A nanoscale robotic cleaner

TL;DR

Tiny light-powered nanorobots can move and manipulate bacteria using laser polarization, acting as microscopic robotic cleaners.

Contribution

Sub-micrometer nanorobots with plasmonic directional antennas enable efficient bacterial manipulation via laser polarization.

Findings

Nanorobots reach propulsion speeds up to 50 μm/s with motion direction locked perpendicular to the linear polarization axis.

Circularly polarized light pulses lift orientational degeneracy through spin–momentum transfer.

Nanorobots can capture, transport, reversibly assemble, and release bacteria using opto-thermophoretic forces.

Abstract

Photon-recoil–based actuation enables maneuvering of micro- and nanoscale objects without beam steering or tight focusing, mitigating system complexity and photodamage. Recent light-driven microdrones achieved full control in two dimensions using multiple laser fields; however, for many applications, sacrificing degrees of freedom allows substantial miniaturization and improved propulsion efficiency. Here, we demonstrate sub-micrometer nanorobots actuated by a plasmonic directional antenna that simultaneously provides propulsion force and orientation control. The nanorobots reach propulsion speeds up to 50 μm/s, with their motion direction intrinsically locked perpendicular to the linear polarization axis. Circularly polarized light pulses lift the resulting twofold orientational degeneracy through spin–momentum transfer. Using opto-thermophoretic forces, nanorobots efficiently capture, transport, reversibly assemble, and release bacteria. By sequencing linear and circular polarization states, they execute complex, high-precision trajectories to systematically sweep defined regions, functioning as light-driven robotic cleaners. This work expands the capabilities of nanorobots for biological manipulation and high-speed, localized sensing.

Submicron light-driven nanorobots powered by a plasmonic directional nanoantenna are controlled by laser polarization. They move rapidly along complex paths and capture, assemble, transport, and release bacteria, functioning as robotic cleaners.

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