Analysis and design of wireless magnetically guided microrobots in body fluids

The active guidance of magnetic particles inside biological organisms for drug delivery, cell separation, and protein manipulation has been actively pursued in biomedical research for many years. Recent advances in the integration of magnetic materials in MEMS are enabling the convergence of these two technologies towards the realization of wireless magnetically guided biomedical microrobots. This paper discusses some of the fundamental design issues for a biomedical microrobot that is actively steered in body fluids using magnetic fields. The effects of miniaturization on magnetic, fluid drag, and gravity/buoyancy forces and on control stability are analyzed. The advantages of using hard magnetic materials and the state of the art in the integration of hard magnetic materials into MEMS devices are discussed. The analysis indicates that untethered microrobots capable of being navigated under external control within biological organisms including the human body is a realistic goal.