Open Access
Micro sized interdigital capacitor for humidity detection based on agarose coating
(2021) Vitoria Pascual, Ignacio; Armas, Dayron; Coronel Camones, Carlos Manuel; Ozcariz Celaya, Aritz; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A micro sized interdigital capacitor has been proposed for the detection of relative humidity. The photolithography technique enables the fabrication of fingers with a size of 10x500 um. A thin film of agarose functionalizes the sensor for humidity sensing, which improves its performance by 155 times, obtaining a sensitivity of 32.98 pF/%RH.
Open Access
Bloch surface wave resonances generated with dielectric stack of high refractive index contrast deposited on a D-shaped optical fiber for sensing applications
(Optica Publishing Group, 2022) Del Villar, Ignacio; Kwietniewski, Norbert; González-Valencia, Esteban; Burnat, Dariusz; Armas, Dayron; Pitula, Emil; Matías Maestro, Ignacio; Chiavaioli, Francesco; Torres, Pedro; Smietana, Mateusz; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
A 5-layer stack composed of TiO2 and Al2O3, two materials with a high refractive index contrast, was deposited on a D-shaped fiber to generate Bloch surface wave resonances with an improved figure of merit.
Open Access
Ammonia gas optical sensor based on lossy mode resonances
(IEEE, 2023) Armas, Dayron; Zubiate Orzanco, Pablo; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This letter presents the fabrication and characterization of an ammonia (NH 3) gas optical sensor based on lossy mode resonances (LMRs). A chromium (III) oxide (Cr 2 O 3) thin film deposited onto a planar waveguide was used as LMR supporting coating. The obtained LMR shows a maximum attenuation wavelength or resonance wavelength centered at 673 nm. The optical properties of the coating can be modified as a function of the presence and concentration of NH 3 in the external medium. Consequently, the refractive index of the Cr 2 O 3 thin film will change, producing a red-shift of the resonance wavelength. Obtained devices were tested for different concentrations of NH 3 as well as repetitive cycles. Concentrations as low as 10 ppbv of NH 3 were detected at room temperature. Machine learning regression models were used to mitigate the cross-sensitivity of the device under temperature and humidity fluctuations.
Open Access
Nano-photonic crystal D-shaped fiber devices for label-free biosensing at the attomolar limit of detection
(Wiley, 2024-07-23) Del Villar, Ignacio; González-Valencia, Esteban; Kwietniewski, Norbert; Burnat, Dariusz; Armas, Dayron; Pitula, Emil; Janik, Monika; Matías Maestro, Ignacio; Giannetti, Ambra; Torres, Pedro; Chiavaioli, Francesco; Smietana, Mateusz; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Maintaining both high sensitivity and large figure of merit (FoM) is crucial in regard to the performance of optical devices, particularly when they are intended for use as biosensors with extremely low limit of detection (LoD). Here, a stack of nano-assembled layers in the form of 1D photonic crystal, deposited on D-shaped single-mode fibers, is created to meet these criteria, resulting in the generation of Bloch surface wave resonances. The increase in the contrast between high and low refractive index (RI) nano-layers, along with the reduction of losses, enables not only to achieve high sensitivity, but also a narrowed resonance bandwidth, leading to a significant enhancement in the FoM. Preliminary testing for bulk RI sensitivity is carried out, and the effect of an additional nano-layer that mimics a biological layer where binding interactions occur is also considered. Finally, the biosensing capability is assessed by detecting immunoglobulin G in serum at very low concentrations, and a record LoD of 70 aM is achieved. An optical fiber biosensor that is capable of attaining extraordinarily low LoD in the attomolar range is not only a remarkable technical outcome, but can also be envisaged as a powerful tool for early diagnosis of diseases.
Open Access
Enhancement of lossy mode resonance sensing properties by the introduction of an intermediate low-refractive-index layer
(Optica, 2023) Armas, Dayron; Kwietniewski, Norbert; Matías Maestro, Ignacio; Burnat, Dariusz; Smietana, Mateusz; Del Villar, Ignacio; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Devices based on the lossy mode resonance (LMR) effect have found numerous sensing applications. Herein, the enhancement of the sensing properties by the introduction of an intermediate layer between the substrate and the LMR-supporting film is discussed. Experimental results for a silicon oxide (SiO2) layer of tuned thickness between a glass slide substrate and a thin film of titanium oxide (TiO2) prove the possibility of significantly increasing the LMR depth and the figure of merit (FoM) for refractive index sensing applications, which is supported by a numerical analysis using the plane wave method for a one-dimensional multilayer waveguide. The application of the intermediate layer allows the introduction of a new, to the best of our knowledge, degree of freedom into the design of LMR-based sensors, resulting in improved performance for demanding fields such as chemical sensing or biosensing.
Open Access
Micro sized interdigital capacitor for gases detection based on graphene oxide coating
(Springer, 2023) Vitoria Pascual, Ignacio; Armas, Dayron; Coronel Camones, Carlos Manuel; Algarra González, Manuel; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Mukhopadhyay, Subhas C.; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
A micro sized interdigital capacitor sensible to CO2 and NO is studied in this work. The photolithography technique enables to obtain fingers with dimensions of 10 × 500 µm and separated 7 µm between them. The deposition of a film composed of graphene oxide particles as the dielectrics of the capacitor allows to measure the gas concentration of CO2 and NO mixed with N2. The sensors were characterized in a gas chamber with a constant flow, obtaining promising results in changes of capacitance at 100 Hz. The sensors have a good linearity and sensitivity with a R2 = 0.996 and 5.026·10-1 pF/ % v/v for CO2 and R2=0.972 and 1.433·10-1 pF/ppb for NO.
Open Access
Generation of lossy mode resonances (LMR) using perovskite nanofilms
(Chinese Academy of Sciences, 2024) Armas, Dayron; Matías Maestro, Ignacio; López-González, M. Carmen; Ruiz Zamarreño, Carlos; Zubiate Orzanco, Pablo; Del Villar, Ignacio; Romero, Beatriz; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
The results presented here show for the first time the experimental demonstration of the fabrication of lossy mode resonance (LMR) devices based on perovskite coatings deposited on planar waveguides. Perovskite thin films have been obtained by means of the spin coating technique and their presence was confirmed by ellipsometry, scanning electron microscopy, and X-ray diffraction testing. The LMRs can be generated in a wide wavelength range and the experimental results agree with the theoretical simulations. Overall, this study highlights the potential of perovskite thin films for the development of novel LMR-based devices that can be used for environmental monitoring, industrial sensing, and gas detection, among other applications.