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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.
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This content will become publicly available on May 22, 2026
Illuminating the Impact of Nonaqueous Solvents on Optical Trapping
The optical trapping of colloidal semiconductor nanomaterials would enable single-particle photophysics, sensing, and chemical measurements. Yet, the trapping of these materials has lagged behind other dielectric and metallic materials due to the prevalence of aqueous solvents in optical trapping experiments, which are not suitable for many semiconductors. Here, we trap particles in multiple solvents and study the impact of nonaqueous solvents on optical trapping dynamics. These experiments and calculations show that there exists an optimal refractive index of the media that maximizes trapping strength and for colloidal nanomaterials a universal relationship to enhance trap strength. We also find that viscosity has no impact on the trap strength and changes only the residence times of particles in unstable traps. Trap stiffness measurements also show that photothermal effects, which are enhanced in nonaqueous solvents, can lead to convection, which modifies trap stiffnesses. These results provide an understanding of how solvent selection impacts trapping dynamics and general design rules for experiments in nonaqueous solvents, opening the door for improved sensing, chemistry, and photophysics studies using colloidal micro- and nanomaterials.
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- Award ID(s):
- 2240479
- PAR ID:
- 10645849
- Publisher / Repository:
- ACS / Journal of Physical Chemistry C
- Date Published:
- Journal Name:
- The Journal of Physical Chemistry C
- Volume:
- 129
- Issue:
- 20
- ISSN:
- 1932-7447
- Page Range / eLocation ID:
- 9405 to 9412
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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