Initiating revolutions for optical manipulation: the origins and applications of rotational dynamics of trapped particles

Abstract

The fastest-spinning man-made object is a tiny dumbbell rotating at 5 GHz. The smallest wind-up motor is constructed from a DNA molecule. Picoliter volumes of fluids are remotely controlled and their viscosity precisely measured using microrheometers based on miniscule rotating particles. Theoretical predictions for extraordinarily weak forces related to the presence of dark matter, dark energy and vacuum-induced friction might be revealed, and the surprising properties of light have already been experimentally evidenced. All of these exciting landmarks have only been possible thanks to the torque exerted by light, which enables rotation of an optically trapped particle. Here, we review how light can impart torque on optically trapped particles, paying close attention to the design of the properties of both the particle and the light field. We detail how the maximum achievable rotation speed is limited by the environment, but can simultaneously be used to infer properties of the surrounding medium and of the light field itself. We also review the state-of-the-art applications of light-driven rotors, as well as proposals for the next generation of measurements, particularly at the classical-quantum interface, which can be performed using rotating optically trapped objects.

Giant Diffusion of Nanomechanical Rotors in a Tilted Washboard Potential

“…[17] for its determination). Note that the rotation frequency can exceed GHz, which allows us to study material stresses due to centrifugal forces [33,34], measure ultraweak torques [35,36], and examine quantum features of rotation [37,38].…”

Angular momentum transfered by the field of a moving point charge

“…For practical applications, an important property of radiation is the torque acting on the object due to electromagnetic field. For example, to use radiation as optical tweeze rs and optical traps [27,[31][32][33]. From this point of view, it is of interest to find the flux of the radial component of the angular momentum through an area of finite dimensions located perpendicular to the radius vector.…”

“…The first experiments on the capture of particles in traps and their rotation were carried out at the end of the last century [31,32] and are still being carried out [28][29][30]. A detailed description of these works is given in recent review [33].…”

Microfluidic Synthesis, Control, and Sensing of Magnetic Nanoparticles: A Review

“…Microfluidic chips provide great opportunities for manipulating microparticles as well as nanoparticles. There are multiple methods for microfluidic-based nanoparticle sorting, including the ones based on hydrodynamic [ 74 , 75 , 76 ], dielectrophoretic [ 77 , 78 ], optical [ 79 , 80 , 81 ], acoustic [ 82 , 83 ], and magnetic forces. Here, we focus on the methods based on magnetic forces specially designed for manipulating magnetic particles.…”