The present invention discloses an energy harvesting device that converts small magnitude and low frequency vibrations into electrical energy. The device can include a base, a low frequency element, and a piezoelectric element. The low frequency element can be movably attached to the base and the piezoelectric element can also be attached to the base and be spaced apart from the low frequency element with a vacant space therebetween. Upon vibration of the low frequency element resulting from environmental vibrations, the low frequency element can impact the piezoelectric element and cause elastic deformation thereto.