Avec le développement rapide des technologies sans fil modernes et la miniaturisation des antennes et des systèmes électriques, l'emploi des antennes à l'intérieur du corps humain pour le suivi thérapeutique est devenu possible. Des batteries permettent d'alimenter ces antennes ; la réduction de la consommation de puissance implique l'augmentation de la durée de vie de circuits ingérables. Le corps humain, qui a une conductivité non nulle, n'est pas un milieu idéal pour la transmission des ondes RF à cause de l'atténuation liée aux propriétés diélectriques des tissus biologiques. Cependant, les tissus humains ne perturbent pas le champ magnétique car celui-ci dépend de la perméabilité du milieu qui est égale à un dans le corps humain. Bien que la puissance du champ magnétique décroisse avec l'exposant six de la distance, la technique utilisant les communications par induction magnétique en champ proche a été adoptée dans cette étude pour concevoir une liaison sans fil à faible portée à travers le corps humain. Durant ces travaux de thèse, après une caractérisation détaillée de la bobine d'émission située à l'intérieur du corps humain et de la bobine de réception localisée à sa surface, nous avons mis en place un bilan de liaison pour contribuer à l'amélioration du transfert de puissance dans ce milieu dissipatif. Un modèle analytique, déterminant les facteurs qui peuvent affecter le bilan de liaison par induction magnétique, a été vérifié à travers les simulations et les mesures. La variation de la position et de l'orientation de l'antenne ingérable ont été prises en compte pour évaluer la réponse de couplage entre la bobine émettrice et la bobine réceptrice. Les résultats obtenus constituent un pas en avant vers de futures recherches sur la conception de antennes dans les milieux dissipatifs et en particulier le corps humain / With the rapid growth of wireless technology and the miniaturization of modern antennas and electrical systems, the use of antennas inside the human body for therapeutic monitoring became possible. Batteries are used to supply these antennas; reducing the power consumption allows to increase the lifetime of ingestible systems. The human body, which has non-zero conductivity, is not an ideal environment for the transmission of RF waves because of the attenuation due to the dielectric properties of biological tissues. However, the human tissues do not disrupt the magnetic field as it depends on the permeability of the medium which is equal to one in the human body. Although the magnetic field power decreases with the distance exponent six, the technique using near-field magnetic induction communications was adopted in this study to design a short range wireless link through the human body. In this thesis, after a detailed characterization of the transmitting coil antenna located inside the human body and the receiving coil placed on its surface, we have implemented a link budget to contribute to the improvement of power transfer in the dissipative medium. An analytical model, identifying factors that can affect the link budget by magnetic induction, has been verified through simulations and measurements. The variation of the position and the orientation of the ingestible antenna were taken into account to evaluate the coupling response between the transmitting coil and the receiving coil. The results are a step toward future research on the design of antennas in dissipative media, in particular the human body

<p dir="ltr">The gastrointestinal tract harbors a diverse range of microorganisms, collectively constituting the gut microbiome. <a href="" target="_blank">The maintenance of a symbiotic relationship between the host and these microorganisms is essential to gastrointestinal health. Disruption of the ecological balance within the gut microbiome can result in discomfort or pathological conditions.</a> <a href="" target="_blank">This dissertation explores these alterations within the gastrointestinal tract as potential indicators for specific gastrointestinal diseases.</a> <a href="" target="_blank">In pursuit of this, I collaborated with others to develop a smart ingestible capsule that offers a non-invasive method for enhancing the effectiveness of differential diagnosis and treatment strategies for Inflammatory Bowel Disease (IBD). </a>My contributions encompassed conducting <i>in vitro</i> protein sampling and extraction experiments, as well as enteric coating dissolution tests. Following thorough characterization of the capsule, I advanced to <i>ex vivo</i> sampling experiments. As a proof of concept, the capsule's sampling capabilities have been rigorously validated both <i>in vitro</i> and <i>ex vivo</i> using calprotectin, a key biomarker for monitoring and managing IBD. Future research may explore integrating this technology with other sensors for diverse chemical and gas sensing capabilities, aiming to refine the differential diagnostics of Irritable Bowel Syndrome (IBS) and IBD.</p><p dir="ltr">Simultaneously, the potential transmission of pathogenic microorganisms from the gastrointestinal tract to the environment through fecal matter can lead to substantial public health implications if adequate surveillance is not in place. These pathogens can contaminate water and food sources from various origins, exacerbating the problem. Furthermore, conventional laboratory-based assays, while effective, have extensive turnaround times and require skilled scientists to operate them. In response to this challenge, I have undertaken the development of point-of-care assays, aiming to streamline the detection of fecal contamination. This innovation is designed to mitigate the limitations associated with traditional methods by offering a more rapid and user-friendly approach. The primary objective is to enhance the accessibility of these assays, enabling on-site personnel with varying levels of expertise to utilize them effectively. Through the widespread adoption of these point-of-care assays, the overarching goal is to ensure the consistent provision of safe and reliable water and food supplies to the public.</p>