Spatiotemporal patterning of extensile active stresses in microtubule-based active fluids

TL;DR

This paper introduces optically controlled kinesin motors that enable precise spatiotemporal regulation of active stresses in microtubule-based fluids, allowing dynamic control over chaotic flow behaviors.

Contribution

It presents a novel method for optically modulating active stresses in active fluids using engineered kinesin motors with clustering capabilities.

Findings

Optically enhanced kinesin clustering enables reversible switching of active stress states.

Spatio-temporal patterning controls bend-instability and critical length dependence.

One-time switching from contractile to extensile stresses is achieved.

Abstract

Active stresses, which are collectively generated by the motion of energy-consuming rod-like constituents, generate chaotic autonomous flows. Controlling active stresses in space and time is an essential prerequisite for controlling the intrinsically chaotic dynamics of extensile active fluids. We design single-headed kinesin molecular motors that exhibit optically enhanced clustering, and thus enable precise and repeatable spatial and temporal control of extensile active stresses. Such motors enable rapid, reversible switching between flowing and quiescent states. In turn, spatio-temporal patterning of the active stress controls the evolution of the ubiquitous bend-instability of extensile active fluids and determines its critical length dependence. Combining optically controlled clusters with conventional kinesin motors enables one-time switching from contractile to extensile active stresses. These results open a path towards real-time control of the autonomous flows generated by active fluids.