Modeling of a propulsion mechanism for swimming microrobots inspired by ciliate metachronal waves

The envisioned applications of microrobots in bodily fluids have raised the demand for effectively swimming microdevices. Microorganisms have become a source of inspiration because their mechanisms of propulsion are effective at low-Re. We investigated the theoretical performance of swimming microrobots implementing propulsion inspired by metachronal waves. These come from the spontaneous coordination of cilia and are responsible for the high swimming speeds of ciliates. We found that microrobots of typical length below the millimeter could self-propel at speeds of several bodylengths per second. The microrobots were assumed to have a continuous active surface exhibiting traveling-wave deformations that mimic metachronal waves. We developed an FE model for analyzing the performance of propulsion of such bio-inspired microrobots in water. In particular we evaluated how velocity is affected by various parameters, such as the shape and size of the microrobot, and the frequency, wavelength and amplitude of the surface deformations. We believe that the proposed mechanism is advantageous over other methods of propulsion because it does not need external thin and fragile appendages. The results of this analysis could thus guide us towards the design of effective self-propelling microrobots.