Three-dimensional maneuverable microrobots with single-beam actuation

Abstract

Light-driven microrobots offer great opportunities for non-contact manipulation at the nanoscale but are typically restricted to planar motion and require complex optical setups. Here, we report a microrobot capable of full five-degree-of-freedom (5-DoF) motion control using a single unfocused illumination with switchable wavelength and polarization. The design integrates a hybrid plasmonic nanomotor system leveraging wavelength and polarization multiplexing for independent actuation. Specifically, a central triangular antenna dimer operating at 650 nm provides directional scattering for in-plane translation, while asymmetrically slotted nanodisks positioned at the corners and driven at 1250 nm generate differential torques for out-of-plane pitch and roll. This dual-wavelength, single-beam strategy decouples translation and reorientation control, enabling precise, addressable manipulation without optical crosstalk. The presented framework establishes a compact and versatile platform for light-driven microrobots, advancing applications in targeted drug delivery and in situ biochemical sensing.