Title:
Speedy nanorobots could someday clean up soil and water, deliver drugs
Author:
Kelsey Simpkins, University of Colorado at Boulder
Published:
Phys.org, 29 June 2021
From the article:
University of Colorado Boulder researchers have discovered that minuscule, self-propelled particles called "nanoswimmers" can escape from mazes as much as 20 times faster than other passive particles, paving the way for their use in everything from industrial clean-ups to medication delivery.
Also see
Title:
Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix
Authors:
Haichao Wu, Benjamin Greydanus & Daniel K Schwartz
Published:
Proceedings of the National Academy of Sciences (2021)
Abstract:
Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.