Magnetic Control of Nonmagnetic Living Organisms

Author: Ahmed Al Harraq1, Min Feng2, Hashir M Gauri1, Ram Devireddy3, Ankur Gupta4, Qing Sun2, Bhuvnesh Bharti1
1 Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
2 McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
3 Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States.
4 Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80303, United States.
Conference/Journal: ACS Appl Mater Interfaces
Date published: 2024 Mar 26
Other: Special Notes: doi: 10.1021/acsami.4c02325. , Word Count: 203

Living organisms inspire the design of microrobots, but their functionality is unmatched. Next-generation microrobots aim to leverage the sensing and communication abilities of organisms through magnetic hybridization, attaching magnetic particles to them for external control. However, the protocols used for magnetic hybridization are morphology specific and are not generalizable. We propose an alternative approach that leverages the principles of negative magnetostatics and magnetophoresis to control nonmagnetic organisms with external magnetic fields. To do this, we disperse model organisms in dispersions of Fe3O4 nanoparticles and expose them to either uniform or gradient magnetic fields. In uniform magnetic fields, living organisms align with the field due to external torque, while gradient magnetic fields generate a negative magnetophoretic force, pushing objects away from external magnets. The magnetic fields enable controlling the position and orientation of Caenorhabditis elegans larvae and flagellated bacteria through directional interactions and magnitude. This control is diminished in live spermatozoa and adult C. elegans due to stronger internal biological activity, i.e., force/torque. Our study presents a method for spatiotemporal organization of living organisms without requiring magnetic hybridization, opening the way for the development of controllable living microbiorobots.

Keywords: active matter; biohybrids; magnetic manipulation; magnetophoresis; magnetostatics; microrobotics.

PMID: 38531044 DOI: 10.1021/acsami.4c02325