Dynamic analysis of microparticle behavior in quad-beam optic-fiber optical tweezers

In recent year, optic-fiber optical tweezers were considered as a valuable manipulated tool, allowing for trapping and sorting numerous interest microparticles in biological and microfluidic application. Especially for dual optic-fiber array with misalignment, vortex optical field can be utilized to cause particle realizing periodic orbital rotation, contributing to measure unknown parameters such as torque, viscosity, and angular momentum. Yet, this optic-fiber array with several misalignments creating more vortex fields remains an interesting work for a large range of microparticle trapping and rotation. Therefore, motion profiles of particle exerting by four optic-fibers forming quad-beam were studied by changing offset distance in our numerical model. Compared to dual beam, the array of such four optic-fibers has much more controllable variables, reflecting the asymmetric radial distance relevant to particle. Herein, these motion characteristics relevant to microparticle have been simulated based on ray optics approximation. Finally, dynamic simulations imply that quad-beam can generate two or more vortexes inducing particle to move in orbital rotation, which have revealed different rotational radius, direction, and velocity. As a results, this optic-fiber array may be readily implemented in cellular trapping and manipulation, exploring biophysical properties of different types of cell.