Abstract: A micromechanical inertial sensor includes a pair of proof masses suspended between a pair of fixed structures by beams attached between the ends of the proof masses and the fixed structures, such that the proof masses extend lengthwise along a first axis direction and are able to vibrate back and forth along a second axis substantially orthogonal to the first axis. Each beam attached to the proof masses has increased compliance in the first axis direction, relative to a linear beam of equivalent cross section, such that the beams have reduced resistance to stretching in the first axis direction as the proof masses vibrate in the second axis direction. In one embodiment of the invention, each beam is bowed or curved. Alternatively, compliance of the beam is increased by providing strain relief at one or both ends of the beam, or by providing an extensible portion in each beam.