Sammendrag
Bimorphly actuated piezoelectric thin films offer an efficient low-power route for generating microelectromechanical motion compared to e.g. electrostatic or thermo-mechanical actuation principles [1]. This is since a large effective in-plane stress can be generated by applying relatively low voltages perpendicular to the plane [2]. The stress can then be transposed to a bending moment to generate mechanical motion. However, the piezoresponse of thin-film devices can be considerably perturbed by changing in-plane circumstances from for example residual stress or degradation from operation in realistic environments such as cracking, pinholing, or delamination and will strongly affect the response of piezoelectric microelectromechanical systems (piezoMEMS) [3], [4]. Due to the large variety of available piezoMEMS-devices, the response and dominating cause of failure can be as unique as the device itself, and it is therefore important to identify the nature of the degradation mechanism and its effect on the relevant device.