Piezo actuator device and motor

A piezo actuator comprising:

• a piezo material having
• a top surface,
• a bottom surface, and
• a circumference surface,
• the piezo material having a polarity and the piezo material comprising one or more mounting holes in the piezo material, the one or more mounting holes being positioned substantially central in at least the top surface or the bottom surface of the piezo material,
• at least one contact point for contacting a load to be actuated, the at least one contact point being positioned on the circumference surface of the piezo material, and
• a set of electrodes being positioned on the top surface of the piezo material and at least one electrode being positioned at the bottom surface of the piezo material;
• wherein the electrodes are electrically connected and configured such that, taking into account the polarity of the piezo material, driving of the electrodes induces an in-plane bending mode and/or an in-plane expansion mode, wherein the in-plane bending mode is an oscillation mode wherein adjacent corners move in opposite sense and wherein the in-plane expansion mode is an oscillation mode wherein different corners of the top surface move in a same direction being synchronously outward or inward.