Contributions to the design of energy harvesting systems for autonomous sensors in low power marine applications

Tesi en modalitat de compendi de publicacionsOceanographic sensor platforms provide biological and meteorological data to help understand changes in marine environment and help to preserve it. Lagrangian drifters are autonomous passive floating platforms used in climate research to obtain surface marine data. They are low-cost, versatile, easy-to-deploy and can cover large extensions of the ocean when deployed in group. These deployments can last for years, so one of the main design challenges is the autonomy of the drifter. Several energy harvesting (EH) sources are being explored to reduce costs in battery replacement maintenance efforts such as solar panels. Drifters must avoid the impact of the wind because this may compromise proper surface current tracking and therefore, should ideally be mostly submerged. This interferes with the feasibility of solar harvesting, so other EH sources are being explored such as the oscillatory movement of the drifter caused by ocean waves. Wave energy converters (WEC) are the devices that turn this movement into energy. The motion of the drifter can principally be described by 3 oscillatory degrees of freedom (DoF); surge, heave and pitch. The heave motion includes the buoyancy’s response of the drifter, which can be explained by a mass-spring-damping model. By including the wave’s hydrodynamic load in this model, it is converted into a nonlinear system whose frequency response includes the wave’s frequency and the natural frequencies from the linear system. A smart option to maximize the captured energy is to design the inner WEC with a natural frequency similar to that of the drifter's movement. In this thesis, a 4 DoF model is obtained. This model includes the heave, the surge and the pitch motion of the drifter in addition to the inner pendulum motion relative to the buoy. Simultaneously, different pendulum-type WECs for small-size oceanic drifters are proposed. One of these converters consists of an articulated double-pendulum arm with a proof mass that generates energy through its relative motion with the buoy. Different experimental tests are carried out, with a prototype below 10 cm in diameter and 300 g of total mass, proving the capability of harvesting hundreds of microwatts in standard sea conditions EH sources require an additional power management unit (PMU) to convert their variable output into a constant and clean source to be able to feed the sensor electronics. PMUs should also ensure that the maximum available energy is harvested with a maximum power point tracking (MPPT) algorithm. Some sources, such as WECs, require fast MPPT as its output can show relatively rapid variations. However, increasing the sampling rate may reduce the harvested energy. In this thesis, this trade-off is analyzed using the resistor-based fractional open circuit voltage-MPPT technique, which is appropriate for low-power EH sources. Several experiments carried out in marine environments demonstrate the need for increasing the sampling rate. For this purpose, the use of a commercial PMU IC with additional low-power circuitry is proposed. Three novel circuits with a sampling period of 60 ms are manufactured and experimentally evaluated with a small-scale and low-power WEC. Results show that these configurations improve the harvested energy by 26% in comparison to slow sampling rate configurations. Finally, an EH-powered oceanographic monitoring system with a custom wave measuring algorithm is designed. By using the energy collected by a small-size WEC, this system is capable of transmitting up to 22 messages per day containing data on its location and measured wave parameters.Les plataformes d’observació oceanogràfiques integren sensors que proporcionen dades físiques i biogeoquímiques de l’oceà que ajuden a entendre canvis en l’entorn marí. Un exemple d’aquestes plataformes són les boies de deriva (drifters), que són dispositius autònoms i passius utilitzats en l’àmbit de la recerca climàtica per obtenir dades in-situ de la superfície marina. Aquests instruments són de baix cost, versàtils, fàcils de desplegar i poden cobrir grans superfícies quan s’utilitzen en grup. L’autonomia és un dels principals desafiaments en el disseny de drifters. Per tal d’evitar els costos en la substitució de bateries, s’estudien diferents fonts de captació d’energia com per exemple la solar. Els drifters utilitzats per l’estudi dels corrents marins superficials han d’evitar l’impacte directe del vent ja que afecta al correcte seguiment de les corrents i, per tant, cal que estiguin majoritàriament submergides. Això compromet la viabilitat de l’energia solar, fet que requereix l’estudi d’altres fonts de captació com el propi moviment de la boia causat per les onades. Els convertidors d’energia de les onades (WEC, wave energy converters) compleixen aquesta funció. El moviment dels drifters pot explicar-se bàsicament a través de 3 graus de llibertat oscil·latoris: la translació vertical i la horitzontal i el balanceig. La translació vertical inclou la flotabilitat del dispositiu, que es pot descriure mitjançant el model massamolla- amortidor. Incloure la càrrega hidrodinàmica de l’onada en aquest model el converteix en un sistema no lineal amb una resposta freqüencial que inclou la de l’onada i les naturals del sistema lineal. Una opció per maximitzar l’energia captada és dissenyar el WEC amb una freqüència natural similar a la del moviment de la boia. En aquesta tesis es proposa un model de 4 graus de llibertat per a l’estudi del moviment del drifter. Aquest inclou els 3 graus de llibertat de la boia i el moviment del pèndul relatiu a ella. En paral·lel, es proposen diferents WEC del tipus pendular per drifters de reduïdes dimensions. Un d’aquests WEC consisteix en un doble braç articulat amb massa flotant que genera energia a través del seu moviment relatiu al drifter. S’han dut a terme diferents proves experimentals amb un prototip inferior a 10 cm de diàmetre i 300 g de massa, les quals demostren la seva capacitat de captar centenars de microwatts en condicions marines estàndard. Utilitzar fonts de captació d’energia requereix incloure una unitat gestora de potència (PMU, power management unit) per tal de convertir la seva sortida variable en una font constant i neta que alimenti l’electrònica dels sensors. Les PMU també tenen la funció d’assegurar que es recull la màxima energia mitjançant un algoritme de seguiment del punt de màxima potència. Els WEC requereixen un seguiment d’aquest punt ràpid perquè la seva sortida consta de variacions relativament ràpides. Tanmateix, augmentar la freqüència de mostreig pot reduir l’energia captada. En aquesta tesi, s'analitza a fons aquesta relació utilitzant la tècnica de seguiment de la tensió en circuit obert fraccionada basada en resistències, que és molt adequada per a fonts de baixa potència. Diversos experiments realitzats en el medi marí mostren la necessitat d'augmentar la freqüència de mostreig, així que es proposa l'ús de PMU comercials amb una electrònica addicional de baix consum. S’han fabricat tres circuits diferents amb un període de mostreig de 60 ms i s’han avaluat experimentalment en un WEC de reduïdes dimensions. Els resultats mostren que aquestes configuracions milloren l'energia recollida en un 26% en comparació a PMU amb mostreig més lent. Finalment, s’ha dissenyat un sistema autònom de monitorització marina que inclou un algoritme de mesura d'ones propi. Aquest sistema és capaç de transmetre fins a 22 missatges al diaPostprint (published version

Electrochemical Plug-and-Power e-readers for Point-of-Care Applications

Point-of-Care diagnostic tests enable monitor health conditions and obtain fast results close to the patient, reducing medical costs, and allowing the control of infectious outbreaks. The interest in developing Point-of-Care devices is increasing due to they are suitable for a wide variety of applications. This doctoral thesis focuses on the development of Plug-and-Power electronic readers (e- readers) for electrochemical detections and the demonstration of their possibilities as Point-of-Care diagnostic testing. The solutions proposed in this study make it possible to improve Point-of-Care tests whose premises are laboratory decentralization, personalized medicine, rapid diagnosis, and improvement of patient care. Developed electronic readers can be powered from a conventional system, such as a USB port or a lithium battery, or can be defined as self-powered systems, capable of extracting energy from alternative energy sources, such as fuel cells, defining Plug-and-Power systems. The designed electrochemical detection devices in this thesis are based on low-power consumption electronic instrumentation circuits. These circuits are capable of controlling the sensing element, measuring its response, and representing the result quantitatively. The implemented devices can work with both electrochemical sensors and fuel cells. Furthermore, it is possible to adapt its measurement range, enabling its use in a wide variety of applications. Thanks to their reduced energy consumption, some of these developments can be defined as self-powered platforms able to operate only with the energy extracted from the biological sample, which in turn is monitored. These devices are easy-to-use and plug-and-play, enabling those unskilled individuals to carry out tests after prior training. Moreover, thanks to their user-friendly interface, results are clear and easy to understand. This doctoral dissertation is presented as an article compendium and composed of three publications detailed in chronological order of publication. The first contribution describes an innovative portable Point-of-Care device able to provide a quantitative result of the glucose concentration of a sample. The proposed system combines an e-reader and a disposable device based on two elements: a glucose paper-based power source, and a glucose fuel cell-based sensor. The battery-less e-reader extracts the energy from the disposable unit, acquires the signal, processes it, and shows the glucose concentration on a numerical display. Due to low-power consumption of the e-reader, the whole electronic system can operate only with the energy extracted from the disposable element. Furthermore, the proposed system minimizes the user interaction, which only must deposit the sample on the strip and wait a few seconds to see the test result. The second publication validates the e-reader in other scenarios following two approaches: using fuel cells as a power element, and as a dual powering and sensing element. The device was tested with glucose, urine, methanol, and ethanol fuel cells and electrochemical sensors in order to show the adaptability of this versatile concept to a wide variety of fields beyond clinical diagnostics, such as veterinary or environmental fields. The third study presents a low-cost, miniaturized, and customizable electronic reader for amperometric detections. The USB-powered portable device is composed of a full- custom electronic board for signal acquisition, and software, which controls the systems, represents and saves the results. In this study, the performance of the device was compared against three commercial potentiostats, showing comparable results to those obtained using three commercial systems, which were significantly more expensive. As proof of concept, the system was validated by detecting horseradish peroxidase samples. However, it could be easily extended its scope and measure other types of analytes or biological matrices since it can be easily adapted to detect currents a wide range of currents.Las pruebas de diagnostico Point-of-Care permiten monitorizar las condiciones de salud y obtener resultados rápidos cerca del paciente, reduciendo los costes médicos y permitiendo controlar brotes infecciosos. El interés por desarrollar dispositivos de Point- of-Care está aumentando debido a que son aplicables a una amplia variedad de aplicaciones. Esta tesis doctoral se centra en el desarrollo de lectores electrónicos (e-readers) Plug-and- Power para detecciones electroquímicas y la demostración de sus posibilidades como pruebas de diagnóstico de punto de atención (Point-of-Care). Las soluciones propuestas en este trabajo permiten mejorar las pruebas Point-of-Care, cuyas premisas son la descentralización de laboratorio, la medicina personalizada, el diagnóstico rápido y la mejora de la atención al paciente. Los lectores electrónicos desarrollados pueden ser alimentados desde un sistema convencional, como puede ser un puerto USB o una batería de litio, o definirse como sistemas autoalimentados, capaces de extraen energía de fuentes alternativas de energía, como celdas de combustible (fuel cells), definiendo así sistemas Plug-and-Power. Los dispositivos de detección electroquímica diseñados se basan en circuitos de instrumentación electrónica de bajo consumo. Estos circuitos son capaces controlar el elemento de sensado, medir su respuesta y representar el resultado de forma cuantitativa. Los dispositivos implementados pueden trabajar tanto con sensores electroquímicos como con fuel cells. Además, es posible adaptar su rango de medida, permitiendo su utilización en una amplia variedad de aplicaciones. Gracias a su reducido consumo de energía, algunos de estos desarrollos pueden definirse como plataformas autoalimentadas capaces de operar solo con la energía extraída de la muestra biológica, que a su vez es monitorizada. Estas plataformas electrónicas son fáciles de usar y Plug-and-Play, permitiendo que personas no cualificadas puedan utilizarlas después de un previo entrenamiento. Además, gracias a su interfaz fácil de usar, los resultados son claros y fáciles de interpretar

Contribution au domaine de la conception d’objets communicants embarqués basse consommation et autonomes en énergie

This report proposes a synthesis of my research and teaching activities. Since 2008, as associate professor at the University of Nice Sophia Antipolis, I did my research into the MCSOC team from the LEAT laboratory. For nearly 15 years, my activity is focused on the design of embedded communicating objects, with a strong emphasis for high level approach allowing, early in the design flow, to model and optimize the performance as well as the consumed energy. Those system-level approaches are more and more relevant over the last few years and become a must-have solution for designing efficient embedded systems. My activity on energy harvesting for autonomous systems brings an original contribution to this domain and has a national and international impact. This document is organized in two parts: the first part is a synthesis of my research and teaching activity, while the second one presents in details my research work, putting in evidence my contributions and innovative aspects. The manuscript ends with a scientific overview as well as some perspectives.Ce manuscrit présente une synthèse de mes travaux de recherche. Depuis septembre 2008, date de ma nomination en tant que Maître de Conférences à l’Université de Nice Sophia Antipolis, j’ai effectué mes travaux de recherche au sein de la thématique MCSOC (Modélisation, Conception Système d’Objets Communicants) du laboratoire LEAT (Université de Nice Sophia Antipolis, UMR CNRS 7248). Depuis maintenant près de 15 ans, mes travaux de recherche s’intéressent au domaine de la conception d’objets communicants embarqués avec une évolution forte vers des approches de haut niveau d’abstraction permettant tôt dans le flot de conception, de modéliser et d’optimiser les performances et la consommation d’énergie. Ces approches de niveau système n’ont cessé de prendre de l’ampleur ces dernières années et s’installent aujourd’hui comme une solution incontournable du domaine de la conception de systèmes embarqués. Mes travaux plus spécifiques sur l’autonomie énergétique de ces systèmes apportent une contribution originale au domaine et ont un rayonnement national et international. Ce document est organisé en deux parties : la première partie propose une synthèse des travaux de recherche et d’enseignement ; la seconde présente de manière détaillée mes travaux de recherche en mettant en avant toutes ses contributions et originalités. Le manuscrit s’achève par un bilan scientifique ainsi que quelques perspectives de recherche

Capture opportuniste d'énergie micro-onde pour l'autonomie des objets communicants

In recent years, the decrease of electronic components consumption has led to the development of wireless devices. An interesting application concerns Internet of Things (IoT) and Wireless Sensor Networks (WSNs). Sensors are used in various scenarios such as intelligent monitoring systems for office, home automation, medical or military applications. Today these sensors are powered by batteries. Despite significant progress, batteries still have a limited lifetime and their replacement is often complicated. This explains the motivation to find alternative ways to power these objects. A promising method consists in harvesting energy from the ambient environment of the sensor nodes. For instance, thermal gradients, mechanical vibrations, light or electromagnetic waves could serve such a purpose. This thesis has been funded by PRACOM and has been held in this context. The thesis aim is to contribute to the development of innovative solutions to design self-powered sensor networks particularly by exploiting the energy of Radio Frequency (RF) waves. These sensors are located in ambient environment, i.e. an environment for which the RF power densities are not controlled and generally low. First of all, different sources and energy harvesting techniques have been investigated. This study helps to position the RF energy harvesting to other systems such as the mechanical, thermal, chemical, photovoltaic energy. After having demonstrated the added value of harvesting energy over a wide frequency band, a statistical study has been conducted to evaluate the RF power density in urban environment and countryside. The sensor environment involves choices for the chosen architecture, such as the addition of an energy storage cell or the use of a dc-dc converter. Several multi-band RF harvesters have been designed and tested in various environments. They show the feasibility of powering small sensors. The issue of autonomous sensors worn by the person is also addressed. The study highlights how the presence of the human body has an impact on RF harvester performance. Several solutions are proposed such as the improvement of the impedance matching network or the use of a high impedance surface.Les réseaux de capteurs sans fil (WSN: Wireless Sensor Network), l'Internet des objets (IOT), profitent des progrès récents en terme de consommation énergétique pour concevoir des entités de contrôle intelligentes. Les batteries ou piles ont permis le développement de ces systèmes en les rendant autonomes. Néanmoins, cette méthode d'alimentation est inadaptée pour les applications modernes. Une solution alternative pour alimenter ces capteurs est d'utiliser l'énergie disponible dans leur environnement, comme par exemple les gradients thermiques, les vibrations mécaniques, ou encore les ondes lumineuses ou Radio-Fréquences. C'est dans ce contexte que s'est déroulé ce travail de thèse financé par PRACOM. Cette thèse propose de contribuer au developpement de solutions innovantes visant à rendre autonome en énergie un réseau de capteurs en exploitant notamment l'énergie des ondes Radio-Fréquences (RF). Ces capteurs sont placés en environnement ambiant, c'est-à-dire dans un environnement pour lequel les densités de puissances incidentes ne sont pas maîtrisées et sont généralement faibles. Tout d'abord différentes sources et techniques de récupération d'énergie ont été étudiées comme l'énergie mécanique, thermique, chimique et celle des ondes lumineuses et Radio-Fréquences. Cette étude a permis de positionner les systèmes de récupération d'énergie des ondes Radio Fréquences par rapport aux autres systèmes. Après avoir démontré l'intérêt de collecter l'énergie sur une large bande de fréquence, une étude statistique a été menée sur l'évaluation de la densité de puissance RF présente dans un environnement urbain et à la campagne. L'environnement du capteur implique des choix pour l'architecture choisie, comme par exemple l'ajout de cellule de stockage d'énergie ou encore l'utilisation d'un convertisseur dc-dc. Plusieurs récupérateurs d'énergie RF multibandes ont été conçus et testés dans divers environnements. Ceux-ci montrent la faisabilité d'alimenter des petits capteurs en extérieur. La problématique des capteurs autonomes en énergie portés par la personne est également abordée. Il s'agit de voir comment la présence du corps humain a un retentissement sur les performances du système de récupération d'énergie RF. Plusieurs solutions sont proposées comme l'amélioration du réseau d'adaptation d'impédances du récupérateur d'énergie RF, ou encore l'utilisation d'une surface à hautes impédances

Predicting the Future

Due to the increased capabilities of microprocessors and the advent of graphics processing units (GPUs) in recent decades, the use of machine learning methodologies has become popular in many fields of science and technology. This fact, together with the availability of large amounts of information, has meant that machine learning and Big Data have an important presence in the field of Energy. This Special Issue entitled “Predicting the Future—Big Data and Machine Learning” is focused on applications of machine learning methodologies in the field of energy. Topics include but are not limited to the following: big data architectures of power supply systems, energy-saving and efficiency models, environmental effects of energy consumption, prediction of occupational health and safety outcomes in the energy industry, price forecast prediction of raw materials, and energy management of smart buildings

ATHENA Research Book, Volume 2

ATHENA European University is an association of nine higher education institutions with the mission of promoting excellence in research and innovation by enabling international cooperation. The acronym ATHENA stands for Association of Advanced Technologies in Higher Education. Partner institutions are from France, Germany, Greece, Italy, Lithuania, Portugal and Slovenia: University of Orléans, University of Siegen, Hellenic Mediterranean University, Niccolò Cusano University, Vilnius Gediminas Technical University, Polytechnic Institute of Porto and University of Maribor. In 2022, two institutions joined the alliance: the Maria Curie-Skłodowska University from Poland and the University of Vigo from Spain. Also in 2022, an institution from Austria joined the alliance as an associate member: Carinthia University of Applied Sciences. This research book presents a selection of the research activities of ATHENA University's partners. It contains an overview of the research activities of individual members, a selection of the most important bibliographic works of members, peer-reviewed student theses, a descriptive list of ATHENA lectures and reports from individual working sections of the ATHENA project. The ATHENA Research Book provides a platform that encourages collaborative and interdisciplinary research projects by advanced and early career researchers