Precise Control and Experimental Evaluation of a Novel Endoscopic Suturing Device for Large Perforations

A novel endoscopic multi-firing clip applicator (EMFCA) system was developed for closing large perforations, in which the clips was deployed by pushing through a tendon-sheath actuation system (TSAS). However, the closure performance is heavily dependent on the pushing force transmitted to the clips which shows different nonlinear characteristics comparing with pulling transmission. Therefore, this study aimed to develop a pushing transmission model of the TSAS for precise control of the EMFCA, and verify its applicability. A pushing transmission model of the TSAS was proposed and simulated. Meanwhile, a TSAS-based push-transmission platform was designed to identify the parameters which potentially affect the transmission efficiency. Besides, ex vivo endoscopic stomach perforation closure experiments were carried out with the EMFCA system to validate the reliability of the proposed model. The experiment indicated that the results of simulation had a satisfactory agreement with the experimental data. The force and displacement transmission presented a linear relationship during the loading and unloading period, and the transmission efficiency and dead zone were affected by the tendon-sheath diameter ratio and the curvature. The ex-vivo testing revealed that a superior closure was obtained by using the EMFCA through effective deformation of the clip to anchor loop tightly onto the tissue when the input forces were in the range of 21–30 N. The proposed pushing transmission model could provide a reliable prediction of force feedback which contributes to accuracy control of the flexible endoscopic instrument with TSAS and improving the safety of endoscopic surgery.