An energy harvesting system comprising a frame, at least one permanent magnet having a North/South direction, and at least one winding (107, 108) wound according to a winding direction around a core (103a-103b) comprising a high magnetic permeability material, said permanent magnet being elastically mounted on the frame to be able to oscillate relatively to the winding (107,108), characterized-in-that: - at least two spreaders are stacked in a stack direction perpendicular to a plane comprising the North/South direction of the permanent magnet, and arranged at each pole of the permanent magnet, said spreaders being arranged in order to guide and concentrate a magnetic flux in direction of a magnetic circuit and being made of material having high magnetic permeability, separated by a magnetic and electric insulator made of non-conductive and non-magnetic material; - the spreaders and the permanent magnet being embedded in a polymer block holder elastically mounted on the frame by a spring and said block holder oscillating in direction; - and said magnetic circuit being fixed to the frame by a support, and surrounding the permanent magnet thus facing both, the North and the South, poles of the permanent magnet, and said magnetic circuit further comprising magnetic plates (104,105) alternatively stacked in stack direction with plates made of non-conductive and non-magnetic material defining a distance of step (e) between said magnetic plates (104,105) which is smaller than the total deflection (Δz); wherein the magnetic plates (104,105) being positioned along the plane, comprise a ringshaped part (104a,105a) and two cantilever arms (104b, 104c, 105b, 105c) extending along opposite internal directions of the ring shape part (104a, 105a) and extending symmetrically relative to the ring shape center; said cantilever arms (104b, 104c, 105b, 105c) being directly facing the spreaders attached to the poles of the permanent magnet, and said ring shape part (104a, 105a) surrounding the cantilever arms (104b, 104c, 105b, 105c) and the magnet; - the winding (107,108) being arranged around one part (103a, 103b) of the magnetic circuit at the same side as the North and South poles of the permanent magnet, part of the magnetic circuit being arranged between the winding bearing part and the permanent magnet, and part being arranged between the winding bearing part and the permanent magnet; said winding bearing part (103a, 103b) corresponding respectively to the ring shape part (104a, 105a) of the magnetic plates (104,105) and said part and corresponding respectively to the cantilever arms (104b, 105b, 104c, 105c) of the magnetic plates (104, 105). - at least two spreaders are stacked in a stack direction perpendicular to a plane comprising the North/South direction of the permanent magnet, and arranged at each pole of the permanent magnet, said spreaders being arranged in order to guide and concentrate a magnetic flux in direction of a magnetic circuit and being made of material having high magnetic permeability, separated by a magnetic and electric insulator made of non-conductive and non-magnetic material; - the spreaders and the permanent magnet being embedded in a polymer block holder elastically mounted on the frame by a spring and said block holder oscillating in direction; - and said magnetic circuit being fixed to the frame by a support, and surrounding the permanent magnet thus facing both, the North and the South, poles of the permanent magnet, and said magnetic circuit further comprising magnetic plates (104,105) alternatively stacked in stack direction with plates made of non-conductive and non-magnetic material defining a distance of step (e) between said magnetic plates (104,105) which is smaller than the total deflection (Δz); wherein the magnetic plates (104,105) being positioned along the plane, comprise a ringshaped part (104a,105a) and two cantilever arms (104b, 104c, 105b, 105c) extending along opposite internal directions of the ring shape part (104a, 105a) and extending symmetrically relative to the ring shape center; said cantilever arms (104b, 104c, 105b, 105c) being directly facing the spreaders attached to the poles of the permanent magnet, and said ring shape part (104a, 105a) surrounding the cantilever arms (104b, 104c, 105b, 105c) and the magnet; - the winding (107,108) being arranged around one part (103a, 103b) of the magnetic circuit at the same side as the North and South poles of the permanent magnet, part of the magnetic circuit being arranged between the winding bearing part and the permanent magnet, and part being arranged between the winding bearing part and the permanent magnet; said winding bearing part (103a, 103b) corresponding respectively to the ring shape part (104a, 105a) of the magnetic plates (104,105) and said part and corresponding respectively to the cantilever arms (104b, 105b, 104c, 105c) of the magnetic plates (104, 105).