This work presents a systematic procedure to design piezoelectrically actuated microgrippers. Topology optimization combined with optimal design of electrodes is used to maximize the displacement at the output port of the gripper. The fabrication at the microscale leads us to overcome an important issue: the difficulty of placing a piezoelectric film on both top and bottom of the host layer. Due to the non-symmetric lamination of the structure, an out-of-plane bending spoils the behaviour of the gripper. Suppression of this out-of-plane deformation is the main novelty introduced. In addition, a robust formulation approach is used in order to control the length scale in the whole domain and to reduce sensitivity of the designs to small manufacturing errors.
In this work, we present a systematic procedure to design piezoelectric transducers by simultaneously optimizing the host structure and the electrode layout. The technique allows maximizing any electromechanical coupling of output efficiency of the transducer. Either the output current collected at the electrodes when a mechanical force is applied (sensors), or the in-plane displacement when a given voltage is applied to the electrodes (actuators) can be optimized. We introduce a new idea to avoid the typical problem in topology optimization of the appearance of gray areas, getting finally 0-1 designs, some of which have been manufactured. Also, mathematical demonstration of reciprocity of the piezoelectric effect is shown. Many MEMS-based actuators like microgrippers, surface probes, or micro-optical devices can be optimized following this procedure. A similar approach has been demonstrated previously in modal sensors/actuators, although restricted to the design of the electrode layout for a given structure. The novel method shown here allows the simultaneous optimization of both shapes, for electrode and structure in the static case.