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The human stomach, consists of four different layers: the mucosa, the submucosa, the muscularis externa and the serosa. Three different layers form the mucosa: the surface epithelium (containing gastric pits and gastric glands), the lamina propria, and the muscularis mucosae. The muscularis ext. consists of a longitudinal external muscle layer, a circular middle muscle layer and an oblique internal muscle layer [1, 2].

Different pathologies (gastric ulcer, inflammation, malignancies, trauma) can lead to gastric perforation. This indication can lead to a life-threatening disease and therefore requires a quick and efficient treatment.

The treatment of a stomach perforation is done either by an open or laparoscopic surgery whereat the muscularis externa is closed by sewing and the mucosa remains untouched (Fig.1) [3].

Differentiation of non-sewing and sewing layer of a porcine stomach wall. As shown, the muscularis ext., covered with serosa (=layer that is sewed; black arrow) can be distinguished from the mucosa (layer not sewed; orange arrow)

Primary closure by interrupted sutures, closure by interrupted sutures covered with a pedicled omentum on top of the repair (Cellan-Jones repair) and plugging the perforation with a free omental plug (Graham patch) are the most common techniques [4].

Those surgical techniques require much training and patient`s safety during surgeries is highly dependent on the surgeons skills [5, 6] showed that even a one-day surgical-skill training course for medical students improved their surgical skills. Moreover, simulation-based training is beneficial in, for instance training laparoscopic surgery [7].

However, surgical training in humans has a number of restrictions such as patient safety issues, ethical and economic considerations or lack of exposure to specific surgical procedures [8,9,10,11,12].

Instead, animal tissue is often used in research and education, especially if there are no sufficient non-cadaveric training models on the market. So far, surgeons are still using porcine stomachs for training gastric perforation surgery. The digestive system and, the structure of the stomach wall of pigs is similar to all other monogastric mammals. Therefore, the stomach of a pig has a similar structure and function as a human stomach. Additionally, porcine stomachs are usually easily available and of low-costs [13].

The use of animal tissue has also many disadvantages and limitations, for example the short time frame where the tissue is usable and the need for the required infrastructure (cooling capabilities, wet areas), [14,15,16,17,18,19]. Furthermore, ethical aspects are still a compelling reason for using artificial training models instead of biological organs or tissue [20, 21].

Therefore, artificial models similar to biological tissue are desirable substitutes for real biological tissues and organs for applications in research, medical training, and teaching. However, accurately mimicking the mechanical and haptic properties of a tissue or an organ is a challenge. In order to mimic soft tissue, potential materials include soft compliant substances such as silicones, gelatine, or hydrogels [22].

Many different silicones are available on the market, providing a variety of flexibility and strength. To combine the advantages of a long lifetime, realistic mechanical properties, similar haptic conditions and a good working environment, a silicone training model could be a good surrogate [23]. It was already shown in [24] and [25] that silicone models cast in 3d printed moulds improve the skill level of surgeons when used in surgical training.

Within this study, a set of artificial silicone models of a stomach wall with realistic mechanical and haptic properties is developed to be used in training of gastric surgery. To support the open-source notion, the models should be easy to manufacture and cheap to copy.

The silicone models are compared with fresh porcine stomach wall in terms of needle penetration force characteristics in a mechanical test setup. Additionally, a systematic haptic comparison, including appearance and piercing- and tear out forces was performed. Similar investigations for testing artificial tissue have already been able to achieve some results, such as in [26,27,28].

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A mechanically validated open-source silicone model for the training ... - BMC Medical Education