In this work the characterization of two sensors produced using the H35 and aH18 technologies by ams AG, the H35DEMO and the ATLASPIX1, is presented. The characterization focused on the charge-collection performance, the particle detection efficiency and the spatial and time resolution, measured before and after irradiation using protons and neutrons. The charge-collection performance has been studied using the transient current technique. The results have shown that the depletion depth increases significantly due to the acceptor removal effect of irradiation, which can compensate for the charge carriers loss caused by trapping. The particle detection efficiency and the space and time resolution have been studied in several testbeam campaigns. Results have shown an excellent efficiency, larger than 99%, which does not degrade after neutron irradiation. Proton irradiation, instead, produces a decrease in efficiency to 95% at a fluence of 1e15 neq/cm^2. These measurements have also allowed identifying a few shortcomings in the read-out circuitry, addressed in subsequent designs.