a linear resonant actuator includes : an electromechanical polymer actuator ; a substrate having a first surface and a second surface , the emp actuator being mounted on the first surface of the substrate ; clamping structure provided on two sides of the substrate so as to allow the substrate to vibrate freely between the two sides of the substrate , in response to an electrical stimulation of the emp actuator ; and an inertial mass element having a contact surface for attaching to the substrate at the second surface of the substrate . the inertial mass element may include contact structures provided to attach to the substrate along thin parallel lines . in one embodiment , the inertial mass element may have a “ t ” shape , or any suitable shape for stability .