In the piezoelectric type, the sensor is a tuning fork -shaped structure with four piezoelectric elements, two on top and two below. When the slip angle is zero (no slip), the upper elements produce no voltage as no Coriolis force acts on them. But when cornering, the rotational movement causes the upper part of the tuning fork to leave the oscillatory plane, creating an alternating voltage (and thus an alternating current) proportional to the yaw rate and oscillatory speed. The output signal's sign depends on the direction of rotation.