Magnetic Control of Nonmagnetic Living Organisms

Area of Science:

• Biophysics
• Microfluidics
• Robotics

Background:

• Living organisms offer unique sensing and communication capabilities for microrobot design.
• Current magnetic hybridization methods for microrobot control are organism-specific and lack generalizability.
• External control of nonmagnetic biological entities remains a significant challenge.

Purpose of the Study:

• To propose and validate a novel, generalizable method for controlling nonmagnetic organisms using external magnetic fields.
• To investigate the principles of negative magnetostatics and magnetophoresis for organism manipulation.
• To enable spatiotemporal organization of living microorganisms without invasive procedures.

Main Methods:

• Dispersing model organisms (C. elegans larvae, flagellated bacteria, spermatozoa, adult C. elegans) in Fe3O4 nanoparticle suspensions.
• Applying uniform and gradient magnetic fields to manipulate the organism-nanoparticle mixtures.
• Analyzing organism response, including alignment and movement, under varying magnetic field conditions.

Main Results:

• Uniform magnetic fields induced alignment of organisms via external torque.
• Gradient magnetic fields generated negative magnetophoretic forces, repelling organisms from magnets.
• Successful control of position and orientation was demonstrated for C. elegans larvae and flagellated bacteria.
• Control efficacy was reduced in live spermatozoa and adult C. elegans due to inherent biological forces.

Conclusions:

• A non-invasive method for controlling nonmagnetic organisms using magnetic fields and nanoparticles has been established.
• This approach overcomes the limitations of morphology-specific magnetic hybridization techniques.
• The findings pave the way for developing controllable living microbiorobots by enabling precise spatiotemporal organization.