Metallic Microswimmers Driven up the Wall by Gravity

Quentin Brosseau; Florencio Balboa Usabiaga; Enkeleida Lushi; Yang Wu; Leif Ristroph; Michael D. Ward; Michael J. Shelley; Jun Zhang

arXiv · 2008.05273

Metallic Microswimmers Driven up the Wall by Gravity

Quentin Brosseau·Florencio Balboa Usabiaga·Enkeleida Lushi·Yang Wu·Leif Ristroph·Michael D. Ward·Michael J. Shelley·Jun Zhang

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Abstract

As a natural and functional behavior, various microorganisms exhibit gravitaxis by orienting and swimming upwards against gravity. Swimming autophoretic nanomotors described herein, comprising bimetallic nanorods, preferentially orient upwards and swim up along a wall, when tail-heavy (i.e. when the density of one of the metals is larger than the other). Through experiment and theory, two mechanisms were identified that contribute to this gravitactic behavior. First, a buoyancy or gravitational torque acts on these rods to align them upwards. Second, hydrodynamic interactions of the rod with the inclined wall induce a fore-aft drag asymmetry on the rods that reinforces their orientation bias and promotes their upward motion.

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Quentin Brosseau, Florencio Balboa Usabiaga, Enkeleida Lushi, Yang Wu, Leif Ristroph, Michael D. Ward, Michael J. Shelley, Jun Zhang. 2020-08-12. Metallic Microswimmers Driven up the Wall by Gravity. https://arxiv.org/abs/2008.05273

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