Design of a Compliant Endoscopic Suturing Instrument

This paper outlines the development and initial optimization of a compliant endoscopic suturing instrument. The developing field of Natural Orifice Transluminal Endoscopic Surgery requires innovative instruments to meet the size limitations inherent in this type of minimally invasive surgery; using compliant mechanisms is proposed as one method of meeting this requirement. Three initial compliant designs were created, modeled, and compared for a distal opening of 10 mm. Restricting these designs so that they must fit within a 3.3 mm working channel is currently unique in endoscopic suturing instruments. A design that utilizes contact for stress relief and intertwining parts for added deflection was selected from the three. ANSYS® was used to aid in graphical optimization to maximize the jaw opening and maximize the puncture force of the selected design. The best geometry has a distal opening of 13.8 mm at the tips and can supply a puncturing force of 6.33 N. A prototype has been machined using the optimized dimensions and is ready to be tested. This initial study in compliant suturing instrument designs has revealed response patterns for the chosen geometries that will lead to further refinements and improvements in future models.Copyright © 2007 by ASME