Abstract
Most of the instruments for laparoscopic surgery are slender because they need to be inserted into the abdominal cavity through the small hole of a trocar. Large traditional instruments for abdominal surgery cannot be utilized for laparoscopic surgery. To overcome this problem, we have proposed assemblable instruments for laparoscopic surgery that can be disassembled to pass through a trocar and assembled into large instruments inside the abdominal cavity. As an example, we developed an assemblable pursestring suture instrument (PSI) for laparoscopic surgery. The PSI is a T-shaped instrument used to suture the cut end of a tubular organ; it is required to anastomose the cut end to another cut end. A PSI needs to have adequate rigidity and a grip force. To meet these requirements, this paper proposes a two degree of freedom folding mechanism. Experiments with the assemblable PSI show that it can be assembled in 46 s, and disassembled in 32 s on an average and generate a large grip force of 75 N. Moreover, in vivo experiments confirm that the assemblable PSI can effectively make a purse string suture.
