Towards active microfluidics: Interface turbulence in thin liquid films with floating molecular machines

TL;DR

This paper investigates how active protein machines in thin liquid films induce interface turbulence through mechanical motions, leading to instability and complex wave patterns, with implications for active microfluidic systems.

Contribution

It introduces a model of active protein machines causing interface instability and turbulence in thin films, highlighting the transition from flat to turbulent regimes.

Findings

Threshold energy supply causes interface instability.

Turbulent regime features traveling waves and machine clusters.

Numerical simulations support the theoretical model.

Abstract

Thin liquid films with floating active protein machines are considered. Cyclic mechanical motions within the machines, representing microscopic swimmers, lead to molecular propulsion forces applied to the air-liquid interface. We show that, when the rate of energy supply to the machines exceeds a threshold, the flat interface becomes linearly unstable. As the result of this instability, the regime of interface turbulence, characterized by irregular traveling waves and propagating machine clusters, is established. Numerical investigations of this nonlinear regime are performed. Conditions for the experimental observation of the instability are discussed.