Comunicacions a congressos (Enginyeria Electrònica i Biomèdica)

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Can QR Codes be used to readout Colorimetric Gas Sensors? A Back-Compatible Color QR Code with an Embedded CO2 Sensor Dye
(IEEE, 2024-12-17) Benito Altamirano, Ismael; Engel, Laura; Crugeira, Ferran; Marchena, Míriam; Fàbrega Gallego, Cristian; Wöllenstein, Jürgen; Prades García, Juan Daniel
Colorimetric dye readout devices have been explored extensively, with many approaches relying on complex hardware setups that stabilize the illuminant and capture conditions, typically involving attachments to smartphones or other digital cameras. In this work, we introduce a cost-effective sensor fabrication pipeline to embed a colorimetric dye in a QR Code, enabling readout by any standard smartphone without the need for specialized equipment. QR Codes, as established machine- readable patterns, offer a robust platform for integrating gasometric active dyes. Our approach ensures the preservation of QR Code data integrity by employing a novel method for maintaining back-compatibility throughout the pattern creation process, avoiding the limitations of dye placement solely in the center or outside the QR Code. We demonstrate this concept by embedding a CO2 sensor dye in a QR Code, while the QR Code presents a link to our website and a traceability ID. The dye is based on a pH-sensitive dye that changes color in the presence of CO2, focused on Modified Atmosphere Packaging (MAP) applications.
Dielectric excitation of Metal Oxide Semiconductor sensors: an exploratory performances analysis
(2024-06-18) Robbiani, Stefano; Benegiamo, Alessandro; Capelli, Laura; Marco Colás, Santiago; Dellacá, Raffaele
Metal Oxide Semiconductor (MOX) sensors are among the most widespread devices in chemical sensing, but their use is hindered due to several limitations, including crosssensitivity to temperature and humidity. Few studies suggested that the dielectric excitation readout of MOX sensors can increase the linearity and reduce cross-sensitivity. A bench test on two commercially available MOX sensors was designed and used to evaluate the dielectric excitation readout performances at different concentrations of acetone and ethanol when temperature and humidity were changed. Results show that not only both the real and imaginary parts of the sensors' electrical impedance are strongly frequency dependent, but also the dynamics of the sensors' response. Furthermore, the calculation of cross-sensitivity shows that there are regions of the spectra that allow for a reduction of cross-sensitivity to environmental interferences ranging from 2 to 10 times between 50 and 100 KHz.
DronE-Nose: drone-embedded measurement platform for odour monitoring
(2024-06-18) Alonso Valdesueiro, Javier; Marco Colás, Santiago; Gutiérrez Gálvez, Agustín
Electronic noses have improved in terms of reliability in the last two decades. Their design has allowed for model training and validation for predicting odour emissions and classifying odour sources. In the last few years, interest has turned to designing e-noses capable of flying in drones. Fast 3D mapping of areas where odour might become a problem, such as Wastewater Treatment Plants, Compost Plants, and Refineries, has been the main target of some recent studies. Here, a fully functional design of a drone-embedded, E-Nosebased measurement platform is presented. The design of its ENose and its fast-sampling frequency will allow for fast tracking of plumes and fast 3D odour mapping. In this contribution, a description of the system is provided in addition to preliminary measurements in the laboratory characterizing the fast response of the E-Nose to an odour stimulus.
Study of quality controls for stability check of the ROIs of a ketones mixture in different GC-IMS measurement campaigns
(IEEE, 2022-06-10) Mallafré Muro, Celia; Cruz, Meryl; Blanco i Borrego, Arnau; Fernández Romero, Lluís; Pardo Martínez, Antonio; Marco Colás, Santiago
GC-IMS is a very good complementary technique to traditional GC-MS, that presents some advantages, but also, some disadvantages such as misalignments produced by many parameters affecting the equipment stability. The reproducibility of the measures has been studied in two different measurement campaigns with a set of automatized quality control parameters. Figures of merit from one region of interest present in the samples show that the saturation and asymmetry do not change between measurement campaigns, but the volume and area of the total ion spectra change. A correction of these changes between batches should be developed.
Towards batch correction for GC-IMS data
(IEEE, 2022-06-10) Fernández Romero, Luis; Blanco i Borrego, Arnau; Mallafré Muro, Celia; Marco Colás, Santiago
Gas Chromatography Ion Mobility Spectrometry (GC-IMS) is a fast, non-expensive analytical technique that allows obtaining relevant chemical information from vapor mixtures. However, the technique presents some difficulties that should be solved to ensure reliable and reproducible results, namely: 1) data exhibits simultaneously high dimensionality and sparsity on their chemical information content, 2) data samples must usually be corrected even within a batch because of baseline and misalignment problems, 3) additional data corrections must be performed to prevent from chemical fingerprinting variations among batches. In this work, we have acquired data from two different batches (A and B) of ketone mixtures (2-Butanone, 2-Pentanone, 2-Hexanone, and 2-Heptanone). The analytical method for batch A and B was the same, except for the value of carrier gas flow parameter, which was approximately doubled for batch B. We have addressed problems 1) and 2) independently for each batch, obtaining as a result two peak tables. 3). Common peaks present in batches A and B were found after scaling the retention time axis of batch B and perform k-medoids clustering. Using this information, test data from batch B has been corrected through a linear transformation.
First characterization results obtained in a wind tunnel designed for indoor gas source detection
(IEEE, 2015-09-10) Martinez, D.; Clotet, E.; Tresanchez, M.; Moreno, J.; Jiménez Soto, J. M.; Magrans Nicieza, R.; Marco Colás, Santiago; Palacín, J.
This paper presents the preliminary characterization results of a custom wind tunnel for designed for performing experiments on locating a volatile gas source with a mobile robot. Such experiments require a previous characterization of the wind tunnel as well as the definition of the configurable agents which are present during the experiments. This paper presents the experimental data gathered from the real environments. This paper shows the behavior of the evolution and diffusion of the gas depending on the gas injection rate, the mobile robot position, and the wind force. The mobile robot is equipped with a LIDAR for self localization, with a photo ionization detector (PID) for gas measurement, and with an anemometer for wind measurement. This paper shows the results obtained in static and dynamic experiments.
ZIF-8 Films and Surface Plasmon Resonance for Chemical Vapor Detection
(MDPI, 2024-04-01) Estany Macià, Anna; Fort Grandas, Ignasi; Joshi, Nirav; Svendsen, Winnie Edith; Dimaki, Maria; Romano Rodríguez, Albert; Moreno Sereno, Mauricio
In this paper, we present a sensor that employs Zeolitic Imidazolate Frameworks (ZIF-8) on a Surface Plasmon Resonance sensor based on diffraction gratings to detect ethanol vapors via refractive index change in the porous structure.
Optical Interference Analysis of ZIF-8 Films for Chemical Vapor Detection
(MDPI, 2024-03-22) Estany Macià, Anna; Navale, Sachin; Fort Grandas, Ignasi; Joshi, Nirav; Romano Rodríguez, Albert; Moreno Sereno, Mauricio
Metal–organic frameworks (MOFs) are materials that feature a large surface area with permanent porosity, which is an attractive property for chemical and gas sensing, making them a good candidate for sensor fabrication. In this paper, we present a sensor that employs zeolitic-imidazolate- based MOFs (ZIF-8) to detect ethanol vapors via refractive index-dependent optical interference.
Improving Calibration of Chemical Gas Sensors for Fire Detection Using Small Scale Setups
(MDPI, 2017-08-09) Solórzano, Ana; Fonollosa Magrinyà, Jordi; Marco Colás, Santiago
Chemical sensing may be better suited than conventional smoke-based detectors for the detection of certain type of fires, in particular in fires where smoke appears after gas emissions. However, chemical-based systems also respond to non-fire scenarios that also release volatiles. For this reason, discrimination models need to be trained under different fire and non-fire scenarios. This is usually performed in standard fire rooms, the access to which is very costly. In this work, we present a calibration model combining experiments from standard fire room and small-scale setup. Results show that the use of small-scale setup experiments improve the performance of the system.
Adaptive Asymmetric Least Squares baseline estimation for analytical instruments
(IEEE Computer Society, 2014-02-11) Oller Moreno, Sergio; Pardo Martínez, Antonio; Jiménez Soto, Juan Manuel; Samitier i Martí, Josep; Marco Colás, Santiago
Automated signal processing in analytical instrumentation is today required for the analysis of highly complex biomedical samples. Baseline estimation techniques are often used to correct long term instrument contamination or degradation. They are essential for accurate peak area integration. Some methods approach the baseline estimation iteratively, trying to ignore peaks which do not belong to the baseline. The proposed method in this work consists of a modification of the Asymmetric Least Squares (ALS) baseline removal technique developed by Eilers and Boelens. The ALS technique suffers from bias in the presence of intense peaks (in relation to the noise level). This is typical of diverse instrumental techniques such as Gas Chromatography-Mass Spectrometry (GC-MS) or Gas Chromatography-Ion Mobility Spectrometry (GC-IMS). In this work, we propose a modification (named psalsa) to the asymmetry weights of the original ALS method in order to better reject large peaks above the baseline. Our method will be compared to several versions of the ALS algorithm using synthetic and real GC signals. Results show that our proposal improves previous versions being more robust to parameter variations and providing more accurate peak areas.
Ham quality evaluation assisted by gas chromatography ion mobility spectrometry
(Institute of Electrical and Electronics Engineers Inc., 2017-07-05) Fernández Romero, Luis; Martín Gómez, Andrés; Contreras, María del Mar; Padilla, Marta; Marco Colás, Santiago; Arce, Lourdes
In recent years, Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) has been successfully employed in food science as a control technique for the prevention of fraud according to food and labeling regulations. In this work, we propose the use of GC-IMS technique to assess the quality of Iberian ham with regard to the Iberian Pig's diet (either nourished with feed or with acorns). For this purpose, we have acquired a dataset composed of 53 samples of Iberian ham from different food providers using a commercial GC-IMS (FlavourSpec, from G.A.S. Dortmund, Germany). Intensive signal pre-processing for GC-IMS was applied to the raw data. This dataset was employed to create four Partial Least Squares Discriminant Analysis (PLSDA) models corresponding to different train/test partitions of the dataset. Nearly perfect classification rates (above 91 %) were obtained for each partition of the dataset, denoting the high power of GC-IMS to characterize food samples. © 2017 IEEE.
Colorimetric sensor for bad odor detection using automated color correction
(2017-06-02) Schmitt, K.; Tarantik, K.; Pannek, C.; Benito Altamirano, Ismael; Casals Guillén, Olga; Romano Rodríguez, Albert; Wöllenstein, Jürgen; Prades García, Juan Daniel
Colorimetric sensors based on color-changing dyes offer a convenient approach for the quantitative measurement of gases. An integrated, mobile colorimetric sensor can be particularly helpful for occasional gas measurements, such as informal air quality checks for bad odors. In these situations, the main requirement is high availability, easy usage, and high specificity towards one single chemical compound, combined with cost-efficient production. In this contribution, we show how a well stablished colorimetric method can be adapted for easy operation and readout, making it suitable for the untrained end user. As an example, we present the use of pH indicators for the selective and reversible detection of NH3 in air (one relevant gas contributing to bad odors) using gas-sensitive layers dip coated on glass substrates. Our results show that the method can be adapted to detect NH3 concentrations lower than 1 ppm, with measure-to-result times in the range of a few minutes. We demonstrate that the color measurements can be carried out with the optical signals of RGB sensors, without losing quantitative performance.
Mejora de la implicación del alumnado en “Diseño y síntesis de sistemas digitales” usando e-learning colaborativo, gamificación y aprendizaje basado en problemas
(2017-07) Alonso Casanovas, Oscar; Colomer i Farrarons, Jordi; Franch Masdeu, Nil; Diéguez Barrientos, Àngel
[eng] During the last 3 years, it has been observed that the students do not have a solid base to understand the concepts that are introduced in the subject. In addition, the attitude of the students, in general, is negligence, do not review concepts to prepare the subject, do not prepare laboratory practices and stop attending class. This results in a high dropout rate, fear of doing the subject and discomfort with the teaching staff. To solve this problem, we apply the teaching innovation presented in this article. Such innovation takes advantage of teaching strategies such as gamification or problem-based learning, uses virtual tools to motivate e-learning and collaboration with other students. The results, to date, are satisfactory since they reduce the dropout rate and increase the number of students who assimilate the concepts introduced in the subje
Low-cost fabrication of zero-power metal oxide nanowire gas sensors: trends and challenges
(Elsevier, 2015-09-11) Samà Monsonís, Jordi; Prades García, Juan Daniel; Casals Guillén, Olga; Barth, Sven; Gràcia Tortadés, Isabel; Cané i Ballart, Carles; Domènech Gil, Guillem; Hernández Ramírez, Francisco; Romano Rodríguez, Albert
Self-heating of metal oxide nanowires when a measuring current flows through them allows simultaneously heating the metal oxide, which is required for correct gas sensing operation, and measuring the nanowire resistance change, which is achieved from the ratio between the voltage drop at its edges and the current injected by the source measurement unit. In this way a drastic reduction of the power consumption of the gas sensor down to some μW is obtained and, additionally, it simplifies the practical operation of the devices, but the required control electronics that assures the correct and stable current flow through the device becomes much more complex. In this work the degree of maturity of this almost zero-power consuming gas detection systems based on nanowires will be shown and some recent advances in the use of nanowires mats or carbon nanofibers will be presented.
A low-cost approach to low-power gas sensors based on self-heating effects in large arrays of nanostructures
(2015-09-11) Monereo Cuscó, Oriol; Casals Guillén, Olga; Prades García, Juan Daniel; Cirera Hernández, Albert
The usual operation of a conductometric sensor device requires of an external energy source (i.e. an embedded heater). In the last years, the Joule effect in the sensing material, the so called self-heating effect, offered and alternative method to provide this energy: the probing current (or voltage) applied to measure the sensor signal also serves to heat up the sensor active film. Here, evidences of self-heating effects occurring on large arrays of nanostructures fabricated with low-cost methods are provided. The methodology is proven to be suitable to sense gases (humidity, NH3 and NO2) with low-powered heater-free devices.
Novel approaches towards highly selective self-powered gas sensors
(Elsevier, 2015-09-11) Hoffmann, Martin W. G.; Casals Guillén, Olga; Mayrhofer, Leonhard; Fàbrega i Claveria, Ma. Carme; Caccamo, Lorenzo; Hernández Ramírez, Francisco; Lilienkamp, Gerhard; Daum, Winfried; Moseler, Michael; Shen, Hao; Waag, Andreas; Prades García, Juan Daniel
The prevailing design approaches of semiconductor gas sensors struggle to overcome most of their current limitations such as poor selectivity, and high power consumption. Herein, a new sensing concept based on devices that are capable of detecting gases without the need of any external power sources required to activate interaction of gases with sensor or to generate the sensor read out signal. Based on the integration of complementary functionalities (namely; powering and sensing) in a singular nanostructure, self-sustained gas sensors will be demonstrated. Moreover, a rational methodology to design organic surface functionalization that provide high selectivity towards single gas species will also be discussed. Specifically, theoretical results, confirmed experimentally, indicate that precisely tuning of the sterical and electronic structure of sensor material/organic interfaces can lead to unprecedented selectivity values, comparable to those typical of bioselective processes. Finally, an integrated gas sensor that combine both the self-powering and selective detection strategies in one single device will also be presented.
Locally grown SnO2 NWs as low power ammonia sensor
(Elsevier, 2015-09-11) Samà Monsonís, Jordi; Barth, Sven; Jiménez Díaz, Román; Prades García, Juan Daniel; Casals Guillén, Olga; Gràcia Tortadés, Isabel; Cané i Ballart, Carles; Romano Rodríguez, Albert
Localized growth of SnO2 nanowires on top of CMOS compatible micromembranes that incorporate a buried heater and prepatterned interdigitated electrodes has been achieved that presents the advantage that it allows to easily and directly integrate the advantageous properties of quasi-one dimensional structures in an advanced electronic device by a Vapor Liquid Solid (VLS) mechanism. A NWs based sensor of this type is characterized as a low power gas sensor towards NH3 at different temperatures. Stable and reproducible response is obtained, that allows detecting concentrations below the time-weighted average exposure limit for 8 h.

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