ABSTRACT
Minimally invasive surgery (MIS) has recently seen a surge in clinical applications due to its potential benefits over open surgery. In MIS, a long manipulator is placed through a tortuous human orifice to create a channel for surgical tools and provide support when they are operated. Currently the relative large profile and low stiffness of the manipulators limit the effectiveness and accuracy of MIS. Here we propose a new foldable manipulator with tunable stiffness. The manipulator takes a braided skeleton to enable radial folding, whereas membrane is used to seal the skeleton so as to adjust stiffness through creating negative pressure. We demonstrated experimentally, numerically, and analytically that, a flexible and a rigid state were obtained, and the ratio of bending stiffness in the rigid state to that in the flexible state reached 6.85. In addition, the manipulator achieved a radial folding ratio of 1.95. The proposed manipulator shows great potential in the design of surgical robots for MIS. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B, 2019.