A wireless microrobot with 3 DOFs in pipe for medical applications

In this paper, to implement the locomotion of the microrobot in the organ of digestion or small area such as blood vessels, we designed a wireless microrobot with 3DOFs in pipe with characteristics of multi-functions, controllability, and stability. In addition, the microrobot has light weight and simple structure, simple control method, and good dynamic performance in the water. Firstly, we developed the novel type microrobot using a magnetic sheet to implement stable motion and lightweight structure, which could swim wirelessly by using outside magnetic field as the moving energy. This kind of microrobot has two motion mechanisms, which are spiral motion and fin motion. Based on these two motions, we proposed a hybrid motion with wireless control. Secondly, we proposed the three axes helmholtz coil system to enable multi DOFs locomotion to the microrobot and carried out some experiments to evaluate its characteristics. The experimental results indicated that this coil system could generate regular magnetic flux density within 0.15 meters between center-to-center distances in the pare coils. So, we confirmed that the microrobot could move under regular magnetic field by using this coil system. Thirdly, by applying the outside magnetic field, we evaluated its swimming speeds for rotating motion and driving motion in a pipe. The results indicated when the frequency changed from 0Hz to 10Hz, the fin motion was superior to the spiral motion; when the frequency was over 10Hz, the spiral motion was superior to the fin motion. This microrobot will play an important role in both industrial and medical applications.