[en] In this report for Accreditation to Supervise Researches (HDR), the author, after his curriculum and an indication of his publications and registered patents, presents his research project. This presentation first comprises works performed for the development of a new instrument aimed at producing real-time images of the position of radioactive medicines which emit low energy β radiation. These works notably resulted in the production of the 'Beaver' instrument, a gaseous detector which notably comprises competitive PIM microstructures (Parallel Ionisation Multiplier). Then, he addresses the direct detection of dark matter with detectors containing Xenon operating in double liquid/gas phase. This detector is particularly interesting for very-low background noise works in the study of dark matter in the Universe, for example through the XENON100 and XENON1T experiments which have been enhanced by the introduction of the ReStoX unit which extends the experiment capacity. The last part addresses the development of 3-photon medical imagery, a new imagery technique at very low dose, in which Xenon plays a key role as it is the active heart of 3-photon cameras. The precise measurement of the ionisation signal is performed with MIMELI detectors which are presented. This builds up a new generation of cameras which can be very useful for nature observation.