Development of a Sensor Readout Integrated Circuit Towards a Contact Lens for Wireless Intraocular Pressure Monitoring

This design covers the design of an integrated circuit (IC) in support of the active contact lens project at Cal Poly. The project aims to monitor intraocular eye pressure (IOP) to help diagnose and treat glaucoma, which is expected affect 6.3 million Americans by 2050. The IC is designed using IBM’s 130 nm 8RF process, is powered by an on-lens thin film 3.8 V rechargeable battery, and will be fabricated at no cost through MOSIS. The IC features a low-power linear regulator that powers a current-starved voltage-controlled oscillator (CSVCO) used for establishing a backscatter communication link. Additional circuitry is included to regulate power to and from the battery. An undervoltage lockout circuit protects the battery from deep discharge damage. When recharging, a rectifier and a voltage regulator provides overvoltage protection. These circuit blocks are biased primarily using a 696 mV subthreshold voltage reference that consumes 110.5 nA

New Contact Sensorization Smart System for IoT e-Health Applications Based on IBC IEEE 802.15.6 Communications

[EN] This paper proposes and demonstrates the capabilities of a new sensorization system that monitors skin contact between two persons. Based on the intrabody communication standard (802.15.6), the new system allows for interbody communication, through the transmission of messages between di erent persons through the skin when they are touching. The system not only detects if there has been contact between two persons but, as a novelty, is also able to identify the elements that have been in contact. This sensor will be applied to analyze and monitor good follow-up of hand hygiene practice in health care, following the ¿World Health Organization Guidelines on Hand Hygiene in Health Care¿. This guide proposes specific recommendations to improve hygiene practices and reduce the transmission of pathogenic microorganisms between patients and health-care workers (HCW). The transmission of nosocomial infections due to improper hand hygiene could be reduced with the aid of a monitoring system that would prevent HCWs from violating the protocol. The cutting-edge sensor proposed in this paper is a crucial innovation for the development of this automated hand hygiene monitoring system (AHHMS).This research was funded by the Spanish Ministerio de Economia y Competitividad, grant number DPI2016-80303-C2-1-P.Hernández, D.; Ors Carot, R.; Capella Hernández, JV.; Bonastre Pina, AM.; Campelo Rivadulla, JC. (2020). New Contact Sensorization Smart System for IoT e-Health Applications Based on IBC IEEE 802.15.6 Communications. Sensors. 20(24):1-17. https://doi.org/10.3390/s20247097S117202

Development of an acoustic measurement system of the Modulus of Elasticity in trees, logs and boards

The objective of this Bachelor’s Thesis is to develop a portable electronic device capable of quantifying the stiffness of the wood of standing trees, logs and boards using non-destructive testing (NDT) by means of acoustic wave analysis. As an indicator of stiffness, the Modulus of Elasticity (MOE) is used, a standard figure in the industry. This way, wood from forestry can be characterized and classified for different purposes. This Thesis is part of LIFE Wood For Future, a project of the University of Granada (UGR) financed by the European Union’s LIFE programme. LIFE Wood For Future aims to recover the cultivation of poplar (populus sp.) in the Vega de Granada, by proving the quality of its wood through innovative structural bioproducts. Recovering the poplar groves of Granada would have great benefits for the Metropolitan Area: creation of local and sustainable jobs, improvement of biodiversity, and increase in the absorption of carbon dioxide in the long term, helping to reduce the endemic air pollution of Granada. This Final Degree Project has been developed in collaboration with the ADIME research group of the Higher Technical School of Building Engineering (ETSIE) and the aerospace electronics group GranaSat of the UGR. The goal of the developed device, named Tree Inspection Kit (or TIK), is to be an innovative, portable and easy-to-use tool for non-destructive diagnosis and classification of wood by measuring its MOE. TIK is equipped with the necessary electronics to quantify the Time of Flight (ToF) of an acoustic wave that propagates inside a piece of wood. In order to do this, two piezoelectric probes are used, nailed in the wood and separated a given distance longitudinally. The MOE can be derived from the propagation speed of the longitudinal acoustic wave if the density of the is known. For this reason, this device has the possibility of connecting a load cell for weighing logs or boards to estimate their density. It also has an expansion port reserved for future functionality. A methodology based on the Engineering Design Process (EDP) has been followed. The scope of this project embraces all aspects of the development of an electronic product from start to finish: conceptualization, specification of requirements, design, manufacture and verification. A project of this reach requires planning, advanced knowledge of signal analysis, electronics, design and manufacture of Printed Circuit Boards (PCB) and product design, as well as the development of a firmware for the embedded system, based on a RTOS. Prior to the design of the electronics, a Reverse Engineering process of some similar products of the competition is performed; as well as an exhaustive analysis of the signals coming from the piezoelectric sensors that are going to be used, and the frequency response characterization of the piezoelectric probes themselves. This project has as its ultimate goal the demonstration of the multidisciplinary knowledge of engineering, and the capacity of analysis, design and manufacturing by the author; his skill and professionalism in CAD and EDA software required for these tasks, as well as in the documentation of the entire process.El presente Trabajo de Fin de Grado tiene como objetivo el desarrollo de un dispositivo electrónico portátil capaz de cuantificar la rigidez de la madera de árboles en pie, trozas y tablas usando ensayos no destructivos (Non-Destructive Testing, NDT) por medio del análisis de ondas acústicas. Como indicador de la rigidez se usa el Módulo de Elasticidad (MOE), una figura estándar en la industria. Este TFG forma parte de LIFE Wood For Future, un proyecto de la Universidad de Granada (UGR) financiado por el programa LIFE de la Unión Europea. LIFEWood For Future tiene como objetivo recuperar el cultivo del chopo (populus sp.) en la Vega de Granada demostrando la viabilidad de su madera a través de bioproductos estructurales innovadores. Recuperar las choperas de Granada tendría grandes beneficios para la zona del Área Metropolitana: creación de puestos de trabajo locales y sostenibles, mejora de la biodiversidad, e incremento de la tasa de absorción de dióxido de carbono a largo plazo, contribuyendo a reducir la contaminación endémica del aire en Granada. Este Trabajo de Fin de Grado se ha desarrollado con la colaboración del grupo de investigación ADIME de la Escuela Técnica Superior de Ingeniería de Edificación (ETSIE) y el grupo de electrónica aeroespacial GranaSat de la UGR. El objetivo del dispositivo, denominado Tree Inspection Kit (TIK), es ser una herramienta innovadora, portátil y fácil de usar para el diagnóstico y clasificación no destructiva de la madera por medio de su MOE. TIK está dotado de la electrónica necesaria para medir el tiempo de tránsito (ToF) de una onda acústica que se propaga en el interior de una pieza de madera. Para ello, se utilizan dos sondas piezoeléctricas clavadas en la madera y separadas longitudinalmente una distancia conocida. De la velocidad de propagación de la onda longitudinal se puede derivar el MOE, previo conocimiento de la densidad del material. Por ello, este dispositivo cuenta con la posibilidad de conectarle una célula de carga y pesar trozas o tablas para estimar su densidad. También tiene un puerto de expansión reservado para funcionalidad futura. Se ha seguido una metodología basada en el Proceso de Diseño de Ingeniería (Engineering Design Process, EDP), abarcando todos los aspectos del desarrollo de un producto electrónico de principio a fin: conceptualización, especificación de requisitos, diseño, fabricación y verificación. Un proyecto de este alcance requiere de planificación, conocimientos avanzados de análisis de señales, de electrónica, de diseño y fabricación de Placas de Circuito Impreso (PCB) y de diseño de producto, así como el desarrollo de un firmware para el sistema empotrado, basado en un RTOS. Previo al diseño de la electrónica, se realiza un proceso de Ingeniería Inversa (Reverse Engineering) de algunos productos similares de la competencia; al igual que un exhaustivo análisis de las señales provenientes de los sensores piezoeléctricos que van a utilizarse y la caracterización en frecuencia de las propias sondas piezoeléctricas. Este proyecto tiene como fin último la demostración de los conocimientos multidisciplinares propios de la ingeniería y la capacidad de análisis, diseño y fabricación por parte del autor; su habilidad y profesionalidad en el software CAD y EDA requerido para estas tareas, así como en la documentación de todo el proceso.Unión Europe

Photovoltaic Energy Harvesting for Millimeter-Scale Systems

The Internet of Things (IoT) based on mm-scale sensors is a transformational technology that opens up new capabilities for biomedical devices, surveillance, micro-robots and industrial monitoring. Energy harvesting approaches to power IoT have traditionally included thermal, vibration and radio frequency. However, the achievement of efficient energy scavenging for IoT at the mm-scale or sub mm-scale has been elusive. In this work, I show that photovoltaic (PV) cells at the mm-scale can be an alternative means of wireless power transfer to mm-scale sensors for IoT, utilizing ambient indoor lighting or intentional irradiation of near-infrared (NIR) LED sources through biological tissue. Single silicon and GaAs photovoltaic cells at the mm-scale can achieve a power conversion efficiency of more than 17 % for silicon and 30 % for GaAs under low-flux NIR irradiation at 850 nm through the optimized device structure and sidewall/surface passivation studies, which guarantees perpetual operation of mm-scale sensors. Furthermore, monolithic single-junction GaAs photovoltaic modules offer a means for series-interconnected cells to provide sufficient voltage (> 5 V) for direct battery charging, and bypassing needs for voltage up-conversion circuitry. However, there is a continuing challenge to miniaturize such PV systems down to the sub mm-scale with minimal optical losses from device isolation and metal interconnects and efficient voltage up-conversion. Vertically stacked dual-junction PV cells and modules are demonstrated to increase the output voltage per cell and minimize area losses for direct powering of miniature devices for IoT and bio-implantable applications with low-irradiance narrowband spectral illumination. Dual-junction PV cells at small dimensions (150 µm x 150 µm) demonstrate power conversion efficiency greater than 22 % with more than 1.2 V output voltage under low-flux 850 nm NIR LED illumination, which is sufficient for batteryless operation of miniaturized CMOS IC chips. The output voltage of dual-junction PV modules with eight series-connected single cells is greater than 10 V while maintaining an efficiency of more than 18 %. Finally, I demonstrate monolithic PV/LED modules at the µm-scale for brain-machine interfaces, enabling two-way optical power and data transfer in a through-tissue configuration. The wafer-level assembly plan for the 3D vertical integration of three different systems including GaAs LED/PV modules, CMOS silicon chips, and neural probes is proposed.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163261/1/esmoon_1.pd

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

ESTCube-1 nanosatelliidi alams usteemide ja tarkvara disain ja karakteriseerimine

Väitekirja elektrooniline versioon ei sisalda publikatsiooneElektrilise päikesepurje tehnoloogia võimaldaks kosmosesondidel navigeerida planeetidevahelises ruumis ilma kütuseta, kasutades vaid päikesetuult ja elektrienergiat. Küll aga on tehnoloogiliselt keerukas päikesepurje purjetraadi väljakerimine, mis eeldab kosmosesondi pöörlemapanekut. 2013. aasta 7. mail maalähedasele orbiidile läkitatud tudengisatelliit ESTCube-1 oli esimene satelliit elektrilise päikesepurje katsetusmooduliga. Satelliit seati edukalt vajaliku pöörlemiskiirusega pöörlema, kuid purje väljakerimine ebaõnnestus mehaanilise tõrke tõttu katsetusmooduli motoriseeritud purjepoolis. ESTCube-1 pöörlemapanekut ja päikesepurje katsetusmooduli juhtimist võimaldasid satelliidi pardaarvuti ja seda ümbritsevad liidesed, mille arendamise ja valideerimise tulemustele keskendub antud väitekiri. Pardaarvuti kogus mõõdiseid satelliidi asendi anduritelt, juhtis magnetmähiseid ning lülitas missioonilasti purjepooli mootorit, purjepooli kõrgepinge toiteplokki ja elektronkiirgureid. Lisaks vahendas pardaarvuti pilte pardakaamerast ning salvestas mõõtmistulemusi satelliidi alamsüsteemidelt et need hiljem maajaamale edastada. Satelliidi kaheaastase eluea jooksul ei täheldatud missioonikriitilisi tõrkeid pardaarvuti ega selle liideste töös. ESTCube-1 missioon aitas edukalt tõsta elektrilise päikesepurje tehnoloogia komponentide valmidusastet tulevasteks missioonideks.Electrical solar wind sail (E-sail) technology would enable propellantless interplanetary navigation of space probes, using just solar wind and electricity. One of the main challenges of the technology is E-sail tether deployment, for which the space probe would be spun to a high angular rate. Launched on May 7th, 2013, the Estonian student satellite ESTCube-1 was the first spacecraft with an E-sail experiment payload. While the satellite was successfully spun to the spin rate necessary for the experiment, the motorised reel technology used on the payload proved immature for tether deployment. ESTCube-1 spin-up and payload control were enabled by the spacecraft on-board computer. This thesis is focused on the results of the development and in-orbit validation of the on-board computer and its interfaces to other related systems on the satellite. The on-board computer collected measurements from spacecraft attitude sensors, controlled its magnetic torquers, mediated camera images and stored telemetry from various subsystems for later transmission. The on-board computer also toggled the tether reel motor, electron emitters and controlled the high voltage supply for the E-sail tether. Throughout the two-year lifetime of the spacecraft, no mission-critical issues were encountered in the operation of the on-board computer or its interfaces. The ESTCube-1 mission successfully improved the technological readiness of E-sail components for future missions.https://www.ester.ee/record=b524281

Live Wire - A Low-Complexity Body Channel Communication System for Landmark Identification

This paper presents a robust simplex Body Channel Communication (BCC) system aimed at providing an interactive infrastructure solution for visually impaired people. Compared to existing BCC solutions, it provides high versatility, weara- bility and installability in an environment in a low complexity hardware-software solution. It operates with a ground referred transmitter (TX) and it is based on an asynchronous thresh- old receiver (RX) architecture. Synchronization, demodulation and packetizing and threshold control are completely software defined and implemented using MicroPython. The RX includes Bluetooth® (BT) radio connectivity and a cell-phone application provides push text-to-speech notifications to a smartphone. The hardware achieves a Packet Error Rate (PER) of ∼0.1 at 550 kHz pulse center frequency, Synchronized-On Off Keying (S- OOK) modulation and 1 kbps data rate, for an average current consumption of 44mA

Sensores passivos alimentados por transmissão de energia sem fios para aplicações de Internet das coisas

Nowadays, the Wireless Sensor Networks (WSNs) depend on the battery duration of the sensors and there is a renewed interest in creating a passive sensor network scheme in the area of Internet of Things (IoT) and space oriented WSN systems. The challenges for the future of radio communications have a twofold evolution, one being the low power consumption and, another, the adaptability and intelligent use of the available resources. Specially designed radios should be used to reduce power consumption, and adapt to the environment in a smart and e cient way. This thesis will focus on the development of passive sensors based on low power communication (backscatter) with Wireless Power Transfer (WPT) capabilities used in IoT applications. In that sense, several high order modulations for the communication will be explored and proposed in order to increase the data rate. Moreover, the sensors need to be small and cost e ective in order to be embedded in other technologies or devices. Consequently, the RF front-end of the sensors will be designed and implemented in Monolithic Microwave Integrated Circuit (MMIC).Atualmente, as redes de sensores sem fios dependem da duração da bateria e,deste modo, existe um interesse renovado em criar um esquema de rede de sensores passivos na área de internet das coisas e sistemas de redes de sensores sem fios relacionados com o espaço. Os desafios do futuro das comunicações de rádio têm uma dupla evolução, sendo um o baixo consumo de energia e, outro, a adaptação e o uso inteligente dos recursos disponíveis. Rádios diferentes dos convencionais devem ser usados para reduzir o consumo de energia e devem adaptar-se ao ambiente de forma inteligente e eficiente, de modo a que este use a menor quantidade de energia possível para estabelecer a comunicação. Esta tese incide sobre o desenvolvimento de sensores passivos baseados em comunicação de baixo consumo energético (backscatter) com recurso a transmissão de energia sem fios de modo a que possam ser usados em diferentes aplicações inseridas na internet das coisas. Nesse sentido, várias modulações de alta ordem para a comunicação backscatter serão exploradas e propostas com o objectivo de aumentar a taxa de transmissão de dados. Além disso, os sensores precisam de ser reduzidos em tamanho e económicos de modo a serem incorporados em outras tecnologias ou dispositivos. Consequentemente, o front-end de rádio frequência dos sensores será projetado e implementado em circuito integrado de microondas monolítico.Programa Doutoral em Engenharia Eletrotécnic