# Design and Development of a Flexible 3D-Printed Endoscopic Grasping Instrument
## 4 Discussion
For both cases, the limiting factor to achieving greater forces was that the bending was performed manually. A work by [PERSON] et al. demonstrates an instrument that achieves a maximal bending force of 5.6 N, which is still notably lower than in our case [27]. Additionally, instead of bending force, several previous works focused exclusively on rigid laparoscopic instruments and reported on a similar metric called payload capability. In their cases, this metric ranged from 0.26 to 10 N [15, 47, 48, 49]. One noticeable difference is that payload capacity considers a range of tolerable deflection of the instrument under different loads that are applied to its tip. In our study, we did not systematically focus on such a metric. For flexible endoscopy, some deflection of the instrument could be regarded as an advantage since an instrument that does not deflect under outside forces could potentially perforate the delicate tissue of the GI tract during the process of insertion. In the assessment performed in the porcine model, the medical experts involved graded the instrument's properties as overall adequate for the intended use. The instrument's smooth shape minimized friction with the organ surface, and no limitations were observed during the insertions, due to the instrument's high degree of flexibility. However, it was noted that in some instances, more rigidity would be preferred, but without sacrificing flexibility. As rigidity and flexibility are two opposing properties, finding a balance is a challenging task that we tried to address. The need for improvement was observed mainly regarding the flexible shaft, as it encountered some degree of torsional deflection during the tests. This affected the responses of the distal tip to hand inputs when the instrument was highly bent. The instrument's maneuverability within the esophagus alongside the endoscope and bending through the leak opening was unconstrained due to its slender shape, high bending angle, and small bending radius. The latter performance of the instrument is supported by the measurements of the time necessary to perform different interventional tasks. As interventional endoscopic procedures are complex operations involving a wide range of tasks during their execution, we separately measured the time necessary to perform tasks that are commonly occurring. We demonstrated that the median time to insert a sponge in the region of the leak opening was 120 s, while a median of 70 s is necessary to properly enter and position the same sponge in the cavity. Additionally, the median time needed to remove an object from the cavity was measured to be 220 s, which is comparable to the time required for the removal of foreign objects from the esophageal region and stomach. As a limitation of the presented instrument, it must be noted that during repetitive and extensive use of the instrument, some elements of the bending section experienced failure, which raises the question of the instrument's durability in extended, repetitive use. A larger study is necessary to systematically record and analyze such occurrences. Regardless, due to its inherent affordability and a recently increasing adoption of single-use devices in endoscopy, this limitation might be readily surpassed [50, 51, 52]. Furthermore, it must be noted that an objective comparison with other works regarding the grading of the instrument and the time necessary to perform various interventional tasks is lacking, due to the specificity of the presented instrument and experiments in the porcine model.