How to Design and Create a Cardan Shaft for a Single Port Robot by Selective Laser Sintering

With the spread of endoscopic interventions the postoperative stress for patients has been reduced clearly. These interventions through natural orifices of the body (Natural orifice transluminal endoscopic surgery: NOTES) need miniaturized instruments with high precision, high range of motion and a high force load transmission. Our aim is to develop a mechatronic, single-port robotic system to guide and move flexible endoscopic instruments and optics inside the body. The system should be adapted to a flexible endoscope and consists of two flexible and actuated end-effectors that carry and manipulate flexible instruments. Due to the flexible end of the structure, laparoscopic single-port surgery through one incision and endoscopic surgery through a natural orifice would be possible. The concepts and prototypes were realized by selective laser sintering (SLS). One way to create flexible structures for a single use robot is to use universal joints assembled together in series. Next, selective laser sintering can now print these parts with the joints already assembled, in one part. There is no need for assembling or adhesive bonding. The final step is to replace the real joints of the cardan shafts with elastic joints. The proposed joints are made by the powder PA 2200 based on nylon. This basic powder is certificated as biocompatible according to ISO 10993-1. The challenge in this new field of printed medical robotics is to define a manufacturing process that enables you to design a part, create it by SLS and get it approved as a medical product.