Magnetically steerable manipulator with variable stiffness using graphene polylactic acid for minimally invasive surgery

For manipulators used in minimally invasive surgery (MIS), variable stiffness and miniaturization are very important characteristics. However, previously proposed mechanisms are difficult to miniaturize due to large and complex structures; thus, they do not achieve variable stiffness characteristics, consequently being difficult to be applied to manipulators used in MIS. In this study, we proposed a manipulator that can be magnetically steered by a permanent magnet at the end and can have variable stiffness characteristics by a phase transition of graphene polylactic acid (GPLA). Thus, the proposed manipulator is easy to fabricate and miniaturize as a magnetic steering MIS manipulator. To verify the magnetic steering and variable stiffness performances of the proposed manipulator, various basic experiments and analysis simulations were executed. In addition, by applying the discriminating properties of the proposed manipulator (magnetic steering, variable stiffness), we can construct a double-segment manipulator with variable stiffness and verify its implementation in postures which are difficult to achieve in other MIS manipulators.