No abstract

The implementation of origami techniques into disposable surgical robotic tools is a promising research area with numerous clinical applications. Origami allows for flat foldable structures that can fit through small incisions, reducing patient scarring and recovery time as well as surgical costs. Devices that can provide tight navigation through curved anatomical pathways are crucial during these types of surgery, and can cost anywhere from hundreds to several thousands of dollars. It was hypothesized that an origami design based on a chain of deployable compliant rolling-contact elements (D-COREs) could be applied to design and fabricate a medical endoscope from a single sheet of 2D material ( Fig. 1) to simplify fabrication and reduce the cost to under $100 [1][2][3]. We used software to model the physical actuation range of the endoscope and tested actuation of the D-COREs with shape-memory alloy (SMA). MethodsThe first prototype for the endoscopic structure was fabricated by laser cutting an origami pattern. The flexible endoscopic origami structure consists of a central lumen and a chain of the Deployable Compliant Rolling-contact Element (D-CORE) designs. Two rolling surfaces are connected by flexible bands which can be folded into a flat state or relaxed and deployed into a functional joint. Each joint can be actuated through the use of a pair of SMA springs which return to their memory shape when heated to 98°F. An electric current was used to heat each spring one at a time in order to contract them into a compressed coil and effectively actuate the joint. Figure 2 shows a 3D printed prototype containing two D-CORE joints mounted in parallel which are actuated to an angle of 20 degrees. Each D-CORE can be mounted perpendicularly to the next adjacent D-Core to provide 3D motion and multiple degrees of freedom to the endoscope. The geometry of the D-CORE structure was analyzed in order to model the physical actuation range. The geometric illustration in Figure 3 was used to develop equations to determine the X and Y coordinates of the distal end of the endoscope. ResultsThe 3D printed D-CORE was successfully actuated by passing an electric current through nitinol SMA springs.