Abstract
Constructing colloidal particles into functional nanostructures, materials, and devices is a promising yet challenging direction. Many optical techniques have been developed to trap, manipulate, assemble, and print colloidal particles from aqueous solutions into desired configurations on solid substrates. However, these techniques operated in liquid environments generally suffer from pattern collapses, Brownian motion, and challenges that come with reconfigurable assembly. Here, we develop an all-optical technique, termed optothermally-gated photon nudging (OPN), for the versatile manipulation and dynamic patterning of a variety of colloidal particles on a solid substrate at nanoscale accuracy. OPN takes advantage of a thin surfactant layer to optothermally modulate the particle-substrate interaction, which enables the manipulation of colloidal particles on solid substrates with optical scattering force. Along with in situ optical spectroscopy, our non-invasive and contactless nanomanipulation technique will find various applications in nanofabrication, nanophotonics, nanoelectronics, and colloidal sciences.
Highlights
Constructing colloidal particles into functional nanostructures, materials, and devices is a promising yet challenging direction
The deposited CTAC acts as an optothermal gate to modulate the particle-substrate interface and allows for the manipulation of particles, which is pivotal for optothermally-gated photon nudging (OPN)
Apart from AuNPs, we demonstrated the nanomanipulation of other materials using OPN, such as silver nanoparticles (AgNPs) and silicon nanoparticles (SiNPs)
Summary
Constructing colloidal particles into functional nanostructures, materials, and devices is a promising yet challenging direction. The state-of-the-art chemical synthesis techniques permit the production of colloidal particles with precisely tunable sizes and shapes, tailorable compositions and unique properties[1,2,3,4,5] To build these colloidal particles into functional devices, the particles need to be assembled into the desired nanostructures and transported from an aqueous solution onto a solid substrate. CTAC surrounding the particle undergoes a localised order-disorder transition and turns into a quasi-liquid phase (Fig. 1c), where the nonpolar layers are melted while the ionic layers remain practically intact[29,30] This disordered structure significantly eliminates the van der Waals friction between the particle and CTAC layer, opening the optothermal gate for free particle motion. Opto-thermoelectric nanotweezers exploit CTAC that is dissolved into a colloidal solution to generate an optothermoelectric field to trap charged nanoparticles
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