https://doi.org/10.1140/epje/s10189-021-00050-9
Regular Article - Living Systems
Micromotor-mediated sperm constrictions for improved swimming performance
1
Institute for Integrative Nanosciences, Leibniz IFW Dresden e.V., Helmholtzstraße 20, 01069, Dresden, Germany
2
Center for Advancing Electronics Dresden, TU Dresden, 01069, Dresden, Germany
3
Cluster of Excellence ‘Physics of Life’, TU Dresden, 01307, Dresden, Germany
4
School of Science, TU Dresden, 01062, Dresden, Germany
5
Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), TU Chemnitz, Rosenbergstraße 6, 09126, Chemnitz, Germany
c
benjamin.friedrich@gmail.com
e
m.medina.sanchez@ifw-dresden.de
Received:
3
October
2020
Accepted:
3
March
2021
Published online:
11
May
2021
Sperm-driven micromotors, consisting of a single sperm cell captured in a microcap, utilize the strong propulsion generated by the flagellar beat of motile spermatozoa for locomotion. It enables the movement of such micromotors in biological media, while being steered remotely by means of an external magnetic field. The substantial decrease in swimming speed, caused by the additional hydrodynamic load of the microcap, limits the applicability of sperm-based micromotors. Therefore, to improve the performance of such micromotors, we first investigate the effects of additional cargo on the flagellar beat of spermatozoa. We designed two different kinds of microcaps, which each result in different load responses of the flagellar beat. As an additional design feature, we constrain rotational degrees of freedom of the cell’s motion by modifying the inner cavity of the cap. Particularly, cell rolling is substantially reduced by tightly locking the sperm head inside the microcap. Likewise, cell yawing is decreased by aligning the micromotors under an external static magnetic field. The observed differences in swimming speed of different micromotors are not so much a direct consequence of hydrodynamic effects, but rather stem from changes in flagellar bending waves, hence are an indirect effect. Our work serves as proof-of-principle that the optimal design of microcaps is key for the development of efficient sperm-driven micromotors.
© The Author(s) 2021
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