A shaker with a Terfenol-D rod actuator includes a mass coupled to both ends of the rod through a spring seat, a spring seat/adjuster and a spring washer. The actuator is mounted inside a cylindrical coil, which in turn is mounted inside a cylindrical permanent magnet, which in turn is mounted inside a cylindrical housing. An electrical drive system provides a predetermined excitation signal to the coil to cause the rod to vibrate under the influence of the magnetic field generated by the coil. One embodiment features a vibrating mass on one end of the rod. An implantable shaker includes a seal to leak-proof the shaker and a coating of Biomer™. The implantable shaker can be implanted in an animal to test tissue response to certain vibrations. According to another embodiment, the Terfenol-D rod actuator is held in place on one end with a pre-stress adjusting screw, which is threaded into the end of the housing and fixed in place with a jam nut. In all embodiments, a spring base is seated on one end of the rod actuator and forms an annular coaxial air gap between it and a spring seat, so that the air gap remains constant when the rod actuator vibrates and the spring base moves coaxially with respect to the spring seat.