3D printed viscotactic microswimmers

Microorganisms exhibit autonomous locomotion through complex media and can react to changes in their environment. This ability of bacteria and living cells to adapt their motion in response to external stimuli is called taxis [1]. Leptospira bacteria, for example, swim towards regions of high viscosity [2]. While different kinds of taxis have been studied, the mechanism behind viscotaxis was not investigated until recently. Liebchen et al. found that swimmers with nonuniaxial body shapes swim up viscosity gradients due to the generation of asymmetric viscous torques acting on different parts of the swimmer. We are testing these theoretical predictions using artificial microswimmers created by 3D printing based on two-photon lithography that gives us access to virtually any shape [4]. We have started with the fabrication of trimers on the micrometre scale, the simplest form of a nonuniaxial body shape.

1) D. B. Dusenbery, Living at Micro Scale, Harvard University Press, 2009.
2) M. G. Petrino et al., J. Gen. Microbiol., 1978, 109, 113-117.
3) B. Liebchen et al., Phys. Rev. Lett., 2018, 120, 208002.
4) R. P. Doherty et al., Soft Matter, 2020, DOI:10.1039/D0SM01320J.