Learning curve of surgical novices using the single-port platform SymphonX: minimizing OR trauma to only one 15-mm incision

Background Minimally invasive single-port surgery is always associated with large incisions up to 2–3 cm, complicated handling due to the lack of triangulation, and instrument crossing. The aim of this prospective study was to report how medical students without any laparoscopic experience perform several laparoscopic tasks (rope pass, paper cut, peg transfer, recapping, and needle threading) with the new SymphonX single-port platform and to examine the learning curves in comparison to the laparoscopic multi-port technique. Methods A set of 5 laparoscopic skill tests (Rope Pass, Paper cut, Peg Transfer, Recapping, Needle Thread) were performed with 3 repetitions. Medical students performed all tests with both standard laparoscopic instruments and the new platform. Time and errors were recorded. Results A total of 114 medical students (61 females) with a median age of 23 years completed the study. All subjects were able to perform the skill tests with both standard laparoscopic multi-port and the single-port laparoscopic system and were able to significantly improve their performance over the three trials for all five tasks—rope pass (p < 0.001), paper cut (p < 0.001), peg transfer (p < 0.001), needle threading (p < 0.001), and recapping (p < 0.001). In 3 out of 5 tasks, medical students performed the tasks faster using the standard multi-port system—rope pass (p < 0.001), paper cut (p < 0.001), and peg transfer (p < 0.001). In the task recapping, medical students performed the task faster using the new single-port system (p = 0.003). In the task needle threading, there was no significant difference between the standard multi-port system and the new single-port system (p > 0.05). Conclusion This is the first study analyzing learning curves of the commercially available SymphonX platform for abdominal laparoscopic surgery when used by novices. The learning curve and the error rate are promising.

Performance evaluation of conductive tracks in fabricating e-textiles by lock-stitch embroidery

Lock-stitch embroidery has been the centre of much interest as a versatile and precise method of producing conductive tracks in the fabrication of wearable electronic devices. However, improper fabrication parameter settings could result in the nonconformity of the conductive tracks and damage the conductive coating of the conductive yarns. In this study, we evaluate the appearance quality, dimensional stability and electrical resistance of conductive tracks by taking into account the embroidering speed (ES), stitch length (SL), needle thread pre-tension (NTP) and embroidering direction (ED). The conductive tracks are embroidered onto knitted fabric in different directions with silver-coated polyamide yarn as the needle thread. The results show that stitching the conductive tracks in the wale direction results in a more uniform stitch lines in comparison to the other directions. To resolve the problem of floated stitches, it is recommended that an SL of 4 mm and a higher NTP are used. The percentage of shrinkage in the wale direction is lower than in the course direction. The electrical resistance of the conductive tracks increases with a higher ES and shorter SL. It is also found that a thicker yarn is more sensitive to the NTP and some of the silver coating is rubbed off with an NTP of 50 gf. We also carry out an overlay plot analysis, through which we predict and validate the optimal embroidery parameters that balance appearance quality and electrical resistance. The technique parameters in this study can be used to embroider conductive tracks for smart clothing.

Influence of geometric parameters of the rotary hook on interaction of its elements in high-speed modes sewing machine

Purpose The purpose of this paper is to develop the analytical model of the rotary hook geometric parameters’ interconnections, which allows determining the characteristic modes of interaction of its elements. In this study, the interaction mechanism of the bobbin case, the rotary hook and the support finger was defined, which allows to reduce the unit vibro-impact activity. Design/methodology/approach As practice shows, the bobbin case sometimes turns against the rotary hook movement. This phenomenon can be used for the free passage of the needle thread. The change in the geometric parameters of the rotary assemble will allow to decrease its vibro-impact activity. Findings The interrelations of rotary assemble geometric parameters are established, and it is possible to determine the characteristic modes of its elements interaction and to establish a mechanism for controlling them. This allows reducing the vibro-impact activity of joint, improving friction modes and sewing technology. Criteria and values of a gap formation between the right contacting face of bobbin case and support finger protuberance are found. Research limitations/implications In the future, it is necessary to conduct research on the behavior of the rotary assemble elements in the frequency operating modes of the sewing machine. It is necessary to show the influence of the resonance modes of operation of the rotary hook drive on the interaction of elements. Practical implications The practical use of the results of the work makes it possible to reduce the vibratory impact of the shuttle, and also to create conditions for the smooth operation of the rotary hook and the bobbin case, and ensure the formation of a gap between the contacting face of bobbin case and support finger protuberance for the free passage of the needle thread. The results of the work can be used in the design of a rotary assemble with specified characteristic parameters and modes of elements interaction. Originality/value An analytical model of interrelations of geometric parameters of a rotating hook is developed. The characteristic modes of interaction of the rotary assemble elements were studied. The reasons for the vibro-impact activity of the rotary hook are studied. Also, the conditions under which the bobbin case will move against the direction of rotary hook rotation are determined.