Magnetic Actuation for Full Dexterity Microrobotic Control Using Rotating Permanent Magnets

Recent work in magnetically actuated microscale robots for biomedical or microfluidic applications has resulted in magnetic actuation systems that can remotely command precise five-degree-of-freedom control of magnetic devices. This paper presents a new type of actuation system, which uses an array of rotating permanent magnets to generate the same level of control over untethered microscale devices with the potential for increased field and gradient strength and minimal heat generation. In contrast with previous permanent-magnet actuation systems, the system proposed here does not require any hazardous translational motion of the control magnets, resulting in a simple, safe, and inexpensive system. The proof-of-concept prototype system presented, with eight permanent magnets, can create fields and field gradients in any direction with variable magnitudes between zero and 30 mT and 0.83 Tm
^-1
, respectively. The effectiveness of the system is shown through characterization and feedback control of a 250-μm micromagnet in a 3-D path-following task with average accuracy of 25 μm. An optimization framework is presented for designing system configurations for targeted applications.