Separation and trapping of magnetic particles by insertion of ferromagnetic wires inside a microchip: Proposing a novel geometry in magnetophoresis

In this study, by placing two ferromagnetic wires with different diameters inside the microchannel, a non-uniform magnetic field is generated. The magnetic force of this non-uniform field, separates different magnetic particles from each other and collects them in different parts of the channel. Using this system, we are able to collect and separate different particles from each other with an efficiency of 97%. This phenomenon depends on parameters such as wire diameter and its magnetic sensitivity, external magnetic field intensity, particle magnetic sensitivity, particle size and magnetic sensitivity of the carrier fluid. Here, these parameters are examined individually for magnetic particles (M-280 and M-450) and the optimum parameters are specified. Then, by comparing various cases, a system, for simultaneous separation and trapping is proposed. In addition, one of the magnetophoresis problems, which is interaction forces between magnetic particles investigated for the proposed system. The effects of effective parameters such as the distance between the wires and the fluid velocity are optimized to obtain maximum efficiency. Particle M-280 and M-450 are collected by wires with diameter of 100 [mu m] and 50 [mu m] respectively. The optimum distance between two wires is 800 [mu m], so their magnetic field distribution have positive effect on each other. Also, to maximize the system efficiency the fluid velocity is set to 11 [mm/s]. By selecting these parameters as obtained values, the system efficiency is optimized. By changing wire diameter or magnetic field intensity, the proposed microchip can be used for separation and trapping of different particles.