Optimization of the size of a magnetic microrobot for high throughput handling of micro-objects

One of the greatest challenges in microrobotic is to handle individually a large number of objects in a short time, for applications such as cell sorting and assembly of microcomponents. This ability to handle a large number of microobjects is directly related to the size of the microrobot. This paper proposes a theoretical study of the size of a magnetic microrobot maximizing its capacity of displacement. It demonstrates that there is an optimal size can be obtained, due to a trade-off between the inertial and the viscous effects. Analytical expressions of the optimal size and the related frequency of motion are derived from a simplified model to highlight the influence of the geometrical and the physical parameters of the magnetic manipulation system such as the viscosity of the liquid and the size of the workspace. A numerical simulation validates the analytical analysis and demonstrates a high displacement capacity of the microrobot (around 100 back and forth motions per second for a robot of around 20 μm).