Development of 6-DOF wire-driven robotic manipulator for minimally invasive fetal surgery

The clinical target of this study is intratracheal balloon occlusion from minimally invasive fetal surgery for Congenital Diaphragmatic Hernia (CDH). The target for the surgery is prenatal temporary tracheal occlusion which enlarges the fetal lungs, and this procedure is promising for severe cases. A balloon is supposed to be inserted for tracheal occlusion using the manipulator. We propose a novel robotic manipulator for intrauterine fetal surgery for tracheal occlusion. In this study, a prototype of the robotic manipulator using a wire-driven mechanism has been developed. The manipulator is thin in structure and has multiple degrees of freedom to avoid damage to the fragile cells of the fetus. Specifically, we describe our development of the 3-unit robotic manipulator with ball joint-shaped arthroses and shaft diameter of 2.4 mm. The mechanism of the robotic manipulator was designed for providing the bending motion and controlling the contact force at its tip by the tension of the driven wires. Results of the experiment suggested that the contact force was controlled to under 0.04 N to insert the manipulator through the mouth of the fetus into the trachea without causing damage to the fetal tissues or changing the fetal attitude in the uterus.