Propulsion of a Molecular Machine by Asymmetric Distribution of Reaction Products

A simple model for the reaction-driven propulsion of a small device is proposed as a model for (part of) a molecular machine in aqueous media. The motion of the device is driven by an asymmetric distribution of reaction products. The propulsive velocity of the device is calculated as well as the scale of the velocity fluctuations. The effects of hydrodynamic flow as well as a number of different scenarios for the kinetics of the reaction are addressed.

Figure 1

The spherical particle with a reaction site.

Figure 2

Transient response of the velocity of propulsion after the reaction has been switched on.

Figure 3

Time evolution of the propulsive velocity for the case of periodic particle release, corresponding to $R/\sqrt{D{\tau }_{\mathrm{f}}}=1$.