Research And Implementation Of Micro-particle Rotation Driven By Swirl

Micromanipulation of micro particles is a representative technology of high-precision engineerings in the current world. And particle rotation is an essential and important part of micromanipulation, which has found wide-spread applications in chemical analysis, micro driving and especially biological engineering.This paper proposed a new kind of non-contact particle rotation method driven by swirl. Swirl is generated by two ejecting microtubes which are parallel placed, and the micro particle in swirl will rotate by the action of fluid viscous force. By adjusting the strength and direction of swirl, the rotation speed and direction of particle will change too. Matching the parameters of flow field, particles of different sizes and shapes can also be driven.First, this paper studied the formation and influence factors of swirl, introduced the particle rotation method driven by swirl, analyzed the forces and motion characteristics of particle in swirl, then discussed the influence factors of particle rotation performance.Aiming at the micro level particles, this paper built the dynamic model of particle rotation on the basis of the theoretical analysis, simulated the dynamic process of swirl and particle rotation, and explored the impact of swirl and particle parameters on rotation performance detailedly.Finally, a particle rotation experiment platform was set up and massive experiments were conducted. The feasibility of swirl method and reliability of numerical calculation were verified through comparing the simulation and experimental results.The research results indicate that swirl can be formed through two parallel placed ejecting microtubes, and particles can rotate steady in swirl. When a particle is not in the centre of flow field, the particle will move around the centre while rotating, and the distance from particle to swirl centre changes periodically. Furthermore, the particle will rotate steady in swirl even when the particle size, shape or location in swirl changes. According to various applications, different particle motions can be controlled by adjusting swirl. Particle trajectories are relative to particle size, shape and location in swirl. In order to capture and adjust the particle orientation easier, we should reduce the eccentricity of particle to minimize the particle motion around swirl centre. This paper takes micro-level particles as research object to carry out theoretical analysis and experiments, and the swirl method is still suitable for particles of different sizes by adjusting swirl parameters.