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[EN] Regular screening of point mutations is of importance to cancer management and treatment selection. Although techniques like next-generation sequencing and digital polymerase chain reaction (PCR) are available, these are lacking in speed, simplicity, and cost-effectiveness. The development of alternative methods that can detect the extremely low concentrations of the target mutation in a fast and cost-effective way presents an analytical and technological challenge. Here, an approach is presented where for the first time an allele-specific PCR (AS-PCR) is combined with a newly developed high fundamental frequency quartz crystal microbalance array as biosensor for the amplification and detection, respectively, of cancer point mutations. Increased sensitivity, compared to fluorescence detection of the AS-PCR amplicons, is achieved through energy dissipation measurement of acoustically ¿lossy¿ liposomes binding to surface-anchored dsDNA targets. The method, applied to the screening of BRAF V600E and KRAS G12D mutations in spiked-in samples, was shown to be able to detect 1 mutant copy of genomic DNA in an excess of 104 wild-type molecules, that is, with a mutant allele frequency (MAF) of 0.01%. Moreover, validation of tissue and plasma samples obtained from melanoma, colorectal, and lung cancer patients showed excellent agreement with Sanger sequencing and ddPCR; remarkably, the efficiency of this AS-PCR/acoustic methodology to detect mutations in real samples was demonstrated to be below 1% MAF. The combined high sensitivity and technology-readiness level of the methodology, together with the ability for multiple sample analysis (24 array biochip), cost-effectiveness, and compatibility with routine workflow, make this approach a promising tool for implementation in clinical oncology labs for tissue and liquid biopsy.

© 2021 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., [EN] Improvement of data acquisition rate remains as an important challenge in applications with Quartz Crystal Microbalance (QCM) technology where high throughput is required. To address this challenge, we developed a fast method capable of measuring the response of a large number of sensors and/or overtones, with a high time resolution. Our method, which can be implemented in a low-cost readout electronic circuit, is based on the estimation of fr (frequency shift) and D (dissipation shift) from measurements of the sensor response obtained at a single driving frequency. By replacing slow fitting procedures with a direct calculation, the time resolution is only limited by the physical characteristics of the sensor (resonance frequency and quality factor), but not by the method itself. Capabilities of the method are demonstrated by monitoring multiple overtones with a single 5 MHz sensor and a Monolithic QCM array comprising 24 50MHz-sensors. Accuracy of the method is validated and compared with the state-of-the-art, as well as with a reference method based on impedance analysis.

© 2020 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., [EN] Miniaturized, high-throughput, cost-effective sensing devices are needed to advance lab-on-a-chip technologies for healthcare, security, environmental monitoring, food safety, and research applications. Quartz crystal microbalance with dissipation (QCMD) is a promising technology for the design of such sensing devices, but its applications have been limited, until now, by low throughput and significant costs. In this work, we present the design and characterization of 24-element monolithic QCMD arrays for high-throughput and low-volume sensing applications in liquid. Physical properties such as geometry and roughness, and electrical properties such as resonance frequency, quality factor, spurious mode suppression, and interactions between array elements (crosstalk), are investigated in detail. In particular, we show that the scattering parameter, S 21 , commonly measured experimentally to investigate crosstalk, contains contributions from the parasitic grounding effects associated with the acquisition circuitry. Finite element method simulations do not take grounding effects into account explicitly. However, these effects can be effectively modelled with appropriate equivalent circuit models, providing clear physical interpretation of the different contributions. We show that our array design avoids unwanted interactions between elements and discuss in detail aspects of measuring these interactions that are often-overlooked.

[ES] Para hacer frente al cambio climático, estamos cambiando nuestro modelo energético con el fin de reducir el impacto que tiene sobre la Tierra la producción de dicha energía. En el presente documento nos centramos en la energía solar fotovoltaica, uno de los métodos más punteros actualmente. Los módulos fotovoltaicos son un elemento fundamental para producir este tipo de energía, ya que son los encargados de generarla. Por este motivo, es muy importante tenerlos y mantenerlos en condiciones óptimas, ya que por el contario la eficiencia de la instalación se vería muy reducida. Como primer paso será necesario tener una idea de los diferentes fallos, anomalías o tipos de degradación que pueden sufrir los paneles solares. Una vez visto lo que nos podemos encontrar, pasaremos a ver las diferentes técnicas y métodos utilizados para encontrar estos fallos. Tras ver la teoría, describiremos las herramientas utilizadas para realizar las mediciones en campo, entre las que se encuentran los elementos que componen el laboratorio móvil y las diferentes cámaras utilizadas. Analizaremos diferentes muestras tomadas en situaciones reales de medida. Finalmente, sacaremos conclusiones sobre el estado y la velocidad de degradación que tienen los módulos instalados. Fijándonos también en las posibles diferencias que puedan tener los paneles según el fabricante y la técnica de fabricación., [EN] To beat the climate change, we are changing our energy model to reduce the impact that the production of this energy has on the Earth. In this document we focus on the Photovoltaic Solar Energy, one of the most leading methods today. Photovoltaic modules are a fundamental element to produce that kind of energy since they are in charge of generating it. For this reason, it is very important to have them and keep them in optimal conditions, since, on the contrary, the efficiency of the installation would be greatly reduced. As first step, it will be necessary to have an idea of the different failures, anomalies, or types of degradation that solar panels can suffer. Once seen what we can find, we will go to see the different techniques and methods used to find these faults. After seeing the theory, we will describe the tools used to perform field measurements, among which are the elements that make up the mobile laboratory and the different chambers used. We will analyse different samples taken in real measurement situations. Finally, we will draw conclusions about the status and rate of degradation of the installed modules. Also looking at the possible differences that the panels may have depending on the manufacturer and the manufacturing technique.

[EN] Monolithic quartz crystal microbalance (MQCM) has recently emerged as a very promising technology suitable for biosensing applications. These devices consist of an array of miniaturized QCM sensors integrated within the same quartz substrate capable of detecting multiple target analytes simultaneously. Their relevant benefits include high throughput, low cost per sensor unit, low sample/reagent consumption and fast sensing response. Despite the great potential of MQCM, unwanted environmental factors (e.g., temperature, humidity, vibrations, or pressure) and perturbations intrinsic to the sensor setup (e.g., mechanical stress exerted by the measurement cell or electronic noise of the characterization system) can affect sensor stability, masking the signal of interest and degrading the limit of detection (LoD). Here, we present a method based on the discrete wavelet transform (DWT) to improve the stability of the resonance frequency and dissipation signals in real time. The method takes advantage of the similarity among the noise patterns of the resonators integrated in an MQCM device to mitigate disturbing factors that impact on sensor response. Performance of the method is validated by studying the adsorption of proteins (neutravidin and biotinylated albumin) under external controlled factors (temperature and pressure/flow rate) that simulate unwanted disturbances.

[EN] Integrating acoustic wave sensors into lab-on-a-chip (LoC) devices is a well-known challenge. We address this challenge by designing a microfluidic device housing a monolithic array of 24 high-fundamental frequency quartz crystal microbalance with dissipation (HFF-QCMD) sensors. The device features six 6-µL channels of four sensors each for low-volume parallel measurements, a sealing mechanism that provides appropriate pressure control while assuring liquid confinement and maintaining good stability, and provides a mechanical, electrical, and thermal interface with the characterization electronics. We validate the device by measuring the response of the HFF-QCMD sensors to the air-to-liquid transition, for which the robust Kanazawa¿Gordon¿Mason theory exists, and then by studying the adsorption of model bioanalytes (neutravidin and biotinylated albumin). With these experiments, we show how the effects of the protein¿surface interactions propagate within adsorbed protein multilayers, offering essentially new insight into the design of affinity-based bioanalytical sensors

[EN] In this study, a piezoelectric immunosensor based on High Fundamental Frequency Quartz Crystal Microbalance (HFF-QCMD) technology was developed for detection of sulfathiazole in honey. The biorecognition was based on a competitive immunoassay in the conjugate-coated format, using monoclonal antibodies as specific im-munoreagents. The quantification of sulfathiazole was performed by building the corresponding calibration standard curve in diluted honey (1/140). Due to the competitive nature of the immunoassay, the standard curve showed a sigmoidal pattern with limits of detection (LOD) and quantification (LOQ) of 0.10 ¿g/kg and 2 ¿g/kg honey, respectively. The LOD reached by this immunosensor is 40¿50 times lower than those reported by other techniques for antibiotic detection. Moreover, this method requires minimum honey pre-treatment, making it faster and simpler than other methods. This immunosensor meets the precision and accuracy requirements established by SANCO guidelines, when sulfathiazole concentration in honey is not lower than 10 ¿g/kg. These findings could be the basis for reaching enough reliability for lower concentrations. Therefore, HFF-QCMD immunosensors can be considered a feasible alternative to current techniques for rapid and highly sensitive determination of sulfathiazole in honey with minimum sample preparation.

[EN] BACKGROUND: In recent years there has been a concern about the presence of pesticides in honey because residues of DDT and carbaryl were found in honey samples. Traditional techniques, such as chromatography, reach the required limits of detection (LOD) but are not suitable for in situ implementation in the honey-packaging industry due to their high cost and the need for highly quali¿ed staff for routine operation. Biosensors offer simplicity, low cost, and easy handling for analytical purposes in food applications. RESULTS: Piezoelectric immunosensors based on high fundamental frequency quartz crystal microbalance (HFF-QCM) have been developed for the detection of carbaryl and DDT in honey. Biorecognition was based on competitive immunoassays in the conjugate-coated format, using monoclonal antibodies as speci¿c immunoreagents. The assay LODs attained by the HFF-QCM immunosensors were 0.05 ~gL¿1 for carbaryl and 0.24 ~gL¿1 for DDT, reaching a similar level of detectability to that of the usual reference techniques. The practical LODs in honey samples were 8 ~gkg¿1 for carbaryl and 24 ~gkg¿1 for DDT. The immunosensors¿ analytical performance allow the detection of these pesticides in honey at EU regulatory levels with good accuracy (recovery percentages ranging from 94% to 130% within the working range of each pesticide standard curve) and precision (coef¿cients of variation in the 9¿36% range). CONCLUSION: The proposed immunosensor is a promising analytical tool that could be implemented for quality control in the honey packaging industry, to simplify and to reduce the cost of the routine pesticide analysis in this appreciated natural food.

[ES] Tras el estudio de las energías renovables y el aumento de consumo de energía en términos generales, se ha buscado mejorar y entender mejor el uso de la energía solar. Después de concluir que uno de los retos a los que se desafía la energía fotovoltaica es que es poco predecible, se ha desarrollado un algoritmo para la predicción de la radiación solar y temperatura para un punto en concreto del mundo a través de técnicas de inteligencia artificial, en concreto, redes neuronales. Se analizan 3 tipos de redes neuronales pertenecientes a los diferentes grupos de redes neuronales, redes estáticas, las cuales solo permiten el flujo de datos en un sentido, y las redes dinámicas, las cuales cuentan con memoria y permiten el flujo de datos en ambos sentidos. También se estudia qué tipo de red neuronal, así como su estructura, tiene una mejor eficiencia para los datos con los que se están tratando. Además, se han estudiado las diferentes tecnologías de células fotovoltaicas utilizadas con las cuales haciendo uso de las redes neuronales se podría concluir cual es la tecnología más apropiada para cierta instalación fotovoltaica. Palabras clave: Radiación, temperatura, inteligencia artificial, redes neuronales, energía fotovoltaica, células fotovoltaicas., [EN] After studying renewable energies and the increase of the energy consumption in general terms, we have sought to improve and better understand the use of solar energy. Afterwards, it has been concluded that one of the challenges that the photovoltaic energy has to face is that it is not very predictable, therefore an algorithm has been developed for the forecasting of solar radiation and temperature for a specific point in the world through artificial intelligence techniques, specifically, neural networks. 3 different types of neural networks are analysed which belong to two different types of neural network structures, the static structures, which only allow the flow of data in one direction, and dynamic structures, which allow the flow of the data in both directions. In addition, also different structures of those types of neural networks have been considered and tested, comparing which one of them was having a better efficiency for the data which we are dealing with. Moreover, the different photovoltaic cell technologies which are currently being used in the market have been studied and by the use of neural networks, we would be able to conclude which type of cell technology is the most appropriate technology for a certain photovoltaic installation.

[ES] Este proyecto consiste en el desarrollo de un ecosistema que permita realizar un seguimiento de las cargas de consumo eléctrico en una vivienda inteligente. Disponemos de un frigorífico, un aire acondicionado, una lámpara, un calentador de agua y un horno conectado cada uno a un dispositivo inteligente que recoge el consumo de la carga y su estado ON/OFF. El usuario será capaz de elegir entre tres modelos de consumo diferentes: económico, energético o comfort. Cada modelo desconectará o conectará estos dispositivos dependiendo de lo que se especifique, que va en función de la hora en la que la carga esté activa y del consumo de esta. Para implementarlo se utilizará un servidor de acceso gratuito y libre denominado HOME ASSISTANT, que se encontrará dentro de una máquina virtual en un dispositivo WINDOWS que se estará ejecutando en todo momento. Se desarrollará también la metodología de la aplicación a utilizar por el usuario para la elección del modelo y cómo se implementa su conexión con el servidor., [EN] This project consists of developing an ecosystem that allows monitoring the electricity consumption loads in an intelligent home. There is a refrigerator, an air conditioner, a lamp, a water heater, and a furnace each one connected to an intelligent device that collects the load's consumption and its state ON/OFF. The user will be able to choose between three different consumption models: economic, energy or comfort. Each model will disconnect or connect these devices depending on what was specified in that model, this is in relation to the time in which the charge is active and its consumption. To deploy it, a free access server called HOME ASSISTANT will be implemented, which will be located inside a virtual machine in a WINDOWS device that will always be running. The methodology of the user's application will also be developed for the selection of a model and how its connection to the server will be implemented.

[EN] A new heterogeneous integration method is presented that allows the integration of a microfluidic platform and a multi-channel quartz crystal microbalance array on a printed circuit board (PCB) using a dry adhesive bonding method. In this work, the microfluidic platform is a replica molded using a UV-curable OSTEMER 322 Crystal Clear polymer. The OSTEMER acts both as a final package for the cartridge and as a functional material for hosting molded microfluidic channels, the input reservoirs and the waste reservoir. The method is demonstrated by the integration of an array of 24 of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) to the OSTEMER microfluidic packaging. The resulting bond interface is shown to be completely homogeneous and void free, and the package is tested to a differential pressure of up to 4 bars. The leak test of the cartridge is performed by pressurizing a microfluidic channel with an aqueous solution using an external peristaltic pump for more than 4 h. The cartridge performance is evaluated by the electrical characterization. Q-factor values of 9507 and of 650are achieved in air and DI water, respectively. Results show that this simple integration method of the HFF-QCM is a promising way to integrate microfluidics into the more complex heterogeneous system.

Desarrollar un programa que emule un generador de una turbina eólica mediante un motor PMSM con DSP (DRV8312) con un microprocesador de la familia C2000 de Texas Instruments, para poder realizar simulaciones de viento, estableciendo un comportamiento real de un generador y alimentar a una carga gracias a un rectificador trifásico., Analysis and design of an emulator of an educational wind turbine. Implementation of hardware and software that emulates a wind turbine using a PMSM engine. The digital control will be done through the digital processor of the Texas C2000 family and the DRV8312 power board of Texas Instruments, to be able to perform wind simulations, establishing a real behavior of a generator and controlling the magnitudes of Wind, Speed and Power by means of a variable three-phase load. This load will be implemented through an active rectifier and a resistive load.

[EN] Quantification of chemical residues in honey is a market requirement to ensure consumer safety. The most common method used to analyze these compounds is the LC/MS/MS methodology, which requires highly qualified technicians and a tedious pre-treatment of the sample. The honey-packaging industry needs cheaper and faster alternatives for routine control. HFF-QCM (High Fundamental Frequency Quartz Crystal Microbalance) sensors are becoming a good option due to their high sensitivity, fast detection and low cost, while avoiding complex sample pre-treatment. The HFF-QCM technology is based on piezoelectric sensors with frequencies in the range from several tenths of MHz to hundreds of MHz. In this work a 100 MHz HFF-QCM sensor was used in a monoclonal antibody-based competitive immunoassay for specific bio-recognition of carbaryl pesticide as testing contaminant. The work intends to validate the use of HFF-QCM technology, in comparison with liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique, for the detection of contaminants in honey. For this purpose, the validation criteria required by SANCO 12571/2013 guidance document were considered. The precision and accuracy (recovery) of both methods were determined by comparison of 5 replicates at 4 different concentrations (from 0 to 100 ¿g/kg) using the same honey matrix. HFF-QCM technology showed good accuracy, with recovery percentages always between 110 and 120%. As regards to precision, HFF-QCM coefficients of variation (CV) were around 10% higher than those recommended by GC SANCO 12571/2013. HFF-QCM limits of detection (LOD) and quantification (LOQ) were in the same order of magnitude as those for LC-MS/MS, which allows the analysis of carbaryl residues in honey under the established maximum residue limits (MRL), without sample pre-treatment. These results show that biosensors based on HFF-QCM technology has become a serious alternative to the traditional analytical techniques for food quality and s

[EN] Acoustic wave resonators have become suitable devices for a broad range of sensing applications due to their sensitivity, low cost, and integration capability, which are all factors that meet the requirements for the resonators to be used as sensing elements for portable point of care (PoC) platforms. In this work, the design, characterization, and validation of a 150 MHz high fundamental frequency quartz crystal microbalance (HFF-QCM) sensor for bio-sensing applications are introduced. Finite element method (FEM) simulations of the proposed design are in good agreement with the electrical characterization of the manufactured resonators. The sensor is also validated for bio-sensing applications. For this purpose, a specific sensor cell was designed and manufactured that addresses the critical requirements associated with this type of sensor and application. Due to the small sensing area and the sensor's fragility, these requirements include a low-volume flow chamber in the nanoliter range, and a system approach that provides the appropriate pressure control for assuring liquid confinement while maintaining the integrity of the sensor with a good base line stability and easy sensor replacement. The sensor characteristics make it suitable for consideration as the elemental part of a sensor matrix in a multichannel platform for point of care applications.

Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization. Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen. For the development of the HFF piezoelectric immunosensor, 100 MHz quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through mixed self-assembled monolayers (mSAM) of carboxylic alkane thiols. A competitive immunoassay based on Myc-31 MAb was integrated with the transducer as sensing bio-recognition event. Reliable assay signals were obtained using low concentrations of antigen for functionalization and MAb for the competitive immunoassay. Under optimized conditions, the HFF immunosensor calibration curve for 38 kDa determination showed a limit of detection as low as 11 ng mL-1 of the biomarker. The high detectability attained by this immunosensor, in the picomolar range, makes it a promising tool for the easy, direct and sensitive detection of the tuberculosis biomarker in biological fluids such as sputum.

Proyecto final de carrera que trata del diseño y desarrollo de un nuevo sistema de telecontrol de riego para los parques y jardines del Ayuntamiento de Murcia. Uno de los requisitos que debe de cumplir este sistema, es que los programadores de riego instalados en los jardines deben de conectarse con el servidor de control a través de la red de telecomunicaciones wifi municipal. El presente proyecto se desarrolla en una empresa del sector industrial, por lo que para el diseño y desarrollo de la solución adoptada se utizarán elementos típicos de la automatización industrial, como son los autómatas programables (PLCS) y los SCADAS de control (Supervisión, Control y Adquisión de datos).

[EN] In spite of being widely used for in liquid biosensing applications, sensitivity improvement of conventional (5-20 MHz) quartz crystal microbalance (QCM) sensors remains an unsolved challenging task. With the help of a new electronic characterization approach based on phase change measurements at a constant fixed frequency, a highly sensitive and versatile high fundamental frequency (HFF) QCM immunosensor has successfully been developed and tested for its use in pesticide (carbaryl and thiabendazole) analysis. The analytical performance of several immunosensors was compared in competitive immunoassays taking carbaryl insecticide as the model analyte. The highest sensitivity was exhibited by the 100 MHz HFF-QCM carbaryl immunosensor. When results were compared with those reported for 9 MHz QCM, analytical parameters clearly showed an improvement of one order of magnitude for sensitivity (estimated as the I50 value) and two orders of magnitude for the limit of detection (LOD): 30 µg L-1 vs 0.66 µg L-1 I50 value and 11 µg L-1 vs 0.14 µg L-1 LOD, for 9 and 100 MHz, respectively. For the fungicide thiabendazole, I50 value was roughly the same as that previously reported for SPR under the same biochemical conditions, whereas LOD improved by a factor of 2. The analytical performance achieved by high frequency QCM immunosensors surpassed those of conventional QCM and SPR, closely approaching the most sensitive ELISAs. The developed 100 MHz QCM immunosensor strongly improves sensitivity in biosensing, and therefore can be considered as a very promising new analytical tool for in liquid applications where highly sensitive detection is required.

[EN] Investigating the electrical sensitivity of lateral field excited resonators (LFE) we observed two characteristics to highly impact sensitivity. First, an increase of the piezoelectric coupling factor k enhances the viscosity measurement range. Higher coupling factors are provided by the use of new materials, namely lithium tantalite (LiTaO3) and lithium niobate (LiNbO3) with coupling factors of 0.43 and 0.91 respectively. Since the sensitivity to electrical load parameters is governed by relative permittivity of the resonator material itself, the sensitivity to electrical parameters is found to decrease for new materials. Second, an electrode pattern that reveals higher energy trapping in the center of crystal was investigated. Compared to common LFE pattern, a third electrode was introduced in center between bite wing electrodes. Finite element modeling in ANSYS (c) shows enhanced sensitivity to low relative permittivity in range from 1 to 8. We performed experiments to verify the simulation results. Although an increased frequency shift compared to common LFE resonators was not observed, significantly higher conductance amplitudes occurred, which enhances the measurement range to high viscosity liquids, too. (C) 2012 Elsevier B.V. All rights reserved.

Introduction. Artifactual variations in the ST segment may lead to confusion with acute coronary syndromes. Objective. To evaluate how the technical characteristics of the recording mode may distort the ST segment. Material and Method. We made a series of electrocardiograms using different filter configurations in 45 asymptomatic patients. A spectral analysis of the electrocardiograms was made by discrete Fourier transforms, and an accurate recomposition of the ECG signal was obtained from the addition of successive harmonics. Digital high-pass filters of 0.05 and 0.5 Hz were used, and the resulting shapes were compared with the originals. Results. In 42 patients (93%) clinically significant alterations in ST segment level were detected. These changes were only seen in “real time mode” with high-pass filter of 0.5 Hz. Conclusions. Interpretation of the ST segment in “real time mode” should only be carried out using high-pass filters of 0.05 Hz.

L'Electrogravimetria AC empra una microbalança de quars electroquímica (EQCM) en règim dinàmic. En l'EQCM un dels elèctrodes d'or depositats sobre el cristall és recobert amb una fina pelolícula d'un polímer electroactiv i és emprat com a elèctrode de treball (WE) dins d'una celola electroquímica. Les variacions de la freqüència de ressonància de la microbalança de quars (QCM) permeten obtindre la resposta massa associada amb la transferència de càrrega que es dóna en la interfície polímer-electròlit. L'Electrogravimetria AC va ser proposta a fi de caracteritzar i separadament identificar el moviment dels ions i el solvent en la interfície polímer-electròlit. En esta tècnica s'analitza en el domine de la freqüència la resposta de massa davant de xicotetes pertorbacions de voltatge gràcies a l'ocupació de la microbalança de quars en règim dinàmic. Per a este propòsit s'aplica una xicoteta pertorbació sinusoidal superposada a una tensió contínua, entre l'elèctrode de referència i l'elèctrode de treball de la celola. Posteriorment, es pot dibuixar la funció de transferència electrogravimètrica (EGTF), definida esta com la raó (?m/?E) entre l'amplitud dels canvis de massa induïts (?m) i l'amplitud de la pertorbació sinusoïdal aplicada (?E). Esta funció de transferència se dibuixa en un pla complex per a cada una de les freqüències de la senyal de pertorbació. Les distintes espècies iònicas involucrades són identificades en el pla complex per mitjà de bucles característics sempre que els bucles no se superposen. Per mitjà d'esta tesi doctoral es proposa un nou sistema de conversió de freqüència-tensió basat en un doble ajust de freqüència implementat amb un PLL mesclant elements analògics i digitals (AD PLL). Els resultats trobats tant en la caracterització electrònica del dispositiu com en la fase experimental proven la fiabilitat del sistema per als mesuraments realitzats en la tècnica d'Electrogravimetria AC.

This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm(2) in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected.

The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequencymass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed. © 2011 American Institute of Physics.

[EN] Quartz crystal is generally used in some applications as a microbalance taking advantage of its capacity to change the resonance frequency according to any surface mass change on the resonator.In this way a quartz crystal can be used as a transducer in a piezoelectric inmunosensor system in order to detect antigen-antibody bonds. An interface for Quartz Crystal Microbalances, QCM, based on an improved version of an oscillator in balanced differential configuration and its respective validation as a biosensor characterization system is introduced in this paper. The system was successfully tested in a piezoelectric inmunosensor for detecting the pesticide Carbaryl., [ES] El cristal de cuarzo generalmente es usado en aplicaciones como microbalanza, aprovechando la capacidad que presenta éste para variar su frecuencia de resonancia de acuerdo a los cambios de la densidad superficial de masa depositada en la superficie del resonador. De esta manera, un cristal de cuarzo puede ser utilizado como transductor en un sistema de inmunosensor piezoeléctrico, para detectar uniones antígeno – anticuerpo. En este artículo se presenta una interfaz para microbalanzasde cristal de cuarzo, QCM (del inglés Quartz Crystal Microbalance) basado en una versión mejorada de oscilador en configuración diferencial equilibrado y su validación como sistema de caracterización para biosensores. El sistema fue probado con éxito en un inmunosensor piezoeléctrico para la detección del plaguicida Carbaryl.

Acoustic wave resonator techniques are widely used in in-liquid biochemical applications. The main challenges remaining are the improvement of sensitivity and limit of detection, as well as multianalysis capabilities and reliability. The sensitivity improvement issue has been addressed by increasing the sensor frequency, using different techniques such as high fundamental frequency quartz crystal microbalances (QCMs), surface generated acoustic waves (SGAWs) and film bulk acoustic resonators (FBARs). However, this sensitivity improvement has not been completely matched in terms of limit of detection. The decrease on frequency stability due to the increase of the phase noise, particularly in oscillators, has made it impossible to increase the resolution. A new concept of sensor characterization at constant frequency has been recently proposed based on the phase/mass sensitivity equation: ¿¿/¿m ¿ -1/m L, where m L is the liquid mass perturbed by the resonator. The validation of the new concept is presented in this article. An immunosensor application for the detection of a low molecular weight pollutant, the insecticide carbaryl, has been chosen as a validation model. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

This work deals with the design of a high sensitivity DNA sequence detector using a 50 MHz quartz crystal microbalance (QCM) electronic oscillator circuit. The oscillator circuitry is based on Miller topology, which is able to work in damping media. Calibration and experimental study of frequency noise are carried out, finding that the designed sensor has a resolution of 7.1 ng/cm 2 in dynamic conditions (with circulation of liquid). Then the oscillator is proved as DNA biosensor. Results show that the system is able to detect the presence of complementary target DNAs in a solution with high selectivity and sensitivity. DNA target concentrations higher of 50 ng/mL can be detected. © 2011 by the authors; licensee MDPI, Basel, Switzerland.

La microbalanza de cristal de cuarzo (QCM) se usa como técnica alternativa de análisis químico, donde las aplicaciones dependen directamente de la sensibilidad del cristal. Por tanto, es el parámetro más importante que determina el uso de los cristales de cuarzo frente a otras técnicas. La ecuación de Sauerbrey, teóricamente relaciona la variación de la densidad de masa en la superficie del cristal con el cambio de la frecuencia y al mismo tiempo predice que la sensibilidad aumenta en la misma proporción que el cuadrado de la frecuencia fundamental de resonancia serie del cristal. Aumentar la frecuencia fundamental de trabajo para aumentar la sensibilidad, es una necesidad; el objetivo principal de esta tesis doctoral es estudiar los sistemas de caracterización de resonadores de cuarzo, que se usan en la actualidad y proponer un sistema o una mejora a los ya existentes que permitan el uso de cristales de cuarzo de alta frecuencia de fundamental (HFF-QCM). De los sistemas que en la actualidad caracterizan a la microbalanza de cuarzo, se destacan los analizadores de impedancia y los osciladores, como métodos de caracterización de HFF-QCM. Los analizadores, por su gran tamaño y coste, quedan relegados a su uso como instrumento de referencia en el laboratorio. Los osciladores en cambio, por su bajo coste, su capacidad de integración, su sencillez del circuito y la monitorización continua de frecuencia de oscilación, lo hacen adecuados como interfaz para sistemas sensores basados en QCM. En esta tesis, se propone un sistema oscilador, basado en un oscilador diferencial equilibrado, como sistema de caracterización de cristales a 10 MHz, estudiándose el comportamiento del circuito, la capacidad de este sistema para compensar la capacitancia paralela del cristal, las aplicación de este tipo de interfaz para la caracterización de líquidos y finalmente se desarrollo una aplicación como inmunosensores piezoeléctricos para la detección del pesticida Carbaryl.

El trabajo presentado en esta tesis doctoral profundiza sobre el fenóme-no rugoso superficial y su contribución a la respuesta acústica del cristal resonador de cuarzo en medios líquidos. Su principal aportación se centra en el estudio de los parámetros geométricos que pueden representar de forma óptima la contribución rugosa sobre la impedancia acústica del sen-sor. Se propone un modelo empírico del efecto rugoso basado en los resul-tados de este estudio. Otra de las aportaciones de la presente tesis se centra en el estudio detallado de uno de los modelos de rugosidad propuestos más recientemente: el modelo de Arnau. Este modelo plantea la posibilidad de modelar la rugosidad mediante una distribución de casquetes semi-esféricos. En esta tesis se propone una corrección semi-empírica de dicho modelo que permita incluir el efecto de interferencia entre casquetes. Esta corrección se emplea en el estudio del comportamiento del efecto rugoso en superficies aleatorias. Se ha demostrado que el efecto de la rugosidad de una superficie aleatoria en la impedancia acústica puede ser modelado por la respuesta de una superficie equivalente formada por una distribución re-gular de casquetes semi-esféricos sobre una superficie plana. Asimismo, se ha demostrado que los parámetros geométricos de esta superficie equiva-lente están linealmente correlacionados con la proyección de la superficie aleatoria real en la dirección del movimiento. Esta afirmación se ha com-probado mediante medidas experimentales con microscopio de fuerza atómica (AFM). Palabras Clave: Piezoelectricidad, sensores de cuarzo, rugosidad, modo de cizalla en espesor.