Diamagnetic particle separation by shape in ferrofluids.

Separating particles, which can be either biological or synthetic, in a continuous label-free manner is essential to many applications. Magnetic separation has several advantages over other fielddriven particle separation techniques. It, however, has been limited primarily to situations where particles differ in size or magnetization. We demonstrate in this paper a continuous-flow separation of equal-volumed spherical and peanut-shaped diamagnetic particles in a dilute ferrofluid. This separation is attributed to the shape-dependent magnetophoretic motion, which is the combined result of the shape dependences of the magnetic force and viscous drag. We also develop a threedimensional numerical model to understand this shape-based diamagnetic particle separation and predict the effects of the determining factors. [ABSTRACT FROM AUTHOR]