La salud y el bienestar siempre han sido el centro de atención de muchas instituciones de investigación y empresas de todo el mundo. Esto llevó a la tecnología a desarrollarse en los campos químico, biológico, médico y clínico con el objetivo de proporcionar una mejor protección al ser humano. Como consecuencia, ha surgido una competición entre el tiempo necesario para que la enfermedad progrese y el tiempo necesario para que el hombre trate dicha enfermedad. Para ganar esta competición, es necesario actuar con anticipación, cuando la enfermedad aún no está demasiado desarrollada. Esto es posible realizando una detección precoz de la enfermedad. El logro de este objetivo allana el camino para el desarrollo de dispositivos ópticos de biosensado capaces de detectar la presencia de ciertas moléculas en concentraciones extremadamente bajas. Entre ellos, las estructuras integradas fotónicas están teniendo un gran éxito debido a su considerablemente alta sensibilidad. Sin embargo, el mecanismo de detección de estas estructuras se basa en la interacción entre la onda evanescente, que se propaga a lo largo de la superficie de la estructura, y el analito a detectar. De esta forma, no todo el campo que se propaga en la estructura fotónica se usa con fines de detección, sino solo una pequeña cantidad de éste. Esto representa una limitación crucial de los sensores basados en fotónica integrada. El objetivo de esta tesis doctoral es superar esta limitación y desarrollar estructuras fotónicas de sensado más sensibles que sean capaces de detectar las concentraciones más bajas posibles. Con este objetivo, nos centramos en el estudio del silicio poroso como plataforma para el desarrollo de estructuras ópticas con sensibilidades extremadamente altas gracias a que la interacción de sensado se realiza directamente dentro de la propia estructura, lo que permite explotar todo el campo que se propaga. / Health and well-being have always been the center of attention of many research institutions and companies around the world. This led the technology to develop in the chemical, biological, medical and clinical fields with the aim to provide a better protection to the human being. As a consequence, a competition is born between the time necessary to the disease to progress and the time necessary to man to treat such disease. In order to win this competition, it is necessary to act with anticipation, when disease is not too developed yet. This is possible by performing an early-detection. The achievement of this goal paves the way for the development of optical biosensing devices able to detect the presence of certain molecules at extremely low concentrations. Among them, photonic integrated structures are finding a great success due to their considerably high sensitivity. However, the sensing mechanism of these structures is based on the interaction between the evanescent wave, propagating along the structure surface, and the target analyte to detect. In this way, not all the field propagating in the photonic structure is used for sensing purposes, but rather only a small amount of it. This represents a crucial limitation of the integrated photonics based sensors. The aim of this PhD Thesis is to overcome this limitation and to develop more sensitive photonic sensing structures able to detect the lowest concentration possible. To this aim, we focused on the study of porous silicon as platform for the development of optical structures with extremely high sensitivities thanks to the fact that the sensing interaction takes place directly inside the structure itself, allowing to exploit all the field propagating in the structure. / La salut i el benestar sempre han sigut el centre d'atenció de moltes institucions de recerca i empreses de tot el món. Açò va portar a la tecnologia a desenvolupar-se en els camps químic, biològic, mèdic i clínic amb l'objectiu de proporcionar una millor protecció a l'ésser humà. Com a conseqüència, ha sorgit una competició entre el temps necessari per que la malaltia progresse i el temps necessari per que l'home tracte aquesta malaltia. Per a guanyar aquesta competició, és necessari actuar amb anticipació, quan la malaltia encara no està massa desenvolupada. Açò és possible realitzant una detecció precoç de la malaltia. L'assoliment d'aquest objectiu facilita el camí per al desenvolupament de dispositius òptics de biosensat capaços de detectar la presència de certes molècules en concentracions extremadament baixes. Entre ells, les estructures fotòniques integrades estan tenint un gran èxit a causa de la seua considerablement alta sensibilitat. No obstant açò, el mecanisme de detecció d'aquestes estructures es basa en la interacció entre l'ona evanescent, que es propaga al llarg de la superfície de l'estructura, i l'analit a detectar. D'aquesta forma, no tot el camp que es propaga en l'estructura fotònica s'usa amb finalitats de detecció, sinó solament una xicoteta quantitat d'aquest. Açò representa una limitació crucial dels sensors basats en fotònica integrada. L'objectiu d'aquesta tesi doctoral és superar aquesta limitació i desenvolupar estructures fotòniques de sensat més sensibles que siguen capaces de detectar les concentracions més baixes possibles. Amb aquest objectiu, ens centrem en l'estudi del silici porós com a plataforma per al desenvolupament d'estructures òptiques amb sensibilitats extremadament altes gràcies a que la interacció de sensat es realitza directament dins de la pròpia estructura, el que permet explotar tot el camp que es propaga. / Caroselli, R. (2018). Development of high sensitivity photonic sensing structures based on porous silicon substrates [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107318 / TESIS

La spectroscopie dans le moyen-infrarouge est une méthode universelle pour identifier les substances chimiques et biologiques, car la plupart des molécules ont leurs résonances de vibration et de rotation dans cette plage de longueurs d'onde. Les systèmes moyen infrarouge disponibles dans le commerce reposent sur des équipements volumineux et coûteux, tandis que de nombreux efforts sont maintenant consacrés à la réduction de leur taille et leur intégration sur circuits intégrés. L’utilisation de la technologie silicium pour la réalisation de circuits photoniques dans le moyen-infrarouge présente de nombreux avantages: fabrication fiable, à grand volume, et réalisation de circuits photoniques à hautes performances, compacts, légers et à faible consommation énergétique. Ces avantages sont particulièrement intéressant pour les systèmes de détection spectroscopique moyen infrarouge, qui besoin d'être portable et à faible coût. Parmi les différents matériaux disponibles en photonique silicium, les alliages silicium-germanium (SiGe) à forte concentration en Ge sont particulièrement intéressants en raison de la grande fenêtre de transparence du Ge, pouvant atteindre 15 µm. Dans ce contexte, l'objectif de cette thèse est d'étudier une nouvelle plate-forme SiGe à forte concentration en Ge, pour la démonstration de circuits photoniques moyen infra rouge. Cette nouvelle plate-forme devrait bénéficier d'une large gamme de transparence en longueurs d'onde de transparence et de la possibilité d’ajuster les propriétés des guides optiques (indice effectif, dispersion,…). Au cours de cette thèse, différentes plates-formes basées sur différents profils graduels du guide d’onde ont été étudiées. Tout d'abord, il a été démontré qu’il était possible d’obtenir des guides présentant de faibles pertes optiques inférieures à 3 dB/cm dans une large plage de longueurs d'onde, de 5,5 à 8,5 µm. Une preuve de concept de détection de molécules, basée sur l'absorption de la partie évanescent du mode optique a ensuite été démontrée. Ensuite, les composants formant les briques de base classiques de la photonique intégrée ont été étudiés. Les premières cavités intégrées ont été réalisées à 8 µm. Deux configurations ont été étudiées : des cavité Fabry-Perot utilisant des miroirs de Bragg intégrés dans les guides d’onde et des résonateurs en anneau. Un spectromètre à transformée de Fourier fonctionnant sur une large bande spectrale, et pour les deux polarisations de la lumière a également été démontré. Tous ces résultats reposent sur la conception des matériaux et des composants, la fabrication en salle blanche et la caractérisation expérimentale. Ce travail a été effectué dans le cadre du projet européen INsPIRE en collaboration avec le Pr. Giovanni Isella de Politecnico Di Milano. / Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances, as most of the molecules have their vibrational and rotational resonances in the mid-IR wavelength range. Commercially available mid-IR systems are based on bulky and expensive equipment, while lots of efforts are now devoted to the reduction of their size down to chip-scale dimensions. The use of silicon photonics for the demonstration of mid-IR photonic circuits will benefit from reliable and high-volume fabrication to offer high performance, low cost, compact, lightweight and power consumption photonic circuits, which is particularly interesting for mid-IR spectroscopic sensing systems that need to be portable and low cost. Among the different materials available in silicon photonics, Germanium (Ge) and Silicon-Germanium (SiGe) alloys with a high Ge concentration are particularly interesting because of the wide transparency window of Ge up to 15 µm. In this context, the objective of this thesis is to investigate a new Ge-rich graded SiGe platform for mid-IR photonic circuits. Such new plateform was expected to benefit from a wide transparency wavelength range and a high versatility in terms of optical engineering (effective index, dispersion, …). During this thesis, different waveguides platforms based on different graded profiles have been investigated. First it has been shown that waveguides with low optical losses of less than 3 dB/cm can be obtained in a wide wavelength range, from 5.5 to 8.5 µm. A proof of concept of sensing based on the absorption of the evanescent component of the optical mode has then been demonstrated. Finally, elementary building blocs have been investigated. The first Bragg mirror-based Fabry Perot cavities and racetrack resonators have been demonstrated around 8 µm wavelength. A broadband dual-polarization MIR integrated spatial heterodyne Fourier-Transform spectrometer has also been obtained. All these results rely on material and device design, clean-room fabrication and experimental characterization. This work was done in the Framework of EU project INsPIRE in collaboration with Pr. Giovanni Isella from Politecnico Di Milano.

<p>Thin film photovoltaic materials have garnered much interest recently due to their processability in addition to good properties for conversion of solar photons to usable energy. Amine-thiol chemistry has shown the ability to produce solution processed materials such as Cu₂ZnSn(S,Se)₄ (CZTSSe), a thin film absorber composed of earth abundant metals. Using similar solution processing methods as those used to produce CZTS, we wish to synthesize a phase pure solution processed material from molecular precursors of metals and metal chalcogenides into an Ag₂ZnSnSe₄ absorber which lacks the electronic defects that plague CZTSSe. Additionally, we will utilize the reactive dissolution of metal in amine-thiol solution chemistry for a more detailed understanding of how metal-sulfur complexes form and then decompose into films, to gain insight about the conditions that produce stable solutions and high quality films for a better ability to optimize processing conditions. </p><p><br></p><p>We find we are able to individually dissolve zinc metal, tin metal, and silver sulfide precursors to produce solutions of metal thiolate complexes. Based on results from electrospray ionization mass spectrometry (ESI-MS), proton nuclear magnetic resonance (¹H-NMR), and extended X-ray absorption fine structure (EXAFS)/ X-ray absorption near edge spectra (XANES) we propose that these structures contain thiolate molecules coordinated with Ag, Zn, and Sn in the +1, +2, and +2 oxidation states respectively. However, mixing these produces an AZTS solution which is only stable for 3 hours, due to a redox reaction between Ag⁺ and Sn²⁺ which forms Sn⁴⁺ and insoluble Ag metal. To solve this, we synthesize SnS₂ and show this produces a different Sn-thiolate complex with fully oxidized Sn⁴⁺. This is then used to produce the first stable AZTS solution, an essential step to fabricating reproducible films. We use this AZTS solution to fabricate films containing AZTS, and selenize these films in a tube furnace to produce films which contain AZTSe as well as secondary phases. We then use rapid thermal processing furnace to remove some of these secondary phases, and discuss ways to further improve our material quality.<br></p><p></p>

This project examines how the collective oscillation of electrons in optically excited metal nanoparticles ( diameter < 100 nm) is affected by the presence of different dielectric environments. When coupled with material polarization, these collective oscillations are known as a Surface Plasmon Polaritons (SPPs), which preferentially absorb and scatter light at a specific frequency satisfying the Local Surface Plasmon Resonance (LSPR) condition. Surface plasmons on metal nanoparticles are widely studied for use in optical labeling, ultrasensitive biodetection, and thermally activated tissue treatment. In general Mie theory can be used to accurately model the optical behavior of ideal spherical particles in a homogeneous environment. However, many experiments involving LSPRs deal with metal nanoparticles in inhomogeneous environments; a typical experimental procedure involves the deposition of a colloidal suspension of metal nanoparticles directly onto a substrate. This project explains how the LSPR of nanoparticles deposited onto planar substrates depends upon the polarization of incident radiation, and demonstrates evidence of resonance tuning by comparing the optical response in various dielectric environments.

This dissertation studies, analyzes, and experimentally demonstrates the innovative use of interference phenomenon in the field of opto-electronic information processing and optical communications. A number of optical systems using interferometric techniques both in the optical and the electronic domains has been demonstrated in the filed of signal transmission and processing, optical metrology, defense, and physical sensors. Specifically it has been shown that the interference of waves in the form of holography can be exploited to realize a novel optical scanner called Code Multiplexed Optical Scanner (C-MOS). The C-MOS features large aperture, wide scan angles, 3-D beam control, no moving parts, and high beam scanning resolution. A C-MOS based free space optical transceiver for bi-directional communication has also been experimentally demonstrated. For high speed, large bandwidth, and high frequency operation, an optically implemented reconfigurable RF transversal filter design is presented that implements wide range of filtering algorithms. A number of techniques using heterodyne interferometry via acousto-optic device for optical path length measurements have been described. Finally, a whole new class of interferometric sensors for optical metrology and sensing applications is presented. A non-traditional interferometric output signal processing scheme has been developed. Applications include, for example, temperature sensors for harsh environments for a wide temperature range from room temperature to 1000 degree C.

This thesis proposes research of novel hybrid photonic signal processing systems in the areas of optical communications, test and measurement, RF signal processing and extreme environment optical sensors. It will be shown that use of innovative hybrid techniques allows design of photonic signal processing systems with superior performance parameters and enhanced capabilities. These applications can be divided into domains of analog-digital hybrid signal processing applications and free-space--fiber-coupled hybrid optical sensors. The analog-digital hybrid signal processing applications include a high-performance analog-digital hybrid MEMS variable optical attenuator that can simultaneously provide high dynamic range as well as high resolution attenuation controls; an analog-digital hybrid MEMS beam profiler that allows high-power watt-level laser beam profiling and also provides both submicron-level high resolution and wide area profiling coverage; and all optical transversal RF filters that operate on the principle of broadband optical spectral control using MEMS and/or Acousto-Optic tunable Filters (AOTF) devices which can provide continuous, digital or hybrid signal time delay and weight selection. The hybrid optical sensors presented in the thesis are extreme environment pressure sensors and dual temperature-pressure sensors. The sensors employ hybrid free-space and fiber-coupled techniques for remotely monitoring a system under simultaneous extremely high temperatures and pressures.

Bioelectronics effectively bridges the gap between the biochemical and the electrical domains, integrating aspects of biology, electronics, physics, and material science to foster innovative solutions and impact the trajectory of human health and environmental science, by translating biological responses into electrical signals for advanced analysis. Despite its transformative potential, current bioelectronic systems face limitations in terms of scalability, sensitivity, and ease of integration. This thesis claims that co-designing Complementary Metal-Oxide-Semiconductor (CMOS) integrated circuits with highly specific and sensitive genetically engineered biosensors is pivotal in bioelectronics evolution, offering high accuracy, reliability, miniaturization, and multiplexed sensing capabilities essential for addressing challenges in healthcare, environmental monitoring, sustainable manufacturing, and beyond. To support this claim, this dissertation highlights two key contributions: a low-power ingestible sensor for gastrointestinal tract monitoring and a hybrid platform technology combining droplet microfluidics and CMOS electronics for impedance spectroscopy and luminescence sensing for rapid screening and optimization of biosensors under different environmental conditions. The first contribution details an ingestible capsule that could transform healthcare diagnostics through a novel threshold-crossing-based detector and CMOS-integrated photodiodes. This innovation exemplifies how hybrid bioelectronic systems can significantly improve the precision and non-invasiveness of real-time health monitoring. Moving beyond the traditional scope of bioelectronics and the sole purpose of health monitoring, the second contribution extends its application by integrating droplet microfluidics with CMOS chips, facilitating high-throughput droplet screening to optimize biosensor performance for application deployment. To achieve this goal, this platform is equipped with a low-noise, high-resolution CMOS impedance spectroscopy chip and a high-resolution CMOS luminescence detector chip. In highlighting these contributions, the thesis reinforces the assertion that hybrid bioelectronic systems are key to addressing a wide range of societal challenges. Moreover, the integration of synthetic biology and microfluidics with CMOS technology, as demonstrated in this work, not only overcomes existing barriers, such as achieving miniaturization, high sensitivity, rapid data processing, and energy efficiency, but also paves the way for future innovations with extensive potential in personalized medicine and environmental sustainability. / 2026-01-17T00:00:00Z

No description available.

This thesis presents an experimental study on how to track zero gaps between metal sheets to be joined by laser beam butt welding. Automated laser beam welding is gaining interest due to its ability to produce narrow and deep welds giving limited heat input and therefore less distortions compared to other processes, such as arc-welding. The automated laser beam welding process is however sensitive to how the high power laser is positioned with regards to the joint position. Deviations from the joint position may occur due to inaccuracies of the welding robot and fixturing, changes in joint geometry, process induced distortions, etc. Welding with an offset from the joint position can result inlack of sidewall fusion, a serious defect that is hard to detect. This work develops and evaluates three monitoring systems to be used during welding in order to be able to later control the laser beam spot position. (i) A monitoring systemis developed for three different photo diodes, one for the visual spectrum of the process emissions, one for the infrared spectrum, and one for the reflected highpower laser light. The correlation between the signals from the photodiodes and the welding position relative to the joint is analysed using a change detection algorithm. In this way an indication of a path deviation is given. (ii) A visual camera with matching illumination and optical filters is integrated into the laser beam welding tool in order to obtain images of the area in front of the melt pool. This gives a relatively clear view of the joint position even during intense spectral disturbances emitted from the process, and by applying animage processing algorithm and a model based filtering method the joint positionis estimated with an accuracy of 0.1 mm. (iii) By monitoring the spectral emissions from the laser induced plasma plume using a high speed and high resolution spectrometer, the plasma electron temperature can be estimated from the intensities of two selected spectral lines and this is correlated to the welding position and can be used for finding the joint position.

Our motivation for this work is based on the need to monitor the cure and inservice health of composite materials. We describe the continuation of an effort to design a multi-functional fiber optic sensor which can be embedded in polymeric composite laminates for monitoring the degree of cure during its fabrication, as well as internal composite strains occurring post-cure.3 In short, this dual-purpose sensor combines the characteristics of a Fresnel reflectometer with those of the extrinsic Fabry-Perot interferometer. For monitoring cure, a broadband source is used so the output intensity of the sensor is amplitude-modulated as the refractive index of the composite is increased during the polymerization process. Post-cure, a coherent light source is implemented so a. sinusoidal variation of the output signal occurs when strains within the composite cause the sensor output to be phase-modulated. We demonstrate the measurement of refractive index with the Fresnel reflectometer/EFPL and test it as an embedded refractive index monitor. Our experimental results demonstrate that the refractive index of 5-minute epoxy increases by approximately 2 % during the cure process. In addition, the sensor can be used as an interferometer to measure internal composite strains, where the phase difference between consecutive fringe peaks is one-half the wavelength of the source. / Master of Science