Fig. 4. Characterization of the microscopic oscillations of nanoparticles in the loosely overdamped system.
(A) Potential energies of 30-, 40-, and 50-nm gold nanoparticles trapped in the loosely overdamped system. The potential wells have widths of 14, 16.8, and 25.6 μm for 30-, 40-, and 50-nm gold nanoparticles when the energy is 10kBT, respectively. Inset shows the potential energy of a 40-nm gold nanoparticle trapped in a single-beam optical tweezer, with an NA of 1.4 and laser power of 30 mW. The width for 10kBT is only 40 nm in this single-beam trapping. (B) Square root of MSD of gold nanoparticles in their trapped positions. The red circles indicate the situations when the individual systems approach 99% of the steady states. (C) Experimentally measured displacements of 100-nm polystyrene nanoparticles and 40-nm gold nanoparticles during oscillation. (D) Experimental observation of local microscopic oscillation of the 100-nm polystyrene nanoparticle in the microchannel. Scale bar, 10 μm.