Cargo Size Limits and Forces of Cell-Driven Microtransport

Area of Science:

• Biophysics
• Microscale Engineering
• Cellular Mechanics

Background:

• Biohybrid microrobots leverage motile cells for unique properties like self-propulsion and stimulus response.
• Dictyostelium discoideum cells offer a model system for biohybrid locomotion due to their amoeboid movement.

Purpose of the Study:

• To investigate the relationship between cargo size and speed in cell-driven microrobots.
• To determine the scaling laws for viscous drag force on spherical cargo particles.
• To predict the maximal cargo size sustainable by Dictyostelium discoideum cell propulsion.

Main Methods:

• Experimental characterization of cell-cargo systems with varying spherical cargo radii.
• Development of a simplified geometrical model for cell-cargo interaction.
• Extrapolation of experimental findings to predict behavior at larger cargo sizes.

Main Results:

• Cargo speed and viscous drag force were found to scale with increasing cargo radius.
• A maximal cargo size was predicted, beyond which cell-driven movement is expected to cease.
• Cellular forces demonstrated mechanoresponsive adaptation, increasing significantly under external pulling forces.

Conclusions:

• The study establishes fundamental limits for cargo size in cell-powered microrobots.
• Cellular force adaptation is a key mechanism for navigating complex environments.
• Findings inform the design of advanced biohybrid systems for cargo transport and sensing.