Design, Fabrication, and Testing aSemiautomatic Sewing Device forPersonalized Stent Graft Manufacturing
For the treatment of abdominal aorticaneurysm, a personalized stent graft is used to ensure thatit fits tightly to the patients vessel geometry. A personalizedstent graft is usually handmade, which requires thousandsof stitches and can take weeks or even months to complete.This delay may expose the patient to the risk of aneurysmrupture. This paper presents a robotic sewing device thatcan enhance the stent graft sewing speed by providing au-tomated needle manipulation. It simplifies the sewing pro-cess and has the potential to achieve fully automated stentgraft manufacturing via a vision-guided system. https://vssewingmachine.in/ The devicefeatures a sewing probe that can switch a double-pointedsemicircular needle between two movable jaws. This for-goes the need for manual needle handling including grasp-ing, driving rotation, releasing, and regrasping, which re-quires a high level of manual dexterity and attention. Thispaper presents the design of the device, its mechanical syn-thesis and experimental validation. The focus of the paperis on the linkage parameter optimization and needle lockingmechanism design. The proposed device has been fabri-cated using 3-D rapid prototyping techniques, and its per-formance has been compared with the conventional manualsewing method. The experimental results show that the de-vice can achieve a 30% reduction of the completion timefor a stitching task while achieving better consistency andquality of the stitches.
Vascular disease is a major contributor to cardiovascu-lar deaths in the Western world. Endovascular therapy hastransformed the management of vascular disease, with clear ad-vantages in terms of reduced morbidity and mortality, especiallyin patients unable to withstand traditional open surgery due to comorbidities. For the treatment of abdominal aortic aneurysm,personalized stent grafts are required to fit the exact geometry ofthe patient. For complex aneurysms, fenestrated and branchedendografts are further required to ensure continued perfusion ofrenal and visceral vessels. Manufacturing of these personalizedstent grafts remains a lengthy, expensive process as they arestill fabricated mostly by hand. Solutions have been proposedto manufacture off-the-shelf standardized stent graft with auto-mated processes . VS Sewing Machines However, the use of standard stent graftsmay lead to an inadequate seal of the aneurysm sac. Stent mi-gration may also happen in the long term. To overcome thisproblem, personalized, custom-made stent grafts with an exactfit to a patient’s anatomy are emerging as an appealing solution.These personalized stent grafts with complex shapes featurethousands of stitches; assuring the sewing quality can be ex-tremely costly and time consuming with existing techniques.Currently, manufacturing one such stent graft can take up to6–12 weeks. The long delay in stent graft manufacturing mightexpose the patient to the risk of aneurysm rupture. The develop-ment of an automated sewing technique for custom stents wouldimprove the state-of-the-art manufacturing and help the patientsmore effectively with ad hoc solutions. Recently, innovation in3-D sewing is an important topic for industrial manufacturing.Extensive research has been carried out for developing single-sided sewing heads that can work on 3-D objects with closedsurfaces. For example, a two-needle-head RS 530  (KSLKeilmann, Lorsch, Germany) has been developed for sewingfabric reinforced structures of aircraft parts. Automated sewinghas also been widely researched in the textile industry. Most ofthe existing research has been focusing on incorporating sensorsand robots into conventional sewing machines to automate a fewspecific processes. Relevant topics include fabric tension con-trol for robot-assisted fabric feeding , sewing seam trackingusing an optical sensor  or using a camera system , andmultiarm robotic sewing .The use of threads to bind objects is not only employed in thefield of textile industry. It has a wide range of applications inmedicine. Due to the increased use of robotic-assisted systems inthe field of minimally invasive surgery, various suturing devicesthat aim to automate the suturing procedure have been devel-oped, including the Autosuture EndoStitch (Covidien, Dublin,Republic of Ireland) , the SILS Suturing Device (Covidien, Dublin, Republic of Ireland) , Endo360oSuturing Device,(EndoEvolution, Raynham, MA, USA) , the PROXISURESuturing Device (Ethicon, NJ, USA) , the Switch SuturingDevice(Mellon Medical, The Netherlands)  and the EagleClaw endoscopic suturing device (Olympus Medical SystemsCorp., Japan) . According to the ways to operate the nee-dle, these devices can be classified into two categories. For thefirst category, Switch, EndoStitch, and SILS systems switch adouble-pointed needle between two opposing jaws. A lockingmechanism is built in each jaw to lock the needle. For the sec-ond category, devices, such as Endo360oand PROXISURE,work by continuously rotating a circular needle to performstitching. Based on the aforementioned suturing devices, vision-guided robotic suturing systems, such as KidsArm AnastomosisRobot  and Smart Tissue Autonomous Robot (STAR) ,, have demonstrated that it is feasible for a robot to performanastomosis autonomously.When comparing the aforementioned industrial sewing meth-ods with surgical suturing, the industrial one usually relies onusing a fixed sewing machine that rapidly produces only onespecific type of stitch, while the surgical suturing is more versa-tile, which can perform various types of stitches as well as knottying, albeit with slower speed. Furthermore, industrial sewingmachines can be quite large and complex. They require synchro-nization of the needle and bobbin in a sophisticated, perfectlymatched timing sequence. Traditional sewing machines workonly for flat sewing objects. The single-sided sewing head canperform sewing on the outer surface of generic 3-D objects;however, these objects are relatively big and heavy. The surgi-cal suturing devices have an advantage that they are relativelysimple and compact, suitable for working in a confined space,such as a corner or a tight lumen. Finally, the stitch pattern of theindustrial sewing machines is quite thick because two threadsare usually interwoven to perform continuous sewing, whilethe surgical suturing only uses a single thread. For stent graftmanufacturing, multiple stitch types are required, which includerunning stitches along the stent and tying knots to fix the apexesof the sinusoidal-shaped stent. To access corners between thebranches, the sewing device needs to have a small and compactfootprint.Based on the above-mentioned considerations, the idea fordeveloping the new sewing device for sewing stent graft wasinspired mostly by the surgical suturing devices. In previouswork –, a vision-guided multirobot manufacturing sys-tem for the flexible production of personalized medical stentgrafts was proposed. It features two robotic arms, each holdinga surgical needle driver to perform the task. One drawback ofthis system is that it requires a frequent releasing and regraspingof the suturing needle, which introduces a significant challengefor automating the task. In this paper, a patented sewing de-vice (seeFig. 1) developed by the authors is used for sewingpersonalized stent grafts.The proposed device can not only be used as a hand-helddevice to increase manual stent graft sewing speed, but alsobe integrated into a vision-guided robotic sewing system toachieve fully automated stent graft manufacturing . Com-pared with the existing sewing/suturing systems, the proposeddevice has three distinctive features. First, it is the first device which can switch a double-pointed semicircular needle to per-form stitching. The needle moves by following its tangentialdirection, which is vital to guarantee a minimal tearing forceapplied to the object being sewed. Compared with the deviceusing a straight needle, the proposed device is more suitable forsewing stent grafts because a curved needle can easily movearound the stent without deforming the stent. Second, the nee-dle has a large exposure area out of the device. Compared withthe suturing devices whose needle is hiding inside the circularhousing, the operator of the proposed device can use the needletip as a reference for targeting a stitching point. Furthermore, theexposed needle tip can also be used to interact with the threadto perform knot tying. Third, the needle is locked by only withfriction such that no notches are required on the needle body,making the needle pierce through the object more smoothly.The following are the main contributions of this work.1) The proposition of a novel sewing device that is multi-functional, being possible to implement it in the textileand surgical industries. The device is versatile and can beused either for faster manual sewing or automated roboticsewing.2) The mechanical synthesis and experimental validation ofthe device, ranging from the investigation of different linkparameters for improving the performance of the needledriving mechanism to utilization of FEA to assist thedesign of the NiTi needle locking mechanism.3) The manufacturing of the proposed concept with vari-ous rapid-prototyping techniques, such as selective lasermelting, laser cutting, and electrical discharge machining.4) Experimental validation with a detailed user study to ver-ify usefulness of the proposed device.