Highly-sensitive energy detectors are a frontier and challenging R&D topic. Cryogenic microcalorimeters are currently the best detector candidates for X-rays, electrons, nuclear recoil, etc. The future direct neutrino mass determination international and funded experiments are using this technology. While the microcalorimeter operating principle is simple, the full detector performance and optimization, is not trivial, and still currently being under R&D. The theoretical predictions for its optimum performance has not been experimental reached and the modelling of such a behaviour is a state-of-the-art complex fundamental superconductivity topic, but also a key element for the detector performance and noise assessment. The intrinsic vortex dynamics and intermediate state evolution, within the superconducting film volume, are fundamental features to clarify for pushing an experimental detector sensitivity to the sub-eV sensitivity threshold necessary to MARE. The proposed work focuses on two topics: the better understanding of the superconducting-to-normal phase transition of the sensor, absorber and overall microcalorimeter; low noise high-sensitive unconventional microcalorimeter readout electronics. In particular, the study of superconducting transition edge sensors and its phase transition induced by radiation, while in a current biased mode. The scientific programme of this proposal is part of the MARE scientific programme performed by the international collaboration.