Magnetophoretic force and homogeneity optimization in multiplexed magnetic tweezers for microrheometry applications

Abstract

In order to generate homogeneous magnetophoretic forces, current magnetic tweezer devices operate placing electromagnetic inductors far enough from the sample. Consequently, high-power supplies are needed to reach sufficiently large forces. We demonstrate that both magnetophoretic force magnitude and homogeneity can be increased at will in this kind of devices by simply placing appropriate magnetic materials between the inductors and the sample. Choice of these material shape and location is made upon an extensive optimization process performed with finite element method simulations. Optimal configuration is shown to create large and homogeneous magnetophoretic forces over areas extensive enough to perform multiplexed microrheology tests with different values of force and pulse duration. A good correspondence is obtained between the experiment and the results from the simulations.