Optimization and characterization of a miniaturized piezoelectric inchworm actuator for large force/ stroke applications in implants

Abstract:
A miniaturized and flat piezoelectric inchworm linear motor was developed, characterized, and optimized for use in distraction osteogenesis in the jaw area. The necessary clamping on a high-precision guide rail is achieved by two clamps with an oval design, in which piezo stacks are arranged in the direction of movement. On one hand, this ensures a holding function without electrical power, on the other hand, clamping and releasing actions also lead to a clamping movements in the direction of movement, which have a major influence on the reliability and function of the motor, particularly due to the different clamping properties of the two locally separated clamps. By optimizing the clamp design, the clamping of the piezo stacks in the clamps, and through intelligent control, reliable movements in both directions and holding forces of up to 20 N could be achieved despite the very small size of the inchworm drive unit of 36x18x3 mm³, thus achieving characteristics that have not yet been demonstrated in the state of the art. Due to the monolithic and latch free design of the inchworm insert and the guide rail, the motor consists of only eight parts, which simplifies assembly and encapsulation when using the motor as a long-term implant.