Design of Piezoelectric Actuators By Optimizing the Electrodes Topology

Piezoelectric materials based actuators are highly recognized for the development of microrobotic systems thanks to their high bandwidth, high resolution and high force density. However, one of their main drawback is the low relative stroke (0.1% of actuator's size) that limits the actuator motion range. Overcoming this limitation is challenging but would increase the achievable working space of microrobots. In this letter, topology optimization method is used to maximize the actuator stroke. Instead of optimizing only the material density, we also consider the optimization of the electrodes polarity. This approach allows to combine both material expansion and compression in order to increase the actuator output displacement. To demonstrate this approach, two actuators were designed starting from a full domain considered as a basic reference piezoelectric actuator. The first design considered only the density optimization while the second one took into account the optimization of the topology of electrodes. Both simulation and experiment showed a good agreement between the obtained designs and the fabricated prototypes. The result revealed that the optimized design with polarization has an improved factors of 2.8 and 2.02 compared to full plate and actuator without electrodes optimization, respectively.