The work described in this thesis is concerned with self-localisation (automated estimation of sensor locations) and source-localisation (location of a target) using Wireless Sensor Networks (WSNs). The motivation for the research in this thesis is the on-line localisation of marmots from their alarm calls. The application requires accurate 3D self-localisation (within a small percentage of sensor spacing) as well as timely operation. Further challenges are added by the high data-rate involved: sensor nodes acquire data at a rate that is greater than the available network bandwidth. This data cannot be streamed over a multi-hop network, implying a need for data reduction through in-network event detection and local data compression or filtering techniques. The research approach adopted in this thesis combined simulation, emulation and real-life experimentation. Real-life deployment and experimentation highlighted problems that could not be predicted in controlled experiments or simulation. Emulation used data gathered from controlled, real-life experimentation to simulate proposed system refinements; this was sufficient to provide a proof-of-concept validation for some of the concepts developed. Simulation allowed the understanding of underlying theoretical behaviour without involving the complex environmental effects caused by real-life experimentation. This thesis details contributions in two distinct aspects of localisation: acoustic ranging and end-toend deployable acoustic source localisation systems. With regard to acoustic ranging and 3D localisation, two WSN platforms were evaluated: one commercially available, but heavily constrained (Mica2) and one custom-built for accurate localisation (Embedded Networked Sensing Box (ENSBox)). A new proof of concept platform for acoustic sensing (based on the Gumstix single-board computer) was developed by the author (including the implementation of a ranging mechanism), based on experiences with the platforms above. Furthermore, the literature was found to lack a specific procedure for evaluation and comparison of self-localisation algorithms from theoretical conception to real-life testing. Therefore, an evaluation cycle for self-localisation algorithms that encompassed simulation, emulation and real-life deployment was developed. With respect to source localisation, a hardware and software platform named VoxNet was designed and implemented.

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Developments in the field of optical sensing have seen the creation of a wide variety of new structures and materials. These include metamaterial sensors, which comprise of nanostructures with physical dimensions smaller than the wavelength of light. Two of the most widely researched metamaterial structures are the Split Ring Resonator (SRR) and fishnet. Both of these structures can be physically altered (in terms of geometry, material composition or periodicity) to exhibit plasmonic resonances at frequencies as far as the visible regime. The near-infrared frequency range is of particular interest with regard to optical sensing as many molecular absorption bands can be found here. This thesis studies the effectiveness of different designs of optical sensors and the fabrication techniques used to produce them. By changing the dimensions and constituent metal of SRRs, their resonance response is analysed and parameters such as the Quality factor (Q-factor) obtained. The sensitivity of a single gap SRR to the presence of a thin film and localised block of Polymethyl methacrylate (PMMA) is experimentally measured. By changing the position of the localised PMMA block, it can be used as a material probe for the sensor, enabling the areas of greatest sensitivity to be determined. The sensitivity of the SRR is found to greatly depend on the polarisation of the incident electric field with respect to the structure, varying between 143 nm/RIU and 612 nm/RIU when PMMA is positioned at the gap in the ring. Complementary simulations offer additional insight into the behaviour of the structure at a range of frequencies. In addition to plasmonic structures, the fabrication and characterisation of a polymer photonic biosensor is also studied. This sensor utilises a distributed Bragg reflector (DBR) cavity adjacent to a rib waveguide to create a narrow stop-band that can potentially be used in the sensing of specifically targeted biological analytes. For optical sensors to make a transition from research environment to commercial application, the costly fabrication techniques associated with the research and development of nanostructures need to be avoided. Nanoimprint lithography (NIL) offers multiple benefits in terms of cost, fabrication time and the patterning of large areas and is well suited to the commercial sector. NIL has been extensively used throughout the work detailed in this thesis to pattern SRRs, fishnets and polymer sensors.

This research project has investigated the light fastness of ink jet and electrophotographic printed materials by the means of an extensive accelerated and natural ageing test programme. The effect of visible radiation of different wavebands on the deterioration of a selection of ink jet printed materials has also been assessed. The findings of the research indicate that all of the ink jet printed materials tested are sensitive to light and should not therefore, be put on permanent display. Most of the ink jet printed samples exhibited greater light sensitivity to the shorter wavelengths of the visible spectrum, than the longer wavelengths, with damage decreasing as wavelength increases. This relationship was not evident with the cyan and blue printed samples, which showed that their light sensitivity was determined by the spectral absorption characteristics of the printed patch. Some of the ink jet printed materials produced erratic fading rates on exposure to light. This phenomenon was attributed to either the occurrence of photochromism or the disintegration of the dye particles in the ink, but further testing needs to be conducted to gain a better understanding of this reaction. Other factors also influenced the light fastness of the ink jet materials, such as the type of paper employed for printing, ink concentration and ink combination. The electrophotographic printed materials were found to be more stable to light, although the yellow toner from some of the systems would show noticeable fading after approximately 65 to 325 years on permanent display (at 50 lux for eight hours per day). A range of basic conservation treatments was also been investigated and the results indicated that ink jet print materials are very sensitive to all forms of aqueous treatments. Finally, thermal/dark ageing has been performed on the digital printed papers employed in this investigation. The conclusion is that all of the papers are prone to yellowing in storage.

L’objectif de cette thèse était d’explorer le potentiel des biocapteurs à base de transistors à 1 électron. Depuis l’invention de l’électrode de verre il y a plus de 100 ans, la réponse monotone du potentiel de surface avec le pH est devenue universelle. Aussi, il est bien connu que les mesures de la concentration en ions dans des solutions complexes, de grande importance pour le domaine biomédical, requière des membranes sélectives aux ions. En utilisant ces transistors nanométriques, nous montrons une rupture dans ces concepts avec l’observation d’une réponse en U au pH et la mesure sélective des cations Na+, K+, Ca2+ et Mg2+ dans le sérum sanguin, sans avoir recours aux membranes sélectives. Par ailleurs, les ions divalents ont été mesurés avec une sensibilité deux fois supérieure à la limite de Nernst. Les équations proposées, à l’origine d’une nouvelle méthode pour les mesures sélectives d’ions, peuvent-être étendues à la mobilité électrophorétique. Nous suggérons que ces nanotransistors 0D devraient également permettre des études biomimétiques de la compensation de charge des protéines. Nous montrons enfin que ces composants peuvent être intégrés sur un laboratoire sur puce en PDMS de 1.5 mm x 1.5 mm, qui promet un système de diagnostic sanguin peu couteux et très intégré. / The aim of this thesis was to explore the potential of 0D nanotransistor biosensors. Since the invention of glass electrode a century ago, the monotonic decrease of oxides surface potential with pH has become universal. Also, it is well known that the measurement of ions concentration in complex solutions, of great importance for biomedical field, requires ion-selective membranes. Using these nanometric transistor biosensors, we report a rupture in these concepts with the observation of a U-shape pH response and the selective measurement of Na+, K+, Ca2+ and Mg2+ cations in blood serum, without falling back on selective membranes. In addition, divalent ions were measured with a sensitivity twice of that of Nernst limit. Proposed equations, at the origin of the new method for ion selective measurements, can be extended to the electrophoretic mobility. We also suggest that 0D nanotransistor biosensors are a relevant test bed for biomimetic studies of proteins charge compensation. We finally show that these devices can be ultimately integrated on a mm² PDMS-based lab-on chip, which promises for a cheap and small blood diagnosis system.

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Au cœur des métamorphoses esthétiques de la littérature africaine d’expression française, il apparaît une forme particulière d’écriture qui rompt avec le récit terne et linéaire des écrivains de la période post-coloniale. Aussi, cette nouvelle manière d’écrire donne naissance à une nouvelle génération d’écrivains francophones qui proposent aux lecteurs une littérature plus crue, plus sensuelle voire plus sexuelle. Celle-ci se donne désormais pour objectif de critiquer les mœurs sociales à travers la description de divers personnages de romans en proie à la complexité de leur monde intime. Cette nouvelle conception romanesque nous inscrit dans une tendance littéraire actuelle visant à lire l’universel dans l’intimité. De fait, la particularité de notre thèse réside dans sa capacité à amener le lecteur à voir le lien qui pourrait exister entre l’écriture du corps et la quête de l’identité dans la littérature contemporaine d’Afrique francophone. Ceci serait en effet possible à travers l'analyse psychocritique de certaines œuvres des auteurs qui la compose, comme celles de l'écrivain franco-togolais Sami TCHAK. Ces investigations conduisent ainsi le lecteur à se demander de quelle manière l'écriture du corps, à travers celle de la sexualité, peut véhiculer un discours capable de permettre au sujet écrivant de se révéler à lui-même. Ce choix esthétique de la transgression, aussi bien sur le fond que sur la forme, semble être en réalité un prétexte à la reconfiguration stylistique de la littérature africaine contemporaine par cette nouvelle génération d'écrivains. / In the heart of the aesthetic transformations of African literature of French expression, a special form of writing that breaks with the dull and linear narrative of the writers of the post-colonial period appears. Also, this new way of writing gives way to a new generation of francophone writers who offers readers a more raw, more sensual, more sexual literature. It is now intended to criticize social mores through the description of various characters from novels which are prey to the complexity of their intimate world. This new form of writing has enrolled us in a current literary trend that allows to introduce the universal character in the intimacy. In fact, the peculiarity of our thesis lies in its ability to lead the reader to perceive the link that may exist between the writing of the body and the quest for identity in contemporary literature of francophone Africa. This would be possible through the analysis of psychological critics of some literary works such as those of the Franco-Togolese writer Sami TCHAK. This research leads the reader to wonder how the writing of the body, through that of sexuality, can convey a literary discourse capable of allowing the writer to have a better understanding of himself. This aesthetic choice of transgression seems to actually be a pretext for the stylistic reconfiguration of contemporary African literature thanks to this new generation of writers.