Optical Fractionation Research In Periodic Conservative Optical Force Field

Light power is the force of light received by particles in the light field.It can be divided into two parts: gradient force and scattering force.The gradient force is a conservative force,mainly due to the uneven distribution of the intensity of the light field.Its effect on the microparticles is mainly to pull the microparticles to the maximum or minimum intensity in the light field,which can be used alone to trap particles.The scattering force(also called the optical radiation pressure)is a non-conservative force that usually pushes the particles to move along the direction of light propagation.Its main function is to transport the particles.Gradient and scattering forces are powerful tools for manipulating and trapping particles.Researchers have achieved a series of important results based on the different properties of gradient force and scattering power.The light is the most well-known example.This paper will use the relevant properties of the gradient force to manipulate the transport of the particles.We studied the motion characteristics of micro-nanoparticles in a pure gradient force field,a periodic conservative optical field.It is found that the trajectories of micronanoparticles in the optical field exhibit a peculiar step.Through a large number of numerical calculations,we also found that the trajectories and directions of motion of micro-nano particles of different sizes and speeds in the optical field may be very different.Therefore,we can use this to perform particle sorting.On the micro-nano scale,many disciplines are looking for ways to accurately and efficiently separate colloids,cells,and other biological particles.This separation method plays a key role in promoting biological and medical research.By numerical method,we simulate the trajectory of micro-nano particles,and obtain the motion law of a large number of particles passing through the periodic conservative optical force field.It provides reference and alternative program for the experimental work and practical application of screening particles and performing particle optical fractionation.