Realization of a Soft Microrobot with Multiple Flexible Flagella

This work presents an approach to realize soft microrobots with multiple flexible flagella using beaded-fibers driven via a periodic magnetic field. Paramagnetic iron oxide particles are embedded into the polymer matrix of electrospun beaded-fibers and form magnetism upon applying an external magnetic field. We demonstrate that the induced magnetization by an external magnetic field enables self-assembly of multiple adjacent beaded-fibers to form a microrobot with multiple flexible flagella. Frequency response of the assembled microrobot and the individual beaded-fibers is characterized experimentally, and shows that the propulsive force imparted to the fluid by the multiple flexible flagella increases the actuation frequency range of the microrobot and enhances its swimming speed. At relatively high actuation frequency (20 Hz), the average speed of the individual beaded-fiber is 0.11 body-length-per-second, whereas the microrobot with multiple flagella swims at an average speed of 0.30 body-length-per-second. We also observe a slight difference in the swimming speed between the microrobot with multiple flexible flagella and its constituent beaded-fibers at relatively low actuation frequencies.