Patent ID: 8890553

Claim:
A method of detecting one or more cracks in a piezoelectric element of a micro actuator, the piezoelectric element interposed between a pair of electrodes formed on respective first and second surfaces of the piezoelectric element and the piezoelectric element deforming according to a voltage applied thereto through the pair of electrodes, comprising: detecting if there are cracks in the piezoelectric element before the micro actuator is installed into a device needing the micro actuator and initiates operation in the device, said detecting comprising: applying a voltage at a resonance frequency of the piezoelectric element to the piezoelectric element through the pair of electrodes; measuring a dielectric tangent between the pair of electrodes when said voltage at the resonance frequency is applied to the piezoelectric element; and determining that cracks in the piezoelectric element are present when a peak at said resonance frequency of the measured dielectric tangent between the pair of electrodes is less than a threshold.