Some embodiments relate to an energy conversion device comprising: a casing; a magnet disposed in the casing: an object in the casing attracted to the magnet and free to move relative to the magnet in at least two degrees of freedom; and at least one transducer element positioned to be affected by changes in a magnetic field of the magnet; wherein movement of the object relative to the magnet varies the magnetic field through the at least one transducer element, thereby generating electrical potential across a part of the at least one transducer element. In some embodiments, the transducer element may comprise a magnetostrictive piezoelectric (MP) element and the electrical potential may be generated across a piezoelectric part of the MP element. Alternatively, the transducer element may comprise an electromagnetic (EM) coil element.