Assemblable pursestring suture instrument for laparoscopic surgery

We have proposed a novel concept of assemblable instruments for laparoscopic surgery, that is, their parts can be disassembled to pass through trocars and can be reassembled inside the abdominal cavity to become large instruments. By applying this concept, this paper proposes an assemblable pursestring suture instrument (PSI). In gastrectomy, a purse string suture on the esophagus is made preparatory to the anastomosis of the esophagus and the small intestine with a circular stapler. A traditional PSI cannot pass through a trocar because of its T-shaped jaws and a PSI that can be used in laparoscopic surgery is highly desired, which motivates us to develop the assemblable PSI. We have developed two prototypes of the assemblable PSI. The experiment with the first prototype verifies that it can be assembled in the abdominal cavity. However it cannot generate a grip force enough to hold the esophagus. We propose a two-DOF unfolding linkage mechanism for the gripper of the second prototype. The in vivo experiment with the second prototype verifies that it can make a satisfactory purse string suture.