A Bio-Inspired Tendon-Driven Continuum Robot for Treatment of Twin-to-Twin Transfusion Syndrome

Twin-to-Twin Transfusion Syndrome (TTTS) is a life-threatening condition that occurs in monochorionic twin pregnancies, where one twin receives more blood flow from the shared placenta, while the other twin receives less. This imbalance can lead to cardiac failure, and in severe cases, even death of one or both twins. TTTS is treatable by a modified fetoscopic laser photocoagulation (FLP) of placental anastomoses. However, this procedure is challenging with conventional rigid instruments, especially for accessing the anterior placenta. These instruments have limited degrees of freedom hindering their ability to navigate the expansive uterine cavity and increasing movement around the amniotic membrane which could lead to Premature Rupture of Membranes (PROM) before labor begins. In this paper, we present a novel continuum manipulator inspired by human condyloid joints. The design has the following advantages: (1) a flexion range of up to 230°, (2) capability for omnidirectional bending, (3) torsion prevention with its ellipsoidal ring shape, and (4) a higher bending resolution and compliance compared to other rolling joint manipulators. The manipulator designed is a scaled-up prototype intended for miniaturization to fit a 10 French (3.3 mm outer diameter) trocar. We successfully demonstrate the performance and feasibility of the manipulator for TTTS surgery by testing its bending range and workspace volume.