an energy harvesting shock absorber includes first and second body portions , where the second body portion defines a fluid chamber . a piston located in the fluid chamber divides the fluid chamber into first and second regions . a rod mechanically couples the piston to the first body portion . a coil surrounds at least a portion of the fluid chamber . a ferromagnetic fluid is in the fluid chamber for moving to induce a change in magnetic flux in the coil , to lubricate an inner surface of the fluid chamber , and to damp relative motion between the first and second body portions .