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
Optical biosensors: a quick overview
(2021) Imas González, José Javier; 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 aims to provide a brief overview of the latest trends in the domain of optical biosensors.
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.
Embargo
Experimental study of sensing performance using hyperbolic mode resonances
(Elsevier, 2025-01-01) Matías Maestro, Ignacio; Del Villar, Ignacio; Corres Sanz, Jesús María; González Salgueiro, Lázaro José; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Surface plasmon resonance (SPR) and lossy mode resonance (LMR) are prominent sensing mechanisms utilized across various fields. The Kretschmann configuration is commonly employed for SPR, while LMR is favored in planar waveguides or optical fibers due to high incidence angles. Recently, hyperbolic mode resonance (HMR) has emerged as a hybrid approach, combining metallic and dielectric thin films. This study explores the impact of incidence angle on HMR using the Kretschmann configuration. Four samples with varying gold (Au) and tin dioxide (SnO2) layer thicknesses were fabricated and characterized using Atomic Force Microscopy (AFM). Experimental setups employed the Kretschmann configuration for reflectance spectrum analysis. Results indicate enhanced sensitivity and figure of merit (FoM) with an additional SnO2 layer compared to the case without SnO2. Particularly with a 36 nm Au thickness the sensitivity doubles and the FoM improves by 16 %. Numerical simulations validate these findings, confirming the optimized performance of HMR for specific layer thicknesses and incidence angles.
Open Access
Thin film coated D-shaped fiber regenerable biosensor
(Optica, 2020) Santano Rivero, Desiree; Ciáurriz Gortari, Paula; Tellechea Malda, Edurne; Zubiate Orzanco, Pablo; Socorro Leránoz, Abián Bentor; Del Villar, Ignacio; Matías Maestro, Ignacio; Arregui San Martín, Francisco Javier; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
We present a novel covalent functionalization of a D-shape fiber biosensor based on Lossy Mode Resonances. IgG/anti-IgG model is applied to prove the regeneration of the union and thus the re-usability of the sensor.
Open Access
Low-cost optical fiber multimode interference biosensor based on a glucose sensitive Glucose-Oxidase enzyme thin-film
(Elsevier, 2024-12-04) Rodríguez Rodríguez, Wenceslao Eduardo; Rodríguez Rodríguez, Adolfo Josué; Juárez-Saldivar, Alfredo; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
In this research we report a contribution for the development of low-cost fiber optical biosensors fabricated by the Single Mode-Multi Mode-Single Mode configuration applied for the glucose monitoring considering clinical concentrations ranges in aqueous analytes. Designed devices are evaluated using health standard detection ranges, such as healthy, pre-diabetic, and diabetic stages operating at the visible spectral region. The sensing regions has been prepared by the etching technique in order to improve the interaction between the evanescent wave with the surrounding medium followed by functionalization of enzyme oxidase glucose via the electrostatic self-assembly using by Poly(allylamine hydrochloride) as an immobilizer matrix. The increase of bilayers number over the sensor surface permits us to demonstrate the enhancement of sensitivity and limit of detection. Experimental results permitted the glucose characterization in the range from 0.3 to 2.4 mg mL-1 obtaining a response time of 9 s and a sensitivity of 1.8 nm/(mg mL-1) allowing to detect hypoglycemia and diabetes stages according to the World Health Organization standards.
Open Access
Biophotonic platform for detection of hallmarks of Alzheimer's disease via combined microfluidics and nanofunctionalized fiber sensors
(IEEE, 2023) Santano Rivero, Desiree; Lijiao, Zu; Jiwei, Xie; Peng, Liu; Zhang, Xuejun; Shi, Lei; Socorro Leránoz, Abián Bentor; Matías Maestro, Ignacio; Giannetti, Ambra; Baldini, Francesco; Santamaría Martínez, Enrique; Fernández Irigoyen, Joaquín; Li, Kaiwei; Bi, Wei; Van den Hove, Daniel L. A.; Del Villar, Ignacio; Guo, Tuan; Chiavaioli, Francesco; Ciencias de la Salud; Osasun Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
The emergence of Covid-19 pandemic has drawn large attention to vulnerable people affected by major diseases. According to the World Health Organization (WHO), more than 55 million people worldwide suffer from dementia. Alzheimer's disease (AD) is the predominant type of dementia, accounting for 60-70% of cases [1]. A long-standing challenge is to attain early diagnosis of AD hallmarks (tau protein, ¿P; amyloid beta, A¿) by detecting them in biological fluids, thus avoiding the labor of specialized hospital personnel and the high cost of imaging examinations. Different biological fluids are being used to detect AD biomarkers, such as cerebrospinal fluid (CSF), serum, blood-plasma [2]. Biomarker level in CSF has been shown to increase in the very early stages of the disease where its elevated value makes higher the risk of a quicker development of AD dementia. Traditional methods for biomarker detection are mostly based on ELISA or mass spectrometry, which possess well-known disadvantages in comparison with electrochemical or optical approaches [3,4].
Open Access
Lossy mode resonances generated in planar configuration for two-parameter sensing
(IEEE, 2021-04-29) Fuentes Lorenzo, Omar; Corres Sanz, Jesús María; Domínguez Rodríguez, Ismel; Del Villar, Ignacio; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
This work shows a new sensor structure for simultaneous measurement of two parameters, temperature and refractive index. The optical configuration consists of incidence of light on the edge of a soda-lime coverslip fully coated with a CuO thin film and partially coated with a PDMS thick layer. This planar configuration permitted to generate two separated lossy mode resonances (LMRs): one centered at 600 nm and the other at 1000 nm. The second resonance is induced by the PDMS layer and it can be used to measure the temperature due to its high thermo-optic coefficient (the sensitivity is -1.75 nm/°C in the temperature range from 20 to 40 °C), whereas the first resonance is used for sensing refractive index with sensitivity of 1460 nm/RIU in the refractive index range from 1.3328 and 1.37. Finally, a calibration test was carried out using a calibrated oil series with refractive index ranging from 1.33 to 1.36. This work demonstrates the possibility of generating multiples resonances in a single structure as simple as a coverslip, which can be used as a multi-parameter interchangeable sensor, especially suitable for biological applications or the detection of heavy metals in water.
Open Access
Polymer-functionalized fiber-optic optrode towards the monitoring of breathing parameters
(Institute of Electrical and Electronics Engineers Inc., 2023) Álvarez-Jiménez, A.; Acha Morrás, Nerea de; Aginaga Etxamendi, Concepción Isabel; Urrutia Azcona, Aitor; Socorro Leránoz, Abián Bentor; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
An innovative application of lossy mode resonances (LMRs) is presented in this work, pursuing the detection of biomedical variables. In this case, the detection of pH and breathing signal events is shown by means of a reflective fiber-optic optrode consisting of a poly(allylamine chloride) / poly (acrylic acid) polymer matrix deposited on the tip of a 200-micron-core bare multimode optical fiber. The proposed sensor is capable of detecting pH values between 6.5 and 8.0 (saliva pH range) with quite stability and repeatability. Moreover, when monitoring the breathing signal, the proposed sensor presents quite good real time detection of the different events occurring during the inspiration-expiration cycle, different breathing rates and detecting apneas.
Embargo
Hyperbolic mode resonance-based acetone optical sensors powered by ensemble learning
(Elsevier, 2024) 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.