Open Access
Photonic chip breath analyzer
(SpringerOpen, 2025-06-03) Gallego Martínez, Elieser Ernesto; Matías Maestro, Ignacio; Ruiz Zamarreño, Carlos; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This work introduces a novel single-package optical sensing device for multiple gas sensing, which is suitable for breath analysis applications. It is fabricated on a coverslip substrate via a sputtering technique and uses a planar waveguide configuration with lateral incidence of light. It features three sequentially ordered strips of different materials, which serve to increase the multivariate nature of the response of the device to different gases. For the proof-of-concept, the selected materials are indium tin oxide (ITO), tin oxide (SnO2), and chromium oxide III (Cr2O3), while the selected gases are nitric oxide (NO), acetylene (C2H2), and ammonia (NH3). The sensing mechanism is based on the hyperbolic mode resonance (HMR) effect, with the first-order resonance obtained for each strip located in the near infrared region. The multivariate response of the resonances and the correlation with the concentration of each gas allow training a machine learning (ML) model based on a nonlinear autoregressive neural network, enabling the accurate prediction of the concentration of each gas. The obtained limit of detection for all the gases was in the order of a few parts per billion. This innovative approach coined as the multivariate optical resonances spectroscopy demonstrates the potential of HMR-based optical sensors in combination with ML techniques for ultra-sensitive multi-gas detection applications using a single device.
Open Access
Lossy mode resonance based 1-butanol sensor in the mid-infrared region
(Elsevier, 2023-08-01) Gallego Martínez, Elieser Ernesto; Matías Maestro, Ignacio; Melendi Espina, Sonia; Hernáez Sáenz de Zaitigui, Miguel; Ruiz Zamarreño, Carlos; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The utilization of nanometric Graphene Oxide / Polyethyleneimine (GO/PEI) bilayers deposited onto SnO2-coated CaF2 planar waveguides significantly enhances the sensitivity of Lossy Mode Resonances (LMR) based devices for gas sensing applications. LMR generation in the mid-infrared region, which also contributed to achieve better sensitivities, was accomplished with the aid of fluorinated (CaF2) planar waveguides. LMR wavelength shift was studied as a function of the number of GO/PEI bilayers. In the particular case of 10 bilayers of GO/PEI, the sensitivity of the device to 1-butanol was 70.4 pm/ppm, which increased by a factor of 5 compared to the device without GO/PEI bilayers. The GO/PEI sensor was also sensitive to other alcohols, like 2-propanol, but it showed negligible sensitivity to other gases, such as CO2, NH3 or C2H2. The cross sensitivity with temperature was tested at temperatures of 20, 100 and 180 ºC during water vapor measurement (1723 ppm), showing that the sensor performance was not affected by the temperature fluctuations.
Embargo
Hyperbolic mode resonance-based acetone optical sensors powered by ensemble learning
(Elsevier, 2024-11-01) Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Meurs, Joris; Cristescu, Simona M.; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The current work describes and compares the performance of hyperbolic mode resonance (HMR)-based sensors for the detection of acetone at parts per billion (ppb) concentrations using ensemble machine learning (EML) techniques. A pair of HMR based-sensors with resonances located in the visible (VIS) and mid infrared (MIR) regions were obtained in order to train a set of ensemble machine learning models. The response of the detection system formed by both devices in the VIS and MIR regions, with the help of the EML system, allowed the limit of detection (LoD) of the sensors to be reduced by an order of magnitude. It is the first time that HMR-based sensors are shown in practical applications, at the same time that their performance is improved using EML techniques. This opens new avenues for the use of this type of HMR-based sensors for the detection of other substances, in addition to improving the performance of any optoelectronic sensor using EML techniques.
Open Access
LMR-based optical sensor for ethylene detection at visible and mid-infrared regions
(IEEE, 2023) Gallego Martínez, Elieser Ernesto; Hualde Otamendi, Mikel; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ethylene monitoring has long been a method of controlling the ripening of climacteric fruits, but it turns out that this gas is an important biomarker in biomedical applications. This work presents an optical gas sensor based on the lossy mode resonance (LMR) effect for ethylene detection in planar waveguide configuration. Two different approaches have been explored: one in the visible (VIS) spectral region and the second one in the mid infrared (MIR) region. Optical resonances have been achieved, in all cases, by means of sputtered tin oxide thin films. Response and recovery times were 54 and 246 s, respectively, for the sensor with the resonance in the VIS region, while the device operating in the MIR obtained response and recovery times of 19 and 47 s, respectively. The sensitivity during ethylene detection varied from 93.8 to 187.5 pm/ppm with the devices working in the VIS and MIR regions, respectively. According to the calibration curve, devices show an ethylene limit of detection (LOD) of 4.0058 and 0.6532 ppm in the VIS and MIR spectral regions, respectively, which finds applications in climacteric fruit ripening assessment as well as hemodialysis control. Cross sensitivity with humidity was also characterized for both devices.
Embargo
Photoisomerization-induced LMR shift for UV radiation detection
(Elsevier, 2024) Gallego Martínez, Elieser Ernesto; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren
This work presents an optical sensor for ultraviolet radiation (UV) detection, based on the combined effects of Lossy Mode Resonance (LMR) in the mid infrared (MIR) spectral region and the photoisomerization of a polymeric dye coating. LMR was obtained by means of a sputtered SnO2 thin film on a tetrafluoroethylene-perfluoro (or alkoxy Vinyl Ether, PFA) substrate, along with a photo sensitive coating based on poly R-478. Obtained devices shown response and recovery times of 12 and 43 s, respectively, for an UV excitation of 71 mW at 365 nm. Sensitivity as a function of the excitation wavelength was studied with the highest value of 26 nm/mW obtained at 280 nm. For this excitation wavelength, the limit of detection (LoD) obtained was 0.024 mW. Four different excitation wavelengths were used to cover all UV regions (280, 310, 365 and 395 nm). All measurements were performed at room temperature and humidity (25 ¿C ± 1 ¿C and 13% R.H. ± 2% R.H. respectively). As far as we know, it is the first time that the LMR effect has been recognized in combination with a photoisomerization process.
Open Access
Gas sensor based on lossy mode resonances by means of thin graphene oxide films fabricated onto planar coverslips
(MDPI, 2023) Vitoria Pascual, Ignacio; Gallego Martínez, Elieser Ernesto; Melendi Espina, Sonia; Hernáez Sáenz de Zaitigui, Miguel; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The use of planar waveguides has recently shown great success in the field of optical sensors based on the Lossy Mode Resonance (LMR) phenomenon. The properties of Graphene Oxide (GO) have been widely exploited in various sectors of science and technology, with promising results for gas sensing applications. This work combines both, the LMR-based sensing technology on planar waveguides and the use of a GO thin film as a sensitive coating, to monitor ethanol, water, and acetone. Experimental results on the fabrication and performance of the sensor are presented. The obtained results showed a sensitivity of 3.1, 2.0, and 0.6 pm/ppm for ethanol, water, and acetone respectively, with a linearity factor R2 > 0.95 in all cases.