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arXiv · 2005.12703

Bio-inspired acousto-magnetic microswarm robots with upstream motility

Daniel Ahmed·David Hauri·Alexander Sukhov·Dubon Rodrigue·Maranta Gian·Jens Harting·Bradley Nelson
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Abstract

The ability to propel against flows, i.e., to perform positive rheotaxis, can provide exciting opportunities for applications in targeted therapeutics and non-invasive surgery. To date, no biocompatible technologies exist for navigating microparticles upstream when they are in a background fluid flow. Inspired by many naturally occurring microswimmers such as bacteria, spermatozoa, and plankton that utilize the non-slip boundary conditions of the wall to exhibit upstream propulsion, here, we report on the design and characterization of self-assembled microswarms that can execute upstream motility in a combination of external acoustic and magnetic fields. Both acoustic and magnetic fields are safe to humans, non-invasive, can penetrate deeply into the human body, and are well-developed in clinical settings. The combination of both fields can overcome the limitations encountered by single actuation methods. The design criteria of the acoustically-induced reaction force of the microswarms, which is needed to perform rolling-type motion, are discussed. We show quantitative agreement between experimental data and our model that captures the rolling behaviour. The upstream capability provides a design strategy for delivering small drug molecules to hard-to-reach sites and represents a fundamental step toward the realization of micro- and nanosystem-navigation against the blood flow.

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cond-mat.softphysics.bio-phphysics.flu-dyn

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Daniel Ahmed, David Hauri, Alexander Sukhov, Dubon Rodrigue, Maranta Gian, Jens Harting, Bradley Nelson. 2020-05-20. Bio-inspired acousto-magnetic microswarm robots with upstream motility. https://doi.org/10.1038/s42256-020-00275-x

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