Perylene Diimide acceptors: Fabrication and characterization of electron-only, hole-only devices and solar cells

The thrust towards energy conservation and reduced environmental footprint has fueled intensive research for alternative low cost sources of renewable energy. Organic photovoltaic cells (OPVs), with their low fabrication costs, easy processing and flexibility, represent a possible viable alternative. Perylene diimides (PDIs) are promising electron-acceptor candidates for bulk heterojunction (BHJ) OPVs, as they combine higher absorption and stability with tunable material properties, such as solubility and position of the lowest unoccupied molecular orbital (LUMO) level. A prerequisite for trap free electron transport is for the LUMO to be located at a level deeper than 3.7 eV since electron trapping in organic semiconductors is universal and dominated by a trap level located at 3.6 eV. Although the mostly used fullerene acceptors in polymer:fullerene solar cells feature trap-free electron transport, low optical absorption of fullerene derivatives limits maximum attainable efficiency. In this thesis, we try to get a better understanding of the electronic properties of PDIs, with a focus on charge carrier transport characteristics and the effect of different processing conditions such as annealing temperature and top contact (cathode) material. We report on a commercially available PDI and three PDI derivatives as acceptor materials, and its blends with MEH-PPV (Poly[2-methoxy 5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) and P3HT (Poly(3-hexylthiophene-2,5-diyl)) donor materials in single carrier devices (electron-only and hole-only) and in solar cells. Space-charge limited current measurements and modelling of temperature dependent J-V characteristics confirmed that the electron transport is essentially trap-free in such materials. Different blend ratios of P3HT:PDI-1 (1:1) and (1:3) show increase in the device performance with increasing PDI-1 ratio. Furthermore, thermal annealing of the devices have a significant effect in the solar cells that decreases open-circuit voltage (Voc) and fill factor FF, but increases short-circuit current (Jsc) and overall device performance. Morphological studies show that over-aggregation in traditional donor:PDI blend systems is still a big problem, which hinders charge carrier transport and performance in solar cells.

Algorithms for time series clustering applied to biomedical signals

Thesis submitted in the fulfillment of the requirements for the Degree of Master in Biomedical Engineering

Gold nanoparticle to antibody conjugates for diagnosis applications: molecular interactions and immunoassay development

Thesis for the Master degree in Structural and Functional Biochemistry

Purification of complex biopharmaceuticals with new processes, advanced analytics and computer-aided process design tools

Dissertação para obtenção do Grau de Mestre em Biotecnologia

Service-oriented infrastructure to support the control, monitoring and management of a shop floor system

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores

Microelectromechanical systems. Fabrication and characterization of microcantilevers

Microelectromechanical systems (MEMS) technologies can be used to produce from the simplest structures to the most complex devices and systems. Due to their many applications in various fields, MEMS have turned into one of the most researched areas in microtechnology. In this context, this project was developed in an attempt to produce one of most used structures in MEMS sensing devices - microcantilevers. Several microfabrication techniques were combined to fabricate this type of structures on the top layer of silicon of a silicon-on-insulator (SOI) wafer. After the microcantilevers had been successfully created, an experiment was set up to verify the microcantilevers ability to bend. Here, a voltage was applied between the top and bottom layers of silicon of the SOI wafer. It was then observed that the microcantilevers were deflected all the way to the bottom silicon layer by the electrostatic force acting between them, given that a current was detected when a certain value of applied voltage was reached.

Engineering of metal oxide nanoparticles for application in electrochemical devices

The growing demand for materials and devices with new functionalities led to the increased inter-est in the field of nanomaterials and nanotechnologies. Nanoparticles, not only present a reduced size as well as high reactivity, which allows the development of electronic and electrochemical devices with exclusive properties, when compared with thin films. This dissertation aims to explore the development of several nanostructured metal oxides by sol-vothermal synthesis and its application in different electrochemical devices. Within this broad theme, this study has a specific number of objectives: a) research of the influence of the synthesis parameters to the structure and morphology of the nanoparticles; b) improvement of the perfor-mance of the electrochromic devices with the application of the nanoparticles as electrode; c) application of the nanoparticles as probes to sensing devices; and d) production of solution-pro-cessed transistors with a nanostructured metal oxide semiconductor. Regarding the results, several conclusions can be exposed. Solvothermal synthesis shows to be a very versatile method to control the growth and morphology of the nanoparticles. The electrochromic device performance is influenced by the different structures and morphologies of WO3 nanoparticles, mainly due to the surface area and conductivity of the materials. The dep-osition of the electrochromic layer by inkjet printing allows the patterning of the electrodes without wasting material and without any additional steps. Nanostructured WO3 probes were produced by electrodeposition and drop casting and applied as pH sensor and biosensor, respectively. The good performance and sensitivity of the devices is explained by the high number of electrochemical reactions occurring at the surface of the na-noparticles. GIZO nanoparticles were deposited by spin coating and used in electrolyte-gated transistors, which promotes a good interface between the semiconductor and the dielectric. The produced transistors work at low potential and with improved ON-OFF current ratio, up to 6 orders of mag-nitude. To summarize, the low temperatures used in the production of the devices are compatible with flexible substrates and additionally, the low cost of the techniques involved can be adapted for disposable devices.

Using an LED as a sensor and visible light communication device in a smart illumination system

The need for more efficient illumination systems has led to the proliferation of Solid-State Lighting (SSL) systems, which offer optimized power consumption. SSL systems are comprised of LED devices which are intrinsically fast devices and permit very fast light modulation. This, along with the congestion of the radio frequency spectrum has paved the path for the emergence of Visible Light Communication (VLC) systems. VLC uses free space to convey information by using light modulation. Notwithstanding, as VLC systems proliferate and cost competitiveness ensues, there are two important aspects to be considered. State-of-the-art VLC implementations use power demanding PAs, and thus it is important to investigate if regular, existent Switched-Mode Power Supply (SMPS) circuits can be adapted for VLC use. A 28 W buck regulator was implemented using a off-the-shelf LED Driver integrated circuit, using both series and parallel dimming techniques. Results show that optical clock frequencies up to 500 kHz are achievable without any major modification besides adequate component sizing. The use of an LED as a sensor was investigated, in a short-range, low-data-rate perspective. Results show successful communication in an LED-to-LED configuration, with enhanced range when using LED strings as sensors. Besides, LEDs present spectral selective sensitivity, which makes them good contenders for a multi-colour LED-to-LED system, such as in the use of RGB displays and lamps. Ultimately, the present work shows evidence that LEDs can be used as a dual-purpose device, enabling not only illumination, but also bi-directional data communication.

Augmenting spaces and creating interactive experiences using video camera networks

This research addresses the problem of creating interactive experiences to encourage people to explore spaces. Besides the obvious spaces to visit, such as museums or art galleries, spaces that people visit can be, for example, a supermarket or a restaurant. As technology evolves, people become more demanding in the way they use it and expect better forms of interaction with the space that surrounds them. Interaction with the space allows information to be transmitted to the visitors in a friendly way, leading visitors to explore it and gain knowledge. Systems to provide better experiences while exploring spaces demand hardware and software that is not in the reach of every space owner either because of the cost or inconvenience of the installation, that can damage artefacts or the space environment. We propose a system adaptable to the spaces, that uses a video camera network and a wi-fi network present at the space (or that can be installed) to provide means to support interactive experiences using the visitor’s mobile device. The system is composed of an infrastructure (called vuSpot), a language grammar used to describe interactions at a space (called XploreDescription), a visual tool used to design interactive experiences (called XploreBuilder) and a tool used to create interactive experiences (called urSpace). By using XploreBuilder, a tool built of top of vuSpot, a user with little or no experience in programming can define a space and design interactive experiences. This tool generates a description of the space and of the interactions at that space (that complies with the XploreDescription grammar). These descriptions can be given to urSpace, another tool built of top of vuSpot, that creates the interactive experience application. With this system we explore new forms of interaction and use mobile devices and pico projectors to deliver additional information to the users leading to the creation of interactive experiences. The several components are presented as well as the results of the respective user tests, which were positive. The design and implementation becomes cheaper, faster, more flexible and, since it does not depend on the knowledge of a programming language, accessible for the general public.

Online strategies for offline business the case of Millennials and shopping centrs (Sonae Sierra)

The project, conducted within a direct research internship at Sonae Sierra, aims to propose innovative digital approaches for Shopping Centres (SC) to deal successfully with millennial consumer behavior concerning digital devices and online content in relation to shopping. An online survey followed by a focus group were conducted for this purpose. Results show a demand for specific digital services created by a SC and that their perception depends highly on gender of millennials. Moreover it´s a cohort seeking for personalized content, providing emotional or functional benefit. Consequently a SC must deliver services, as presented in this work satisfying those needs.

Bio-inspired anatomy for autonomous DPWS-compliant automation components

Dissertação apresentada na Faculdade de Ciências e Engenharia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

Percepção do estado de saúde de doentes com anticoagulação oral

RESUMO - O aumento da incidência das doenças crónicas representa um desafio enorme para todos os Sistemas de Saúde, pelo que a assistência de Saúde a doentes crónicos se tornou num problema das sociedades ocidentais. Os países mais pobres são os que mais sofrem, embora nos países desenvolvidos também se verifique um aumento notável das doenças crónicas. Estima-se que estas representem mais de 60% do total das doenças mundiais no ano 2020 (WHO, 2001). A adaptação dos actuais modelos de saúde aos doentes crónicos não atingiu os objectivos, o que conduziu a que, de há alguns anos a esta parte, se procure alternativas mais eficazes e eficientes. Uma das pressões do mercado que se fazem sentir será caracterizada por uma maior aposta na Promoção da Saúde e Prevenção da doença. O conceito de “Saúde” migrou de “não existência de doença” para “Bem-estar Físico e Psicológico”. Desta forma, o foco dos cuidados de saúde teve que ser adaptado, o que conduziu a uma situação em que o âmbito da prestação de cuidados de saúde é um contínuo de serviços que vai desde a promoção da saúde, medicina preventiva e medicina curativa aos cuidados continuados e cuidados paliativos. As tecnologias de informação e comunicação desempenharão um importante papel nesta tendência, permitindo estabelecer ligações contínuas entre os consumidores e prestadores de cuidados de saúde. Por outro lado, as potencialidades da Internet, das comunicações móveis, dispositivos portáteis e do instrumental electrónico, tornam-se evidentes no desenvolvimento de serviços de e-Saúde: para monitorização, seguimento e controlo dos doentes extra hospitalar - serviços estes centrados no doente. O objectivo geral do presente estudo consiste no desenho de um projecto de investigação para posterior avaliação da percepção do estado de saúde dos doentes seguidos na consulta de hipocoagulação do Hospital de Santa Marta. Devido à escassez de investigação na temática deste trabalho em Portugal, procedeu-se a um trabalho exploratório, descritivo, de carácter comparativo e enquadrado na abordagem quantitativa. O campo de análise consiste em comparar doentes que fazem anticoagulação oral, seguidos na consulta de cardiologia (consulta convencional), com os doentes seguidos no programa Airmed (através das comunicações móveis). 4 Para avaliação da percepção do estado de saúde foi utilizado o questionário SF-36.----ABSTRACT - The increasing incidence of chronic diseases represents an enormous challenge to the Health Systems and on cause of that, the Health Assistance to chronic patients became a concern of the Occidental society. The Countries with lower economical resources are the ones that suffers the most, but also the Developed countries have a noticeable increase of chronic diseases. It is estimated these will represent over 60% of total diseases world wide in 2020 (WHO,2001). The adaptation of the actual Health Models to chronic patients did not achieved it’s goals, what leaded to look for more effective and efficient alternatives. One of the more sensitive market pressure factor is to look for a better Health Promotion and Disease Prevention. The concept of “Health” merged from “Disease absence” to “Physic and Psychic Wellness”. In this way the Health Care focus had to be adapted, what drove to a status where the scope of the Health care is a continuum of services that goes from the Health Promotion, Preventive and Curative to Continued and Palliative Medical Care. The Information and Communication Technologies will play a crucial role in this trend, allowing to establish continued connections between patients and Health Care providers. In parallel the potential of the Internet, mobile communications, portable devices and electronic instruments became evident to deploy e-Health services: to monitor, follow-up and control of patients outside the Hospital. The overall objective of the present study is an Investigation Project Design to further evaluate the health status perception of the patients followed in the consultation for Hypocoagulation in the “Hospital de Santa Marta”. Due to lack of investigation in this thematic, in Portugal, this study is developed in an exploratory way, descriptive, comparative, within a scope of a quantified approach. The analysis field consists on comparing patients prescribed with oral anticoagulants and followed-up at the

Mobile persuasive interfaces for public ambient displays

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Informática

Evaluation of thermometers for ear temperature measurement at the wards in a university hospital

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

UsaGame – A new methodology to support user- centered design of touchscreen game applications

Dissertação para Obtenção do Grau de Mestre em Engenharia e Gestão Industrial