A piezoelectric bimorph cantilever beam system for harvesting electrical energy from vibrations, the system comprising: a shim including a first main surface, a second main surface opposite the first main surface, a proximal end connected to an anchor, and a distal end opposite the proximal end; a first piezoelectric layer made of piezoelectric material and laminated on the first main surface of the shim; a second piezoelectric layer made of piezoelectric material and laminated on the second main surface of the shim; and a first beam stiffener made of a polymer, a composite resin, a metal, an organic material, or a composite of a metal and an organic material, and provided over the first main surface of the shim adjacent to the anchor, the first beam stiffener at least partially covering the first piezoelectric layer, wherein the first beam stiffener: (a) has a variable thickness decreasing from the anchor towards the distal end of the shim and a substantially linear exterior surface decreasing from the anchor towards the distal end of the shim, or (b) has a variable thickness decreasing from the anchor towards the distal end of the shim and a curved exterior surface decreasing from the anchor towards the distal end of the shim, or (c) has a variable thickness decreasing from the anchor towards the distal end of the shim and comprises multiple layers (371a-378a) stacked on the piezoelectric layer with each of the multiple layers decreasing in length extending away from the shim, or (d) defines a plurality of holes (491-495 and 591-598) varying in size based on its location along the shim. a shim including a first main surface, a second main surface opposite the first main surface, a proximal end connected to an anchor, and a distal end opposite the proximal end; a first piezoelectric layer made of piezoelectric material and laminated on the first main surface of the shim; a second piezoelectric layer made of piezoelectric material and laminated on the second main surface of the shim; and a first beam stiffener made of a polymer, a composite resin, a metal, an organic material, or a composite of a metal and an organic material, and provided over the first main surface of the shim adjacent to the anchor, the first beam stiffener at least partially covering the first piezoelectric layer, wherein the first beam stiffener: (a) has a variable thickness decreasing from the anchor towards the distal end of the shim and a substantially linear exterior surface decreasing from the anchor towards the distal end of the shim, or (b) has a variable thickness decreasing from the anchor towards the distal end of the shim and a curved exterior surface decreasing from the anchor towards the distal end of the shim, or (c) has a variable thickness decreasing from the anchor towards the distal end of the shim and comprises multiple layers (371a-378a) stacked on the piezoelectric layer with each of the multiple layers decreasing in length extending away from the shim, or (d) defines a plurality of holes (491-495 and 591-598) varying in size based on its location along the shim. (a) has a variable thickness decreasing from the anchor towards the distal end of the shim and a substantially linear exterior surface decreasing from the anchor towards the distal end of the shim, or (b) has a variable thickness decreasing from the anchor towards the distal end of the shim and a curved exterior surface decreasing from the anchor towards the distal end of the shim, or (c) has a variable thickness decreasing from the anchor towards the distal end of the shim and comprises multiple layers (371a-378a) stacked on the piezoelectric layer with each of the multiple layers decreasing in length extending away from the shim, or (d) defines a plurality of holes (491-495 and 591-598) varying in size based on its location along the shim.