Gold Nanorod Rotary Motors Driven by Resonant Light Scattering

Abstract

Efficient and robust artificial nanomotors could provide a variety of exciting possibilities for applications in physics, biology and chemistry, including nanoelectromechanical systems, biochemical sensing, and drug delivery. However, the application of current man-made nanomotors is limited by their sophisticated fabrication techniques, low mechanical output power and severe environmental requirements, making their performance far below that of natural biomotors. Here we show that single-crystal gold nanorods can be rotated extremely fast in aqueous solutions through optical torques dominated by plasmonic resonant scattering of circularly polarized laser light with power as low as a few mW. The nanorods are trapped in 2D against a glass surface, and their rotational dynamics is highly dependent on their surface plasmon resonance properties. They can be kept continuously rotating for hours with limited photothermal side effects and they can be applied for detection of molecular binding with high sensitivity. Because of their biocompatibility, mechanical and thermal stability, and record rotation speeds reaching up to 42 kHz (2.5 million revolutions per minute), these rotary nanomotors could advance technologies to meet a wide range of future nanomechanical and biomedical needs in fields such as nanorobotics, nanosurgery, DNA manipulation and nano/microfluidic flow control.

Man-made rotary nanomotors: a review of recent developments

“…Note that more works on the rotation of metallic nanowire/nanorod were demonstrated recently, based on the transfer of orbital angular momentum of light [Figure 6(C)]. 121,124–126 …”

Opto-thermoelectric nanotweezers

“…Although the use of optical tweezers succeeded in trapping Au and Ag nanoparticles with different sizes and shapes 2-8 , it typically encounter technical obstacles. First of all, upon excitation of localized surface plasmons (LSPs) at metal nanoparticles by the trapping laser beam, enhanced light absorption and scattering result in optical heating of the particles and strong optical radiation forces, thereby significantly reducing the trapping stability 1,9,10 . As a result, optical trapping is limited to near-infrared lasers with wavelengths far away from the LSP resonance of the metal nanoparticles 3,4,9 .…”

Metasurfaces and Colloidal Suspensions Composed of 3D Chiral Si Nanoresonators

“…The Si nanocrescents have a complicated shape and their diffusion and friction coefficients in water are nontrivial. [35,36] All in all, these results open many new opportunities and perspectives for investigations and applications of high-index resonators in nanophotonics. This value is four times larger than what was found in the only previous report on optical trapping of high-index nanostructures, which considered elongated Si particles of varying aspect ratio.…”