Analysis of flapping mechanism for acoustically actuated microrobotics

The field of microrobotics has vast applications including non-invasive surgery, targeted drug delivery, and telemetry. Many groups are developing or have developed magnetically based actuation methods for microrobotics. These magnetically based systems can potentially lead to undesirable effects on the human body. Acoustic control provides an interesting alternative to existing magnetic or electrostatic actuation in that acoustic signals include few harmful effects on the human subject. Furthermore, the use of acoustic signals allow for the possibility to leverage existing medical imaging technology. This paper describes an alternative method of actuation which utilizes double-jointed, flagella-like, flappers designed for whip-like, non-reciprocal motion. The flapper mechanism was investigated using COMSOL Multiphysics finite element software to determine eigenfrequencies. Flappers were then constructed from laser cut acrylic and styrene and joined with plastic cement. The flappers were excited to resonance and displayed behavior that was consistent with simulation. A 130 mm × 50 mm × 0.2 mm robot with the flapper tail was then constructed and tested in a tank containing water and an underwater speaker. The robot exhibited forward velocities as high as 2.5 mm/s as well as frequency selectivity, which could be exploited to achieve steering in the future by using multiple flappers with different resonance frequencies. This project lays the foundation for the development of an acoustically actuated microscale robot.