Abstract

Nanoscale weak force sensing in aqueous solution is of great interest to researchers from broad areas, including physics and biology. Here we developed a video tracking-based optical tweezers calibration method that enables the detection of the trap stiffness for low refractive index nanoparticles. We found that under resonance conditions, doping lanthanide ions inside a nanocrystal would substantially increase its trap stiffness, achieving a maximum optical trap stiffness of 0.086 pN μm^–1 mW^–1 for 23.3 nm radius nanoparticles. We further use the dielectric resonance effect to modulate the scattering spectrum of single nanoparticles for multiplexed interferometric scattering microscopy.

© 2023 The Author(s)