a shift of the LMR. The fabricated sensor has been used to measure pH from 4.0 to 5.0. This pH sensor showed a sensitivity of 101.3 nm per pH unit, which means a resolution of ~6×10-4 pH units by using a conventional communications Optical Spectrum Analyzer (OSA), which is an improvement over commercial pH sensors.
Open Access
Fiber-based early diagnosis of venous thromboembolic disease by label-free D-dimer detection
(Elsevier, 2019) Zubiate Orzanco, Pablo; Urrutia Azcona, Aitor; Ruiz Zamarreño, Carlos; Egea Urra, Josune; Fernández Irigoyen, Joaquín; Giannetti, Ambra; Baldini, Francesco; Díaz Lucas, Silvia; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Santamaría Martínez, Enrique; Chiavaioli, Francesco; Del Villar, Ignacio; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Institute of Smart Cities - ISC; Ingeniería Eléctrica, Electrónica y de Comunicación; Gobierno de Navarra / Nafarroako Gobernua
D-dimer is a useful diagnostic biomarker for deep vein thrombosis or pulmonary embolism, collectively referred to as venous thromboembolism (VTE). The ability to detect in real-time the amount of D-dimer with a fast and reliable method is a key step to anticipate the appearance of these diseases. Here, the results of a highly specific and sensitive biosensor for the detection of D-dimer based on lossy mode resonance in fiber optics are presented. The unique features of specialty fibers in light management integrated with microfluidics allow detecting D-dimer in human serum with a detection limit of 100 ng/mL, a value 5-fold below the clinical cutoff value. Comparison of the results achieved with mass-spectrometry-based proteomics, which allows for the identification of beta- and gamma-chains of fibrinogen, demonstrates the ability of our platform to specifically (>90%) recognize D-dimer. Therefore, this technology potentially represents a paradigm shift in the development of a simple, high-specificity and label-free biosensing platform, which can be applied to speed up diagnostic healthcare processes of venous thromboembolism toward an early diagnostic and personalized treatment system.
Open Access
High sensitive and selective C-reactive protein detection by means of lossy mode resonance based optical fiber devices
(Elsevier, 2017) Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Sánchez Zábal, Pedro; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work presents the development of high sensitive, selective, fast and reusable C-reactive protein (CRP) aptasensors. This novel approach takes advantage of the utilization of high sensitive refractometers based on Lossy Mode Resonances generated by thin indium tin oxide (ITO) films fabricated onto the planar region of D-shaped optical fibers. CRP selectivity is obtained by means of the adhesion of a CRP specific aptamer chain onto the ITO film using the Layer-by-Layer (LbL) nano-assembly fabrication process. The sensing mechanism relies on resonance wavelength shifts originated by refractive index variations of the aptamer chain in presence of the target molecule. Fabricated devices show high selectivity to CRP when compared with other target molecules, such as urea or creatinine, while maintaining a low detection limit (0.0625 mg/L) and fast response time (61 s). Additionally, these sensors show a repetitive response for several days and are reusable after a cleaning process in ultrapure water.
Open Access
Fiber-optic pH sensors fabrication based on selective deposition of neutral red
(IEEE, 2009-01-22) Hernáez Sáenz de Zaitigui, Miguel; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ruiz Zamarreño, Carlos; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
In this work, a novel application of the electric field directed layer-by-layer self assembly (EFDLA) selective deposition method for the fabrication of optical fiber pH sensors is presented. Here, indium tin oxide (ITO) coated optical fibers have been fabricated via a dip-coating deposition method. These fibers are used as electrodes in the EFDLA protocol in order to deposit selectively the sensitive layer. Neutral Red (NR) colorimetric pH sensitive indicator and the polymers poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) are used in order to obtain a pH sensitive nanostructured coating onto ITO coated optical fibers. The results obtained in this work revealed that the LbL material adsorption on the electrodes can be enhanced or even inhibited when applying a specific direct current voltage between them under some other specific fabrication parameters. Particularly, the response of these sensors to variations of the pH in the surrounding medium was studied when the pH of the solutions used for the fabrication of the films was adjusted to 7.0 and the potential applied between electrodes was set to 2.5 V. These sensors showed fast response time and high repeatability.
Open Access
Resonances in coated long period fiber gratings and cladding removed multimode optical fibers: a comparative study
(Optical Society of America, 2010) Del Villar, Ignacio; Ruiz Zamarreño, Carlos; Hernáez Sáenz de Zaitigui, Miguel; Arregui San Martín, Francisco Javier; Matías Maestro, Ignacio; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Two optical fiber devices have been coated in parallel: a long period fiber grating (LPFG) and a cladding-removed multimode optical fiber (CRMOF). The progressive coating of the LPFG by means of the layer-by-layer electrostatic-self-assembly, permits to observe a resonance wavelength shift of the attenuation bands in the transmission spectrum. The cause of this wavelength shift is the reorganization of the cladding mode effective indices. The cause of this modal reorganization can be understood with the results observed in the CRMOF coated in parallel. A lossy-moderesonance (LMR) is generated in the same wavelength range of the LPFG attenuation bands analyzed. Moreover, the thickness range where the wavelength shift of the LPFG attenuation bands occurs coincides exactly with the thickness range where the LMR can be visualized in the transmission spectrum. These phenomena are analyzed theoretically and corroborated experimentally. The advantages and disadvantages of both optical fiber devices are explained.
Open Access
Experimental demonstration of lossy mode resonance generation for transverse-magnetic and transverse-electric polarizations
(Optica Publishing Group, 2013) Ruiz Zamarreño, Carlos; Zubiate Orzanco, Pablo; Sagüés García, Mikel; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This Letter, presents the fabrication of lossy mode resonance (LMR) devices based on titanium dioxide (TiO2)/ poly(sodium 4-styrenesulfonate) (PSS) coatings deposited on side-polished D-shaped optical fibers. TiO2 thin films have been obtained by means of the layer-by-layer (LbL) self-assembly technique. LbL enables us to produce smooth and homogeneous coatings on the polished side of the fiber. This permits us to couple light from the waveguide to the TiO2-coating/external medium region at specific wavelength ranges. The generation of LMRs depends on the coating thickness, so that thicker coatings can produce more resonances. LMRs are sensitive to the external medium refractive index, which allows its utilization as refractometers. The characteristic D-shaped architecture of the devices employed in this Letter enables us to distinguish TE and TM polarizations, which had not been possible before with regular optical fibers due to their cylindrical symmetry. The results presented here show for the first time the experimental demonstration of the generation of LMRs produced by both TM and TE polarizations. More specifically, for these TiO2/PSS thin films, the TM and TM modes of the LMRs show a wavelength shift of 226 nm for the first-order LMR and 56 nm for the second-order LMR.
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
A comprehensive review of optical fiber refractometers: toward a standard comparative criterion
(Wiley, 2019) Urrutia Azcona, Aitor; Del Villar, Ignacio; Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Thanks to the peculiarities of optical fiber and its ability to be combined with nanotechnology, precise and accurate measurements of the changes in optical properties (i.e., refractive index) of the medium surrounding the fiber are becoming possible with a high degree of performance. Thus, optical fiber sensors (OFSs) are increasingly finding applications in biochemistry and biomedicine. Here, all types of optical fiber refractometers are covered, and they are classified into three main groups: interferometers, grating-based structures, and resonance-based structures (the resonance is induced by coating the optical fiber sensor with a thin film). The performance of these different structures is compared by means of the most common parameters: sensitivity, full width at half minimum or maximum, figure of merit, and quality factor. The aim here is to provide a reliable and easy-to-use tool to compare the performance of the most recent developments on fiber optic refractometers.