Position control of magnetic beads by means of electromagnetic fields with respect to apodal locomotion systems

Abstract

Motivated by the technical progress, electromagnetic action principles are more and more used in micro systems. It is well known that the discrete positioning of magnetic beads like ferrofluid droplets can be realised using an array of electromagnets whereat the position of the beads depends on the arrangement of the electromagnets. This paper refers to the analogous positioning of magnetic beads independent from the arrangement of the electromagnets. Therefore a control strategy was designed to position magnetic beads like ferrofluid droplets, ferrogels or ferroelastomers. The derived control law allows the definition of dynamic properties like time and damping constant. To achieve these properties, the controller is adjusted based on a model of the plant. This model regards the dynamical movement of the mentioned materials in electromagnetic fields and is characterised by simplified, nonlinear, ordinary differential equations. The theoretical results are verified by means of a basic assembly allowing the positioning of spherical ferroelastomers on macro scale. The measurements illustrate that the theoretically derived position controller meets the requirements of a predefined time and damping constant.