Design of Multi-Degrees-of-Freedom Microrobots Driven by Homogeneous Quasi-Static Magnetic Fields

Wireless robots at the subcentimeter size are often actuated using externally generated magnetic fields. For most applications, these remote magnetic microrobots are located relatively far from the magnetic field generation sources. In this condition, all microrobots receive approximately the same driving magnetic field (which we term a homogeneous field). While some solutions have been presented to allow for the creation of simple onboard tools, the full potential of the homogeneous magnetic field for multi-degrees-of-freedom (DOF) actuation has not been exploited. Here we introduce a design framework to utilize the maximum number of independently controlled DOFs on a microrobot system. We make use of three classes of mechanisms which are commonly used in practice and allow for more complex microrobots with up to eight DOFs. To verify the functionality of our framework, we used it to design an optimized drug delivery robot equipped with a 3-DOF drug-releasing mechanism and a 4-DOF motion mechanism. Experiments are performed to actuate each one of the robot's seven DOFs individually, where the cross-talk error between these seven DOFs averaged 7% with a max error of 18.3%.