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.

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 a prenatal temporary tracheal occlusion, which enlarges the fetal lungs, and is a promising procedure 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, the 3-unit robotic manipulator with ball joint-shaped arthroses and a shaft diameter of 2.4 mm using a wire-driven mechanism has been developed to approach the fetal trachea without the risk of damage to fetal tissue. The robotic manipulator has a thin structure and 7 degrees of freedom to avoid damage to the fragile fetal cells. However, the positioning control of the robotic manipulator is very difficult. In this paper, the mechanism of the robotic manipulator positioning control was confirmed by measuring the motion of each unit through the experiment. Additionally, a simulation was developed to estimate the mechanism of the robotic manipulator positioning control, and an approach method was considered. The results of the evaluation experiment suggested that the robotic manipulator could approach the fetal trachea through the mouth, and that the contact force was controlled to under 0.05 [N].

A bending laser manipulator of 2.4 mm in diameter has been developed for intrauterine fetal surgery. This manipulator deflects a laser fiber in any direction thorough 90 degrees. The results of a positioning test and in vitro/in vivo tests are reported. Meanwhile, creep tests for fetal rat tissue of 16 to 20 days in gestation were performed to evaluate fetal tissue fragility. Unique features of fetal rat tissue compared to other soft organs are discussed and a viscoelastic model of the fetal rat tissue was proposed. The result of the modeling will be used not only for fabricating fetal tissue phantom but also for the force control of robotic application for fetal surgery.

This paper describes a manipulator for controlling position and posture of fetus in uterus and a surgical procedure for supporting the fetus in intrauterine surgery. The manipulator is equipped with multiple linkages and a balloon to support the fetus softly in the uterus. The linkages with two bending mechanisms are designed for inserting the balloon to an optimal position under the fetus. The balloon is fold before the operation and inflated by saline water after arriving at the required position in the uterus. Accuracy evaluation showed that the standard deviations of the bending angle of the wire-driven mechanism and the linkages-driven mechanism were 1.0 degree and 2.5 degree, respectively. Force experiment showed that the balloon-type stabilizer could generate load-bearing power of 500 gf. Furthermore, the manipulator could be well controlled with guidance of ultrasound images. The manipulator could minimize injure to the fetus since the area contacted with the fetus by the balloon could be well controlled.

We propose a new surgical robotic system for intrauterine fetal surgery in an Open MRI. The target disease of the fetal surgery is spina bifida or myelomeningocele that is incomplete closure in the spinal column and one of the common fetal diseases. In the proposed surgical process, the abdominal wall and uterine wall would not widely be opened but rather surgical instruments inserted through the small holes in both walls to perform minimally invasive surgery. In this paper, a prototype of the micro manipulator of diameter is 2.4mm and bending radius 2.45 mm is presented. The diameter and bending radius of this manipulator is one of the smallest ever developed among surgical robots to the best of the knowledge of the investigating authors. The mechanism of the manipulator includes two ball joints and is driven using four wires able to bend through 90 degrees in any direction. The features of the mechanism include a small diameter, small bending radius, ease of fabrication, high rigidity and applicability for other surgical applications. Although the manipulator is not yet MRI compatible, the feature of the prototype demonstrated the feasibility of robotic intrauterine fetal surgery.