Design of a Bistable Origami Stent with Pneumatic Actuation

Abstract: What if stents could be easier removed when complications arise or removed once theirjob has been done? No matter how perfect a stent design becomes, the fundamental issueis that a foreign object in the body under extended periods eventually will cause devicedegradation and complications. So instead of making a long-term solution of a perfectstent, the focus in this paper is redirected from expensive materials to a simple design,with simple materials. The goal of this master’s thesis was, therefore, to design a stentthat incorporates bistability with the use of origami so it has the possibility of beingremoved after actuation. The result is a family of designs where the bistable behavior,cylinder roughness, and cylinder length are some of the parameters that can be adjusted.The design family is made out of a cylinder body based on Waterbomb origami and twobistable star elements at the cylinder’s endpoints. This design’s bistability is observedmathematically, with a projection approach, and then in simulation by doing an FEAAbaqus. Prototypes are manufactured with laser-cut designs and an assembly consistingof laying two stif l ayers w ith a n a dhesive l ayer i n b etween. T hese p rototypes a re thenused in an experimental setup that results in a clear display of the bistability, scalability,and adaptability of the design. The paper also gives a step-by-step guide in reproducingthe designed stent and suggestions for further research where applying the design toa medical setting is the most prominent one. With the design’s very fexible nature,further study also includes other actuation uses that could beneft from this radially andlongitudinal expanding bistable actuator.