This disclosure corresponds to methods and devices for tissue stimulation with electromagnetic fields by frequency scan. Said frequency scan referring to the variation of the electromagnetic field applied to a tissue via increments in frequency deltas which adapts to a tissue impedance response feedback. In addition, some methods of this disclosure allows determining stimulation frequency bands in order to focus stimuli in said bands until the tissue impedance response returns to a tolerance level or exceeds a maximum stimulation time. Devices for stimulating a tissue with electromagnetic fields comprising a computing unit; an external power source connected to the computing unit; a decoupling circuit connected to the external power source and to the computing unit; an arrangement of electromagnetic transducers connected to the computing unit and to the decoupling circuit; the computing unit executes disclosed methods to generate activation signals that receive the arrangement of the electromagnetic transducers.