Confined Bubble‐Propelled Microswimmers in Capillaries: Wall Effect, Fuel Deprivation, and Exhaust Product Excess

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2020-07, Vol.16 (27), p.e2000413-n/a
• Main Authors: Khezri, Bahareh, Novotný, Filip, Moo, James Guo Sheng, Nasir, Muhammad Zafir Mohamad, Pumera, Martin
• Format: Article
• Language: English
• Subjects: Capillaries; Confined spaces; confinement; Depletion; Deprivation; Fuels; hydrodynamic interactions; Materials science; microfluidic channels; Micromotors; microswimmers; Nanotechnology
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202000413

Self‐propelled autonomous nano/microswimmers are at the forefront of materials science. These swimmers are expected to operate in highly confined environments, such as between the grains of soil or in the capillaries of the human organism. To date, little attention is paid to the problem that in such a confined environment the fuel powering catalytic nano/microswimmers can be exhausted quickly and the space can be polluted with the product of the catalytic reaction. In addition, the motion of the nano/microswimmers may be influenced by the confinement. These issues are addressed here, showing the influence of the size of the capillary and length of the micromotor on the motion and the influence of the depletion of the fuel and excess of the exhaust products. Theoretical modeling is provided as well to bring further insight into the observations. This article shows challenges that these systems face and stimulates research to overcome them. Confined space alters the swimming behaviors of the self‐propelled microswimmers due to hydrodynamic interactions between boundaries and swimmers, an effect similar to inertial focusing of passive particles in the microfluidic flow.