An Optoelectronic Stimulator for Retinal Prosthesis

Retinal prostheses require the presence of viable population of cells in the inner retina. Evaluations of retina with Age-Related Macular Degeneration (AMD) and Retinitis Pigmentosa (RP) have shown a large number of cells remain in the inner retina compared with the outer retina. Therefore, vision loss caused by AMD and RP is potentially treatable with retinal prostheses. Photostimulation based retinal prostheses have shown many advantages compared with retinal implants. In contrary to electrode based stimulation, light does not require mechanical contact. Therefore, the system can be completely external and not does have the power and degradation problems of implanted devices. In addition, the stimulating point is flexible and does not require a prior decision on the stimulation location. Furthermore, a beam of light can be projected on tissue with both temporal and spatial precision. This thesis aims at fi nding a feasible solution to such a system. Firstly, a prototype of an optoelectronic stimulator was proposed and implemented by using the Xilinx Virtex-4 FPGA evaluation board. The platform was used to demonstrate the possibility of photostimulation of the photosensitized neurons. Meanwhile, with the aim of developing a portable retinal prosthesis, a system on chip (SoC) architecture was proposed and a wide tuning range sinusoidal voltage-controlled oscillator (VCO) which is the pivotal component of the system was designed. The VCO is based on a new designed Complementary Metal Oxide Semiconductor (CMOS) Operational Transconductance Ampli er (OTA) which achieves a good linearity over a wide tuning range. Both the OTA and the VCO were fabricated in the AMS 0.35 µm CMOS process. Finally a 9X9 CMOS image sensor with spiking pixels was designed. Each pixel acts as an independent oscillator whose frequency is controlled by the incident light intensity. The sensor was fabricated in the AMS 0.35 µm CMOS Opto Process. Experimental validation and measured results are provided

A neural network based intelligent predictive sensor for cloudiness, solar radiation and air temperature

Accurate measurements of global solar radiation and atmospheric temperature, as well as the availability of the predictions of their evolution over time, are important for different areas of applications, such as agriculture, renewable energy and energy management, or thermal comfort in buildings. For this reason, an intelligent, light-weight and portable sensor was developed, using artificial neural network models as the time-series predictor mechanisms. These have been identified with the aid of a procedure based on the multi-objective genetic algorithm. As cloudiness is the most significant factor affecting the solar radiation reaching a particular location on the Earth surface, it has great impact on the performance of predictive solar radiation models for that location. This work also represents one step towards the improvement of such models by using ground-to-sky hemispherical colour digital images as a means to estimate cloudiness by the fraction of visible sky corresponding to clouds and to clear sky. The implementation of predictive models in the prototype has been validated and the system is able to function reliably, providing measurements and four-hour forecasts of cloudiness, solar radiation and air temperature

Magnetosensitive e-skins for interactive electronics

The rapid progress of electronics and computer science in the last years has brought humans and machines closer than ever before. Current trends like the Internet of Things and artificial intelligence are closing the gap even further, by providing ubiquitous data processing and sensing. As this ongoing revolution advances, novel forms of human-machine interactions are required in an ever more connected world. A crucial component to enable these interactions is the field of flexible electronics, which aims to establish a seamless link between living and artificial entities using electronic skins (e-skins). E-skins combine the functionality of commercial electronics with the soft, stretchable and biocompatible characteristics of human skin or tissue. Until lately, the focus had been to replicate the standard functions associated with human skin, such as, temperature, pressure and chemical detection. Yet, recent developments have also introduced non-standard sensing capabilities like magnetic field detection to create the field of magnetosensitive e-skins. The addition of a supplementary information channel—an electronic sixth sense—has sparked a wide range of applications in the fields of cognitive psychology and human-machine interactions. In this thesis, we expand the concept of magnetosensitive e-skins to include the notion of directionality, which utilizes the full interaction potential of the magnetic field vector. Also, we introduce the use of flexible magnetoelectronics in virtual/augmented reality and human-computer interfaces. Three main results are attained in the course of this work: (i) we first demonstrate how magnetosensitive e-skins can be used as humanmachine interfaces driven by permanent magnet sources in the range of 5 mT. (ii) Building upon this milestone, we realize the first magnetosensitive e-skins which are driven by the earth’s magnetic field of 50 μT. (iii) We fabricate magnetosensitive e-skins which push the detection limit below 1 μT. The magnetosensitive e-skins in this work open exciting possibilities for sensory substitution experiments and sensory processing disorder therapies. Futhermore, for human-machine interactions, they provide a new interactive platform for touchless and gestural control in virtual and augmented reality scenarios beyond the limitations of optics-based systems.Der rasante Fortschritt der Elektronik und der Informatik in den letzten Jahren hat Mensch und Maschine nähergebracht als je zuvor. Aktuelle Trends wie das Internet der Dinge und künstliche Intelligenz schließen die Lücke noch weiter, indem sie eine allgegenwärtige Datenverarbeitung und -erfassung ermöglichen. Mit fortschreitender Revolution sind neue Formen der Mensch-Maschine-Interaktion in einer immer vernetzter werdenden Welt erforderlich. Eine entscheidende Komponente, um diese Interaktionen zu ermöglichen, ist das Gebiet der flexiblen Elektronik, das darauf abzielt, mithilfe elektronischer Häute (e-skins) eine nahtlose Verbindung zwischen lebenden und künstlichen Entitäten herzustellen. E-skins verbinden die Funktionalität kommerzieller Elektronik mit den weichen, dehnbaren und biokompatiblen Eigenschaften menschlicher Haut oder menschlichen Gewebes. Bis vor kurzem lag der Schwerpunkt auf der Nachbildung der mit der menschlichen Haut verbundenen Standardfunktionen wie Temperatur-, Druck- und Chemikalienerkennung. Jüngste Entwicklungen haben jedoch auch nicht standardmäßige Erfassungsfähigkeiten wie die Magnetfelderkennung eingeführt, um das Feld magnetoempfindlicher e-skins zu erzeugen. Die Hinzufügung eines zusätzlichen Informationskanals - eines elektronischen sechsten Sinns - hat eine breite Palette von Anwendungen auf den Gebieten der kognitiven Psychologie und der Mensch-Maschine-Interaktionen ausgelöst. In dieser Arbeit erweitern wir das Konzept der magnetoempfindlichen e-skins um den Begriff der Richtwirkung, bei dem das volle Wechselwirkungspotential des Magnetfeldvektors genutzt wird. Außerdem führen wir die Verwendung flexibler Magnetoelektronik in der virtuellen Realität / erweiterten Realität und in Mensch-Computer-Schnittstellen ein. Im Verlauf dieser Arbeit werden drei Hauptergebnisse erzielt: (i) Wir demonstrieren erstmals, wie magnetoempfindliche e-skins als Mensch-Maschine-Schnittstellen verwendet werden können, die von Permanentmagnetquellen im Bereich von 5 mT angetrieben werden. (ii) Aufbauend auf diesem Meilenstein realisieren wir die ersten magnetoempfindlichen e-skins, die vom Erdmagnetfeld von 50 μT angetrieben werden. (iii) Wir fertigen magnetoempfindliche e-skins, bei denen die Nachweisgrenze unter 1 μT liegt. Die magnetoempfindlichen e-skins in dieser Arbeit eröffnen aufregende Möglichkeiten für sensorische Substitutionsexperimente und Therapien bei sensorischen Verarbeitungsstörungen. Darüber hinaus bieten sie für die Mensch-Maschine-Interaktion eine neue interaktive Plattform für die berührungslose und gestische Steuerung in virtuellen und Augmented Reality-Szenarien, die über die Grenzen optikbasierter Systeme hinausgehen

Sensors and Biosensors Related to Magnetic Nanoparticles

This book describes interesting examples of magnetic materials with magnetic nanoparticles or compact devices using composites with nanoparticles, including new engineering solutions and theoretical contributions on the magnetic biosensing of soft matter composites. Authors from different countries formed international team of experts sharing 10 contributed papers, 1 feature paper, and 1 topical review

Lidar Mapping of Near-Surface Aerosol Fields

Near-surface atmospheric measurements over urban or industrial areas aimed at assisting the air-quality monitoring attain increasing societal significance due to the strong and direct impact of aerosol pollutions in the low troposphere on the human health. In this chapter, we present experimental results on lidar mapping of aerosol fields over the city of Sofia (Bulgaria), its suburbs and adjacent towns and villages, obtained during an extensive 7-month experimental campaign in 2015. The measurements are conducted by scanning observation zones in horizontal and vertical directions using lidar systems developed at the Institute of Electronics, Bulgarian Academy of Sciences. Based on the aerosol backscattering profiles retrieved at different azimuth or elevation angles, two-dimensional color-coded sector maps of the near-surface aerosol density are obtained, overlaid on the topological map of the Sofia region. The analysis of the lidar maps shows good correlation between the aerosol density distribution and the locations of important sources of aerosol pollutions in the zones of observation, such as city streets with intense traffic, industrial facilities, densely populated residential districts, etc. The results reported demonstrate that aerosol lidar mapping could be regarded as an effective approach for accurate and reliable determination of the density, spatial distribution, and temporal dynamics of close-to-ground aerosols, covering broad urban areas. Possibilities of incorporating synergistically lidar mapping technologies into municipal air-quality monitoring systems are also discussed