Effect of hydrodynamic inter-particle interaction on the orbital motion of dielectric nanoparticles driven by an optical vortex

Abstract

We experimentally and theoretically characterize dielectric nano- and microparticle orbital motion induced by an optical vortex of the Laguerre–Gaussian beam and investigate the role of hydrodynamic inter-particle interaction.

Electrical Sensing of Au Nanoparticles Manipulated by an Optical Vortex

“…The effect caused by the imperfection of optical vortices on the particle motions was also discussed in a previous study. 33 On the other hand, the optical manipulation errors did not cause a serious problem in the electrical measurements.…”

“…Details of the optical setup are also published elsewhere. 33 An electric voltage is applied across the double-slit structure using Ag/AgCl wire electrodes inserted into the inlet and outlet holes through the PDMS substrate. The other ends of the electrodes are connected to a voltage source (PMX18-5A, Kikusui Electronics Corp., Yokohama, Japan) or current amplifier (VersaSTAT 4, AMETEK Inc., Berwyn, PA, USA).…”

“…Using micro- and nanofluidic channels that guide electrically charged objects by the electrophoresis and/or electroosmotic flows (EOFs), the transport efficiency may be improved when the design of the devices is optimized. − We also previously proposed some methods for the measurement of resistive pulses, controlling the transport of target particles using optical manipulation techniques. , Such optical techniques have been used in various research fields − since the potential of optical tweezers was demonstrated by Ashkin and his co-workers. − Optical manipulation of biological cells, , biomacromolecules, and small colloid particles , was used to accurately determine the positions or to form ordered structures. In this study, we further apply an optical vortex − that induces an orbital motion of a gold nanoparticle (Au NP). An optical vortex, which has an orbital angular momentum (topological charge), drives a small object into a circular orbital motion due to the gradient and scattering forces. ,− Herein, a double-slit structure is fabricated in a nanochannel and the size is adjusted to the orbital radius.…”

L‐serine polymorphism controlled by optical trapping with high‐repetition‐rate femtosecond laser pulses

“…In this experiment, the fs laser pulses were focused near the three-phase point (see Figure 2), which serves as a stagnation point because of suppressed convection flow. [41,42] Another important reason for setting the focus at the three-phase point is that the scattering force also contributes to the increase in local concentration. In general, when the laser beam is tightly focused by an objective lens with a high NA, gradient force becomes much larger than the scattering one.…”

Reconfigurable label-free shape-sieving of submicron particles in paired chalcogenide waveguides

“…12 Nevertheless, less effort has been put into developing quick and efficient sieve schemes based on shape. The hydrodynamic effect is a potential strategy, 13 whereas it is only applicable for large micronsized particles (i.e., length > 5 μm, diameter > 1.7 μm). [14][15][16] Note that, submicron particles, including bacteria (diameter = 0.4-0.8 μm, length ≤ 2 μm), have comparable refractive indexes and scales, 17,18 however different shapes.…”