Transmission of torque at the nanoscale

TL;DR

This paper demonstrates nanoscale torque transmission using a colloidal assembly with clutch-like behavior, revealing how thermal fluctuations influence efficiency and transmission modes, and optimizing conditions for maximum power output.

Contribution

It introduces a nanoscale torque transmission mechanism using colloidal particles, highlighting clutch-like behavior and the influence of thermal fluctuations on efficiency.

Findings

Torque transmission depends on solid-like or fluid-like states.

Transmission is affected by rotation rate and particle density.

Optimal conditions maximize power output.

Abstract

In macroscopic mechanical devices torque is transmitted through gearwheels and clutches. In the construction of devices at the nanoscale, torque and its transmission through soft materials will be a key component. However, this regime is dominated by thermal fluctuations leading to dissipation. Here we demonstrate the principle of torque transmission for a disc-like colloidal assembly exhibiting clutch-like behaviour, driven by $27$ particles in optical traps. These are translated on a circular path to form a rotating boundary that transmits torque to additional particles confined to the interior. We investigate this transmission and find that it is determined by solid-like or fluid-like behaviour of the device and a stick-slip mechanism reminiscent of macroscopic gearwheels slipping. The transmission behaviour is predominantly governed by the rotation rate of the boundary and the density of the confined system. We determine the efficiency of our device and thus optimise conditions to maximise power output.