Robotic Sewing and Knot Tying for Personalised Stent Graft Manufacturing

Our research team at the Hamlyn Centre presented a versatile robotic system for sewing 3D structured object

Vascular disease is a major contributor to cardiovascular deaths in the world. The incidence of abdominal aortic aneurysms increases signi?cantly with age-by over 300% for those at age 70 compared to those at age 50. Endovascular therapy avoids major trauma associated with an open operation, with clear advantages in terms of reduced morbidity and mortality, especially in patients unable to withstand traditional open surgery.

This procedure of endovascular intervention requires the use of personalised, custom-made stent grafts with bespoke openings (fenestrations) and branches, which could provide a better ?t for a patient’s anatomy. These personalised stent grafts are currently handmade by means of sewing thousands of stitches, which are expensive and time-consuming. The long delay in customised graft manufacturing can subject patients to the risk of aneurysm rupture and precludes treatment to patients with acute symptoms. The development of an automated stent graft sewing technique would be very helpful to increase the speed of personalised stent manufacturing.

Robotic Sewing and Knot Tying for Personalised Stent Graft Manufacturing This project presents a versatile robotic system for sewing 3D structured object, i.e. personalised stent grafts. With the use of a customised sewing device and closed-loop visual servoing control, an all-in-one solution for sewing personalised stent graft is demonstrated. Stitch size planning and automatic knot tying are proposed as the two key functions of the system. Using the stitch size planning method, sub-millimetre sewing accuracy is achieved for stitch sizes ranging from 2mm to 5mm.

In addition, a thread manipulator, with the capability of thread management and tension control is also proposed to perform successive knot tying to secure each stitch. Experiments are designed to test these two proposed methods. Their performance and further improvement are discussed. Besides industrial sewing, the system also shows the potential to be transferred to other clinical areas such as surgical suturing.