Linear Force Scaling in Kinesin-Driven Microtubule Swarms Revealed by Electromagnetic Tweezers.

Scalability refers to the ability of a system to enhance performance with increasing size. This ability is a defining feature of natural swarms such as ant and bee colonies. Extending this principle to artificial active matter has motivated the creation of molecular swarms composed of myosin-driven actin filaments and kinesin-driven microtubules (MTs). While these swarms exhibit cooperative transport behaviors that surpass the abilities of individual filaments, their collective force generation has remained unquantified. Here, we introduce a straightforward electromagnetic tweezer approach to directly measure the forces generated by MT swarms propelled by surface-bound kinesin motors. We find that force output changes with swarm size, demonstrating quantitative scalability characterized by a linear dependence of collective force on the inferred number of kinesin motors, linking collective organization to mechanical performance. These results characterize the scaling of collective force with swarm size in kinesin-driven MT swarms and highlight the link between collective organization and mechanical performance.